By

Jon Gutteling

Low thoracic versus lumbar epidural anesthesia during the first phase of labor

J. Gutteling, RUG ID: 1924214

Mentor: J.M.G. Cobben, Anesthesiologist

15 October 2012 – 15 march 2013

Anesthesiology Department, Deventer Hospital

Abstract (Dutch) 1

Samenvatting

Introductie

Er zijn aanwijzingen dat de pijn die vrouwen ervaren tijdens de baring intenser is dan

vrijwel alle pijn van andere oorsprong. Epidurale analgesie (“een epiduraal”) is

wereldwijd een veel toegepaste anesthesietechniek die zeer geschikt is voor perinatale

anesthesie. De meest gebruikte hoogte om een epiduraal te prikken is de (laag)

lumbale regio. Gezien het feit dat de meeste pijn tijdens de ontsluitingsfase wordt

gevoeld via zenuwwortels ter hoogte van T10-L1, is onze hypothese dat thoracale

epidurale anesthesie resulteert in betere analgesie en minder kunstverlossingen en

sectio’s dan lumbale epidurale anesthesie tijdens de ontsluitingsfase van de partus.

Methoden

Om deze hypothese te toetsen werden twee studies opgezet. Ten eerste een

retrospectieve dossierstudie naar alle bevallingen met epidurale analgesie de

afgelopen vier jaar, om te kijken naar de primaire uitkomst van de bevalling.

Daarnaast een prospectieve observationele studie, waarin alle vrouwen met een

thoracale (T10-L1) of lumbale (L1-L5) epidurale katheter werden geïncludeerd. De

pijn die ze beleefden werd elk uur met de visueel analoge schaal (VAS) vastgelegd,

daarnaast werd bijgehouden hoe snel en hoe vaak er door de barende om extra

pijnstilling werd gevraagd.

Resultaten

De retrospectieve database bevatte bruikbare gegevens van 1172 patiënten. Hiervan

had 96 een thoracale en 1096 een lumbale epiduraal. We vonden geen statistisch

significante resultaten betreffende de incidentie van spontane bevallingen, sectio’s en

kunstverlossingen. Ook de APGAR score van de pasgeborene en de tijd vanaf het

plaatsen van de epidurale katheter tot de bevalling klaar was lieten geen verschil zien.

In de prospectieve studie zijn 44 patiënten geïncludeerd. Hiervan kregen 13 een

thoracale epidurale katheter en 31 patiënten een lumbale. Grafische weergave liet

mogelijke verschillen in VAS scores zien, er waren echter geen significante

verschillen in VAS scores of vraag naar extra pijnstilling. Wel was er een trend van

kortere ontsluitingsduur na het plaatsen van de epiduraal te zien bij de thoracale

groep.

Conclusie

We vonden geen significant verschil in door de patiënten gerapporteerde pijnscores in

de twee groepen. Ondanks dat er aanwijzingen zijn dat er verschillen zijn tussen

epidurale katheters op thoracale en lumbale segmenten, zoals een kortere totale

ontsluitingstijd en minder vraag naar extra pijnstilling in de thoracale groep, zijn onze

resultaten niet conclusief. Er is meer onderzoek nodig naar het verschil in

pijnbestrijding en bevallingsuitkomst tussen epidurale analgesie op deze twee

hoogtes.

Abstract 2

Abstract

Introduction

There are indications that the pain parturients experience during labor is one of the

most intense pain experiences known. Epidural analgesia (“an epidural”) is a widely

used central neuraxial block very suitable for perinatal analgesia. The most common

used puncture site for epidural analgesia is in the lumbar region. Given the fact that

most pain experienced during the first phase of labor originates from the low thoracic

(T10- L1) spinal segments, we hypothesized that a epidural catheter placed in the

lower thoracic epidural space would result in better analgesia and less instrumental

assisted vaginal deliveries and caesarian sections than a catheter placed in the lumbar

epidural space.

Methods

To test this hypothesis, two studies were set up. Firstly a retrospective assessment of

all epidurals during labor performed in the Deventer Hospital the past four years, to

assess possible effects on primary labor outcome. Secondly a prospective

observational study in which we included all parturients who received lumbar (L1-L5)

or thoracic (T10-L1) epidural analgesia. We recorded pain using the visual analog

scale (VAS) and the frequency of escape bolus requests during the first phase of

labor.

Results

The retrospective study had usable data from 1172 patients. Ninety-six received an

epidural catheter in the thoracic region and 1096 a lumbar one. We found no

significant differences in incidence of caesarian sections, spontaneous deliveries and

instrumental deliveries. APGAR scores and total labor time were not significantly

different. In the prospective study we included 44 patients. Thirteen had a thoracic

and 31 a lumbar epidural catheter. While graphical representation did look promising,

there were no significant differences in VAS scores, amount of escape bolus requests

and time until escape bolus requests. A trend showing patients in the thoracic epidural

group requiring less time between the puncture and transition to the delivery phase

was seen.

Conclusion

We found no significant difference in VAS pain scores reported by parturients with

epidural catheters on lumbar or thoracic levels. Though there are indications that there

are differences in the degree of analgesia and other labor parameters between the two

epidural level modalities, such as a shorter total labor time and fewer escape bolus

requests in the thoracic group, our results remain inconclusive. More research is

needed to further objectify the difference in pain relief and labor outcome by thoracic

and lumbar epidurals.

Table of Contents 3

Table of Contents 1. Introduction ...................................................................................................................... 4

1.1 Physiology of labor pain .............................................................................................................. 4

1.1.1 Stages of labor ................................................................................................................................................... 4 1.1.2 Pain during labor ............................................................................................................................................. 4

1.2 Epidural anesthesia ..................................................................................................................... 5

1.2.1 Introduction to epidural anesthesia ........................................................................................................... 5 1.2.2 Brief history ........................................................................................................................................................ 5 1.2.3 Anatomy ............................................................................................................................................................... 5 1.2.4 Technique ............................................................................................................................................................ 6 1.2.5 Medication .......................................................................................................................................................... 7 1.2.6 Epidural analgesia during labor ................................................................................................................. 7 1.2.7 Complications .................................................................................................................................................... 7

1.3 Research question ........................................................................................................................ 8

2. Methods ............................................................................................................................ 9 2.1 Retrospective analysis.................................................................................................................. 9

2.1.1 Data collection .................................................................................................................................................. 9 2.1.2 Population and collected data ..................................................................................................................... 9 2.1.3. Statistical Analysis .......................................................................................................................................... 9

2.2 Prospective analysis ................................................................................................................... 10

2.2.1 Design ................................................................................................................................................................ 10 2.2.2 Measurements ................................................................................................................................................. 10 2.2.3 Study population ............................................................................................................................................ 10 2.2.4 Statistical analysis ......................................................................................................................................... 11

3. Results ............................................................................................................................. 12 3.1 Retrospective study results ....................................................................................................... 12

3.1.1 Labor outcome ................................................................................................................................................ 12 3.1.2 Height of the epidural and labor time .................................................................................................... 13 3.1.3 APGAR score after 5 minutes .................................................................................................................... 13

3.2 Results of prospective study ...................................................................................................... 14

3.2.1 Graphic representation ............................................................................................................................... 14 3.2.2.VAS score analysis ........................................................................................................................................ 14 3.2.3 ANOVA for repeated measures ................................................................................................................. 15 3.2.3.Inter-patient variables ................................................................................................................................. 16 3.2.4 Escape boluses................................................................................................................................................ 17

4. Discussion ....................................................................................................................... 18 4.1 Main results ................................................................................................................................ 18

4.2 Results in relation to other studies ........................................................................................... 19

4.3 Thoughts on the study ............................................................................................................... 20

4.3.1 Design of the prospective study ................................................................................................................ 20 4.3.2 Patient enrollment ......................................................................................................................................... 20 4.3.3 Measuring pain .............................................................................................................................................. 20 4.3.4 Parity ................................................................................................................................................................. 21 4.3.5 Sacral roots, sacral sparing ....................................................................................................................... 21 4.3.6 Epidural catheter location and epidural space fluid dynamics ..................................................... 21 4.3.7 Complications ................................................................................................................................................. 22

4.4 Clinical implications .................................................................................................................. 22

5. Conclusion ...................................................................................................................... 23

6. References ....................................................................................................................... 24

7. Acknowledgements ........................................................................................................ 26

Introduction 4

1. Introduction

1.1 Physiology of labor pain

1.1.1 Stages of labor

Labor is divided into three separate stages. (1) The first stage starts with regular

uterine contractions until full cervical dilation is reached. The first stage is further

divided in the “latent” and “active” phase following the increasing speed of cervical

dilation. The second stage starts at full cervical dilation and lasts until the fetus is

born. Finally, the third stage is the delivery of the placenta and placental membranes.

1.1.2 Pain during labor

There are indications that the pain parturients experience during labor is one of the

most intense pain experiences known. According to Melzack this feeling of pain is

only surpassed by the traumatic amputation of a digit or by the complex regional pain

syndrome. (2) During labor, pain increases as contractions increase in strength,

frequency and with advance of cervical dilation. For most patients, the zenith of pain

is reached right before full dilation. (3–5)

The pain originates from five separate

locations: the uterus, the lower segment of the

uterus, the cervix, the vagina and the

perineum. The thoracic segments T10-T12

and lumbar segment L1 innervate the uterus,

the distal uterus segment and cervical area.

Proximal vaginal innervation is mostly

identical to the innervation of the uterus and

cervical area, the distal part of the vagina and

perineum are innervated through the nervus

pudendus, originating from the sacral spine

segments S2-S4 (See figure 1).

The etiology of pain during labor is

multifactorial. There are parameters of the

delivery itself such as the stage and duration.

But also physical properties of the mother and

child, parity, weight, social-demographic

characteristics, ethnical background, attitude

towards labor and delivery, relatives,

surroundings and support from hospital staff

play a role. (6)

Pharmacological treatment available for labor pain roughly consists of three groups.

These are systemic opioids such as (remi)fentanyl and Meperidine (Demerol), inhaled

anesthetics such as nitrous oxide with oxygen (Entonox) and neuraxial blockades such

Figure 1: Schematic view of pain

pathways during labor. The T10-L1

segments innervate the uterus, distal

uterus segment and cervical area, where

pain is mostly felt during labor. The

nervus pudendus arises from the sacral

segments, innervating most of the vagina

and perineum where pain is mostly felt

during the delivery phase. RD Miller.

Basics of anesthesia, 6th edition.

Introduction 5

as epidural analgesia. Systemic opioids and epidural analgesia are both widely used

(7). Reviews have shown that epidural analgesia during labor is superior to systemic

opiate usage for analgesia and safety, for both mother and child. Inhaled anesthetics

such as nitrous oxide do have some analgesic properties, but are inferior to systemic

opioids and epidural anesthesia. (7,8)

1.2 Epidural anesthesia

1.2.1 Introduction to epidural anesthesia

Epidural analgesia (“an epidural”) is a central neuraxial block very suitable for

perinatal, intraoperative and postoperative analgesia. It can be applied at all levels of

the spinal cord with a single injection or with a catheter in the epidural space with

local anesthetic or in combination with, for example, an opioid.

1.2.2 Brief history

The first practitioners of epidural anesthesia were

Sicard (1872-1929) and Cathelin (1873- 1945)

who, in 1901, injected cocaine in the sacral hiatus

of their patients. Both doctors were unable to

provide epidural anesthesia at higher levels. In

1921 Pagés (1886-1923), a Spanish military

physician, was the first to use a blunt needle and

both acoustic and tactile feedback for puncturing

the ligamentum flavum. He died shortly after

publishing in a Spanish journal. His findings were

never translated or taught to an apprentice and

were forgotten. (9) In 1939 Dogliotti (1897-1966)

used local anesthetics for epidural anesthesia and

studied the spread of solutions in the epidural

space (See figure 2). He was the first to use the

“loss of resistance” technique to identify the

epidural space. His textbook describes using

continuous pressure on a syringe filled with saline

as the needle punctures through the ligamentum

flavum into the epidural space. (10) His method to

identify the epidural space is still being used

today.

1.2.3 Anatomy

The epidural space is an anatomical space surrounding the dura mater laterally,

anteriorly and posteriorly (See figure 3). Rostrally it is confined by the foramen

magnum and caudally by the ligamentum sacrococcygeum. Anteriorly it is limited by

the ligamentum longitudinale and posteriorly by the laminae vertebrae as well as the

ligamentum flavum connecting these laminae. It contains fatty and connective tissue,

lymphatic vessels, nerve roots, arteries and the epidural venous plexus. Every

vertebral level has its own sub-compartment, though liquids are usually able to

communicate freely through the entire epidural space. (9,11)

Figure 2: Drawing by Doglotti (10)

showing the “Periduralraum”, the

epidural space. Both the median (A)

and paramedian (B) approach are

shown. S.G: Spinal ganglion. Doglotti,

1939: Eine neue Methode der

regionären Anästhesie: Die peridurale

segmentäre anästhesie".

Introduction 6

The spread of any solution in the epidural space is not uniform and this might account

for occasional unpredictable results. (12) Contrary to popular belief, the nerve roots

found in the epidural space vary greatly in size across different individuals. This

might account for the large variation in block quality amongst different patients. (13)

While the sensory dorsal spinal roots are larger then the anterior motor roots, anterior

roots are easier to block. An explanation for this seemingly contradiction is the fact

that the sensory root is composed of a bundle of fibers, resulting in a far larger surface

area on which the local anesthetic works. (14)

1.2.4 Technique

For placement of an epidural catheter, a

needle with a lateral opening such as the

Tuohy needle is used. The patient is

placed in either the lateral decubitus or

sitting position. After identification of the

puncture spot for either median or

paramedian positioning, the needle with

mandarin (to prevent skin plugs being

lodged into the epidural space causing

epidermoid tumors) is inserted and placed

in the ligamentum flavum. In the lumbar

region this ligament is usually found 3.5–6

cm below the skin surface and is 4-6 mm

thick. On thoracic levels it is 3-5 mm

thick. Because the spinal cord ends around

the L1–L2 lumbar segment, there is a

theoretical risk for neurological damage

should there be an accidental dural puncture at thoracic height. In a retrospective

study of 4185 epidurals Giebler et al. found that thoracic epidural punctures are not

associated with an increase in neurological injury. (15) The increased angle of needle

insertion required for thoracic punctures is assumed to add an element of safety to

prevent dural punctures in thoracic epidurals. (9)

There are several ways to identify the epidural space (9). The loss of resistance

method features the use of constant pressure on a special air or saline-filled low-

friction syringe. When the needle enters the epidural space the fluid or air bubble

suddenly flows into the space without resistance. The hanging drop method can be

used because there is a sub atmospheric pressure in the epidural space. A drop of fluid

is placed in the hub of the needle and as the needle progresses through the

ligamentum flavum and thus enters the epidural space, the sub atmospheric pressure

sucks the hanging drop into the needle.

Technological innovations for the identification of the epidural space are also

available. One example is the acoustic puncture assist device, which uses a

continuous infusion to measure the pressure at needlepoint and emits a tone with its

frequency depending on the measurement. (16)

Figure 3: The epidural space and contents of

the dural sac shown at the level of the 4th

lumbar segment. The ligamentum flavum is

also shown posterior to the epidural space.

Millers Anesthesia, RD Miller, 7th edition.

Introduction 7

After the epidural space is identified a special catheter is inserted into the epidural

space as to be able to continuously administer local anesthetics with adjuvants. For

obstetric use the catheter should be inserted only 4-6 cm into the epidural space. (17)

1.2.5 Medication

After insertion of the catheter a small test dose is administered to assess a possible

intrathecal or intravenous catheter placement. Usually this is a small dose of lidocaine

with adrenaline. After administration the patient is monitored for signs of intrathecal

or intravenous injection. (18) Drugs used in epidural analgesia are local anesthetics of

which bupivacaine is the most commonly used. There are additives that can be

combined with local anesthetics to create a better or longer lasting effect or even a

quicker block onset. Commonly used additives are opioids, bicarbonate and alfa-2-

receptorantagonists. (6,19)

1.2.6 Epidural analgesia during labor

For obstetric use 0.0625%, 0.125% and 0.25% concentrations of bupivacaine are

used. A systematic review comparing epidural to systemic or no analgesia shows that

when opioids are used simultaneously a smaller dosage of local anesthetics is

required. (7) The chance of motor block is also reduced using lower concentrations of

the local anesthetic. A possible explanation for the lower required volumes for

obstetric use is the increased abdominal pressure and prominent epidural venous

plexus in parturients. The Dutch guideline for medical pain management during labor

suggests using bupivacaine 0.125% with 8-12 mL per hour continuous epidural

infusion. (6) Obesity, multiparity and more than 7 cm cervical dilation are associated

with a smaller chance of successful analgesia using an epidural. (20)

1.2.7 Complications

Epidural anesthesia during labor is possibly associated with a longer delivery phase,

greater chance of instrumental delivery, hypotension, urinary retention and motor

blockade. (6) Possible complications of an epidural puncture are accidental dural

perforation, intravasal or spinal catheter placement, systemic toxicity and in rare cases

epidural hematoma. Dural perforation resulting in a spinal positioning of the epidural

needle has an overall incidence of 0.5%. Should the epidural dosage of local

anesthetic be injected spinally this can result in a total spinal anesthesia. This is a

severe complication where the patient loses consciousness and ventilatory drive and

will be extremely hypotensive. With adequate support such as mechanical ventilation

and inotropics a complete recovery is likely. (19) Fortunately this complication is

extremely rare.

Introduction 8

1.3 Research question

The guideline for epidural anesthesia during labor in the Netherlands does not specify

at which spinal segment the catheter should be placed. (6) Textbooks usually specify

the L1-L5 segments. (9,11,19) Anesthesiologists are very reluctant to use a thoracic

segment to place an epidural catheter. This is mainly because the dura is thinner in the

thoracic region and the chance of a dural puncture might be greater. However, when

the physiology of pain during the first stage of labor is taken into account, choosing a

lumbar segment for epidural puncture seems illogical. The pain is described as

originating in the T10-L1 segments. In theory placing the catheter in this segment

should result in a better analgesia during this stage. In practice this remains unclear:

we found previous studies that differentiate in epidural puncture height and analgesic

qualities during labor.

In the Deventer Hospital both low-thoracic and lumbar epidurals are used for

analgesia during labor. Because only local anesthetics are used it can be expected that

after the initial bolus the area of analgesia would be the dermatomes according the

level of insertion, which are usually L1-L4. On this level, regular escape boluses are

needed. This is why some anesthesiologists insert the epidural catheter at a low

thoracic level. There has however, to our knowledge, never been a study that analyzes

if any difference between the level of analgesia between low thoracic and lumbar

epidurals for obstetric analgesia exists. This leads to our main research question,

which is formulated as follows: Does the height of the epidural catheter have an

effect on the quality of analgesia?

Hypothesis: “Taking the physiology of labor pain into account we hypothesized that

an epidural placed at a low thoracic segment should result in more stable analgesia

and thus needing less boluses during the first stage of labor. We also hypothesized

that a thoracic placed epidural catheter should result in less caesarian sections and

instrumental deliveries.”

The aim of this study is to assess whether there is a difference in quality of analgesia

between lumbar and low thoracic epidurals. Firstly a retrospective assessment of

epidural block height and primary labor outcome to determine whether the different

modalities show different incidence of caesarian sections or instrumental deliveries.

Secondly, to answer our main research question, the study tries to evaluate levels of

pain with both types of epidural, taking into account the number of rescue boluses.

Evaluating the pain proved impossible with the available retrospective data, so in

order to assess differences in levels of analgesia during the first stage of labor, a

prospective observational trial was set up.

Methods 9

2. Methods

2.1 Retrospective analysis

The retrospective assessment of epidural block height and primary labor outcome was

done to determine whether the different modalities show different incidences of

caesarian sections or instrumental deliveries. Unfortunately we could not gather

reliable information about the quality of the analgesia of these patients.

2.1.1 Data collection

A database of all epidurals performed and

registered by the anesthesiology department

of the Deventer Hospital between 1 January

2009 and 1 October 2012 was used. Data included

were the obstetric epidural itself and known epidural

puncture level. Also, a separate dataset from the

obstetrics department with information of all the

patients was acquired, containing labor start and

outcome, age of parturient, newborn weight, APGAR

score after 5 minutes, puncture time and delivery

time. To avoid human errors in database processing

an SQL script was written to combine the two

separate sets of data into a single database, using the

patient ID and procedure date as identifiers to match

cases. After combining these two datasets the data

were rendered anonymous by removing the patient

name and patient ID number. Excluded were

mismatches (punctures without accompanying labor, deliveries without epidural

puncture data), epidurals for abortions or miscarriages and double punctures.

2.1.2 Population and collected data

The datasets of the anesthesiology and obstetric departments contained 1245 and 1278

entries respectively. After exclusion the resulting dataset contained 1172 patient

entries usable for statistical analysis. (See figure 4) Of the 1172 patients total 96

received a low thoracic epidural and 1096 a lumbar puncture. The average age of the

patients was 29.8 years (17-46). All patients were female. See addendum A for the

table showing variables used in the dataset, data types and outcome possibilities.

2.1.3. Statistical Analysis

Statistical analysis was performed using SPSS 20 for Mac (IBM, 2011, RUG license).

The Pearson Chi-square test was used for nominal variables. For ordinal variables the

Mann-Whitney test was used and continuous variables were analyzed with the

Student T-test. The threshold used for statistical significance was a p-value of <0.05,

p-values between 0.05 and 0.1 were considered as trends.

Obstetric data n=1245

Anesthesiology data n=1278

Figure 4: Flowchart showing the

acquisition of the retrospective

database.

Matched by patient ID and procedure date. Excluded: - Entries with missing data

- Procedure mismatch - Multiple punctures

-Abortions/miscarriages

Final dataset, n=1172

Lumbar: n=1076 Thoracic: n=96

Methods 10

2.2 Prospective analysis

To assess differences in levels of analgesia between the two modalities during first

stage of labor the prospective study was set up.

2.2.1 Design

The aim of the prospective observational part of the

study was to assess levels of analgesia by different

epidural puncture levels. Being observational, this

study did not have any effect on the treatment the

women in labor received. After consulting the

medical ethics committee at the Isala Klinieken in

Zwolle and receiving a waiver showing no

objection, the observational trial started (See

addendum B through D for these documents).

Women receiving epidural analgesia during labor

were asked to participate in the study a short while

after placing the epidural. Upon verbal agreement,

written informed consent was acquired and patients

were included in the study.

Exclusion criteria were patient refusal to enter the

study, inability to give informed consent, epidural

analgesia in case of stillbirth or (medically

indicated) abortion, incomplete or unusable forms,

complications of the puncture or simultaneous use

of systemic opiate analgesia. Epidural puncture

level was solely dependent on the anesthesiologist performing the procedure. Both

delivery room staff and the patient were unaware of the level of the epidural catheter

making it a single-blinded non-randomized observational trial.

2.2.2 Measurements

After patients were included, the puncture level and patient ID were registered.

Lumbar epidural catheter placement was defined as the catheter being in the L1-5

segments, thoracic placement as T10-L1 segments. Back at the delivery room pain

scores were measured hourly by the delivery room staff using the Visual Analog

Scale (VAS). This is a validated, quick and easy to use rating scale suitable to

measure pain. (21,22) After delivery the patient’s file was studied for additional labor

and birth variables: APGAR, total labor time after the puncture, use of rescue boluses,

labor start and outcome.

2.2.3 Study population

During the study, a total of 57 women in labor received epidural analgesia (See figure

5). Three patients were not included because they had an epidural for medically

indicated abortion. Ten patients were unable or unwilling to provide consent. Of the

remaining 44 patients, 40 had usable escape-bolus data and 39 had VAS

measurements usable for analysis.

All epidurals performed during trial period: n=57

Usable for VAS analysis: n=39 Of which: Thoracic: n=11 Lumbar: n=28

Lumbar:

Failure to receive consent: n=10 Miscarriage/abortion: n=3

Unusable data: n=5 (VAS) n=4 (other parameters)

Figure 5: flowchart depicting the

algorithm used for inclusions in the

prospective study.

Total inclusions: n=44

Methods 11

2.2.4 Statistical analysis

Graphic representations include all measurements over time and averages per group

per hour. To compare VAS scores per hour between groups One-Way Analysis of

Variance (ANOVA) tables and T-tests were used, both are suitable to analyze VAS

scores. (23) All measurements between groups over time were analyzed with

Repeated Measures ANOVA.

Other mathematical operations performed to analyze the reported VAS scores were

slope calculation and comparing the maximum and minimal score measured per

patient. Thus reducing the series of measurements per patient to a single number and

enabling easier statistical analysis using the Student T-test.

Results 12

3. Results

3.1 Retrospective study results

Firstly the hypothesis that a difference in epidural segment puncture level could affect

the primary labor outcome was tested, see table 1.

3.1.1 Labor outcome

Of the 634 total spontaneous deliveries, 584 women received lumbar and 50 received

thoracic epidurals. No significant difference has been found in epidural catheter level

and the chance of spontaneous delivery (p=0.680).

Of the 271 caesarean sections, in 246 cases a lumbar epidural catheter was placed and

in 25 cases a thoracic epidural catheter. No significant difference in incidence of

caesarian section for the different epidural modalities was detected (p=0.479).

Because of the low incidence of instrumental deliveries all the instrumental deliveries

were first placed in one group. Resulting in a total of 267 entries, total, 246 of which

were lumbar and 21 of which were thoracic. No statistical significance was found for

the grouped instrumental deliveries (p=0.825).

Of all the instrumental deliveries 182 deliveries were vacuum extractions using a hard

cup, of those 182, 168 had a lumbar epidural and 14 were thoracic. No statistical

significance was found between the groups (p=0.789).

For both the 24 soft cup vacuum extractions and the 39 deliveries using obstetric

forceps, no significant differences were found. Complex deliveries requiring

professional help with the delivery of the head, shoulder or fundal expression had

such a small incidence that no reliable statistical analysis could be performed on the

acquired data.

Labor Outcome

Lumbar

(n= 1076)

Thoracic

(n=96)

Total

(n=1172) p-value

Spontaneous 584 50 634 0.680

C. Section 246 25 271 0.479

Instrumental 246 21 267 0.825

Vacuum (Hard cup) 168 14 182 0.789

Vacuum (Soft cup) 24 3 27 0.576

Forceps 39 2 41 0.431

Help w. head 3 0 3 0.604

Help w. shoulder 8 1 9 0.748

Fundus expression 4 1 5 0.335

Table 1: Labor outcome for all epidural catheters placed on lumbar and thoracic level. Instrumental

deliveries are first calculated as a single group and then divided into their subsequent types. None of the

results were significant (p<0.05).

Results 13

3.1.2 Height of the epidural and labor time

The labor after puncture time is the time in minutes

calculated from the epidural puncture itself until the

delivery. Whilst the mean time for thoracic

epidurals appeared slightly shorter, an independent

samples t-test was performed and revealed that

there was no significant difference in labor time

between thoracic (M=322.2 SD=189) and lumbar

(M=325.7 SD=195) placed epidurals (p=0.869).

3.1.3 APGAR score after 5 minutes

To analyze whether the APGAR score after 5

minutes differs amongst the lumbar and thoracic

epidural groups the Mann-Whitney test for ordinal

variables was used showing no significance

(p=0.710). See table 2 for the distribution of

APGAR scores per group.

APGA

R

Lumbar

(n=1076

)

Thoraci

c (n=96)

10 740 70

9 216 9

8 64 10

7 19 3

6 9 2

5 3 2

4 2 0

3 2 0

2 1 0

1 2 0

0 18 0

Table 2: APGAR score for all

epidural catheters placed on

lumbar and thoracic levels. No

APGAR scores <5 were recorded

for patients with thoracic placed

epidural catheters.

Results 14

3.2 Results of prospective study

Secondly the hypothesis that a difference

in epidural segment puncture level could

result into better pain relief during labor

was investigated.

3.2.1 Graphic representation

A parallel plot of all the VAS

measurements grouped by epidural

catheter level (“Spaghettigram”) revealed

no noticeable differences in VAS scores

(See addendum E).

Figure 6 shows the averaged VAS values

per group for the first five hourly

measurements. Looking at the first three

hours, both groups show increasing VAS

scores. The thoracic group appears to have

higher averaged VAS scores. After 3 hours less patients of the thoracic group are still

in labor (See section 3.2.2).

3.2.2. VAS score analysis

As the average remaining labor time after placing the epidural catheter in this study

was approximately 4.5 hours, pain scores per group were compared at every hour for

the first five hourly measurements, table 3. Whilst the graphical representation of the

average pain for both groups suggests that epidural catheter height does affect the

quality of analgesia, statistical analysis does not support this observation. Analysis

was performed using One-Way ANOVA.

Time

(hours)

Lumbar

(mean, SD, n)

Thoracic

(mean, SD, n)

p-value

1 M: 9.9, SD: 15.5, n=28 M: 9.5, SD: 18.2, n=11 0.945

2 M: 22.2, SD: 23.7, n=27 M: 23.5: SD: 21.9, n=11 0.879

3 M: 36.0, SD: 31.6, n=19 M: 39.3, SD: 31.9, n=10 0.788

4 M: 33.8, SD: 23.3, n=14 M: 39.3, SD: 14.5, n=4 0.686

5 M: 43.5, SD: 34.1, n=14 M: 54.5, SD: 14.9, n=2 0.667

Table 3: Mean and standard deviation (SD) of VAS pains scores per hour grouped

by lumbar, middle and thoracic epidural catheter placement. Measurements were

compared per time unit. Note the decrease in entries after t=3 for thoracic

epidurals. No significant results were found (p<0.05).

(p<0.05).

Figure 6: Plot of the averaged (per hour) reported

VAS scores during the first 5 hourly measurements.

Results 15

3.2.3 ANOVA for repeated measures

A better way to perform statistical analysis

for our model is the ANOVA test for

repeated measures. The VAS score, time

and the different groups are integrated

using this test. As there was a substantial

lower amount of measurements for the

thoracic group after 4 hours the repeated

measurements ANOVA were performed

using three different time windows. All

analyses started at t=1, the end points were

after 3, 4 and 5 hours respectively. The

post-hoc plot of the estimated marginal

means for VAS scores in the first three

hours for both groups for is shown in

figure 7. This plot takes into consideration

each mean in proportion to the unequal

sample size.

Analysis did show significant values for

within-subject tests showing that for both

groups, the VAS scores are affected by a

significant time effect. Between-groups tests checking for possible differences

between the separate groups were not statistically significant, as shown in table 4.

Time

window

Within-subjects

p-value

Between groups

p-value 1-3 < 0.001* 0.455

1-4 0.004* 0.898

1-5 0.08** 0.714

Figure 7: Plot showing the estimated marginal means

of the VAS score for the first three hours for thoracic

and lumbar epidural catheters. Both groups show an

increase of reported pain in time. No significant

differences between the groups were found.

Table 4: Results of Repeated Measures ANOVA to analyze the

different VAS scores amongst the two groups. Analysis performed

using three time windows (in hours). The within-subjects values

show that for the first two time windows the changes in VAS over

time are significant (*). In the third window a trend is visible (**).

Between groups no significant results were found (p<0.05).

Results 16

3.2.3. Inter-patient variables

One of the ways to check the difference in

analgesia between the two modalities is to look at

the highest, lowest and average VAS score for

every patient measurement series. The total

duration after receiving the epidural was also

calculated. Another variable worth interpreting

was the slope of the VAS measurements in

individual patients. The slope was calculated by

calculating the difference between the last and

first measurement divided by the total amount of

measurements, under the assumption that most

pain scores were increasing over time (See table

5).

No significant differences were found between groups for minimum, maximum,

average pain or slope. For the duration of labor after the epidural catheter placement a

trend was found towards thoracic epidurals being associated with shorter total dilation

time after the epidural procedure, see figure 8.

Measure p-value

Average VAS 0.564

Minimum VAS 0.771

Maximum VAS 0.680

Duration 0.076**

VAS Slope 0.219

Figure 8: The average VAS, duration and the VAS increase per hour. Figure 8a shows the thoracic group

having a lower average VAS than the lumbar group, though not statistically significant (p=0.564). In figure

8b we see that the duration of labor after the epidural procedure shows a trend towards being lower in the

thoracic group (p=0.076). The slope of the VAS score over time as seen in figure 8c is greater in the thoracic

group, but not significant (p=0.219).

Table 5: Statistical analysis of the

calculated measures between groups.

None of the results were significant

(p<0.05). However, there was a trend

showing the total labor time after

epidural catheter placement being lower

in the thoracic group (p=0.076).

a b c

Results 17

3.2.4 Escape boluses

Another method to measure the amount of pain in patients is to look at the amount of

requests for additional boluses of local anesthetic through the epidural catheter. In our

study a total of 20 patients (50%) asked for additional analgesia. As shown in table 6,

52% of the patients in the lumbar epidural catheter group requested more additional

analgesia, versus 45% in the thoracic group. This difference is not significant

(p=0.907).

3.2.5 Time until escape bolus requests

The period of time before patients requested

additional analgesia. Plotting the mean time until

requests for analgesia, patients in the thoracic group

appear to request more analgesia sooner than patients

from the other groups, figure 9). The lumbar group

requested after a mean time of 180 minutes, the

thoracic group after a mean of 162 minutes. However,

we found no statistical significance difference was

found (p=0.537).

Escape bolus None Once Twice Total

Lumbar 14 (48%) 10 (35%) 5 (18%) 29

Thoracic 6 (55%) 3 (27%) 2 (18%) 11

Total 20 13 7 40

Figure 9: The average time before

the patient requested additional

analgesia for both groups. The

differences are not significant.

Table 6: Cross tabulation showing escape bolus requests for both

epidural catheter levels. Of the 40 usable entries 20 patients

requested additional pain relief with the epidural catheter in situ.

The maximum amount of requests per patient in both groups was

two.

Discussion 18

4. Discussion

4.1 Main results

The aim of our study was to assess whether a difference in epidural puncture height

during labor would result in better analgesia and less instrumental assisted vaginal

births. Both our hypotheses that a thoracic placed epidural catheter would give better

pain relief during labor as well as less instrumental deliveries were not statistically

proven. While some trends were seen, no statistically significant results were found.

4.1.1 VAS Scores

We did not find any statistically significant differences in VAS scores in between

groups. Based on the visual representations of the measurements one could argue that

the lumbar group offers the best pain relief (see figure 6,7). Our study shows that the

average VAS for both groups appears higher than expected based on available

literature. (2,7,8,24) Besides the variation in epidural catheter segment level we

identified another deviation from regular practice in both groups that could cause this.

By request of the obstetricians the epidural infusion solution does not contain opioids,

despite the national guidelines for epidural analgesia during labor that recommend

doing so. (6)

4.1.2 Escape boluses

The use of escape bolus requests as a measure of pain is logical. If the parturient still

has pain despite the in situ epidural catheter, she asks for more analgesia. Therefore

we see these requests as a measure of acute pain. In our study, the amount of escape

bolus requests in the thoracic group (45%) is lower than in the lumbar group (52%).

This suggests thoracic placed epidurals offer better analgesia. However, taking into

account the time until the request for additional analgesia, the patients in the thoracic

group request escape boluses sooner. This is surprising, because one would expect the

group with the most requests for additional analgesia to have a shorter time until the

first request as well. An explanation can perhaps be found in the average VAS scores

as the thoracic group shows a greater increase in VAS over time while having shorter

total time. This does lead to the question if patients in the thoracic group would have

requested more escape boluses if their labor would have taken longer.

4.1.3 Other measures

After reducing all measurements for every patient down to one single value for easier

statistical analysis something interesting happened. Although not significant, the

average VAS score in the thoracic group was lower. This contradicts the hourly

averaged VAS graph we see in section 3.1.1 where the VAS scores in the thoracic

group are consistently higher. An explanation for this is found in the total time

measured. Some patients with a lumbar epidural had a longer total labor time in which

they also reached prolonged high VAS scores. Because they had high VAS scores for

a longer period the resulting average VAS per patient is greater. In our other analyses

this is not taken into account because we used small time windows such as the first

Discussion 19

three or four hours to ensure enough measurements in both groups for statistical

testing.

The difference in duration of labor remaining after puncture is interesting. In our

retrospective study we found no difference between the groups. In our prospective

study however, there is a visible trend towards thoracic placed deliveries being faster.

This could addressed to the small amount of patients we included with a thoracic

placed epidural catheter or because we did not adjust for other factors that could

speed up the dilation such as oxytocin use.

4.1.4 Caesarian sections and instrumental deliveries

It is known that the chance of an instrumental assisted vaginal birth (instrument

delivery) for parturients with an epidural is increased. (7) Our hypothesis that a higher

placed epidural catheter would result in better remaining motor function during the

expulsion phase and thus in less instrumental deliveries, was not proven. This might

be explained by the relatively small amount of patients with a thoracic epidural

puncture that required instrumental assistance, resulting in an underpowered statistical

analysis.

The incidence of spontaneous delivery and caesarian sections were also compared.

We did not find any significant differences. Were we to find a significant increase in

incidence of caesarian sections or decrease in spontaneous deliveries in the

retrospective study, continuing performing thoracic placed epidurals would be

questionable. Another finding by Anim-Somuah was that the APGAR score is equal

for both the groups with and without epidural analgesia. (7) Our results augment this

by showing that between the two epidural height modalities there is no difference in

APGAR score.

4.2 Results in relation to other studies

The fact that there are no other published studies about differences in epidural

segment level during labor could mean two things. Either there have never been

results interesting enough to publish or the difference has never been studied. In the

United States, for example, where more than 60% of all deliveries are with epidural or

spinal analgesia (25), it is hard to believe that variation of this basic parameter has not

been studied.

Whilst we could not find other studies about pain relief during labor via epidural

analgesia on thoracic and lumbar levels, there are studies that analyze transcutaneous

electrical stimulation (TENS) on thoracic and sacral levels for pain relief during labor.

These locations used in these trials are usually on the T10 and S2 segment, based on

the known pain physiology during labor. (26) A review by Francis (27) on TENS

during labor shows that, for it to be effective, the intensity has to be adjusted

according to the current pain. However, a recent review by Mello et al. shows there is

no evidence that it reduces the use of additional analgesics. (28)The Cochrane review

by Dowswell et al. also shows there is little evidence TENS provides adequate

analgesia. (26)

Discussion 20

4.3 Thoughts on the study

4.3.1 Design of the prospective study

The golden standard for medical research is a randomized controlled trial (RCT). For

the prospective part of our study this would have been our preferred study type.

However because of time restraints it was impossible to set up an RCT with full

medical ethics board approval in the relatively short time period available.

We avoided this by designing a prospective observational study in which we

successfully managed to measure patient pain as well as other variables such as

requests for additional analgesia in both lumbar and thoracic epidural catheter groups.

Because the study was not a double-blinded RCT, our design also introduced a degree

of bias: the administered treatment was not blinded nor randomized. The

anesthesiologist performing the procedure chose the level based purely on personal

preference.

4.3.2 Patient enrollment

The amount of patients that we managed to include for the observational trial was

smaller than expected. We identified multiple causes. Our estimation of the average

amount of epidurals per day could be erroneous. It was based on the patient numbers

in the retrospective study in which we found 1172 epidurals during 1369 days

resulting in ~0.86 per day. In our study we included 44 patients during the 70 days of

inclusion resulting in an average of ~0.63 per day. Based on our calculations we

expected to include around 60 patients. Unfortunately not every patient was able to

provide informed consent. This was mainly due to failure of the attending

anesthesiologist to get the patient to enroll in the study (n=10). Another possible

factor that was not taken into account is the seasonal nature of human birth that

traditionally shows fewer births during winter season. (29)

4.3.3 Measuring pain

How to measure something as subjective and elusive as pain has long been subject to

discussion. Today there are numerous variants of scores that can be used for this

purpose but there is still no consensus for a “standard” measure (30)if one would exist

at all. The visual analog scale (VAS) has been widely used in a diverse adult

populations to evaluate different kinds of pain.(22),

Research evaluating the VAS originates mostly from social sciences. Because of its

historic use, we “automatically” assumed it would be the best score suitable for our

study. However, recent literature shows that both the numeric rating scale (NRS) and

VAS are evenly matched for acute pain. (14,31,32) In our study however, we used the

VAS and dedicated VAS rulers to measure it.

To assess the quality of an epidural block not only the amount of analgesia is

important but the height or spread of the block as well. It is regrettable (but

comprehensible) assessing dermatome height is an accurate and time-consuming

activity that requires patience and accuracy, for which there is no place in the delivery

room. The interval of measuring the VAS score is subject to discussion as well. We

chose to measure pain using the VAS by the hour. Smaller time intervals between

Discussion 21

measurements were preferable, but because of logistic reasons we chose to add the

VAS measurement to the nurses’ series of vital sign measurements. Our VAS

measurement started 1 hour after placing the epidural catheter. If we were to re-design

our study we would have added a VAS check before leaving the anesthesiology

department to establish a baseline for future measurements. Another important factor

we did not measure was the patient satisfaction about pain relief during labor. This

could have given a good indication about whether the analgesia was adequate during

the entire labor process.

4.3.4 Parity

One aspect we did not take into account was the parity of the parturients receiving an

epidural. It is known that women who have their first delivery (nulliparae), experience

the most pain during the first phase of the delivery. (2,4)In the Deventer Hospital the

obstetricians have a policy of mostly proposing epidural analgesia as pain relief to

nulliparae. This might also explain why parturients in both our study groups appear to

show more pain than expected based on available literature. In our study we did not

look at possible differences between multi and nulliparae because it would make the

groups available for statistical analysis even smaller whilst also introducing bias in

patient selection.

4.3.5 Sacral roots, sacral sparing

Taking into account the physiology of labor pain, it seems logical that placing a

thoracic epidural results in better analgesia during the first phase of labor. However,

during the second phase most pain is caused by pressure on the vaginal wall and

perineum, both of which are innervated by the nervus pudendus originating from

sacral nerve roots. (2) In lumbar epidurals sometimes a phenomenon called sacral

sparing occurs: a reduced effect of the local anesthetics in the sacral region. (33) It

remains unclear if a thoracic placed epidural catheter results in a difference in

analgesia during this the second phase, as we did not measure analgesia during the

delivery itself.

4.3.6 Epidural catheter location and epidural space fluid dynamics

As mentioned in our introduction, the location where the epidural catheter eventually

ends up is subject of discussion. In a radiological analysis Beck has shown that even

though the epidural catheter is expected to assume a cranial position only 48% of

catheter tips did end up in a cranial position, 9% caudal and 43% was still near the

insertion site. (34) This makes the assumed location of the epidural catheter somewhat

questionable. However, with current techniques and materials this is the best result

achievable.

It is known that the distribution of the local anesthetic in the epidural space is non-

uniform and difficult to predict. (9,12,13) Additionally, for pregnant women the

distribution is also affected by engorgement of the epidural venous plexus resulting in

increased pressure in the epidural space. (9) Compared to normal physiology a

smaller volume of solution might result in equivalent spread.

Another point of discussion is whether there is an actual difference between the

maximum heights reached by the injected solution between the two epidural groups. It

Discussion 22

is known that epidural infusions tend to migrate to higher thoracic segment levels.

(9,19) Taking this into account, perhaps it would have been wise to have used smaller

solution volumes for the thoracic epidurals. This would be to avoid injecting so much

volume in the epidural space that any difference made by diversifying the puncture

location is nullified by the wash of solution injected. We acknowledge that future

research towards better understanding of the behavior of solutions in the epidural

space in both parturients and normal patients is invaluable.

4.3.7 Complications

As Sprigge and Harper show in a survey of 18333 epidural punctures, the chance of

an accidental dural perforation is 0.91%. (35) In our prospective study no dural

punctures were recorded in either group. In the Deventer Hospital delivery rooms it is

custom to disable the continuous epidural infusion once the expulsion phase begins

and the parturient has to push. In the past, motor function was often completely

blocked rendering the women unable to do so. This was most likely due to high

concentrations of local anesthetic. In our study only one block was described as too

high, remarkably in the group with lumbar punctures. An explanation might be found

within the individual patient characteristics such as the body mass index. No complete

motor blocks during the delivery phase were registered. There were no other

anesthesia-associated complications in the study.

4.4 Clinical implications

Our results show a few trends in favor of thoracically placed epidurals and some in

favor of standard lumbar epidurals. But they are inconclusive overall. While the local

anesthesiologists acknowledge that there appear to be certain advantages in using a

thoracically placed epidural, the current standard treatment will probably not change

until more proof is found that epidural catheters on a thoracic level provide better pain

relief during labor.

A possible way for this is continuing the current prospective study. But as mentioned

above, there are downsides to not having a full-fledged RCT. We advise starting a

continuation of this study where patients are randomized between T10-L1 and L1-L5

segment punctures. Because of the relatively small amount of requests for epidural

anesthesia during labor in the Deventer Hospital, it might be wise to involve multiple

other hospitals to reach acceptable inclusion numbers.

Conclusion 23

5. Conclusion

Epidural analgesia is a safe, effective and reliable method of pain relief during clinical

deliveries.

We were unable to verify our hypothesis that thoracic epidural anesthesia during the

first phase of labor results in better pain relief and less instrumental deliveries. We

found no significant difference in analgesia using VAS scores reported by parturients

with epidural catheters on lumbar or thoracic levels. The number of escape boluses

was higher in the group with lumbar placed epidural catheter, though not statistically

significant. The thoracic group requested escape boluses considerably sooner than the

lumbar group.

In our study, the difference in puncture height of the epidural catheter did not affect

the incidence of spontaneous delivery, caesarian sections or instrumental deliveries.

APGAR scores of the newborn were not significantly different. The labor time after

the epidural puncture was shorter for patients in the thoracic group during the

prospective study, though we did not see this difference in the retrospective study.

More research is needed to further objectify the difference in pain relief by thoracic

and lumbar epidurals and the properties of fluids injected the epidural space before

clinical practice will change.

References 24

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Acknowledgements 26

7. Acknowledgements I would like to thank my mentor, Jan-Hein Cobben for his help in devising the study

subject as well as his help during the process of designing, collecting data and writing

the report. Secondly I would like to acknowledge the assistance of all the

anesthesiologists in the Deventer Hospital for their work to include patients.

My gratitude for the gynecologists for their help setting up the study and most

important of all, I would like to thank the delivery room staff for their valuable help

with the measurements, without them the study would not have been possible.

Finally I would like to thank my colleagues for all their support, help with

proofreading, valuable insights and all the coffee breaks.

Jon Gutteling

Deventer,

March 28, 2013

Addendum 27

ADDENDUM

Table of Contents

A. Database parameters ........................................................................................................ 28

B. Ethics board waiver .......................................................................................................... 29

B: Patient information letter ................................................................................................ 30

B: Consent form ..................................................................................................................... 33

C. “Spaghettigram”/ Parallel VAS plot ............................................................................... 34

Low thoracic versus lumbar epidural anesthesia during the first phase of labor

Addendum 28

A. Database parameters

Name Type Possibilities

IP Code/String Age Continuous In years

Date Unix time stamp Level Dichotomous 0 = Lumbar, 1 = Thoracic

VAS* Ordinal 0-100, per hour

Escape bolus* Scale Amount of requests

Escape bolus- time* Continuous In minutes

Start of labor Categorical 1 = Spontaneous contractions

2 = Spontaneous rupture membranes

3 = Spontaneous contractions + rupture of membranes

4 = Stimulation after spontaneous rupture of membranes

5 = Amniotomy

6 = Chemical

7 = Amniotomy + chemical

End point Categorical 1 = Spontaneous partus

2 = Caesarian section

3 = Vacuum extraction (hard cup)

4 = Vacuum extraction (soft cup)

5 = Forcipal extraction

6 = Other

Time Continuous In minutes

APGAR 5 Ordinal 0-10

Gemelli Dichotomous 0,1

Addendum 29

B. Ethics board waiver

Addendum 30

C: Patient information letter

(According to CCMO model letter)

Onderzoek naar verschil in effect van hoge en lage ruggenprik

tijdens de bevalling

Deventer, 25-09-2012

Geachte mevrouw,

In het Deventer ziekenhuis doen wij medisch-wetenschappelijk onderzoek naar welke

methode van ruggenprik de beste pijnbestrijding geeft tijdens de ontsluitingsfase van de

bevalling. Wij vragen u vriendelijk en vrijblijvend om mee te doen aan dit onderzoek.

Om een weloverwogen beslissing te kunnen maken vragen wij u om deze informatiebrief

en de algemene brochure rustig door te lezen en te bespreken met uw naasten.

Als u na het lezen van deze informatie nog vragen heeft kunt u contact opnemen met de

onderzoeker of met een onafhankelijke arts. Op bladzijde 3 vindt u de contactgegevens.

Misschien dat u het gevoel heeft dat u op dit moment niet in staat bent een

bewuste/weldoordachte keuze te maken. In dat geval kunt u altijd achteraf (na uw

bevalling) aangeven dat uw gegevens uit het onderzoek verwijderd moeten worden.

Wat is het doel van het onderzoek? Door dit onderzoek krijgen artsen een beeld van welke soort ruggenprik de beste

pijnbestrijding geeft tijdens de ontsluitingsfase van de bevalling. Dit heeft mogelijk

gevolgen voor de manier waarop toekomstige patiënten behandeld worden. Wij zijn

vooral geïnteresseerd in mate van pijnstilling na de ruggenprik.

Welke behandeling wordt onderzocht? Wij onderzoeken of de hoogte van de ruggenprik invloed heeft op de mate van pijn die u

ervaart. In het Deventer Ziekenhuis worden twee verschillende hoogtes (onderrug of

hoger) met goed resultaat gegeven. Deze hoogte hangt af van de voorkeur en ervaring

van diegene die prikt.

Hoe wordt het onderzoek uitgevoerd? Alle vrouwen die tussen 1 december 2012 en 1 maart 2013 tijdens de ontsluitingsfase van

de bevalling een ruggenprik krijgen, zullen worden gevraagd om mee te doen aan dit

onderzoek. De onderzoeker of verpleegkundige zal bij iedereen die een ruggenprik heeft

gekregen elk uur een pijnscore afnemen.

Wat wordt er van u verwacht? Meedoen met dit onderzoek zal voor u betekenen dat er na het krijgen van de ruggenprik

Addendum 31

elk uur iemand langskomt op de verloskamer. Dit kan de hoofdonderzoeker zijn of een

verpleegkundige. Deze persoon zal u vragen hoeveel pijn u op dat moment ervaart. Dit

zal gebeuren met een speciale pijnlineaal, waarop u aanwijst hoeveel pijn u heeft. Dit

kost ongeveer één minuut per keer.

Wat is er meer of anders dan de normale behandeling? U krijgt de normale behandeling: een ruggenprik in de onderrug of hoger. Deze hoogte

hangt af van de voorkeur en ervaring van diegene die prikt. Het onderzoek heeft geen

invloed op de soort behandeling die u krijgt. Het onderzoek betekent voor u dat er na het

krijgen van de ruggenprik een onderzoeker langskomt om te vragen hoeveel pijn u heeft.

Wat zijn de mogelijke voor- en nadelen van deelname aan dit onderzoek? U heeft zelf geen voordeel van deelname aan dit onderzoek. Voor de toekomst kan het

onderzoek wel nuttige gegevens opleveren.Het nadeel is dat er tijdens de bevalling een

aantal keer iemand komt vragen hoeveel pijn u heeft.

Wat gebeurt er als u niet wenst deel te nemen aan dit onderzoek? U beslist zelf of u meedoet aan het onderzoek. Deelname is vrijwillig. Als u besluit niet

mee te doen, hoeft u verder niets te doen. U hoeft niets te tekenen. U hoeft ook niet te

zeggen waarom u niet wilt meedoen. U krijgt de behandeling die u anders ook zou

krijgen. Als u wel meedoet, kunt u zich altijd bedenken en toch stoppen. Ook tijdens het

onderzoek.

Wat gebeurt er als het onderzoek is afgelopen? Deelname aan het onderzoek eindigt na uw bezoek aan het Deventer Ziekenhuis.

Deelname aan het onderzoek wordt voortijdig beëindigd indien u dit zelf besluit of de

onderzoeker het noodzakelijk acht omdat uw veiligheid of gezondheid in gevaar is. Er

zijn geen risico’s aan tussentijdse beëindiging van het onderzoek voor uw gezondheid.

Uw gezondheid loopt geen gevaar als het onderzoek tussentijds beëindigd wordt.

Bent u verzekerd wanneer u aan het onderzoek meedoet? Omdat de behandeling bij dit onderzoek niet afwijkt van de normale behandeling is er

géén aparte verzekering afgesloten. U valt onder de normale verzekering die u en het

ziekenhuis hebben afgesloten.

Wat gebeurt er met uw gegevens? Uw gegevens zijn vertrouwelijk en zullen anoniem worden verwerkt. Alleen de

informatie die van belang is voor het onderzoek zal worden bekeken. Uw privacy en

medische gegevens zullen volgens de geldende regels worden behandeld en bewaakt. De

resultaten van de vragenlijsten worden in een computerbestand opgeslagen. Gegevens

zoals uw naam en geboortedatum worden vervangen door een codenummer. Alleen dat

codenummer zal worden gebruikt in documentatie of rapporten over dit onderzoek.

Alleen de hoofdonderzoekers weten welke code u heeft. Alle formulieren waar uw

persoonsgegevens op staan worden na afloop van het onderzoek vernietigd. De

hoofdonderzoeker kan bij een vervolgonderzoek uw gegevens terughalen via een

bepaalde “sleutel”.

Addendum 32

Zijn er extra kosten wanneer u besluit aan dit onderzoek mee te doen? Er zijn geen extra kosten verbonden aan deelname aan dit onderzoek.

Welke medisch-ethische toetsingscommissie heeft dit onderzoek

goedgekeurd? In overleg met toetsingscommissie Isala Klinieken Zwolle is besloten dat het onderzoek

niet medisch ethisch getoetst hoefde te worden. Wel zijn deze informatiebrief en het

toestemmingsformulier geaccordeerd door de METC.

Wilt u verder nog iets weten? Voor vragen kunt u altijd contact opnemen met hoofdonderzoeker: Dhr. J. Gutteling via

e-mail (gutteling@dz.nl) of telefonisch (0570-53 53 53 doorverbinden met nummer

2869). De onafhankelijk arts is P.J.Q. van der Linden, gynaecoloog. Bereikbaar via

email: p.j.q.vanderlinden@dz.nl.

Bij klachten voor, tijdens of na het onderzoek, kunt u contact opnemen met de

klachtencommissie van het Deventer Ziekenhuis via tel: 0570 – 53 61 44.

Bijlagen:

Algemene brochure medisch-wetenschappelijk onderzoek met mensen

Toestemmingsverklaring

Met vriendelijke groet,

Dhr. J. Gutteling

Hoofdonderzoeker:

J. Gutteling BSc, Afdeling Anesthesiologie

Deventer Ziekenhuis

Nico Bolkesteinlaan 75

7416 SE Deventer

Tel: 0570-53 53 53 intern 2869

e-mail: gutteling@dz.nl

Begeleider:

Dr. J.M.G. Cobben, Anesthesioloog

Deventer Ziekenhuis

Nico Bolkesteinlaan 75

7416 SE Deventer

Addendum 33

D: Consent form

(According to CCMO model consent form)

Addendum 34

E. Parallel plot of VAS (“Spaghettigram”)