A Prospective Audit of Regional Anaesthesia Failure in 5080 Caesarean Sections

8/21/2019 A Prospective Audit of Regional Anaesthesia Failure in 5080 Caesarean Sections

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A prospective audit of regional anaesthesia failure in 5080 Caesarean sections*

Author(s):Kinsella, S. M.

Issue: Volume !"8#, August $008, p 8$$%8!$

Publication

Type:&'riginal articles(

Publisher: ) $008 Association of Anaesthetists of reat +ritain -reland

Institution(s):

Consultant Anaesthetist, epartment of Anaesthesia, St Michael/s ospital, +ristol

+S$ 81, 2K

Accepted3 $4 anuar6 $008

Stephen Michael Kinsella 17mail3 stephen.insella9u:ht.nhs.u

*ata presented in part at the ':stetric Anaesthetists/ Association annual scientific

meeting, ;ondon $005.

A:stract

Ringkasan : Anestesi untuk operasi caesar telah diaudit selama 5 tahun : 5080kasus dilakukan dengan menggunakan tulang belakang 63 % , epidural top -up 26 % , dikombinasikan spinal - epidural 5 % dan anestesi umum primer 5 % !ingkat kon"ersi anestesi umum anestesi regional adalah 0,8 % untuk elekti#dan $, % untuk bagian darurat caesar dibandingkan dengan Ro&al 'ollege o#

(okter-dokter anestesi target ) % dan 3 % !ingkat kon"ersi regional untukanestesi umum dalam kategori ) operasi caesar adalah 20 % *eban&ak 8 %+anita memiliki anestesi umum ketika kedua enderal utama dan kon"ersianestesi regional digabungkan !ingkat kegagalan untuk mencapai operasibebas rasa sakit adalah 6 % dengan spinalis , 2$ % dengan epidural top - updan )8 % dengan kombinasi spinal - epidural *elain enis anestesi danurgensi operasi , #aktor lain &ang berhubungan dengan kegagalan pra-operasanestesi regional termasuk indeks massa tubuh , tidak ada operasi caesarsebelumn&a , dan indikasi untuk caesar ga+at anin akut atau kondisi medis

ibu emadain&a blok anestesi pra-operasi dan durasi operasi adalah #aktorrisiko penting bagi kegagalan intra - operati# .ntuk anestesi spinal ,penggunaan opioid spinal dikaitkan dengan kegagalan kurang pra-operasi .ntuk anestesi epidural top -up , "olume &ang top - up epidural lebih rendahdikaitkan dengan kegagalan kurang pra-operasi , dan penggunaan adrenalindikaitkan dengan keduan&a kurang kegagalan pra-operasi dan intra - operati#

!ingkat insiden buruk berat adalah ) : )26 dengan anestesi umum dan ) : 50dengan anestesi regional


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istor6

unct

are not used routinel6 :ecause of concerns a:out maternal pulmonar6 aspiration and fetal effects.

?he percentage use of general anaesthesia for Caesarean section has :ecome a marer of the =ualit6

of the o:stetric anaesthetic service &4%!(. As the overall use of general anaesthesia has declined,

urgenc6 of Caesarean section and failure of regional anaesthesia have :ecome the main indications &@(. A four categor6 classification of Caesarean section urgenc6 as descri:ed in $000 ith the aim of

improving audit data collection in comparison to the :inar6 electiveBemergenc6 classification &5(.

ailure of regional anaesthesia is defined in several a6s. ':>ective outcomes include conversion to

general anaesthesia &@, , D(, conversion to an6 different form of anaesthesia &@, 8(, or pain during

surger6 &E, 40(. -n research studies of epidural top7up solutions here onset time is the primar6 end7

point, failure ma6 :e defined as the ina:ilit6 to achieve a defined degree of nerve :loc suita:le for

Caesarean section &44, 4$(. ?hese studies have not esta:lished an ideal top7up solution.


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pro:lems at successive stages of the esta:lishment and management of the anaesthetic "AppendiF#.

?he definition of a satisfactor6 regional anaesthetic :loc for Caesarean section as the loss of cold

sensation, using eth6l chloride spra6, from ?@ "the nipples# don to S5 "the :uttocs#, as ell as

anaesthesia "no feeling# to a 4E gauge needle inserted at several points along the line of surgical

incision at ?4$. Gain during the operation as split into mild or severe, :ased on a cut % off for mild

pain of up to 4 mg alfentanil or 400 Hg fentan6l, and the use of onl6 one t6pe of analgesia.

-nitiall6, data ere collected onl6 on Caesarean sections under regional anaesthesia. Starting on 4st

une $000 "Iear $#, all Caesarean sections that had primar6 general anaesthesia ere also logged

using a separate audit num:ering se=uence. ?he indication for the use of general anaesthesia as

included on the data form.

?he urgenc6 of Caesarean section as classified using a 57point scale in Iear 4 and a @7point scale

from Iear $ &5(. ?he urgenc6 grade in Iear 4 cases has :een converted to the e=uivalent @7point scale

:6 com:ining the original grades $ and ! &5(.

Spinal anaesthesia as the preferred method and the use of the right lateral position for insertion a

encouraged. ?he standard dose as $.5 ml h6per:aric :upivacaine 0.5J ith !00 Hg diamorphine.

Spinal fentan6l as occasionall6 used, especiall6 for more urgent cases. hen an epidural as used

for analgesia during la:our, it as usuall6 topped7up for Caesarean section. ?he drugs used to top up

ere not standardised. ?hese ere :upivacaine and lidocaine, to hich might :e added adrenaline 5

Hg.ml74 "4 3 $00 000#, sodium :icar:onate 8.@J, fentan6l or diamorphine. ;aevo7:upivacaine :ecame

availa:le toards the end of the audit period. CS1 and microspinal catheters ere reserved for

compleF cases, such as those that re=uired slo onset of the regional :loc, omen ith anatomicaldifficulties or hen prolonged surger6 as anticipated. eneral anaesthesia as discouraged unless

specificall6 indicated. -f accidental dural puncture occurred during la:our, the epidural catheter as

sometimes inserted into the spinal space in order to use it for la:our analgesia.

Statistical anal6sis as performed to investigate factors associated ith pre7operative or intra7

operative failure. Gre7operative failure as defined as conversion to another anaesthetic :efore the

operation started or failure to achieve a satisfactor6 :loc "as defined a:ove#. -ntra7operative failure

as defined as unsatisfactor6 anaesthesia that re=uired analgesia &40(. ?his eFcluded cases here

conversion to another anaesthetic had :een performed :efore surger6.

?he anal6sis as carried out initiall6 on all regional anaesthesia cases. 2nivariate anal6sis of factors

that might influence pre7operative failure as performed first using chi7s=uared tests. actors from

the audit data:ase included audit 6ear, t6pe of anaesthesia, la:our epidural in place :ut not topped

up, indication for Caesarean, hether the oman as in la:our and Caesarean urgenc6. ata from th

la:our ard o:stetric data:ase included height, eight at :ooing, :od6 mass indeF "+M-#, gestation

parit6, num:er of previous Caesarean sections, neonatal eight and decision7deliver6 interval.

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orards and :acards stepise logistic regression anal6sis as then used to determine hich

factors ere significant predictors of the outcome. A p value L 0.05 as used to define statistical

significance. ?he same process as repeated for intra7operative failure, :ut including the factors

:loc ade=uate pre7operativel6/ and duration of surger6.

?he same anal6sis as performed on the su:7groups of omen ith spinal and epidural top7up

anaesthesia. -n the spinal group, factors specific to this t6pe of anaesthesia ere also includedN theseere insertion position, indication for position if sitting "change from lateral, o:ese, preference of

the anaesthetist, otherBunnon#, position after insertion, local anaesthetic volume and use of spina

opioid. -n the epidural top7up group, the specific anaesthetic factors included ere t6pe of local

anaesthetic ":upivacaine, lidocaine, 50 3 50 :upivacaine3lidocaine, and other/ including laevo7

:upivacaine and non7standard local anaesthetic miFtures#, volume of local anaesthetic, use of

adrenaline, use of :icar:onate and dose of epidural opioid "including Oero dose#.


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igure 4 lo diagram of spinal management. A successful spinal is one that as used for Caesarean

section ith no intra7operative discomfort. &;A, local anaestheticN A, general anaesthesia,


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igure $ lo diagram of top7up epidural management. A successful epidural is one that as used for

Caesarean section ith no intra7operative discomfort. &;A, local anaestheticN A, general

anaesthesiaN


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igure ! lo diagram of com:ined spinal7epidural "CS1# management. A successful CS1 is one that

as used for Caesarean section ith no intra7operative discomfort. &;A, local anaestheticN A,

general anaesthesiaN


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conversion as pre7operative in 8!J categor6 4 spinals and E0J categor6 4 top7up epidurals, in

contrast to pre7operative conversion in 8J of all spinals and 8J of all top7up epidurals.

?a:le 4 -ndications for Caesarean section and indications for primar6 general anaesthesia. ?hese tota

are P 400J as multiple indications could :e assigned.

?a:le $ Caesarean section urgenc6, t6pe of primar6 anaesthesia and conversion of regional anaesthesi

to general anaesthesia during 6ears $%5.

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Most of the omen having a categor6 4 operation "8!J# and categor6 4%! operation "D5J# ere in

la:our.

?here ere 40 cases in hich an epidural had :een esta:lished during la:our :ut as not topped up

for Caesarean section. ?he ma>orit6 of these ere not topped up :ecause of poor =ualit6 :loc, :ut

other reasons included epidural catheter misplaced or disconnected, epidural onl6 recentl6 inserted,

lac of time for top up, maternal anFiet6 and previous accidental dural puncture. 'f these 40

patients, 8 had a primar6 regional :loc for Caesarean section and $0 had general anaesthesia3 4 fo

urgenc6 and four for maternal preference.

?o cases ith an epidural catheter placed spinall6 after accidental dural puncture had unrelia:le

analgesia during la:our and there as no attempt to top up the intrathecal catheter/. Grimar6 spina

anaesthesia as planned, :ut in one case the spinal could not :e located and general anaesthesia a

given.

?a:le ! shos the num:er of omen having intraoperative pain and conversion of regional anaesthesi

to general anaesthesia related to the ade=uac6 of :loc :efore surger6.

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?a:le ! -ncidence of pain and intra7operative conversion to general anaesthesia depending on

ade=uac6 of :loc :efore surger6 in @5@0 cases using regional anaesthesia.

Critical incidents

A :oF asing for reporting of critical incidents as added to the data collection form from regional

anaesthesia case no 4!00 "general anaesthesia case num:er @@#. ?hese are presented in decreasing

order of seriousness3

Grimar6 general anaesthesia

* Categor6 4N initial attempt at intu:ation failed, mas ventilated :efore further successful attempt.

Grimar6 general anaesthesia ith la:our epidural esta:lished :ut not topped up

* "regional anaesthesia pro:lem# categor6 !N intravenous epidural catherN epidural ineffective and

top7ups go to m6 head/.

Conversion of regional anaesthesia to general anaesthesia

* Categor6 !N epidural top7up for failure to progress in la:our in a pre7eclamptic omanN pain onentering the peritoneum, general anaesthesia conversion folloed :6 :ronchospasm and pulmonar6

oedema re=uiring -?2.

* Categor6 $N acute fetal distress after eclampsia, CS1 attempt produced inade=uate :loc, pre7

operative general anaesthesia as folloed :6 persisting h6poFaemia and h6potension, transferred to

-?2.

* Categor6 $N maternal distress a:out sensation of spinal :loc, pre7operative general anaesthesia

conversion and failed intu:ation at first attempt.

* Categor6 @N failure to site spinalN general anaesthesia conversion, endo:ronchial intu:ation ith

desaturation, :rad6cardia and h6potension.

* "regional anaesthesia pro:lem# categor6 @N inade=uate spinal re=uired general anaesthesia

conversion :efore deliver6, as6stole during peritoneal stretching.


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:upivacaine $0 ml and fentan6l 400 HgN decreased consciousness ensued and general anaesthesia as

induced.

* Categor6 $N fetal distress, standard spinal insertion, patient developed severe pain after deliver6 :u

refused general anaesthesia, agreed to epidural hich as performed in the lateral position, once

esta:lished surger6 proceeded painlessl6 "counted as general anaesthesia conversion in totals#.

* Categor6 @N pulmonar6 oedema after deliver6 in a oman ith severe aortic stenosis having lo dos

CS1.* Categor6 @N spinal, as6stole folloing sin incisionN several 6ears :efore she had an almost identical

episode during her first Caesarean section.

* Categor6 $N spinal misplacement of epidural doseN a ! ml test dose of 0.5J :upivacaine and 4 3 $00

000 adrenaline ith D.5 Hg fentan6l produced a C5 :loc ith arm eaness.

* Categor6 !N epidural top7up for failure to progress, transient drosiness and unresponsiveness durin

surger6 responded to naloFone.

* Categor6 !N :lood aspirated from epidural catheter after 5 ml of top7up had :een givenN spinal

inserted for operation.

-n addition to these cases, there ere siF high :locs ith respirator6 pro:lems, three high :locs

ith arm eaness, siF high :locs, three :rad6cardias, 40 h6potensions, three supraventricular

taFch6cardias, five non7anaesthetic drug or lateF reactions and three miscellaneous.

uring this period, there ere 45E primar6 general anaesthetics and E! regional anaesthetics

converted to general anaesthesia. ?here ere five critical incidents "to serious# associated ith

general anaesthesia, all :ut one in cases of general anaesthetic conversion. ?he rate of incidents as

$J. ?here ere 54 incidents "seven serious# related to the regional anaesthesia in !50 regional

anaesthetics, a rate of 4.@J.

uring the period that critical incidents ere recorded, 8 cases had a spinal anaesthetic in the

presence of an epidural that had not :een topped up for Caesarean section. Mean volume of

h6per:aric :upivacaine 0.5J as $.@ ml &range 4.5%$.5 ml(. 'ne high sensor6 :loc "?4# as noted. -n

D4 cases ith an epidural that as apparentl6 in the correct space :ut failed to produce an ade=uate

:loc for Caesarean after :eing topped7up, a spinal anaesthetic as given. Mean volume of h6per:ar

:upivacaine as 4. ml &range 4.0%$.5 ml(. Seven high sensor6 :locs ere noted, ranging from C! to

C8 here documented. ive of these ere accompanied :6 d6spnoea and one :6 hand eaness. -nthree of the D4 cases, the spinal in>ection as apparentl6 made into the correct space :ut did not

produce an6 change in :loc, possi:l6 :ecause it as made into the epidural space containing local

anaesthetic rather than the su:arachnoid space.

Statistical anal6sis

2sing univariate anal6sis, there as no effect on failure rate of audit 6ear and epidural drugs

including local anaesthetic, opioid or :icar:onate. ?here as a significant effect of epidural


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adrenaline on the ris of :oth pre7operative and intra7operative failure, and spinal insertion position

on the ris of pre7operative failure. urther statistical results are availa:le from the author. ?he

results of the logistic regression anal6ses are shon in ?a:les @%.

?a:le @ ;ogistic regression anal6sis of factors associated ith regional anaesthesia failure. Gre7

operative failure includes conversion to another anaesthetic or failure to achieve a satisfactor6 :loc

intra7operative failure includes unsatisfactor6 anaesthesia that re=uired treatment.

?a:le 5 ;ogistic regression anal6sis of factors associated ith spinal failure. Gre7operative failure

includes conversion to another anaesthetic or failure to achieve a satisfactor6 :locN intra7operative

failure includes unsatisfactor6 anaesthesia that re=uired treatment.

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?a:le ;ogistic regression anal6sis of factors associated ith epidural failure. Gre7operative failure

includes conversion to another anaesthetic or failure to achieve a satisfactor6 :locN intra7operative

failure includes unsatisfactor6 anaesthesia that re=uired treatment.

iscussion

?his audit o:served the anaesthetic practice in a large teaching hospital. ?he overall use of

anaesthetic techni=ues in the 576ear period "general anaesthesia 5J, spinal !J, epidural top7up $J

CS1 5J#, is not dissimilar to national data from $00@ "general anaesthesia 44J, spinal 55J, epidural

$0J, CS1 40J# &4@(, although the general anaesthesia rates are not strictl6 compara:le as the nationa

data ma6 include cases of failed regional :loc.

Qational standards for rate of regional anaesthesia and conversion of regional anaesthesia to general

anaesthesia ere pu:lished after the start of this audit. 'ur data are largel6 compliant ith standard

first set :6 the


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provide regional anaesthesia for @J of omen having categor6 4 Caesarean section, 5J have their

operation ith a regional and are spared the riss of general anaesthesia.


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An inade=uate pre7operative :loc as associated ith an increased ris of intra7operative failure. -n

man6 cases here surger6 as started in the presence of an inade=uate :loc, the reasons for this

ere unclear. oever, $0J of these cases ere started :ecause of urgenc6 or ith a rising :loc.

+loc eFtent as assessed using cold sensation. ?he use of cold is more specific :ut less sensitive tha

touch &4(. ?his is :orne out :6 the finding that !$J of general anaesthetic conversions occurred

during the operation, mostl6 in the presence of an ade=uate pre7operative :loc. Although the use of

touch to assess anaesthetic :loc for Caesarean section has :een strongl6 recommended &4(, there ia lac of data shoing that it can reduce the rate of intra7operative pain or general anaesthetic

conversion, or indeed overall general anaesthetic conversion &4D(.

?he ma>orit6 of spinals ere inserted in the right lateral position. ?he sitting position as associated

ith a higher intra7operative failure rate using univariate anal6sis "5.4J versus right lateral $.EJ#.

Su:dividing omen ho ere sitting for spinal insertion into groups :ased on the indication for sittin

as an attempt to separate clinicall6 straightforard cases from those ith o:esit6 or predicted

anatomical difficult6, hich might have :een confounding factors. -ntra7operative failure occurred in

@.!J of cases here the spinal as inserted sitting :ecause of the anaesthetist/s preference. 'ther

audit data has also suggested an increased chance of intra7operative pain if the spinal is inserted

sitting &40(. oever, using logistic regression anal6sis, insertion position as not found to :e a

significant factor affecting intra7operative failure.

-t has :een suggested that the use of spinal diamorphine does not affect the =ualit6 of :loc assessed

ith touch sensation &48(, :ut reduces pain during surger6 &4E(. ?his audit found an increase in the

chance of pre7operative failure to achieve a successful :loc to cold if a spinal opioid as not used,

:ut no difference in intra7operative failure. -ntra7operative pain as found in !.5J of spinals ith anopioid and 44.4J ithout, :ut as L 4J of spinals did not have a spinal opioid, the poer to detect a

real difference is lacing.

An association :eteen nulliparit6 and increased pre7operative failure for spinals is uneFplained. 'n

the other hand, preterm deliver6 has :een identified as a factor in failure to esta:lish spinal :loc

&$0(.

Several randomised studies comparing epidural top7up solutions have failed to find a clincall6

important difference :eteen different local anaesthetics or ith the addition of fentan6l &44, 4$,

$4(. ?hese studies assessed time of onset of surgical :loc :ut ere too small to detect differences in

failure rate. ?he use of different solutions in this audit as spread such as to allo reasona:le

num:ers in each group for anal6sis ":upivacaine 58J, lidocaine $!J, lidocaine7:upivacaine miF 4JN

adrenaline @JN :icar:onate $JN opioid 8!J#. Apart from adrenaline, these factors did not feature in

the univariate or logistic regression anal6ses. Adrenaline, hoever, approFimatel6 halved the ris :ot

of pre7operative and intra7operative failure. e have considered an epidural top7up volume of $0%$@

ml to :e standard/ as anaesthetists usuall6 dra up $0 ml of local anaesthetic and other ad>uncts

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ma6 then :e included. Smaller volumes than $0 ml are associated ith less ris of pre7operative

failure possi:l6 indicating ade=uac6 of the eFisting analgesic :loc, hereas volumes of $5 ml or

a:ove are associated ith diminishing returns in terms of success.

?he most common indication for primar6 general anaesthesia as Caesarean section urgenc6

associated ith fetal distress, hether considering all cases, categor6 4 cases, or cases here

epidural analgesia as used during la:our :ut not topped up. Conversion of inade=uate regionalanaesthesia to general anaesthesia accounted for !5J of all omen ho had a general anaesthetic.

?his percentage is higher as the the primar6 general anaesthetic rate falls &@(. -t is pro:a:l6

appropriate that 88J of general anaesthetic conversions in categor6 4 cases ere pre7operative.

ains et al. estimated that in the late 4E80s, the ris of death from o:stetric general anaesthesia

as 4D times that of regional anaesthesia &$$(. Shi:li and


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5 ;ucas Q, Ientis SM, Kinsella SM, et al. 2rgenc6 of caesarean section3 a ne classification. ournal

of the


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4


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igure. Qo Caption availa:le.
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A Prospective Audit of Regional Anaesthesia Failure in 5080 Caesarean Sections