Scandinavian clinical practice guidelines on general anaesthesia for emergency situations

29 Pages·2010·0.34 MB·English

ActaAnaesthesiolScand2010;54: 922–950 r2010TheAuthors
PrintedinSingapore.Allrightsreserved Journalcompilationr2010TheActaAnaesthesiologicaScandinavicaFoundation
ACTAANAESTHESIOLOGICASCANDINAVICA
doi:10.1111/j.1399-6576.2010.02277.x
Review Article
Scandinavian clinical practice guidelines on general
anaesthesia for emergency situations
A. G. JENSEN1, T. CALLESEN2, J. S. HAGEMO3, K. HREINSSON4, V. LUND5 and J. NORDMARK6
1DepartmentofanaesthesiologyandIntensiveCare,OdenseUniversityHospital,Odense,Denmark,2DepartmentofAnaesthesiology2041,
Rigshospitalet,Copenhagen,Denmark,3DepartmentofResearchandDevelopment,NorwegianAirAmbulanceFoundation,Drøbak,Norway,
4DepartmentofAnaesthesiaandIntensiveCareMedicine,Landspitali,NationalUniversityHospital,Reykjavik,Iceland,5IntensiveCareUnit,
SatakuntaCentralHospital,Pori,Finlandand6DepartmentofAnaesthesiologyandIntensiveCare,KarolinskaUniversityHospital,Stockholm,
Sweden
Emergency patients need special considerations and the obese patients should be performed in the head-up
numberandseverityofcomplicationsfromgeneralanaes- position. The use of cricoid pressure is not considered
thesia can be higher than during scheduled procedures. mandatory, but can be used on individual judgement.
Guidelines are therefore needed. The Clinical Practice The hypnotic drug has a minor influence on intubation
CommitteeoftheScandinavianSocietyofAnaesthesiology conditions, and should be chosen on other grounds.
and Intensive Care Medicine appointed a working Ketamine should be considered in haemodynamically
group to develop guidelines based on literature searches compromised patients. Opioids may be used to reduce
to assess evidence, and a consensus meeting was held. the stress response following intubation. For optimal
Consensus opinion was used in the many topics where intubation conditions, succinylcholine 1–1.5mg/kg is
high-grade evidence was unavailable. The recommenda- preferred. Outside the operation room, rapid sequence
tions include the following: anaesthesia for emergency intubation is also considered the safest method. For
patients should be given by, or under very close super- all patients, precautions to avoid aspiration and other
vision by, experienced anaesthesiologists. Problems complications must also be considered at the end of
with the airway and the circulation must be anticipated. anaesthesia.
The risk of aspiration must be judged for each patient.
Pre-operative gastric emptying is rarely indicated. For
Acceptedforpublication18June2010
pre-oxygenation, either tidal volume breathing for
3min or eight deep breaths over 60s and oxygen r2010TheAuthors
flow 10l/min should be used. Pre-oxygenation in the Journalcompilationr2010TheActaAnaesthesiologicaScandinavicaFoundation
THESE guidelines are on the topic of general handling these patients, and thereby to provide
anaesthesia for emergency situations. Emer- anaesthesiologists in the Nordic countries with a
gency patients are a major challenge for an anaes- mutual understanding and a common way to
thesiologist. They need special considerations and anaesthetizethesepatients.Hopefully,theseguide-
the number of complications and adverse events, lines may assist anaesthesiologists in the care for
including human errors, from general anaesthesia patients,sothatpatientscanbetreatedwithsimilar
may be higher than during scheduled procedures. standards and equal high quality in our different
Among the complications and events are haemo- countries and hospitals.
dynamic alterations and airway-related conse- Theworkinggroupdefinesanaesthesiaforemer-
quences. Guidelines can be used to reduce these gency situations as anaesthesia that is not planned
complications and events and to make treatment or not for elective patients. Regional anaesthesia
and handling uniform and evidence based. may be a good solution in many emergency pa-
The work on these guidelines was initiated, and tients, but finding evidence to assist the anaesthe-
the working group was appointed by the Clinical siologist in choosing between regional and general
Practice Committee (CPC) of the Scandinavian anaesthesia and describing regional anaesthesia
Society of Anaesthesiology and Intensive Care has not been the topic for this working group.
Medicine (SSAI). The aim was to find the evidence However, we all must remember to evaluate the
and latest scientific information for our way of airway before the decision is made to administer
922
Guidelines on general anaesthesia for emergency situations
generalanaesthesia.Theworkinggrouphasfocused Table1
on the anaesthesia technique when it has been
Summaryofrecommendations.
decided, that the patient should be given general
Pre-operatively
anaesthesia. This implies that the group has not
Anaesthesiaforemergencypatientsshouldbegivenby,or
discussedpre-operativeoptimization,orindications underveryclosesupervisionby,anexperienced
and contraindications for the individual patient. anaesthesiologist.Haemodynamicandairway-related
complicationsshouldbeanticipated.Alternativeplansand
Emergency patients are presented to anaesthesiolo-
adequateequipmentfordealingwiththesecomplicationsmust
gists both outside and inside the operation rooms beready.Inpatientswithanincreasedriskofaspirationof
(OR), and therefore care of patients outside OR has stomachcontentstothelungs,precautionstoavoid
regurgitationmustbetaken.Unlessthepatienthasanincreased
also been considered in the guidelines. The guide-
riskofaspiration,patientsscheduledforemergencysurgerycan
lines cover only the management of general anaes- beconsideredfastingandcanbetreatedaccordingtostandards
thesia in adult emergency patients. A short version forscheduledpatients,ifmorethan2hhaveelapsedsincethe
lastintakeofclearfluidsandmorethan6hhaveelapsedsince
of the guidelines is presented in Table 1.
thelastintakeofameal.Inpatientsatahighriskof
A grading system for recommendations and regurgitation,eitheranH -blockeroraprotonpumpinhibitorcan
2
level of evidence was recommended by the CPC. beusedtoreducetheacidityandvolumeintheventricleor
sodiumcitratecanbeusedtoreduceacidity.Pre-operative
Hence, decisions on the level of evidence and
gastricemptyingwithanorogastricoranasogastrictubeis
grading of recommendations have been made ac-
rarelyindicated.
cording to Bell et al.1 Decisions about both level of
Pre-oxygenationandcricoidpressure
evidence and grading of recommendations can be Pre-oxygenationisinitiatedbyexplainingtheproceduretothe
foundinthe individualchapters. Inthetext,Grad- patient.Avoidaleakbetweenthepatient’sfaceandtheoxygen
mask.Eithertidalvolumebreathingfor3minoreightdeep
ingofevidencefromItoVisaddedinbrackets,[],
breathsover60swithanoxygenflowofatleast10l/minshould
and Grading of recommendations from A to E can beused.Non-invasivepositivepressureventilationorthe
be found in tables and text. applicationofpositiveend-expiratorypressurecanbe
consideredinmorbidlyobeseorcriticallyillhypoxicpatients.
Pre-oxygenationinobesepatientsshouldbeperformedinthe
head-upposition;otherwise,thereisnoadvantageofone
placementovertheother.Theuseofcricoidpressureisnot
Methods
consideredmandatory,butcanbeusedonindividual
judgement.Ifused,thecricoidpressuremustbeusedcorrectly,
Literature references were found after a search in
andthepressureshouldbereleasedifventilationor
Pub Med, inclusive of Mesh, and the Cochrane laryngoscopyandintubationaredifficult.Cricoidpressure
Library. Further, cross references from relevant shouldalsobereleasedbeforeinsertingtheLaryngealMask
Airwayshouldinitialattemptsattrachealintubationprove
studies have been used. The Search words are
unsuccessful.
specified in Appendix 1. The time frame for the
Drugs
search has been from August 1961 to May 2009. Thehypnoticdrughasaminorinfluenceonintubation
Grading of evidence and grading of recommenda- conditions,andshouldbechosenonothergrounds.
Thiopentoneseemstobeabetterchoicethanpropofoltoavoid
tions were performed according to a system first
hypotensionfollowinginduction.Ontheotherhand,propofolisa
used by Bell et al.1 Table 2. According to this
betterchoicethanthiopentonetoavoidacardiovascularstress
system, evidence is graded from A to E, where responseinpatientswithischaemiccardiacdisease.Ketamine
recommendationgradeAindicatesarecommenda- shouldbeconsideredforhypovolaemicpatients(hypovolaemic
shockorpre-shock)orforcardiovascularunstablepatients
tion based on the best evidence. An immense
whenthereisnotimeorpossibilityofpre-operativeoptimization.
problem throughout this work has been the lack Anopioidcanbeusedtoreducethestressresponsefollowing
of evidence grades I and II in many areas. Accord- intubation.Aneuromuscularblockingagentisusedtooptimize
intubationconditions.Foroptimalintubationconditions,
ingly, the working group has graded few recom-
succinylcholine1–1.5mg/kgispreferredoverother
mendationsasA.Asthescientificevidenceisweak neuromuscularblockingdrugs.Wherecontraindicationsto
in many areas, we have consented to grade many succinylcholineexist,rocuronium0.9–1.2mg/kgisanadequate
alternative.
recommendations as D or E.
The individual chapters were written in drafts, Anaesthesiaoutsidetheoperationroom
Rapidsequenceintubationisconsideredthesafestmethod.
and after initial discussions via mail, a consensus
Awakeintubationcanbeperformedinselectedcases.For
meeting was held. Evidence was assessed and inductionofanaesthesia,allavailableinductionagentscanbe
grading of recommendations was decided. Con- used.
sensusopinionwasusedinthemanytopicswhere Endofanaesthesia
high-grade evidence was unavailable. The specific Takeprecautionsalsoattheendofanaesthesiatoavoid
haemodynamicandairway-relatedcomplicationsaswellas
grading of evidence and grading of recommenda-
regurgitation.
tioncanbefoundintheindividualchapters,where
923
A. G. Jensen et al.
Table2 Background
Gradingofrecommendationsandevidence. Themainaimsofgeneralanaesthesiainemergency
patientsaretoputthepatienttosleepassafelyand
Gradingofrecommendations
quickly as possible, and to secure the airway
A SupportedbyatleasttwolevelIinvestigations
B SupportedbyonelevelIinvestigation against the risk of aspiration of gastric contents.
C SupportedbylevelIIinvestigationsonly The anaesthesia technique for inducing sleep and
D SupportedbyatleastonelevelIIIinvestigation
relaxation is known as RSI. The technique is some-
E SupportedbylevelIVorVevidence
Gradingofevidence timesreferredtoasCrashInduction,firstnamedas
I Large,randomizedtrialswithclear-cutresults;lowriskofa such by Woodbridge.2 With this technique, a hyp-
false-positive(alpha)errororafalse-negative(beta)error
noticshouldbeabletoinducelossofconsciousness
II Small,randomizedtrialswithuncertainresults;moderate-
to-highriskoffalse-positive(alpha)and/orafalse-negative within a very short time, the administered opioid
(beta)error should be able to prevent or treat the haemody-
III Nonrandomized,contemporaneouscontrols
namic and other autonomic responses to tracheal
IV Nonrandomized,historiccontrolsandexpertopinion
V Caseseries,uncontrolledstudiesandexpertopinion intubation and a muscle relaxant is administered
simultaneously with the hypnotic to reduce the
ThetablehasbeenadaptedfromBelletal.1
time between sleep and intubation. General anaes-
thesia in emergency patients can be fraught with
gradingofevidencefromItoVisaddedinthetext
complications related to haemodynamic complica-
part in brackets, [ ], and grading of recommenda-
tions such as alterations in heart rate and blood
tion is presented in tabular form.
pressure, new-onset cardiac dysrhythmias3 and, in
Adraft with recommendationswas presented at
the worst-case scenario, cardiac arrest.4 Further,
the 30th Congress of SSAI, June 2009. Comments
complications can be anticipated related to airway
from this presentation were incorporated into the
management, complications such as hypoxaemia,
next draft, and this draft was presented for com-
failedintubation,multipleintubationattempts,and
ments and critique on the SSAI website* from
aspiration of gastric contents.5,6 Alternative plans
August until November 2009. Each member of
must be ready in order to handle the patient if
the SSAI was sent an email to notify them of the
haemodynamic or airway-related complications
possibilityofreadingandcommentingonthedraft.
should occur. These alternative methods include
Comments from SSAI members have been incor-
awakening the patient with reestablishment of
poratedandthepresentmanuscriptandtheguide-
spontaneous ventilation. When the patient is
lineshavebeenapprovedbyCPCinFebruary2010.
awake and the situation is stabilized, regional
anaesthesia or awake fibreoptic-assisted tracheal
intubation should be considered. These guidelines
will not further discuss intubation problems and
Initial considerations difficult airway algorithms as guidelines on these
topics can be found elsewhere.7,8 Graded recom-
Recommendation
mendations for initial considerations are summar-
Anaesthesia for emergency patients should be
ized in Table 3.
administered by, or under close supervision by,
We have not been able to find descriptions of
experienced anaesthesiologists. An alternative
currentpractice in Scandinavia. Studies performed
plan should always be ready for use if failed inEngland9andWales10haveshownthatthereisa
intubationorhaemodynamiccomplicationsshould
wide variation in techniques and skills and that
occur. The ASA difficult airway algorithm should there is room for improvement.9 An accepted
be known and followed, and the alternative plan
practice regarding drug administration during
should include the option to awaken the patient
RSI is to administer the pre-determined doses of
andbereadytocontinuewithawakeintubationor
thedifferentdrugsrapidly,withoutwaitingforthe
regional anaesthesia. Even though the technique is
effect of the single drug. An alternative method
known as rapid sequence induction or rapid se-
would be to titrate the doses of drugs over a more
quenceintubation(RSI),themusclerelaxantcanbe
prolonged time period. The rationale for rapidly
administered after the effect of the hypnotic drug
administering pre-determined doses is that the
has been observed.
majority of hypnotics and opioids reduce both the
upper and the lower oesophageal sphincter (LES)
*http://www.ssai.info tone11,12andthusincreasetheriskofregurgitation.
924
Guidelines on general anaesthesia for emergency situations
Table3 The three major factors considered to be able to
reduce the incidence of aspiration are experience,
Recommendationsforinitialconsiderations.
assistance by experienced anaesthesiologists and
Recommendation Grading
close supervision of inexperienced anaesthesiolo-
Anaesthesiaforemergencypatientsshouldbe D gists16 [III]. Studies have shown that residents lack
givenbyanexperiencedanaesthesiologist
Theinexperiencedanaesthesiologistshouldbe D knowledge and practical skills in airway manage-
assistedandcloselysupervisedbyanexperienced ment17 [III]. Further, supervision of residents by
anaesthesiologist
attending anaesthesiologists can reduce the com-
Drugscanbeadministeredinrapidsequenceor E
theneuromusculardrugcanbeadministeredafter plications of emergency tracheal intubation18 [III].
thepatienthasfallenasleep Itisnotpossibletodefineexactlywhenatraineeis
Bepreparedtouseanalternativeplanfor E
adequately experienced to handle an emergency
intubationiffailedintubationoccurs
patient on her/his own. Complications to anaes-
Regionalanaesthesiaorawaketrachealintubation E
shouldbeconsideredinpatientswithdifficult thesia for elective cases are known to be reduced
airways.Inthesecases,theASAdifficultairway after3–6monthsoftraining.Constructing learning
algorithmshouldbeused
curves for residents have shown that a trainee
Recommendationgradesarebasedonthegradingsystemused needs 60–80 cases of successfully performed intu-
byBelletal.1 bationstobeabletoperformtheprocedurequickly
andsafely19,20[III].Hence,thesenumbersmightbe
usedwhendecidingwhetherornotatraineecanbe
Thegoalofmaximalinjectionofspeedistorapidly trusted with the responsibility of administering
achieve a state of anaesthesia, which allows fast anaesthesia to the emergency patient.
tracheal intubation and in this way reduces the Anaesthesia for emergency situations is challen-
time during which patients are at risk of gastric ging, and patient safety depends on the skills,
aspiration. If haemodynamic or other complica- vigilance and judgement of individuals working
tions of rapid bolus injections are severe, this as a team.21 Studies have shown that anaesthesia
adverseoutcomemightreducethepotentialbenefit care improves with training, and some advocate
of the rapid tracheal intubation. experience gained in a simulated environment
It has not been possible to find data comparing usingahumansimulator.21,22CrewResourceMan-
the risk of complications associated with a rapid agement with training in the components charac-
injectionwiththeriskofaspirationassociatedwith terizingeffectiveteamshasbeenattempted,butthe
a prolonged interval before tracheal intubation. scientific evidence for improvement in care for
Further, evidence could not be found supporting the emergency patient is still scarce. Hopefully, in
the technique of restricting rapid drug administra- thefuture,studieswillbeperformedonemergency
tion to patients and circumstances with a high risk patients and teams, determining the effect of
of aspiration and a low risk of complications effective leadership, mutual performance monitor-
associated with this. It was not possible to find ing, backup behaviour, adaptability and team
data to support the statement that injection of a orientation.22
hypnotic should be followed by a neuromuscular
blocking agent (NMBA) only after the resulting
effectofthehypnotichasbeenseen(thepatienthas Fasting conditions and identification
fallen asleep). and treatment of patients at a high risk
The reported incidence of aspiration of gastric
of aspiration of gastric contents
contentstothelungsseemstobelow.Inemergency
anaesthesia, the incidence is higher than that in Recommendations
planned anaesthesia.13–16 In emergency anaesthe- Emergency and elective surgical procedures are
sia, the incidence is quoted to be one case in every treated in the same way with respect to fasting
634 to 809 patients.13,15 In the planned cases, the conditions. Exceptions and risk factors are identi-
incidenceismuchlower,becausetheincidenceina cal, i.e. gastrointestinal obstruction or delayed gas-
mixture of cases is one out of 2131 to 3457 pa- tric emptying.
tients.13,15 The incidence increases in the presence Patients scheduled for emergency surgery are
of risk factors or complications such as ileus, considered fasting if more than 2h has elapsed
obstetric emergencies, light planes of anaesthesia, since the last intake of clear fluids and more than
morbid obesity and difficult intubation.13,15,16 6hhaveelapsedsincethelastmeal(inclusiveofall
925
A. G. Jensen et al.
Table4 compared with 2–4h of fasting. The general re-
commendation for elective surgery is 2h for clear
Recommendationsforthedurationoffastingconditionsandfor
thetreatmentofpatientsatahighriskofaspiration. fluids, and 6h for all other kinds of nutrition23–28
[IV–V].
Recommendation Grading
Userapidsequenceinductioniftheemergency E
patientisnonfastingorhasanincreasedriskof
aspirationorifthereisanydoubtaboutthis Increased risk of pulmonary aspiration of
Patientsconsideredtohaveahighriskof
gastriccontentsordelayedgastricemptying
aspiration:ileus,subileus,bowelobstruction,
pregnancy,hiatalhernia,reflux,nauseaorvomiting
pre-operatively Patients with a high risk of pulmonary aspiration:
Patientsconsideredtohaveapossibleriskof E
aspiration:morbidobesity,diabetes,acuteopioid (cid:2) patients with subileus, ileus or bowel obstruc-
treatment tion are considered non-fasting, irrespective of
Unlessthepatienthasanincreasedriskof E
the time elapsed since the last meal or drink,
aspiration,patientsscheduledforemergency
and insertion of a naso-gastric/-duodenal tube
surgerycanbeconsideredfastingandcanbe
anaesthetizedaselectivepatients,ifmorethan2h at the ward before anaesthesia is necessary;
haveelapsedsincethelastintakeofclearfluids (cid:2) pregnant women of more than 20 weeks of
andmorethan6hhaveelapsedsincethelast
gestation, including the first 24h post partum;
intakeofameal.
Pre-operativegastricemptyingwithanorogastric E (cid:2) patients with hiatal hernia or gastro-oesopha-
oranasogastrictubeisrarelyindicated.If geal reflux;
necessary,usealarge,double-lumentube
(cid:2) patients with pre-operative nausea/vomiting,
Pre-operativegastricemptyingwithorogastricor E
nasogastrictubeismandatoryduringpre-operative e.g. in connection with newly started opioid
treatmentofpatientswithileus,subileusorbowel pain treatment.
obstruction.Treatmentshouldbestartedatthe
wardandcontinuedduringanaesthesiainduction
Patients with a possible increased risk:
Prokineticdrugsarenotrecommendedtoreduce E
theriskofpulmonaryaspiration (cid:2) morbidly obese patients (BMI435);
Antiemeticdrugsarenotrecommendedtoreduce E
(cid:2) diabetic patients (considering the risk of poly-
theriskofpulmonaryaspiration
UsingeitheraH -blockeroraprotonpumpinhibitor B neuropathy and gastro paresis);
2
isrecommendedinhigh-riskpatients,asthese (cid:2) patients who have received opioids to alleviate
drugsreducegastricacidityandvolume
acute pain without developing nausea or
Sodiumcitratecanbeusedtoreduceacidityinthe B
gastricfluids vomiting.
Recommendationgradesarebasedonthegradingsystemused These patients should be individually assessed,
byBelletal.1
considering the type and duration of surgery,
severity and duration, degree of obesity and their
general health condition, including airway assess-
types of dairy products), unless the patient suffers ment. Assessment including specific questioning
from intestinal paralysis/paresis, bowel obstruc- about heartburn, nausea, vomiting and reflux
tionorisconsiderednon-fastingafteranindividual should be documented in the patient file.
assessment. Patients considered non-fasting, for
instance due to pain, critical illness or medical
conditions,aregivenRSIonaliberalbasis.Recom- Gastric emptying by an orogastric or a
mendations with grading of recommendations can
nasogastric tube
be found in Table 4.
Recommendation
Pre-operative gastric emptying by an orogastric
Background tube is not recommended for routine use before
No randomized studies are available to determine emergency surgery and it is contraindicated in
the optimal period of fasting regarding emergency conditions with a risk of organ rupture, fractures
surgery with respect to patient comfort or morbid- of the cervical spine and increased intracranial or
ity/mortality. Studies on elective surgery show an intraocularpressure.Ifindicated,alarge-boredou-
inverse relationship between the duration of fast- ble-lumen tube should be preferred.
ing and patient satisfaction, and that fasting more Anasogastrictubeshouldbeleftinplaceduring
than 6h does not improve gastric emptying when induction of anaesthesia, and suction should be
926
Guidelines on general anaesthesia for emergency situations
applied to the tube to remove as much gastric Medical pre-treatment to reduce acid
content as possible before induction. A correctly secretion
applied cricoid pressure can be used to possibly
Recommendation
reduce the risk of aspiration of gastric contents.
Routine use of either a histamine-2-blocking agent
(ranitidine 50mg) or a proton pump inhibitor
(omeprazole 40mg) is recommended for high-risk
Background
patients. It should preferably be administered in-
Gastric emptying by an orogastric tube is rarely
travenously 6–12h before surgery and repeated at
indicated15[IV],anddoesnotensuregastricempti-
least30minbeforeanaesthesiainduction toreduce
ness29 [III]. A large-bore double lumen with
boththeacidityandthevolumeofgastriccontents.
side holes is more efficient than a small-bore
A single-dose regimen of ranitidine reduces the
single-lumen tube29 [III] for emptying of gastric
acidity but not the volume of gastric contents.
fluids. There is no evidence to support that solid
Sodium citrate 30ml 0.3M by mouth could be
matters can be removed by an orogastric
added before induction to neutralize acidity.
tube. Pulmonary aspiration of gastric contents
may occur despite the use of an orogastric tube
for emptying 16 [V]. Background
In healthy volunteers, gastric reflux is not in- Nostudiesareavailableontheuseofacidsecretion
creased by short time placement of a thick gastric inhibitors and the risk of pulmonary aspiration of
tube up to 12F29–31 [III, II and V]. Patients under- gastric contents during anaesthesia. Cimeti-
going abdominal surgery with a perioperatively din37,38[I and III] and ranitidine reduce gastric
placed nasogastric tube have significant reflux acidity as well as the volume of contents39 [II],
of gastric contents32[II], with an increased inci- with the longest duration of effect by ranitidine.
dence of fever, atelectases and pneumonia post- Enhanced effect either by a repeated administra-
operatively33[I]; the duration of the insufficiency tion of ranitidine or in combination with sodium
of the oesophageal sphincter is not known. citratehasbeendiscussed.Theuseofprotonpump
Anasogastrictubedoesnotdiminishthesupposed inhibitors has been described for emergency cae-
protective effect of cricoid pressure during sarean section, and some describe a single dose as
intubation 34 [V]. being inadequate40 [II], whereas it is effective if
given in combination with sodium citrate and
metoclopramid41 [II]. ASA does not recommend
Medical pre-treatment to increase gastric routine use and it is not a safeguard against
aspiration during anaesthesia16 [V].
emptying by increasing gastro-intestinal
motility
Recommendation Medical pre-treatment with antacids
The use of pro-kinetic drugs is not recommended
Recommendation
to reduce regurgitation and pulmonary aspiration.
Routine use is recommended only to high-risk
The drug can be used to reduce gastric contents.
patients,includingemergencyobstetricprocedures
under general anaesthesia.
Background
Metoclopramid given 90min pre-operatively re- Background
duces the volume of gastric contents35 [I]. The No studies are available to demonstrate reduced
effect outbalances the reduction in gastric empty- morbidity or frequency of pulmonary aspiration
ing by morphine36 [II]. Thereis no effect on gastric during anaesthesia after oral intake of antacids.
acidity by Metoclopramid. The relation between Despite this, antacids have been generally recom-
prokinetic drugs and aspiration has not been stu- mended since 196642 [V] and since 1993 in Den-
died. Routine use pre-operatively is not recom- mark specifically before emergency obstetric
mended by ASA28[V]. Aspiration of gastric surgery43 [V]. Thirty millilitre sodium citrate
contents during anaesthesia has been described in 0.3M increases the pH in the stomach to almost
patients pre-treated with prokinetic drugs.16 neutral values after a few minutes, but its effect
927
A. G. Jensen et al.
wearsoffifgivenmorethan1hbeforeanaesthesia. Table5
A combination of ranitidine and sodium citrate
Recommendationsonpre-oxygenation.
leads to a speedy response44,45 lasting up to 14h
Recommendation Grading
[III and II]. The intake of sodium citrate increases
Explaintheproceduretothepatient E
thegastricvolumecorrespondingly,butwithoutno
Avoidaleakbetweenthemaskandthepatient’s E
other known side effects46 [III]. ASA does not face
recommend routine use, and it is not a safeguard Tidalvolumebreathingfor3minoreightdeep A
against aspiration during anaesthesia16 [V]. breathsover60s,bothwithanoxygenflowofat
least10l/min,areequallyeffectiveforoxygenation,
andoneofthesetechniquesshouldbeused
Pre-oxygenationinobesepatientsshouldbe A
Medical pre-treatment with antiemetics
performedinthehead-upposition
Useofnon-invasivepositivepressureventilation C
Recommendation canberecommendedinmorbidlyobeseorin
The use of antiemetics is not recommended to criticallyillhypoxicpatients
Useofpositiveend-expiratorypressurecanbe D
reduce the risk of aspiration.
recommendedinobesepatients
Recommendationgradesarebasedonthegradingsystemused
Background byBelletal.1
Antiemetics reduce post-operative nausea and vo-
miting. No studies are available to describe the
effect on gastric content acidity or volume, and no mask and the patient’s face must be used. In obese
studies are available on the risk of post-operative patients, pre-oxygenation is more effective and
aspiration and the use of antiemetics. It is not should be carried out with the patient in the half-
recommended by ASA28 [V]. sitting or the head-up position. Further, non-inva-
sive positive pressure ventilation can be used in
obese patients and in hypoxic or critically ill pa-
Medical pre-treatment with anticholinergic
tients. Graded recommendations for pre-oxygena-
agents
tion can be found in Table 5.
Recommendation
The use of anti cholinergic drugs is not recom-
mended to reduce aspiration of gastric contents. Background
Theprimaryreasonstomaximallypre-oxygenatea
patient aretoprovidethepatient withamaximum
Background
amount of time to tolerate apnoea and to provide
No studies are available on the effect of anti
theanaesthesiologistwiththemaximumamountof
cholinergic agents and the risk of aspiration. Gly-
time to solve a ‘cannot ventilate, cannot intubate’
copyrrolate reduces tone in the LES and thus
situation. Different end points have been used in
increases the theoretical risk of reflux 47 [V]. It
studies assessing the effectiveness of various pre-
might, however, reduce the acidity and volume of
oxygenation techniques. These are as follows: the
gastric contents, but less predictably than cimeti-
highest arterial oxygen tension achieved, the high-
dine48–51 [II and III]. The use of Glycopyrrolate is
est fraction of end tidal oxygen concentration
not recommended by ASA28 [V].
achieved, the speed of achieving these highest
fractions, pulmonary nitrogen washout time and
Pre-oxygenation thetimetodesaturationtoapre-definedvalue.The
latter is also named by some as the safe apnoea
Recommendations time. There is not always a correlation among the
Hypoxaemia is a serious complication in emer- results obtained with the different end points and
gency patients administered general anaesthesia. presumably the most meaningful outcome is the
Every available method to avoid this complication safe apnoea time. Hence, articles measuring safe
must be used. If the patient is awake and coopera- apnoea time have been weighted higher.
tive, the procedure must be explained before pre- Before discussing the different methods of pre-
oxygenation is begun. To make pre-oxygenation oxygenation, it is necessary to mention that avoid-
effective, an oxygen flow of at least 10l/min for ing a leak between the patient’s face and the
3min and without leakage between the oxygen mask may increase oxygenation. Further, it is not
928
Guidelines on general anaesthesia for emergency situations
possibletoholdthemaskclosetothepatient’sface tion in a 451degree head-up position.64 In contrast,
before the method and the rationale for its use has it was found that non-pregnant women had a
been explained to the patient. These important longer safe apnoea time after pre-oxygenation in
messages are, however, supported only by numer- the head-up position compared with pre-oxygena-
ous citations in text books and by two non-rando- tion in the supine position.64
mized studies in volunteers52, 53 [III]. Both these
studies used end tidal oxygen fraction as the
outcome. Effect of maximal exhalation
Three studies, two from the same Centre65,66 [III],
have focused on the effect of maximal exhalation
Tidal volume breathing
before pre-oxygenation. In a small study compris-
Three randomized-controlled trials have demon- ing 10 healthy patients, it was found that the
strated that tidal volume breathing for 3min pro- single vital capacity breath technique following
vides a longer safe apnoea time than 4 deep forced exhalation could provide adequate pre-
breaths54–56 [I]. One study has demonstrated a oxygenation within 30s.65 The effect parameter
comparable safe apnoea time using 3min of tidal was an arterial oxygen partial pressure of 295(cid:3)
volume breathing and 8 deep breaths over a time 65mmHg achieved with the single vital capacity
periodof60s57[I].Bothmethodsweresuperiorto4 breath technique.65 In the other study, using
deepbreathsover30s.57Similarresultswerefound healthyvolunteers,maximalexhalationbeforetidal
by measuring the end tidal oxygen fraction in volume breathing produced a significantly faster
pregnant women58 [I]. Three studies have focused increase in the end-expiratory oxygen concentra-
on extension of the pre-oxygenation period. In a tion than oxygenation with tidal volume breathing
non-randomized study using arterial oxygen sa- alone.66 However, the conclusion from the most
turation as an effect parameter, there was no effect recent studyin 15healthyvolunteers wasthat pre-
of increasing the pre-oxygenation period from 4 to oxygenation with maximal exhalation before tidal
either 6 or 8min and such an extension was even volume breathing for 5min slightly steepens the
found to jeopardize oxygenation efforts in some initial rise in ETO2 during the first minute, but
patients59 [III]. In contrast, studying parturients, it confers no real benefit if maximal pre-oxygenation
was found that a higher arterial oxygen partial is the goal67 [III]. In this study, maximal exhalation
pressure was produced with 5min of tidal volume before deep breathing for 2min had no added
breathing, compared with 4, 6 or 8 rapid vital value in enhancing pre-oxygenation.67
capacity breaths60 [III]. If the technique with deep
breathing is used, it was demonstrated to be
Pre-oxygenation combined with ventilation
necessary to extend the time period to 11/2 or
2min, and to use an oxygen flow of 10l/min to or with positive end-expiratory pressure
achieve a similar end tidal oxygen concentration (PEEP)
as that found when using normal breathing for
Pre-oxygenation combined with some kind of ven-
3–5min61 [III].
tilation before intubation has been studied in two
randomized studies from the same centre. Non-
invasive ventilation was followed by a higher
Effect of position
oxygen saturation than 3min of standard pre-
Theeffectsofpositionduringpre-oxygenationhave oxygenation in critically ill, hypoxic patients 68 [I].
beenstudiedintworandomizedstudies62,63[I]and For the control group comprising 26 patients, pre-
in one non-randomized clinical study64 [III]. All oxygenationwasperformedusinganon-rebreather
three studies measured time to desaturation to a bag-valvemaskdrivenby15l/minoxygen.Forthe
predetermined level, i.e. the safe apnoea time. It NIV group with 27 patients, pressure support
was concluded that pre-oxygenation using the ventilation was delivered by a ventilator through
head-up position in obese patients (251) prolonged a face mask with an FiO of 100% and a PEEP of
2
the safe apnoea time in comparison with pre-oxy- 5cmH O. The pressure was adjusted to obtain an
2
genation in the supine position.62, 63 In the non- expired tidal volume of 7–10ml/kg. The positive
randomized study from 1992, it was found that effect on oxygen saturation was also demonstrable
pregnant women do not benefit from pre-oxygena- 5min after intubation, and there were no differ-
929
A. G. Jensen et al.
ences, either in regurgitations or in new infiltrates occasion.76Therecommendationreadingthesetwo
onpost-procedurechestX-ray.68Inmorbidlyobese studies is that it may be acceptable to ventilate the
patients,bothahigherandafasterriseinendtidal acute patient by a facemask using pressures below
oxygen saturation were found using non-invasive 20cmH O or, if using cricoid pressure, the insuf-
2
positive pressure ventilation in comparison with a flation pressure could be higher.
standard pre-oxygenation technique69 [II]. The
authors used a positive pressure of 14cmH O in
2
the study group (pressure support with 8cmH O
2
andPEEP with 6cmH O), andfound nodifference
2 Cricoid Pressure (Sellick’s Manoeuvre)
in the side effects between the two groups.69 In a
previous study, it was demonstrated that after Recommendations
sleep induction, ventilation with 100% oxygen for Theuseofcricoidpressuretoreduceregurgitationis
1min before intubation and pre-oxygenation for not based on scientific evidence. Therefore, its use
3min were equally effective in preventing hypox- cannot be recommended on the basis of scientific
aemia during induction70 [III]. PEEP applied dur- evidence. Anaesthesiologists can use the technique
ing induction of anaesthesia may prevent on individual judgement, but the anaesthesiologist
atelectasis formation in the lungs, in both non- must be ready to release the pressure if necessary.
obese and obese patients71,72 [II]. Application of Cricoidpressurehasbeenshowntolimittheglottic
PEEPhasalsobeenshowntoincreasetheduration viewduringlaryngoscopy,anditshouldbereleased
of non-hypoxic apnoea73,74 [II]. The technique for if such problems occur. Under these circumstances,
applicationofPEEPusedinthesestudies,however, backwards-upwards-right pressure on the thyroid
cannotbe usedinemergency patients.Theauthors cartilage could improve the glottis view. Cricoid
pre-oxygenated patients using 100% oxygen admi- pressure should also be released if it becomes
nisteredviaaCPAPdevice(6–10cmH O)for5min. necessary to use a laryngeal mask airway (LMA).
2
Following induction of anaesthesia, patients in the Finally,ifcricoidpressureisused,itmustbeapplied
study groups were ventilated via a face mask for at the correct anatomical location and with the
another 5min, using PEEP (6–10cmH O), until recommendedpressureof30N.Gradedrecommen-
2
trachealintubation.71–74Studiescouldnotbefound dations fortheuse ofcricoid pressure can befound
showing the effect of CPAP during pre-oxygena- in Table 6.
tion without face mask ventilation with PEEP
before intubation.
During specialist training, anaesthesiologists are
generally taught that it is dangerous to ventilate Table6
non-fasting patients before intubation. The reason Recommendationsontheuseofcricoidpressure.
for this is that the facemask ventilation may cause
Recommendation Grading
stomach inflation and thereby increase the risk of
Theuseofcricoidpressurecannotbe E
regurgitation. Two early, non-randomized studies recommendedonthebasisofscientificevidence
have challenged this concept. Thus, facemask ven- Theuseofcricoidpressureisthereforenot E
consideredmandatorybutcanbeusedon
tilationusingpressuresbelow15cmH Ohavebeen
2 individualjudgement
demonstrated not to cause insufflation of the sto- Iffacemaskventilationbecomesnecessary,cricoid D
mach75[III].Whenapplyingaforcefulpressureon pressurecanberecommendedbecauseitmay
reducetheriskofcausinginflationofthestomach
theanteriorsurfaceoftheneck,againstthethyroid
Cricoidpressureshouldbereleasedand D
and cricoid cartilages (a technique later named
backwards-upwardsrightpressure(BURP)should
cricoid pressure), the authors could not force air beappliedinstead,ifcricoidpressurelimitsthe
into the stomach using pressures of up to glotticviewduringlaryngoscopy
Cricoidpressureshouldbereleasedbefore C
50cmH O. Furthermore, in another study, it was
2 insertingtheLaryngealMaskAirwayshouldinitial
demonstrated that in the absence of cricoid pres- attemptsattrachealintubationproveunsuccessful
sure, the minimum pressure required to cause gas Thosechoosingtousethecricoidpressureinthe D
at-riskpatientmusttakecaretoapplythecricoid
to enter the stomach of healthy patients was
pressurecorrectlyandreleasethepressureshould
20cmH2O76[III].Theseauthorsfounditimpossible ventilationorlaryngoscopyandintubationprove
to force air to enter the stomach in any of the 20 difficult
patients when cricoid pressure was applied, de-
Recommendationgradesarebasedonthegradingsystemused
spiteinsufflationpressuresexceeding60cmH Oon byBelletal.1
2
930
Guidelines on general anaesthesia for emergency situations
Background dram and Clarke,86 in a recent correspondence in
BrianSellick’sarticle ontheuseofcricoidpressure Anaesthesia, also strongly question the efficacy of
tocontrolregurgitationofstomachcontentsduring the cricoid pressure, discussing the potential bene-
inductionofanaesthesia,publishedintheLancetin fits of another technique, a 401 head-up tilt, for the
196177[V], has to be considered a landmark refer- prevention of aspiration [V]. In Sellick’s original
ence in anaesthetic practice. Although not cited in work, three out of 26 patients had a ‘reflux’ of
Sellick’s original ‘preliminary communication’ in gastric or oesophageal contents into the pharynx
the Lancet, the anatomical rationale for cricoid upon release of the cricoid pressure.77 Numerous
pressure during resuscitation had been but for- studies and case reports describing regurgitation
ward in the 1770s by Monro78 and in 1776 by and aspiration of gastric and/or oesophageal con-
John Hunter.79 tents with the cricoid pressure applied have been
Wellknowntoallanaesthesiologists,themethod published87[V],givingreasonstodoubtitseffective-
consistsofapplyingexternalpressuretothecricoid ness. The physiological response to applied cricoid
cartilage withthe intentionofoccluding the lumen pressuredeservessomemention.Applicationofthe
of the oesophagus between the cricoid cartilage cricoid pressure has been shown to lower the LES
andthecervicalvertebralcolumn(C5/C6)withthe tone and may be a contributing factor facilitating
purpose of preventing aspiration of gastric con- regurgitation andaspiration 78,87,88[V]. Metoclopra-
tents should regurgitation from the stomach occur midincreasesLESpressurebutarecentstudyfailed
duringinductionofanaesthesia.77Sellick’soriginal toshowabenefitintermsofovercomingthecricoid
description of the technique suggested that the pressure-induced lowering of the LES tone. The
head and neck should be fully extended and that authors concluded that Metoclopramid may have
the head should not be supported by a pillow aroleinincreasingbarrierpressurewhenthecricoid
[V],77,78 an anatomical position known to have the pressure is not applied or has to be released.88
potential to make tracheal intubation more diffi- Studies using advanced imaging techniques such
cult. No mention is made in Sellick’s paperof how as MRI and CTscanning have shown the oesopha-
much pressure to use, and various pressures have gus to be displaced laterally rather than occluded
been tested and used [V].8,77,78,80,81 A pressure of withthecricoidpressure89,90[III].Smithetal.,89ina
10N in the awake and 30N after induction of recentstudyofhealthyvolunteers,usingMRIscan-
anaesthesia has been recommended82 [V] and ning,foundtheoesophagustobedisplacedlaterally
seems to have been adopted universally, but pres- inoverhalfofthepatientswithoutcricoidpressure,
sures as high as 44N were recommended earlier increasing to 90.5% when cricoid pressure was
78,80,82 [V]. The application of the cricoid pressure applied. In spite of this knowledge and the doubt
has, since its introduction, been an integral part of abouttheeffectivenessofthecricoidpressure,recent
the RSI of anaesthesia for emergency surgery as textbooks on anaesthesia describe the use of the
well as in emergency airway management for the cricoid pressure, as part of the RSI of anaesthesia,
critically ill patient in the intensive care unit and withoutmentionofthe technique’seventual lack of
theemergencyroom.However,theevidenceforits efficacy91–94 [V]. Vanner,95 in a newly published
use is practically non-existent, and application of editorial, concludes that the cricoid pressure prob-
cricoid pressure might have side effects. ably is effective at preventing regurgitation at in-
duction of anaesthesia [V]. He discusses briefly
the impact of better conducted general anaesthesia
on lowering mortality from aspiration pneumonitis
Efficacy of the Cricoid Pressure
in obstetrics, making note of the cricoid pressure
TheefficacyofthecricoidpressureandeventheRSI only being one of many factors, among them
of anaesthesia to control the regurgitation of gastric pre-oxygenation, antacids and improved fasting
contents during induction of anaesthesia have been routines, making it difficult to judge the value
questioned for some time78,83–85 [V]. In a recent of each single factor. In accordance with this
review on the use of cricoid pressure in anaesthetic view,manyexperiencedcliniciansusethetechnique
practice, Priebe80 highlights the lack of scientific in their practice, claiming it to have been highly
evidence of its effectiveness. He also discusses and useful on numerous occasions. Others have taken a
reviews the potential of the cricoid pressure, both stand based on a more evidence-based approach,
correctly and incorrectly applied, to interfere with using the cricoid pressure infrequently or not
optimal airway management techniques. Gobin- at all.80
931