The Incidence of Post-Anaesthetic Myopathy with the Use of a Static

AstridB.M. Rijkenhuizenand P. van Dijk
Pferdeheilkunde14 (1998) 2 (März/April)131-1 34
The Incidenceof Post-AnaestheticMyopathywith the Use
of a Static Air Mattress
Astrid B.M. Rijkenhuizen and P. van Dijk
Department
of Generaland LargeAnimalSurgery,UtrechtUniversity
Summary
The effectof a static air mattresson the incidenceof post-anaesthetic
myopathywas studied.lt is generallyassumedthat pressureon the
muscleswill resultin an impairmentof the circulation,creatingan ischaemicconditionand cause post-anaesthetic
myopathy.An adequate
muscularperfusionis maintainedby carefulpositioningof the patientand payingattentionto the surfaceon which the horselies.As human
literature,based on the evaluationof CT-scansof subjectssupportedby varioustypes of beddingsindicate,that the use of a staticair mattress resultsin a significantreductionof compressionand may resultin lower incidenceof ulcers,this type of mattreswas selectedto be
tested for use rn horses.In 1995 1349 horseswere anaesthesized
with an averageanaesthesia
time of 98 min. Twelve(0.9%)horseshad
problemswith the recoverybecauseof myopathy.Ninelimbs(0.7%)concernedthe undersideof the horseduringanaesthesia.
keywords
post-anaesthetic
myopathy,post-anaesthetic
lameness
myositis,horse,post-anaesthetic
Häufigkeitder postnarkotischenMyopathie nach Verwendungeiner statischen Luftmatratze
Die postnarkotischeMyopathie(Muskeldysfunktion
in Verbindungmit harterSchwellungund Schmerzhaftigkeit)
entstehtdurch Druckschämie des Muskelgewebesaufgrundder Lagerungwährendder Narkose.Bei der Reperfusionwerdenfreie Radikalefrei, die zur Myopathie
führen,welche mit einer Inzidenzvon 0,75 bis 6,4% auftritt.DiesesKrankheitsbild
ist wahrscheinlich
die häufigsteUrsachepostoperativer
Morbiditätund MortalitätnachAnästhesiegesunderPferde,Es liegtdahernahe,eineweicheUnterlagezu verwenden,um die Kompression
zu vermindern.Es wurde die Häufigkeitder postnarkotischen
währendder Vollnarkose
Myopathienach EinsatzeinerPolyvinyl-Luftmatratze
von 1349 gesundenPferdenmit Halothanbestimmt.Der innereLuftdruckbetrugca. 25 - 30 mmHg,der eine Erhaltungder kapillärenPerfusion gewährleisten
soll. EineKontrolledes Druckeserfolgtedurch manuelleEinschätzung
der Zwischenräume.
Die Matratzeerwiessich als
praktikabelund haltbar(im Schnitt25 Pferde),wobei Löchereffektiv(weitere20 Pferde)mit Methylacrylat
geflicktwerden
oder Vinylflecken
konnten.Die durchschnittliche
Myopathie,wobei bei
Narkosedauerbetrug98 Minuten.0,9% der Pferdeentwickelteneine postnarkotische
O,7Vonur die unten liegendenKörperregionen
betroffenwaren.Die PferdehattenpräoperativkeinerleiStörungendes Bewegungsapparates
gezeigt,und die NarkoseverliefohneZwischenfälle.
Klinisch
war einegering-bis höchstgradige
Lahmheitbzw.fehlendeStehfähigkeit
zu beobachten,und die Pferdeerholtensich nach Stundenbis zu 4 Tagen.Bei Betroffensein
des M. tricepsbrachiiist ein tieferEllbogenauffällig,
Überkötendeutet auf Affektiondes M. quadricepshin und bei Erkrankungdes M, longissimusdorsi zeigendie Pferdeeine bilateraleharte
Schwellung.Die Pferdesind bewegungsunwillig,
Zur Verilizierung
der Ergebnissewäre eine direkteMessungdes Gewebsdruckesin den
Muskelndenkbar.
keywords:
postnarkotischeLahmheil,postnarkotischel.,4yopathie,
l\,4uskelschäden,
Pferd
Introduction
Post-anaesthetic
myopathyis probablythe most common
causeof morbidity
and mortality
in healthyhorsespresen(Dodmanet al. 1985,Klein 1990).The
ted for anaesthesia
reportedincidenceof post-anaesthetic
myopathyranges
from O.75o/o
to 6.40/o
of equineanaesthetic
cases(Mc Carvilleand Blais1986,Klein 1978,Richeyet al. 1990,Peek
1993);on cattleno dataareavailable.
It is generally
assumedthat pressureon the muscleswill
result in an impairmentof the circulation,creatingan
ischaemicconditionand cause myopathy(Lindsayet al.
1980,Weaveret al. 1984,Grandyet al. 1987,Lindsayet al.
1989,Serteynet al. 1990,Hennigand Court 1991,Young
1993,Flahertyet al. 1996).Reperfusion
of the ischaemic
musclespost-operatively
or by posturalchangesduring
anaesthesia,
resulting
in releaseof freeradicals,
couldexplain the musculardamage observedin equine postPferdeheilkunde
14
anaestheticmyopathy(Serleynet al. 1988,Serteynet al.
1990).
Lindsayet al. (1985)and Whiteand Suarez(1986)have
proventhat horsesin lateralrecumbency
on a paddedsurpressure
lessinterstitial
in the underfacehada significant
lyingtricepsmusclethanwhenthe horseswerepositioned
on a hardsudace.Thus,an adequatepaddingand careful
positioning
of the patientduringanaesthesia
appearto be
et al. 1996).Air mattresses,
of utmostimportance(Flaherly
thick foam (Flaherly,Nolanand Reid 1996)or waterbeds
(Lindsayet al. 1985)havebeenadvisedto be usedfor all
butveryshodprocedures.
This paperreportson the incidenceof post-anaesthetic
myopathyat the Departmentof Generaland LargeAnimal
sincethe startof the useof the
Surgery,
UtrechtUniversity,
polyvinyl
air mattress(Waffle@).
131
The Incidenceof Post-Anaesthetic
Mvopathvwith the Useof a StaticAir lvlattress
Materialsand Methods
Theoneroomairmattress
studiedis constructed
witha large
numberof holes(Fig.1),creating
cellswhichhavebroadintercommunications
for freetransmission
allowing
of pressure.
lt
is available
in various
sizes.Themattresses
usedin thisstudy
hada totallengthof 218cm anda widthof 88 cm.
tomidine l.V. (Domosedan@;
Smith Kline, Holland)or acepromazine(0.1 mg/kg)/methadon(0.1 mg/kg) l.V. (Stehnarcose@;A.U.V., Holland).Once sedation had taken effect
guaifenesine100 mg/kg as a 10% solution(Gujatal@;
Aesculaap 8.V., Holland)with thiopentone5 mg/kg (Nesdonal@,Rhöne-Merieux,Holland)was administeredintravenously to achieve inductionand lateralrecumbency.The
horses were intubatedand halothane(Albic,Holland)was
administeredin a mixture of oxygen and nitrousoxide
(600Ä/40%:SUmin) or 100o/ooxygen (SUmin)to maintain
anaesthesia.Anaesthesiawas monitored continuouslyby
clinicalexaminationand electronicaldevices(HewlettPackard l\/erlinMonitoringSystem@).
Fig.2:
Fig. 1:
The Wafflemattress
Ein Pferd in dorsaler Lagerung gebettet auf eine dreifach
zusammengelegteLuftmatratze.
Die Waffle-Matratze
Althoughin humanpatientsone mattressis sufficient
to
elevatethe patient,it becameclearthat the insufflation
pressure of 35 strokes of the Waffle MAD@
(Measured
Air Delivery
EHOB@)
is insufficient
for horsesof
about600 kg BW.Aftervarioustrials,the useof 2 three-folded mattresses
lyingnextto eachotherseemedto fuhction
well.The mattresses
wereeachinflated
withapproximately
20 strokes.
Underhalothaneanaesthesia
the patientswere elevated
fromthe hardsurfaceof the operation
tableand positioned
on the inflatedmattresses(Fig.2 and 3). A hand was
placedbetweenthe mattressand the surgerytable to
checkthe positionof the patient.The pressureinsidethe
mattress(25-30mm Hg measuredby useof a manometer)
shouldbe justenoughto allowa handto easilyslideunder
the buttocksof the animal.lf the pressure
was to low,the
mattress
couldbe easilyinflated
withthe lt/AD@.
Onlya minimalinflation
was neededto liftthe patient.lf the pressure
is too high,the air can easilybe released
throughthe inflationportwhichis locatedat oneendof the mattress.
Deflationis donerapidlyin 2 to 3 secondsby pullingthetab at
the port.Withthe three-folded
mattress
it is essential
to positionthe patientsuch,as allowaccessto the valveat any
time.
Patientswere anesthetised
followingstandardprocedures
usedin ourclinic.Premedication
consisted
of 5 mco/kode-
132
A horse in dorsal recumbencypositionedon the triple
folded air mattress.
Fig. 3:
A horse in lateralrecumbencypositionedon the triple
folded air mattress.
Ein Pferd in lateralerLagerung gebettet auf eine dreifach
zusammengelegteLuftmatratze.
positionof
Bodyweight,breed,history,surgicalprocedure,
patient
patient
the
duringanesthesia,
stability
of the
on the
pressure
mattress,
insidethe mattress
afterpositioning,
durationand courseof the anaesthesia
and the lifetime
of the
mattresses
wererecorded.The patientswereexaminedafter they stood in the recoverybox and effortsto ambulate
became coordinated.A post-anaesthetic
lamenesswas
Pferdeheilkunde
14
Astrid B.M. Rijkenhuizen and P. van Dijk
definedas myopathywhenthe horsesshowedclinicalsigns
In
of muscledysfunction
combinedwith muscular
swelling.
thesecases,the muscleswere hard on palpation,the patients were reluctantto walk, and appearedpainful.The
musclegroupsincludedand the durationof the lameness
were recorded.Transientknucklingat the fetlockswhile
attemptingto standwas not recordedas lameness.
Results
Mattress
The patientsstayedeasilyin position,becauseof the sufficientroughnessof the mattressand the fact that the matmattrestresswas largerthanthe patient.Two three-folded
ses and a headmattresswereof sufficientsizeto properly
supporlthe horse'swholebody and smallenoughnot to
wereeabe cumbersomefor the surgeon.The mattresses
sy to handleand desinfect.
One mattresscould be used for an averageof 25 horses
beforeleakageoccurred.Leakagewas generallyseen at
the sealof the holes,but couldalsobe the consequence
of
an inadvertentperforationby the surgeonwith a scalpel
bladeor towel clampforceps.The placesof leakagewere
For largerholesa vinyl patch
sealedwith methylacrylate.
was used. After repairthe mattressescould be used for
another20 horses.
Patients
with an average
In 1995 1349 horseswere anaesthesized
time of 98 min.Twelve(0.9%)horseshad proanaesthesia
blemsduringthe recoverybecauseof myopathyfl-able1).
Threeof the 9 frontlimbsconcerned
the upperlimb.All 12
horses(bodyweightbetween400 and 8a0 kg) were free
from clinicalevidenceof lamenessor musculardiseasebefore surgery.The meandurationof anaesthesia
in the 12
horsessufferingfrom myopathywas 150 min (90-265).
Anaesthesiawas uneventfulin all horses sufferinqfrom
myopathy.
The clinicalsigns varied from mild lamenessto severe
lameness
in whichthe horsewas unableto placeweighton
the involvedlimb.The horseswith tricepsbrachiimyopathy
stood with a characteristic
droppedelbow stanceof the
limb(Rijkenhuizen,
Keg and Dik 1994),andwere reluctantto
bearweighton the affectedlimb.Whenthe quadricepswas
involved,
the horseswereunwilling
to bearweighton the involvedlimband knuckledoverat the fetlock.Theclinicalappearancewas that of a femoralparalysis.
The horsewith a
longissimus
dorsiproblemwas reluctantto moveand had
bilaterally
very swollenand hard muscles.The recoveryof
the myopathytook betweensomehoursand 4 days.
Of 77 cattle(durationof anaesthesia:
average114 min) 1
bull (bodyweight70Okg;durationof anaesthesia
360 min)
tricepsmusclefor
developeda myopathyof the underlying
a few hours.
Tab. 1: Clinicaldetailsof the patientswith post-anaesthetic
myopathy,
Klinische
Befundeder Patienten
mit Myopathie
nachder Narkose.
Breed
Age(yrs) /t/eisht(ks) Surg.proc. Dur.An(min)Recumbency
Myopathy
Limb
Dur.of clinical
symptoms(hrs)
KWPN-
10
550
dentalsurg.
120
lat.
frontlimb
down
24
KWPN
4
599
dentalsurg.
170
lat.
frontlimb
oown
12
KWPN
6
500
CT-scan
150
lat.
hindlimb
oown
48
KWPN
7
600
woundhealing
160
lat.
frontlimb
oown
96
600
vascularsurg.
265
td t.
hindlimb
up
72
115
dor.
frontlimb
down
48
180
oor.
frontlimb
oown
48
hi ndl i mb
down
24
frontlimb
down
48
KWPN
1A
KWPN
B
colicsurg.
KWPN
5
^^ti^
uuilu
KWPN
7
400
15
840
Norw.fj.
B
429
sinusitis
110
td t.
frontlimb
up
12
KWPN
4
525
dentalsurg.
120
l^+
td t.
frontlimb
down
48
Hackney
6
M. longdorsi
down
12
Shire
KWPN
10
Friesian
horse
..^
^.
Dur g.
uterusrupture
uuilu
uuilu
Dur v.
Jur g.
120
200
90
602
cornearupture
75
480
arthroscopy
75
to L .
oor.
oor.
l^+
td L .
oor.
paralysis up
radial-nerve
myelomalacie
4 weeks
euthanasia
- KWPN:Dutchwarm-blood
Pferdeheilkunde
14
133
The Incidenceof Post-Anaesthetic
Myopathywith the Use of a StaticAir Mattress
Discussion
Thistype of mattresswas selectedto be testedfor use in
horses,becausehumanliterature,
basedon the evaluation
of CT-scansof subjectssupportedby varioustypesof beddings,indicatesthat the useof Wafflerpolyvinyl
air mattresses (EHOB,Indianapolis,
U.S.A)resultsin a significant
re(Connerand Clack7993)and may
ductionof compression
resultin a lowerincidence
rateof ulcers.Animalmusclesor
deep tissuesare more sensitiveto pressurethan skin and
more proneto undergonecrosis(Nolaand Vistnes1980,
Daniel, Wheatlyand Priest 7985). Thereforethe use of
these mattressesseemedindicatedfor animals.Furthermore,the Wafflermattressis usedwith a verylow intraluminalstaticair pressure.Staticair is the onlymediumthat can
perpendicular
pressureon the body
delivernon-gradient
and a low pressureis essentialin preventingmusclecell
damage(Kosiak7961).
The incidenceof 0.9% of post-anaesthetic
myopathycan
be consideredto be low when comoaredto the values
(0.75Io 6.4%).lfonlythe undermentioned
in the literature
lyinglimbandthe backproblemsareconsidered,
thefigure
evendecreases
to 0.7%.
It may be concludedthat the practicaluse of the mattresses was good and the lifetime of the mattresses
was sufficientto justifythe costs.Thesystemofferspressurecontrol
and is easilycleaned.The easymoisturedrainagefromthe
patientthroughthe holesis judgedto be an additional
adprovethe effectof the use of the
vantage.To scientifically
Wafflermattressesin reducingthe incidenceof myopathya
controlstudy shouldbe conductedwith musclepressure
measurements.
The constantlow pressuremattressesare
intendedto providean interfacesurfacepressureoverthe
wholeundersurface
of the body belowthe averagecapillary
closingpressureof 32 mm Hg (Connerand Clark 1993).
Whetherthe interfacepressurewe measuredis reallya true
reflection
of thetissuepressure
hasstillto be determined.
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AstridB.M. Rijkenhuizen
Departmentof Generaland Large animalSurgery
Utrecht University,
Yalelaan12
3584 CM Utrecht
The Netherlands
Tet.(00s1)s0 253 1s 50
Fax (0031)30 253 7970
emaiI [email protected]
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