Veterinary anesthesia and pain management secrets

343 Pages·2002·15.4 MB·English

by  Stephen A Greene

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Libraryof Congress Cataloging-in-Publication Data
Veterinary anesthesia and pain management secrets/ edited by Stephen A. Greene.
p. em. - (The Secrets Series®)
Includesbibliographical references (p.).
ISBN 1-56053-442-7(alk paper)
I. Veterinaryanesthesia-Examinations, questions. etc. 2.Pain in animals
Treatment-Examinations, questions, etc. I.Greene, Stephen A., 1956-11. Series.
SF914.V48 2002
636089'796'076--dc2I 2001039966
VETERINARY ANESTHESIAAND
PAIN MANAGEMENT SECRETS ISBN 1-56053-442-7
© 2002by Hanley& Belfus, Inc. All rights reserved. No part of this book may be repro
duced, reused, republished. or transmitted in any form, or stored in adatabaseor
retrieval system, without written permission of the publisher
Last digit is the print number: 9 8 7 6 5 4 3 2
CONTRIBUTORS
G.John Benson,D.V.M.,M.S., D.A.C.V.A.
Professor,Departmentof VeterinaryClinical Medicine, University of IllinoisCollege ofVeteri
naryMedicine, Urbana, Illinois
NigelA.Caulkett,D.V.M.,M.V.Sc.,D.A.C.V.A.
Associate Professor, Department of Small Animal Clinical Sciences, University of
Saskatchewan, Saskatoon, Saskatchewan,Canada
SophieCuvelliez,D.M.V.,M.S., D.A.C.V.A., D.E.C.V.A.
Professor, Department ofClinical Sciences, VeterinaryMedicine, Universite de Montreal, Saint
Hyacinthe, Quebec, Canada
ThomasK. Day, D.V.M.,M.S., D.A.C.V.A., D.A.C.V.E.C.C.
Emergency and Critical Care Veterinarian, Louisville VeterinarySpecialty and EmergencySer
vices,Louisville, Kentucky
Tom Doherty,M.V.B.,M.Sc., D.A.C.V.A.
Associate Professor, Department of Large Animal Clinical Sciences, The University of Ten
nessee,College ofVeterinaryMedicine, Knoxville,Tennessee
Doris H. Dyson,D.V.M.,D.V.Sc.,D.A.C.V.A.
Associate Professor, Department of Clinical Studies, Ontario VeterinaryCollege, University of
Guelph,Guelph, Ontario, Canada
JenniferLindaFujimoto,D.V.M.,D.A.C.V.A.
SeniorVeterinarian,AnimalCare Program. UniversityofCalifornia atSanDiego,LaJolla,Cal
ifornia
David S.Galloway, D.V.M.,M.M.A.S.
Major,U.S.ArmyVeterinaryCorps; Resident ofSmallAnimal Surgery,DepartmentofClinical
Sciences, College ofVeterinaryMedicine, Oklahoma State University,Stillwater,Oklahoma
StephenA.Greene, D.V.M.,M.S., D.A.C.V.A.
Associate Professor ofVeterinaryAnesthesia. Department ofVeterinaryClinicalMedicine, Uni
versityof IllinoisCollege ofVeterinaryMedicine, Urbana, Illinois
KurtA.Grimm,D.V.M.,M.S., D.A.C.V.A., D.A.C.V.C.P.
VisitingAssistant Professor, Department ofVeterinaryClinical Medicine. University of Illinois
CollegeofVeterinaryMedicine, Urbana, Illinois
TamaraL. Grubb,D.V.M.,M.S., D.A.C.V.A.
Assistant Professor,CollegeofVeterinaryMedicine, Oregon StateUniversity,Corvallis,Oregon
RalphC. Harvey,D.V.M.,M.S., D.A.C.V.A.
Associate Professor ofAnesthesiology, Department of Small AnimalClinical Sciences, Univer
sityofTennesseeCollege ofVeterinaryMedicine, Knoxville,Tennessee
TerrellG. Heaton-Jones,D.V.M.
Researcher, College ofVeterinaryMedicine, University of Florida, Gainesville, Florida
ix
x Contributors
JanaL. Jones, D.V.M.,D.A.C.V.A.,D.A.C.V.E.C.C.
AssistantProfessor,Department ofLargeAnimalClinical Sciences, College ofVeterinaryMed
icine, University ofTennessee, Knoxville,Tennessee
Robert D.Keegan,D.V.M.,D.A.C.V.A.
Associate Professor, Anesthesia Section Head, Department of Veterinary Clinical Sciences,
WashingtonState University,Pullman, Washington
Lisa S. Klopp, D.V.M.,M.S., D.A.C.V.I.M. (Neurology)
Assistant Professor, Department of VeterinaryClinical Medicine, University of Illinois College
ofVeterinaryMedicine, Urbana, Illinois
JeffC.H. Ko, D.V.M.,M.S., D.A.C.V.A.
Associate Professor ofAnesthesiology, Department of VeterinaryClinical Sciences, College of
VeterinaryMedicine. OklahomaState University,Stillwater, Oklahoma
KrisT.Kruse-Elliott,D.V.M.,Ph.D.,D.A.C.V.A.
Associate Professor, Department of Surgical Sciences, University of Wisconsin, Madison,
Wisconsin
Lynne I. Kushner,D.V.M.,D.A.C.V.A.
StaffAnesthesiologist, DepartmentofClinical Sciences,Veterinary Hospital ofthe University
of Pennsylvania; University of Pennsylvania School of Veterinary Medicine, Philadelphia,
Pennsylvania
Leigh A.Lamont,D.V.M.
Resident inAnesthesiology, Department of VeterinaryClinical Medicine, University of Illinois
College ofVeterinaryMedicine, Urbana, Illinois
Kip A.Lemke,D.V.M.,M.S., D.A.C.V.A.
AssociateProfessorofAnesthesiology,AtlanticVeterinaryCollege,UniversityofPrinceEdward
Island,Charlottetown,Prince Edward Island,Canada
Khursheed Mama,D.V.M.,D.A.C.V.A.
Assistant Professor, Department of Clinical Sciences, Colorado State University, Fort Collins,
Colorado
ElizabethA.Martinez, D.V.M.,D.A.C.V.A.
Associate Professor, Department ofSmallAnimal Medicine and Surgery,College of Veterinary
Medicine,TexasA& M University,College Station,Texas
SheilaM. McCullough,D.V.M.,M.S., D.A.C.V.I.M.
Clinical Assistant Professor, Department of VeterinaryClinical Medicine, University of Illinois
College ofVeterinaryMedicine, Urbana, Illinois
RobertE.Meyer, D.V.M.,D.A.C.V.A.
AssociateProfessor.DepartmentofAnatomy,Physiological Sciences,andRadiology,NorthCar
olinaState University College ofVeterinaryMedicine, Raleigh, NorthCarolina
LuisitoS.Pablo,D.V.M.,M.S., D.A.C.V.A.
Associate Professor, Department of Large Animal Clinical Sciences, University of Florida,
Gainesville, Florida
Contributors xi
JaneQuandt,D.V.M.,M.S., D.A.C.V.A.
Assistant Clinical Specialist inAnesthesiology, Department of Small Animal Clinical Sciences,
CollegeofVeterinaryMedicine. VeterinaryTeaching Hospital, University ofMinnesota, SI.Paul,
Minnesota
David C. Rankin, D.V.M.,M.S., D.A.C.V.A.
StaffAnesthesiologist,Wisconsin Veterinary Referral Center, Wankesha,Wisconsin
ThomasRiebold,D.V.M.,D.A.C.V.A.
Professor, Department of Large Animal Clinical Sciences. College of Veterinary Medicine.
Oregon State University, Corvallis, Oregon
SheilahA.Robertson,B.V.M.S.,Ph.D.,D.A.C.V.A.
Associate Professor, Section of Anesthesia and Pain Management, University of Florida,
Gainesville, Florida
YvesRondenay,D.M.V.
Clinical Instructor. VeterinaryTeaching Hospital. Universite deMontreal, Quebec, Canada
JulieA.Smith,D.V.M.,D.A.C.V.A.
Hospital DirectorandChiefofAnesthesia,lAMS PetImaging. Vienna,Virginia
LesleyJ. Smith,D.V.M.,D.A.C.V.A.
Clinical Assistant ProfessorofAnesthesiology, Departmentof Surgical Sciences, School ofVet
erinary Medicine, University ofWisconsin, Madison, Wisconsin
WilliamJ.Tranquilli,D.V.M.,M.S., D.A.C.V.A.
ProfessorofClinical Medicine(Anesthesiology and Pain Management),Department ofClinical
Medicine, University ofIllinoisCollege ofVeterinaryMedicine; University ofIllinoisVeterinary
Medicine Teaching Hospital, Urbana, Illinois
LoisA.Wetmore,D.V.M.,Sc.D., D.A.C.V.A.
Assistant Professor, DepartmentofClinical Sciences,TuftsUniversity SchoolofVeterinaryMed
icine, North Grafton. Massachusetts
DeborahV.Wilson,B.V.Sc.,M.S., D.A.C.V.A.
Associate Professor, DepartmentofLargeAnimal Clinical Sciences. Michigan State University,
East Lansing, Michigan
PREFACE
It is my sincere hope that the reader will find the unique question-and-answer
approach to be a breath offresh air when compared with previously published texts on
veterinaryanesthesiaand pain management.The contributingauthorsare noted experts
invarious veterinary medical specialties, includinganesthesiology, clinical pharmacol
ogy, critical care, internal medicine, and neurology. Each has included subject matter
that is ofclinical relevance and interest. Iam grateful for their diligent labors and will
beforever in their debt.
As in other Secrets volumes, this book has been presented in an informative and
easily understood style. It has been organized into nine sections: Patient Management,
Patient Preparation, Pharmacology, Patient Monitoring, Perianesthetic Complications,
Anesthesia and Systemic Disease, Special Anesthetic Considerations, Regional Anes
thesia, and Pain Management for Small Animals. Each section contains salient infor
mation related to anesthetic managementofsmall and large domesticspeciesas well as
amphibians, birds, camelids, laboratory animals, reptiles, and other wild animals. The
inclusion of concepts and techniques related to pain management addresses the vital
role ofthis increasingly emphasized aspect ofveterinary medical care both in and out
ofthe surgical theater.
I want to acknowledge William Lamsback and Mary Beth Murphy at Hanley &
Belfus for offering theirencouragement and inspiration to make this book more than a
virtual reality.
Finally, I would like to dedicate this book to my colleagues, friends, and family
(especially Erma, Kaitlin, and Jared) for their unwavering support ofmy professional
effortsand to the memoryofmy father, Dr.DaryleE.Greene, who recognizedthe value
ofpersistence in all worthwhileendeavors.
Stephen A. Greene, DVM, MS, DACVA
xiii
I. Patient Management
I. AIRWAY MAINTENANCE
Jane E.Ouandt, DVM., M.S., DACVA.
1. Whatare the advantages toendotrachealintubationversus aface mask for maintain
inginhalantanesthesia?
o Maintenance ofapatent airway.
o Improvedefficiency ofdelivery ofoxygen andanesthetic gases.
o Decreased exposure ofwastegases topersonnel.
o Intubation improves theefficiency ofrespiration byreducing theamountofdeadspacewithin
therespiratory passages.Theendoftheendotracheal tubeshouldbeattheleveloftheanimal's
incisorstoavoidendotrachealtubedeadspace.
o Respiratory support inthe form of intermittent, positive-pressure ventilation is possible with
intubation.Thisisrequired foranimals undergoingthoracotomy ordiaphragmatic herniarepair
orreceiving aneuromuscularblocking agent.
o An endotracheal tube with a cuff will reduce the risk of aspirating vomitus, blood, flush,or
other material that may runintotheoralcavity and breathing passages.
Animals undergoing general anesthesiashould beendotracheallyintubated.
2. Whatisthe procedurefor endotrachealintubationinthe dogor cat?
o Anendotrachealtube.Havemorethanonetubeinvaryingsizesandinappropriatelengths.The
tubecuffs should bechecked toensure there are noleaks. Notetheamount ofairrequiredto
fillthecuff.
o Steriletubelubricant suchaslidocainegelorK-Yjelly.Whenlubricating asmallendotracheal
tube,besure thelubedoes notobstruct thetubeopening.
o Lidocainespray(forcats)or I%lidocainesolutiondrawnintoasyringe.0.1mlissquirtedonto
thelaryngeal areatodecrease theriskoflaryngospasm. Avolumeof0.1to0.2mloflidocaine
issufficient, asexcessiveadministrationcan betoxic.
o Gauze tietohold theendotrachealtubeinplace.
o Laryngoscopeoragood lightsource tovisualize thelaryngeal area.
3. Whatisthe procedureforendotrachealintubationinthedogorcat?
Whentheanimal, insternal orlateral recumbency. reachestheappropriate planeofanesthe
sia and there are no signs of resistance such as gagging, swallowing, or chewing motionupon
opening the mouth, theanimal isready to be intubated. Once the mouth isopened, the neckis
extended so the head and neck are in a straight line. The upperjaw is held stationary,lips are
pulleddorsally,andthelowerjaw ispusheddownwiththetonguepulledforwardanddown.Use
cautionanddonotcutthetongueontheteethorpullthetongueexcessively.whichcoulddamage
thenerves.
Theanesthetist usingthelaryngoscope orotherlightsourceshouldbeabletoseetheepiglot
tisoverlying the trachea. The laryngoscope bladeor tipof theendotracheal tube isusedtodis
engage thesoftpalate fromtheepiglottis. The bladecanthen beusedonthebackofthetongue.
adjacent tothebaseoftheepiglottis. When pusheddownward, theblade pullstheepiglottisfor
wardanddown, allowing theentrance tothetracheatobe visualized.
Theendotracheal tubeisinsertedpastthevocalfoldsandintothetrachea.Incats,intubation
isbest done by advancing the tube when the vocal cords separate and the glottisopens. Don't
2 Airway Maintenance
forcethetubepastthevocalcords ifresistance isencountered:gentlyrotatethetubeandadvance.
The curve of thetube should matchthe patient'sneck when intubation iscomplete.
4. Howcan useofastylet help inendotrachealintubation?
Asmall flexible endotracheal tube may bend during insertion. The use of a stylet, a thin
metal rod or thick aluminum wire, inserted into the tube will prevent bending. The end of the
stylet should not protrude beyond theend ofthe tube. as itmay traumatize the laryngeal tissue.
Once thetube isinthetrachea, thestylet must beremoved, as itwillobstruct theairflow.
5. Describe correctplacementofthe endotrachealtube. Howisthe tube secured?
Once the tube iscorrectly placed the tube emerges from the glottis with the tip no further
than the carina. The endotracheal tube connector should be at the level of the incisor teeth to
avoidexcessive deadspace.Vocalizationisimpossibleifthetubeisproperlyplaced.Iftheanimal
whinesor makes vocal sounds, the tube isintheesophagus.
The tube isheld inplace withasnuggly tied piece of gauze.The tieshould besnug topre
vent slipping. which can occur when the tube becomes wet with saliva or other liquid. such as
flushorblood.Thetieendsarethenpassedbehindtheearsorbehindthecanine teethandsecured
withabow knot.
6. Howmuch airshould beputin the cuffofthe endotrachealtube?
The reservoirbagisgently squeezed to 20em HoOandtheanesthetist listens forthesound
ofleakingair exiting theoral cavity.The cuff isinflated onlyuntilthere isnolongeraleak.The
cuffshould beinflated incrementally toprevent overinflation. Iftheleak islarge,considerrein
tubation withalargertubeorcheck tomakesurethetubeisnotintheesophagus. Excessivepres
sure inthecuffmaycause ischemic injury and perhaps leadtotracheal stricture, tracheal ulcer
ation, tracheitis, hemorrhage, tracheomalacia,fibrosis. or stenosis.
Asurgeryoflongduration willrequire theendotrachealtubetobeinplaceforlengthytimes.
Toavoidconstant pressure ofthecuffonthesameareaofthetrachea, thecuffshouldbedeflated
every2hours,thetuberepositionedslightly,andthecuffreinflated.This willhelppreventpoten
tialpressure necrosis ofthetracheal mucosa.
7. Whatisthe advantageofacuffed versus a noncuffed tube?
Thecuffhelpstopreventleakageofwastegases.Itwillalsoreducetheriskofaspiration.Ani
malsintubatedwithcuffedtubesarepreventedfrombreathingroomair,whichmayotherwiseenter
byflowfromaroundtheoutsideofthetube.Ifsignificantamountsofroomairarebreathedin.itis
difficulttomaintaintheanimalatanadequateanestheticdepth.astheairdilutestheanesthetic.
8. Whatprecautionscan betaken toavoid problemswith endotrachealintubation?
Use a sterile or thoroughly disinfected endotracheal tube for each patient to prevent the
spread of infectious disease.
The endotracheal tubeshould belubricated withsterile xylocaine or K-Yjelly. Avoidusing
a lubricant containing benzocaine, as this can lead to a dose-dependent methemoglobinemia,
whichdoes notbindoxygen.
Intubation may stimulate the activity of the vagus nerve, increasing parasympathetic tone.
especially indogs.This mayresultinbradycardia.hypotension. andcardiac dysrhythmias. Ifthe
animal hasanunderlying cardiovasculardisease, cardiac arrest mayoccur.Atropineorglycopyr
rolate, an anticholinergic, given as part ofthe premedication can be helpful in preventing the
parasympathetic stimulation.
Do not beforceful in the intubation. as thiscan damage the larynx, pharynx, or soft palate
and lead totissue edema. Ideally,the tipof theendotracheal tube should be pastthelarynx and
notbeyond the thoracic inlet. Ifthe tube isadvanced toofar,it mayenter one bronchus, result
ingin ventilation toonly one lung. Premeasure the length of theendotracheal tubeand thedis
tance between the nose and the thoracic inlet prior toanesthesia. The end of the tube should be
atthelevelof theanimal's incisors.
Airway Maintenance 3
To avoid esophageal intubation, visualize the endotracheal tube going into the trachea.
Esophageal intubation will leadtohypoxemiaandan awakening patient.
Do not overinflate the cuff of the endotracheal tube, or pressure necrosis of the tracheal
tissuemayoccur.
Watchthattheendotrachealtube does not become obstructedwithsaliva, blood,orforeign
materialor become kinked.
9. Brachycephalic animals such as bulldogs, pugs, and Persian cats can be difficult to
intubate.Whatspecial considerationsarethereforairwaymanagementinthese breeds?
There arefourcommonabnormalities withbrachycephalicbreeds:
• Elongated soft palate
• Everted laryngeal saccules
• Stenoic nares
• Hypoplastic trachea
These animals also have redundant pharyngealtissue that makes visualizing theairway dif
ficult. An array of endotracheal tubes in varying sizes should be readily available. The trachea
maybe smaller than the size of the animal would indicate. Preoxygenate toincrease the safety
marginfor intubation. These breeds frequently have high vagal tone, andintubation stimulation
maycause avagal reflex andbradycardia. Preanestheticadministrationofananticholinergic can
helpprevent thisfromoccurring.
Inrecovery,leave theendotracheal tubeinforaslongaspossible. Onceextubated,theseani
malsneedclose monitoring toensure thattheairwaystays patent. Keepingtheanimal'sheadand
neckextended willhelppreventtheredundant tissuefromobstructing theairway.Alwayskeepthe
propersizeofendotrachealtubeneartheanimal'scage incase reintubation becomes necessary.
10. Arethereany special considerationsfor the intubationofcats?
Cats have anarrow glottis that iseasily traumatized; usecare when intubating. Ifthelaryn
geal tissues are irritated during intubation, laryngospasm-reflex closure ofthe laryngeal carti
lages-may occur. This can cause blockage of the airway. To prevent laryngospasm, use lido
caine spray on the larynx and lidocaine gel on the endotracheal tube to help desensitize the
laryngeal tissue. Useagentle intubation technique; advance thetube whentheglottis isopen.
Thecat ismore prone tolaryngospasm with inadequate anesthetic depth.The laryngoscope
isusedtodepress the tongue and not topull theepiglottis forward anddown. The blade should
nottouch theepiglottis,asthiscan cause trauma andedema.
Aguide tube,suchasa5to8Frenchcanine urinarycatheter, thatextends pastthecuffedend
oftheendotracheal tube for adistance of 2to3cmcarrbe used tohelp make intubation easier.
Passthesmall catheterfirstand thenthread theendotrachealover thecatheterintothetrachea.
11. Whatshould youdoifthe cat has alaryngospasm?
Donotstimulatethe larynx further; stop trying tointubate.
Supply oxygen bymask, sothat anyairthatenters thetrachea isoxygen-enriched.
Tryone moredose oflidocainesprayonthelarynx. Ifthespasm does notrelaxwithin 10to
20seconds, trydeepeningtheanesthetic plane, oruseaneuromuscularblocking agent.Aneuro
muscular blocking agent willcause relaxation ofthetissues, butalsoapneadue totheparalysis,
sointubationmustbedone immediately.
Do notforce intubation, asthiscan damage the mucous membranesand larynxand leadto
edema and then the danger of obstruction after extubation. It is also possible to penetrate the
pharyngeal wallwith forceful intubation.
Youcan secure atemporary airway byplacing a 14-gauge needle orcatheterinthetrachea
percutaneously. Ifallelsefails, perform atracheostomy.
12. When should the endotrachealtube beremoved?
Theendotrachealtubeshouldberemoved whentheanimal regainstheabilitytoswallowand
protect itsairway. Do not allow the patient tochew the tube inhalf and aspirate thedistal half.
4 Airway Maintenance
This will necessitate reanesthetizing theanimal to retrieve the tube, which is usually lodged at
thecarina.Care mustalsobetakenthatananimal withincreasedjaw tonedoes notbitedownon
thetubeandcreate anobstruction.
Followingadentalorother procedure inwhich bloodorfluid ispresentintheoralcavity,be
suretheoralcavity iswipedcleanof anymaterialtheanimalcouldaspirate,suchasgauze,tissue
fragments.andbloodclots.Usealaryngoscopetofullyvisualizethemouthanduppertrachealarea.
Extubation can be done with the tube cuff partially inflated to help act as a wedge and
remove debris in the upper trachea. Do not leave the cuff fully inflated, as itcan tear tracheal
mucosaanddamage thevocalcords. Oncetheanimal isextubated. makesureitisbreathing nor
mally.Itmay help toextend theheadand neck tomaximize the integrity oftheairway.
In the cat, don't delay extubation, as there can be the risk of hyper-responsive airway
reflexes. laryngospasm, retching, orvomiting.
13. Whatarethe indicationsfor performinga tracheostomy?
• Torelieve anupper respiratory tract obstruction
• Tofacilitate removal of respiratory secretions
• Todecrease dead space
• Toprovide aroute for inhalant anesthesiawhen oral orfacial surgery iscomplex
• Toreduce resistance torespiration
• When youare unable toorally intubate
• Toreduce theriskofclosed glottis pressure, orcough, following pulmonary orcranial surgery
• Tofacilitate artificial respiration
14. Whatisthe techniquefor doing atracheostomy?
Make a midline skin incision on the ventral neck equidistant from the larynx and the
manubrium. Partthetwosternohyoidmuscles onthemidlineandcontinue bluntdissection down
tothetracheal rings.Makeanincision transverse between therings;keeptheincisionsmall,only
bigenough forthe tracheostomytube.Alternatively, makealongitudinal incision toinclude two
or three tracheal rings. Don't place the incision too close to the first tracheal ring, or it could
potentially damage thecricoidcartilageand lead tosubglottic laryngeal stenosis.
Place stay sutures around thetracheal ringadjacent tothe incision oneither sideofthesur
gical opening. The sutures will aid in placementofthe tube and are left in, labeled cranial and
caudal, tohelp whenthe tubeisroutinely replaced orcleaned, or ifitgetsdislodged.
The tube ideally istwo-thirds tothree-fourths ofthe tracheal diameter. withahigh-volume.
low-pressurecuff. Inflate thecuffonly as needed toprevent a leak withpositive pressure venti
lationandtohelppreventaspiration. Ifaspecifically designed tracheostomy tubeisnotavailable,
anendotracheal tube can be used; itmay need tobecut soit isshort enough that itdoes notgo
intoone bronchus.
Fasten the tube in place by tying itaround the neck with umbilical tapeor gauze. The soft
tissue isloosely approximatedwithabsorbablesuturesandtheskinisclosed withnonabsorbable
sutures. It is important toallow any air escaping around the tube to vent to theoutside and not
accumulate underthe skin.
IS. Whatisthe postoperativecareofthe tracheostomy tube?
The lumen of the tracheostomy tube must be regularly cleaned toprevent obstruction with
dried bloodormucus.The tube should besuctioned frequently, maybeasoftenasevery 30min
utes after the initial placement, then decreasing to hourly and then to every 2 to4 hours as the
productionof secretions lessens. Suctioningofthe tube and airways isdone using asoft sterile
rubberorvinyltubewithanend-hole.Thesuctioncanbecontrolled usingathumbportorT-con
nector to allow application of intermittent suction. Suctioning must be intermittent, as continu
oussuction willleadtoatelectasisandhypoxemia. Oxygenatetheanimalfor5to7minutes with
100%oxygen prior to and after suctioning. After suctioning, give two to four positive pressure
ventilations tohelpopen thelowerairways.
AirwayMaintenance 5
Humidificationofthetubeisimportant toprevent thedrying ofsecretions thatcanblockthe
tube.Humidification can bedone witheitheracommercial humidifieror byinjecting I to5ml
ofsterilewater intothetubeevery hour.Manytracheostomytubescome withaninternalcannula
thatcan be removed, cleaned, and resterilized, making for easier maintenance. The cannula is
changed every 4 hours; the tracheostomy tube itself ischanged every 24 to48 hours ifthere is
no inner cannula. Secretions and mucus can adhere to the inner cannula or tube and lead to
obstruction oftheairway, which necessitatesthereplacementofthetubeorcannula withaclean
one.The tube requires frequent monitoring. asobstructioncan lead todeathofthepatient.
There ismajor risk for nosocomial infection when using tracheostomy tubes.therefore ster
iletechnique must beused forsuctioningandchanging ofthetube.
16. Howshould the tracheostomy tubeberemoved? When isthis done?
Changingthe tracheostomy tube can bedangerous ifthe newtube isnotplaced inatimely
fashion. It is helpful to oxygenate the animal prior to tube removal and to use the sutures that
werepreplacedon the rings of the trachea cranial andcaudal totheopening inthetrachea.The
suturesshouldbelabeledascranial andcaudal andareusedtogently retracttheringsandtoexte
riorizethe trachea tomake theopening largerandeasiertosee. Ifthetracheostomy tubecannot
bere-inserted, oral intubation can bedone to establishanairway.
The tracheostomy tube can be removed when you believe that the animal is capable of
returning tonasalormouth breathing. Tohelpdeterminewhether theanimalcanbreathe,deflate
thecuff on the tube and occlude the tube opening. This technique isdangerous unless thetube
allowssufficient airtoflowaround thetube.Alternatively, remove thetubeandclosely monitor
the patient and re-intubate if necessary. Ifthe animal cannot maintain normal breaths, thetube
mustbe leftinplace.
Following tracheostomy tube removal, the animal must remain under close observation for
several hours. A new tube must be ready for replacement if the animal's breathing becomes
decompensated. Once itissafefortheanimal toremainextubated, thesiteisallowedtohealin7
to 10days bysecond intention, asprimary closure maypredispose tosubcutaneous emphysema.
17. Whatarearmoredendotrachealtubes?
Armored orreinforced endotrachealtubesaredesigned withhelicalwireorplasticimplanted
withinthe walls toprevent kinking ofthe tube and obstructionofthe airway whenthepatient's
headorneckisflexed.These tubesareusedwithophthalmicsurgery.headandnecksurgery.cer
vical spinal taps,oral surgery.orany procedure inwhich the airway maybecome kinked.
The armored tubes havethicker walls than astandard tube with asmaller internaldiameter.
sotherewillbeincreased resistance toairflow.These tubes shouldbeusedonlywhennecessary.
Theyareveryflexible andtherefore moredifficult toplace.Astyletorguide tubewillhelpfacil
itateinsertion.
18. Whatspecial risk accompanieslasersurgery?Whatisthe best precaution?
Fire. Lasercancutthrough theendotrachealtubeorignite thetube,andthefirecanbecome
blowtorch-likeinitseffect. Heat, flame, and toxic products can beputdown intothepulmonary
parenchyma.
Aredrubber endotrachealtube ismoreresistant toignition and willproduce lessdebrisand
inflammation.
19. Howcan the tubebeprotectedagainstthis risk?
When notusingaredrubberendotracheal tube.protectthetubebywrapping withaluminum
orcopperadhesive-backedtape.The tapewillreflect thelaser.butmakesuretheadhesive isnot
flammable. One type of tape that can be used is self-adhesive 3M number 425 aluminum foil
tape. Clean and dry the tube tobe taped and wipe itwith alcohol to remove residue sothat the
tape will stick. Cut the tape at angle of 60degrees with the cut edge aligned with theproximal
endofthecuffjunction.Wrapthetubefrom thecuff uptothepilottube inaspiralfashionwith