Evaluation of systemic and Splanchnic visceral Oxigen Variables in dogs with Surgically induced Gastric-Dilatation-Volvulus (GDV)

8/3/2019 Evaluation of systemic and Splanchnic visceral Oxigen Variables in dogs with Surgically induced Gastric-Dilatation-Vo

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Evaluation of Systemic and SplanchnicVisceral Oxygen Variables in Dogs WithSurgically Induced GastricDilatation-VolvulusJ. Komtebedde, DVMDepartment of Surge~W.G. GuitiOrd, BVSC,BPhilDepartment of Physiological Sciences

S.C. Haskins, DVM, MSJ.R. Snyder, DVM, PhDDepWment of SurgeySchool of Veterinary MedicineUniversity of California, Davis

Gastric dilatatiomvoivulus (GD~ was surgically induced in ten dogs to evaluate changes in thefoiiowing variabies: sutface Wgen partibipmssure (I%@) ofsphmhnk viscera systemic 02 ~sPOff(D@), systemic 02consumpti~ (l@), and02ubYization fetio (02UR). Thesevariabieshavebeen shownto be closely correlated to tissue viabiiity and patient sundvai in a variety of ischemic disorders.Gastric dilatation-voivuius was corrected atler 2.5 houm and the dogs were given iactated Ringerssoiution (90milkg) over30 minutes (resuscitation). At6 hours, tie dogs were euthanized withoutrecoveryfrom anesthesia.Gastric dilatation-voivuius resulted in a significant (p c 0.05) decrease of spianchnic tiscefal Ps02and D02 and a significant (p < 0.01) increase in 02UR. Systemic 02 consumption did not changesignificantly during the experiment.Resuscitation resulted in a transient and significant (p < 0.05) increase in Ps02 to baseiine, exceptfor hqxtic Ps02. Systemic 02 transpott and 02UR increased significantly (p < 0.001) compared tobaseiine. Surface oxygen pattiai pressure and D02 were signifimnW (P c 0.05) beiow baseiine at theconchwon of the experiment, whereas 02UR remained significantly (p < 0.05) above baseiine. Surfaceoxygen partieipressure of aii spianchnic viscera, except iiver psOa correlated M D02 ~rougho~ weexperiment (r: 0.69-0.78).Assessment ofDO~ V02 and ONRmaybe used to evaluate efficacy of cardiovascuiarsupportduringcorrective surgery for canine GDV.

IntroductionViability of cells, tissues, and organs depends upon

maintaining an appropriate balance betvveen oxygendelivery and oxygen consumption. These oxygen vari-ables are usually not assessed in veterinary medicine,although substantial clinical evidence in humans sug-

WX byhoCompanionnimal I.abom@ Fund, Unkemiiy d Calfomi%SchOOl of Va-hary MOdidnqOds, Cdlfomia-16.

gests that variations in these parameters are stronglyrelated to survival and death.2Doppler ultrasonography, pulse oximetty, electro-

myography, and recently, surface oximetry are current-ly under experimental and clinical investigation for theassessment of tissue viability= Wtih the exception ofsurface oximetty, none of these techniques directly as-sess tissue oxygenation. Surface oximetry reflects thebalance between tissue oxygen delivety and oxygenconsumption by measuring the partial pressure of oxy-gen (PsOJ on the surface of tissues.3 Sudace oximetry

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-n Varlablaa in GDV

is being used extensively in humans for continuoustranscutaneous/transconjunctival oxygen partiai pres-sure measurements to evaluate systemic oxygendelivery. The value of Ps02 in the assessment of vis-ceral organ viability and function (intestine, iiver, andheart) has been documented experimentally.*14 Therelationship between PsOZ of splanchnic viscera andsystemic oxygen variables has not been reported inthe dog. Knowledge about this reiation maybe impor-tant for the interpretation of iocal PSOZ data obtainedin patients with cardiopulmonary derangements.Gastric diiatation-voivuius (GDV) is associated with

a high degree of morbidity and mottaiity as the resultof hypovolemic shock, splanchnic visceral, and myo-cardiai ischemia.l&la An accurate assessment of gas-tric and intestinal viability during surgical correction ofGDV is important for patient surdval. Assessment ofthe adequacy of reperfusion of other visceral organs,such as the pancreas and iiver, may influence manage-ment and assist prognostication. The use of standardclinical criteria and intravenous fluorescein fluores-cence to predict gastric and intestinal viability can beunreliable.ig Surface oximetry may be a useful objec-tive technique to assess visceral organ viability in dogswith GDV intraoperativeiy.34The objectives of this study were:q to estabiish reference vaiues for PsOZ of several

spianchnic viscera in halothane-anesthetized dogs in-spiring 100% 02;q to quantitatively assess oxygenation of spianchnicviscera with surface oximetry in an experimental modeiof canine GDV

q to determine the influence of GDV on systemicoxygen variabieq and

q to investigate the strength of potential correlationsbetween PSOZvalues of splanchnic viscera and hemo-dynamic and systemic oxygen variables.

Materials and MethodsANIMALS AND ANIMAL PREPARATIONTen unconditioned mongrel dogs (mean body

weight 23.8 & 3.6 kg) were attained from the AnimalResource Sewice, University of California at Davis. Theexperimental protocol was approved by the AnimaiUse and Care Committee.Food was withheld for 12 hours prior to the experi-

ment. No anesthetic premeditation was given. Anes-thesia was induced and maintained with haiothane(Halothane:Halocarbon Laboratories, Inc., Notth Aug-usta, N.C.). Ventilation was controlled throughout theexperiment using a respirator (Mark 8 Respirato~BirdCorp., Palm Springs, Calif.) and adjusted to maintain

arterial partial COZ pressure between 38 and 42 mmHg; inspired Oz was 100%. End tidal halothane con-centration was maintained at an average of 1.3 MAC.A 7F flowdirected balioon-tipped thermodilution

catheter (NOVA Medical Specialities, Indian Milis, N.J.)was inserted percutaneously via the right external jug-ular vein into the pulmonary artery for determinationof cardiac output (CO) (IL 701 Cardiac Output Sys-tem:lnstrumentation bboratories, inc., Lexington,Mass.); for determination of pulmonary artery, pul-monary wedge, and central venous pressure measure-ments (P23Db Statham Biood Pressure TransduceGould, Inc., Oxnard, Caiif.); and for sampiing of mixedvenous puimonary artery blood for pH and blood gasanaiysis.m A dorsal metatarsal attery was cannuiated(Teflon CathetecDeseret Pharmaceutical Co., Sandy,Utah) percutaneously for arterial pressure measure-ments (P23Db Statham Biood Pressure Transducer)and arterial biood sampiing. At the start of each ex-periment, the CO system was calibrated with a con-stant flow pump and the pressure transducers werecalibrated with a Hg manomete~ Catheters placed forpressure measurements were mnnected to an eightchannel electrostatic recorder (Gould ES1000 Re-corderGouid, inc.). A cephalic vein was cannulated(P23Db Statham Blood Pressure Tranducer) percuta-neously for continuous administration of iactatedRingers soiution (5 ml/kg/hr). A lead it surface elec-trocardiogram (ECG) was monitored throughout theexperiment. Body temperature was monitored via thethermodiiution catheter. A heating pad and heatinglamp were used to maintain body temperature.Gastric dilatation-volvulus was created according to

a previously described model.17 Briefly, a mylar balloonwas inserted in the stomach with a stomach tube. Thestomach was surgically rotated about 220 and the an-trum secured to the ieft abdominal wali. The intragas-tric bailoon pressure was raised to and maintained at28 to 32 mm Hg and the abdomen ciosed.Atter 2.5 hours of GDV the abdomen was reopened,

GDV was corrected, and a bolus (90 mi/kg) of lactatedRingers soiution was given over 30 minutes (resus-citation). After resuscitation, anesthesia was main-tained for another 3.0 hours, after which the dogs wereeuthanized with an overdose of pentobarbitai withoutrecovery (Fig. 1).DATA COLLECTIONThe following hemodynamic variables were moni-

tored:q heat rate,q mean arterial blood pressure (MAP),q puimonary artery pressure (PAP),

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Oxygen Variablee in GDV

1 2 0 o 3 0 90 1 5 0 1 8 0 2 4 0 3 0 0 3 6 0FIG.1 Experimentaldesign. Phase1 (PI.): instrumentationperiod;Phase 2 (P2): GDVperiod;Phase3 (Pa):resuscitationperiod;Phase4(Pal):postresusoitationperiod.Singlearrowsdepict bloodsamplingand hemodynamicvariablemeasurement time in minutes.

q pulmonaty wedge pressure (PWP),q central venous pressure (CVP), andq co.Parameters were measured before GDV (baseline =

O min.); duting GDV at 30, 90, and 150 minutes andafter resuscitation at 160,240,300, and 360 minutes (seeFig. 1). Systemic vascular resistance (SVR = [MAP -CVP]/CO), pulmonary vascular resistance (PVR = [PAP- PWP]/CO), and left ventricular minute work (LVMW =CO x MAP x 0.001) were caiculated?laArterial and mixed venous blood samples for meas-

urement of 02 and C02 partial pressures (IL1306 pH/Bloodgas Analyser:lnstrumentation Laboratories, Inc.,Lexington, Mass.) and hemoglobin concentration (To-tal Hemoglobin KK525-A Cyanomethemoglobin Meth-od:Sigma Chemical Co., St. Louis; DB Spectrofotome-tecBeckman Instruments, Inc., Schiller Park, Ill.) werecollected at the same times as the hemodynamic vari-ables (see Fig. 1). Oxygen and C02 partial pressureswere corrected to body temperature. Oxyhemoglobinsaturation, systemic arterial Oz delivety (DOZ) equal toCO x arterial 02 content x 0.01, systemc 02 con-sumption (VOz) equal to arteriovenous Oz content dif-ference x CO x 0.01, and Oz utilization ratio (OJJR)equal to atieriovenous Oz content difference/arterial Ozcontent were calculated.21=At O, 30, 150, 160, and 360 minutes, PSOZ of

stomach, duodenum, jejunum, pancreas, and liver(splanchnic viscera) was measured with an oxygenpolarographic electrode (TOZM 2000: Biomedical Sen-sors, High Wycombe, England) at the same locationsby the same investigator (see Fig. 1). Two recordingsper site were obtained. Before each set of measure-

ments, the sensor was allowed to calibrate in salinesolution at ambient temperature and pressure (20-30min.), and the monitors digital display was manuallyadjusted to the specific room air POZ.4 Special carewas taken to avoid excessive pressure on the sensorand organ in question. No intestinal measurementswere made during peristaltic movements. If the tworecordings per site varied considerably, a second setof recordings was obtained. The average of two PsOZreadings was recorded.DATA ANALYSISAll data were analyzed for temporal trends using a

repeated measures analysis of variance. The presenceor absence of a relationship between the Ps02 valuesof the different splanchnic viscera and certain hemo-dynamic and Oz transport variables was evaluated us-ing a repeated measures analysis of invariance andby determining pooled regression (and correlation) co-efficients, treating PS02 as a time-vatying covariate.=g4In all of the previously mentioned analyses, signifi-cance is claimed whenever p < 0.05.

ResuttsGROSS OBSERVATIONSGastric dilatation-volvulus immediately resulted in

cyanosis of the stomach, duodenum, and pancreas, in-testinal hypermotility, and decreased meeenteric arterialpulsation. Edema and petechd hemorrhage of the pan-creas, congestion of liver and spleen, and gastric serosalhemorrhage were additionally observed after 2.5 hoursof GDV The cyanosis of stomach, duodenum, and

COmlwsd

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Oxygen Verieblee in tlDV

Experimental MirruteeBeeellne GDV Poetreeueoitetiono 30 150 1s0 3s0

%91ue8amexpmmdasrmanksfdarddmiafbn.%@fkarWdhtihOmintiw p .0.01.%gnUkantly dWfemnt fmm O. Inufes, p


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WWn VOf&bkfS in GDV

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Experimental MinutesBaadine GDV Poatreauecitationo 30 1s0 180 240 300 3s0

Hb] 11.80 13.30 12.80 7.60 9.80 10.70 11.20& 1,~ * 1.40= * 1.70 t 1,70CJ * 30@J & 2,70 * 3a(j(j16.50 11.60 8.80 22.10 13.40 12.20 11.30* 3.60 & 2.70d & 3.00= * g.gfjf & 5.10 & 5.3od & 5.44-f3.70 3.s0 4.00 3.90 4.70 4.W 4.40& ().70 * 0.70 * 1.OO & O.go & 2.50 * o.~ * 0.6023.00 34.00 46.00 20.m 33.00 38.00 47.fx)& 6.00 * 7.ood * 11.ood & 8,~ * 15.00 & 13.000 & 17.00082.00 63.00 53.00 74.00 69.00 67.00 5s.00m of Hg) * 20+00 & 18.00d * 19.CKY * 27@ & 21*OO & 21.Ooe * ~.ooe94.70 59.50 47.10 177.00 Ss.lo 74.80 65.70* 13.90 & 11.70d * 14.40= ~ ~,~d$ * 23.3oh * 21.goe & 20,70d

R [mm of 1.05 1.20 0.40 0.78 0.s9 0.s5/(ml/kg/min)] & ;5 * 0413 * ().15 & O.lldf & o.15h ~ 0018 * (),26VMW[mm of 7.S0 3.90 2.50 14.10 6.50 5.30 3.90g/(1./kg/min)] & 2.30 * l.&-y & 1god & 7.@ & 2.soi k 2.70 A 2.70dluea ere expressed as - k standcrd dm.ts fica, n = 10.[Hbl . -bbin concentmtiq ~

. cptemic 02 transpo~ VIZ - systemic 02 cawmpti.m 02UR = 02 utiliza tion ratio; MAP = meen att erial blood preaeurq CO =rdiac ouiput SVR = systemic vcccu lar resis+ancq LVMW - lef tventr icular minute workigni ficcnt iy dNMent fmm O minutee, p


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%lc.pe effect p value Indicaios UM degree of certalnlytih which a change in FzQ? corwponds with a change in eHher CO or ~.%he regression coaff eclent indicates how large a change In CO or CQ would be expected from a given change In P802.

Cardiac output at baseline was 94.7 & 13.9 ml/kgper minute. During GDVi CO dedined to 47.1 & 14.4ml/kg per minute (p -= 0.001). Resuscitation resultedin a rapid Increase of CO to 177 & 52.2 ml/kg perminute (p < 0.001). Additionally, CO had decreasedto 88.1 & 23.3 ml/kg per minute at 240 minutes (p

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Evaluation of systemic and Splanchnic visceral Oxigen Variables in dogs with Surgically induced Gastric-Dilatation-Volvulus (GDV)