Rev. Bras. Anestesiol. vol.65 número3

REVISTA

BRASILEIRA

DE

ANESTESIOLOGIA

www.sba.com.br

SCIENTIFIC

ARTICLE

Influence

of

different

body

positions

in

vital

capacity

in

patients

on

postoperative

upper

abdominal

Bruno

Prata

Martinez

,

Joilma

Ribeiro

Silva

,

Vanessa

Salgado

Silva

,

Mansueto

Gomes

Neto

_,

_Luiz

_Alberto

_Forgiarini

_Júnior

a_{HospitalAlianc¸a,Salvador,BA,Brazil}

b_{EscolaBaianadeMedicinaeSaúdePública(EBMSP),Salvador,BA,Brazil}

c_{FaculdadeSocialdaBahia(FSBA),Salvador,BA,Brazil} d_{UniversidadeFederaldaBahia(UFBA),Salvador,BA,Brazil}

e_{CentroUniversitárioMetodista(IPA),PostgraduatePrograminRehabilitationandInclusionandBiosciencesandRehabilitation,}

PortoAlegre,RS,Brazil

f_{LaboratoryofAirwayandLung,HospitaldeClínicasdePortoAlegre,PortoAlegre,RS,Brazil}

Received26March2014;accepted2June2014 Availableonline20February2015

KEYWORDS

Positioningthe patient;

Forcedvitalcapacity; Postoperative complications; Abdominalsurgery

Abstract

Rationale: Thechangesinbodypositioncancausechangesinlungfunction,anditis neces-sarytounderstandthem,especiallyinthepostoperativeupperabdominalsurgery,sincethese patientsaresusceptibletopostoperativepulmonarycomplications.

Objective: Toassessthevitalcapacityinthesupineposition(headat0◦_and45◦_),sittingand standingpositionsinpatientsinthepostoperativeupperabdominalsurgery.

Methods:Across-sectionalstudyconductedbetweenAugust2008andJanuary2009inahospital inSalvador/BA.Theinstrumentusedtomeasurevitalcapacitywasanalogicspirometer,the choiceofthesequenceofpositionsfollowedarandomorderobtainedfromthedrawofthe fourpositions.Secondarydatawerecollectedfromthemedicalrecordsofeachpatient.

Results:The sample consisted of 30 subjects with a mean age of 45.2±11.2 years, BMI 20.2±1.0kg/m2_{.Thepositiononorthostasisshowedhighervaluesofvitalcapacityregarding}

standing (mean change: 0.15±0.03L; p=0.001), the supine to 45 (average difference: 0.32±0.04L;p=0.001)and0◦_{(0.50±0.05L;p=0.001).Therewasapositivetrendbetweenthe} valuesofforcedvitalcapacitysupinetouprightposture(1.68±0.47;1.86±0.48;2.02±0.48 and2.18±0.52L;respectively).

Conclusion: Bodypositionaffectsthevaluesofvitalcapacityinpatientsinthepostoperative upperabdominalsurgery,increasinginpostureswherethechestisvertical.

© 2014SociedadeBrasileirade Anestesiologia.Publishedby ElsevierEditoraLtda.Allrights reserved.

∗_{Correspondingauthor.}

E-mail:[email protected](L.A.ForgiariniJúnior).

http://dx.doi.org/10.1016/j.bjane.2014.06.002

PALAVRAS-CHAVE

Posicionamentodo paciente;

Capacidadevital forc¸ada; Complicac¸ões pós-operatórias; Cirurgiaabdominal

Influênciadediferentesposic¸õescorporaisnacapacidadevitalempacientesno pós-operatórioabdominalsuperior

Resumo

Justificativa:Asalterac¸õesnoposicionamentocorporalpodemocasionarmudanc¸asnafunc¸ão respiratóriaeénecessáriocompreendê-las,principalmentenopós-operatórioabdominal supe-rior,jáqueospacientesestãosuscetíveisacomplicac¸õespulmonarespós-operatórias.

Objetivo:Verificaracapacidadevitalnasposic¸õesdedecúbitodorsal(cabeceiraa0◦ _e45◦_), sentadoeemortostaseempacientesnopós-operatóriodecirurgiaabdominalsuperior.

Métodos: Estudotransversal,feitoentreagostode2008ejaneirode2009,emumhospitalna cidadedeSalvador(BA).Oinstrumentousadoparamensurac¸ãodacapacidadevital(CV)foio

ventilômetroanalógicoeaescolhadasequênciadasposic¸õesseguiuumaordemaleatóriaobtida apartirdesorteiodasquatroposic¸ões.Osdadossecundáriosforamcolhidosnosprontuáriosde cadapaciente.

Resultados: Aamostrafoicompostapor30indivíduoscomidademédiade45,2±11,2anose IMC20,2±1,0kg/m2_{.Aposic¸ãoemortostaseapresentou valoresmaioresdaCVemrelac¸ão}

àsedestrac¸ão(médiadas diferenc¸as: 0,15±0,03litros;p=0,001),ao decúbitodorsal a45◦ (médiadasdiferenc¸as:0,32±0,04litros;p=0,001)e0◦ _{(0,50±0,05litros;p=0,001).Houve} um aumentopositivoentreosvalores deCVFdodecúbitodorsal paraaposturaortostática (1,68±0,47;1,86±0,48;2,02±0,48e2,18±0,52litros;respectivamente).

Conclusão:Aposic¸ãodocorpoafetaosvaloresdaCVempacientesnopós-operatóriodecirurgia abdominalsuperior,comaumentonasposturasemqueotóraxencontra-severticalizado. ©2014SociedadeBrasileiradeAnestesiologia.PublicadoporElsevierEditoraLtda.Todosos direitosreservados.

Introduction

Upper abdominal surgical procedures account for a large number of postoperative pulmonary complications (PPC) because these procedures directly interfere with lung mechanics and tend to induce restrictive ventilatory dis-orders, as well as reflex inhibition of phrenic nerve and consequentdiaphragmaticdysfunction.1---3_Duringearly

post-operative period, patients may present hypoventilation

relatedtothe anestheticprocess,aswellaslimiting ven-tilatorychangesduetopaininsurgicalsite.4

TheprevalencerateofPPCinupperabdominalsurgery

varies between 17% and 88%.5 _{These changes are more}

marked in laparotomy procedures, but are also seen in

laparoscopicsurgeries.1

Pulmonary functiontests playan importantrole inthe

assessment,diagnosis,quantificationoftheventilatory dis-orders intensity, and treatment course.6 _{The forced vital}

capacity(FVC)isapulmonaryfunctionmeasureoftenused

forthispurposeandisdefinedasthemaximumvolumeofair

exhaledfromaftermaximuminspiration.6,7_DecreasedFVC

isafairlyobviousabnormalityinpatients withrespiratory muscleweaknessorchangesinlungmechanicsthatoverload

these muscles.7,8 _{These decreases after upper abdominal}

surgery rangefrom 20% to30% of the preoperative value

andmayachievemoresignificantvaluesupto50%.7,9---11

Changeinbodypositioningandtheconsequentchangeof

gravityeffect,amongotherfactors,causechangein respi-ratoryfunction atdifferentintensities.12 _{Thus,knowledge}

ofthe physiological effectsof different bodypositions on pulmonaryfunctionisessentialtoguidethephysical ther-apyprocedures,includingspirometryinclinicalpractice,so

that itsvalues are comparablebetween different periods

andpatients.13_{Therefore,theobjectiveofthisstudywasto}

investigatethefunctionalvitalcapacityinthesupine(head at0◦_and45◦_{),sittingonthebedwithhangingdownlegs,and}

uprightpositionsinpatientsafterupperabdominalsurgery.

Method

Cross-sectional study conducted in the wards of Hospital

Santo Antônio ---Obras SociaisIrmãDulce, Salvador, Bahia State,acityreferenceinabdominalsurgery.

Patientsagedover18years,onthesecondpostoperative

day of upper abdominal surgery, with history of previous

functional independence and medical release and

stand-up were included. Exclusion criteria were patients with

irreversiblepainwithpainkillers,neurologicaland/or

cogni-tiveimpairmentthatpreventedtheFVCmeasurementand

adecreaseinbloodpressuregreaterthan20%frombaseline duringpositionchange.

The study was approved by the Research Ethics

Com-mitteeofthehospital,protocolnumber40/06.Allpatients

signedaninformedconsentform(ICF).

DatacollectionwasconductedfromAugust2008to

Jan-uary 2009. Forced vital capacity (FVC) measurement was

defined according to the 2002 guidelines for pulmonary

function tests.6 _{The toll used for this measurement was}

the analog spirometer (Ferraris --- Mark 8 Respirometer

Wright,Louisville,CO,USA)coupledtoasiliconfacemask.

The sequence of positions was randomized by blocks of

envelopes.Subsequently,subjectswereplacedinselected

Table 1 Demographic data of patients included in the study.

Mean±SD Percentage(n)

Age(years) 45.2±11.2

BMI(kgm−2_{) 20.2±1.0}

Tipo

ELcholecystectomy 16.7(5)

VLCcholecystectomy 50.0(15)

Nephrectomy 10.0(3)

Gastrectomy 3.3(1)

Pancreaticoduodenectomy 16.7(5)

Cystectomy 3.3(1)

EL,exploratorylaparoscopic;VLC,videolaparoscopic.

lung capacity (TLC) followed by a maximal expiration to residualvolume(RV). The vitalcapacity valueadopted in eachpositionwasthehighestvalueamongthree measure-mentswithlessthan10%differencebetweenthem.Thefour positionsusedinthepresentstudyweresupineat0◦_,supine

at45◦_{sittingwithhangingdownlegs,andupright.All}

mea-surementswereperformedbythesameinvestigator.Clinical datawereobtainedthroughmedicalrecordsofeachpatient. Meanandstandarddeviationwereusedtorepresentthe FVCvaluesobtainedinbodypositionsanalyzed.Analysisof Variance(ANOVA)withposthocBonferronitestwasusedto comparethemeanvaluesofFVCbetweeneachbody posi-tion.AllanalyseswereperformedusingSPSSversion14.0.

Results

The population consisted of 30 subjects, mean age of 45.2±11.2 years,BMIof 20.2±1.0kgm−2_{,predominantly}

female(76.7%).Table1showsthedemographic character-isticsandoperationsperformed.ValuesofFVCindifferent positionsareshowninTable2.Thehighest valueobtained

was for the upright position (FVC 2.18±0.52; 95% CI

1.99---2.37).

Compared withtheother threepositions,upright

posi-tionshowedsignificantlyhighervaluesinrelationtositting (meanofdifferences:0.15±0.03;p=0.001),supineat45◦

(meanofdifferences:0.32±0.04;p=0.001),andsupineat 0◦_{(0.50±0.05;p=0.001).Therewerealsosignificant}

differ-encesbetweenthesittingpositionwithhangingdownlegs

andsupinepositionat45◦_{(meanofdifferences:0.17±0.04;}

Table2 Evaluation oftheforced vitalcapacity (FVC)in liters (L)indifferent body positions,with 95%confidence interval(95%CI).

Bodyposition Mean Standard

deviation

Confidence interval(95%CI)

Supine(0◦_{) 1.68 0.47 1.51---1.85}

Supine(45◦_{) 1.86 0.48 1.68---2.04}

Sitting 2.02 0.48 1.84---2.21

Upright 2.18 0.52 1.99---2.37

Dataare expressedasmeanandstandarddeviationofforced vital capacity (FVC) in liters (L) in different body positions (n=30).

2.20

2.10

2.00

1.90

1.80

1.70

1.60

Forced vital capacity (liters)

1 2 3 4

Body positions: 1) dorsal decubitus at 0°; 2) dorsal decubitus at 45°; 3) sitting with hanging legs; 4) upright.

Figure1 MeanVC(L)indifferentpositions:(1)dorsal decu-bitusat0◦_{;(2)dorsaldecubitusat45}◦_{;(3)sittingwithhanging} legs;and(4)upright.

p=0.001) and at 0◦ _{(mean of difference: 0. 34±0.04;} p=0.001),aswell asbetween supineat45◦ _and0◦ _(mean

difference:0.17±0.04;p=0.001)(Fig.1).Therewasa

pos-itivetrendbetween supineFVCvalues touprightposition

(Table3).

Discussion

The present study found that FVC increases progressively

betweensupineat0◦_{anduprightpositionsinpatientsafter}

upperabdominalsurgery.Thisisthefirststudytoevaluate

respiratory mechanics throughVC in this type of surgical

patients,whichissomewhatrelevant,astheuppersurgeries

predisposetocomplicationsandpositioningmayminimize

someventilatorychanges.

Compared to other positions evaluated in this study,

therewasagreaterdecreaseinFVCinsupinepositionat0◦_,

afindingthatisinagreementwiththatofotherstudies.14,15

Thisdecreasemaybeattributedtodecreaseddynamiclung

compliance and increased resistance to pulmonary blood

flow, resulting from reduced FRC in this position.15,16 _In

supineposition,anatomicalchangesoccurinthepharynx,

suchasthereductionofitsdiameter,whichincreasesthe

upperairwayresistance.Thecephalicdisplacementofthe

diaphragm due to increased abdominalpressure, and the

increasedintrathoracicbloodvolume,arealsofactorsthat resultinreducedlungvolumeatrestandjustifyanincrease inairwayresistanceinthisbodyposition.15

In the present study, the sitting position showed an

increaseof20.2%inFVCcomparedtosupineposition.This

finding corroborates other studies that showed increased

FVCin this positionranging from4.6% to 20% in patients

undergoingabdominalprocedure.14---17 _{This findingmaybe}

Table3 Comparisonofforcedvitalcapacity(FVC)inliterswithmeandifferencesbetweendifferentbodypositions(n=30).

Selectedbodyposition Comparedbodyposition Mean Standarddeviation p

Supine(0◦_{) 45}◦ _−0.17a _{0.04 0.001}

Sitting −0.34a _{0.04 0.001}

Upright −0.50a _{0.05 0.001}

Supine(45◦_{) 0}◦ _{0.17 0.04 0.001}

Sitting −0.17 0.04 0.001

Upright −0.32 0.04 0.001

Sittingwith hangingdownlegs

0◦ _{0.34 0.04 0.001}

45◦ _{0.17 0.04 0.001}

Upright −0.15 0.03 0.001

Upright 0◦ _{0.50 0.05 0.001}

45◦ _{0.32 0.04 0.001}

Sitting 0.15 0.03 0.001

a_{Significantdifference(p<0.05).}

and overcomes the tendency to airway closure related

tochanges in lung complianceand lower pressure of the

abdominalorgansinrelationtothediaphragm.18

TheuprightpositionshowedthehighestincreasesinFVC. Asimilarfindingwasreportedbyotherauthorswhosuggest thattheuprightpositionprovidesgreatermechanical

advan-tagetotherespiratorymuscles, asabdominalcontentsdo

notinterferewithdiaphragmdisplacementand,thus,

gen-erateshigher ventilation pressures.19,20 _{In contrast,Costa}

etal.andDomingos-Benícioetal.foundnostatistically sig-nificantdifferenceinFVCbetween thesittingandupright

positions, but these studies were conducted with a

non-surgical, healthy, and young population.17,21 _{According to}

Pereira et al., FVC in adults and elderly is higher in the upright position (1---2%) and lower in the supine position

(7---8%) compared to the sitting position, which does not

occurinyoungerpeople.6

The main explanationfactorfor the increasein FVCin

amorevertical chestpositionis thepossible reductionin transthoracic pressure, as even in the 45◦ _{position there}

isless compressiveeffectoftheabdominalwall, whichis greaterinthe0◦ _{horizontalposition.Valenzaetal.}

demon-stratetheimpactof increasedpleural pressureunderthe

diaphragm,astheforceexertedontheTrendelenburg posi-tionwashighercomparedwiththesittingposition,16_which

was also shown in a study by Behrakis et al. regarding

compliance.15

AnotherexplanationforFVCreductioninsupineposition at0◦_{maybeduetothereductioninalveolararea,andnot}

onlybytheincreasedfrequencyofatelectasis,asreported byPankowetal.22_{However,inthepresentstudythis}

find-ingwasnotevident sincethereducedFVC maybedue to

inhibitionofphrenicnervereflexandnotnecessarilytothe

increased respiratory system elastance by the abdominal

surgicaltrauma.

The upper abdominal surgery induces a

diaphrag-matic dysfunction lasting for about a week and may

be a major cause of postoperative pulmonary restrictive

pattern.2_{Reduceddiaphragmaticfunctionmaybe}

responsi-bleforatelectasis,reducedvitalcapacity,andhypoxemia.3

Althoughanesthesiaandpainmayberesponsiblefor respira-torymuscledysfunction,studiessupportthehypothesisthat aninhibitoryreflexduetotheabdominalcavity manipula-tionisthemainmechanism.1---3,23---25_{Therefore,thelowFVC}

valuesseeninpatientsinthepresentstudyindifferent

pos-itions maybedue todiaphragmatic dysfunctionmediated

byreflexmechanismofafferentphrenicnerveinhibition.

Thus, knowledge of body positions that favor lung

function can be used as a therapeutic measure, aiming

at improving lung volume, oxygenation, and respiratory

mechanicsandminimizingdisturbancesproducedbymajor

surgical procedures,withreducedincidenceofatelectasis andpreventionofpulmonarycomplications.16,26---29

Thisstudyhassomelimitations,suchasthelackof intra-abdominalpressure(IAP)measurement,asitselevationmay bepresentafterabdominalsurgeryandgeneratechangesin

spirometricdata.However,IAPmeasurementisaninvasive

procedure requiring specializedprofessional,which would

hinderthestudyconduction.Anotherpossiblelimitationis

the use ofa facemask asa measuringtool insteadof the

nozzle.AccordingtoFioreetal.,30 _{VCevaluationsmaybe}

done using a facemask without interfering in the results

and become accessible topatients whohave difficulty in

performingtheevaluation,aslippressurebecomes

unnec-essary.

Conclusion

Body position affects VC values in patients after upper

abdominalsurgery,withanincreaseinpostureswherethe

chestismoreverticallypositioned.Themostfavored respi-ratoryfunction is inthe uprightposition, followedby the sittingposition,comparedwiththesupinepositionat0◦_and

45◦_.

Conflicts

of

interest

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