Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942004000400010
Brazilian Journal of Anesthesiology
Scientific Article

P ET CO2 e SpO2 permitem ajuste ventilatório adequado em pacientes obesos mórbidos

P ET CO2 and SpO2 allow adequate ventilatory adjustment in morbidly obese patients

Fábio Ely Martins Benseñor; José Otávio Costa Auler Júnior

http://dx.doi.org/10.1590/S0034-70942004000400010 Braz J Anesthesiol, vol.54, n4, p.542-552, 2004
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Resumo

JUSTIFICATIVA E OBJETIVOS: Apesar das diversas propostas ventilatórias para anestesia em pacientes obesos mórbidos, um consenso não foi estabelecido. Este estudo avaliou o ajuste ventilatório nestes pacientes durante anestesia baseado na oximetria e capnografia. MÉTODO: O consentimento prévio foi obtido da Comissão de Ética e dos pacientes. Excluíram-se tabagistas e portadores de doença cardíaca ou pulmonar. Foram estudados 11 pacientes com índice de massa corpórea (IMC) de 59,2 ± 8,3 submetidos à gastroplastia sob anestesia geral (Grupo O). Oito não-obesos (IMC 20,2 ± 3,9) submetidos à gastrectomia formaram o grupo controle (NO). Ajustou-se a ventilação visando dióxido de carbono expiratório final (P ET CO2) menor que 40 mmHg e saturação periférica de oxigênio (SpO2) maior que 95%. Não se utilizou PEEP. Através de monitor respiratório CO2SMO Plus, mediu-se espaços mortos fisiológico, alveolar e de vias aéreas (VD phy, VD alv e VD aw) e o volume corrente alveolar (VT alv). Amostras de sangue arterial e venoso central permitiram calcular PaO2/FIO2 e VD phy/VT. Os dados foram comparados e analisados por ANOVA (p < 0,05). RESULTADOS: Volumes corrente foram de 4,2 ± 0,4 ml.kg-1 no Grupo O e 7,9 ± 2,3 ml.kg-1 no Grupo NO para o peso medido, e de 11,5 ± 1,8 no Grupo O e 6,6 ± 1,1 ml.kg-1 no Grupo NO para o peso ideal. A PaO2 mostrou-se menor e o VT alveolar mostrou-se maior nos obesos (p < 0,008 e 0,0001, respectivamente). Não foi encontrada diferença em PaCO2, VD phy, VD alv ou VD aw. CONCLUSÕES: A SpO2 e a P ET CO2 parecem garantir ventilação adequada, a qual pode ser obtida em pacientes com obesidade mórbida com volumes corrente ajustados ao peso ideal.

Palavras-chave

DOENÇAS, VENTILAÇÃO

Abstract

BACKGROUND AND OBJECTIVES: Ventilation strategies for anesthesia in morbidly obese patients have been investigated, but an agreement has not been achieved yet. This study aimed at clinically evaluating ventilation adjustments based on oximetry and capnography readings in these patients during anesthesia. METHODS: Consent was obtained from the Institutional Ethics Committee and from patients. Smokers and respiratory or cardiac disease patients were excluded. Eleven patients with Body Mass Index (BMI) of 59.2 ± 8.3 undergoing gastroplasty under general anesthesia were studied (Group O), with a control group (NO) composed of 8 non-obese patients (BMI 20.2 ± 3.9) submitted to gastrectomy. Ventilator was adjusted to keep P ET CO2 below 40 mmHg and SpO2 above 95%. PEEP was not used. Through a CO2SMO Plus respiratory monitor, airway, alveolar and physiologic dead spaces (respectively VD aw, VD phy and VD alv), as well as alveolar tidal volume (TV alv) were measured. Arterial and central venous blood samples were used to calculate PaO2/FIO2 and VD phy/TV relationships. Data were compared and evaluated by ANOVA (p < 0.05). RESULTS: Tidal volume was 4.2 ± 0.4 mL.kg-1 in Group O and 7.9 ± 2.3 mL.kg-1 in Group NO for measured weight, and 11.5 ± 1.8 mL.kg-1 in Group O and 6.6 ± 1.1 mL.kg-1 in Group NO for ideal weight. PaO2 was lower and TV alv was higher in Group O (p < 0.008 and 0.0001, respectively). No difference was found in PaCO2, VD phy, VD alv and VD aw. CONCLUSIONS: SpO2 and P ET CO2 seem to assure adequate ventilation, which can be achieved in morbidly obese patients with tidal volumes adjusted to ideal weight.

Keywords

DISEASES, VENTILATION

References

Halpern A. A epidemia da obesidade. Arq Bras Endocrinol Metab. 1999;43:175-176.

Monteiro CA, Conde WL. A tendência secular da obesidade segundo estratos sociais: Nordeste e Sudeste do Brasil, 1975-1989-1997. Arq Bras Endocrinol Metab. 1999;43:186-194.

Martins IS, Velásquez-Melendez G, Cervato AM. Estado nutricional de grupamentos sociais da área metropolitana de São Paulo, Brasil. Cad Saúde Publica. 1999;15:71-78.

Øberg B, Poulsen TD. Obesity: an anaesthetic challenge. Acta Anaesthesiol Scand. 1996;40:191-200.

Shenkman Z, Shir Y, Brodsky JB. Perioperative management of the obese patient. Br J Anaesth. 1993;70:349-359.

Rosenbaum M, Leibel RL, Hirsch J. Obesity. N Engl J Med. 1997;337:396-407.

Waaler HT. Hazard of obesity: the Norwegian experience. Acta Med Scand. 1988;723(^sSuppl):17-21.

Bardoczky GI, Yernault JC, Houben JJ. Large tidal volume ventilation does not improve oxygenation in morbidly obese patients during anaesthesia. Anesth Analg. 1995;81:385-388.

Buckley FP. Anaesthesia for the morbidly obese patient. Can J Anaesth. 1994;41(R94-R100).

Auler Jr JO, Miyoshi E, Fernandes CR. The effects of abdominal opening on respiratory mechanics during general anesthesia in normal and morbidly obese patients: a comparative study. . .

Hedenstierna G, Santesson J. Breathing mechanics, dead space and gas exchange in the extremely obese, breathing spontaneously and during anaesthesia with intermittent positive pressure ventilation. Acta Anaesthesiol Scand. 1976;20:248-254.

Kufel TJ, Grant BJB. Arterial Blood-Gas Monitoring: Respiratory Assessment. Principles and Practice of Intensive Care Medicine. 1998:197-215.

Pelosi P, Croci M, Ravagnan I. The effects of body mass on lung volumes, respiratory mechanics, and gas exchange during general anaesthesia. Anesth Analg. 1998;87:654-660.

Hedenstierna G, Strandberg Å, Brismar B. Functional residual capacity, thoracoabdominal dimensions, and central blood volume during general anaesthesia with muscle paralysis and mechanical ventilation. Anesthesiology. 1985;62:247-254.

Pelosi P, Ravagnan I, Giurati G. Positive end-expiratory pressure improves respiratory function in obese but not in normal subjects during anaesthesia and paralysis. Anesthesiology. 1999;91:1221-1231.

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