Diferentes frações inspiradas de oxigênio associado ao ar comprimido ou óxido nitroso, em leitões anestesiados com propofol e mantidos sob ventilação controlada e peep
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Data
2017-12-18
Autores
Biteli, Eliselle Gouveia de Faria [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Compararam-se os efeitos de diferentes frações inspiradas de oxigênio (FiO2) associado ao óxido nitroso (N2O) ou ao ar comprimido sobre a hematose, parâmetros cardiorrespiratórios, intracranianos e o índice biespectral (BIS), em leitões mantidos em ventilação espontânea ou controlada a pressão, associada ou não à PEEP (5 cmH2O). Foram utilizados 48 leitões, distribuídos em 6 grupos, submetidos à 10, 30 e 50% de ar comprimido (GA10, GA30 e GA50) ou N2O (GN10, GN30 e GN50), associadas às FiO2 de 0,9, 0,7 e 0,5, respectivamente. O GA30 mostrou maior proximidade do intervalo fisiológico da pressão parcial de oxigênio no sangue arterial. A PEEP não foi eficaz na pressão parcial de dióxido de carbono no sangue arterial, independente da FiO2, quando se utilizou o N2O. O pH, déficit base e bicarbonato no sangue arterial foram influenciados pela FiO2 e N2O. As alterações do volume corrente e volume minuto parecem correlacionadas à introdução da ventilação mecânica (VM) e PEEP. Na diferença alvéolo-arterial de oxigênio, a PEEP influenciou negativamente o GA30 e GN30 e não foi adequada para manutenção do shunt pulmonar. Já a pressão média da artéria pulmonar e pressão média capilar pulmonar apresentaram acréscimos após introdução da PEEP. A associação da PEEP com N2O (50%) ou ar comprimido (50%) parece ser a receita para desempenho inferior da variação de pressão de pulso. Para a pressão intracraniana, apenas o GN30 apresentou valor menor ao se instituir a VM quando comparado com o momento em que houve início do auxílio com a PEEP. Concluiu-se que, nenhuma concentração de N2O é segura para a manutenção dos parâmetros hemogasométricos. A VM e a PEEP não são eficientes para manutenção das variáveis respiratórias. A PEEP promove piora no desempenho de parâmetros cardiovasculares e intracranianos. Maiores taxas de oferta de N2O (50%) reduzem o BIS em suínos.
The effects of different fractions of inspired oxygen (FiO2) associated with compressed air or nitrous oxide (N2O) on lung oxygenation, cardiorespiratory parameters, intracranial parameters and the bispectral index (BIS) were compared in piglets maintained under spontaneous or controlled ventilation, with or without PEEP (5 cmH2O). Forty-eight piglets, distributed in six groups, were submitted to 10, 30 and 50% of compressed air (GA10, GA30 and GA50) or N2O (GN10, GN30 and GN50), associated with FiO2 of 0.9, 0.7 and 0.5, respectively. GA30 showed greater proximity to the physiological range of partial oxygen pressure in the arterial blood. When N2O was used, PEEP was ineffective in maintaining partial carbon dioxide pressure in the arterial blood, independent of FiO2. Arterial blood pH, base deficit and bicarbonate were influenced by FiO2 and N2O. Changes in tidal and minute volumes seem to correlate with the introduction of mechanical ventilation (MV) and PEEP. The difference in alveolar-arterial oxygen under PEEP negatively influenced GA30 and GN30 and was inadequate for pulmonary shunt maintenance. Mean pulmonary artery pressure and mean capillary pulmonary pressure increased following the initiation of PEEP. The association of PEEP with N2O (50%) or compressed air (50%) seems to result in lower performance of pulse pressure variation. Regarding intracranial pressure, only GN30 presented a lower value when MV was established compared with the time point when PEEP was initiated. In conclusion, no concentration of N2O is safe for maintaining blood gas parameters. MV and PEEP are inefficient in the maintenance of respiratory variables. PEEP promotes deterioration in the performance of cardiovascular and intracranial parameters. Higher N2O supply rates (50%) reduce BIS in pigs.
The effects of different fractions of inspired oxygen (FiO2) associated with compressed air or nitrous oxide (N2O) on lung oxygenation, cardiorespiratory parameters, intracranial parameters and the bispectral index (BIS) were compared in piglets maintained under spontaneous or controlled ventilation, with or without PEEP (5 cmH2O). Forty-eight piglets, distributed in six groups, were submitted to 10, 30 and 50% of compressed air (GA10, GA30 and GA50) or N2O (GN10, GN30 and GN50), associated with FiO2 of 0.9, 0.7 and 0.5, respectively. GA30 showed greater proximity to the physiological range of partial oxygen pressure in the arterial blood. When N2O was used, PEEP was ineffective in maintaining partial carbon dioxide pressure in the arterial blood, independent of FiO2. Arterial blood pH, base deficit and bicarbonate were influenced by FiO2 and N2O. Changes in tidal and minute volumes seem to correlate with the introduction of mechanical ventilation (MV) and PEEP. The difference in alveolar-arterial oxygen under PEEP negatively influenced GA30 and GN30 and was inadequate for pulmonary shunt maintenance. Mean pulmonary artery pressure and mean capillary pulmonary pressure increased following the initiation of PEEP. The association of PEEP with N2O (50%) or compressed air (50%) seems to result in lower performance of pulse pressure variation. Regarding intracranial pressure, only GN30 presented a lower value when MV was established compared with the time point when PEEP was initiated. In conclusion, no concentration of N2O is safe for maintaining blood gas parameters. MV and PEEP are inefficient in the maintenance of respiratory variables. PEEP promotes deterioration in the performance of cardiovascular and intracranial parameters. Higher N2O supply rates (50%) reduce BIS in pigs.
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Palavras-chave
Alquilfenol, Atelectasia, Colapso alveolar, Shunt, Suínos