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Effect of Intermittent Positive Pressure Ventilation (IPPV) on Acid-Base Balance and Plasma Electrolytes during Isoflurane Anaesthesia in Sulphur-Crested Cockatoos (Cacatua galerita galerita)
並列摘要
The objective of the study was to investigate the effect of Intermittent Positive Pressure Ventilation (IPPV) on acid-base balance and plasma electrolytes during isoflurane anaesthesia in sulphur-crested cockatoos (Cacatua galerita galerita). Anaesthesia was induced in six birds by mask using a T-piece with 3.0% isoflurane. Blood gases, plasma electrolytes, PCV and Total Protein (TP) were monitored for one hour during Spontaneous Ventilation (SV) and IPPV. IPPV was instituted by engaging the pop-off valve (IPPVa) of the circle absorber or by squeezing the breathing bag (IPPVb). Results showed that during SV, pCO_2, pO_2, [HCO_3 ^-], BE, C+CO_2 and PO_4 ^- increased significantly, while [Na^+], [K^+] and [Ca^(2+)] did not change significantly. During IPPV, pCO^2 and pO^2 decreased, while C+CO^2 increased during the initial 30 min. [HCO_3 ^-] increased during IPPVa only in the first 30 min. BE increased only in the first 30 min of IPPV. There was a marginal increase and decrease in PO_4 ^- during SV and IPPV, respectively. [Na^+], [K^+] and [Ca^(2+)] remained stable during both SV and IPPV. Subtle decreases were noted for [Cl^-], TP and PCV during SV. It was concluded that mixed metabolic and respiratory acidosis occurs during SV in isoflurane-anaesthetised cockatoos. Metabolic acidosis that develops during isoflurane anaesthesia in spontaneously ventilating birds is reversible to some extent by IPPV, possibly through a mixed acidosis-alkalosis, respiratory alkalosis and a non-respiratory contribution to alkalosis mechanism. Reversal of Bohr Effect occurs during IPPV in isoflurane-anaesthetised cockatoos. Studies are indicated to understand the causes of decreased oxygen saturation in apparently alkalotic birds.