British journal of anaesthesia
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We have assessed the effects of overinflation on surfactant function and composition in rats undergoing ventilation for 20 min with 100% oxygen at a peak inspiratory pressure of 45 cm H2O, with or without PEEP 10 cm H2O (groups 45/10 and 45/0, respectively). Mean tidal volumes were 48.4 (SEM 0.3) ml kg-1 in group 45/0 and 18.3 (0.1) ml kg-1 in group 45/10. ⋯ Group 45/0 had an increase in non-active to active total phosphorus compared with nonventilated controls (0.90 (0.16) vs 0.30 (0.07)). We conclude that ventilation in healthy rats with peak inspiratory pressures of 45 cm H2O without PEEP for 20 min caused severe impairment of pulmonary surfactant composition and function which can be prevented by the use of PEEP 10 cm H2O.
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Injection of formalin into the hind paw of the rat evokes a biphasic nociceptive behavioural response, which is considered to be an animal model of postoperative pain in humans. The initial response (phase 1) is caused by activation of peripheral nociceptors and is followed by a second phase attributed to ongoing activity in primary afferents and increased sensitivity of dorsal horn neurones. The latter effect is thought to result from glutamate-mediated N-methyl-D-aspartate receptor activation. ⋯ Therefore we contend that supramaximal doses of intrathecal remifentanil sufficient to inhibit phase 1 activity still permitted sufficient glutamate release to allow spinal facilitation. Incomplete suppression of spinal excitatory neurotransmitter release by intrathecal opioids is consistent with spinal wind-up that is triggered during phase 1 and results in phase 2 afferent drive. This might reflect one of the mechanisms underlying post-operative pain.
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Comment Letter Comparative Study
Ondansetron compared with metoclopramide in the treatment of PONV.
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Biography Historical Article Classical Article
The human cardiovascular response to fluothane anaesthesia. 1956.