Anesthesiology
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This controversy-starting retrospective study reported a 30% reduction in 3 year recurrence-free survival after undergoing mastectomy for primary breast cancer in patients who received a traditional general anaesthetic with morphine analgesia, compared with those receiving a regional (paravertebral) technique.
Although plausible biological mechanisms have been suggested and even demonstrated in vitro, the huge treatment effect is yet to be replicated in better quality retrospective or prospective trials.
Evidence to date does not (yet) support this trial’s findings.
"An extraordinary claim requires extraordinary proof." – Marcello Truzzi
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Randomized Controlled Trial
Recurrent hypoxemia in children is associated with increased analgesic sensitivity to opiates.
Postsurgical administration of opiates in patients with obstructive sleep apnea (OSA) has recently been linked to an increased risk for respiratory complications. The authors have attributed this association to an effect of recurrent oxygen desaturation accompanying OSA on endogenous opioid mechanisms that, in turn, alter responsiveness to subsequent administration of exogenous opiates. In a retrospective study, the authors have shown that oxygen desaturation and young age in children with OSA are correlated with a reduced opiate requirement for postoperative analgesia. ⋯ Previous recurrent hypoxemia in OSA is associated with increased analgesic sensitivity to subsequent morphine administration. Therefore, opiate dosing in children with OSA must take into account a history of recurrent hypoxemia.
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Anesthetic endpoints of unconsciousness and immobility result from agent effects on both brain and spinal cord that are difficult to separate during systemic administration. To investigate cerebral mechanism of anesthetic-induced unconsciousness, the authors studied behavioral and electrophysiologic effects of four anesthetics infused intracerebroventricularly to conscious rats. The authors aimed to produce progressively increasing anesthetic depths, indicated by electro-encephalographic synchronization and behavioral change. ⋯ Alpha and beta power increase may reflect sedative component of anesthesia. Simultaneous delta, alpha, and beta power increase may correlate with loss of consciousness. Theta and delta power increase may reflect surgical anesthesia. Opioid-induced gamma power decrease may reflect suppression of pain perception. Pentobarbital-, fentanyl-, and midazolam-induced immobility to noxious stimulation may be mediated supraspinally.