Intermittent Hypoxia and the Practice of Anesthesia
Department of Anesthesia, McGill University Health Centre, Montreal, Canada. Anesthesiology
(Impact Factor: 5.88).
05/2009; 110(4):922-7. DOI: 10.1097/ALN.0b013e31819c480a
Intermittent hypoxia, a powerful and unique stimulus, leads to physiologic changes that are distinct from those associated with either single or continuous hypoxic exposure. There is an accumulating body of evidence that the neurocognitive, inflammatory and cardiovascular symptoms that characterize the syndrome of obstructive sleep apnea are linked to the stimulus of intermittent hypoxia. In addition, altered sensitivities to opiates in children with obstructive sleep apnea have been linked to recurrent hypoxia during sleep. Therefore anesthesiologists should have an understanding of this important stimulus.
Available from: Anthony G Doufas
- "Furthermore, both children suffering from OSA  and rats treated during development with chronic intermittent hypoxia  were more sensitive to the respiratory depressant effect of fentanyl. Although the mechanism for this effect of recurrent hypoxia on pain and analgesia systems is vague, in vivo evidence suggests that an up-regulation of μ-opioid receptors might be responsible for the observed increase in the potency of opioids –. "
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ABSTRACT: Obstructive sleep apnea (OSA) is characterized by recurrent nocturnal hypoxia and sleep disruption. Sleep fragmentation caused hyperalgesia in volunteers, while nocturnal hypoxemia enhanced morphine analgesic potency in children with OSA. This evidence directly relates to surgical OSA patients who are at risk for airway compromise due to postoperative use of opioids. Using accepted experimental pain models, we characterized pain processing and opioid analgesia in male volunteers recruited based on their risk for OSA.
Available from: Jennifer Anne Rabbitts
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ABSTRACT: To investigate the effect of altitude on perioperative opioid requirements in otherwise healthy children.
To investigate whether children living and having surgery at high altitude received different doses of fentanyl than those living and having surgery at sea level.
Recent studies in animals (Anesthesiology, 105, 2006 and 715) and children with obstructive sleep apnea (Anesthesiology, 105, 2006 and 665; Anesthesiology 100, 2004 and 806) suggest that analgesic effects of exogenous opioids are enhanced by hypoxia. However, the effects of hypoxia on perioperative narcotic requirements in otherwise healthy children have not been previously reported.
We reviewed retrospectively the opioid requirements of pediatric patients who underwent cleft lip or palate surgery during Smile Network International mission trips to Cusco and Lima, Peru between 2007 and 2009. Patients who had surgery at high altitude were compared to those who had surgery at sea level. All patients received a standardized anesthetic with intravenous fentanyl as the only perioperative opioid.
Hundred and two patients had surgery at 3399 m above sea level (masl) (Cusco) and 169 patients had surgery at 150 masl (Lima). Patients at high altitude had significantly lower baseline oxygen saturations (92 ± 4% vs 98 ± 3%; P < 0.001) and received 40% less opioid (1.2 ± 0.8 vs 2.0 ± 1.4 μg·kg(-1) per h; P < 0.001) compared to patients at sea level.
Opioid administration was reduced in otherwise healthy children with altitude-induced chronic hypoxia when compared to non-hypoxic children undergoing similar operations under similar anesthetic regimens. Whether this difference is due to altitude or altitude-induced hypoxia, requires further study.
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