Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2006
The usefulness of transesophageal echocardiography during intraoperative cardiac arrest in noncardiac surgery.
According to guidelines established by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists, life-threatening hemodynamic disturbances are classified as a category I indication for the intraoperative use of transesophageal echocardiography (TEE). However, the usefulness of TEE during intraoperative cardiac arrest and its impact on patient management have not been rigorously investigated. Using our departmental TEE database, we identified a population of 22 patients who underwent noncardiac surgical procedures and experienced unexpected intraoperative hemodynamic collapse requiring the initiation of Advanced Cardiac Life Support procedures between the time of induction of general anesthesia and the termination of the surgical procedure. ⋯ In 18 patients, TEE guided specific management beyond implementation of Advanced Cardiac Life Support protocols, including the addition of surgical procedures in 12 patients. Fourteen patients survived to leave the operating room, and 7 of these patients were eventually discharged from the hospital. Thus, TEE may provide additional diagnostic information in patients with intraoperative cardiac arrest and may directly guide specific, potentially life-saving therapy.
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Anesthesia and analgesia · Jun 2006
The implications of arterial Po2 oscillations for conventional arterial blood gas analysis.
In a surfactant-depletion model of lung injury, tidal recruitment of atelectasis and changes in shunt fraction lead to large Pao2 oscillations. We investigated the effect of these oscillations on conventional arterial blood gas (ABG) results using different sampling techniques in ventilated rabbits. In each rabbit, 5 different ventilator settings were studied, 2 before saline lavage injury and 3 after lavage injury. ⋯ After saline lavage, when Po2 fluctuations measured by the indwelling arterial Po2 probe confirmed tidal recruitment, Pao2 by ABG was significantly higher at peak (295 +/- 130 mm Hg) compared with trough (74 +/- 15 mm Hg) or mean (125 +/- 75 mm Hg). In early, mild lung injury after saline lavage, Pao2 can vary markedly during the respiratory cycle. When atelectasis is recruited with each breath, interpretation of changes in shunt fraction, based on conventional ABG analysis, should account for potentially large respiratory variations in arterial Po2.
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Anesthesia and analgesia · Jun 2006
Morphine, oxycodone, methadone and its enantiomers in different models of nociception in the rat.
We studied the effects of the commonly used mu-opioid receptor agonists morphine, oxycodone, methadone and the enantiomers of methadone in thermal and mechanical models of acute pain and in the spinal nerve ligation model of neuropathic pain in rats. Subcutaneous administration of morphine, oxycodone, and methadone produced a dose-dependent antinociceptive effect in the tail flick, hotplate, and paw pressure tests. l-methadone, racemic methadone, and oxycodone had a similar dose-dependent antinociceptive effect, whereas the dose-response curve of morphine was shallower. In the spinal nerve ligation model of neuropathic pain, subcutaneous administration of morphine, oxycodone, methadone and l-methadone had antiallodynic effects in tests of mechanical and cold allodynia. l-methadone showed the strongest antiallodynic effect of the tested drugs. d-methadone was inactive in all tests. ⋯ In conclusion, in acute nociception all mu-opioid receptor agonists produced antinociception, with morphine showing the weakest effect. In nerve injury pain, l-methadone showed the greatest antiallodynic potency in both mechanical and cold allodynia compared with the other opioids. Opioids seem to have different profiles in different pain models. l-methadone should be studied for neuropathic pain in humans.
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Anesthesia and analgesia · Jun 2006
Onset time for sevoflurane/nitrous oxide induction in adults is prolonged with increasing age.
Inhaled induction of anesthesia is occasionally used in adults. Using a modified vital capacity sevoflurane/nitrous oxide (N2O) inhaled induction, we evaluated the effect of increasing age on the onset time of anesthesia. Twenty patients, aged 26-65 yr, performed a vital capacity breath followed by regular tidal breathing from an anesthesia circuit primed with sevoflurane 8%/N2O/O2. ⋯ Times to LOER and BIS < or =60, predicted from the regression line, were 3.9 and 2 times longer in a 60-yr-old than in a 30-yr-old patient. The expired fraction of sevoflurane measured at time to LOER and BIS < or =60 decreases with increase in age. We conclude that inhaled induction with sevoflurane/N2O is dramatically prolonged with increased age.
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Anesthesia and analgesia · Jun 2006
The neurotoxic effects of amitriptyline are mediated by apoptosis and are effectively blocked by inhibition of caspase activity.
Oral tricyclic antidepressants, widely used as adjuncts in the treatment of chronic pain, block sodium channels in vitro and nerve conduction in vivo. However, toxicity of amitriptyline has been observed after neural application. We therefore investigated the mechanism and possible prevention of amitriptyline neurotoxicity. ⋯ Co-incubation with z-vad-fmk substantially improved neuronal survival in culture. In conclusion, amitriptyline-induced neurotoxicity is mediated by apoptosis and is attenuated by inhibition of caspase activity, suggesting that inhibition of apoptotic pathways may be efficient at alleviating local anesthetic-induced neurotoxicity. In vivo studies will have to corroborate whether the co-injection of anti-apoptotic drugs with local anesthetics decreases neurotoxic side effects.