Anesthesiology
-
Paraplegia is a known complication after surgery on the descending thoracic aorta. Thoracic aortic cross-clamping causes an increase in proximal aortic and cerebrospinal fluid pressures. Sodium nitroprusside, though effectively decreasing proximal aortic pressure, has been implicated in worsening the incidence of paraplegia by further increasing cerebrospinal fluid pressure and decreasing distal blood pressure, thereby reducing spinal cord perfusion pressure. Intravenous administration of magnesium sulfate has been shown to offer some spinal cord protection when used with mild hypothermia. This study investigated the effect of intrathecal magnesium on the prevention of paraplegia when sodium nitroprusside is used to control proximal hypertension during thoracic aortic cross-clamping in a dog model of spinal cord ischemia. ⋯ Intrathecal magnesium can prevent spinal cord injury despite markedly negative spinal cord perfusion pressure during thoracic aortic cross-clamping in a canine model of spinal cord ischemia.
-
Comment Letter Comparative Study
Sympathetically maintained pain and the use of regional anesthesia.
-
Randomized Controlled Trial Clinical Trial
Fentanyl, esmolol, and clonidine blunt the transient cardiovascular stimulation induced by desflurane in humans.
A rapid increase in the end-tidal concentration of desflurane to greater than 1 MAC transiently increases heart rate, arterial blood pressure, and circulating epinephrine and vasopressin concentrations. We hypothesized that drugs that block sympathetic activity or decrease sympathetic outflow (an opioid, a beta-adrenergic antagonist, and an alpha 2-adrenergic agonist) would blunt these responses. ⋯ Fentanyl, esmolol, and clonidine blunt the transient cardiovascular response to a rapid increase in desflurane concentration. Fentanyl may be the most clinically useful of these drugs because it blunts the increase in heart rate and blood pressure, has minimal cardiovascular depressant effects, and imposes little postanesthetic sedation.
-
Randomized Controlled Trial Clinical Trial
Clonidine and lidocaine inhibition of isoflurane-induced tachycardia in humans.
A rapid increase in isoflurane concentration can induce tachycardia and hypertension and increase plasma catecholamine concentrations. To investigate a possible mechanism, we measured hemodynamic responses to isoflurane administered via mask; we also administered clonidine for premedication, lidocaine topically to the nasal mucosa, or lidocaine intravenously to evaluate the effect of these drugs on the hemodynamic responses. ⋯ Stepwise increases in isoflurane concentration elicited hypertension and tachycardia as well as increments in plasma catecholamine concentrations during mask anesthesia. Nasal administration of lidocaine and clonidine premedication significantly blunted the circulatory responses to isoflurane. Intravenous lidocaine did not significantly weaken the responses to changes in isoflurane concentration.
-
Comparative Study
Alterations in temporal patterns of heart rate variability after coronary artery bypass graft surgery.
Preliminary studies have indicated that autonomic nervous system dysfunction may be present in patients after cardiac surgery. The purpose of this study was to evaluate cardiac autonomic nervous system function, as assessed by analysis of heart rate variability (HRV), in adult patients undergoing uncomplicated coronary artery bypass graft surgery. ⋯ HRV is reduced after uncomplicated coronary artery bypass graft surgery. Although we cannot exclude the effects of uncontrolled variables in this reduction of postoperative HRV, the observed changes in HRV did not appear to result from general anesthesia, perioperative stress responses, and other factors associated with the early postoperative period. These data are consistent with the supposition that cardiac autonomic nervous system function is impaired after cardiac surgery.