Anesthesia and analgesia
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Anesthesia and analgesia · May 2004
Case ReportsWater intoxication and symptomatic hyponatremia after outpatient surgery.
Severe hyponatremia is associated with a mortality rate of more than 50%, primarily from cerebral edema and central nervous system dysfunction. Water intoxication is an unusual but potentially lethal cause of perioperative hyponatremia. We report a patient with severe postoperative hyponatremia resulting from excessive perioperative water consumption. Anesthesiologists should maintain an index of suspicion for hyponatremia from water intoxication in patients with neurologic symptoms during the perioperative period. Routine preoperative instructions regarding maximum perioperative water intake and inquiry into any concurrent alternative medical therapies may help to avoid this preventable complication. ⋯ Water intoxication is an unusual but potentially lethal cause of perioperative hyponatremia. We report a patient with severe postoperative hyponatremia resulting from excess perioperative water consumption.
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Anesthesia and analgesia · May 2004
Case ReportsTransient vascular insufficiency after axillary brachial plexus block in a child.
Axillary block is used in children for procedures on the hand and forearm. We report on a child with an amputation of the thumb in whom an axillary block was given, after which the limb became pale and pulseless. The pulses returned spontaneously in 15 min. The awareness of this possibility and chances of spontaneous recovery should be considered. ⋯ Transient vascular insufficiency of the upper limb may happen as a rare complication after axillary block. Knowledge of this complication can help the anesthesiologist in the management of this problem.
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Anesthesia and analgesia · May 2004
The relationship between bispectral index and electroencephalographic parameters during isoflurane anesthesia.
Bispectral index (BIS) integrates various electroencephalographic (EEG) parameters into a single variable. However, the exact algorithm used to synthesize the parameters to BIS values is not known. The relationship between BIS and EEG parameters was evaluated during nitrous oxide/isoflurane anesthesia. Twenty patients scheduled for elective ophthalmic surgery were enrolled in the study. After EEG recording with a BIS monitor (A-1050) was begun, general anesthesia was induced and maintained with 0.5%-2% isoflurane and 66% nitrous oxide. Using software we developed, we continuously recorded BIS, spectral edge frequency 95% (SEF95), and EEG parameters such as relative beta ratio (BetaRatio), relative synchrony of fast and slow wave (SynchFastSlow), and burst suppression ratio. BetaRatio was linearly correlated with BIS (r = 0.90; P < 0.01; n = 253) at BIS more than 60. At a BIS range of 30 to 80, SynchFastSlow (r = 0.60; P < 0.01; n = 3314) and SEF95 (r = 0.75; P < 0.01; n = 3339) were linearly correlated with BIS. The correlation between BIS and SEF95 was significantly better than the correlation between BIS and SynchFastSlow (P < 0.01). At BIS less than 30, the burst suppression ratio was inversely linearly correlated with BIS (r = 0.76; P < 0.01; n = 65). At BIS less than 80, burst-compensated SEF95 was linearly correlated with BIS (r = 0.78; P < 0.01; n = 3404). In the range of BIS from 60 to 100, BIS can be calculated from BetaRatio. At surgical levels of anesthesia, BIS and SynchFastSlow (a parameter derived from bispectral analysis) or burst-compensated SEF95 (derived from power spectral analysis) are well correlated. However, our results show that SynchFastSlow has no advantage over SEF95 in calculation of BIS. ⋯ The relationship between bispectral index (BIS) and electroencephalographic parameters was evaluated during nitrous oxide/isoflurane anesthesia. At surgical levels of anesthesia, BIS and the relative synchrony of fast and slow wave (a parameter derived from bispectral analysis) or burst-compensated spectral edge frequency 95% (a parameter derived from power spectral analysis) are well correlated.