Anesthesia and analgesia
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Anesthesia and analgesia · May 2005
Randomized Controlled Trial Clinical TrialChanges in the bispectral index during intraabdominal irrigation in patients anesthetized with nitrous oxide and sevoflurane.
Surgical stimulation typically results in an activation of electroencephalographic activity. In some instances, painful stimulation in the presence of inadequate anesthesia results in a suppression of the electroencephalogram. This phenomenon has been referred to as a "paradoxical arousal." In our daily practice, we have noted a marked decrease in the bispectral index (BIS) with large delta waves during abdominal surgery when the abdominal cavity was irrigated with normal saline. ⋯ These data show that the stimulation occurring during intraabdominal irrigation might cause a paradoxical arousal response, as evidenced by a decrease in processed electroencephalographic parameters. Pretreatment with fentanyl suppressed these changes. Anesthesiologists should be aware of this paradoxical arousal response to avoid an inappropriate decrease in the anesthetic concentration in such situations.
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Anesthesia and analgesia · May 2005
Randomized Controlled Trial Clinical TrialThe concentration-dependent effects of general anesthesia on spontaneous baroreflex indices and their correlations with pharmacological gains.
Beat-to-beat assessment of spontaneously occurring fluctuations in heart rate and arterial blood pressure allows noninvasive determination of cardiovagal function, but little is known regarding the effects of general anesthesia on spontaneous baroreflex (SBR) indices. We examined (a) concentration-dependent effects of sevoflurane on SBR indices, heart rate variability (HRV), and blood pressure variability and (b) correlation and agreement between pharmacological baroreflex gains and SBR indices during sevoflurane anesthesia. Continuous electrocardiogram and invasive arterial blood pressure were monitored in nine healthy volunteers before, during, and for 3 h after sevoflurane anesthesia, during which end-tidal sevoflurane was maintained at 0.7%, 1.4%, and 2.0% in random sequences. ⋯ Spontaneous sequence indices and high- and low-frequency powers of HRV demonstrated concentration-dependent depression. Pharmacological gains and SBR indices during anesthesia generally correlated well, but Bland-Altman analysis revealed that SBR indices had limits of agreement as large as the baroreflex gain itself. These data suggest that spontaneous indices are inadequate estimates of, and are inconsistent with, the pharmacological baroreflex gain during sevoflurane anesthesia.
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Anesthesia and analgesia · May 2005
Comparative StudyA comparison of the Vasotrac with invasive arterial blood pressure monitoring in children after pediatric cardiac surgery.
The Vasotrac is a device that provides near-continuous and noninvasive arterial blood pressure monitoring and may be an alternative to direct intraarterial measurement. It has been evaluated in adult patients, but minimal information is available for pediatric patients. We evaluated agreement between measurements of arterial blood pressure and heart rate obtained from the Vasotrac versus an arterial catheter in a pediatric population. ⋯ There was excellent agreement between arterial blood pressure measurement methods. Absolute mean differences based on mixed-model regression with 95% confidence intervals were 4.0 mm Hg (3.0-5.0 mm Hg), 4.3 mm Hg (3.1-5.5 mm Hg), and 3.5 mm Hg (2.5-4.0 mm Hg) for systolic blood pressure, diastolic blood pressure, and mean blood pressure, respectively. Arterial blood pressure measurements obtained from the Vasotrac agreed well with invasive arterial monitoring in pediatric patients.
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Anesthesia and analgesia · May 2005
Electroencephalogram monitoring during anesthesia with propofol and alfentanil: the impact of second order spectral analysis.
Bispectral analysis of the electroencephalogram (EEG) has been used for monitoring anesthesia. The estimation of bicoherence allows us to determine whether a given time series represents a linear random process in cases where the bicoherence is trivial, i.e., a mere constant independent of frequency. In this study, we investigated the proportion of EEG epochs with nontrivial bicoherence during surgical anesthesia with propofol and alfentanil as an indicator for the degree of nonlinearity in the EEG. ⋯ Under these conditions, the EEG can be considered as a linear random process. Our findings suggest that the spectral information in the frequency domain delivered by the EEG monitoring during anesthesia is largely contained in the power spectrum of the signal. This calls into question the benefit of EEG bispectral analysis for monitoring anesthesia effect.
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Anesthesia and analgesia · May 2005
Case ReportsDesflurane, malignant hyperthermia, and release of compartment syndrome.
We describe a case of suspected malignant hyperthermia in a healthy 20-yr-old man. The patient underwent urgent release of upper extremity compartment syndrome as a result of traumatic vascular injury. ⋯ Treatment with dantrolene and supporting measures restored cardiovascular stability. Three days later he underwent a successful second surgery under regional block with total IV anesthesia.