In common with other volatile anesthetic agents, sevoflurane has an intrinsic dose-dependent cerebral vasodilatory effect. However, this effect is less than that of isoflurane.

We have examined cerebral pressure autoregulation while awake, and during 0.5 and 1.5 MAC of sevoflurane anaesthesia in 10 patients undergoing non-intracranial neurosurgical procedures. All patients received a standardized anaesthetic comprising premedication with temazepam 20 mg orally, a sleep dose of propofol, fentanyl 1 microgram kg-1 and vecuronium 0.1 mg kg-1. After tracheal intubation, the lungs were ventilated with a mixture of air and oxygen to mild hypocapnia. Routine monitors included ECG, continuous and intermittent non-invasive arterial pressure, pulse oximetry and end-tidal capnography. In addition, blood flow velocity (vmca) was measured by insonating the middle cerebral artery transtemporally using a 2-MHz transcranial Doppler probe. Cerebral pressure autoregulation was tested by increasing mean arterial pressure (MAP) by approximately 20 mm Hg using an infusion of phenylephrine and simultaneously recording vmca. The index of autoregulation (IOR) during each period of the study, calculated as the ratio of percentage change in estimated cerebral vascular resistance (CVRe = MAP/vmca) to percentage change in MAP, was compared using ANOVA. vmca during 0.5 and 1.5 MAC of sevoflurane anaesthesia was significantly lower than that while awake (mean 79 (SD 24), 54 (15) and 51 (12) cm s-1, respectively; P < 0.05). There was no significant change in vmca with the increase in MAP while awake, or during 0.5 or 1.5 MAC of sevoflurane anaesthesia and IOR was similar under the three conditions (0.82 (0.11), 0.83 (0.04) and 1.0 (0.03), respectively). We conclude that cerebral pressure autoregulation remained intact during sevoflurane anaesthesia in humans.

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Three cases of pharmacobezoars are reported to demonstrate typical autopsy findings and potential lethal mechanisms: (i) A 32-year-old woman died following an overdose of prescription medications. A gelatinous pharmacobezoar was found forming a cast of her bronchial tree. (ii) A 24-year-old woman also died following an overdose of prescription medications. At autopsy, two pharmacobezoars were present, one within the larynx and another occluding the right main bronchus. Deaths in both cases were attributed to airway occlusion by pharmacobezoars complicating mixed drug toxicity. (iii) A 79-year-old man was found dead in a car. Death was attributed to the combined effects of carbon monoxide and drug toxicity with a large pharmacobezoar lodged within the esophagus. Pharmacobezoars are specific types of bezoars that occur when pharmaceutical materials, such as tablets, suspensions, and/or drug delivery devices, aggregate and contribute to death by occluding airways with tenacious material or by eluting drugs.

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