Central Neurogenic Hyperventilation and Hyperlactatemia After Resection of a Fourth Ventricle Tumor: A Case Report.

We report a rare case of central neurogenic hyperventilation (CNH) and hyperlactatemia after resection of a fourth ventricle tumor. Our management consisted of close monitoring and exclusion of alternate causes of hyperventilation and hyperlactatemia. We hypothesize that a localized increase in tissue lactate, related to tumor metabolism, may have triggered CNH in our patient through stimulation of the brainstem respiratory centers. CNH should be considered during the differential diagnosis of perioperative hyperventilation with respiratory alkalosis in patients with posterior fossa tumors. Hyperlactatemia can trigger compensatory hyperventilation but will not result in alkalosis.

Vital capacity and patient controlled sevoflurane inhalation result in similar induction characteristics.

PURPOSE: To compare patient controlled inhalational induction (PCI) with the most commonly used sevoflurane induction technique, vital capacity inhalational induction (VCI). METHODS: Following approval of the Research Ethics Board, 124 outpatients undergoing knee arthroscopy were randomly assigned to receive either PCI or VCI sevoflurane followed by laryngeal mask airway (LMA) insertion and sevoflurane maintenance. In the PCI group, the circle circuit was not primed. The patients were asked to hold the facemask themselves and breathe normally with sevoflurane 8% in oxygen at a flow rate of 4 L x min(-1). In the VCI group, the circle circuit was primed and patients were asked to take vital capacity breaths with sevoflurane 8% at an oxygen flow rate of 8 L x min(-1). The LMA was inserted as soon as the patient's jaw was relaxed. Time from induction to LMA insertion was recorded and insertion conditions rated. The amount of sevoflurane used for LMA insertion was calculated. Vital signs were monitored at one-minute intervals until ten minutes after LMA insertion. RESULTS: Demographic data were comparable. There were no differences with respect to LMA insertion time (PCI - 3.4 min vs VCI - 3.3 min), laryngospasm (PCI - 7% vs VCI - 5%), mean arterial pressure, heart rate, SaO(2) as well as patient's overall satisfaction. CONCLUSION: PCI was comparable to VCI in sevoflurane induction with respect to the speed of induction, side effects during induction and patient satisfaction. However, PCI requires no special training and is widely applicable to all patient populations.

Venous air embolism during awake craniotomy in a supine patient.

PURPOSE: To report a non-fatal case of intraoperative venous air embolism (VAE) during an awake craniotomy. VAE presented with unusual clinical features. CLINICAL FEATURES: VAE during an awake craniotomy has not been reported frequently. The patient we describe presented with persistent coughing followed by tachypnea, hypoxia and reduction in end-tidal CO(2) during dural opening while undergoing an awake craniotomy in the supine position. Cardiovascular variables were stable during the episode except for transient hypertension. Having ruled out airway obstruction and low cardiac output, we concluded that air embolism was the cause. The patient responded immediately to the standard treatment of air embolism and recovered without any complication. CONCLUSION: This case illustrates a VAE during an awake craniotomy and emphasizes the importance of early diagnosis in the management.