Severe bradycardia and hypotension after connecting negative pressure to the subgaleal drain during craniotomy closure.

Negative pressure drainage systems are often used after craniotomy for evacuation of potential bleeding. There are several reports of haemodynamic disturbances with epidural negative pressure drainage, but such reports are very few for subgaleal drains placed over the bone flap. We report a case in which a patient developed severe cardiovascular disturbances after the vacuum drainage was connected to a subgaleal drain after craniotomy for aneurysm clipping. The patient had no significant cardiac history, had an uneventful intra-operative course and yet developed bradycardia and hypotension, which were reproducible and severe enough to require atropine administration. Anaesthetists must be aware of these effects, so that they can anticipate and treat such complications.

Use of a gum elastic bougie to facilitate blind nasotracheal intubation in children: a series of three cases.

Management of a difficult paediatric airway is challenging, and the unavailability of a paediatric fibreoptic bronchoscope, a common limitation in developing countries, adds to these difficulties. Children with bilateral temporomandibular joint ankylosis have limited mouth opening and therefore direct laryngoscopy and intubation is not usually possible. In the absence of sophisticated fibreoptic equipment, blind nasal intubation remains the only non-surgical option for control of the airway. Blind nasal intubation in paediatric anaesthesia is difficult. We describe a novel method of blind nasal intubation in paediatric patients using a gum elastic bougie. We have used this method successfully in three patients in whom tracheal intubation using a conventional blind nasal approach was unsuccessful. In view of its reliability and the absence of any soft tissue injury, we propose the use of this novel technique as an alternative to conventional blind nasal intubation, when more sophisticated fibreoptic equipment is not available.

Influence of ventilator settings in determining respiratory frequency during mechanical ventilation.

During mechanical ventilation, changes in inspiratory flow and tidal volume (VT) have been shown to alter respiratory frequency (f ). However, the changes in flow and VT have been accompanied by alteration in ventilator inspiratory time (TI,(vent)), and it is not clear which variable is the primary determinant. To address this issue, we employed four protocols in 15 healthy volunteers receiving assist-control ventilation. When VT was fixed and flow was delivered at 30, 60, and 90 L/min, f increased as a function of the increase in flow and the decrease in TI,(vent). When flow was held constant and VT was changed among 0.5, 1.0, and 1.5 L, f increased as a function of the decreases in VT and TI,(vent). When flow was increased from 60 to 90 L/min and these changes were balanced with VT settings of 1.0 and 1.5 L to maintain a constant TI,(vent), f did not change. When flow and VT were held constant and TI,(vent) was varied by the application of inspiratory pauses (0 to 2 s), f decreased as a function of the increase in TI,(vent) (p < 0.001). In conclusion, the imposed ventilator inspiratory time during mechanical ventilation can determine f independently of delivered inspiratory flow and VT.