Better flat than faint

I do not know how it started, but in recent times there has been a fad for recovering patients in the semi recumbent position before they emerge from sevoflurane/LMA anaesthesia. Often, in the PACU there is a row of pale patients flagging away on their LMA plastic breathing bags with a brachial systolic pressure in the 80s or 90s. The pressure in the brain is thus likely to be about 70: only marginally over the critical cerebral perfusion pressure and in a brain which has a sevoflurane-addled autoregulation.

Fuchs et al (J Neurosurg Anesthesiol. 2000 Apr) looked at the influence of position and sevo/N2O anesthesia on regional cerebral oxygen saturation and found that rSpO2 decreased significantly in the anaesthetised sitting position but not in the awake sitting position. Values were even worse in those with carotid stenosis. And VCCAMM has had cases of cerebral hypoperfusion that have occurred after shoulder surgery in which anaesthesia was by plexus blockade and LMA/sevoflurane.

So why position them this way? At the least it exposed the paient to the symptoms of postural hypotension in the early recovery period and at the worst it may cause critical cerebral ischaemia. There is usually little need to improve oxygenation because the patient is getting supplementary O2 and is monitored with oximetry. And usually they have managed in theatre in the lithotomy and head down position without hypoxaemia.

So keep them supine, if not lateral, until awake. Even a first-aider would not position an unconsious patient sitting up!