From the Journal archives: Airway closure and lung volumes in surgical positions.
Douglas B. Craig, W.M. Wahba, Hillary Don


BACKGROUND
Can Anaesth Soc J 1971; 18: 92-9.


OBJECTIVE
Surgery and anesthesia expose patients to moderate and sometimes extreme positioning changes that are often unphysiological. The purpose of this article is to highlight and contextualize a seminal study from the Journal archives that explores the effect of several commonly utilized surgical positions (supine, Trendelenburg and lithotomy) and age on basic lung volumes as well as the volume at which small airway closure (AC) (also known as closing volume [CV]) occurs. These factors were examined with the aim of determining which patient position variables could be of clinical significance to gas exchange in the perioperative period.


RESULTS
This work showed that supine positioning, when compared with the seated position, results in a decrease of all lung volumes and capacities, including functional residual capacity (FRC) and CV. Trendelenburg positioning further decreases FRC, with no further changes induced by lithotomy positioning. Age is a clinically important factor in AC, occurring within the tidal volume range at a lower age when supine as compared with the seated position.


CONCLUSIONS
The work of Drs. D. Craig et al. published in the Journal more than 40 years ago was seminal to our understanding of how patient positioning has an important influence on lung volumes and on the age-related relationship between FRC and CV.
Departments of Anesthesia & Perioperative Medicine and Surgery, St. Boniface Hospital, University of Manitoba, CR3008 - 369 Tache Avenue, Winnipeg, MB, R2H 2A6, Canada, hgrocott@sbgh.mb.ca.
Hilary P
HP
Grocott
D006801:Humans; D008168:Lung / Q000502:physiology*; D008297:Male; D011187:Posture; D012119:Respiration; D013514:Surgical Procedures, Operative