End-tidal CO2 monitoring in mitral stenosis patients undergoing closed mitral commissurotomy.

Arterial to end-tidal carbon dioxide difference (P(a-E')CO2) was recorded in 20 mitral stenosis patients (group A) for closed mitral commissurotomy and 20 healthy individuals (group B) for elective limb surgery. Mitral stenosis patients showed a greater difference than group B patients. Repeated measurements of P(a-E')CO2 in mitral stenosis patients at various stages of closed mitral commissurotomy not only showed a mean increase from before thoracotomy but there was also no correlation between P(a-E')CO2 before thoracotomy with that after thoracotomy, after commissurotomy or after chest closure. This indicated that end-tidal CO2 monitoring was unsuitable to measure adequacy of ventilation during closed mitral commissurotomy.