Cuff pressure and microvascular occlusion in the tracheal mucosa. An intravital microscopic study in the rabbit.

A method is described for the intravital microscopic observations of rabbit tracheal mucosa microcirculation during compression with a thin, transparent high volume cuff. The cuff pressure (CP) required to cause complete ischemia in the mucosa over the cartilages was measured and a correlation was found to the mean arterial blood pressure (MAP). Ischemia was not observed below CP-MAP ratios of 0.40 for untreated animals or below 0.44 for animals where the MAP had been elevated by adrenalin. However, marked reduction of the microvascular blood flow was present at lower CP-MAP ratios, 0.2-0.3, which at a MAP of 75 mmHg corresponds to cuff pressures of 15-20 mmHg. It is therefore advocated that endotracheal cuff pressures are kept below these values to avoid ischemic tissue injury.