Introduction and Aims: Limb occlusion pressure directly measures the cuff pressure required to occlude blood flow. We determined if a plethysmographic technique of limb occlusion pressure measurement could be used clinically and compared limb occlusion pressures for wide contoured cuffs versus standard narrow cuffs.

Method: A photoplethysmograph sensor and a handheld module containing the required hardware and software were added to a standard Zimmer ATS 2000 tourniquet. Twenty patients undergoing elective foot and ankle surgery were randomised to either a wide contoured cuff or a regular cuff. Limb occlusion pressure and quality of the bloodless surgical field were recorded. Cuff pressure was selected using an incremental increase of pressures over the limb occlusion pressure. Cuff pressures were compared between cuff types and were also compared to the cuff pressure selected by most surgeons determined by a previous survey.

Results: Three out of 40 patients had poor fields. Fifty-two patients were recruited and 12 patients were excluded due to difficulty obtaining a limb occlusion pressure measurement. The mean LOP in the wide cuff group was 36 mmHg lower than the standard cuff group (P = 0.004, 80% power to detect a reduction of 25 mmHg). The cuff pressure using the recommended tourniquet pressure (RTP) and a standard cuff was an average of 58 mmHg lower than 300 mmHg, and 108 mmHg lower than 350 mmHg. For the wide cuff and using the RTP the pressure was 98 mmHg lower than 300 mmHg, and 148 mmHg lower than 350 mmHg. There was a poor relationship between limb occlusion pressure and systolic blood pressure.

Conclusion: Tourniquet pressures can be reduced by one-third using limb occlusion pressure measurement and a wide contoured cuff without increasing the number of poor operative fields. Traditional techniques of setting the tourniquet, such as using systolic blood pressure, are likely to result in poor fields or excessive tourniquet pressures. The plethysmographic method is accurate and practical for clinical use.