The non-pneumatic anti-shock garment: How applier strength and body mass index affect external abdominal pressure

Objective: To assess the amount of abdominal pressure generated by the Non-pneumatic Anti-Shock Garment (NASG), a first-aid counter pressure device for obstetric hemorrhage, and to evaluate if body mass index (BMI) and applier strength, affect pressure. Study Design: A pilot study convenience sample of 20 non-pregnant volunteers underwent external abdominal pressure monitoring with NASG placement. Mean pressure and the effects of BMI and applier strength were examined. Results: The mean external abdominal pressure significantly increased from 1.0 mmHg at baseline to 67 mmHg on NASG application, returning to 1.0 mmHg upon removal (p=0.005). Greater mean pressure was exerted by a strong applier versus a weak applier, irrespective of BMI (p<0.001). Pressure had an inverse relationship with BMI, particularly with a strong applier (r=-0.905, p<0.001). The difference between pressures achieved in an underweight patient with a strong applier and an overweight patient with a weak applier was significant (73.2 vs 35.7 mmHg; p=0.051). Conclusion: This pilot study demonstrates a significant increase in abdominal pressure with device application and significant variation with BMI and applier strength. These findings may have important implications for optimizing device usage.