Purpose: Continuous monitoring of the interstitial pressure of muscle compartments is a useful method for preventing compartment syndrome. The perfusion pressure is the key measurement (difference between the arterial diastolic pressure and the interstitial pressure). It should always remain above 30 mm Hg. Our postoperative monitoring data provided new insight into circumstances where there is a higher risk of compartment syndrome due to a fall in arterial diastolic pressure.

Material and methods: Twenty patients (13 boys and 7 girls) underwent continuous monitoring of the interstitial pressure of the anterolateral compartment of the lower limb. These children had undergone lengthening-realignment procedures, realignment procedures, or treatment of fracture. Mean age was 11.5 years. Preventive subcutaneous aponeurotomy was performed in 15 patients. The patients were monitored for a mean 55 hours. The interstitial pressure was noted every hour, in addition to pain on a visual scale, and the type and administration route of antalgesics. A risk condition was defined as perfusion pressure (diastolic arterial pressure – interstitial pressure) less than 30 mmHg.

Results: One or more episodes of low perfusion pressure (< 30 mmHg) were observed in eleven of the twenty patients, during the first five postoperative hours in five and during sleep and awakening phases in eight. Pain was not increased during these periods during which antalgesics were administered. The common denominator for these risk conditions was high pressure in the muscle compartment but low diastolic pressure. None of the children developed a compartment syndrome with sequela. Preventive aponeurotomy did not protect against the development of these risk conditions.

Discussion: These results provide new insight into the haemodynamic conditions occurring during the recovery period and point out the need for rapid recovery of an elevated diastolic arterial pressure. This would decrease the risk of compartment syndrome and also limit postoperative oedema.

Conclusion: Immediate postoperative monitoring of the interstitial pressure demonstrated that the risk of compartment syndrome occurs when the diastolic pressure is low, that is during postoperative awakening and periods of sleep in children given antalgesics.