Muscular compartment syndrome and in vivo optical spectroscopy monitoring: a new model

n/

Reciprocal influence of refractory hypoxemia and high intracranial pressure on the postoperative management of an urgent neurosurgical procedure.

A 20-year-old man was admitted in the neurology ICU after the drainage of a large frontal hematoma related to the spontaneous bleeding of a recently diagnosed cavernoma. On admission the Glasgow coma score was 4/15, with evidence of sub-falcorial herniation and elevated intracranial pressure. On the 4th postoperative day the patient developed acute lung injury, with an apparently normal bedside chest x-ray examination. Several episodes of critical oxygen desaturation (S(pO(2)) < 75%) occurred, which were not responsive to increasing PEEP and recruitment maneuvers. Hypoxemia was complicated by further increase in intracranial pressure. Ventilation in the prone position was not tolerated. The introduction of inhaled nitric oxide allowed a rapid and sustained improvement of both arterial oxygenation and cerebral hemodynamics. Interactions between acute brain and lung injury are complex. The correction of hypoxemia can usually be achieved by increasing PEEP or by alveolar recruitment maneuvers. Ventilation in the prone position can also be helpful in improving oxygenation, but is not always possible. The potential benefit of inhaled nitric oxide in similar cases has been described, but has still to be further explored

In vivo optical spectroscopy monitoring in a new model of muscular compartment syndrome

BACKGROUND: Muscular compartment syndrome (MCS) is a rare but serious postoperative complication. In vivo optical spectroscopy (INVOS) monitors continuously and non-invasively regional oxygen saturation (rSO(2)), and could predict the development of MCS. METHODS:In 10 healthy volunteers, we inflated a tourniquet to the mean arterial pressure to produce slight venous congestion and arterial hypoperfusion. Comparisons were made between the relative reduction in rSO(2) with baseline (deltaINVOS) and the time to observe motor nerve block (with non-invasive electromyography). Neurological symptoms, pain, and invasive intracompartmental pressure (ICP) were assessed. RESULTS: In the eight volunteers completing the protocol, we observed a profound motor nerve conduction block, immediately reversible. Baseline values were: [mean (sd)] INVOS: 73.3 (8.9)% and ICP: 16.9 (8.6) mm Hg. At the time of the block, values were: INVOS: 46.4 (10.9)%, deltaINVOS: 28.7 (10.6)%, and ICP: 70.0 (5.5) mm Hg. The time to reach the block was 33.0 (10.9) min, and to a deltaINVOS>10%: 27.4 (10.4) min. Receiver-operating characteristic curves demonstrated a similar accuracy of ICP and INVOS to predict the occurrence of the block. Twenty minutes with a deltaINVOS>10% or ICP>30 mm Hg were associated with a sensitivity and a specificity of 95% and 70%; or 91% and 65%, respectively. CONCLUSIONS: We have developed a model of acute immediately reversible MCS. Monitoring using the INVOS technology is as accurate as measurement of ICP, and could be a useful tool to prevent development of intraoperative MCS