Medline ® Abstracts for References 46,67-69

An experimental and clinical tehcnique of measuring tissue pressures within closed compartments demonstrates a normal tissue pressure is approximately zero mmHg, and increased markedly in compartmental syndromes. There is inadequate perfusion and relative ischemia when the tissue pressure within a closed compartment rises to within 10-30 mm Hg of the patient's diastolic blood pressure. Fasciotomy is usually indicated, therefore, when the tissue pressure rises to 40-45 mm Hg in a patient with a diastolic blood pressure of 70 mm Hg and any of the signs or symptoms of a compartmental syndrome. There is no effective tissue perfusion within a closed compartment when the tissue pressure equals or exceeds the patient's diastolic blood pressure. A fasciotomy is definitely indicated in this circumstance, although distal pulses may be present. The measurement of tissue pressure aids in the early diagnosis and appropriate treatment of compartmental syndromes.

Surgical decompression remains the only effective treatment for the ischemia of the muscles and nerves of the leg that constitutes the principal defects in the compartment syndromes. Recently, partial fibulectomy has been proposed as a good way to decompress all four compartments instead of the older double incision. Both methods are effective in satisfactorily reducing intracompartmental pressures, as documented by our wick catheter measurements. However, the double-incision technique is easier, faster, safer, and is the treatment of choice when four-compartment decompressive fasciotomy is indicated.

A new catheter employing a different technique to monitor compartmental pressure has been developed. The accuracy of the catheter was compared to a wick catheter and to the needle manometer technique for monitoring compartmental pressure. The slit catheter is the most accurate of the three techniques for continuous pressure monitoring for periods of up to 24 hours in the experimental canine model. The slit catheter is as accurate as the wick catheter for pressure measurements from 0 through 10 mm Hg. The needle technique has proven to be the least accurate of the three.

Laboratory and clinical tests were carried out to determine the clinical usefulness, validity, and safety of a new self-calibrating, battery-powered monitoring system for the measurement of intramuscular pressure with use of an electronic transducer-tipped catheter. The eight probes accurately recorded applied pressures ranging from zero to 160 millimeters of mercury (zero to 21.33 kilopascals). The system registered little temperature-induced drift (maximum, 1.25 millimeters of mercury [0.17 kilopascal]) between dry room temperature and 40 degrees Celsius. There were also minimum variations (range, -0.14 to 0.81 millimeter of mercury [0.02 to 0.11 kilopascal]) in the pressures recorded during a twenty-four-hour period. The resting pressure in the tibialis anterior muscle of twenty volunteers who had normal limbs was a mean (and standard deviation) of 13.1+/-8.3 millimeters of mercury (1.75+/-1.11 kilopascals). There was a good correlation between externally applied pressures (zero, twenty, forty, sixty, eighty, and 100 millimeters of mercury [zero, 2.67, 5.33, 8.00, 10.66, and 13.33 kilopascals]applied with use of antishock trousers) and the pressures measured in the tibialis anterior muscle of four volunteers (r = 0.997 to 0.999). The injection of sterile saline solution into the tibialis anterior muscle of a volunteer and the use of high-frequency recording during muscular activity showed a high degreeof responsiveness and sensitivity to changes in intramuscular pressure. We also prospectively evaluated the clinical usefulness of the system and found it to be easy to assemble, calibrate, and use. Thus, this reusable, electronic transducer-tipped catheter system, which is based on a noninfusion technique, is simple, minimally traumatic, and highly precise. It is free of hydrostatic pressure artifacts and provides dynamic responses to changes in intramuscular pressure.