RESUMO
The purpose of this study was to quantitate the intracellular high-energy phosphate compounds during 6 hours of tissue ischemia in the anterior tibial compartment of beagles subjected to an induced traumatized compartment syndrome. The goal of this work was to provide clinicians with objective criteria to augment clinical judgment regarding surgical intervention in the impending compartment syndrome. A beagle model was utilized in which the Delta pressure (difference between the mean arterial pressure and compartment pressure) could be controlled. The model, in conjunction with 31P-magnetic resonance spectroscopy (MRS), allowed a measure of high-energy phosphate compounds and pH in the compartment at various Delta pressures. The extent of ischemic metabolic insult in the compartment was then quantitated. Our data suggest the following: 1) lower Delta pressures result in a proportionally greater drop in the intracellular phosphocreatine ratio and pH; 2) at lower Delta pressures, there is proportionally greater decline in the percentage recovery post-fasciotomy; 3) blood pressure is extremely important and periods of hypotension may result in increased muscle damage at lower compartment pressures.
Assuntos
Síndrome do Compartimento Anterior/metabolismo , Síndromes Compartimentais/metabolismo , Metabolismo Energético , Fósforo/metabolismo , Animais , Síndrome do Compartimento Anterior/fisiopatologia , Pressão Sanguínea , Modelos Animais de Doenças , Cães , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Masculino , Microscopia Eletrônica , Músculos/metabolismo , Músculos/ultraestrutura , Fósforo/análise , Radioisótopos de Fósforo , Fatores de TempoRESUMO
In an experimental ischemic compartment syndrome in dogs, phosphorus (31P) nuclear magnetic resonance (NMR) spectroscopy was used to determine the tissue pressure threshold at which resting skeletal muscle begins to use anaerobic energy sources due to insufficient cellular oxygen delivery. The interactive effects of systemic perfusion pressure and moderate muscle trauma on this anaerobic threshold were also evaluated. The severity of cell injury produced by various degrees of compartment pressurization over an eight-hour period was concomitantly studied using muscle biopsy and electron microscopy. Clinical correlation of a preliminary patient series studied using 31P-NMR demonstrated that the threshold for cellular metabolic derangement in skeletal muscle subjected to increased tissue pressure was more closely associated with the difference between mean arterial blood pressure (MABP) and compartment pressure than with the absolute compartment pressure alone. The difference is termed MABP-compartment pressure, or delta P. The lowest delta P at which a normal cellular metabolic state can be maintained is approximately 30 mmHg in normal muscle and 40 mmHg in moderately traumatized muscle. It is imperative to interpret compartment pressure measurements in light of the degree of soft tissue trauma sustained and the patient's blood pressure, as well as the clinical signs and symptoms.