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Crushing injury of the hand; prevention of ischemic contracture.

Crushing injury of the hand usually causes "explosive" damage. Subsequent swelling of the palmar structures further impairs venous outflow, and hemorrhage into structural spaces increases the pressure. The arterial system and the large dorsal veins, however, are seldom obstructed and provide adequate circulation unless hampered by improper bandaging. A bandage that compresses the dorsal veins causes back-pressure, which increases the swelling further and brings about ischemia. Swelling and pain cause the patient to restrict exercise of the injured hand, which permits contractures to develop. The author has averted this sequence in more than 100 cases by preserving integrity of veins during debridement, arresting hemorrhage, bandaging the hand with compression dressings in functional flexion, and reducing swelling with hyaluronidase. In these cases, on removal of bandages in 24 hours, swelling was reduced and continued to diminish. All patients exercised the hand at this time without discomfort and only a few required aspirin for pain.

Bandages↗

Role of endothelin-A receptors in ischemic contracture and reperfusion injury.

BACKGROUND: Circulating endothelin (ET)-1 is elevated in ischemia/reperfusion and may exert proischemic effects. The aim of the present study was to characterize the effects of ET-1 in rat isolated hearts using subtype-selective ET receptor antagonists, agents modulating the cytosolic Ca2+ concentration, or the activity of cGMP-dependent protein kinase. METHODS AND RESULTS: Rat hearts perfused at constant pressure were made ischemic by reducing flow to 0.2 mL x min(-1) x g(-1), followed by reperfusion at normal pressure (each phase, 25 minutes). Drugs were infused during the ischemic phase only. Parameters monitored were extent and time-to-onset of contracture in ischemia, left ventricular developed pressure (LVDevP), coronary flow (CF), and diastolic relaxation during reperfusion. The ET(A) receptor-selective antagonist PD 155080 (50 nmol/L) reduced peak ischemic contracture (-49%) and delayed its time to onset (+56%) and improved recovery of reperfusion LVDevP (+12%), CF (+16%), and diastolic relaxation (+50%). Infusion of an ET(A)/ET(B)-nonselective antagonist, PD 142893 (200 nmol/L), had similar effects on all parameters, whereas infusion of BQ-788 (20 nmol/L), an ET(B) receptor-selective antagonist, was without effect. Exogenous ET-1 (100 pmol/L) hastened contracture and increased its extent (+23%) and reduced recovery of both LVDevP (-31%) and CF (-18%), effects that were counteracted by HOE 642 (10 micromol/L), a Na+/H+ exchange inhibitor, but not by nicardipine (30 micromol/L), a Ca2+ entry blocker; activation of cGMP-dependent protein kinase by the cell-permeable cGMP analog Sp-8-p-chlorophenylthioguanosine-3',5'-cyclic monophosphorothioate (10 micromol/L) improved function without preventing the effects of ET-1. CONCLUSIONS: The data indicate that ET-1 exacerbates ischemic contracture and worsens ventricular and coronary reperfusion dysfunction by activating ET(A) receptors via a mechanism likely involving activation of Na+/H- exchange in this model.

Animals↗