Lung Impedance Guided Preemptive Treatment of Evolving Pulmonary Congestion-Edema in Course of Acute Myocardial Infarction Reduces Use of Furosemide

Abstract

Patients sustaining an acute myocardial infarction (AMI) frequently develop pulmonary congestion-edema (PED) during hospitalization. Treatment is initiated after the appearance signs of lung fluid content (LFC) increase. Ongoing monitoring of LFC may enable to predict impending PED and prompt preemptive therapy. Late treatment beginning of PED may require more diuretics. We sought to find out whether non-invasive lung impedance (LI) guided preemptive treatment of evolving PED with furosemide in the course of AMI may reduce dosage of furosemide administered in comparison with common practice. LI was measured by a method based on transverse distribution of electromagnetic energy through the chest which is more sensitive than current methods. We previously found that an LI decrease of 12-14% from baseline level, when patients are still asymptomatic, reflects the beginning of transition from interstitial to alveolar edema. In this study we evaluated the effect of preemptive LI-guided therapy on furosemide dosage required to treat evolving PED. 222 AMI consecutive patients asymptomatic at admission in which an LI decrease of 12-14% from initial level was recorded during monitoring were randomized into two groups (2:1). Groups were well matched for demographic, laboratory parameters, reperfusion type and in-hospital therapy. Patients were monitored for 118±50 hours. Treatment for PED was started in group 1 patients (common practice) only after symptom appearance (LI decrease 25.3±5.2% from initial) while group 2 patients diuretic preemptive therapy was begun at an asymptomatic stage when LI decreased by 12-14%. All group 1 patients but only 11% of group 2 patients developed moderate to severe clinically and roentgenologically proven PED (p<0.001). During admission group 1 patients were treated with more furosemide than group 2 patients (316±357 mg vs. 184±159 mg, p<0.05). Time from LI decrease by 12-14% to initiation of therapy with furosemide was longer in group 1 by 545±339 minutes than in group 2 (p<0.001). Patients of group 1 and 2 required furosemide treatment during 3.2±2 vs. 2.4±1.7 days, respectively (p<0.05). Preemptive LI-guided therapy with furosemide in AMI patients is initiated earlier than in common practice and is effective in halting evolving PED.