ObjectiveTo evaluate the benefit of recombinant human growth hormone administration on muscle strength and duration of weaning in critically ill patients undergoing prolonged mechanical ventilation.DesignProspective, randomized, controlled, single-blind study.SettingIntensive care unit.PatientsTwenty patients requiring more than equals 7 days of mechanical ventilation for acute respiratory failure.InterventionRandom assignment to receive either 0.43 IU (approximate 0.14 mg) recombinant growth hormone/kg body weight/day (treated group), or saline (nontreated group) for 12 days.Measurements and Main ResultsNutritional support was guided by indirect calorimetry. Cumulative nitrogen balance was positive throughout the study period in the treated group (44.9 plus minus 17.3 [SEM] g/12 days) vs. the nontreated group (minus 65.8 plus minus 11.8 g/12 days) (p less than .0001). Despite similar initial plasma concentrations, recombinant growth hormone supplementation resulted in marked increases in growth hormone, insulin like growth factor-1, and insulin concentrations (p less than .05, .02, and .0001, respectively, vs. nontreated group). Body impedance determined net fat-free mass increased in the treated group (0.8 plus minus 0.6 kg) vs. the nontreated group (minus 1.1 plus minus 0.5 kg) (p less than .03). Initial peripheral muscle function, assessed by computer-controlled electrical stimulation of the adductor pollicis, was similarly lower in treated and nontreated groups than sex and age-matched normal controls, and decreased further during the study period. Arterial blood gases, cumulative total mechanical ventilation time, and number of hrs/day of mechanical ventilation during weaning were similar in both patient groups. Only three of the ten patients in each group were weaned from mechanical ventilation by day 12.ConclusionsDaily administration of recombinant growth hormone in mechanically ventilated patients with acute respiratory failure promotes a marked nitrogen retention. However, this action is accompanied neither by an improvement in muscle strength nor by a shorter duration of ventilatory suppport.(Crit Care Med 1996; 24:403-413)