Joanne J. Nicks

Efficacy of theophylline for prevention of post-extubation respiratory failure in very low birth weight infants†

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1554 efficacy of theophylline for prevention of post-extubation respiratory failure in INFANTS LESS THAN 1250 GRAMS

Because methylxanthines modulate apnea and enhance intercostal and diaphragmatic contractility, we hypothesized that administration of theophylline to infants < 1250 gm on low ventilatory settings would facilitate extubation and prevent post-extubation respiratory failure. A prospective, randomized, blinded, placebo-controlled trial was performed. Twenty-five infants [11 placebo (P), 14 treated (T)] who were < 1250 grams on assisted ventilation with FiO2 ≤ .30, PIP ≤ 20, IMV ≤ 10 were enrolled. Electrolyte abnormalities and anemia were corrected before entry and absence or stability of IVH was confirmed by cranial sonography. Prior to extubation, T infants received 6 mg/kg theophylline loading dose IV or PO and then a maintenance dose 2 mg/kg q 12h for 5 doses. Control infants received equal volumes of normal saline. No significant differences existed between groups for birthweight, GA, duration of ventilation, and peak FiO2. Nine of 14 T infants and only 1 of 11 P infants were successfully extubated for at least 5 days (p=0.01). Of 5 T infant failures, 2 had congestive heart failure with patent ductus arteriosus and 3 had severe apnea. Of 10 P infant failures, 8 had recurrent apnea and 2 failed to wean from the respirator during the study period. Seven of 9 P infants were later successfully extubated with theophylline. We conclude that theophylline therapy prior to extubation of infants < 1250 gms is effective in preventing post-extubation respiratory failure.

DO PATIENT CHARACTERISTICS PREDICT RESPONSE TO INHALED NITRIC OXIDE FOR NEONATAL PERSISTENT PULMONARY HYPERTENSION? 1973

DO PATIENT CHARACTERISTICS PREDICT RESPONSE TO INHALED NITRIC OXIDE FOR NEONATAL PERSISTENT PULMONARY HYPERTENSION? 1973

ADULT RESPIRATORY DISTRESS SYNDROME (ARDS) IN NEONATES: A CLINICAL SYNDROME

Since 1984 we have cared for 11 neonates with severe respiratory distress whose clinical characteristics appear distinctive: 1) full-term by obstetric and Dubowitz criteria (median 39 wks, range 37-42; median BW 2950g, range 2610-4360), 2) diffuse alveolar disease radiographically, 3) requiring FiO2 1.0 and mechanical ventilation to maintain paO2 50, 4) absence of other conditions known to produce a similar clinical profile. No mothers were diabetic or Rh-sensitized. Blood cultures and latex agglutination bacterial antigen studies were negative in all. None had aspirated meconium. Two-dimensional echocardiography and simultaneous pre- and postductal ABGs showed no evidence of cyanotic congenital heart disease or extrapulmonary right-to-left mix. Among the 11, 5 had 5 minute Apgar scores ≤5, 8 had evidence of fetal distress, 5 had initial hematocirts <45, and 7 had hypotension or oliguria requiring pressors and/or volume support. Seven had multiple organ dysfunction. AH 11 survived but required prolonged mechanical ventilation and supplemental oxygen. Trials of hyperventilation (pH ≥7.55, paCO2 ≤25) in 8 and tolazoline in 4 failed to increase paO2 by >20 torr. Among 7 infants who underwent trials of increased PEEP to ≥6 cm H2O (range 6-10) without other concurrent changes in ventilator settings, 6 responded with prompt increases in paO2 >20 torr (median 68, range 22-136), despite resultant mean airway pressure (PAW) being lower than previously unsuccessful PAWs in 4 of 6. We suggest that ARDS is a distinctive clinical entity in neonates. A trial of PEEP ≥6 cm H2O should be considered in full-term infants with severe respiratory distress in whom other causes can be excluded.

EFFECTS OF HIGH FREQUENCY JET VENTILATION ON PULMONARY AND HEMODYNAMIC PARAMETERS IN A RABBIT MODEL

In order to assess the effects of high frequency jet ventilation (HFJV) on pulmonary and hemodynamic parameters, 10 anesthetized adult rabbits (1.8-2.2 kg) were studied while receiving HFJV and conventional mechanical ventilation (CMV). Each rabbit received two hours of one ventilatory mode, then two hours of the other. HFJV was delivered by a Sechrist 990 HFJ ventilator while CMV was delivered by a Sechrist IV-100 B infant ventilator. Prior to data collection ventilation in both modes was adjusted to maintain the PaCO2 between 35 and 45 Torr. CMV was accomplished using a peak inspiratory pressure of 12 cm H2O and 4 cm H2O end expiratory pressure. Ventilatory rates of 300 (six rabbits) and 600 (four rabbits) breaths per minute were used during HFJV. In both modes FiO2 was 0.5 and flow rate was 10 L/min. Pulmonary gas exchange (A-a DO2), venous saturation (SvO2), mean airway pressure (MAP), heart rate (HR), mean arterial blood pressure (BP), and central venous pressure (CVP) were recorded every 30 minutes (Table). The results suggest no impedance to pulmonary gas exchange, a lower MAP, and improved hemodynamic stability with HFJV compared to CMV in the adult rabbit.