Use of tolazoline in newborn infants with diaphragmatic hernia and severe cardiopulmonary disease

Extracorporeal membrane oxygenation following repair of congenital diaphragmatic hernias

From 1981 through 1986, 8 newborns with congenital diaphragmatic hernia required herniorrhaphy in the first 8 hours of life. Extracorporeal membrane oxygenation (ECMO) was employed in 7 after they met local criteria predictive of 95% mortality. These criteria were an alveolar-postductal arterial oxygen gradient greater than 600 mm Hg for 12 hours or hemodynamic instability. Four of these 7 patients had unremitting hypoxemia after herniorrhaphy (no "honeymoon" period), 3 of whom survived. One additional patient died, producing a mortality of 29%. ECMO used for 68 to 241 hours (mean, 163 hours) provided reliable oxygenation in all. Deaths resulted from disseminated intravascular coagulation and bleeding, and bleeding and pulmonary failure after ligation of a patent ductus arteriosus. Complications occurred in 6 patients and included bleeding (3), hernia recurrence (3), and air embolism (1). Follow-up ranging from 1 year to 6 years after discharge of the 5 survivors shows normal growth and development in 4. The reported mortality without ECMO following congenital diaphragmatic herniorrhaphy in the first 8 hours of life ranges between 60 and 80%. While bleeding may present problems, survival of newborns with refractory hypoxemia after diaphragmatic repair has improved with ECMO.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia continues to be a critical problem in neonatal surgery. Despite the apparent simplicity of the anatomic defect, the physiology is complex, and survival remains uncertain. Surgical success has been achieved, but we recognize that the barrier to survival is pulmonary parenchymal and vascular hypoplasia as well as the complex syndrome of persistent fetal circulation. In many ways the problem of diaphragmatic hernia is as much of an enigma to today's physician-scientist as it was to Bochdalek in the nineteenth century. The treatment of respiratory distress after repair of congenital diaphragmatic hernia has brought out the most creative and innovative efforts of pediatric surgeons in both the laboratory and the intensive care unit.

The early evaluation of survivors after extracorporeal membrane oxygenation for neonatal pulmonary failure

Excluding mortality data, there is little information regarding patients' development after extra corporeal membrane oxygenation (ECMO). In six of nine neonates surviving ECMO for predictably fatal pulmonary failure, examination 15 to 21 months afterward showed (1) physical growth and development, normal in six; (2) chest x-ray, normal pulmonary parenchyma; (3) average arterial blood gases, PO2 80, Pco2 35, pH 7.35; (4) echocardiogram, normal, without evidence of pulmonary hypertension; (5) cerebrovascular dopplers, normal ophthalmic artery flow in five patients, retrograde in one; (6) CT scan, EEG, neurologic survey, normal in five, cerebral atrophy in one patient who had an air embolus during decannulation; (7) psychologic examination, normal in all. This early evaluation of ECMO survivors should encourage its further application in those newborns who would otherwise die.

High-frequency ventilation at rates of 375 to 1800 cycles per minute in four neonates with congenital diaphragmatic hernia

Neonates with congenital diaphragmatic hernias (CDH) often die because of pulmonary hypoplasia and high pulmonary vascular resistance (PVR). Pulmonary hypertension and right-to-left shunting precedes progressive hypoxia and death. PVR is increased by acidosis and by high airway pressures. High-frequency oscillation (HFO) is a new technique which may improve the outcome for such infants. Gas exchange in HFO is achieved by directing rapid pulsations of small volumes of gas down the trachea, typically at rates greater than 200 cycles per minute, volumes less than 25% of dead space, and low airway pressures. Gas transport results from augmented diffusion, not from bulk flow. Four neonates with CDH deteriorated on conventional mechanical ventilation and required hand ventilation at rates above 200 per minute. HFO at frequencies from 375 to 1800 cycles per minute was then initiated using a flow-interrupter type of oscillator. A marked fall in PaCO2 and a rise in pH resulted. The elimination of CO2 was very efficient with low mean airway pressures (less than 15 mm Hg). The initial improvement during HFO probably resulted from a decrease in PVR due to reversal of the acidosis. However, all four babies died after 13 to 80 hours of HFO. Neonates with CDH who remain hypercapneic despite conventional mechanical ventilation can be successfully ventilated by HFO. Use of HFO produces respiratory alkalosis which may stabilize PVR in the normal range and improve survival rate.

Persistent pulmonary hypertension in the neonate: diagnosis and management

PPHN should be recognized as a clinical condition associated with a number of pulmonary and systemic diseases. Present therapy has resulted in increased survival, but the aggressive methods required to produce improvement necessitate a clear understanding of the underlying pathophysiology in order to minimize sequelae.

Postoperative fetal circulation: POFC

Active pulmonary vasoconstriction and subsequent right-to-left atrial and/or ductal shunting of venous blood may influence the course of many neonatal cardiorespiratory disorders. The term "persistent fetal circulation" has been applied to these infants. This report concerns the late occurrence of fetal circulation after major intraabdominal operative procedures in two neonates. The first patient was a full-term, 3.6-kg infant with a covered, large liver-containing omphalocele. Cyanosis, hypoxia, and a right-to-left shunt were present at birth, but were improved by 24 hr of life. Primary repair was delayed for 6 days, in the belief that fetal circulation was unlikely to recur. On day 7, primary fascial closure of the omphalocele was followed by severe hypoxia secondary to right-to-left shunt, documented to be due to postoperative fetal circulation (POFC). The second was a 1600-g premature infant who was well until noted to be lethargic on the fourth day of life. Radiologic findings of pneumoperitoneum led to laparotomy and closure of a spontaneous gastric perforation. Twenty-four hours later the patient developed severe hypoxia and a right-to-left shunt at the atrial level was documented with contrast echocardiogram, again supporting the diagnosis of POFC. Each patient survived and has a normal heart. Both patients responded to hyperventilation and/or tolazoline therapy. Contrast echocardiography was a helpful, noninvasive means of establishing the diagnosis. This diagnosis should be considered in postoperative neonates after more common cardiac and pulmonary causes of hypoxia are excluded.

Clinical use of an extracorporeal membrane oxygenator in neonatal pulmonary failure

Pulmonary failure is the most frequent cause of mortality in newborns, accounting for 15,000 deaths yearly. It may be the result of the respiratory distress syndrome (RDS), meconium aspiration syndrome (MAS), or persistent fetal circulation (PFC), including infants with congenital diaphragmatic hernia (CDH). Early identification of patients with predictably fatal but potentially reversible respiratory failure refractory to conventional management protocols would permit orderly application of extracorporeal membrane oxygenation (ECMO) as a final resuscitative measure. Eight neonates with severe pulmonary failure manifested by A-a DO2 of greater than 620 torr for greater than 12 hr, persistent cardiovascular instability, and relentless progression of acidosis and hypoxemia were predicted to have a 100% mortality in spite of maximal medical therapy. Four patients presented with MAS and 4 others had PFC, including 2 with CDH. All were supported with ECMO using the internal jugular vein and common carotid artery for access to the right atrium and aortic arch. Following support for 77-313 hr, 6 were successfully weaned from ECMO and then from the ventilator. In these few patients the use of extracorporeal membrane oxygenation after exhaustion of standard therapy was accomplished safely and successfully without untoward short-term sequelae. Extracorporeal ventilatory support may purchase the critical time necessary for resolution of the underlying parenchymal disease, including the pulmonary hypertension associated with CDH.

The management of neonatal posterolateral diaphragmatic hernia

Between March, 1978, and August, 1980, 7 neonates with a left posterolateral diaphragmatic hernia were seen in respiratory distress within 12 hours of birth. Each had severe acidosis and hypoxia. They were immediately intubated and ventilated. Arterial and central venous lines were inserted, the acidosis was partially corrected, and a dopamine infusion of 5 microgram/kg/min was begun immediately. Continuous monitoring of arterial and venous pressures, core, and skin temperatures, blood gases, and pH was instituted. Diaphragmatic defects were repaired by direct suture in 5 neonates and by Gore-Tex patches in the other 2. The left lung in all patients was hypoplastic. Ventilation and inotropic support were continued for 4 to 5 days post-operatively, and close control of acid-base balance was maintained. All the patients are doing well. We consider the key to survival to be management of the dangerous combination of acidosis (by enhancing peripheral and renal perfusion with dopamine) and hypoxia (by prolonged assisted ventilation).

Tolazoline therapy for persistent pulmonary hypertension after congenital diaphragmatic hernia repair

To determine whether vasodilators are useful in persistent pulmonary hypertension associated with congenital diaphragmatic hernia, we reviewed the clinical course, laboratory data, and outcome of 37 patients with respiratory distress and diaphragmatic hernia requiring an operation before 24 hours of life. These patients were divided into two groups, Group I (n = 17) included patients treated prior to the use of tolazoline; Group II (n = 20) included those treated after tolazoline became available. Postoperative severe respiratory distress was observed in ten patients in Group I, and all died. In Group II, 16 patients had severe postoperative respiratory distress and four survived; 12 of these 16 patients received tolazoline, including all four survivors. Treated survivors had significantly higher increase in Pao2 after a test dose of tolazoline than did nonsurvivors. A transient "honeymoon period" of adequate oxygenation correlated with good response to tolazoline, and the presence of both was predictive of survival. No patient survived with the combination of no "honeymoon period" and no response to tolazoline, whereas response to tolazoline without a honeymoon period was sometimes followed by survival. All nonsurvivors had severe lung hypoplasia at autopsy.

Pediatric diaphragmatic hernias. An 11 year experience

A retrospective study of 36 infants and children with diaphragmatic hernia was carried out. Mortality was confined to the group of patients identified between birth and 6 hours of life. Survivors appeared to be separable early in life from those who died on the basis of clinical status at birth measured by the Apgar, by ventilatory capacity of the lung reflected by carbon dioxide pressure and by acid base balance. Oxygenation, time from birth surgery, maternal factors, and labor and delivery appeared to play no role in survival. Hypoplasia of the lung reflected in low lung weights in those who died did not correlate with initial clinical status or blood gas data. Surgical adjuncts to reduction and closure of the hernia did not appear to have an effect on survival. Definition of patients at high risk of dying will permit critical application an evaluation of modes of treatment beyond those now used regularly in the care of these desperately ill infants.

Diagnosis and management of postoperative pulmonary hypertensive crisis

In this paper we discuss two infants and one child who experienced a previously unreported complication after complete correction of a large, unrestrictive ventricular septal defect. Two patients had documented pulmonary hypertensive crises and severe right-heart failure secondary to hypoxia and pulmonary vasoconstriction. These crises were associated with significantly increased right ventricular (RV) peak systolic and end-diastolic pressures and right-to-left shunting via a foramen ovale which, in turn, exaggerated the hypoxis. The crises were treated successfully with tolazoline in the second and third patients. RV pressure returned to normal values and have remained normal up to 12 months postoperatively in the second patient. Although the RV pressures decreased with tolazoline in the third patient, they never reached normal values. Postoperative monitoring of pulmonary artery and RV pressures in infants with large ventricular septal defects is essential when unexplained complications are encountered. Tolazoline proved to be very effective in the treatment of two patients with pulmonary vasoconstriction secondary to hypoxia.