[size=20px]A 3 kg term newborn with antenatally diagnosed left congenital diaphragmatic hernia (CDH) is hemodynamically stable on conventional mechanical ventilation. Over several hours, the mean arterial pressure falls from the mid 40s to the low 30s, urine output decreases from 2 to 0.5 cc/kg/h and the serum lactate increases from 2mmol/l to 4 mmol/l. A 20 cc/kg normal saline bolus is given, and dopamine is started at 10 ug/kg/min. One hour later, there has been minimal improvement in the blood pressure or urine output, and the oxygenation index (OI) has increased from 12.5 to 30. The next step in management of this CDH infant is:

 

A Repeat 20cc/kg NS bolus

 

B Start inhaled nitric oxide

 

C Increase dopamine infusion to 15ug/kg/min

 

D Cannulate for ECMO

 

E Obtain echocardiogram[/size]

B

E

correct answer

E Obtain echocardiogram

 

The goals of early hemodynamic management of CDH target a normal blood pressure for age, evidence of adequate peripheral perfusion as suggested by a normal urine output and avoidance of lactic acidosis.

 

In the described case, the primary physiologic problem is persistent systemic hypotension despite a fluid bolus and initiation of inotropic support. The rising oxygenation index (OI= mean airway pressure x FiO2/post-ductal pO2) suggests increased right to left shunting, which is most likely due to changes in the pulmonary to systemic pressure gradient at the ductus arteriosus. Therefore, goal-directed hemodynamic management in this infant should urgently identify and address the etiology of the systemic hypotension and increasing right to left shunt shunt.

 

Both the CDH EURO Consortium consensus guidelines and the Canadian CDH Collaborative guidelines recommend a judicious crystalloid bolus (not to exceed 20 cc/kg) as a first step in the management of systemic hypotension. If this does not result in hemodynamic improvement, then initiation of inotropic support according to local practice (often dopamine, dobutamine and/or hydrocortisone) is recommended. If hypotension still persists, then further therapy should be guided by echocardiographic assessment of cardiac filling, right and left ventricular function, ductal patency and shunt with estimates of pulmonary artery pressure. Choice of therapy is guided by volume status, the presence and severity of ventricular dysfunction (right, left or biventricular), severity of pulmonary hypertension and the potential for pharmacologic maintenance of ductal patency (e.g. PGE1) to offload a dilated right ventricle. Follow-up echocardiography would be expected to provide useful assessments of the response to targeted hemodynamic therapy.