Congenital Diaphragmatic Hernia

Question 1

What is CDH

Answer 1

A congenital diaphragmatic hernia (CDH) is an early developmental defect that results in the extrusion of intraabdominal organs (ie. stomach, small intestines, kidney, liver) into the thoracic cavity.

Question 2

What are the most common congenital abnormalities associated with CDH

Answer 2

Cardiac

Question 3

Where do CDH occur most commonly

Answer 3

Posterolateral aspect of the diaphragm (75% are on the left)

Also: anterior diaphragmatic hernias ass. with Downs)

Question 4

What are the physiological consequences of CDH

Answer 4

Physiologic consequences of CDH include lung hypoplasia, pulmonary hypertension, and pulmonary arteriolar dysregulation/reactivity

Question 5

Compare the previous treatment strategy for CDH compared to what is done now

Answer 5

Previous treatment strategy
1. Considered a surgical emergency –> straight to theatre

2. Ventilatory strategy: aggressive hyperventilatory strategies with the goal of obtaining pulmonary vasodilation through hyperoxia and respiratory alkalosis.

This strategy often used high peak inspiratory pressures, ventilatory frequency, and oxygen concentration. This tactic was eventually abandoned after further research stressed the harmful effects of large lung inflations in the postnatal period as well as the prominence of iatrogenic chronic lung disease in CDH survivors

Updated treatment startegy
1. Delayed surgery after optimization in ICU until the ventilator support has been minimized, pre- to post-ductal saturation gradient has decreased, and pulmonary hypertension has minimized as suggested by ECHO.

2. Lung protective ventilation: Low Vt with permissive hypercapnea. Boloker, et al. suggested preservation of spontaneous ventilation, acceptance of a pre-ductal oxygen saturation of 90-95% with >80% tolerated if the infant appears comfortable, permissive hypercapnia of 8 kPA mmHg, and peak inspiratory pressures < 25 cm H20.

Question 6

What are the next steps in treatment if there is failure to miinimize ventilator support, reduce preductal-postductal SaO2 gradient and pulmonary hypertension on ECHO?

Answer 6

Inhaled Nitrous Oxide
HFOV (High Flow Oscillatory Ventilation)
ECMO

n patients with refractory pulmonary hypertension, some institutions utilize nitric oxide. However, the effectiveness of this intervention in CDH has not been clearly demonstrated (Bloch, et al. 2007). Further salvage techniques involve high frequency oscillatory ventilation (HFOV) and extracorporeal membrane oxygenation (ECMO). While joint studies between Toronto and Boston have shown no survival benefit between the two interventions, many centers now reserve ECMO for rescue therapy for infants who have failed other means of ventilation (Bohn, 2006).