CDH Teaching 2024

Please read below case so that we can initiate the small group discussion. This will be complemented by TNE views that will trigger other points of discussions such as:

• Implications of fetal markers of severity

• Implications of the atrial and ductal shunting pattern

• Evaluation of RV and LV function 

• Shifting phenotypes during the course of CDH transition / first post-natal days

• Cardiovascular and respiratory management, alongside integrative strategies affecting the cardio-respiratory system such as nutrition, fluid balance, sedation, analgesia, and the timing of surgical interventions, form the cornerstone of a comprehensive management approach. At the core of this strategy is the optimization of the cardio-pulmonary setup, crucial for effective treatment and patient stability (no pun intended).

Case

Julia is a patient prenatally diagnosed with a left-sided Congenital Diaphragmatic Hernia (CDH). She was born prematurely at 35 weeks. The pregnancy was complicated by polyhydramnios. Her fetal assessment outlined: observed-to-expected lung-to-head ratio (O/E LHR) at 22% and fetal MRI showing 20% of the predicted lung volume. Fetal echocardiography suspected aortic arch hypoplasia, a non-apex forming left ventricle, and right (RV) to left ventricular (LV) discrepancy, without clear evidence of mitral or aortic stenosis. Her liver and stomach were displaced into the chest cavity. Amniocentesis was performed and chromosomal Microarray (CMA) testing confirmed that there were no identified genetic abnormalities on this particular investigation. Family declined FETO due to their concern of prematurity related to the procedure.

Julia was delivered spontaneously vaginally, with a highly prepared medical team present in the delivery room to manage her immediate needs. Following delivery, Julia was intubated in the delivery room and an orogastric tube was placed for gastric decompression. Her heart rate remained above 100 bpm at all times, and she exhibited reactive behavior right from birth. There was no delayed cord clamping performed. Her Apgar scores were 6 at one minute, improving slightly to 7 at five and ten minutes.

She was admitted to the Neonatal Intensive Care Unit (NICU). In the NICU, she was placed on conventional mechanical ventilation with a volume guarantee of 4.5 mL/kg, PEEP of 5, and a respiratory rate of 40, with peak inspiratory pressures ranging between 23-25 (MAP generated of 9). Double lumen umbilical venous line (UVL) and single lumen umbilical arterial line (UAL) were secured, with central positioning as confirmed by chest radiography. The radiograph also confirmed the presence of bowel loops occupying the left chest field.

Initial assessments in the NICU revealed a preductal oxygen saturation of 92% and a postductal saturation of 67%.  FiO2 was 55%, to aim pre-ductal saturation 85-95%. Blood gas analysis from the UAL showed a PaO2 of 38 mmHg, a CO2 of 45 mmHg, and a pH of 7.28, bicarbonate of 20.4. Julia's bedside team expressed concerns about her prolonged capillary refill time of around 4 seconds and the weakness of pulses both pre and postductally. Her blood pressure measured at 36/29 mmHg (mean of 32) via UAL, with non-invasive readings from the right arm closely mirroring these figures at 35/26 mmHg. The first lactate measurement was elevated at 3.5. NIRS was installed and cerebral reading is 48% and somatic reading ("renal") is 32%. 

Orient your readings with these question in mind: 

• Calculate oxygen index - click here.

• What would be your assessment of the prenatal parameters?

• What is the evidence regarding FETO for moderate? or severe CDH?

• Upon a TNE evaluation, what would be the potential phenotypes that you would anticipate?

• Is the duct currently open? What would be the expected directionality if so, and what could be the reasons?

• Would you suspect a coarctation - why or why not?

• When and for which reason would you consider: iNO, prostacyclins and/or PGE.

• What would be your management if there is: left ventricular dysfunction? right ventricular dysfunction? biventricular dysfunction?

• What would the inter-atrial shunting pattern infom you on?

  • Why would it be right to left?

  • Why would it be left to right?

  • Why would it be bidirectional?

• What are other management considerations: 

  • Sedation/Analgesia

  • Nutrition

  • Fluid management / transfusions

  • Timing of repair

  • ECMO

Hemodynamics of Congenital Diaphragmatic Hernia - June 2024