Learning objectives

• Describe congenital diaphragmatic hernia
• Understand the predictors for survival in congenital diaphragmatic hernia
• Management of congenital diaphragmatic hernia

Definition and mechanisms

• Congenital diaphragmatic hernia (CDH) is a birth defect characterized by the development of a hole in the diaphragm, leading to the protrusion of abdominal contents into the thoracic cavity affecting the normal development of the lungs
• 90% is left-sided
• Infants born with CDH experience respiratory failure due to pulmonary hypertension and pulmonary hypoplasia (decreased lung volume)
• Newborns born with CDH require immediate care at delivery → delivery should be as close to term as possible
• CDH is a life-threatening condition → death occurs due to
  • Inadequate gas exchange surface
  • Fixed high pulmonary vascular resistance (decreased vascular cross-sectional area, normal cardiac output)
  • Reversible pulmonary hypertension
  • Pneumothorax
  • Additional anomalies (5%) and complications of intensive therapy

Diagnosis and survival

• CDH is usually discovered during a routine prenatal ultrasound
• The stomach, intestines, or liver may be present in the fetus’ chest where the lungs should be; the fetus’ heart may also be pushed to one side by the extra organs in the chest

Antenatal ultrasound predictors of survival in CDH

• Calculate the lung-to-head ratio (LHR) by dividing the fetal lung area (mm2) by the fetal head circumference (mm)
  • LHR >1.35: 100% survival
  • LHR 1.35 to 0.6: 61% survival
  • LHR <0.6: No survival
• Calculate the observed to expected LHR (O/E LHR) by dividing the observed LHR by the expected ratio for gestational age
  • The fetal lung area increases 16-fold compared to a 4-fold increase in the head circumference between 12 and 32 weeks of gestation
  • O/E LHR <25%: Severe CDH (survival 10% with liver up and 25% with liver down)
  • O/E LHR <15% with liver up: No survival
• Position of the liver (or presence of liver herniation)
  • Liver herniation with LHR <1.0: 60% mortality
  • Liver in the thorax: 56% survival

Anesthetic considerations

• Emergency situation
• Critically ill neonate
• Hypoplastic lungs
  • Respiratory insufficiency (hypoxemia, hypercarbia, acidosis)
  • Permissive hypercarbia may be required
  • Consider HVO or ECMO
• Pulmonary hypertension
  • Potential for right ventricle failure, reduced cardiac output
  • Consider inhaled NO
• Transitional circulation
  • Potential for right-left and left-right shunting
  • Patent ductus arteriosus
• Delayed surgical repair, resuscitation is first priority
• NICU required

Management

Resuscitation

• Call NICU
• Indication for immediate tracheal intubation to facilitate intermittent positive pressure ventilation (IPPV)
• No bag-mask ventilation → distends herniated viscera, worsens mediastinal shift, and increases the risk of pneumothorax; while barotrauma further damages the hypoplastic lungs
• Nasal intubation helps with fixation and ventilator compliance
• Pass a nasogastric tube to deflate the gut and keep on free drainage
• Umbilical artery/vein lines
• ABG, chest X-ray, echocardiogram
• Lung protective ventilation
  • Target SaO2 >85% and permissive hypercapnia (PaCO2 <65 mmHg, pH >7.25)
  • PCV or PSV PIP <25 cmH2O
  • Inspiratory time 0.35 sec
  • PEEP 3-5 mmHg
  • RR <65
  • Consider HVO, iNO, or ECMO
• Consider NO and inotropes for pulmonary hypertension
• Fluid: Target MAP 45-50 mmHg
• Sedation: Opioids and benzodiazepines, thoracic epidural
• Avoid neuromuscular blocking drugs

Keep in mind

• Immediate management at birth includes bowel decompression, avoidance of mask ventilation, and endotracheal tube placement if required
• The main focus of management includes gentle ventilation, hemodynamic monitoring, and treatment of pulmonary hypertension, followed by surgery

Suggested reading

• Leininger K, Chiu K. Anesthetic Considerations In Congenital Diaphragmatic Hernia. [Updated 2022 Nov 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572077/ 
• Pollard BJ, Kitchen G. Handbook of Clinical Anaesthesia. 4th ed. Taylor & Francis group; 2018. Chapter 24 Paediatrics, Lomas B.
• Chandrasekharan PK, Rawat M, Madappa R, Rothstein DH, Lakshminrusimha S. Congenital Diaphragmatic hernia – a review. Matern Health Neonatol Perinatol. 2017;3:6.