Neonates will continue to receive care in the neonatal intensive care unit (NICU), which will be medically optimized before repairing the diaphragmatic hernia. Neonates are intubated at birth, ventilated mechanically, and decompressed via an oro- or nasogastric tube set to low continuous suction. Deliveries can be performed either as spontaneous vaginal or cesarean sections. Maternal mean arterial pressure (MAP) should be maintained within 20% of baseline to ensure adequate uteroplacental blood flow.ĭelivery is planned for 37 to 39 weeks at a tertiary center with extracorporeal membrane oxygenation (ECMO) capabilities. It should be obtained intraoperatively if there is any concern for fetal deterioration. As this procedure will involve significant stress on the fetus, it is routine to measure fetal heart rate by Doppler ultrasound before and after the operation. Anesthesia for the fetus involves an ultrasound-guided intramuscular injection of fentanyl, rocuronium, and atropine to achieve analgesia and paralysis while mitigating fetal bradycardia. Maternal anesthesia can be achieved either with local, spinal-epidural, or general anesthesia, depending on the patient's clinical situation and comfort level. Results from the European Tracheal Occlusion to Accelerate Lung Growth (TOTAL) and Fetal Endoscopic Tracheal Occlusion (FETO) clinical trials are currently pending. FETO is currently considered experimental, although initial case studies showed increased survival rates after undergoing FETO. The occlusion is best removed at least one day before birth to allow for the repopulation of type II pneumocytes, given that tracheal occlusion has been found to reduce these cell numbers.
The occlusion may also be taken down at birth using the ex-utero intrapartum treatment (EXIT) procedure to provide a bridge to intubation. This occlusion is performed around 27 to 29 weeks and is often removed by 34 weeks through ultrasound-guided balloon puncture or fetal tracheoscopic takedown and retrieval. During development, blockage of the normal egression of lung fluid will increase transpulmonic pressures, helping the fetal lung expand against the herniated viscera. The procedure involves the percutaneous placement of a balloon in the fetal trachea to prevent the expulsion of pulmonary fluid. It is generally only performed on fetuses with severe CDH based on observed-to-expected lung-to-head ratio (O/E LHR) scoring and the presence of liver herniation.
The only prenatal invasive intervention is fetal endoluminal tracheal occlusion (FETO). Intestinal malrotation and congenital heart disease are commonly seen in this patient population CNS, renal, and esophageal abnormalities are rarer but may also occur. Īdditional physiologic concerns may be brought to light upon further evaluation with fetal MRI or echocardiography. The combination of significant PH and residual fetal circulatory elements may lead to severe hypoxemia refractory to conventional treatments, a condition known as persistent pulmonary hypertension of the newborn (PPHN). By contrast, the right side of the heart is more often found to have hypertrophy due to the elevated pulmonary pressures and increased PFO shunting, leading to increases in both afterload and preload, respectively.
Additionally, compressive forces may cause cardiac rotation, favoring blood flow through a patent foramen ovale (PFO), further exacerbating the shunt, and decreasing LV preload. One likely cause of LV hypoplasia is decreased LV filling pressures due to right-to-left shunting via a patent ductus arteriosus (PDA) in the setting of pulmonary hypertension. LV hypoplasia with associated poor LV function is not an uncommon finding. The compressive forces of the herniation also can alter cardiac physiology significantly. PH results from hypertrophy of pulmonary vasculature and increased vasoreactivity and is exacerbated by the elevated arterial carbon dioxide (PaCO2) levels and decreased oxygen (PaO2) levels associated with inefficient gas exchange. Abdominal viscera compressing the developing lungs interferes with the branching of pulmonary airways and vasculature, leading to pulmonary hypoplasia and vascular remodeling. The underdeveloped lungs are characterized by poor gas exchange caused primarily by thickened alveolar walls and diminished functional surface area secondary to decreased bronchiolar terminal branching, acinar hypoplasia, and dysfunctional surfactant production. Neonates with congenital diaphragmatic hernia have several critical differences in cardiopulmonary physiology, most notably being poor gas exchange, left ventricular (LV) hypoplasia, right ventricular (RV) hypertrophy, and pulmonary HTN (PH).
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