Persistent Pulmonary Hypertension of the Newborn Alison Stoeri Graduate Student GSU Division of Respiratory Therapy

Definition PPHN is defined as systemic arterial hypoxemia inferior to elevated PVR with subsequent shunting of pulmonary blood flow to the systemic circulation. PPHN is a common condition affecting approximately one in every 500 newborns (Davidson et al, 1999) Survivors frequently suffer from cognitive delays, hearing loss, and frequent rehospitalization, with a mortality rate up to 20% (Jankov et al, 2005).

How it happens. . . In the uterus, the infants’ blood sidesteps the lungs Once the infant is born, the blood pressure in the lungs should fall and an increased blood flow to the lungs should occur The blood would then be pumped to the heart and back out to the body

How cont. The ductus arteriosus and foramen ovale then constrict and permanently close in the first day of life. However, in newborns with PPHN, the pressure in the lungs remains high and the ductus arterious and/or foramen ovale remain open, allowing blood to be directed away from the lungs causing hypoxemia.

http://www.persistent-pulmonary-hypertension-newborn.com/index.html

Types of PPHN Abnormally constricted pulmonary vasculature which is the most common type, includes diagnoses such as meconium aspiration syndrome, respiratory distress syndrome, and sepsis Structurally abnormal vasculature, which is often termed idiopathic PPHN Hypoplastic vasculature such as is seen in congenital diaphragmatic hernia, or alveolar capillary dysplasia, a rare malformation of lung development. Seminars in Perinatology

Why does this happen? UNKNOWN however many factors seem to contribute to it such as: Stress while the baby is in the uterus such as maternal diabetes, maternal high blood pressure, maternal anemia, or delivery after 40 weeks. Other causes can be congenital issues stemming from hypoglycemia, meconium aspiration syndrome, infection, anemia, severe pneumonia, and birth asphyxia. The risk for PPHN was 7 times higher after cesarean section deliveries than after vaginal deliveries (Hernandez-Diaz et al, 2007).

More why’s In mothers who take high dose aspirin near term (Perkin et al, 1980). Modifications in vasoactive intermediary levels (Steinhorn et al, 1995). Selective serotonin reuptake inhibitors taken while pregnant. Other factors associated with an elevated risk were maternal black or Asian race, high pre-pregnancy BMI, and asthma (Hernandez-Diaz et al, 2007). http://www.youtube.com/watch?v=krKQNhdOdIE

Signs and Symptoms Tachypnea Tachycardia Nasal flaring and grunting Cyanosis Heart murmurs Low PaO2

Differential Diagnosis Differential diagnoses are Infections, congenital heart diseases, polycythemia, hypothermia, hypoglycemia, hypocalcemia and hypomagnesemia Because of this, many tests can be done to determine if the infant has PPHN

Diagnosis Gold standard is echocardiogram To determine the direction of blood flow in the heart and lungs CXR to rule out congenital defects ABG’s

Diagnosis cont. Pre-ductal (right hand) and post-ductal (right or left foot) pulse oximetry to detect right to left shunting in the ductus arteriosus A difference >10% is positive for PPHN (UCSF, 2004). CBC with serum electrolytes Lumbar puncture, cranial ultrasound, and rarely cardiac catheterization

Treatment Recognizing the existence and severity is the hardest part. The goal of treatment is to reduce PVR through pulmonary vasodilation therapy. The initial step in correcting PPHN is supplemental oxygen through intubation and mechanical ventilation. Overexpansion must be avoided as this may elevate PVR and exaggerate right-to-left shunting.

Treatment cont Nitric Oxide ECMO Mechanical Ventilation Flolan, Viagra and Cialis ECMO http://www.youtube.com/watch?v=c9Zf3BkpAzE Mechanical Ventilation HFOV

PPHN case study 38 week old newborn delivered via c-section and large for gestational age (LGA) Presented with cyanosis, significant respiratory distress including tachypnea, retractions, nasal flaring and poor oxygenation. SpO2 remained <85% on 100% oxygen with ambu bag.

PPHN case study The infant was intubated and given surfactant. CXR showed RDS suggesting PPHN Initial vent settings were: Pressure control rate of 40, PIP of 26, FiO2 1.0, and PEEP of 5. ABG read pH 7.43, PCO2 37, and PaO2 58.

PPHN case study The patient deteriorated over the next 4 hours so the vent was adjusted to Rate 60, PIP 36, FiO2 1.0, and PEEP of 5. ABH read pH 7.34, PCO2 44, and PaO2 46. The CXR showed no improvement

PPHN case study Due to high PIPs with little oxygenation improvement the patient was put on high frequency oscillation (HFO) MAP titrated to reach SpO2 of 100% pH 7.42, PCO2 40, and PaO2 94 The CXR showed adequate inflation and over the next 2 days, the MAP was weaned from an initial 25 down to 14 cmH2O.

PPHN case study The infant was put back on conventional ventilation with settings: SIMV rate 40, PIP 25, FiO2 0.30, PS 8, and PEEP 5. ABG showed hyperventilation SIMV changed over the next day to rate 15, PIP 19, FiO2 0.21, PS 8 and PEEP 5. CXR looked normal, compliance was improved and the infant was successfully extubated.

References Davidson MD, Dennis et al. (1999, August). Safety of withdrawing inhaled nitric oxide therapy in persistent pulmonary hypertension of the newborn. The Official Journal of the American Academy of Pediatrics. Vol. 104 No 2. 231-236. Farrow, K, Filman P, & Steinhorn R. (2005, February). The diseases treated with ECMO: Focus on PPHN. Seminars in Perinatology. Vol. 29. Issue 1. 8-14. George, T.N., et al. The effect of inhaled nitric oxide therapy on bleeding time and platelet aggregation in neonates. The Journal of Pediatrics. Vol. 132. 731-734. Hernandez-Diaz, Sonia, Jan Marter, Linda J. et al. (2007, August). Risk factors for persistent pulmonary hypertension of the newborn. The Journal of Pediatrics. Vol. 120, No 2. 272-282. http://www.persistent-pulmonary-hypertension-newborn.com/index.html http://www.dhmc.org/webpage.cfm?site_id=2&org_id=116&morg_id=0&sec_id=0&gsec_id=3103&item_id=7908 Jankov MB, Robert P, et al. (2005, September). Inhaled nitric oxide therapy for persistent pulmonary hypertension of the newborn: When is it enough? The Journal of Critical Care. Vol 20, Issue 3. 288-293.

References contd Kinsella MD, John P, et al. (2006, July 27). Early inhaled nitric oxide therapy in premature newborns with respiratory failure. The New England Journal of Medicine. Vol 355, No 4: 354-364. Malinski, Tadeusz. (2007). The vital role of nitric oxide. Oakland University Journal. 47-57. Perkin, RM, Levin, DL et al. (1980). Serum salicylate levels and right-to-left ductus shunts in newborn infants with persistent pulmonary hypertension. Journal of Pediatrics. Vol 96. 721-726. Persistent pulmonary hypertension of the newborn (PPHN). (2004). UCSF Children’s Hospital Intensive Care Nursery House Staff Manual. Retrieved March 1, 2008, from http://www.ucsfhealth.org/childrens/health_professionals/manuals/27_PersPulmHyper.pdf. Skimming, J.W., et al. (1997). Nitric oxide inhalation in infants with respiratory distress syndrome. The Journal of Pediatrics. Vol 130: 225-230. Steinhorn, RH, Millard, SL et al. (1995). Persistent pulmonary hypertension of the newborn role of nitric oxide and endothelia in pathophysiology and treatment. Clinics in Perinatology. Vol 22. 405-428. Tanaka, Yuko, et al. (2007, June). Inhaled nitric oxide therapy decreases the risk of cerebral palsy in preterm infants with persistent pulmonary hypertension of the newborn. The Official Journal of the American Academy of Pediatrics. Vol 119, No 6: 1159-1164.