2025 – PAGE 434 – PULMONOLOGY

HYPERCAPNIA (AKA HYPERCAPNEA)

Hypercapnia (AKA hypercapnea) refers to an elevated CO2, not a fast respiratory rate. Can result in agitation, flushing of the skin, and even headaches (cerebral vasodilation).

PEARL: Opioids cause a central apnea resulting in hypercapnia (elevated CO2), but since oxygenation is ok, the O2 sats or PO2 may be normal.

BRIEF RESOLVED UNEXPLAINED EVENT (BRUE)

This diagnosis was formerly called an “acute life-threatening event” (ALTE). A “brief resolved unexplained event” (BRUE) is an event observed in a child < 1 year old for < 1 minute in which one or more criteria are met. The criteria include cyanosis, pallor, irregular or absent breathing, change in muscle tone (hyper- or hypotonia) and altered responsiveness. Do a detailed history and physical exam in order to rule out other possible causes. Further workup is pursued if a specific disorder is suspected. BRUE is a diagnosed of exclusion. For a low-risk child, admission is not required. Offer the family CPR training and community resources. Consider a 12-lead EKG, pertussis testing, and spot-checking oxygen with pulse oximetry. There is no need in most cases for additional testing or prescription medications. However, if “warning signs” are present, then hospitalize the child. Warning signs include anything that suggests a pathologic cause, such as lethargy, vomiting, respiratory distress, a history of sustained cyanosis, the need for CPR during the event, bruising, syndromic features, prior BRUEs and unexplained death in a sibling.

PEARL: Infant must be well appearing and back to baseline at the time of presentation to qualify as a BRUE.

ALPHA-1-ANTITRYPSIN DEFICIENCY

Alpha-1-antitrypsin deficiency results in lung and liver disease that may not present until adolescence. Emphysema is noted on imaging with bullae at the bases of the lungs. Liver disease can result in ascites, cirrhosis, GI tract varices, portal vein hypertension, splenomegaly, and coagulopathy. A biopsy of the liver will show globules. Labs can show a high GGT and possibly an elevated alkaline phosphatase.

PEARL: Patients may not have any lung symptoms.

MNEMONIC: Bullae are at the Bases, close to the other problematic site, the LIVER!

RESPIRATORY DISTRESS SYNDROME (RDS)

Respiratory distress syndrome (RDS) is caused by a relative surfactant deficiency. Look for a premature baby that did not receive steroids prior to birth. Chest X-ray will show bilateral ground glass findings and air bronchograms. The risk of RDS is significantly HIGHER in an infant of a diabetic mother (IDM) or a baby born by C-section. The risk is LOWER if the child had IUGR, a mother on drugs, prolonged rupture of membranes (PROM), or an LS ratio > 2.0. Intubate the baby if the pH is < 7.2 or pCO2 is > 60. Otherwise, give O2 and shoot for a goal PO2 of 50–70.

PEARL: Consider a patent ductus arteriosus (PDA) if the baby is not getting any better after 2–3 days.

TRANSIENT TACHYPNEA OF THE NEWBORN (TTN)

Transient tachypnea of the newborn (TTN) is caused by leftover fetal alveolar fluid in the lungs after delivery, which leads to pulmonary edema. The onset is typically within 2 hours of delivery. Findings may include tachypnea (RR > 60 breaths/minute), cyanosis, grunting, flaring, retractions, increased AP-P diameter of the chest, and a normal lung exam on auscultation. CXR findings can include hyperinflated lungs, flat diaphragms, mild cardiomegaly, increased vascular markings in a sunburst pattern at the hilum, fluid in the interlobar fissures, and pleural effusions. Treat with supplemental O2 and expect it to resolve in 12-24 hours, though it can take as long as 72 hours.