Today, Dr. Rahul Damania, Dr. Pradip Kamat, and their guest, Dr. Jordan Dent, discuss a critical case involving a 15-year-old male who collapsed during football practice due to exertional heat stroke. The discussion emphasizes the clinical presentation, risk factors, pathophysiology, and evidence-based management of heat stroke and other heat-related illnesses in pediatric patients. The episode also delves into the role of rapid cooling interventions and long-term care to minimize mortality and morbidity.

Case Summary: A 15-year-old male with ADHD collapsed during football practice on a hot, humid day. He presented with:

• Normotension (BP: 101/67 mmHg)
• Tachycardia (HR: 157 bpm)
• Tachypnea (RR: 40 breaths/min)
• Febrile (Rectal temp: 41.8°C/107.2°F)
• Dry, hot skin, GCS of 9
• Lab abnormalities: hyponatremia, hypokalemia, hypoglycemia, elevated creatinine, liver enzymes, lactate, CK, and troponin

After suffering cardiac arrest and undergoing resuscitation, the patient developed multiorgan dysfunction, including seizures, encephalopathy, and cerebral edema. Despite severe initial complications, the patient demonstrated neurological improvement with left-side hemiparesis before discharge.

Key Discussion Points:

1. Etiology and Pathophysiology of Heat Stroke:

• Heat stroke occurs when the body’s thermoregulatory mechanisms fail, leading to dangerous elevations in core body temperature. Exertional heat stroke is common during strenuous physical activity in hot, humid environments.
• Key physiological breakdowns include inadequate sweating, vasodilation dysfunction, and subsequent cellular damage due to hyperthermia.

1. Risk Factors for Exertional Heat Stroke:

• Environmental factors: High temperature, humidity, lack of hydration, and breaks.
• Athlete-related factors: Hypohidrosis, dehydration, medical conditions, and medications (e.g., Adderall).
• Heat illness is the third leading cause of death in high school athletics, with American football players particularly at risk.

1. Spectrum of Heat-Related Illness:

• Heat Cramps: Involuntary muscle contractions due to dehydration and electrolyte imbalance.
• Heat Syncope: Transient loss of consciousness due to heat exposure.
• Heat Exhaustion: Milder heat illness with core temperature < 104°F, potentially progressing to heat stroke if untreated.

Welcome to PICU Doc On Call, a podcast dedicated to current and aspiring pediatric intensivists. I'm Dr. Pradip Kamat from Children’s Healthcare of Atlanta/Emory University School of Medicine, and I’m Dr. Rahul Damania from Cleveland Clinic Children’s Hospital. We are two Pediatric ICU physicians passionate about medical education in the PICU. This podcast focuses on interesting PICU cases and their management in the acute care pediatric setting.

In today’s episode, we are excited to welcome Dr. Karen Zimowski, Assistant Professor of Pediatrics at Emory University School of Medicine and a practicing pediatric hematologist at Children’s Healthcare of Atlanta at the Aflac Blood & Cancer Center. Dr. Zimowski specializes in pediatric bleeding and clotting disorders.

A 16-year-old female with a complex medical history, including autoimmune thyroiditis and prior cerebral infarcts, was admitted to the PICU with acute chest pain and difficulty breathing. Despite being on low-dose aspirin, her oxygen saturation was 86% on room air. A CT angiography revealed a pulmonary embolism (PE) in the left lower lobe and signs of right heart strain. The patient was hemodynamically stable, and thrombolytic therapy was deferred in favor of anticoagulation. She was placed on BiPAP to improve her respiratory status. Her social history was negative for smoking, illicit drug use, or oral contraceptive use.

• Diagnosis: Pulmonary embolism (PE)
• Hemodynamics: Stable with no right ventricular (RV) strain on echocardiogram
• Management Focus: Anticoagulation and consultation with the hematology/thrombosis team

• Pathophysiology: Venous thromboembolism (VTE) in children involves components of Virchow’s triad: stasis of blood flow, endothelial injury, and hypercoagulability.
• Incidence: VTE is rare in the general pediatric population but increases significantly in hospitalized children.
• Age Distribution: Bimodal peaks in infants and adolescents aged 15-17 years.
• Risk Factors: Central venous lines, infections, congenital heart disease, cancer, and autoimmune disorders.

• Symptoms: Swelling, pain, warmth, and skin discoloration in the affected extremity.
• Specific Presentations:
• SVC syndrome from superior vena cava thrombosis
• Abdominal pain from portal vein thrombosis
• Hematuria from renal vein thrombosis
• Neurological symptoms...

Welcome to PICU Doc On Call, where Dr. Pradip Kamat from Children’s Healthcare of Atlanta/Emory University School of Medicine and Dr. Rahul Damania from Cleveland Clinic Children’s Hospital delve into the intricacies of Pediatric Intensive Care Medicine. In this special episode of PICU Doc on Call shorts, we dissect the Alveolar Gas Equation—a fundamental concept in respiratory physiology with significant clinical relevance.

Key Concepts Covered:

• Alveolar Gas Equation Demystified: Dr. Rahul explains the Alveolar Gas Equation, which calculates the partial pressure of oxygen in the alveoli (PAO2). This equation, PAO2 = FiO2 (Patm - PH2O) - (PaCO2/R), is essential in understanding hypoxemia and the dynamics of gas exchange in the lungs.
• Calculating PAO2: Using the Alveolar Gas Equation, the hosts demonstrate how to calculate PAO2 at sea level, emphasizing the influence of atmospheric pressure, fraction of inspired oxygen (FiO2), water vapor pressure, arterial carbon dioxide pressure (PaCO2), and respiratory quotient (R) on oxygenation.
• A-a Gradient and Hypoxemia: The A-a gradient, derived from the Alveolar Gas Equation, is discussed in the context of hypoxemia evaluation. Understanding the causes of hypoxemia, including ventilation/perfusion (V/Q) mismatch, anatomical shunt, diffusion defects, and hypoventilation, is crucial for clinical diagnosis and management.
• Clinical Scenarios and A-a Gradient Interpretation: Through a clinical scenario, the hosts elucidate how different conditions affect the A-a gradient and oxygenation, providing insights into respiratory pathophysiology and differential diagnosis.
• Clinical Implications and Management Strategies: The hosts highlight the clinical significance of the Alveolar Gas Equation in assessing oxygenation status, diagnosing gas exchange abnormalities, and tailoring respiratory management strategies in the pediatric intensive care setting.

Key Takeaways:

• Utility of the Alveolar Gas Equation: Understanding and applying the Alveolar Gas Equation is essential for evaluating oxygenation and diagnosing respiratory abnormalities.
• Interpreting A-a Gradient: A normal A-a gradient suggests alveolar hypoventilation as the likely cause of hypoxemia, whereas elevated gradients indicate other underlying pathologies.
• Clinical Relevance: Recognizing the clinical implications of the Alveolar Gas Equation aids in accurate diagnosis and optimal management of respiratory conditions in pediatric intensive care patients.

Conclusion:

Join Dr. Kamat and Dr. Damania as they unravel the complexities of the Alveolar Gas Equation, providing valuable insights into respiratory physiology and its clinical applications. Don’t forget to subscribe, share your feedback, and visit picudoconcall.org for more educational content and resources.

References:

• Fuhrman & Zimmerman - Textbook of Pediatric Critical Care Chapter: Physiology of the respiratory system. Chapter 42. Khemani et al. Pages 470-481
• Rogers textbook of Pediatric intensive care: Chapter 44....