From the Guidelines
Infants with cystic fibrosis are at a higher risk of heat-related illness due to impaired sweat gland function, which leads to excessive salt loss and electrolyte imbalances, particularly sodium and chloride depletion. This condition is exacerbated by the fact that breast milk and standard infant formula have relatively low sodium content, making it difficult for infants with CF to maintain adequate sodium levels, especially in hot environmental conditions 1. The underlying mechanism involves the CFTR gene mutation, which affects chloride channel function in sweat gland cells, preventing normal reabsorption of salt from sweat before it reaches the skin surface.
When exposed to hot environments, infants with CF sweat more but cannot properly regulate their body temperature due to the salt imbalance, leading to dehydration, heat intolerance, and potentially dangerous electrolyte imbalances. To mitigate this risk, parents should ensure their infants with CF stay hydrated with appropriate electrolyte solutions, avoid excessive heat exposure, dress them in lightweight clothing during hot weather, and provide salt supplementation as prescribed by their physician (typically 1/8 to 1/4 teaspoon of salt added to their formula or food daily).
Key considerations for managing heat-related illness in infants with CF include:
- Monitoring for signs of dehydration and electrolyte imbalances, such as excessive thirst, dark urine, and decreased urine output
- Providing frequent breaks in cool, well-ventilated areas to reduce heat exposure
- Avoiding strenuous activities during peak heat hours
- Using lightweight, light-colored clothing to reflect the sun's rays and allow for good airflow
- Seeking medical attention immediately if symptoms of heat-related illness occur, such as fever, vomiting, or seizures. According to a study on global climate change and children's health, infants younger than 1 year are at particularly increased risk of heat-related illness and death 1.
From the Research
Impaired Sweat Gland Function in Cystic Fibrosis
- Infants with Cystic Fibrosis (CF) suffer from higher rates of heat-related illness due to impaired sweat gland function, which leads to excessive dehydration and electrolyte imbalances 2.
- The high salt content of CF patients' sweat and the consequent absence of body-fluid hyperosmolality during a long episode of sweating may deprive such patients of a thirst stimulus, resulting in inadequate fluid intake 3.
Heat Intolerance and Dehydration
- CF patients may underestimate their fluid needs and undergo excessive dehydration during extended exposure to hot conditions, which can increase morbidity and mortality 3.
- The addition of flavor, carbohydrate, and NaCl to water can increase voluntary drink intake in healthy children, but CF patients may require a higher NaCl concentration to prevent voluntary dehydration 4.
Electrolyte Imbalances and Metabolic Alkalosis
- Infants with CF are at risk of developing hypoelectrolytemia and metabolic alkalosis due to chronic loss of sweat electrolytes, which can be exacerbated by mild gastrointestinal or respiratory illness 2.
- Heat acclimation can improve sweat gland function and lower sweat sodium concentration in adults with CF, but further research is needed to determine its benefits for infants and children 5.
Heat Acclimation and Sweat Gland Function
- CF patients can heat acclimate, which can reduce peak rectal temperature and heart rate, but their sweat chloride and sodium concentrations remain significantly higher than those of normal controls 6.
- Heat acclimation can increase sweat loss and sweat gland activity, while decreasing sweat sodium concentration, which may help reduce the risk of heat-related illness in CF patients 5.