Do fevers cause insensible volume losses in patients?

From the Guidelines

Fevers do cause increased insensible volume losses in patients. When a patient develops a fever, their metabolic rate increases, leading to greater fluid loss through the skin and respiratory tract. According to the espghan/espen/espr/cspen guidelines on pediatric parenteral nutrition: fluid and electrolytes 1, water requirements increase with fever, hyperventilation, hypermetabolism, and gastrointestinal losses.

• Key points to consider:
  • Insensible water loss from the skin and lungs is an energy costly process that consumes a quarter of the overall caloric expenditure, 0.5 kcal per 1 ml of water lost 1.
  • Fluid requirements can be fulfilled by infusing 100 ml/kg//d (4 ml/kg/h) for every kilogram of body weight < 10 kg plus 50 ml/kg/d (2 ml/kg/h) per kg body weight between 10 and 20 kg plus 25 ml//kg/d (1 ml/kg/h) per kg body weight above 20 kg 1.
  • Water and energy requirements are also decreased during critical illness, mechanical ventilation, and in temperature-controlled environments 1. In clinical practice, this means that febrile patients require additional fluid replacement beyond their baseline needs, taking into account the severity and duration of the fever, as well as individual patient factors such as age, weight, and underlying medical conditions.
• Considerations for fluid management in febrile patients include:
  • Monitoring urine output and osmotic load to assess hydration status and electrolyte balance 1.
  • Adjusting fluid replacement according to disease state and individual patient needs 1.
  • Providing sufficient water supply to meet increased energy needs and prevent dehydration 1.

From the Research

Insensible Volume Losses in Patients with Fever

• Fevers can cause insensible volume losses in patients, as evidenced by increased evaporative water losses from the skin and respiratory tract 2, 3.
• A study published in Acta chirurgica Scandinavica in 1980 found that patients with highly elevated body temperature (above 39.5 degrees C) had increased cutaneous water loss, which was 6-8 times higher than basal values 2.
• Another study published in the same journal in 1981 found that the evaporative water loss from the respiratory tract was significantly increased when patients' temperature rose above 39 degrees C, resulting in an extra loss of about 110 g/24 h 3.
• However, the dermal loss due to sweating was found to be of greater importance, amounting to 500-1000 g/24 h, compared to the respiratory extra loss 3.
• The magnitude of insensible water loss can vary depending on factors such as ambient temperature and humidity, and can be estimated using simplified formulas 4.
• Fever management strategies, including antipyretic therapy, are controversial and may not always be necessary, as fever is a normal adaptive response to infection 5, 6.