Renal function changes and seasonal temperature in patients undergoing cardiac surgery

Area of Science:

• Nephrology
• Cardiology
• Environmental Medicine

Background:

• Previous observations suggest seasonal variations in serum creatinine (SC) and estimated glomerular filtration rate (eGFR) in humans and mammals.
• The impact of temperature-dependent seasonal changes on kidney function markers and acute kidney injury (AKI) in cardiac surgery patients remains unclear.

Purpose of the Study:

• To investigate seasonal fluctuations in SC and eGFR among cardiac surgery patients.
• To determine if these seasonal changes correlate with variations in postoperative AKI incidence.

Main Methods:

• Retrospective analysis of 16,023 adult cardiac surgery patients from 2000-2012.
• Assessment of baseline and postoperative SC and eGFR values based on the month of surgery.
• Correlation analysis with meteorological data (temperature, humidity, wind speed).

Main Results:

• Patients operated during warmer months (May-October) exhibited significantly higher baseline and peak postoperative SC levels compared to colder months.
• Estimated glomerular filtration rate (eGFR) showed a similar seasonal pattern, decreasing in warmer months.
• Despite higher SC and lower eGFR in warmer seasons, the overall postoperative AKI rate was not significantly different, although a trend towards higher AKI in August was noted.

Conclusions:

• Cardiac surgery patients experience higher serum creatinine and lower eGFR during the warmest season, irrespective of AKI incidence.
• Potential contributing factors include dehydration, anemia, and increased transfusion rates during warmer periods.
• Further research is warranted to elucidate the mechanisms behind these observed seasonal kidney function variations.