Decreasing the number of nurses on duty in an intensive care unit (ICU) increases the risk of serious infection, according to a report published in the open access journal Critical Care.
Stéphane Hugonnet and colleagues from the University of Geneva Hospitals, Switzerland, investigated the number of patients admitted to the ICU who developed ventilator-associated pneumonia (VAP), over a four-year period. They then compared this to the number of nurses on duty for each patient in the preceding days. VAP affected over a fifth of the 936 patients who received mechanical ventilation during the study.
The team found that when there were lower numbers of nurses, patients were more likely to catch pneumonia six days or more after being placed on a ventilator. This suggests that bacteria are transferred between patients, or from one site to another in the same patient. This could be due to short-staffed nurses having less time to follow hand hygiene recommendations and proper isolation procedures or being unable to provide adequate care to the ventilated patient. The nurses' training level had no effect on infection rates.
The authors concluded that this study backs up findings from their earlier general study on ICU infection risks, namely that employing more than two nurses per patient per day would prevent a large proportion of infections. There was an average ratio of two nurses per patient per day in the ICU during this study.
"This study shows that a low nurse-to-patient ratio increases the risk of late-onset VAP," said Hugonnet. "It adds also to the growing body of evidence demonstrating that adequate staffing is a key determinant and a prerequisite for adequate care and patient safety."
VAP is caused by bacteria entering the lungs as a consequence of the ventilator tubing and is one of the most common preventable problem affecting critically ill hospital patients. It can cause a stay of about an average of 10 extra days in hospital at a cost of US$10,000 to $40,000.