Abstract
Background: The use of heated ventilator circuits (HVC) is common practice in a majority of hospitals. HVCs are designed to maintain inhaled gas at body temperature pressure saturated (BTPS) and reduce rain out for optimal patient comfort. HVC temperature can be variable based on the room temperature and other supplies utilized near the ventilator circuit. Patients can experience burns at 44 degrees Celsius (109.4°F)1. In our Pediatric Intensive Care Unit (PICU), a 12 kg patient sustained burns from a HVC while undergoing a bedside surgical procedure. We aimed to create a bench model to validate this scenario and ensure all methods for patient safety while using HVCs are considered. Methods: A Gettinge Servo-i ventilator was set up with a Fisher & Paykel 202 infant circuit to simulate a spontaneously breathing patient. A Fisher & Paykel (MR850) heater was integrated with the HVC and ventilator. A standard Hill-Rom patient bed was utilized, and the HVC was draped across to the middle of the bed where a patient would be positioned. Control temperatures were obtained with the HVC exposed to room air (69.6°F). Scenarios were benched with a standard hospital grade blanket, forced air patient heater, and surgical drape placed over the HVC. Temperatures were obtained with a Fluke Infrared 561 Thermometer at four locations along the HVC. The temperature of the circuit was measured from a distance of 5 inches. Bench scenarios were repeated three times. Results: The temperature range of the HVC was 34.61 – 52.14°C with an average of 42.88°C in all models. The simulated blanket model produced the highest temperatures. Measurements at 20 cm and 30 cm from the patient produced the highest temperature readings. See graph for detailed results. Conclusions: In our bench model temperatures within the HVC rose to 52.14°C in specific scenarios. While the heater temperature at the humidifier and temperature probe remained within specifications, the circuit temperature rose well above safe limits. Other bedside supplies may be a necessity but the HVC location should be a vital concern to avoid patient harm. Warning labels to highlight this potential harm should be included with HVCs so that bedside clinicians can be aware of the risks. Reference: 1. Evers L, Vhavsar D, Mailander P. The biology of burn injury. Exp Dermatology 2010;19(9):777-783. doi:10.1111/j.1600-0625.2010.01105.x.
This graph displays the recorded temperatures in the inspiratory circuit in the bench model with a blanket drapped over the HVC.
Footnotes
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