M Thió1, R Bhatia, J A Dawson, P G Davis. 1. Neonatal Service, University Hospital Sant Joan de Déu, Barcelona, Spain. mthio@hsjdbcn.org
Abstract
BACKGROUND: Guidelines recommend avoidance of excessive oxygen administration during neonatal resuscitation. Blenders are used in some but not all hospitals. It has been suggested that self-inflating bags without a reservoir deliver around 40% oxygen and could be used to provide an inexpensive and effective technique of avoiding oxygen toxicity. OBJECTIVE: To explore how much oxygen is delivered when using two different brands of neonatal self-inflating resuscitation bags without a reservoir. METHODS: In a benchtop setting, the smallest non-disposable self-inflating bags from the Laerdal and Ambu ranges were tested. Oxygen concentration delivered by these devices under a variety of conditions was measured. 108 combinations of oxygen flow rates (10; 5 to 1 litre/min), ventilation rates (30, 60, 100 inflations/min) and peak inspiratory pressure ranges (20 to 25 cm H(2)O, 35 to 40 cm H(2)O or pop-off valve range, 55 to 60 cm H(2)O) were tested. RESULTS: Delivered oxygen concentration varied depending on three parameters: gas flow rate, ventilatory rate and pressure. At a pressure of 20 to 25 cm H(2)O, mean oxygen concentration delivered by both bags exceeded 70% at any gas flow rate except for 1 litre/min (where delivered oxygen concentration was 60% to 70%). When the pop-off valve was opened at 35 to 40 cm H(2)0, oxygen concentrations fell to 30% to 45% at gas flow rates < or =2 litres/min. The Ambu bag delivered a lower oxygen concentration than the Laerdal bag but this difference was not clinically important. CONCLUSION: When using the Laerdal and Ambu infant resuscitation self-inflating bags without a reservoir, delivered oxygen concentration is >70% for currently recommended flow and pressure settings.
BACKGROUND: Guidelines recommend avoidance of excessive oxygen administration during neonatal resuscitation. Blenders are used in some but not all hospitals. It has been suggested that self-inflating bags without a reservoir deliver around 40% oxygen and could be used to provide an inexpensive and effective technique of avoiding oxygentoxicity. OBJECTIVE: To explore how much oxygen is delivered when using two different brands of neonatal self-inflating resuscitation bags without a reservoir. METHODS: In a benchtop setting, the smallest non-disposable self-inflating bags from the Laerdal and Ambu ranges were tested. Oxygen concentration delivered by these devices under a variety of conditions was measured. 108 combinations of oxygen flow rates (10; 5 to 1 litre/min), ventilation rates (30, 60, 100 inflations/min) and peak inspiratory pressure ranges (20 to 25 cm H(2)O, 35 to 40 cm H(2)O or pop-off valve range, 55 to 60 cm H(2)O) were tested. RESULTS: Delivered oxygen concentration varied depending on three parameters: gas flow rate, ventilatory rate and pressure. At a pressure of 20 to 25 cm H(2)O, mean oxygen concentration delivered by both bags exceeded 70% at any gas flow rate except for 1 litre/min (where delivered oxygen concentration was 60% to 70%). When the pop-off valve was opened at 35 to 40 cm H(2)0, oxygen concentrations fell to 30% to 45% at gas flow rates < or =2 litres/min. The Ambu bag delivered a lower oxygen concentration than the Laerdal bag but this difference was not clinically important. CONCLUSION: When using the Laerdal and Ambu infant resuscitation self-inflating bags without a reservoir, delivered oxygen concentration is >70% for currently recommended flow and pressure settings.