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Byline: Sayed. Ali, Anthony. Ochola, Fatimah. Juma, Feroza. DaroowallaSir,Brain death, with a functioning cardiovascular system, remains a difficult issue to grasp for most families. Furthermore, conversations about brain death remain [...]

OBJECTIVE: To determine potential effects of humidification on the volume of airway secretions in mechanically ventilated patients. METHODS: Water vapor delivery from devices providing non-heated-wire humidification, heated-wire humidification, and heat and moisture exchanger (HME) were quantified on the bench. Then, patients requiring 24-hour mechanical ventilation were exposed sequentially to each of these humidification devices, and secretions were removed and measured by suctioning every hour during the last 4 hours of the 24-hour study period. RESULTS: In vitro water vapor delivery was greater using non-heated-wire humidification, compared to heated-wire humidification and HME. In vivo, a total of 9 patients were studied. Secretion volume following humidification by non-heated-wire humidification was significantly greater than for heated- wire humidification and HME (P = .004). CONCLUSIONS: The volume of secretions appeared to be linked to humidification, as greater water vapor delivery measured in vitro was associated with greater secretion volume in vivo. [ABSTRACT FROM AUTHOR]

BACKGROUND: Practitioners often presume there is adequate humidification in the ventilator circuit if the Y-piece is at a specified temperature, but control of Y-piece temperature may be inadequate to ensure adequate humidification. METHODS: In an in vitro bench model we measured water-vapor delivery with several heated humidification setups and a wide range of minute volume ((...)E) values. The setup included a condenser, hygrometry, and thermometer. First, we calibrated the system with a point-source humidifier and water pump. Then we tested the watervapor delivery during non-heated-wire humidification and during heated-wire humidification with a temperature gradient of +3°C, 0°C, and -3°C between the humidifier and the Y-piece. We compared the results to 2 recommended humidification values: 100% saturated (absolute humidity 44 mg H2O/L) gas at 37°C (saturated/37°C); and 75% saturated (absolute humidity 33 mg H2O/L), which is the humidity recommended by the International Organization for Standardization (the ISO standard). In all the experiments the setup was set to provide 35°C at the Y-piece. RESULTS: Our method for measuring water-vapor delivery closely approximated the amount delivered by a calibrated pump, but slightly underestimated the water-vapor delivery in all the experiments and the whole (...)E range. At all (...)E values, water-vapor delivery during non-heated-wire humidification matched or exceeded saturated/37°C and was significantly greater than that during heated-wire humidification. During heated-wire humidification, water-vapor delivery varied with the temperature gradient and did not reach saturated/37°C at (...)E > 6 L/min. Water-vapor delivery with the negative temperature gradient was below the ISO standard. CONCLUSIONS: Maintaining temperature at one point in the inspiratory circuit (eg, Y-piece), does not ensure adequate water-vapor delivery. Other factors (humidification system, (...)E, gradient setting) are critical. At a given temperature, humidification may be significantly higher or lower than expected. [ABSTRACT FROM AUTHOR]