The Humidity in a Low-Flow Dräger Fabius Anesthesia Workstation with or without Thermal Insulation or a Heat and Moisture Exchanger: A Prospective Randomized Clinical Trial

Abstract

BackgroundDuring anesthesia, as compared with intensive care, the time of the tracheal intubation is much shorter. An inhaled gas minimum humidity of 20 mgH2O.L-1 is recommended to reduce the deleterious effects of dry gas on the airways during anesthesia with tracheal intubation. The Fabius GS Premium® anesthesia workstation (Dräger Medical, Lübeck, Germany) has a built-in hotplate to heat gases in the breathing circuit. A heat and moisture exchanger (HME) is used to further heat and humidify the inhaled gas. The humidity of the gases in the breathing circuit is influenced by the ambient temperature. We compared the humidity of the inhaled gases from a low-flow Fabius anesthesia workstation with or without thermal insulation (TI) of the breathing circuit and with or without an HME.MethodsWe conducted a prospective randomized trial in 41 adult female patients who underwent elective abdominal surgery. The patients were allocated into four groups according to the devices used to ventilate their lungs using a Dräger Fabius anesthesia workstation with a low gas flow (1 L.min-1): control, with TI, with an HME or with TI and an HME (TIHME). The mean temperature and humidity of the inhaled gases were measured during 2-h after connecting the patients to the breathing circuit.ResultsThe mean inhaled gas temperature and absolute humidity were higher in the HME (29.2±1.3°C; 28.1±2.3 mgH2O·L-1) and TIHME (30.1±1.2°C; 29.4±2.0 mgH2O·L-1) groups compared with the control (27.5±1.0°C; 25.0±1.8 mgH2O·L-1) and TI (27.2±1.1°C; 24.9±1.8 mgH2O·L-1) groups (P = 0.003 and P<0.001, respectively).ConclusionsThe low-flow Fabius GS Premium breathing circuit provides the minimum humidity level of inhaled gases to avoid damage to the tracheobronchial epithelia during anesthesia. TI of the breathing circuit does not increase the humidity of the inhaled gases, whereas inserting an HME increases the moisture of the inhaled gases closer to physiological values.

Related factors of perioperative low body temperature and incidence of postoperative shivering in patients undergoing complex percutaneous nephrolithotomy and the effect analysis of composite insulation nursing intervention

“…Body temperature is a crucial vital sign that must be maintained within a specific range to ensure normal human metabolism. Hypothermia refers to abnormally low body temperature, often resulting from various factors during the perioperative period [ 15 ]. Studies have shown that approximately 50 %–70 % of patients experience varying degrees of hypothermia [ 16 ].…”

Effects of different fresh gas flows and different anesthetics on airway temperature and humidity in surgical patients: a prospective observational study

“…The HME used in anesthesia respiratory circulation keeps the humidity and temperature of the patient’s airway near to the physiological values like low fresh gas flow rate. 7 12 13 14 15 16 17 18 19 There is no consensus on the sufficient temperature and AH of the inspired gas pending mechanical ventilation handling an endotracheal tube. 12 However, anesthesiologists generally determine the rate of fresh gas flow to patients according to their clinical experience, surgical requirements and habits; they do not care whether an HME is used or not.…”

“…IAH values were reported in another study that used a Drager Fabius anesthesia workstation, TIVA anesthesia, and a 1 L/min fresh gas flow. 19 While that study used a 1 L/min fresh gas flow like the study that used a Drager Primus anesthesia workstation, it used TIVA anesthesia instead of isoflurane anesthesia. 18 When these two studies were compared, the values obtained in the HME (–) groups were the same, whereas the values obtained in the HME (+) groups were lower than in the study that used TIVA anesthesia.…”