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Abstract

During invasive mechanical ventilation due to the dryness of medical gases is necessary to provide an adequate level of conditioning. The hot water humidifiers (HWH) heat the water, thus allowing the water vapor to heat and humidify the medical gases. In the common HWH there is a contact between the medical gases and the sterile water, thus increasing the risk of patient's colonization and infection. Recently to avoid the condensation in the inspiratory limb of the ventilator circuit, new heated ventilator circuits have been developed. In this in vitro study we evaluated the efficiency (absolute/relative humidity) of three HWH: (1) a common HWH without a heated ventilator circuit (MR 730, Fisher&Paykel, New Zeland), (2) the same HWH with a heated ventilator circuit (Mallinckrodt Dar, Italy) and (3) a new HWH (DAR HC 2000, Mallinkckrodt Dar, Italy) with a heated ventilator circuit in which the water vapor reaches the medical gases through a gorotex membrane, avoiding any direct contact between the water and gases. At a temperature of 35°C and 37°C the HWH and heated tube were evaluated.The absolute humidity (AH) and relative humidity (RH) were measured by a psychometric method. The minute ventilation, tidal volume respiratory rate and oxygen fraction were: 5.8 ± 0.1 l/min, 740 ± 258 ml, 7.5 ± 2.6 bpm and 100%, respectively. Ventilator settings were maintained constant for all the study period. The measurements were taken after 60 min of continuous use.At 35°C the output of the MR 730 with a heated tube was insufficient to provide adequate levels of conditioning, while at 37°C all the three devices were satisfactory. Airway techniques for percutaneous tracheostomy include the LMA, the Combitube, the Microlaryngeal tube and the Perforated Airway Exchanger. Routine bronchoscopy is deemed unnecessary by many, including intensivists in Cardiff. Our audit database stores patient characteristics, techniques and complications, in 700 tracheostomies.A bougie was used during 46. This technique does not use bronchoscopic control. A bougie is passed through the tracheal tube (TT) into the trachea. The TT is withdrawn until the cuff is above the vocal cords. With the cuff fully inflated, the TT is advanced (using the bougie as a guide) until the cuff impacts on the vocal cords. A gas- Critical Care March 2004 Vol 8 Suppl 1 24th International Symposium on Intensive Care and Emergency Medicineseal is maintained by gentle pressure on the TT keeping the cuff pressing on the vocal cords. During percutaneous tracheostomy the bougie remains in the trachea. When ventilation through the tracheostomy tube (cuff inflated) is confirmed, the TT and bougie are withdrawn. Throughout the procedure, if ventilation difficulties occur, the TT can be easily re-inserted using the bougie as a guide.Results Three different bougies were used: types (number used) were Eschmann (29), size 10 Portex disposable (four) and size 12 Portex disposable (13). Three patients were trauma cases: a neutral cervical position was maintained. In 33 cases the Blue ...