Heat and moisture exchangers versus heated humidifiers for mechanically ventilated adults and children.

BACKGROUND: Invasive ventilation is used to assist or replace breathing when a person is unable to breathe adequately on their own. Because the upper airway is bypassed during mechanical ventilation, the respiratory system is no longer able to warm and moisten inhaled gases, potentially causing additional breathing problems in people who already require assisted breathing. To prevent these problems, gases are artificially warmed and humidified. There are two main forms of humidification, heat and moisture exchangers (HME) or heated humidifiers (HH). Both are associated with potential benefits and advantages but it is unclear whether HME or HH are more effective in preventing some of the negative outcomes associated with mechanical ventilation. This review was originally published in 2010 and updated in 2017. OBJECTIVES: To assess whether heat and moisture exchangers or heated humidifiers are more effective in preventing complications in people receiving invasive mechanical ventilation and to identify whether the age group of participants, length of humidification, type of HME, and ventilation delivered through a tracheostomy had an effect on these findings. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase and CINAHL up to May 2017 to identify randomized controlled trials (RCTs) and reference lists of included studies and relevant reviews. There were no language limitations. SELECTION CRITERIA: We included RCTs comparing HMEs to HHs in adults and children receiving invasive ventilation. We included randomized cross-over studies. DATA COLLECTION AND ANALYSIS: We assessed the quality of each study and extracted the relevant data. Where possible, we analysed data through meta-analysis. For dichotomous outcomes, we calculated the risk ratio (RR) and 95% confidence interval (95% CI). For continuous outcomes, we calculated the mean difference (MD) and 95% CI or standardized mean difference (SMD) and 95% CI for parallel studies. For cross-over trials, we calculated the MD and 95% CI using correlation estimates to correct for paired analyses. We aimed to conduct subgroup analyses based on the age group of participants, how long they received humidification, type of HME and whether ventilation was delivered through a tracheostomy. We also conducted sensitivity analysis to identify whether the quality of trials had an effect on meta-analytic findings. MAIN RESULTS: We included 34 trials with 2848 participants; 26 studies were parallel-group design (2725 participants) and eight used a cross-over design (123 participants). Only three included studies reported data for infants or children. Two further studies (76 participants) are awaiting classification.There was no overall statistical difference in artificial airway occlusion (RR 1.59, 95% CI 0.60 to 4.19; participants = 2171; studies = 15; I2 = 54%), mortality (RR 1.03, 95% CI 0.89 to 1.20; participants = 1951; studies = 12; I2 = 0%) or pneumonia (RR 0.93, 95% CI 0.73 to 1.19; participants = 2251; studies = 13; I2 = 27%). There was some evidence that hydrophobic HMEs may reduce the risk of pneumonia compared to HHs (RR 0.48, 95% CI 0.28 to 0.82; participants = 469; studies = 3; I2 = 0%)..The overall GRADE quality of evidence was low. Although the overall methodological risk of bias was generally unclear for selection and detection bias and low risk for follow-up, the selection of study participants who were considered suitable for HME and in some studies removing participants from the HME group made the findings of this review difficult to generalize. AUTHORS' CONCLUSIONS: The available evidence suggests no difference between HMEs and HHs on the primary outcomes of airway blockages, pneumonia and mortality. However, the overall low quality of this evidence makes it difficult to be confident about these findings. Further research is needed to compare HMEs to HHs, particularly in paediatric and neonatal populations, but research is also needed to more effectively compare different types of HME to each other as well as different types of HH.

Comparison between bougies and stylets for simulated tracheal intubation with the C-MAC D-blade videolaryngoscope.

BACKGROUND: The C-MAC D-blade is a new, highly angulated, videolaryngoscope blade designed for use in patients with difficult airways. Directing a tracheal tube into the trachea with any indirect viewing laryngoscope can be difficult, even with a good view of the laryngeal inlet. OBJECTIVE: To determine which introducing strategy is most suitable for use with the C-MAC D-blade videolaryngoscope. DESIGN: Observational manikin study. SETTING: Centre for Simulation and Patient Safety. PARTICIPANTS: Twenty-four anaesthetists of at least 12 months' of experience. INTERVENTIONS: Six tracheal tube introducer strategies (no tracheal tube introducer (TX); hockey stick stylet (SH); Gliderite stylet (SG); bougie with tube loaded distally, near its curved tip (BD); bougie with tube loaded proximally (BP); bougie unloaded until tracheal placement (BU)) for each of two laryngoscopy settings (easy and difficult) in a SimMan 3G manikin. Two intubation attempts, with a maximum time allowance of 60 s each, were allowed for all laryngoscopy setting/introducer combinations. MAIN OUTCOME MEASURES: Time to intubate in seconds. Secondary outcome was overall subjective difficulty using a visual analogue scale. RESULTS: In the easy laryngoscopy setting, time to intubation was [median (interquartile range): SH 8.5 sec (7 to 11); SG 10 (8 to 11.5); BD 11 (10 to 12.5); TX 11 (7 to 31.5); BP 12 (11 to 13.5); BU 13 (11 to 14.5). There was no evidence of an overall difference in introducer strategies for time to intubate (P <  .025) with SG and SH found to be favourable when compared with BU, and SH was also favourable when compared with BP. In the difficult laryngoscopy setting, time to intubation was: SG 11.5 (10 to 17.5); SH 14 (12 to 22); BD 15.5 (12 to 23.5); BU 16.5 (14 to 21); BP 16.5 (15.5 to 20.5); TX 60 (26.5 to 60). There was evidence of an overall difference in introducer strategies for time to intubate (P < 0.025) with all introducers found to be favourable compared with TX. SG was found to be favourable when compared with BU and BP. In groups TX and SH, anaesthetists failed to intubate in 13 of 24 cases and 1 of 24 cases, respectively. The visual analogue scores tended to reflect intubation times, more so in the difficult setting. CONCLUSION: The differences in time to intubate in both the easy and difficult laryngoscopy settings were minor for the different introducer strategies studied. The stylet introducers tended to take less time, but this did not result in important statistical differences. When using the C-MAC D-blade videolaryngoscope for simulated tracheal intubation, stylets and bougies performed in a similar fashion.

Inappropriate prescribing of proton pump inhibitors in primary care.

OBJECTIVES: To determine if an educational intervention initiated in secondary care can influence prescribing of proton pump inhibitors (PPIs) in the community. METHODS: A prospective study of PPI use in patients admitted to medical wards in a university hospital. A simple educational intervention was employed to reduce inappropriate prescribing of PPIs in the community. RESULTS: In the pre-intervention analysis 66/271 (24%) patients were receiving treatment with a PPI prescribed in the community. In 36/66 (54%) patients the PPI had been prescribed inappropriately. Six months after the intervention 91/344 (26%) patients were prescribed a PPI in the community. In only 45 of these 91 (49%) patients was there a recommended indication. CONCLUSION: The intervention used in this study had no effect on the proportion of patients taking a PPI at the time of hospital admission or on the appropriateness of prescribing in the community.