July 2014

Dr John Andrzejowski, Sheffield.  1. Does Prone Positioning Increase Intracranial Pressure? A Retrospective Analysis of Patients with Acute Brain Injury and Acute Respiratory Failure. Neurocrit Care. 2014 Jul 2. [Epub ahead of print] Roth C1Ferbert ADeinsberger W, et al Studies looking at ICP changes and prone position have been contradictory. In this study the authors studied patients with ICP monitoring who had to be turned prone for a variety of (respiratory mainly) indications. A post hoc analysis was carried out on the 29 patients with ICP monitoring who were treated with prone positioning (PP) from 2007 to 2013 in a German intensive care unit. Prone positioning was performed in a 135° position (ie not fully proned; the head was rotated so venous drainage could have been compromised) for 8 h per treatment unit for an average of 2.5 days per patient. The mean baseline ICP in supine patients was 9.5 ± 5.9 mmHg and was increased significantly to 15.4 ± 6.2 mmHg during PP. (p < 0.0001). I was surprised to read that there was no significant difference between CPP in supine position vs PP (82 vs 80 mmHg) despite MAP in these patients decreasing from 73 to 65 mmHg in the prone position. The low baseline ICP still does not address the question of how individual patients with high ICP would tolerate PP. The authors state however that ICP values >20 mmHg occurred more often during PP than SP and were associated with significantly more episodes of decreased CPP <70 mmHg. The main positive finding that the authors feel justifies proning sick patients with potential intracerebral pathology is the fact that mean paO2/FiO2 ratio (P/F ratio) was increased significantly in PP. ‘Our study shows a moderate, yet significant elevation of ICP during prone positioning. However, the achieved increase of oxygenation by far exceeded the changes in ICP’. Prone positioning is not to be undertaken lightly in neuro patients since clinical monitoring (eg pupils etc) is very difficult. I suspect that patients with higher ICP to start with will be more affected although the study does not look a this. Patients who may need PP should have ICP monitoring inserted if there is a chance that CPP may affect outcome.

  1. Laryngeal mask airway versus endotracheal tube for percutaneous dilatational tracheostomy in critically ill adult patients.

Strametz R, Pachler C, Kramer JF, et al. Cochrane Database of Systematic Reviews 2014, Issue 6. I found this recent review after a colleague raised an eyebrow when I said I wanted to use an LMA to facilitate a percutaneus dilatational tracheostomy (PDT) in a patient who had gone off on the NITU. They were starved and had an easy airway. This Cochrane review looked at the safety and effectiveness of Endotracheal tube (ETT) versus Laryngeal mask (LMA) in critically ill adult patients undergoing PDT on the ICU. Eight RCTs involving 467 participants were included. All studies had between 40 and 73 participants This review addresses the following research questions:

  1. Is an LMA more effective than an ETT in terms of procedure-related or all-cause mortality?

Only one study reported the number of people who died, and the results were too uncertain for researchers to determine how use of ETT or LMA affected mortality. No procedure-related death was reported for any intervention.

  1. Is an LMA safer than an ETT in terms of procedure-related life-threatening complications during a PDT procedure?

Some studies showed that fewer adverse events occurred when ETT was used and some reported fewer adverse events in the LMA group. Overall, neither method was superior in terms of preventing adverse events. The tally of participants in included studies with adverse events ranged from 0% to 33% in the LMA group and from 0% to 50% in the ETT group

  1. Does use of an LMA influence the conditions for performing a tracheostomy (e.g. duration of procedure)?

Use of LMA seems to shorten the duration of the procedure with improved visibility conditions for the physician, and this shortens the period during which the airway is insecure. (mean difference -1.46 minutes, 95% CI -1.92 to -1.01 minutes, 324 participants, P value _ 0.00001, low-quality evidence). There were no differences in fatal loss of airway, desaturation or post procedural pneumonia or aspiration. It seems like both techniques have complications and that LMA is no worse although the authors urged caution due to the low numbers and poor data. Studies focusing on late complications and relevant patient-related outcomes are necessary for definitive conclusions on safety issues related to this procedure.