Lung protective ventilation

Published Date: 19th July 2016

Publication Authors: Angus W, Glennon K, Mahambrey T, Miller T

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INTRODUCTION

In 2013 Futier et al. published work showing that a lung protective ventilation strategy with low tidal volumes for patients undergoing elective major abdominal surgery was associated with improved clinical outcome and reduced healthcare utilisation. It is established within intensive care that protective ventilation strategies are best practice, however until Futier et al's work, this had not been investigated in anaesthetised patients.

OBJECTIVES

To conduct an audit to investigate tidal volume (Vt) usage in patients anaesthetised for elective major abdominal surgery within our hospital. Audit standards were taken from Futier et al's work with target tidal volume to be between 6-8mls/Kg IBW (ideal body weight).

METHODS

A retrospective audit was conducted over a 4-month period from Sep 2013-Jan 2014 inclusive. Data was extracted from an electronic document management system. Inclusion criteria were open or laparoscopic abdominal surgery of duration equal to or greater than 2 h and age over 18. Patients were excluded if BMI (body mass index)>35, sepsis or mechanical ventilation within preceding 2 weeks or if they had undergone emergency surgery i.e. non-elective. IBW was calculated using calculation from ARDSnet2.

RESULTS

63 patients were included, 35 male and 28 female. Mean BMI was 26.28. Mean recorded Vt was 514mls. 58.7 % of patients had ventilatory Vt within a range of 6-8mls/Kg of ABW (73 % below 8mls/Kg ABW in total), but only 28.6 % had a Vt of 6-8mls/Kg of IBW. Overall, patients were ventilated at a mean of 1.36mls/kg above an upper limit of 8mls/Kg IBW.

CONCLUSION

Post-operative respiratory complications have significant consequences for both the patient and the hospital system, which is under ever increasing pressure. As clinicians we have a responsibility to reduce where possible any foreseeable complications associated with general anaesthesia, especially pertinent as part of an enhanced recovery programme and in the prevention of unplanned intensive care admissions. In contrast to the original study we included adult patients below 40 years of age as we felt that protective ventilation represents best practice that should be applicable to all, barring other specific exceptions. It was shown that in our institution, using ABW the majority of patients are ventilated within a target range of 6-8mls/Kg but this is significantly reduced against IBW. A protocol for ventilation in major abdominal surgery will be implemented in line with the provision to all theatres of a conversion chart for ABW to IBW, following which the audit will be repeated to close the cycle. Lest we forget, Primum non nocrere.

Miller, T; Angus, W; Mahambrey, T; Glennon, K; Sim, K. (2014).  Lung protective ventilation in elective major abdominal surgery - an audit . Intensive Care Medicine. 40 (Supplement 1), S235

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