Effects of electrical muscle stimulation physical functional outcomes in patients receiving prolonged mechanical ventilation

Summary

Patients receiving mechanical ventilation (breathing support) in intensive care, rapidly lose profound amounts of limb muscle. This markedly affects subsequent physical function and long-term quality of life. Muscle wasting is difficult to prevent, and during the early stages of critical illness, patients may be too unstable to participate in usual forms of rehabilitation. Electrical muscle stimulation (EMS) is a technique which exercises muscle by sending electrical current to muscles through skin electrodes. It prevents muscle wasting, and in other patient groups improves strength and functional ability. EMS can be applied early and safely after intensive care unit (ICU) admission, and therefore may be a useful treatment when patients are unstable. We are currently investigating the use of EMS in patients receiving mechanical ventilation in a study called E-vent, at the Bristol Royal Infirmary ICU, and will be using the results to inform a further full scale trial grant application. We are asking for a further 10 months funding, to allow recruitment of 8 more patients in order to complete the study, and to provide backfill time for data analysis, writing up and completion of a full scale trial NIHR grant application.

Project completed July 2014 with full recruitment. In write up for publication.

Main findings

1. The recruitment strategy enrolled the target sample - patients received mechanical ventilation for a mean of 9.69 (6.27) days and were in ICU for 14.39 (6.60) days.
2. Significant muscle wasting was demonstrated in the intervention (p=0.007) and control (p=0.016) groups as quantified by ultrasound measures of rectus femoris and quadriceps. A trend to greater Rfcsa wasting was evident in the EMS group.
3. EMS did not prevent muscle wasting, preserve muscle strength, or confer any functional benefit at ICU discharge
4. 64% (n=165) of planned EMS treatments were delivered. EMS is more difficult to deliver twice a day than once a day in the ICU population.
5. Hospital LOS was significantly longer in the EMS group (p=0.027). The reasons for this are no clear.
6. Urinary 3MH was significantly higher in the EMS group (p=0.026) at ICU discharge suggesting EMS may have induced muscle damage.
7. Rectus Femoris Cross sectional area was the most useful outcome measure with the effect size at ICU discharge of 0.41 along with urinary 3MH at 0.63

Impact

EMS may not be appropriate for early stages of critical illness, and does not impact muscle strength or function in critically ill patients receiving prolonged periods of ventilation. These findings add to a small body of evidence which has found EMS detrimental. This has important implications for physiotherapy in the early stages of critical illness, since EMS was considered a potentially useful adjunct during the period of time when formal treatment impossible.

Outputs

Abstracts submitted and accepted for conferences; Intensive Care Society Conference December 2012, local symposiums at UHBT October 2012, May 2013, Birmingham Respiratory Care Conference 2012, preliminary results presented SICOWE January 2015

Further funding applications

None.