TITLE:
Feasibility of bioelectric impedance as a measure of muscle mass in mechanically ventilated ICU patients
AUTHORS:
Linda L. Chlan
KEYWORDS:
Mechanical Ventilation; Bioimpedance; Muscle Mass; ICU-Acquired Weakness
JOURNAL NAME:
Open Journal of Nursing,
Vol.4 No.1,
January
22,
2014
ABSTRACT: Background: Critically ill patients receiving prolonged
mechanical ventilatory support are at risk for loss of muscle mass and muscle
strength from immobility. Feasible, non-invasive methods are needed to accurately
obtain data on markers of muscle mass to design effective interventions and
monitor patient progress during recovery from
critical illness. Bioelectric impedance has been used in other settings to
obtain data on body composition and muscle mass. Purpose: The aims of this
study were to determine the feasibility of bioelectric impedance as a marker
of muscle mass in a sample of mechanically ventilated patients and to assess
data trends in these obtained values. Methods: A descriptive design was used to
obtain standard bioelectric impedance
parameters (total body resistance,
legs resistance, and percent lean body mass) over 4 days from eligible
patients already enrolled in a randomized clinical trial. Results: Bioimpedance
parameters were readily obtained over 4 days in a sample of 43 patients (age 59
+ 15.7 years, 56% male) receiving prolonged ventilatory support (mean 9.4 +
10.4 days) due to respiratory failure. Reasons for not obtaining impedance
measures included skin impairment, monitoring devices, or presence of implantable cardiac defibrillator or pacemaker. Average total body impedance was 464.3 + 117.1 ohms, while average impedance of legs
was 479.1 + 146.4 ohms. Lean body mass was 68.4% (+10.8).
Conclusions/Implications for Practice: With carefully trained staff and a standardized measurement protocol, bioimpedance is a feasible method to obtain body
composition data reflective of muscle mass in mechanically ventilated patients.
Further research will determine the utility of bioimpedance to monitor recovery
and effectiveness of interventions to restore function after prolonged periods
of ventilatory support and immobility in mechanically ventilated patients.