Differences in the degree of respiratory and peripheral muscle impairment are evident on clinical, electrophysiological and biopsy testing in critically ill adults: a qualitative systematic review.

BACKGROUND

Critically ill patients are exposed to a combination of insults that affect both respiratory and peripheral skeletal muscle function. However, different muscle groups may not be affected to the same extent by a prolonged critical illness.

OBJECTIVE

To review original observational studies that measured an aspect of respiratory and peripheral muscle function in adults in the intensive care setting.

DESIGN

Systematic review strategy and qualitative data synthesis.

DATA SOURCES AND REVIEW

METHODS

Four major citation databases were searched. Search terms included intensive care, critical care, diaphragm, quadriceps, and skeletal, respiratory and limb muscle. Titles and abstracts were reviewed to identify studies that measured both respiratory and peripheral muscle function. Reference lists of suitable publications were screened. Studies sampling critically ill patients with a neurological condition were excluded.

RESULTS

1119 items were identified, and 19 full-text/ abstract publications were reviewed. Ten studies investigated patients with a critical illness-related neuromuscular disorder. Nine studies targeted septic patients with multiple organ failure or patients requiring prolonged mechanical ventilation. Clinical, electrophysiological and muscle biopsy specimen data were collected at different time-points and milestones relating to alertness, weaning criteria, respiratory support reduction and extubation.

CONCLUSIONS

Currently available bedside methods of measuring respiratory and peripheral muscle function in critically ill patients are somewhat inadequate. Yet there is evidence suggesting that respiratory muscles may be relatively spared from the damage that can occur as a result of immobility, prolonged mechanical ventilation and systemic inflammation in critical illness.