Chapter 37: Mobilization and Portable Ventilation

Introduction

In recent years, there has been increasing interest in mobilization and ambulation of mechanically ventilated patients. This therapy requires the use of a portable ventilator. Portable ventilators are also used for intra- and inter-hospital transport. This chapter covers aspects of mobilization and ambulation of mechanically ventilated patients, as well as the use of portable ventilators for transport.

Mobilization

Survivors of critical illness who have been mechanically ventilated can have muscle wasting and fatigue. Survivors of acute respiratory distress syndrome (ARDS) may have persistent physical disability for years after ICU (intensive care unit) discharge. The consequences of these acquired deficits may lead to disability, social isolation, institutionalization, and a significant economic burden for society. A variety of factors are responsible for these physical deficits, including severity of illness, acute inflammation, corticosteroid administration, and use of neuromuscular blockers. Perhaps the most important risk factor is prolonged bed rest.

Daily awakening and spontaneous breathing trials lead to fewer ventilator days, and there is accumulating evidence supporting early physical activity for mechanically ventilated patients. The ABCDE bundle is an evidence-based organizational approach for the management of critically ill mechanically ventilated patients: awakening and breathing coordination of daily sedation and spontaneous breathing trials, choice of sedative or analgesic agents, delirium monitoring, and early mobility and exercise.

Approaches to Mobilization and Ambulation of the Mechanically Ventilated Patient

Prior to ambulation, there are specific factors that need to be considered. It is important to consider the amount of sedation the patient is receiving. In addition to having a more alert and responsive patient, less sedation also frequently allows the patient to be extubated sooner. The patient also needs to be hemodynamically stable. While it may be tempting to move quickly to full ambulation, patients should be allowed to progress more slowly, first sitting up and dangling their legs from the bed, then standing and then taking a few steps at the bedside and moving into a chair before progressing to more ambitious goals.

When considering mobilizing and ambulating patients who are mechanically ventilated, it is important to remember that with respiratory compromise, the patient's ventilatory status and reserve can limit their exercise capacity. This means that, in some cases, respiratory support may need to be increased in order to improve the patient's ability to mobilize and ambulate. Also, because exercise demands an increase in oxygen requirement of the respiratory muscles, it can steal oxygen from other skeletal muscles, causing additional limitation of mobility and ambulation. This effect can be addressed by increasing the amount of support during mobility and ambulation, to allow increased ventilation without increased oxygen demand by the respiratory muscles.