Mechanical Ventilation: Beyond the ICU

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Mechanical Ventilation: Methods

The method of long-term mechanical ventilation that is best for the patient will be determined by the physician, respiratory therapist, and the patient. A patient capable of some independent activities and several hours a day off the ventilator will have different requirements than the patient who needs ventilator assistance 24 h a day.

Invasive methods use a tracheostomy—a surgical hole in the windpipe through which a tube is channeled to assist breathing.

Noninvasive methods use masks, nasal tubes, and other techniques that do not require surgical entry into the respiratory tract. Some apply positive pressure to the mouth and/or nose. Others apply negative pressure to the chest or body by lowering the pressure outside the body.

All methods of ventilation require an initial assessment of comfort and efficacy and follow-up monitoring of daytime and nighttime breathing. The patient and caregivers should be educated in use and maintenance of the equipment needed to provide the support.

Noninvasive Methods

• Positive Pressure Ventilation: Mouth and/or Nose

Positive pressure ventilation delivers air (and sometimes extra oxygen when medically necessary) to the patient through a face mask, mouthpiece, or nasal mask. Patients who can be independent of the ventilator for portions of the day may use noninvasive positive-pressure ventilation to assist nighttime breathing.

• Negative Pressure Ventilation

Entry of air into the lungs is assisted by applying intermittent negative pressure (like a vacuum) to the chest and abdomen by means of a body tank (iron lung), a chest shell, or a body jacket.

• Rocking Bed

A bed with rocking motion assists ventilation by intermittently causing the diaphragm to move up and down, creating a "pumping" motion in the chest, and thus, helping air to go in and out of the lungs.

• Pneumobelt

An inflatable band around the abdomen presses on the abdomen and forces air in and out of the lungs. The pneumobelt may be used in combination with other noninvasive methods of ventilation. It may not be suitable for some patients—for example, patients who are excessively underweight or overweight. The patient must be sitting up for this device to work. It is often used by patients in a wheelchair.

• Diaphragm Pacing

An electronic pacer stimulates the diaphragm to contract, thus assisting breathing by "bellows" motion of the diaphragm. This method is used by patients who have high (C1-C2) spinal cord injury, and with tracheostomy in some children who cannot breathe spontaneously because of a problem with central control of breathing.

• Glossopharyngeal Breathing

Sometimes called "frog" breathing—a technique in which the patient learns to "gulp" air into the lungs. Some patients use this technique in order to spend more time off the ventilator and to have "free" time in case of ventilator failure.

• Manually Assisted Coughing

A caregiver helps the patient to exhale and clear mucus from the lungs by delivering a thrust similar to a Heimlich maneuver. Thorough training of the patient and caregivers is required to make this technique effective and to avoid injury to the patient.

Invasive Methods

Invasive methods may be needed for patients who are unable to use noninvasive methods. Invasive mechanical ventilation requires a tracheostomy for placement of a tracheostomy tube into the windpipe to deliver air directly into the lungs. The patient and caregivers are trained in care of the tracheostomy and tube to prevent complications such as infection around the tracheostomy tube or clogging of the tube.

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