Rehabilitation Considerations for Children Dependent on Long-Term Mechanical Ventilation

Table 2

Mechanical ventilation classifications.

Non-invasive
Positive pressure ventilation; Airway pressure applied via face mask or nasal prongs; positive pressure beginning in the upper airway causes gas flow to the lungs until the ventilator breath is terminated; as the airway pressure drops to zero, elastic recoil of the chest accomplishes passive exhalation by pushing the tidal volume out.; Two types: Bi-level Positive Airway Pressure (BiPAP)—provides both inspiratory and expiratory positive airway pressure; Continuous Positive Airway pressure (CPAP)—provides only single level of airway pressure.; Negative pressure ventilation; Delivered via cuirass (shell); vacuum pump creates negative pressure in the chamber, resulting in reduced intrapulmonary pressure and allowing air flow into the lungs and expansion of the chest; when vacuum terminated, negative pressure applied to chest becomes zero, recoil of chest and lungs permits passive exhalation.
Invasive
Positive pressure ventilation; Airway pressure applied through an endotracheal tube or tracheostomy tube; gas flows along pressure gradient between upper airway and alveoli; achieved by delivering either a pre-determined volume or a set pressure to the lungs on a regular or a demand basis; PPV modes defined by inspiratory parameters.; Volume modes: Controlled Mechanical Ventilation (CMV)—100% control by ventilator, patient has minimal or no respiratory effort); Assist Control Ventilation (ACV)—if patient fails to initiate breathing within prescribed time, ventilator triggers breath); Intermittent Mandatory Ventilation (IMV)—combination of spontaneous breathing and CMV as the ventilator provides a positive pressure breath at a pre-determined frequency); Synchronized Intermittent Mandatory Ventilation (SIMV)—patient triggers mandatory breath in assist mode thus synchronizing with own respiratory effort.; Pressure modes: Pressure Support  Ventilation (PSV)—patient-triggered breath with a preset positive pressure thus using patient’s own inspiratory timing and tidal volume; used for weaning; Pressure Control Ventilation (PCV)—time-initiated, pressure-limited and time-cycled mode; intended for patients fully dependent on MV; Pressure Assist Control Ventilation (PACV)—all breaths machine delivered at preset tidal volume; allows for patient triggering of breaths as described with PCV.; Positive End Expiratory Pressure (PEEP)—primary expiratory parameter; can be added to all above modes; used to increase functional residual capacity and distend alveoli.