Aetna considers non-invasive negative pressure ventilation medically necessary durable medical equipment (DME) for members with stable or slowly progressive respiratory failure due to neuromuscular diseases, chest wall deformity, or central hypoventilation syndromes (see background section for selection criteria).

Aetna considers non-invasive negative pressure ventilation experimental and investigational for all other indications (e.g., acute hypoxemic respiratory failure) because its effectiveness for indications other than the ones listed above has not been established.

Note:  Non-invasive negative pressure ventilation may be given to members with respiratory failure with the use of devices that apply intermittent negative extra-thoracic pressure and augment tidal volume.  These include body ventilators and the poncho wrap.

Note: Electrical generators do not meet Aetna’s definition of DME because they are not primarily medical in nature.

Aetna considers a second invasive or non-invasive ventilator medically necessary if it is required to serve a different purpose as determined by the member’s medical needs.  Examples (not all-inclusive) of situations in which multiple ventilators may be considered medically necessary are:

1. An individual requires one type of ventilator (e.g., a negative pressure ventilator with a chest shell) for part of the day and needs a different type of ventilator (e.g., positive pressure ventilator with a nasal mask) during the rest of the day.
2. An individual who is confined to a wheelchair requires a ventilator mounted on the wheelchair for use during the day and needs another ventilator of the same type for use while in bed.  Without both pieces of equipment, the individual may be prone to certain medical complications, may not be able to achieve certain appropriate medical outcomes, or may not be able to use the medical equipment effectively.

The term non-invasive ventilation refers to the delivery of ventilatory support without endotracheal intubation or tracheostomy.  Traditionally, non-invasive ventilation has been given with the use of devices that apply intermittent negative extra-thoracic pressure (non-invasive negative pressure ventilation).  More recently the use of non-invasive ventilation has greatly expanded with the advent of positive pressure ventilation that is delivered through a nasal or face mask (non-invasive positive pressure ventilation).

Tank-type negative-pressure ventilators, such as the Emerson iron lung or Drinker respirator, were the mainstay of ventilatory support during the polio epidemics in the 1950's.  Although the tank ventilator is reliable, it is bulky (3 meters long) and heavy (300 kg), virtually precluding portability.  A more portable fiberglass tank ventilator is available (Portalung, Nellcor Puritan Bennett, St. Louis, MO), but it weighs approximately 50 kg and requires 2 persons to move.  Subsequently, less bulky, more portable negative-pressure ventilators were developed.  Today, the most commonly used negative-pressure ventilator is the poncho wrap (or jacket) ventilator (Numowrap, Respironics, Inc., Pittsburgh, PA), which consists of an impermeable nylon jacket suspended by a rigid chest piece that fits over the chest and abdomen.  The cuirass (or tortoise shell) ventilator is another negative-pressure device, which consists of a rigid plastic or metal dome over the chest and abdomen.  The chest and wrap ventilators are lightweight, but both must be connected to negative-pressure generators, which weigh 15 to 30 kg, such as the Maxi-vent (Nellcor Puritan Bennett, St. Louis, MO), Emerson NPV (J.J. Emerson, Inc., Cambridge, MA), or NEV-100 (Respironics, Inc., Pittsburgh, PA).

Negative-pressure ventilators work by intermittently applying a sub-atmospheric pressure to the chest wall and abdomen; this increases transpulmonary pressure and causes atmospheric pressure at the mouth to inflate the lungs.  Expiration occurs passively by elastic recoil of the lung and chest wall as pressure within the device rises to atmospheric levels.  Several uncontrolled studies reported benefits of intermittent negative pressure ventilation in patients with chronic respiratory failure due to chest wall deformity, neuromuscular diseases, and central hypoventilation.  In patients with stable, severe chronic obstructive pulmonary disease (COPD), however, a large randomized controlled trial found that negative pressure ventilation had no benefit (Shapiro, 1992).  The non-invasive use of positive-pressure ventilators has now superseded negative-pressure treatment for COPD.

Regarding use of noninvasive negative pressure ventilation in COPD, the Global Initiative for Chronic Obstructive Lung Disease (GOLD, 2010) concluded that negative pressure ventilation is not indicated for the chronic management of stage IV, very severe COPD patients, with or without CO2 retention. The GOLD guidelines state that negative pressure ventilation has been demonstrated to have no effect on shortness of breath, exercise tolerance, arterial blood gases, respiratory muscle strength, or quality of life in COPD patients with chronic respiratory failure.

In recent years, negative-pressure ventilation has been used infrequently for the management of patients with acute respiratory failure.  In a review of the literature on non-invasive ventilation, Hillberg and Johnson (1997) noted that the role of negative pressure ventilation in the management of acute respiratory failure is unclear.  Studies of the use of the body ventilator or poncho wrap for patients with acute respiratory failure and COPD, neuromuscular disease, or chest wall deformity suggest some benefit from these devices, but the studies have not been prospective and controlled.

Hillberg and Johnson (1997) also noted that negative pressure ventilation has not been widely used, because of poor acceptance by patients, inadequate effectiveness for many patients, the awkward size of the devices, and the development of upper airway obstruction in some patients.  Candidates for non-invasive negative-pressure ventilation with chronic respiratory failure should have at least mild to moderate daytime CO₂ retention (usually an indication of more severe nocturnal CO₂ retention).  Candidates with mild CO₂ retention should also have symptoms attributable to hypoventilation and associated poor sleep quality such as morning headache, daytime hypersomnolence, and energy loss.  In the absence of evidence of daytime CO₂ retention, there should be direct evidence of nocturnal hypoventilation and oxygen desaturation.  A recent consensus conference concluded that a PaCO₂ greater than 45 mm Hg or abnormal nocturnal oxygen saturation was a sufficient indication for non-invasive ventilation (Robert, 1993; NAMDRC, 1999).  Clinically significant hypoxemia during sleep has been defined as oxyhemoglobin saturation of less than 88 % for at least 5 minutes (NAMDRC, 1999).

Patients with stable or slowly progressive neuromuscular diseases, central hypoventilation, or chest wall deformities are the best candidates for non-invasive negative-pressure ventilation.  On the other hand, patients with rapidly progressive neuromuscular processes like Guillian-Barre syndrome are poor candidates.

Appropriate candidates for non-invasive ventilation should have adequate upper airway function and no excessive airway secretions.  Non-invasive ventilation is not indicated in diseases that affect the upper airways, such as amyotrophic lateral sclerosis.  Reversible underlying disorders that may be contributing to the patient's symptoms (e.g., hypothyroidism, congestive heart failure, etc.) should be adequately treated.  In general, non-invasive ventilation should not be used in patients who are unable to cooperate or who have impaired consciousness, problems with retained secretions, or hemodynamic instability.

Shah and colleagues (2013) stated that acute hypoxemic respiratory failure (AHRF) is an important cause of mortality and morbidity in children.  Positive pressure ventilation is currently the standard care; however, it does have complications.  Continuous negative extrathoracic pressure (CNEP) ventilation or continuous positive airway pressure (CPAP) ventilation delivered via non-invasive approaches (Ni-CPAP) have shown certain beneficial effects in animal and uncontrolled human studies.  In a Cochrane review, these researchers evaluated the effectiveness of CNEP or Ni-CPAP compared to conventional ventilation in children (at least 1 month old and less than 18 years of age) with AHRF due to non-cardiogenic causes for improving the mortality or morbidity associated with AHRF.  These investigators searched CENTRAL 2013, Issue 6, MEDLINE (January 1966 to week 3 of June 2013), EMBASE (1980 to July 2013) and CINAHL (1982 to July 2013).  Randomized or quasi-randomized clinical trials of CNEP or Ni-CPAP versus standard therapy (including positive pressure ventilation) involving children (from 1 month old to less than 18 years at time of randomization) who met the criteria for diagnosis of AHRF with at least one of the outcomes reported.  These researchers assessed risk of bias of the included studies using allocation concealment, blinding of intervention, completeness of follow-up and blinding of outcome measurements.  They abstracted data on relevant outcomes and estimated the effect size by calculating risk ratio (RR) and risk difference (RD) with 95 % confidence intervals (CI).  These investigators identified 2 eligible studies: 1 of CPAP and 1 of CNEP (published as an abstract).  Both were un-blinded studies with mainly unclear risk of bias due to lack of adequate information to assess this.  The CPAP study enrolled 37 children to oxygen mask and CPAP and reported improvement in respiratory rate and oxygen saturation in both arms after 30 mins of application.  The CNEP study was published as an abstract and included 33 infants with bronchiolitis.  In the CNEP study there was a reduction in the fraction of inspired oxygen (FiO2) (less than 30 % within 1 hour of initiation of therapy) in 4 participants in the CNEP group compared to none in the control group (RR 10.7, 95 % CI: 0.6 to 183.9).  One infant required CPAP and mechanical ventilation in the control group while all infants in the CNEP group were managed without intubation (RR for both outcomes 0.40, 95 % CI: 0.02 to 9.06).  None of the trials reported on mortality.  No adverse events were reported in ether of the included trials.  The authors concluded that there is a lack of well-designed, controlled trials of non-invasive modes of respiratory support in children with AHRF.  Moreover, they stated that studies assessing the outcomes mortality, avoidance of intubation and its associated complications, hospital stay and patient comfort are needed.

Appendix

Selection Criteria for Non-invasive Negative Pressure Ventilation:

Aetna considers non-invasive negative pressure ventilation medically necessary DME for members who meet the following criteria:

1. Member has been diagnosed with any of the following conditions: 

   1. Central hypoventilation (i.e., apnea not due to airway obstruction); or
   2. Chest wall deformity (e.g., post-thoracoplasty for tuberculosis, etc.), or 
   3. Slowly progressive neuromuscular diseases (e.g., muscular dystrophies, poliomyelitis, multiple sclerosis, spinal cord diseases, diaphragmatic paralysis, etc.), and
2. Member has chronic stable or slowly progressive respiratory failure that meets any of the following criteria:  

   1. Significant CO₂ retention (PaCO₂ greater than 50 mm Hg); or  
   2. Mild CO₂ retention (PaCO₂ greater than 45 mm Hg) with any of the following symptoms:  

      1. Cognitive dysfunction; or
      2. Daytime hypersomnolence, or
      3. Morning headache, or  

   3. Documented nocturnal hypoventilation or oxygen desaturation (with oxyhemoglobin saturation less than 88 % for at least 5 minutes).