Negative pressure ventilation come full circle?

The respiratory therapy profession basically began with the iron lung, or negative pressure ventilator. Wouldn't it be ironic if this type of therapy made a comeback, and negative pressure ventilators were the wave of the RT future.

The latest negative pressure ventilator is called the Biphasic Cuirass Ventilation, and one such ventilator is the Medivent Hayek RTX Biphasic Cuirass Ventilator made by Medivent International, and involves a simple shell placed over the patient's chest, instead of over the entire body as was the case with the inconvenient iron lung of the 1950s.

I can certainly see some advantages of the cuirass ventilator. For one thing, you would avoid the barotrauma associated with positive pressure ventilators and the risk of pulmonary infection because you wouldn't have a tube in the patient's airway nor a tracheotomy.

According to this company, since negative pressure ventilation is "more normal," it would be more comfortable for the patient, and allow RTs greater control over tidal volume and respiratory rate, and, ultimately, make weaning easier.

Likewise, the company claims that the vent "helps to maintain and redevelop the respiratory muscles which often wither and waste with respiratory failure and mechanical ventilation (and also) improves cardiac output."

Here are some more uses, as listed on Medivent International's website:

• It can be used as an aid in weaning a patient from conventional positive pressure vents, particularly those difficult to wean patients.
• Assists patient with removal of secretions, and is used as a glorified chest physiotherapy machine. It has been used in this way for Cystic Fibrosis patients and COPD patients.
• Can be used similar to BiPAP to provide treatment for patients before their condition deteriorates, and thus requiring intubation.
• Can be used as an at home vent and in hospitals for neuromuscular diseases and head and spinal injuries.
• It has been used on post-operative patients
• Can be used on Asthma and COPD patients

This type of therapy would be better for the patient in that they wouldn't have to have a tube in their throat, which can be very uncomfortable and annoying, and requires, most of the time, that sedative be used to make the patient more comfortable, or to forget the event all together. Sometimes this can make weaning difficult.

However, despite these claims, I'm not convinced this machine would be anything more than a glorified and expensive BiPAP machine, of course without the annoying and often difficult to get used to nasal or face mask.

I can also think of some cases where this type of ventilator would not be beneficial, especially if you had excessive secretions or pulmonary edema. Of course, even in these cases, nasal tracheal suctioning would always be an option.

However, this type of breathing apparatus would not protect the patient's lungs from aspiration, may not allow for adequate removal of CO2, and may not be effective for obese patients. In these cases, RTs and doctors would have no choice but to opt for the more conventional positive pressure ventilator.

Wikepedia has a nice write up about the curiass ventilator, but it would appear someone from Medivent International transcribed the copy here from their own website, as it's basically the same information not even reworded.

Anyway, that's my review of this ventilator based on some quick research I did. I wonder if this has been used anywhere in the U.S. If so, I wonder what the general opinion of this innovative therapy is, as so far most of what I've learned regarding this vent has been from the company.