Negative Pressure Ventilator - Modern Usage

Modern Usage

Rows of iron lungs filled hospital wards at the height of the polio outbreaks of the 1940s and 1950s. Polio vaccination programs have virtually eradicated new cases of poliomyelitis in the United States. Because of this, and also the development of modern ventilators and widespread use of tracheal intubation and tracheotomy, the iron lung has virtually disappeared from modern medicine. For example, in 1959, there were 1,200 people using tank respirators in the United States, but by 2004 there were only 39.

Positive pressure ventilation systems are now more common than negative pressure systems. Positive pressure ventilators work by blowing air into the patient's lungs via intubation through the airway; they were used for the first time in Blegdams Hospital, Copenhagen, Denmark during a polio outbreak in 1952. It proved a success and soon superseded the iron lung throughout Europe.

The iron lung now has a marginal place in modern respiratory therapy. Most patients with paralysis of the breathing muscles use modern mechanical ventilators that push air into the airway with positive pressure. These are generally efficacious and have the advantage of not restricting patients' movements or caregivers' ability to examine the patients as significantly as an iron lung does. However, negative pressure ventilation is a truer approximation of normal physiological breathing and results in more normal distribution of air in the lungs. It may also be preferable in certain rare conditions, such as Ondine's curse, in which failure of the medullary respiratory centers at the base of the brain result in patients having no autonomic control of breathing. At least one reported polio patient, Dianne Odell, had a spinal deformity that caused the use of mechanical ventilators to be contraindicated. There are patients who today still use the older machines, often in their homes, despite the occasional difficulty of finding the various replacement parts. Joan Headley of Post-Polio Health International stated to CNN that as of May 28, 2008, there were approximately 30 patients in the USA still using an iron lung. That figure may be inaccurately low; Houston alone had 19 iron lung patients living at home in 2008. Martha Mason of Lattimore, North Carolina died on May 4, 2009, after spending 60 of her 72 years in an iron lung.

On the 30th of October 2009, June Middleton of Melbourne, Australia, who had been entered in the Guinness Book of Records as the person who spent the longest time in an iron lung, died aged 83, having spent more than 60 years in her iron lung.

Biphasic Cuirass Ventilation is a modern development of the iron lung, consisting of a wearable rigid upper-body shell (a cuirass) which functions as a negative pressure ventilator.