TY - JOUR T1 - Is there still a negative side to noninvasive ventilation? JF - European Respiratory Journal JO - Eur Respir J SP - 361 LP - 362 DO - 10.1183/09031936.04.00133304 VL - 23 IS - 3 AU - N.S. Hill Y1 - 2004/03/01 UR - http://erj.ersjournals.com/content/23/3/361.abstract N2 - Negative pressure ventilation, the intermittent application of subatmospheric pressure around the chest and abdomen to assist breathing, is founded on sound physiological principles. As long as atmospheric pressure is maintained at the mouth and nose (and the upper airway remains patent), the negative peri-thoracic and -abdominal pressure increases the transpulmonary gradient, expanding the chest wall and lungs to assist inhalation. Exhalation is achieved mainly via passive recoil of the chest wall and lungs, although it is possible to assist this by imposing a supra-atmospheric peri-thoracic and -abdominal pressure, as was the case with the “iron lung” used by Corrado et al. 1, as described in the current issue of the European Respiratory Journal. In fact, negative pressure ventilation has a long and important history in the annals of mechanical ventilation, dating back to the 1800s, when the first tank-type negative pressure ventilator was described as a manually powered resuscitation device 2. The need for respiratory assist devices greatly increased during the polio epidemics of the first half of the 20th century, and the use of electrically powered “iron lungs”, such as that described by Drinker and Shaw 3, began to increase, becoming the main means of ventilatory support outside of the anaesthesia suite. These devices enclosed patients up to their necks in bulky, heavy metal chambers that limited access to patients for nursing care. Consequently, a number of smaller, more portable negative pressure devices were created, including the “cuirass” ventilator, which consisted of a rigid shell that was applied over the anterior chest and abdomen 4, and the “jacket” ventilator that consisted of a rigid cage suspended over the chest and abdomen that was placed within an impervious jacket 5. Both of these devices saw … ER -