218 Improvised Automatic Lung Ventilation for Use in Disasters

Abstract

Background: Large-scale disasters, such as accidental chemical spills or strategic use of nerve gas, may result in great numbers of casualties requiring mechanical ventilation. The number of ventilators required may exceed the supply. Objective: To develop improvised breathing circuits that extend the capability of a single ventilator to provide ventilation support to several patients during critical emergencies. Methods: Two types of circuits were assembled from readily available, inexpensive components. One delivers the tidal volume (V t ) directly to the patient and the other does so through a number of secondary circuits in parallel. Both types require an additional source of fresh gas flow (FGF) for each patient. An examination was made of the role of ventilator V t , inspiratory time, frequency, and FGF on delivered V t using mechanical lung simulators. Results: Each circuit type can provide individual patient V t , inspired oxygen concentration, and positive end-expiratory pressure (PEEP). The secondary circuit configuration is more efficient in terms of FGF usage, but is more complex with respect to mode of operation. Conclusions: A description is provided of two breathing circuits assembled from easily accessible components. Each can provide automatic ventilation to several patients with a single ventilator during emergencies.

Multiplex Ventilation: Solutions for Four Main Safety Problems

“…Studies Using Lung Simulators One study 21 built a circuit based on the "bag-in-the-box" concept from Sommer et al 7 to provide individualization of volume delivery to 2 simulators. The design of this study lacked individual monitoring of volume and PEEP.…”

“…These ventilator shortages spawned several reports describing circuit modifications that allow mechanical ventilation of 2 or more patients with a single ventilator. 4,6 Sommer et al 7 described a system for ventilating 2 patients with a single device in 1994, which involved a "bag-in-the-box" system, as is commonly accomplished using anesthesia devices. In 2002, Lerner 8 received a patent for a system he termed "multiplex ventilation," describing a device with a single gas source, a controller, and a series of flow regulators to provide support for up to 8 patients.…”

Design of a flow modulation device to facilitate individualized ventilation in a shared ventilator setup

“…Several factors are crucial in this context, including the number of patients, the onset and development of Acute Respiratory Distress Syndrome (ARDS), and the duration of morbidity [ 1 ]. Although Neyman and Irvin are commonly cited first to have discussed shared ventilation [ 5 ], the original idea to increase the patient capacity of a ventilator was first described in 1994 by Sommer et al with an anaesthesia-style, bag-in-the-box system in a limited proof-of-concept [ 6 ]. In 2002, a patent was granted to Lerner for ‘multiplex ventilation’, a system that could ventilate up to eight patients with a single gas source, again without further scientific elaboration or described applications [ 7 ].…”