Elsevier

Resuscitation

Volume 49, Issue 2, May 2001, Pages 159-167
Resuscitation

Work of breathing characteristics of seven portable ventilators

https://doi.org/10.1016/S0300-9572(00)00358-0Get rights and content

Abstract

Portable ventilators (PVs) are used for patient transport with increasingly frequency. Due to design differences it would not be unexpected to find differences among these ventilators in the imposed work of breathing (WOBI) during spontaneous respiratory efforts. The purpose of this investigation was to compare the WOBI characteristics during spontaneous breathing of seven PVs; Bird Avian, Bio-Med Crossvent 4, Pulmonetics LTV 1000, Hamilton Max, Drägerwerk Oxylog 2000, Impact Uni-Vent 750, and Impact Uni-Vent 754 using a model of spontaneous breathing. Differences between the PVs in regards to the measured parameters increased with increases in simulated breathing demand. WOBI, peak inspiratory pressure, and pressure-time product were consistently less with the LTV 1000 over the range of simulated breathing conditions. During pressure support ventilation these parameters were significantly less with the LTV 1000 compared with the Crossvent 4. Only the WOBI produced by the LTV was consistently lower than the physiologic work of breathing across the simulated spontaneous breathing conditions. Based on these results it is predicted PVs with flow triggering and positive end-expiratory pressure compensation will consistently offer the least WOBI. Clinicians should be aware of these characteristics when using PVs with spontaneous breathing patients.

Resumen

Os Ventiladores Portáteis (VP) são cada vez mais usados para o transporte de doentes. Sendo aparelhos com desenhos diferentes, não seria inesperado encontrar diferenças entre esses ventiladores relativamente ao Trabalho Respiratório Imposto (TRI) durante os esforços de ventilação espontânea. O objectivo deste investigação foi comparar as caracterı́sticas do TRI durante a ventilação espontânea em sete Ventiladores Portáteis; Bird Avian, Bio-Med Crossvent 4, Pulmonetics TLV 1000; Hamilton Max, Dragerwerk Oxylog 2000, Impact Uni-Vent 750 e Impact Uni-Vent 754 usando um modelo de ventilação espontânea. As diferenças entre os VP relativamente aos parâmetros medidos são maiores à medida que as solicitações ventilatórias simuladas são maiores. O TRI, a Pressão Inspiratória de Pico e o Produto Pressão-Tempo de Pico foram consistentemente menores com o LTV 1000 na faixa de condições respiratórias simuladas. Em pressão assistida aqueles parametros foram significativamente menores com o LTV100 em confronto com o Crossvent 4. Só com o LTV é que o TRI foi consistentemente inferior ao trabalho respiratório fisiológico em condições simuladas de respiração espontânea. Com base nestes resultados é de prever que os VP com sensores de fluxo e capacidade para fazerem pressão positiva no final da expiração proporcionem consistentemente condições para que o TBI seja menor.

Introduction

The intra- and interhospital transport of critically ill patients requiring mechanical ventilation remains a challenge to practitioners. While manual ventilation of these patients with a self-inflating bag has been done of many years, work from our group and others has suggested a portable ventilator (PV) is safer and more likely to maintain ventilatory homeostasis [1], [2], [3]. Portable ventilators have become increasingly sophisticated, offering features once reserved for their intensive care unit (ICU) counterparts.

The imposed work of breathing (WOBI) is the work that must be done by the patient to overcome the resistance of any additional apparatus including the artificial airway, breathing circuit, and ventilator [4]. An excessive WOBI may cause patient discomfort and may lead to respiratory failure [4].

The purpose of this investigation was to compare the WOBI of seven PVs over a range of simulated breathing patterns.

Section snippets

General

Seven PVs were studied — one of each model. These ventilators were selected based on their size, portability, availability, and were acquired from the manufacturer or local hospitals. Table 1 offers a comparison of the various features of the devices.

Each of these ventilators is portable and operates from electrical sources including battery power. Except for the LTV 1000 and Uni-Vent 754, each requires a high pressure oxygen source for operation. The LTV 1000 uses a turbine and the Uni-Vent

Results

The data comparing the seven ventilators are offered in Table 2, Table 3, Table 4. Pressure-volume curves for the seven ventilators during simulated breathing (VT=0.5 l, PIF=60 l/min, PEEP=0 cm H2O, PSV=0 cm H2O) are depicted in Fig. 3. The data comparing the effects of PSV for the Crossvent 4 and LTV 1000, the only two ventilators of the group that offer PSV, are shown in Table 5.

During PSV (with and without PEEP), the delay time, PImax, WOBI, and PTP were lower with the LTV 1000 compared with

Discussion

During the less demanding simulated breathing conditions (VT=0.3 l, PIF=30 l/min and VT 0.5 l, PIF=60 l/min) there were few statistical or clinical differences between the ventilators. However during the most demanding simulated breathing condition (VT=0.8 l, PIF=80 l/min) the delay time, PImax, WOBI, and PTP of the LTV 1000 was statistically less than the other six ventilators. During PSV, the LTV 1000 consistently produced a lower delay time, PImax, WOBI, and PTP compared to the Crossvent 4.

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    The views expressed in this article are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense or the US Government.

    1

    The present address for the authors Robert S. Campbell, Jay A. Johannigman and Richard D. Branson is Department of Surgery ML 558, University of Cincinnati Medical Center, 231 Bethesda Ave, Cincinnati, OH 45267-0558, USA.

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