Am. J. Respir. Crit. Care Med.,
Volume 163, Number 7, June 2001, 1614-1618
Physiologic Effects of Negative Pressure Ventilation in
Acute Exacerbation of Chronic Obstructive
Pulmonary Disease
MASSIMO
GORINI,
ANTONIO
CORRADO,
GIUSEPPE
VILLELLA,
ROBERTA
GINANNI,
ANNIKE
AUGUSTYNEN,
and
DONATELLA
TOZZI
Respiratory Intensive Care Unit, Careggi Hospital, Florence, Italy
To assess the physiologic effects of continuous negative extrathoracic pressure (CNEP), negative pressure ventilation (NPV), and negative extrathoracic end-expiratory pressure (NEEP) added to NPV
in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD), we measured in seven patients ventilatory pattern, arterial blood gases, respiratory mechanics, and pressure- time product of the diaphragm (PTPdi) under four conditions: (1) spontaneous breathing (SB); (2) CNEP (
5 cm H2O); (3) NPV; (4) NPV plus NEEP. CNEP and NPV were provided by a microprocessor-based iron lung capable of thermistor-triggering. Compared
with SB, CNEP improved slightly but significantly PaCO2 and pH,
and decreased PTPdi (388 ± 59 versus 302 ± 43 cm H2O · s, respectively, p < 0.05) and dynamic intrinsic positive end-expiratory
pressure (PEEPi) (4.6 ± 0.5 versus 2.1 ± 0.3 cm H2O, respectively,
p < 0.001). NPV increased minute ventilation (
E), improved arterial
blood gases, and decreased PTPdi to 34% of value during SB (p < 0.001). NEEP added to NPV further slightly decreased PTPdi and
improved patient-ventilator interaction by reducing dynamic PEEPi
and nontriggering inspiratory efforts. We conclude that CNEP and
NPV, provided by microprocessor-based iron lung, are able to improve ventilatory pattern and arterial blood gases, and to unload
inspiratory muscles in patients with acute exacerbation of COPD.