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Canadian Journal of Anesthesia 54:420-429 (2007)
© Canadian Anesthesiologists' Society, 2007
Reports of Original Investigations

Tracheal pressure regulated volume assist ventilation in acute respiratory failure

[Ventilation débit-assistée régulée par pression trachéale dans les cas d’insuffisance respiratoire aiguë]

Tomislav Mirkovic, MD*, Vesna Paver-Erzen, MD PhD*, Tomislav Klokocovnik, MD PhD{dagger}, Ashvini Gursahaney, MD{ddagger}, Paul Hernandez, MD{ddagger} and Stewart B. Gottfried, MD{ddagger}

* From the Clinical Departments for Anesthesiology and Surgical Intensive Care, and
{dagger} Cardiovascular Surgery, UMC Ljubljana, Slovenia; and the
{ddagger} Divisions of Respiratory and Critical Care Medicine, Department of Medicine, McGill University Health Centre and Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada.

Address correspondence to: Dr. Stewart B. Gottfried, McGill University Health Centre, Royal Victoria Hospital, 687 Pine Avenue West, Room M4.10, Montreal, Quebec H3A 1A1, Canada. Phone: 514-934-1934, ext. 36117; Fax: 514-843-1695; E-mail: stewart.gottfried{at}muhc.mcgill.ca

Purpose: Proportional assist ventilation (PAV) uses volume assist (VAV) and flow assist ventilation (FAV) to reduce elastic and resistive effort, respectively. Proportional assist ventilation may be difficult to apply clinically, particularly due to FAV related considerations. It was hypothesized that regulating tracheal (Ptr) rather than airway opening pressure (Pao), to overcome endotracheal tube related resistive effort, during VAV would provide an effective alternative method of ventilation. We therefore compared the effects of Pao and Ptr regulated VAV on breathing pattern and inspiratory effort.

Methods: In seven intubated patients, flow, volume, Pao, Ptr, esophageal and transdiaphragmatic pressure were measured during VAV (0–80% respiratory system elastance) using Pao vs Ptr to regulate ventilator applied pressure. Breathing pattern and the pressure-time integral of the inspiratory muscles ({int}Pmus · dt) and diaphragm ({int}Pdi · dt) were determined.

Results: Compared to spontaneous breathing, the respiratory rate to tidal volume ratio, or rapid shallow breathing index (RSBI), improved progressively with increasing VAV (130 ± 64 vs 70 ± 35, VAV 0 vs 80%; P < 0.05) while inspiratory effort fell ({int}Pmus · dt = 39.6 ± 7.5 vs 28.5 ± 7.2 cm H2O·sec·L–1, {int}Pdi · dt, = 35.4 ± 7.8 vs 24.2 ± 5.9 cm H2O·sec·L–1, VAV 0 vs 80%; P < 0.05) due to a decrease in elastic related effort. At any given level of support, there was further reduction in RSBI, {int}Pmus · dt, and {int}Pdi · dt (which averaged 23.6 ± 2.7, 33.7 ± 4.4, and 38.5 ± 5.1%, respectively; P < 0.05) for Ptr compared to Pao regulated VAV due to a decrease in resistive effort.

Conclusions: Tracheal pressure regulated VAV can be a simple and effective method of partial ventilatory support in acute respiratory failure. Further work will be needed to determine its efficacy and potential benefit relative to PAV and other modes of ventilation in routine clinical practice.


Related articles in CJA:

Enhancing ventilatory strategies for the critically ill – proportional assist ventilation/L’amélioration des stratégies respiratoires pour les patients sévèrement malades – la ventilation assistée proportionnelle
Martin R. Lessard
CJA 2007 54: 407-413. [Full Text]  



This article has been cited by other articles:


Home page
 Canadian J. AnesthesiaHome page
M. R. Lessard
Enhancing ventilatory strategies for the critically ill - proportional assist ventilation/L'amelioration des strategies respiratoires pour les patients severement malades - la ventilation assistee proportionnelle
Can J Anesth, June 1, 2007; 54(6): 407 - 413.
[Full Text] [PDF]


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