Weaning Patients Clinical Trial
Official title:
Liberal Versus Restrictive Transfusion Management in Patients Being Weaned From Prolonged Mechanical Ventilation
The aim of this study is to determine, whether a liberal transfusion strategy is helpful to
liberate patients from prolonged invasive mechanical ventilation.
Patients who are difficult to wean according to the criteria by Boles et al [1] are limited
by the capacity of their respiratory muscles.
Improved oxygen delivery achieved by blood transfusions however is known to decrease the
work of breathing [2] and thus in theory can improve weaning success [3].
This study is designed as a prospective, randomized, open labeled blinded End-point
evaluation to test the hypothesis that a liberal transfusion strategy decreases the time
needed for weaning.
1. Boles, JM, J Bion, A Connors, M Herridge, B Marsh, C Melot, R Pearl, H Silverman, M
Stanchina, A Vieillard-BaronandT Welte, Weaning from mechanical ventilation. Eur Respir
J, 2007. 29(5): p. 1033.
2. Schonhofer, B, M Wenzel, M GeibelandD Kohler, Blood transfusion and lung function in
chronically anemic patients with severe chronic obstructive pulmonary disease. Crit
Care Med, 1998. 26(11): p. 1824.
3. Schonhofer, B, H BohrerandD Kohler, Blood transfusion facilitating difficult weaning
from the ventilator. Anaesthesia, 1998. 53(2): p. 181.
Liberation from invasive mechanical ventilation has a huge impact on quality of life and
healthcare expenses. Weaning is more difficult and complex in patients who have been
ventilated for a longer time (i.e. more than seven days) or have undergone multiple failed
weaning attempts and thus are classified weaning category three according to Boles at al.
[1] Current national and international guidelines are in favour of a rather restrictive
transfusion regime. This recommendation is mainly based on the work of Hebert et al. [2]
where no benefit or a liberal transfusion approach could be found. Patients in the Hebert
study however had become acutely ill and did not show any impairment or dysfunction of the
respiratory muscles
Weaning class 3 patients however suffer from an overload of their respiratory muscles either
cause by an increased load or decreased capacity.
In either instance unloading of the respiratory muscles is key to improve the capability of
spontaneous breathing. One possible way to achieve this goal is to improve oxygen delivery.
Oxygen delivery is determined by the cardiac output times the oxygen content of the blood.
The latter is mainly determined by the haemoglobin concentration and the oxygen saturation
(Hb x 1.34 x SaO2 + PO2 x 0.003). Previous studies have shown that in patients with a
strained respiratory pump blood transfusions improve the work of breathing [3].
A more liberal transfusion strategy therefore might improve the weaning outcome ventilator
dependant patients [4]
This study is designed as a prospective, randomized, open labeled blinded End-point
evaluation to test the hypothesis that a liberal transfusion strategy decreases the time
needed for weaning.
Patients who are anemic (Hb < 9 mg/dl) and were admitted to our specialized weaning unit are
either randomized to a conservative or liberal transfusion regime if they are agreed to
participate.
The goal in the liberal transfusion group is to keep the Hb at > 12 mg/dl and transfusions
are given in single units until this threshold is achieved.
Patients then undergo routine weaning procedures consistent of daily or multiple daily
weaning trials paired with intermittent ventilation targeted do rest the respiratory
muscles.
Daily physiologic data are recorded as well as adverse events. Primary outcome is the time
needed to wean the patients off invasive mechanical ventilation, mortality is a secondary
criterium.
The study is planned to include 120 patients in blocks of 40 patients. Interim analysis will
be performed after each block and the study will be terminated if a significant result is
achieved.
1. Boles, JM, J Bion, A Connors, M Herridge, B Marsh, C Melot, R Pearl, H Silverman, M
Stanchina, A Vieillard-BaronandT Welte, Weaning from mechanical ventilation. Eur Respir
J, 2007. 29(5): p. 1033.
2. Hebert, PC, G Wells, MA Blajchman, J Marshall, C Martin, G Pagliarello, M Tweeddale, I
SchweitzerandE Yetisir, A multicenter, randomized, controlled clinical trial of
transfusion requirements in critical care. Transfusion Requirements in Critical Care
Investigators, Canadian Critical Care Trials Group. N Engl J Med, 1999. 340(6): p. 409.
3. Schonhofer, B, M Wenzel, M GeibelandD Kohler, Blood transfusion and lung function in
chronically anemic patients with severe chronic obstructive pulmonary disease. Crit
Care Med, 1998. 26(11): p. 1824.
4. Sato, T, EJ BedrickandC Tsai, Model Selection for Multivariate Regression in Small
Samples. Biometrics, 1998. 54(1): p. 391.
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Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment