Influence of Body Positioning on Pulmonary Aeration Among Mechanically Ventilated Critical Ill Patients
Phase: NA
Conditions: Critical Illness
Sponsor: Hospital Moinhos de Vento

 
 
 
Body Positioning and Pulmonary Aeration 
During Mechanical Ventilation 
 
 
 

NCT number: 04176445 
 
Date of the document: 04/27/2020  
 

Scientific background 
Invasive mechanical ventilation (IMV), despite saving lives in intensive care unit (ICU), 
may result in neuromuscular damage and impairment of the respiratory system. This damage 
can be worsened by immobilization in bed or reduced by using protocols of body positioning.  
Body positioning is associated with positive effects on respiratory system among 
patients requiring invasive mechanical ventilation, mainly when performed outside the bed. For 
example, the combination of sedestation in a chair and physical activity can improve lung 
aeration during IMV using endotracheal tube. Accordingly, passive orthostasis with the support 
of a tilt table has been incorporated into practice in order to allow body positioning of critical 
care patients outside the bed. When included in daily practice, this strategy, is associated with 
improvement of the level of consciousness of ICU patients. Moreover, when patients under 
IMV are placed in passive orthostasis using a tilt table, there is a transient increase in minute 
volume without a significant change in oxygenation. Nevertheless, the evidence regarding its 
safety and effectiveness in comparison with other body positioning strategies is still scarce, and 
the fulfillment of this evidence gap may contribute to improve mobilization outcomes of 
critically ill patients. Therefore, this study aimed to assess the effects of different mobilization 
positions on lung aeration of critically ill patients under IMV. 
 
Methods 
Study design 
The present study was designed to be an open label, randomized, crossover, two-center, 
clinical trial aimed to assess the impact of different verticalization positions on lung aeration of 
patients hospitalized in the ICU under invasive mechanical ventilation using endotracheal tube. 
Patients were enrolled and followed from the medical-surgical ICUs of Ernesto Dornelles (40 
beds) and Moinhos de Vento hospitals (17 beds), both tertiary, academic, and private hospitals, 
in Southern Brazil. 

 Sitting position protocol: Participants were passively placed in bedside sedestation, 
where they remained for 30 minutes, with back support; their hips and knees were flexed at 90º 
and feet supported. This position aimed at simulating sitting in a chair. 
Passive orthostasis protocol: Participants were transferred to a tilt table (0º 
inclination). Safety straps were placed on the knees, waist and chest to keep participants in the 
orthostatic position. The tilt table protocol lasted 30 minutes. Initially, participants were placed 
in a vertical position up to 45º and remained in this position for 3 minutes. Next, they were tilted 
to 60º, where they remained for 2 minutes. Then verticalization was performed up to 75-85º, 
where they remained for another 25 minutes. 
 Co-interventions: Endotracheal aspiration was performed 30 minutes before the 
beginning of both verticalization position protocols. The critical care management of 
participants, including IMV parameters were left at the discretion of each center assistant team 
according to local protocols.  
Randomization, washout, and bliding  
Subjects were randomized in an 1:1 ratio to one of two sequences of verticalization 
protocols: sitting position followed by passive orthostasis or passive orthostasis followed by 
sitting position. Participants were randomized on the same day they were deemed to be suited to 
participate in the study. Randomization was performed using blocks of different sizes and 
stratified by center. Allocation concealment was ensured through the use of a centralized 
webbased randomization plataform (REDCap, Vanderbilt University, Nashville, TN, USA). 
Researchers had access to intervention sequence only after the participants were registered on 
the platform. A washout window period (90 to 150 minutes) in which the patient was returned 
to bed in supine position (end of the first verticalization protocol) was applied between the two 
verticalization protocols to avoid the carryover effect. Considering the nature of the trial 
interventions, blinding was not feasible. 
Statistical Analysis Plan  

Baseline categorical variables were described as absolute and relative frequencies, while 
baseline quantitative variables were expressed as mean and standard deviation (SD).  Subjects 
were analyzed according to their randomization group, regardeless of treatment they received. 
Paired Student’s T test was used to compare the primary outcome between the two 
interventions. For secondary outcomes, categorical outcomes were assessed using the 
McNemar’s test, symmetrical continuous outcomes were assessed using the Paired Student ‘s T 
test, and asymmetrical continuous outcomes were assessed using the Wilcoxon’s signed-rank 
test. A significance level of 5% was set for all analyses.