Expiratory Muscle Function in Critically Ill Ventilated Patients

Study Overview
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Brief Summary
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Inspiratory muscle weakness develops rapidly in ventilated critically ill patients and is associated with adverse outcome, including prolonged duration of mechanical ventilation and mortality. Surprisingly, the effects of critical illness on expiratory muscle function have not been studied. The main expiratory muscles are the abdominal wall muscles, including the external oblique (EO), internal oblique (IO) and transversus abdominis muscles (TRA). These muscles are activated when respiratory drive or load increases, which can be during e.g. exercise, diaphragm fatigue, increased airway resistance, or positive airway pressure ventilation. The abdominal wall muscles are also critical for protective reflexes, such as coughing. Reduced abdominal muscles strength may lead to decreased cough function and thus inadequate airway clearance. This will lead to secretion pooling in the lower airways, atelectasis, and ventilator associated pneumonia (VAP). Studies have shown that decreased cough function is a risk for weaning failure and (re)hospitalization for respiratory complications. Further, high mortality was found in patients with low peak expiratory flow. Considering the importance of a proper expiratory muscle function in critically ill patients, it is surprising that the prevalence, causes, and functional impact of changes in expiratory abdominal muscles thickness during mechanical ventilation (MV) for critically ill patients are still unknown. Ultrasound is increasingly used in the ICU for the visualization of respiratory muscles. In a recent pilot study the investigators confirmed the feasibility and reliability of using of ultrasound to evaluate both diaphragm and expiratory abdominal muscle thickness in ventilated critically ill patients (manuscript in preparation). Accordingly, the primary aim of the present study is to evaluate the evolution of abdominal expiratory muscle thickness during MV in adult critically ill patients, using ultrasound data.

Official Title
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Expiratory Muscle Function in Critically Ill Ventilated Patients

Conditions
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Critical Illness, Mechanical Ventilation, Expiratory Muscle, Muscle Atrophy or Weakness, Diaphragm

Intervention / Treatment
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* Other: Data from ultrasound measurements


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 18 years Invasive mechanical ventilation < 48 hours Expected duration of mechanical ventilation > 72 hours Exclusion Criteria: Past medical history of neuromuscular disorders Mechanical ventilation > 48 hours within the current hospital admission Pregnant women Open abdominal wounds at proposed location of the ultrasound probe, due to recent abdominal surgery

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: Data from ultrasound measurements|Data from ultrasound measurements and from the electronic patient record will be obtained / analyzed. One additional blood sample will be obtained within 24 hours after inclusion, during planned blood collection (from arterial line or venous puncture).|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Abdominal expiratory muscle thickness | Thickness of the abdominal expiratory muscles measured in millimeters | From the date of inclusion until the date of first extubation or date of death from any cause, whichever came first, assessed up to 6 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diaphragm muscle thickness | Thickness of the diaphragm muscle measured in millimeters | From the date of inclusion until the date of first extubation or date of death from any cause, whichever came first, assessed up to 6 weeks | 
| Inflammatory markers | Inflammatory markers (TNF-alpha, IL-6, IL-10) at inclusion (measured from blood sample using ELISA technique). | Within 24 hours after inclusion | 
| Applied driving pressure | Appplied driving pressuye defined as peak pressure minus total postive end expiratory pressure, and measured in centimetre of water | From the date of inclusion until the date of first extubation or date of death from any cause, whichever came first, assessed up to 6 weeks | 
| Tidal volume | Tidal volume measured in liters | From the date of inclusion until the date of first extubation or date of death from any cause, whichever came first, assessed up to 6 weeks | 
| Positive end expiratory pressure | Postive end expiratory pressure measure in centimetre of water | From the date of inclusion until the date of first extubation or date of death from any cause, whichever came first, assessed up to 6 weeks | 
| Extubation failure | Reintubated after extubation | From the date of extubation to the date of reintubation, or the date of death from any cause, or the date of ICU discharge, whichever came first, assessed up to 6 weeks | 
| Readmission to ICU | Readmitted to ICU after the ICU discharge | From the date of ICU diascharge to the date of death from any cause, or the date of hospital discharge, whichever came first, assessed up to 6 weeks |