Impact of Non-invasive Positive Pressure Ventilation on Cardiac Function and Echocardiographic Parameters

Hemodynamics Clinical Trial

Official title:

Impact of Non-invasive Positive Pressure Ventilation on Cardiac Function and Echocardiographic Parameters

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02267291
• Other study ID #: 104/14
• Status: Completed
• Phase: N/A
• Start date: June 2015
• Est. completion date: February 2018

Study information

• Verified date: October 2018
• Source: University Hospital Inselspital, Berne
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Cardiologists and intensive care specialists are confronted daily with mechanically ventilated patients exhibiting cardiac failure. It is of paramount importance to understand the effect of mechanical ventilation on cardiac function and to interpret echocardiographic findings correctly in order to provide the patient with the best possible treatment to support cardiac and circulatory function. Currently physicians interpret echocardiographic findings based on studies that were performed in spontaneously breathing patients. With this study, the investigators intend to contribute to the understanding of cardiac physiology in patients needing ventilatory support, especially they aim to provide the physiological basis for the interpretation of echocardiographic findings in order to improve medical support (e.g. fluid resuscitation, vasoactive drugs, ventilation strategy) of ventilated patients with impaired cardiovascular function.

Description:

Background

Mechanical ventilation (MV) is commonly used in intensive care units (ICU) to improve gas exchange and to reduce breathing effort. The need for MV is the single most prominent reason for admission to an intensive care unit, either for acute cardiac or respiratory failure, postoperative ventilation or other reasons. Its usefulness is not limited to critically ill patients but has also gained recognition in treating sleep-related breathing disorders. Soon after the introduction of MV to clinical practice its adverse hemodynamic effects were noted and have been studied ever since. It is now well accepted that MV, by applying external positive pressure in order to achieve tidal breathing, affects lung volume and intrathoracic pressure which in turn influence cardiac loading and function.

Echocardiography is increasingly used in intensive care to evaluate hemodynamics and especially Doppler assessments of mitral inflow and annular tissue velocity to describe left ventricular (LV) diastolic function. There is a growing body of evidence stating that diastolic dysfunction is a key factor for weaning failure from MV, a clinical issue affecting up to one third of patients. Worsened diastolic LV filling under MV may decisively lower cardiac performance and cause hemodynamic instability especially in case of pre-existing diastolic dysfunction in patients with arterial hypertension, a disease with a high prevalence of 30-45% in the general population. So far, despite the extensive use of echocardiography in ventilated patients, the causative pathophysiological mechanisms underlying ventilation-induced changes of echocardiographic parameters used to determine diastolic LV function have never been thoroughly evaluated. Assessing diastolic function during MV is complex since Doppler derived surrogate parameters all depend on cardiac loading conditions and loading itself is inevitably coupled to MV. The question therefore arises whether echocardiography allows for detection of deteriorating LV diastolic function in terms of impaired intrinsic ventricular relaxation or LV stiffness or whether it primarily mirrors MV-induced loading alterations. It is important to differentiate if echocardiographic signs of diastolic dysfunction in the patient under MV are caused by changes in loading or a LV filling restraint since in case of hemodynamic instability the two scenarios would ask for different therapeutic measures. In case of a loading problem, pre- and afterload can be targeted using drugs or fluid resuscitation. If a MV-induced filling restraint is the predominant problem one may consider special ventilatory modes or even deep sedation and the use of muscle relaxants to minimize Pit.

The basic concepts of heart-lung interactions under positive pressure ventilation make it conceivable that extrinsic pressure applied to the thorax and therefore, as explained later in more detail, to the heart may mimic diastolic dysfunction even in a totally healthy heart if assessed by echocardiography. Echocardiographic parameters to assess diastolic function have been evaluated against the gold standard - invasive LV pressure and volume measurements

• in spontaneously breathing patients. Such an evaluation is lacking for the patient with ventilatory support and therefore the value of echocardiography for assessment of diastolic function under MV needs further clarification. The investigators intend to comparatively study cardiac and particularly left ventricular diastolic function in ventilated patients using both invasive and ultrasound methods.

Objective

The presented study will elucidate the influence of positive pressure ventilation on cardiac function in humans. Furthermore, the investigators aim to describe the changes of echocardiographic parameters under different levels of positive pressure ventilation and link these changes to the underlying pathophysiological alterations in hemodynamics induced by positive pressure ventilation.

Methods

Prospective single-centre study at the University Hospital Berne. 30 patients scheduled for an elective coronary angiogram will be included. During spontaneous breathing and two different levels of non-invasive PPV transthoracic echocardiography is performed while recording LV-pressure-volume loops using an impedance catheter. Simultaneously the pulmonary artery occlusion pressure, the right atrial pressure and the intrathoracic pressure are recorded using a pulmonary artery catheter and an oesophageal balloon respectively.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 30
• Est. completion date: February 2018
• Est. primary completion date: February 2018
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years to 75 Years

Eligibility

Inclusion Criteria:

• Age = 18 to = 75 years

• Indication for a coronary angiogram

• Written informed consent obtained

• Adequate echocardiographic imaging quality

• • Patient tolerates a face mask for non-invasive ventilation

Exclusion Criteria

• Acute coronary syndrome

• Previous myocardial infarction or open heart surgery

• Severe obstructive or restrictive pulmonary disease

• Pulmonary hypertension

• Diastolic dysfunction = grade II

• Valvular heart disease > grade I

• Left ventricular ejection fraction < 50%

• Complete left or right bundle branch block

• Cardiac pacemaker or defibrillator

• Atrial fibrillation or frequent premature beats

• INR > 3.0 or haemoglobin < 90g/l

• Glomerular filtration rate < 45ml/min/1.73m2

• Esophageal disorders

Related Conditions & MeSH terms

• Circulatory and Respiratory Physiological Phenomena
• Heart Function Tests
• Hemodynamics
• Noninvasive Ventilation

Intervention

Other:
• Non-invasive positive pressure ventilation
Ventilatory support to alter intrathoracic pressure

Locations

Country	Name	City	State
Switzerland	Department of Cardiology, Bern University Hospital	Bern	BE

Sponsors (1)

Lead Sponsor	Collaborator
University Hospital Inselspital, Berne

Country where clinical trial is conducted

Switzerland, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Left ventricular diastolic function	Assessed by pressure volume loops	Under spontaneous breathing and at two levels of positive pressure ventilation, 5 minutes after changing positive end-expiratory pressure
Secondary	Left ventricular contractility	Assessed by pressure volume loops	Under spontaneous breathing and at two levels of positive pressure ventilation, 5 minutes after changing positive end-expiratory pressure
Secondary	Cardiac function	Assessed by echocardiography	Under spontaneous breathing and at two levels of positive pressure ventilation, 5 minutes after changing positive end-expiratory pressure
Secondary	Invasively measured alterations in hemodynamics	Alterations of invasively measured hemodynamic parameters including cardiac output and pulmonary artery, right ventricular and right atrial pressures	Under spontaneous breathing and at two levels of positive pressure ventilation, 5 minutes after changing positive end-expiratory pressure