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NCT Number: NCT03244891

Autonomic Challenges From Mild Hypovolemia and Mechanical Ventilation

Heart Rate Variability (HRV) analysis has been studied in the critically ill patients although it is affected by several uncontrolled variables in the clinical conditions. The aim of this trial is to measure the effects of mildly reduced central volume and cyclic variation of intrathoracic pressure on the variables frequently used to describe the HRV.

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Key information

Conditions

Autonomic Nervous System Imbalance Hypovolemia Pathologic Processes Pathological Conditions, Signs and Symptoms Positive-Pressure Respiration

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

ASST Fatebenefratelli Sacco, Luigi Sacco Hospital

Milan, 20157, Italy

About this study

Twelve healthy volunteers will be studied. Mild hypovolemia will be induced by 12 hours fasting from food and drinks. At 8.30 AM the study protocol will start. The studied subjects will lie calm supine in a ICU bed able to provide passive head up and head down tilt. They will be connected to a Siemens SC9000 monitor showing their ECG waves and to a Nexfin (BMEYE) monitor for continuous noninvasive blood pressure (NBP) assessment. Both waves (ECG and NBP) will be recorded on a laptop PC through analogic/digital input/output converter (PowerLab 8/35, ADinstruments). The studied subjects will undergo to a sequence of (1) spontaneous breathing at 10 degrees head up, (2) spontaneous breathing at 7 degrees head down, (3) noninvasive ventilation at 10 degrees head up, and (4) noninvasive ventilation at 7 degrees head down. The sequence 1-2-3-4 will be randomized. After this four phases, a fluid challenge of ringer acetate 15ml*kg will be intravenously administered and the a sequence 1-2-3-4 will be repeated after a new randomization. Noninvasive ventilation will be provided with a facial mask with ventilatory setting: Psupp 8 cmH2O, PEEP 5 cmH2O, FiO2 0.28. Psupp will be decreased by 2 cmH2O steps if the inspiratory tidal volume will be >10ml*kg. During both spontaneous breathing and noninvasive ventilation the subjects will breathe following a metronome at 18bpm.

HRV analysis will be conducted following the recommendation of the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (see reference).

Furthermore, the healthy volunteers will be studied by trans-thoracic ultrasound assessment with a Philips EPIQ7 sonographer, during each study phase.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • healthy volunteers

Exclusion criteria

  • history of cardiac, metabolic, respiratory, renal, neurological or hematologic disease of any kind
  • chronically assuming drugs of any kind
  • non sinus cardiac rhythm
  • ectopic beats >5% of all cardiac beats
  • claustrophobia or unable to tolerate noninvasive ventilation via facial mask

Treatment and study plan

Increase of central volume

Other

Mild hypovolemia will be induced in healthy volunteers by 12 hours fasting. Three conditions will be considered for the analysis, each of them both during spontaneous breathing and positive pressure ventilation:

  • baseline
  • after fluid shift induced by passive head down position at 15 degrees
  • after fluid challenge with Ringer acetate 15ml*kg in head down position

A total of six steps will be considered for the analysis

Ventilation mode

Other

Each previous step will be done in two respiratory conditions:

  • spontaneous breathing
  • noninvasive ventilation via facial mask in pressure support mode at 8 cmH2O above positive end expiratory pressure of 5 cmH2O, inspiratory fraction of oxygen of 0.25 In both conditions respiratory rate will be set at 18 breaths per min following a metronome

Primary outcomes

  1. Effects of increasing central blood volume on heart rate variability

    Time frame: 10 mins each step

    The studied subjects will undergo to increase of central blood volume in two steps:

    • passive head down tilt at -7 degrees
    • intravenous infusion of ringer acetate of 15ml*kg body weight

  2. Effect of cyclic intrathoracic pressure oscillations on heart rate variability

    Time frame: 10 min each step

    The studied subject will undergo to two ventilatory modes:

    • spontaneous breathing at 18 breaths per min
    • positive pressure ventilation via face mask

Secondary outcomes

  1. Effects of increasing central blood volume and of cyclic intrathoracic pressure oscillations on echographic cardiac function variables

    Time frame: 10 mins each step

    At each step cardiac functionality assessment will be done by transthoracic echocardiography

Sponsors and collaborators

Lead sponsor

ASST Fatebenefratelli Sacco

Other

Registry information

Official study title

Effects of Low Central Volume and Intermittent Positive Pressure Ventilation on the Heart Rate Variability

Important dates

Study start
2019
Primary completion
2019
Study completion
2019
First posted
Aug 10, 2017
Registry last updated
Oct 14, 2019

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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