Detecting a Volume Deficit During Spontaneous Breathing

Study Overview
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Brief Summary
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13 healthy volunteers (4 females) were tilted 45° head-up while breathing through a facemask fitted with an inspiratory and expiratory resistor. A brachial arterial catheter was used to measure blood pressure and thus systolic pressure variation and pulse contour analysis determined stroke volume and thereby cardiac output in order to detect a central volume deficit.

Detailed Description
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Thirteen healthy volunteers (4 women) at an age of 25 years (range 18-36) were recruited through www.forsøgsperson.dk. The volunteers were placed on a tilt table and provided with a facemask with an opening of 30-33 mm. A Hook ring was fitted with an inspiratory resistor, an expiratory resistor, a combination of the two resistors, or with no resistance and each resistor provides a 7.5 cmH2O threshold resistance. Each resistor was applied for two minutes with variables obtained in the last minute. The table was then tilted 45° head-up to accumulating blood in the legs and therefore a reduction in the central blood volume. Conversely, 20° head-down tilt was used to expand the central blood volume. For each volunteer measurements with the four respiratory interventions was randomized, whereas the tilt table position was in fixed order: supine, head-up tilt, and head-down tilt. Three-lead ECG recorded heart rate. A 20 G arterial catheter was placed in the brachial artery of the non-dominant arm and connected to a transducer for reading of blood pressure and stroke volume variation (Vigileo-Flotrac™, version 1.07, Edwards Lifesciences, Nyon, Switzerland). Also SV and CO variation and the arterial pressure curve were recorded for subsequent determination of arterial pressure variations. Additionally, a catheter was placed via a brachial vein to the superior caval vein for recording of central venous pressure and SvO2. While the subjects were breathing spontaneously, the respiratory rate was measured by capnography and peripheral oxygen saturation by fingerprobe. Variation in the arterial pulse pressure (PPV) was 100 x ((PPmax - PPmin) / ((PPmax + PPmin)/2)), where PPmax and PPmin is the maximal and minimal difference between systolic and diastolic pressure during the respiratory cycle, respectively. By the same formula systolic pressure variation (SPV) was calculated.

Official Title
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Detecting a Central Volume Deficit in Spontaneous Breathing Healthy Volunteers by Systolic Blood Pressure Variation

Conditions
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Hypovolemia

Intervention / Treatment
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* Other: Respiratory resistor


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy volunteers Exclusion Criteria: pregnancy lactating any regular or acute use of medicine

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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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: Respiratory resistor|The volunteers are breathing through the four respiratory resistors (inspiratory, expiratory, combined in- and expiratory and no resistor) in order to increase the intrathoracic pressure svings|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Systolic pressure variation (SPV) | Relative difference between systolic blood pressure during inspiration and expiration. Meassured in percent. | Two minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Central volume deficit, Head-up tilt, Systolic pressure variation