Ultrasound Measurements of Basilica Vein Diameter at Room Air Breathing and at Positive Pressure on Healthy Volunteers

Study Overview
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Brief Summary
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Peripherally Inserted Central Catheters (PICC) and midline placement requires the catheter size to be one third of the venous diameter, or less. However, measurements during CPAP (Continous Positive Airway Pressure) might overestimate the diameter of veins in patients requiring a PICC line. The investigators will enroll 28 healthy subjects to measure their basilica vein diameter at atmospheric pressure and at 10 cmH2O of Positive End-Expiratory Pressure (PEEP). PEEP will be applied through a CPAP helmet with the straps placed under the arms or tied to the bed. The investigators will test the hypothesis that positive airway pressure significantly increases vein diameter. Under this hypothesis, the indication of avoiding catheters larger than one third of the vein diameter should be revised, as venous enlargement during PEEP may lead to the placement of inappropriately large catheters.

Detailed Description
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After consent, the investigators will enroll 28 participants, randomized with a 1:1:1:1 ratio (sealed envelope) to one of the following groups: A) Room air -> CPAP (armpit straps) -> CPAP (w/o straps) B) Room air -> CPAP (w/o straps) -> CPAP (armpit straps) C) CPAP (armpit straps) -> CPAP (w/o straps) -> Room air D) CPAP (w/o straps) -> CPAP (armpit straps) - > Room air The investigators will exclude from the study participants with an ASA score (American Society of Anesthesiology) of 3 or more, subjects with a BMI lower than 20 or with a history of pneumothorax or venous thrombosis. Investigators will enroll adult patients only (age > 18). The primary endpoint is the evaluation of a clinically significant change in venous diameter in subjects breathing at room air or during positive pressure support. The investigators decided to deliver CPAP through a CPAP Helmet, as this device is noninvasive, very weill tolerated and widely used at the study hospital. CPAP Helmet are provided with armpit straps. Secondary endpoints are the evaluation of venous flow-velocity changes and the influence of placing the helmet straps under the armpits on venous flow dynamics (venous diameter, flow-velocity). The study is composed of three steps of 5 minutes each. At each step, the investigators will use ultrasound to measure the diameter of basilica vein and venous flow-velocity at the right mid arm, while recording basic vital signs (heart rate, non-invasive blood pressure, pulsoximetry). The investigators will also gather basic biometric data (age, weight, height, gender). At room air, no intervention is given: after 5 minutes, vital signs are collected and the ultrasound measurements performed (basilica vein diameter, venous blood flow-velocity). At CPAP (armpit straps), the subjects will wear a CPAP helmet and receive 10 cmH2O of PEEP (positive end-expiratory pressure), with the helmet straps placed under the subjects' armpit: after 5 minutes, vital signs are collected and the ultrasound measurements performed (basilica vein diameter, venous blood flow-velocity). At CPAP (w/o straps), the helmet is tied to the subjects' bed: after 5 minutes, vital signs are collected and the ultrasound measurements performed (basilica vein diameter, venous blood flow-velocity).

Official Title
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Continuous Positive Airway Pressure (CPAP) Influence on the Evaluation of Basilica Vein Diameter for Catheter Implantation.

Conditions
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Ventilation Therapy; Complications

Intervention / Treatment
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* Device: CPAP


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA 1 or 2 BMI > 20 Exclusion Criteria: History of pneumothorax History of venous thrombosis

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

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Interventional cross-over study.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: A<br>Investigators will evaluate the diameter of the basilica vein and venous flow-velocity after 5 minutes of breathing at room air. Investigators will collect basic vital parameters (heart rate, blood pressure, pulsoximetry). Afterwards, the investigators will administer CPAP through a helmet, with the straps placed under the armpits. After 5 minutes, the investigators will collect again ultrasound data (venous diameter of basilica vein, flow-velocity) and basic vital parameters (heart rate, blood pressure, pulsoximetry). Then the CPAP helmet will be tied to the bed and the armpit straps removed. After 5 minutes the investigators will collect ultrasound data and basic vital parameters as in the steps before (venous diameter, flow-velocity, heart rate, blood pressure, pulsoximetry). After this three steps, the protocol ends. | Device: CPAP<br>* Application of PEEP (positive end-expiratory pressure) through a CPAP Helmet with a set PEEP of 10 cmH2O. It is a very well tolerated and noninvasive device commonly used for ventilatory support.<br>|
| Other: B<br>Same interventions and measurements as A, in different order (breathing room air, then with a CPAP helmet tied to the bed, then with a CPAP helmet fastened with armpit straps). | Device: CPAP<br>* Application of PEEP (positive end-expiratory pressure) through a CPAP Helmet with a set PEEP of 10 cmH2O. It is a very well tolerated and noninvasive device commonly used for ventilatory support.<br>|
| Other: C<br>Same interventions and measurements as A, in different order (breathing with a CPAP fastened with armpit straps, breathing with a CPAP helmet tied to the bed and breathing at room air). | Device: CPAP<br>* Application of PEEP (positive end-expiratory pressure) through a CPAP Helmet with a set PEEP of 10 cmH2O. It is a very well tolerated and noninvasive device commonly used for ventilatory support.<br>|
| Other: D<br>Same interventions and measurements as A, in different order (breathing with a CPAP helmet tied to the bed, breathing with a CPAP helmet fastened with armpit straps and breathing at room air). | Device: CPAP<br>* Application of PEEP (positive end-expiratory pressure) through a CPAP Helmet with a set PEEP of 10 cmH2O. It is a very well tolerated and noninvasive device commonly used for ventilatory support.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Venous diameter | Changes in diameter of the basilica vein (mm) in subjects breathing at room air or breathing at 10 cmH2O of positive end expiratory pressure | 15 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Flow-velocity | Changes in venous flow-velocity of the basilica vein (cm/sec) in subjects breathing at room air or breathing at 10 cmH2O of positive end-expiratory pressure | 15 min | 
| Venous diameter | Changes in venous diameter (mm) in subjects breathing with a CPAP helmet fastened with the straps under the armpits or with the CPAP helmet tied to the bed instead. | 15 min | 
| Flow-velocity | Changes in venous flow-velocity (cm/sec) in subjects breathing with a CPAP helmet fastened with the straps under the armpits or with the CPAP helmet tied to the bed instead. | 15 min |