Does Circumferential Negative Pressure Therapy Impair Distal O2 Saturation?

Does Circumferential Negative Pressure Therapy Impair Distal O2 Saturation? A Randomized Controlled Study

Abstract: Background: Circumferential negative pressure wound therapy (CNPWT) is commonly used to manage wounds and enhance the healing process. A theoretical concern was recently raised that CNPWT may have a negative effect on perfusion distally. Objectives: We aim to evaluate the effect of circumferential negative pressure therapy (CNPT) on distal O2 saturation in healthy volunteers. Design: Randomized controlled non-inferiority study. Methods: Fourteen healthy adult volunteers with O2 saturation ≥95% (by index finger pulse oximetry) will be invited to participate in the study. After obtaining a written informed consent, CNPWT foam/dressing will be applied in a sandwich-like manner on the middle third of each arm and a negative intermittent pressure of 125 mmHg will be applied to one arm chosen randomly, using the contralateral arm as control. The pressure will be applied 5 minutes on and 2 minutes off for 9 hours. Individual's participation will be terminated if O2 saturation drops below 92% at any study time. The outcome measure is index finger O2 saturation and will be checked every 30 minutes using a pulse oximetry. The area under the curve (AUC) of O2 saturation in the 2 arms will be compared using ANCOVA. Sample size was calculated to have 90% power, assuming a type one error of 5%, non-inferiority margin of 24 (mean AUC difference), SD of 20, and drop out of 2 participants. Importance: The study is expected to provide conclusive evidence on the effect of intermittent CNPT on distal O2 saturation. The results would have direct implications for CNPWT.

The aim of this study is to evaluate the effect of circumferential negative pressure therapy (CNPT) on distal O2 saturation in healthy volunteers. Design and Methodology: Design: This is a randomized controlled non-inferiority study. Recruitment: Volunteers will be recruited through advertisement in King Faisal Specialist Hospital & Research Centre and other hospitals in Riyadh. Pre-study procedures: After obtaining a well documented medical history each volunteer will undergo a full physical examination as well as an in-depth upper limb examination and comprehensive evaluation (including a pre-study index finger O2 saturation and upper limbs circumference measurements), the following data will be also collected: age, sex, height&weight, body mass index, and vital signs. Procedures: CNPWT foam and dressing (in accordance to manufacturer's instructions) will be applied in a sandwich-like manner on the middle third of each arm, and a negative intermittent pressure of 125 mmHg will be applied to one arm chosen randomly, using the contralateral arm as control. The pressure will be applied 5 minutes on and 2 minutes off for 9 hours. Individual's participation will be terminated if O2 saturation by pulse oximetry drops below 92% at any study time. Statistical analysis: The area under the curve (AUC) of O2 saturation will be compared between the 2 arms using ANCOVA. Randomization schedule: a randomization schedule will be generated by an online program (www.randomization.com). Block randomization will be used. Sample size: Fourteen adult volunteers will be invited to participate in the study. The sample size for the study was calculated to have 90% power, assuming a type one error of 5%, non-inferiority margin of 24 (mean AUC difference), SD of 20, and drop out of 2 participants.

2 groups: intervention and control (both are in each arm of the same participant). Intervention will be applied at one arm (chosen randomly) with using the contralateral arm as a control.

Negative pressure system is applied with negative pressure (Active) at a participant's unilateral arm

Negative pressure system is applied without negative pressure (Inactive) at a participant's contralateral arm

Negative Pressure System is a non-invasive system that applies sub-atmospheric(Negative) pressure, through a foam and an air-tight film dressing which is connected by suction tubes to a controller unit by which the primary negative pressure can be adjusted.

Index finger O2 saturation will be checked every 30 minutes using a pulse oximetry, from zero hour of the study until the end of the 9th hour, then AUC will be calculated.

Inclusion Criteria: Healthy adult volunteers with O2 saturation ≥95% by pulse oximetry. Potential volunteers will be screened by routine medical history and physical examination and an in-depth upper limb examination Exclusion Criteria: Unhealthy individual Chronic conditions History of upper limb diseases or defects. History of upper limb Surgical intervention. History of upper limb implants. Pre-study O2 saturation in either indices of less than 95% Congenital or Traumatic upper limb defect

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