Assessing the safety of the Cardiac Return Air Blanket (CRAB) on healthy volunteers

The Cardiac Return Air Blanket (CRAB) is an inflatable blanket, which is positioned over the abdomen and upper legs of the patient and held in position by 3 Velcro hook straps which pass under the table and adhere to 3 sections of Velcro loops onto the blanket. The air blanket is inflated by a battery powered, computer controlled, electric air pump. The blanket evenly compresses the abdomen and upper legs to physically squeeze the venous blood of the lower body to the upper body, increasing the Central Venous Pressure (CVP). The participant will present at the allotted time to study room at Sir Charles Gairdner Hospital. A research nurse will re-confirm participant consent and answer any questions (or escalate to the Chief Principal Investigator (CPI), enter the demographic data, and confirm the inclusion / exclusion criteria have been met. A urinary pregnancy test will be offered to any females unsure if they are pregnant. The participant will lie flat on a narrow hospital trolley or operating theatre bed. The non-invasive monitoring placed on the participant will include: • 3 lead ElectroCardioGram (ECG) – continuous reading of Lead II, giving Heart rate (HR), and rhythm • Non-Invasive Blood Pressure (BP) –2 minutely recordings • Pulse Oximetry (SaO2)– continuous reading of oxygen saturations. If the participant has any exposed skin between chest and knees a sheet will be placed over the participant’s body. The CRAB blanket will be placed on the patient with the top of the blanket (orange strap just below the xiphisternum and secured with the Velcro straps. The lower edge of the blanket will reach the knees or below. The CRAB Pump will then be attached to the CRAB blanket and turned on. The participant will be reminded they can have the protocol stopped at any stage. • Baseline HR, BP and SaO2 will be recorded. • When both the participant and the equipment are ready, the research nurse will start the timer and pressurised the CRAB to 20cm H20. • One minute after inflation – HR, BP and SaO2 will be recorded. • Two minutes after inflation the research nurse will check if the participant consents to the increased pressure. If the participant is consenting the CRAB will be pressurised to 40cm H20 (Full pressure). • One minute after the increase in pressure– HR, BP and SaO2 will be recorded. • Two minutes after the increase in pressure the CRAB pressure will be reduced to zero and the CRAB removed • The research nurse will check if the participant has any residual symptoms. If the participant is symptom free the monitoring will be removed. Participants will then be asked to complete the following questionnaire. Questionnaire For the CRAB at the lower pressure 1) Rate the discomfort of the CRAB: 0-to-10: 0 No discomfort – 10 Extreme discomfort 2) Did you have pain in any location Y / N a. If yes: where was the pain b. If yes: rate the pain: 0-to-10: 0 No pain, 10 Extreme pain 3) Rate the difficulty of breathing: 0-to-10: 0 No difficulty – 10 Extreme difficulty For the CRAB at the higher pressure 1) Rate the discomfort of the CRAB: 0-to-10: 0 No discomfort – 10 Extreme discomfort 2) Did you have pain in any location Y / N a. If yes: where was the pain b. If yes: rate the pain: 0-to-10: 0 No pain, 10 Extreme pain 3) Rate the difficulty of breathing: 0-to-10: 0 No difficulty – 10 Extreme difficulty After the CRAB deflated were there any residual effects 1) Discomfort a. Y/N b. If yes - Rate the residual discomfort of the CRAB: 0 No discomfort – 10 Extreme discomfort 2) Did you have any residual pain in any location a. Y / N b. If yes: where was the pain c. If yes rate the pain: 0-to-10: 0 No pain - 10 Extreme pain 3) Did you have any residual difficulty of breathing a. Y/N b. Rate the difficulty of breathing: 0-to-10: 0 No difficulty – 10 Extreme difficulty 4) Any changes in your skin due to the CRAB a. Y/N b. If yes – Details Additional comments about the effects of the CRAB: Free text. Follow-up If the participant is symptom free / no residual effects after deflation of the CRAB, then no further participant follow-up will be required. Any participant who has residual symptoms will be monitored for a further 20minutes. If the participant continues to have residual symptoms, this will be classed as an Adverse Event, and an adequate plan will be made for their symptoms by the PI. This may include follow-up phone calls, medical referral or in unlikely serious circumstances transfer to the emergency department or medical emergency response team call. All participants who have required ongoing monitoring or referral of symptoms will be followed up 30 days post device testing to determine whether symptoms have been resolved or have resulted in ongoing treatment and/or management. The method of this follow-up will be determined by the PI and the participant at the time of the event. All participants will be supplied with contact detail trial team. They will be encouraged to contact trial team to raise any concern regarding the trial or to report any comments that they feel may be relevant.