Assessment of an Earlobe Arterialized Blood Collector for use in Microgravity Thais Russomano* Marlise A dos Santos* João Castro* John Whittle** Simon Evetts** John Ernsting** *Microgravity Laboratory/IPCT-PUCRS, Brazil **Aerospace Medicine Group, King´s College London, UK

There is currently no method of directly measuring arterial blood gas tensions in space. Background

There is currently no method of directly measuring arterial blood gas tensions in space. An alternative to direct arterial measurement is earlobe arterialized blood sampling, an accurate technique for measuring blood gas tensions, which has been in use in clinical medicine and physiology for more than 30 years (Lilienthal JL & Riley RL, 1944). Background

There is currently no method of directly measuring arterial blood gas tensions in space. An alternative to direct arterial measurement is earlobe arterialized blood sampling, an accurate technique for measuring blood gas tensions, which has been in use in clinical medicine and physiology for more than 30 years (Lilienthal JL & Riley RL, 1944). This technique has not yet been examined in the microgravity environment due to the risk of environmental contamination with blood products. Background

The aim of the project is to develop a device and associated procedures that enable an acceptable estimation of arterial blood gas tensions and pH to be conducted accurately and safely in microgravity. Aim

Introduction Earlobe Blood Sampling – The Technique

Introduction Earlobe Blood Sampling – The Technique The earlobe is rendered hyperemic by the application of a rubefacient cream containing 1% methyl nicotinate.

Introduction Earlobe Blood Sampling – The Technique The earlobe is rendered hyperemic by the application of a rubefacient cream containing 1% methyl nicotinate. The skin is then cleaned with an alcohol swab and a small incision is made in the earlobe.

Introduction Earlobe Blood Sampling – The Technique The earlobe is rendered hyperemic by the application of a rubefacient cream containing 1% methyl nicotinate. The skin is then cleaned with an alcohol swab and a small incision is made in the earlobe. Blood is collected anaerobically via capillary tubes.

Introduction Earlobe Blood Sampling – The Technique The earlobe is rendered hyperemic by the application of a rubefacient cream containing 1% methyl nicotinate. The skin is then cleaned with an alcohol swab and a small incision is made in the earlobe. Blood is collected anaerobically via capillary tubes. Blood is then analyzed using a blood gas analyzer.

Introduction Earlobe massage Earlobe arterialized blood collection

CharacteristicRadial Artery Sample Hyperemic Earlobe Sample DiscomfortPainfulPain Free Potential Complications Hematoma Hemorrhage Infection (systemic) Wrist pain Arterial Spasm Hemorrhage Infection (cutaneous) Ease of UseRequires trained medical personnel Performed by non- medical personnel. Potential UsageHospital based research Hospital, clinic, rural center and university research. Aero medical and transport use. ISS and other space missions. Radial Artery / Arterialised Earlobe Collection

CharacteristicRadial Artery Sample Hyperemic Earlobe Sample DiscomfortPainfulPain Free Potential Complications Hematoma Hemorrhage Infection (systemic) Wrist pain Arterial Spasm Hemorrhage Infection (cutaneous) Ease of UseRequires trained medical personnel Performed by non- medical personnel. Potential UsageHospital based research Hospital, clinic, rural center and university research. Aero medical and transport use. ISS and other space missions.

CharacteristicRadial Artery Sample Hyperemic Earlobe Sample DiscomfortPainfulPain Free Potential Complications Hematoma Hemorrhage Infection (systemic) Wrist pain Arterial Spasm Hemorrhage Infection (cutaneous) Ease of UseRequires trained medical personnel Performed by non- medical personnel. Potential UsageHospital based research Hospital, clinic, rural center and university research. Aero medical and transport use. ISS and other space missions.

CharacteristicRadial Artery Sample Hyperemic Earlobe Sample DiscomfortPainfulPain Free Potential Complications Hematoma Hemorrhage Infection (systemic) Wrist pain Arterial Spasm Hemorrhage Infection (cutaneous) Ease of UseRequires trained medical personnel Performed by non- medical personnel. Potential UsageHospital based research Hospital, clinic, rural center and university research. Aero medical and transport use. ISS and other space missions.

CharacteristicRadial Artery Sample Hyperemic Earlobe Sample DiscomfortPainfulPain Free Potential Complications Hematoma Hemorrhage Infection (systemic) Wrist pain Arterial Spasm Hemorrhage Infection (cutaneous) Ease of UseRequires trained medical personnel Performed by non- medical personnel. Potential UsageHospital based research Hospital, clinic, rural center and university research. Aero medical and transport use. ISS and other space missions.

Development and Evaluation of a Earlobe Arterialized Blood Collector

Prototype of the Earlobe Arterialized Blood (EAB) Collector

Current Prototype of the EAB Collector Blade module Capillary tube module Capillary tube Body (module housing) Ophthalmic blade

A validation study of the EAB Collector was conducted in which simultaneous samples of arterial and arterialized blood were taken from the radial artery and the earlobe. Method

A validation study of the EAB Collector was conducted in which simultaneous samples of arterial and arterialized blood were taken from the radial artery and the earlobe. Six healthy subjects breathed a gas mixture of 12.8% O 2 in N 2 (equivalent to breathing air at 12,000 feet) during 15 min of head-down tilt. Method

A validation study of the EAB Collector was conducted in which simultaneous samples of arterial and arterialized blood were taken from the radial artery and the earlobe. Six healthy subjects breathed a gas mixture of 12.8% O 2 in N 2 (equivalent to breathing air at 12,000 feet) during 15 min of head-down tilt. The blood samples were analyzed immediately. Method

Head Down Tilt to partially replicate the effects of microgravity

Results Blood Gas Data for Simultaneous Radial Artery and Earlobe Arterialized Blood Samples Radial artery Mean SD (range ) Arterialized Earlobe Mean SD (range ) pH (pH Unit) (7.4 – 7.46) PO 2 (mmHg) (38 – 47) (37 – 50) PCO 2 (mmHg) (31 – 37) (29 – 37) SaO 2 (%) (75 – 84.5) (74 –85.6)

Results Blood Gas Data for Simultaneous Radial Artery and Earlobe Arterialized Blood Samples Radial artery Mean SD (range ) Arterialized Earlobe Mean SD (range ) pH (pH Unit) (7.4 – 7.46) PO 2 (mmHg) (38 – 47) (37 – 50) PCO 2 (mmHg) (31 – 37) (29 – 37) SaO 2 (%) (75 – 84.5) (74 –85.6)

Results Blood Gas Data for Simultaneous Radial Artery and Earlobe Arterialized Blood Samples Radial artery Mean SD (range ) Arterialized Earlobe Mean SD (range ) pH (pH Unit) (7.4 – 7.46) PO 2 (mmHg) (38 – 47) (37 – 50) PCO 2 (mmHg) (31 – 37) (29 – 37) SaO 2 (%) (75 – 84.5) (74 –85.6)

Results Blood Gas Data for Simultaneous Radial Artery and Earlobe Arterialized Blood Samples Radial artery Mean SD (range ) Arterialized Earlobe Mean SD (range ) pH (pH Unit) (7.4 – 7.46) PO 2 (mmHg) (38 – 47) (37 – 50) PCO 2 (mmHg) (31 – 37) (29 – 37) SaO 2 (%) (75 – 84.5) (74 –85.6)

Results Blood Gas Data for Simultaneous Radial Artery and Earlobe Arterialized Blood Samples Radial artery Mean SD (range ) Arterialized Earlobe Mean SD (range ) pH (pH Unit) (7.4 – 7.46) PO 2 (mmHg) (38 – 47) (37 – 50) PCO 2 (mmHg) (31 – 37) (29 – 37) SaO 2 (%) (75 – 84.5) (74 –85.6)

Results The mean difference in PO 2 between arterialized earlobe and arterial samples was 0.25 ( ± 1.25) mmHg.

Results The mean difference in PO 2 between arterialized earlobe and arterial samples was 0.25 ( ± 1.25) mmHg. Comparison of PCO 2 of the arterialized earlobe and arterial samples showed a mean difference of -1 ( ± 0.75) mmHg.

Results The mean difference in PO 2 between arterialized earlobe and arterial samples was 0.25 ( ± 1.25) mmHg. Comparison of PCO 2 of the arterialized earlobe and arterial samples showed a mean difference of -1 ( ± 0.75) mmHg. There was no difference between the pH values of the arterialized earlobe and arterial samples.

Correlations between Arterial and Earlobe Blood Sample Measurements r = 0.93 r = 0.94 r = 0.97r = 0.92

Discussion Arterilaized Capillary- Arterial Mean ( SD) PO 2 mmHg PCO 2 mmHg Langlands & Wallace (1965) (n=16 ) 0.62 (4.1) 1.05 (1.6) Godfrey et al. (1971) (n=8) 2.09 (2.48) 0.65 (1.2) Spiro & Dowdeswell (1971) (n=11) (1.67) 1.0 (1.91) Dar et al. (1995) (n=55) (4.43) 0.75 (2.25) Present study (n=6) 0.25 (1.25) (0.75) Study Author

Discussion Arterilaized Capillary- Arterial Mean ( SD) PO 2 mmHg PCO 2 mmHg Langlands & Wallace (1965) (n=16 ) 0.62 (4.1) 1.05 (1.6) Godfrey et al. (1971) (n=8) 2.09 (2.48) 0.65 (1.2) Spiro & Dowdeswell (1971) (n=11) (1.67) 1.0 (1.91) Dar et al. (1995) (n=55) (4.43) 0.75 (2.25) Present study (n=6) 0.25 (1.25) (0.75) Study Author

Discussion Arterilaized Capillary- Arterial Mean ( SD) PO 2 mmHg PCO 2 mmHg Langlands & Wallace (1965) (n=16 ) 0.62 (4.1) 1.05 (1.6) Godfrey et al. (1971) (n=8) 2.09 (2.48) 0.65 (1.2) Spiro & Dowdeswell (1971) (n=11) (1.67) 1.0 (1.91) Dar et al. (1995) (n=55) (4.43) 0.75 (2.25) Present study (n=6) 0.25 (1.25) (0.75) Study Author

Discussion Arterilaized Capillary- Arterial Mean ( SD) PO 2 mmHg PCO 2 mmHg Langlands & Wallace (1965) (n=16 ) 0.62 (4.1) 1.05 (1.6) Godfrey et al. (1971) (n=8) 2.09 (2.48) 0.65 (1.2) Spiro & Dowdeswell (1971) (n=11) (1.67) 1.0 (1.91) Dar et al. (1995) (n=55) (4.43) 0.75 (2.25) Present study (n=6) 0.25 (1.25) (0.75) Study Author

Discussion Arterilaized Capillary- Arterial Mean ( SD) PO 2 mmHg PCO 2 mmHg Langlands & Wallace (1965) (n=16 ) 0.62 (4.1) 1.05 (1.6) Godfrey et al. (1971) (n=8) 2.09 (2.48) 0.65 (1.2) Spiro & Dowdeswell (1971) (n=11) (1.67) 1.0 (1.91) Dar et al. (1995) (n=55) (4.43) 0.75 (2.25) Present study (n=6) 0.25 (1.25) (0.75) Study Author

Discussion Arterilaized Capillary- Arterial Mean ( SD) PO 2 mmHg PCO 2 mmHg Langlands & Wallace (1965) (n=16 ) 0.62 (4.1) 1.05 (1.6) Godfrey et al. (1971) (n=8) 2.09 (2.48) 0.65 (1.2) Spiro & Dowdeswell (1971) (n=11) (1.67) 1.0 (1.91) Dar et al. (1995) (n=55) (4.43) 0.75 (2.25) Present study (n=6) 0.25 (1.25) (0.75) Study Author

Discussion Points of note.

Discussion Points of note. Arterialized blood collection from the earlobe is virtually pain free.

Discussion Points of note. Arterialized blood collection from the earlobe is virtually pain free. Anaesthetic is not required.

Discussion Points of note. Arterialized blood collection from the earlobe is virtually pain free. Anaesthetic is not required. Anaerobic blood collection is possible.

Discussion Points of note. Arterialized blood collection from the earlobe is virtually pain free. Anaesthetic is not required. Anaerobic blood collection is possible. EAB Collector prevents environmental contamination.

Conclusion This limited study suggests that:

Conclusion This limited study suggests that: 1. Arterialized blood sampled from the earlobe provides accurate estimations of arterial blood measurements of PO 2, PCO 2 and pH during microgravity simulation and in hypoxia.

Conclusion This limited study suggests that: 1. Arterialized blood sampled from the earlobe provides accurate estimations of arterial blood measurements of PO 2, PCO 2 and pH during microgravity simulation and in hypoxia. 2. Blood collection will be possible in microgravity without environmental contamination.

Further Studies 1.To validate the EAB Collector during normoxia in other body positions (sitting and supine); 2.To test the efficiency of the EAB Collector in microgravity (parabolic flight).* * Protocol under evaluation by ESA.

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Results Individual Data