A ssessment of an Earlobe Arterialized Blood Collector for use in Microgravity

AAssessment of an Earlobe Arterialized ssessment of an Earlobe Arterialized Blood Collector for use in MicrogravityBlood Collector for use in Microgravity

Thais Russomano* Thais Russomano* Marlise A dos Santos* Marlise A dos Santos*

João Castro* João Castro* John Whittle** John Whittle** Simon Evetts** Simon Evetts** John Ernsting** 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


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


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


The skin is then cleaned with an alcohol swab and a small incision is made in the earlobe.

Introduction



Blood is collected anaerobically via capillary tubes.

Introduction



Blood is collected anaerobically via capillary tubes.

Blood is then analyzed using a blood gas analyzer.

Introduction

Earlobe massage

Earlobe arterialized blood collection

Characteristic Radial Artery Sample

Hyperemic Earlobe Sample

Discomfort Painful Pain Free

Potential Complications

Hematoma Hemorrhage

Infection (systemic) Wrist pain

Arterial Spasm

Hemorrhage Infection (cutaneous)

Ease of Use Requires trained medical personnel

Performed by non-medical personnel.

Potential Usage Hospital based research

Hospital, clinic, rural center and university research.Aero medical and transport use. ISS and other space missions.

Radial Artery / Arterialised Earlobe Collection





Hematoma Hemorrhage


Arterial Spasm










Hematoma Hemorrhage


Arterial Spasm










Hematoma Hemorrhage


Arterial Spasm










Hematoma Hemorrhage


Arterial Spasm






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


Six healthy subjects breathed a gas mixture of 12.8% O2 in N2 (equivalent to breathing air at 12,000 feet) during 15 min of head-down tilt.

Method


Six healthy subjects breathed a gas mixture of 12.8% O2 in N2 (equivalent to breathing air at 12,000 feet) during 15 min of head-down tilt.

The blood samples were analyzed immediately.

Method

MethodHead Down Tilt to partially replicate the

effects of microgravity

Results

Blood Gas Data for Simultaneous Radial Artery and Earlobe Arterialized Blood Samples

Radial arteryMean SD (range)

Arterialized EarlobeMean SD (range)

pH(pH Unit)

7.43 0.02 (7.4 – 7.46) 7.43 0.02 (7.4 – 7.46)

PO2

(mmHg)

42.1 3.66 (38 – 47) 42.9 3.88 (37 – 50)

PCO2

(mmHg)

34.1 1.88 (31 – 37) 33.12 2.38 (29 – 37)

SaO2

(%)

79.0 3.85 (75 – 84.5) 79.9 3.29 (74 –85.6)

Results




pH(pH Unit)

7.43 0.02 (7.4 – 7.46) 7.43 0.02 (7.4 – 7.46)

PO2

(mmHg)

42.1 3.66 (38 – 47) 42.9 3.88 (37 – 50)

PCO2

(mmHg)

34.1 1.88 (31 – 37) 33.12 2.38 (29 – 37)

SaO2

(%)

79.0 3.85 (75 – 84.5) 79.9 3.29 (74 –85.6)

Results




pH(pH Unit)

7.43 0.02 (7.4 – 7.46) 7.43 0.02 (7.4 – 7.46)

PO2

(mmHg)

42.1 3.66 (38 – 47) 42.9 3.88 (37 – 50)

PCO2

(mmHg)

34.1 1.88 (31 – 37) 33.12 2.38 (29 – 37)

SaO2

(%)

79.0 3.85 (75 – 84.5) 79.9 3.29 (74 –85.6)

Results




pH(pH Unit)

7.43 0.02 (7.4 – 7.46) 7.43 0.02 (7.4 – 7.46)

PO2

(mmHg)

42.1 3.66 (38 – 47) 42.9 3.88 (37 – 50)

PCO2

(mmHg)

34.1 1.88 (31 – 37) 33.12 2.38 (29 – 37)

SaO2

(%)

79.0 3.85 (75 – 84.5) 79.9 3.29 (74 –85.6)

Results




pH(pH Unit)

7.43 0.02 (7.4 – 7.46) 7.43 0.02 (7.4 – 7.46)

PO2

(mmHg)

42.1 3.66 (38 – 47) 42.9 3.88 (37 – 50)

PCO2

(mmHg)

34.1 1.88 (31 – 37) 33.12 2.38 (29 – 37)

SaO2

(%)

79.0 3.85 (75 – 84.5) 79.9 3.29 (74 –85.6)

Results

The mean difference in PO2 between arterialized earlobe and arterial samples was 0.25 ( ± 1.25) mmHg.

Results


Comparison of PCO2 of the arterialized earlobe and arterial samples showed a mean difference of -1 ( ± 0.75) mmHg.

Results


Comparison of PCO2 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 = 0.97 r = 0.92

Discussion

Arterilaized Capillary- Arterial Mean ( SD)

PO2

mmHg

PCO2

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)

-0.72(1.67)

1.0(1.91)

Dar et al. (1995) (n=55)

0.675(4.43)

0.75(2.25)

Present study (n=6)

0.25(1.25)

-1.0(0.75)

Study Author

Discussion


PO2

mmHg

PCO2


(1965) (n=16)

0.62(4.1)

1.05(1.6)


2.09(2.48)

0.65(1.2)


-0.72(1.67)

1.0(1.91)

Dar et al. (1995) (n=55)

0.675(4.43)

0.75(2.25)

Present study (n=6)

0.25(1.25)

-1.0(0.75)

Study Author

Discussion


PO2

mmHg

PCO2


(1965) (n=16)

0.62(4.1)

1.05(1.6)


2.09(2.48)

0.65(1.2)


-0.72(1.67)

1.0(1.91)

Dar et al. (1995) (n=55)

0.675(4.43)

0.75(2.25)

Present study (n=6)

0.25(1.25)

-1.0(0.75)

Study Author

Discussion


PO2

mmHg

PCO2


(1965) (n=16)

0.62(4.1)

1.05(1.6)


2.09(2.48)

0.65(1.2)


-0.72(1.67)

1.0(1.91)

Dar et al. (1995) (n=55)

0.675(4.43)

0.75(2.25)

Present study (n=6)

0.25(1.25)

-1.0(0.75)

Study Author

Discussion


PO2

mmHg

PCO2


(1965) (n=16)

0.62(4.1)

1.05(1.6)


2.09(2.48)

0.65(1.2)


-0.72(1.67)

1.0(1.91)

Dar et al. (1995) (n=55)

0.675(4.43)

0.75(2.25)

Present study (n=6)

0.25(1.25)

-1.0(0.75)

Study Author

Discussion


PO2

mmHg

PCO2


(1965) (n=16)

0.62(4.1)

1.05(1.6)


2.09(2.48)

0.65(1.2)


-0.72(1.67)

1.0(1.91)

Dar et al. (1995) (n=55)

0.675(4.43)

0.75(2.25)

Present study (n=6)

0.25(1.25)

-1.0(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.


• Anaesthetic is not required.

Discussion

Points of note.



• Anaerobic blood collection is possible.

Discussion

Points of note.



• Anaerobic blood collection is possible.

• EAB Collector prevents environmental contamination.

Conclusion

This limited study suggests that:

Conclusion


1. Arterialized blood sampled from the earlobe provides accurate estimations of arterial blood measurements of PO2, PCO2 and pH during microgravity simulation and in hypoxia.

Conclusion


1. Arterialized blood sampled from the earlobe provides accurate estimations of arterial blood measurements of PO2, PCO2 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.

Thank you for listening

Questions?

Professor Thais Russomano

[email protected]

[email protected]

Results

Individual Data

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A ssessment of an Earlobe Arterialized Blood Collector for use in Microgravity

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