An assessment of the feasibility and effectiveness of a method of performing cardiopulmonary

resuscitation during microgravity.

Simon N Evetts, Lisa M Evetts, T Russomano,

J Castro and J Ernsting CB OBE.Microgravity Laboratory, PUCRS, Porto Alegre, Brazil.

Human Physiology and Aerospace Medicine Group, King’s College London.

Background

CPR in microgravity. Current procedures

– Restrained.– Unrestrained.

Need for effective unaided, single person CPR in space.

Recent and current CPR guidelines

European Resuscitation Council 1998:– Mouth-to-mouth ventilation requiring tidal volumes of

400 – 500 ml.

– Chest compression depth of 40 – 50 mm.

– Chest compression rate of ~ 100 compressions.min-1.

European Resuscitation Council 2001:– Tidal volumes of 700 – 1000 ml.

– Chest compression depth of 40 – 50 mm.

– Chest compression rate in excess of 100 min-1.

Evetts, Russomano, Castro CPR Method.

Human subject in microgravity (position only).

ERC Method.

Human subject in microgravity (position only).

ERC Method.

Manikin use in microgravity (position and CPR).

Study Method

Subjects/investigators. Laerdal CPR Manikin adaptation. Pre & post flight procedures. In flight procedures. Measurements.

Results

Measure +1GZ MicrogravityChest Compressions     Depth (mm) 43.6 ± 0.59 41.3 ± 1.03 Range (min-max, mm) 40.4 – 47.1 27.6 – 51.2 Rate (compressions.min-1) 97.1 ± 3.0 80.2 ± 3.4 Percent correct (depth) 90% 60% n 225 672Volume     Volume (ml) 507.6 ± 11.5 491 ± 50.4 Range (min-max, ml) 423 – 570 284 - 891 Percent correct 87% 69% n 30 32

Results

Measure +1GZ MicrogravityChest Compressions     Depth (mm) 43.6 ± 0.59 41.3 ± 1.03 Range (min-max, mm) 40.4 – 47.1 27.6 – 51.2 Rate (compressions.min-1) 97.1 ± 3.0 80.2 ± 3.4 Percent correct (depth) 90% 60% n 225 672Volume     Volume (ml) 507.6 ± 11.5 491 ± 50.4 Range (min-max, ml) 423 – 570 284 - 891 Percent correct 87% 69% n 30 32

Results

Measure +1GZ MicrogravityChest Compressions     Depth (mm) 43.6 ± 0.59 41.3 ± 1.03 Range (min-max, mm) 40.4 – 47.1 27.6 – 51.2 Rate (compressions.min-1) 97.1 ± 3.0 * 80.2 ± 3.4 * Percent correct (depth) 90% 60% n 225 672Volume     Volume (ml) 507.6 ± 11.5 491 ± 50.4 Range (min-max, ml) 423 – 570 284 - 891 Percent correct 87% 69% n 30 32

* P < 0.05

Results

Measure +1GZ MicrogravityChest Compressions     Depth (mm) 43.6 ± 0.59 41.3 ± 1.03 Range (min-max, mm) 40.4 – 47.1 27.6 – 51.2 Rate (compressions.min-1) 97.1 ± 3.0 * 80.2 ± 3.4 * Percent correct (depth) 90% 60% n 225 672Volume     Volume (ml) 507.6 ± 11.5 491 ± 50.4 Range (min-max, ml) 423 – 570 284 - 891 Percent correct 87% 69% n 30 32

Discussion

Reasons for insufficient rate of chest compression and greater variation of measures in microgravity.– Novelty of environment.– Variable acceleration forces.– Shortness of microgravity exposure.– Degree of manikin reliability.

ERC compared to other methods of performing CPR in microgravity.

Current unpublished findings. Further research required:

– Effects of training and expertise.– Effects of strength.– Effects of anthropometric indices.

Discussion

Effectiveness of the ERC method for all populations will need to be ascertained before it can be considered a viable method.

CPR of this nature is more difficult than at +1GZ and will therefore require appropriate pre-mission training.

Preliminary results indicate that the ERC method of unaided, single person CPR in microgravity is likely to be viable for use in space.

Conclusion