Liexin Liu, Frank Beckers, Bart Verheyden, Kurt Couckuyt , André Aubert

中国宇航员太空飞行后心脏自主功能分析

Autonomic control after spaceflight 2005

Laboratory of Experimental CardiologyUniv. Hospital Gasthuisberg, & Interdisciplinary Centerfor Space Studies (ICSS), K.U.Leuven, Leuven, Belgium

Wan Hu (16th cent Ming Dynasty)He had a chair built with forty-seven rockets attached. On the day of lift-off, Wan, splendidly attired, climbed into his rocket chair and forty seven servants lit the fuses and then hastily ran for cover. There was a huge explosion. When the smoke cleared, Wan and the chair were gone. He was never seen again.

背景情况Background

Cardiovascular Adaptation & Deconditioning

Cardiovascular system resting - No effort for moving- No liquid transfer- No flow redistribution- No stimulation of 1G reflexes

When returning to 1G redistribution of flow towards brain less efficient risk for syncope

• Autonomic cardiovascular control before, during and after space flight– ECG and BP measurements– Respiration– Induce changes: head flexion

• Orthostatic intolerance – Stand test

Experiment science objectives

Simplified scheme

Brains

Heart ratecardiac outputBlood pressure

Parasympathetic(vagal)

sympathetic

+ -

Model of cardiovascular regulation

Neurocardiovasclar Regulation of Blood Pressure

BRAIN STEMsymp para

VASOMOTOR TONE HEART RATE

BLOOD PRESSURE

COTPR

arterial baroreceptors

n. vagus

SV

-

-+ + + (-)

+-

BAROREFLEX

()

Heart Rate VariabilityBlood Pressure Variability

Baroreflex Sensitivity

Model of cardiovascular variability

• Baroreceptor• Chemoreceptor• Atrial stretch receptors• Position (supine, standing)• Interventions:

– Respiration– Valsalve– Carotis massage– Stress (Gravity…)– …

HRV, BPV are influenced by:

HRV and BPV indices can be used to quantify autonomic cardiovascular modulation

从心电、血压到心率变异、血压变异及压力反射敏感性

From HR & BP to HRV, BPV & BRS

研究方法Method

Ground BDC’s / postflight

Experiment Hardware

• ECG (electrocardiogram)• BP (continuous blood pressure)• Respiration with pressure sensor

Parameters

816 848 784 832 864 800 704 976 880 768 800 944

120 117 115 120 122 119 119 120 115 109 113 115 112

( ms )

( mmHg )

Time

Heart Rate Variability & Blood Pressure Variability

BP(mmHg)

Time

HRVHRV BPVBPVBRSBRS

RR RR RR RR

ECG

HRV & BPV

分析方法Analysis

频域分析Frequency Analysis

FFT

HRV:

• Low Frequency power (LF) [0.04-0.15 Hz] ~ sympathetic modulation + BRS+ Vagal modulation

• High Frequency power (HF) [0.16-0.4 Hz] ~ vagal modulation

• Total power [0.0078-0.5 Hz] ~ global autonomic modulation

BPV:

• Low Frequency power (LF) [0.04-0.15 Hz] ~ sympathetic modulation

• High Frequency power (HF) [0.16-0.4 Hz] ~ mechanical effect of respiration

Tachogram & Systogram

• Calculation of the slope between dynamic HR responses to systolic BP changes: index of dynamic baroreflex sensitivity (BRS)– Sequence method: at least 3 sequences– Other methods: alpha method, statistical dependency, cross

correlation…770,0

440,8

500,0

550,0

600,0

650,0

700,0

151,893,8 100,0 105,0 110,0 115,0 120,0 125,0 130,0 135,0 140,0 145,0

RR

BP

Algorithms to evaluate cardiovascular autonomic function - Baroreflex sensitivity (BRS)

Heart Rate (ESA)

5245535555N =

R+25R+19R+15R+9R+4R+2R+1FD 8FD 5L-30

HF

Pow

er

(ms²)

700

600

500

400

300

200

100

0

5245535555N =

R+25R+19R+15R+9R+4R+2R+1FD 8FD 5L-30

LF

Po

we

r (m

s²)

4000

3000

2000

1000

0

Sympathetic modulationSympathetic modulation Vagal modulationVagal modulation

Beckers et al. J Gravit Phys, 2003

Results HRV standing

5245535554N =

R+25R+19R+15R+9R+4R+2R+1FD 8FD 5L-30

BR

S (

ms/

mm

Hg) 16

14

12

10

8

6

4

2

Baroreflex sensitivity

中国航天员研究Chinese Astronauts Study 2005

Putting offEquipment

Putting onEquipment

supine

standing

sitting Check cables, check signals

BASELINE

10 min

FREQ_1 FREQ_2

5 min 5 min

BASELINE FREQ_1

10 min

FREQ_2

5 min 5 min

FLEXION

1 min

Freq1 : 5 seconds breathing in – 5 seconds breathing out

Freq2 : 3 seconds breathing in – 3 seconds breathing out

Rec

ord

ing

1R

eco

rdin

g 2

China experimental protocol

结果Result

心率变异HRV

HR

Supine: heart rate decreases, stabilized at R+7

Standing: heart rate remains similar

Astronaut 1 Base

405060708090

100

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

HR

(bea

t/min

)

Stand

Supine

Astronaut 2 Base

405060708090

100

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

HR

(bea

t/min

)Stand

Supine

-23% -12%

LFSupine: increase post-flight with stabilization at R+7

Astronaut 1 Base

0500

10001500200025003000

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF p

ower Supine

Stand

Astronaut 2 Base

0500

10001500200025003000

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF p

ower Supine

Stand

+312% -6%

LF%

Astronaut 1 Base

0

50

100

150

200

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF% Supine

Stand

Astronaut 2 Base

0

50

100

150

200

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF% Supine

Stand

-13% -27%

Supine: small decrease, but most likely not significant

HF

Supine: increase postflight with stabilization at R+7

Astronaut 1 Base

0

400

800

1200

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

HF

pow

er Supine

Stand

Astronau 2 Base

0

400

800

1200

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

HF

pow

er Supine

Stand

+218% +145%

HF%

Astronaut 1 Base

0

10

20

30

40

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

HF%

Supine

Stand

Astronaut 2 Base

0

10

2030

40

50

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

HF%

Supine

Stand

-33% +90%

HF% shows contrasting evolution between astronauts

LF/HF

Astronaut 1 Base

0

10

2030

40

50

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF/H

F Supine

Stand

Astronaut 2 Base

0

10

20

30

40

50

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF/H

F Supine

Stand

+30% -62%

Stable post-flight (high percentages due to low values)

血压变异BPV

BP

Astronaut 1 Base

0

60

120

180

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

BP

(mm

Hg)

Stand

Supine

Astronaut 2 Base

0

60

120

180

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

BP

(mm

Hg)

Stand

Supine

After space flight, in both astronauts SBP had no obvious alteration at supine position, as well as at stand position.

-1% +27%

LF

Astronaut 1 Base

0

60

120

180

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF p

ower Stand

Supine

Astronaut 2 Base

0

60

120

180

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

LF p

ower Stand

Supine

Supine: increase immediately post-flight, but rather fast normalization

+104% +340%

压力反射敏感性BRS

BRS

Astronaut 1 Base

0

6

12

18

24

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

BR

S Supine

Stand

Astronaut 2 Base

0

6

12

18

24

21dbeforeflight

2d afterflight

3d afterflight

5d afterflight

7d afterflight

9d afterflight

Flight Date

BR

S Supine

Stand

+44% -12%

Rather stable evolution post-flight

Results：

• In the Chinese group there was no difference in pre- and post-flight HRV parameters

• Similar differences after 10 day flights of ESA and Russian cosmonauts were between 13% and 54%.

• No evolution until R+9. • Similar behavior was observed for BPV

parameters.

结论Conclusion

Conclusion：

• No significant differences were found between pre and post flight in the Chinese group in contrast to the ESA/Russian group

• No evolution post-flight until R+9 in the Chinese group

• This different behavior could be due to specific training methods and/or nutrition methods?

初步结果：

• 在短期航天飞行后，中国宇航员的心血管自主神经功能变化情况与俄罗斯宇航员、欧洲宇航员存在着明显的差异。

• 中国宇航员经过 5天的短期太空飞行返回地面后，心率、血压稳定；迷走神经张力有一过性升高。

可能因素：

• 太空飞行时间短。目前欧洲、美国的短期载人航天飞行一般都在 10天左右。以前的研究结果大多数都是建立在这个时间基础上的。

• 训练水平高。也许因为中国航天员的训练方法更加有效。

• 药物因素。太空飞行结束后，服用中药可能对航天员的心血管功能恢复有帮助。

• 基因差异。

相关问题：

• 返回 10天之后，是否还继续监测心电图和血压情况？情况怎样？

• 杨利伟的飞行时间更短，是否可以做一参照，对其血压、心率及心脏自主神经功能进行回顾性的研究？

• 两名航天员的飞行前后体重情况？• 应对另外 4个航天员的基础检测数据进行参照分析，已得到基础情况，以便进行统计学分析。