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Measurement of cerebral blood flow autoregulation with rheoencephalography: a comparative pig study

Michael Bodo
Michael Bodo
, 
Leslie D. Montgomery
Leslie D. Montgomery
, 
Frederick J. Pearce
Frederick J. Pearce
 et 
Rocco Armonda
Rocco Armonda
   | 31 déc. 2018
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Publié en ligne: 31 déc. 2018
Pages: 123 - 132
Reçu: 19 nov. 2018
DOI: https://doi.org/10.2478/joeb-2018-0017
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© 2018 M. Bodo, L.D. Montgomery, F.J. Pearce, R. Armonda published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Effect of 15 water cm PEEP. According to the CBF AR definition, here CBF AR is active and reflected by CF pulse amplitude, REG 1st derivative, its integral and ICP. CBF AR is passive in traces CF mean, LDF and CBF (quantitative CBF; unit ml/100gr/min). Both calculated CBF AR indexes (PRx from ICP and REGx from REG) show active (-1) status at the same time. Legend: SAP: systemic arterial pressure; CF pulse: carotid flow pulse; CF mean: mean CF; CBF: absolute blood flow (ml/100 g/min), numbers indicating maximum and minimum values; REG 1st d.: REG first derivative; REG 1st d. int: integral of REG 1st derivative; ICP: intracranial pressure; LDF: laser Doppler flow (brain). PRx: Person's correlation coefficient calculated from SAP and ICP; REGx: Person's correlation coefficient calculated from SAP and REG. PEEP units are in water cm. Pig ID: CBF 13, file 13:53; time window 4000-7007 s.
Effect of 15 water cm PEEP. According to the CBF AR definition, here CBF AR is active and reflected by CF pulse amplitude, REG 1st derivative, its integral and ICP. CBF AR is passive in traces CF mean, LDF and CBF (quantitative CBF; unit ml/100gr/min). Both calculated CBF AR indexes (PRx from ICP and REGx from REG) show active (-1) status at the same time. Legend: SAP: systemic arterial pressure; CF pulse: carotid flow pulse; CF mean: mean CF; CBF: absolute blood flow (ml/100 g/min), numbers indicating maximum and minimum values; REG 1st d.: REG first derivative; REG 1st d. int: integral of REG 1st derivative; ICP: intracranial pressure; LDF: laser Doppler flow (brain). PRx: Person's correlation coefficient calculated from SAP and ICP; REGx: Person's correlation coefficient calculated from SAP and REG. PEEP units are in water cm. Pig ID: CBF 13, file 13:53; time window 4000-7007 s.

Fig. 2

Polygraphic traces during CO2 inhalation. Abbreviations are as in Fig 1. RESP: respiration. As a function of CO2 increase, ICP, CBF, LDF, REG 1st derivative and SAP increased; both CF pulse amplitude and mean value decreased. Pig recording of 5/22/07; time window 85-97 min.
Polygraphic traces during CO2 inhalation. Abbreviations are as in Fig 1. RESP: respiration. As a function of CO2 increase, ICP, CBF, LDF, REG 1st derivative and SAP increased; both CF pulse amplitude and mean value decreased. Pig recording of 5/22/07; time window 85-97 min.

Fig. 3

Box diagram of Pearson's correlation coefficients between measured modalities. Recording of analog signals showed SAP decrease after 8 minutes and plateau at 40 mmHg during the rest the of recording (from 22 till 71 m); simultaneous decrease of mean CF, ICP, brain tissue O2, exhaled CO2 concentration; transient increase of CBF, CF and pulse oximeter amplitudes; REG followed SAP decrease and showed transient increase; LDF involved artifact, was unable to visually evaluate change. Pig # 1, file # 2. Input data (time points) are representing 65 min.
Box diagram of Pearson's correlation coefficients between measured modalities. Recording of analog signals showed SAP decrease after 8 minutes and plateau at 40 mmHg during the rest the of recording (from 22 till 71 m); simultaneous decrease of mean CF, ICP, brain tissue O2, exhaled CO2 concentration; transient increase of CBF, CF and pulse oximeter amplitudes; REG followed SAP decrease and showed transient increase; LDF involved artifact, was unable to visually evaluate change. Pig # 1, file # 2. Input data (time points) are representing 65 min.

Fig. 4

Polygraphic traces during hemorrhage. Mean arterial blood pressure was 40 mmHg, maintained by a computer controlled system. In the first phase of hemorrhage carotid flow pulse (Car Fl R), pulse oximeter signal (POX) and skin blood flow (Skin BF- measured by LDF; both sensors were placed on nose). REG showed compensatory amplitude increase. The involvement of various organs is represented by different traces. Traces characterize various phases of hemorrhage compensation. The transient POX amplitude increase ended when heart rate (HR) increase indicated the next phase of compensation. There were 3 compensation phases, characterized by 3 levels of CF, HR and respiratory wave amplitudes (RESP). Cardiac output (Ca Outp) reflected only two phases. The pig recording of 7/13/06; time window 199.8 min.
Polygraphic traces during hemorrhage. Mean arterial blood pressure was 40 mmHg, maintained by a computer controlled system. In the first phase of hemorrhage carotid flow pulse (Car Fl R), pulse oximeter signal (POX) and skin blood flow (Skin BF- measured by LDF; both sensors were placed on nose). REG showed compensatory amplitude increase. The involvement of various organs is represented by different traces. Traces characterize various phases of hemorrhage compensation. The transient POX amplitude increase ended when heart rate (HR) increase indicated the next phase of compensation. There were 3 compensation phases, characterized by 3 levels of CF, HR and respiratory wave amplitudes (RESP). Cardiac output (Ca Outp) reflected only two phases. The pig recording of 7/13/06; time window 199.8 min.

Summary of CBF AR changes during challenges in PEEP group. CBF AR status was calculated as the relationship to SAP change. (See Table 1 for legend).

CBF ARCFpCFmREG1dCBFLDFICPCVPPAPpO2CO2
Active214222182825221427
Passive831611999121710
A/ P ratio1.750.331.831.750.672.332.081.831.172.25

Summary of CBF AR changes during challenges in hemorrhage group. CBF AR status was calculated as the relationship to SAP change: identical change of modality CBF AR was considered as passive (-); in case of inverted phase, CBF AR was considered as active (+). Artifact contaminated signals, mixed change or lack of signal were excluded from evaluation (0). Legend: SAP: systemic arterial pressure; CFa: carotid flow pulse amplitude; mean: CFm: mean pulse amplitude; REG1d: REG first derivative; CBF: absolute blood flow; LDF: laser Doppler flow; ICP: intracranial pressure; CVP: central venous pressure; PAP: pulmonary arterial pressure; pO2: pulse oximetry pulse amplitude; CO2: exhaled CO2 concentration; +: increase - i.e. identical change; -: decrease - i.e. opposite phase; 0: no data or artifact, no change; Trendelenburg: Trendelenburg position; rTrendelenburg: reverse Trendelenburg position; iso-prop transit: transition of anesthesia from isoflurane to propofol; A/P ratio: ratio of active/passive CBF AR status.

Pig #ChallengeSAPCFaCFmREG1dCBFLDFICPCVPPAPpO2CO2
1hemorrhage-+-0+0---+-
resuscitation++++00+000+
lethal bleeding---+00-----
2hemorrhage-000+-+-0+-
resuscitation+000-++00+-
CO2 inhalation+0000+++0++
lethal bleeding-000+---0--
3CO2 inhalation+-+-+0++0-+
iso-prop transit+-+-+0++0-+
hemorrhage-+-+0-+-0+-
resuscitation++++++++00+
CO2 inhalation+--/+-+0++00+
CO2 inhalation+--/+-++++0-+
4CO2 inhalation0--0+0++0++
hemorrhage-++++0--0+0
5iso-prop transit+-++++++++0
CO2 inhalation+--/+0++0++-+
CO2 inhalation+--/+++++++-+
Trendelenburg-/+0+0--++0+0
rTrendelenburg+++-++--000
hemorrhage--/+-/+0+---0--
6iso-prop transit+-+-/+-/+0-/+-/++00
CO2 inhalation-+-0+0++00+
CO2 inhalation-+-0+0++00+
hemorrhage-+--+0----/+-
CO2 inhalation000++0+++-/++
CO2 inhalation0000+0+000+
CO2 inhalation0++0+0+000+
CO2 inhalation0++0+0+000+
11iso-prop transit+-+-0+/--++--
hemorrhage-+-+0-+0-+-
resuscitation++++0++++-0
14iso-prop transit+-0-++--0--/+
hemorrhage-+-+--+0-+-
CBF AR active1811290940144
CBF AR passive51761116171811617
A/ P ratio3.60.12.00.80.00.50.20.02.30.2
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