Dopamine infused continuously at high concentration with a low flow rate affects arterial blood pressure fluctuation waves

✓ A strategy for intraoperative cerebral protection is described in which intraoperative electroencephalography is used to titrate the level of inspired isoflurane given for anesthesia to obtain isoelectricity prior to temporary vessel occlusion during repair of difficult aneurysms. During temporary vessel occlusion, arterial blood pressure is maintained or increased with an inotropic or vasopressor agent. After clipping of the aneurysm, the concentration of isoflurane is reduced to allow the patient to awaken in the operating room for early postoperative neurological examination. The combination of a high concentration of isoflurane, temporary vessel occlusion, and maintenance of arterial blood pressure may be a useful protective regimen during neurovascular procedures.

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Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1991.261.4.h982 ◽

1991 ◽

Vol 261 (4) ◽

pp. H982-H988

Author(s):

J. H. Sindrup ◽

J. Kastrup ◽

H. Christensen ◽

B. Jorgensen

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Blood Flow ◽

Arterial Blood Pressure ◽

Flow Rate ◽

Mean Arterial Blood Pressure ◽

Blood Flow Rate ◽

Tissue Blood Flow ◽

Peripheral Blood Flow ◽

Arterial Blood

Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease in mean arterial blood pressure (P less than 0.001) were observed. The duration of this hyperemic phase was 116 min. A highly significant reduction of the subcutaneous vascular resistance (50%) was demonstrated during the hyperemic blood flow rate phase compared with the surrounding phases (P less than 0.0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.

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Pressure Fluctuation on Casing Wall of Isolated Axial Compressor Rotors at Low Flow Rate

Journal of Turbomachinery ◽

10.1115/1.2929208 ◽

1993 ◽

Vol 115 (1) ◽

pp. 19-26 ◽

Cited By ~ 3

Author(s):

M. Inoue ◽

M. Kuroumaru ◽

Y. Ando

Keyword(s):

Flow Rate ◽

Pressure Fluctuation ◽

Correlation Functions ◽

Pressure Fluctuations ◽

Axial Compressor ◽

Axial Flow ◽

Tip Clearance ◽

Low Flow ◽

Flow Compressor ◽

Low Flow Rate

The pressure fluctuations on the casing wall of two axial flow compressor rotors with various tip clearances have been analyzed by the use of two kinds of correlation functions. The behavior of the pressure fluctuation varies depending on tip clearance and blade solidity. In the case of small tip clearance, the nature of disturbances becomes random as the flow rate is reduced to a stall condition. For moderate tip clearance, coherent-structured disturbances appear intermittently at low flow rate. They appear more frequently as the solidity is increased and the flow rate becomes lower. For large tip clearance, the coherent structured disturbances exist even at considerably higher flow rates. Corresponding to these features, there are peculiar patterns in the correlation designated as “phase-locked correlation functions.”

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Closure to “Discussion of ‘Pressure Fluctuation on Casing Wall of Isolated Axial Compressor Rotors at Low Flow Rate’” (1993, ASME J. Turbomach., 115, p. 27)

Journal of Turbomachinery ◽

10.1115/1.2929211 ◽

1993 ◽

Vol 115 (1) ◽

pp. 27-27

Author(s):

M. Inoue ◽

M. Kuroumaru ◽

Y. Ando

Keyword(s):

Flow Rate ◽

Pressure Fluctuation ◽

Axial Compressor ◽

Low Flow ◽

Low Flow Rate

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Abstract 2477: Repetitive Apneic Events Augment Arterial Blood Pressure Fluctuation in Patients with Central and Obstructive Sleep Apnea Syndrome

Circulation ◽

10.1161/circ.118.suppl_18.s_733-d ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Takeshi Takamura ◽

Kaoru Dohi ◽

Katsuya Onishi ◽

Emiyo Ogawa ◽

Hiroshi Nakajima ◽

...

Keyword(s):

Blood Pressure ◽

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Obstructive Sleep Apnea Syndrome ◽

Pressure Fluctuation ◽

Sleep Apnea Syndrome ◽

Arterial Blood ◽

Obstructive Sleep ◽

Apnea Syndrome ◽

Blood Pressure Fluctuation

Background: Sleep apnea-hypopneas induce transient increases in arterial blood pressure (BP). We test the hypothesis that periodic nocturnal apneic events augment those hemodynamic responses in patients both with central and obstructive sleep apnea syndrome (SAS). Methods: Eleven patients with central SAS (CSAS: mean age 70 ± 10 years), 11 patients with obstructive SAS (OSAS: mean age 64 ± 12 years), and 8 normal controls (Control) were studied. Polysomnography was performed and BP was measured on a beat-by-beat basis by finger plethysmography all through the sleep. Severity of SAS was assessed by apnea-hypopnea index (AHI). The degree of BP fluctuation associated with periodic nocturnal apnea-hypopnea was assessed by spectral analysis of mean BP variability. Spectral plots of mean BP were calculated in 2-min segments using a maximum entropy method. Power spectrum of mean BP variability was quantified by measuring the area in the very-low-frequency band which coincides with frequency of apnea-hypopneas (sleep apnea band: 0.01– 0.03 Hz), and was normalized by dividing by the total power in the spectrum up to 0.4 Hz. Results: AHI was similar in CSAS and OSAS (38.3 ± 9.5* and 39.8 ± 11.3*, *p<0.05 vs. Control: 2.5±1.6*). Repetitive fluctuations in BP coincided with periodic apnea-hypopneas were clearly observed in patients with SAS, and were more prominent in CSAS (Normalized spectral power of mean BP in sleep apnea band: 0.72 ± 0.10*† in CSAS, 0.62 ±0.13* in OSAS, and 0.46±0.07 in Control, * p<0.05 vs. Control, and †p<0.05 vs. OSAS). Conclusion: Periodic nocturnal apneic events augment blood pressure fluctuation in patients both with central and obstructive SAS.smoking.

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102 Convertion of high-flow rate and low concentration gas to low-flow rate and high concentration gas using nonequilibrium plasma

The Proceedings of Conference of Kansai Branch ◽

10.1299/jsmekansai.2000.75._1-3_ ◽

2000 ◽

Vol 2000.75 (0) ◽

pp. _1-3_-_1-4_

Author(s):

Yoshihiro Yamamoto ◽

Tomoyuki Kuroki ◽

Masaaki Okubo ◽

Toshiaki Yamamoto

Keyword(s):

Flow Rate ◽

Nonequilibrium Plasma ◽

High Flow ◽

High Flow Rate ◽

Low Flow ◽

High Concentration ◽

Low Concentration ◽

Low Flow Rate

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Rotordynamic Forces Acting on a Two-Stage Inducer

Journal of Fluids Engineering ◽

10.1115/1.4037986 ◽

2017 ◽

Vol 140 (2) ◽

Author(s):

Naoki Nagao ◽

Katsuji Nagaura ◽

Tsutomu Tamura ◽

Satoshi Hasegawa ◽

Masaharu Uchiumi

Keyword(s):

Flow Rate ◽

Pressure Fluctuation ◽

Frequency Ratio ◽

Test Stand ◽

Low Flow ◽

Strong Nonlinearity ◽

Two Stage ◽

Second Stage ◽

Rotordynamic Forces ◽

Low Flow Rate

Rocket turbopumps sometimes experience self-excited shaft vibration due to rotordynamic forces. To prevent this vibration, a key step is to establish a method to measure and evaluate the rotordynamic forces that act on turbopump components. In this study, we measured rotordynamic forces acting on a two-stage inducer using a rotordynamic test stand developed in 2012 at Kakuda Space Center. In noncavitating conditions, we did not observe strong nonlinearities in rotordynamic forces in the inducer at low flow rate conditions. The results of the pressure fluctuation on the inducer showed that rotordynamic forces were mainly excited in the second stage of the inducer. In cavitating conditions, we found that there is no strong nonlinearity between cavitating rotordynamic forces and the whirling frequency ratio in the inducer. These results show the robustness of the rotordynamic forces acting on the inducer against the flow rate and cavitation.

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