Mixed Venous Oxygen Saturation as a Promising Parameter for Physiologic Control of Total Artificial Heart

Nakamura, Makoto; Homma, Akihiko; Tatsumi, Eisuke; Uesho, K.; Taenaka, Yoshiyuki; Masuzawa, Toru; Nakamura, Tomomichi; Zhang, Bin; Kakuta, Yukihide; Imada, K.; Nakatani, Takeshi; Takano, Hisateru

doi:10.1097/00002480-200011000-00020

Cited by 9 publications

(7 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Continuous monitoring of SvO 2 using a fiber-optic sensor placed at the tip of a pulmonary catheter has acceptable accuracy (bias <1%) when properly calibrated and recalibrated using a co-oximeter [ 35 ]. The precision is necessarily lower (2SD/mean >5%) [ 10 , 11 ], but is compensated by a very fast response (almost instantaneous) [ 36 ], allowing averaging of several elementary measurements (N) in a few milliseconds and decreasing the standard error of the mean (2SD/√N). Averaging 10 elementary measurements when continuously monitoring SvO 2 allows the same least significant changes to be achieved as when analyzing a unique mixed venous blood sample.…”

Section: Metrological Considerationsmentioning

confidence: 99%

Central venous oxygenation: when physiology explains apparent discrepancies

Squara

2014

Crit Care

View full text Add to dashboard Cite

Central venous oxygen saturation (ScvO2) >70% or mixed venous oxygen saturation (SvO2) >65% is recommended for both septic and non-septic patients. Although it is the task of experts to suggest clear and simple guidelines, there is a risk of reducing critical care to these simple recommendations. This article reviews the basic physiological and pathological features as well as the metrological issues that provide clear evidence that SvO2 and ScvO2 are adaptative variables with large inter-patient variability. This variability is exemplified in a modeled population of 1,000 standard ICU patients and in a real population of 100 patients including 15,860 measurements. In these populations, it can be seen how optimizing one to three of the four S(c)vO2 components homogenized the patients and yields a clear dependency with the fourth one. This explains the discordant results observed in large studies where cardiac output was increased up to predetermined S(c)vO2 thresholds following arterial oxygen hemoglobin saturation, total body oxygen consumption needs and hemoglobin optimization. Although a systematic S(c)vO2 goal-oriented protocol can be statistically profitable before ICU admission, appropriate intensive care mandates determination of the best compromise between S(c)vO2 and its four components, taking into account the specific constraints of each individual patient.

show abstract

Section: Metrological Considerationsmentioning

confidence: 99%

Central venous oxygenation: when physiology explains apparent discrepancies

Squara

2014

Crit Care

View full text Add to dashboard Cite

show abstract

“…An excellent indication of tissue perfusion is given by blood oxygen saturation. [5][6][7][8][9] Unfortunately, the response time of blood oxygen saturation to the physiologic demand is relatively slow, and implantable oxygen saturation sensors capable of long-term, reliable operation are yet to be developed. It was found that P wave activity decayed over time 10 once the natural heart was removed.…”

mentioning

confidence: 99%

Physiologic Control of Rotary Blood Pumps: An In Vitro Study

et al. 2004

View full text Add to dashboard Cite

Rotary blood pumps (RBPs) are currently being used as a bridge to transplantation as well as for myocardial recovery and destination therapy for patients with heart failure. Physiologic control systems for RBPs that can automatically and autonomously adjust the pump flow to match the physiologic requirement of the patient are needed to reduce human intervention and error, while improving the quality of life. Physiologic control systems for RBPs should ensure adequate perfusion while avoiding inflow occlusion via left ventricular (LV) suction for varying clinical and physical activity conditions. For RBPs used as left ventricular assist devices (LVADs), we hypothesize that maintaining a constant average pressure difference between the pulmonary vein and the aorta (deltaPa) would give rise to a physiologically adequate perfusion while avoiding LV suction. Using a mock circulatory system, we tested the performance of the control strategy of maintaining a constant average deltaPa and compared it with the results obtained when a constant average pump pressure head (deltaP) and constant rpm are maintained. The comparison was made for normal, failing, and asystolic left heart during rest and at light exercise. The deltaPa was maintained at 95 +/- 1 mm Hg for all the scenarios. The results indicate that the deltaPa control strategy maintained or restored the total flow rate to that of the physiologically normal heart during rest (3.8 L/m) and light exercise (5.4 L/m) conditions. The deltaPa approach adapted to changing exercise and clinical conditions better than the constant rpm and constant deltaP control strategies. The deltaPa control strategy requires the implantation of two pressure sensors, which may not be clinically feasible. Sensorless RBP control using the deltaPa algorithm, which can eliminate the failure prone pressure sensors, is being currently investigated.

show abstract

“…However, AP is not a direct indicator of physiological demand, and is influenced by many irrelevant factors. An excellent indication of tissue perfusion is given by blood oxygen saturation (4–8). Unfortunately, the response time of blood oxygen saturation to the physiological demand is relatively slow, and implantable oxygen saturation sensors capable of long‐term, reliable operation are yet to be developed.…”

mentioning

confidence: 99%

Control Strategy for Maintaining Physiological Perfusion with Rotary Blood Pumps

Giridharan

Skliar

2003

Artificial Organs

View full text Add to dashboard Cite

We present arguments and simulation results in favor of a novel strategy for control of rotary blood pumps. We suggest that physiological perfusion is achieved when the blood pump is controlled to maintain an average reference differential pressure. In the case of rotary left ventricular assist devices, our simulations show that maintaining a constant average pressure difference between the left ventricle and aorta results in physiological perfusion over a wide range of physical activities and clinical cardiac conditions. We simulated rest, light, and strenuous exercise conditions, corresponding to cardiac demands of 4.92, 7.98, and 14.62 L/min, respectively. For different exercise levels, the clinical conditions ranged from normal to failing to asystolic heart. By maintaining a constant pressure difference of 75 mm Hg between the left ventricle and aorta, with either an axial or a centrifugal blood pump, a total cardiac output close to the physiological cardiac demand was achieved, irrespective of the heart condition. The simulations of the transitions between different levels of exercise indicate that with the same reference differential pressure, the proposed approach leads to rapid adaptation of the total cardiac output to physiological levels, while avoiding suction. Comparison with the traditional control strategy of maintaining a reference rotational speed (rpm) of the pump indicates that though the traditional approach has some degree of adaptability, it is only adequate over a narrow range of cardiac demand and clinical conditions of the patient. Our results indicate that the proposed approach is superior to the alternatives in providing an adequate and autonomous adaptation of the total cardiac output over a broad range of exercise conditions (expected when an assist device is used as a destination therapy) and clinical statuses of the native heart (such as further deterioration or recovery of cardiac function), while having the potential to improve the quality of life of patients by reducing the need for monitoring and frequent human intervention. The proposed approach can be clinically implemented using simple controllers, and requires the implantation of two pressure sensors, or estimation of the pressure difference based on other available measurements.

show abstract

Mixed Venous Oxygen Saturation as a Promising Parameter for Physiologic Control of Total Artificial Heart

Cited by 9 publications

References 11 publications

Central venous oxygenation: when physiology explains apparent discrepancies

Central venous oxygenation: when physiology explains apparent discrepancies

Physiologic Control of Rotary Blood Pumps: An In Vitro Study

Control Strategy for Maintaining Physiological Perfusion with Rotary Blood Pumps

Contact Info

Product

Resources

About