scholarly journals A Dynamic Model of Rescuer Parameters for Optimizing Blood Gas Delivery during Cardiopulmonary Resuscitation

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Ali Jalali ◽  
Allan F. Simpao ◽  
Jorge A. Gálvez ◽  
Robert A. Berg ◽  
Vinay M. Nadkarni ◽  
...  
Keyword(s):  
Global Optimization ◽  
Cardiopulmonary Resuscitation ◽  
Optimization Technique ◽  
Performance Measure ◽  
Sequential Optimization ◽  
Blood Gas ◽  
Optimization Scheme ◽  
Total Blood ◽  
Active Research

Introduction. The quality of cardiopulmonary resuscitation (CPR) has been shown to impact patient outcomes. However, post-CPR morbidity and mortality remain high, and CPR optimization is an area of active research. One approach to optimizing CPR involves establishing reliable CPR performance measures and then modifying CPR parameters, such as compressions and ventilator breaths, to enhance these measures. We aimed to define a reliable CPR performance measure, optimize the CPR performance based on the defined measure and design a dynamically optimized scheme that varies CPR parameters to optimize CPR performance. Materials and Methods. We selected total blood gas delivery (systemic oxygen delivery and carbon dioxide delivery to the lungs) as an objective function for maximization. CPR parameters were divided into three categories: rescuer dependent, patient dependent, and constant parameters. Two optimization schemes were developed using simulated annealing method: a global optimization scheme and a sequential optimization scheme. Results and Discussion. Variations of CPR parameters over CPR sequences (cycles) were analyzed. Across all patient groups, the sequential optimization scheme resulted in significant enhancement in the effectiveness of the CPR procedure when compared to the global optimization scheme. Conclusions. Our study illustrates the potential benefit of considering dynamic changes in rescuer-dependent parameters during CPR in order to improve performance. The advantage of the sequential optimization technique stemmed from its dynamically adapting effect. Our CPR optimization findings suggest that as CPR progresses, the compression to ventilation ratio should decrease, and the sequential optimization technique can potentially improve CPR performance. Validation in vivo is needed before implementing these changes in actual practice.

Improving Cardiopulmonary Resuscitation (CPR) by Dynamic Variation of CPR Parameters

2013 ◽  
Author(s):  
Ali Jalali ◽  
Robert A. Berg ◽  
Vinay M. Nadkarni ◽  
C. Nataraj
Keyword(s):  
Cardiopulmonary Resuscitation ◽  
Objective Function ◽  
Critical Role ◽  
Optimization Procedure ◽  
Heart Association ◽  
Sequential Optimization ◽  
Implicit Assumption ◽  
Total Blood ◽  
Compression Depth ◽  
Systemic Oxygen

Cardiopulmonary resuscitation (CPR) is a commonly used procedure and plays a critical role in saving the lives of patients suffering from cardiac arrest. This paper is concerned with the design of a dynamic technique to optimize the performance of CPR and to consequently improve its outcome, the survival rate. Current American Heart Association (AHA) guidelines treat CPR as a static procedure with fixed parameters. These guidelines set fixed values for CPR parameters such as compression to ventilation ratio, chest compression depth, etc., with an implicit assumption that they are somehow “optimal,” which has not been really substantiated. In this study, in a quest to improve this oft-used procedure, an interactive technique has been developed for dynamically changing the CPR parameters. Total blood gas delivery which is combination of systemic oxygen delivery and carbon dioxide delivery to the lungs has been defined as the objective function, and a sequential optimization procedure has been explored to optimize the objective function by dynamically adjusting the CPR parameters. The results of comparison between the sequential optimization procedure and the global optimization procedure show that the sequential optimization procedure could significantly enhance the effectiveness of CPR.

scholarly journals Optimization of an Observing System Design for the North Atlantic Meridional Overturning Circulation

2008 ◽  
Vol 25 (4) ◽  
pp. 625-634 ◽  
Author(s):  
Johanna Baehr ◽  
David McInerney ◽  
Klaus Keller ◽  
Jochem Marotzke
Keyword(s):  
Global Optimization ◽  
North Atlantic ◽  
Optimization Technique ◽  
Meridional Overturning Circulation ◽  
Sequential Optimization ◽  
Overturning Circulation ◽  
Array Design ◽  
The North ◽  
Meridional Overturning ◽  
The North Atlantic

Abstract Three methods are analyzed for the design of ocean observing systems to monitor the meridional overturning circulation (MOC) in the North Atlantic. Specifically, a continuous monitoring array to monitor the MOC at 1000 m at different latitudes is “deployed” into a numerical model. The authors compare array design methods guided by (i) physical intuition (heuristic array design), (ii) sequential optimization, and (iii) global optimization. The global optimization technique can recover the true global solution for the analyzed array design, while gradient-based optimization would be prone to misconverge. Both global optimization and heuristic array design yield considerably improved results over sequential array design. Global optimization always outperforms the heuristic array design in terms of minimizing the root-mean-square error. However, whether the results are physically meaningful is not guaranteed; the apparent success might merely represent a solution in which misfits compensate for each other accidentally. Testing the solution gained from global optimization in an independent dataset can provide crucial information about the solution’s robustness.

scholarly journals Formulation and optimization of gastroretentive bilayer tablets of calcium carbonate using D-optimal mixture design

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 057-071
Author(s):  
Manasa Moganti ◽  
Shivakumar H. Nanjappa
Keyword(s):  
Calcium Carbonate ◽  
Optimization Technique ◽  
Lag Time ◽  
Mixture Design ◽  
Burst Release ◽  
Bilayer Tablets ◽  
Absorption Window ◽  
Upper Gastrointestinal ◽  
Gastric Retention Time

Abstract Gastroretentive bilayer tablets of calcium carbonate (CC) were developed using D-optimal mixture design. The effect of formulation factors such as levels of HPMC K100 M (X1), sodium bicarbonate (X2), and HPMC E15 LV (X3) on responses like floating lag time (R1) and release of CC at 1 h (R2) and 6 h (R3) was elucidated. The optimized formulations developed by numerical optimization technique were found to have short floating lag time (2.85 ± 0.98 min), minimum burst release (27.02 ± 1.18%), and controlled yet near complete release (88.98 ± 2.75%) at 6 h. In vivo radiographic studies in rabbits indicated that optimized batch displayed a mean gastric retention time (GRT) of 5.5 ± 1 h which was significantly prolonged (P < 0.05) compared to the conventional tablets that displayed a GRT of less than 1 h. The studies proved that the gastroretentive tablets can be a promising platform to improve bioavailability of nutrients having absorption window in upper gastrointestinal tract.

Cerebral oxygen availability by NIR spectroscopy during transient hypoxia in humans

1990 ◽  
Vol 69 (3) ◽  
pp. 907-913 ◽  
Author(s):  
N. B. Hampson ◽  
E. M. Camporesi ◽  
B. W. Stolp ◽  
R. E. Moon ◽  
J. E. Shook ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Volume ◽  
Near Infrared ◽  
Cerebral Blood Volume ◽  
Minute Ventilation ◽  
Nir Spectroscopy ◽  
Redox Status ◽  
Total Blood ◽  
Arterial Ph

The effects of mild hypoxia on brain oxyhemoglobin, cytochrome a,a3 redox status, and cerebral blood volume were studied using near-infrared spectroscopy in eight healthy volunteers. Incremental hypoxia reaching 70% arterial O2 saturation was produced in normocapnia [end-tidal PCO2 (PETCO2) 36.9 +/- 2.6 to 34.9 +/- 3.4 Torr] or hypocapnia (PETCO2 32.8 +/- 0.6 to 23.7 +/- 0.6 Torr) by an 8-min rebreathing technique and regulation of inspired CO2. Normocapnic hypoxia was characterized by progressive reductions in arterial PO2 (PaO2, 89.1 +/- 3.5 to 34.1 +/- 0.1 Torr) with stable PETCO2, arterial PCO2 (PaCO2), and arterial pH and resulted in increases in heart rate (35%) systolic blood pressure (14%), and minute ventilation (5-fold). Hypocapnic hypoxia resulted in progressively decreasing PaO2 (100.2 +/- 3.6 to 28.9 +/- 0.1 Torr), with progressive reduction in PaCO2 (39.0 +/- 1.6 to 27.3 +/- 1.9 Torr), and an increase in arterial pH (7.41 +/- 0.02 to 7.53 +/- 0.03), heart rate (61%), and ventilation (3-fold). In the brain, hypoxia resulted in a steady decline of cerebral oxyhemoglobin content and a decrease in oxidized cytochrome a,a3. Significantly greater loss of oxidized cytochrome a,a3 occurred for a given decrease in oxyhemoglobin during hypocapnic hypoxia relative to normocapnic hypoxia. Total blood volume response during hypoxia also was significantly attenuated by hypocapnia, because the increase in volume was only half that of normocapnic subjects. We conclude that cytochrome a,a3 oxidation level in vivo decreases at mild levels of hypoxia. PaCO is an important determinant of brain oxygenation, because it modulates ventilatory, cardiovascular, and cerebral O2 delivery responses to hypoxia.

Pulmonary oxygen toxicity in awake dogs: metabolic and physiological effects

1984 ◽  
Vol 57 (5) ◽  
pp. 1480-1488 ◽  
Author(s):  
A. L. Harabin ◽  
L. D. Homer ◽  
M. E. Bradley
Keyword(s):  
Oxygen Toxicity ◽  
Plasma Renin ◽  
Hemodynamic Instability ◽  
Blood Gas ◽  
Metabolic Capacity ◽  
Pulmonary Endothelium ◽  
Physiological Variables ◽  
Terminal Response ◽  
Ace Activity

Because the pulmonary endothelium is sensitive to O2-induced damage, we studied in vivo angiotensin-converting enzyme (ACE) activity in the lungs of 14 catheterized unanesthetized dogs exposed either to air or continuous 100% O2 at 1 ATA. For 5 days, or until the dog died, we measured physiological variables and lung ACE activity. The metabolic data were analyzed with a model that accounted for the effect of changes in cardiac output. Nine dogs breathing O2 lived 88 +/- 21.8 (SD) h and except for blood O2 tensions were indistinguishible from controls until development of a terminal response lasting only a few hours. Hemodynamic instability preceded a precipitous terminal change in blood gas tensions which resulted in impairment of arterial oxygenation, hypercapnia, and acidosis. Plasma renin activity increased. The metabolic capacity of the pulmonary endothelium of O2-exposed animals decreased with time so that after 96 h it was 50% of the control. That of five control animals did not change with time. Thus changes in lung ACE activity preceded alterations in hemodynamics or gas exchange, and the contributions of each are discussed.

scholarly journals Oxygen and Carbon Dioxide Transport Characteristics of the Blood of the Nile Monitor Lizard (Varanus Niloticus)

1987 ◽  
Vol 130 (1) ◽  
pp. 27-38
Author(s):  
JAMES W. HICKS ◽  
ATSUSHI ISHIMATSU ◽  
NORBERT HEISLER
Keyword(s):  
Carbon Dioxide ◽  
Haemoglobin Concentration ◽  
Oxygen Affinity ◽  
Total Blood ◽  
Carbon Dioxide Transport ◽  
Monitor Lizard ◽  
The Right ◽  
Dissociation Curves

Oxygen and carbon dioxide dissociation curves were constructed for the blood of the Nile monitor lizard, Varanus niloticus, acclimated for 12h at 25 and 35°C. The oxygen affinity of Varanus blood was low when Pco2 w a s in the range of in vivo values (25°C: P50 = 34.3 at PCOCO2 = 21 mmHg; 35°C: P50 = 46.2 mmHg at PCOCO2 = 35 mmHg; 1 mmHg = 133.3 Pa), and the oxygen dissociation curves were highly sigmoidal (Hill's n = 2.97 at 25°C and 3.40 at 35°C). The position of the O2 curves was relatively insensitive to temperature change with an apparent enthalpy of oxygenation (ΔH) of −9.2kJ mol−1. The carbon dioxide dissociation curves were shifted to the right with increasing temperature by decreasing total CCOCO2 at fixed PCOCO2, whereas the state of oxygenation had little effect on total blood CO2 content. The in vitro buffer value of true plasma (Δ[HCO3−]pl/-ΔpHpl) rose from 12.0 mequiv pH−1−1 at 25°C to 17.5 mequiv pH−11−1 at 35°C, reflecting a reversible increase of about 30% in haemoglobin concentration and haematocrit levels during resting conditions in vivo.

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