Mechanisms of blood flow during pneumatic vest cardiopulmonary resuscitation

Mechanisms of blood flow during cardiopulmonary resuscitation (CPR) were studied in a canine model with implanted mitral and aortic flow probes and by use of cineangiography. Intrathoracic pressure (ITP) fluctuations were induced by a circumferential pneumatic vest, with and without simultaneous ventilation, and by use of positive-pressure ventilation alone. Vascular volume and compression rate were altered with each CPR mode. Antegrade mitral flow was interpreted as left ventricular (LV) inflow, and antegrade aortic flow was interpreted as LV outflow. The pneumatic vest was expected to elevate ITP uniformly and thus produce simultaneous LV inflow and LV outflow throughout compression. This pattern, the passive conduit of "thoracic pump" physiology, was unequivocally demonstrated only during ITP elevation with positive-pressure ventilation alone at slow rates. During vest CPR, LV outflow started promptly with the onset of compression, whereas LV inflow was delayed. At compression rates of 50 times/min and normal vascular filling pressures, the delay was sufficiently long that all LV filling occurred with release of compression. This is the pattern that would be expected with direct LV compression or "cardiac pump" physiology. During the early part of the compression phase, catheter tip transducer LV and left atrial pressure measurements demonstrated gradients necessitating mitral valve closure, while cineangiography showed dye droplets moving from the large pulmonary veins retrograde to the small pulmonary veins. When the compression rate was reduced and/or when intravascular pressures were raised with volume infusion, LV inflow was observed at some point during the compressive phase. Thus, under these conditions, features of both thoracic pump and cardiac pump physiology occurred within the same compression. Our findings are not explained by the conventional conceptions of either thoracic pump or cardiac compression CPR mechanisms alone.

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Heart-lung interactions during positive pressure ventilation: left ventricular pressure-volume momentary response to airway pressure elevation

Acta Anaesthesiologica Scandinavica ◽

10.1034/j.1399-6576.2001.045006702.x ◽

2001 ◽

Vol 45 (6) ◽

pp. 702-709 ◽

Cited By ~ 11

Author(s):

M. F. Haney ◽

G. Johansson ◽

S. Häggmark ◽

B. Biber

Keyword(s):

Airway Pressure ◽

Positive Pressure Ventilation ◽

Left Ventricular Pressure ◽

Left Ventricular ◽

Ventricular Pressure ◽

Positive Pressure ◽

Pressure Elevation

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Pattern of blood flow in the pulmonary veins of the dog

Journal of Applied Physiology ◽

10.1152/jappl.1965.20.6.1118 ◽

1965 ◽

Vol 20 (6) ◽

pp. 1118-1128 ◽

Cited By ~ 67

Author(s):

Eugene Morkin ◽

John A. Collins ◽

Harold S. Goldman ◽

Alfred P. Fishman

Keyword(s):

Blood Flow ◽

Pulmonary Circulation ◽

Pulmonary Veins ◽

Electromagnetic Flowmeter ◽

Sine Wave ◽

Left Ventricular ◽

Mean Flow ◽

Venous Flow ◽

Pulmonary Venous Flow ◽

Atrial Contraction

The pattern of blood flow in the large pulmonary veins was studied in dogs by chronic implantation of sine-wave electromagnetic flowmeters and cineangiographic observations. These revealed that: 1) pulmonary venous flow is continuous and pulsatile with peak rate of flow of approximately twice the mean flow; 2) the initial rapid increase in venous flow occurs 0.10 sec after the onset of ventricular systole, reaching a peak at the time of closure of the A-V valves; 3) left atrial contraction produces a fleeting slowing or reversal of flow; and 4) respiratory variations in pulmonary venous flow follow those in pulmonary arterial flow, beat by beat. The genesis of phasic pulmonary venous flow was investigated by analysis of pressure and flow curves from the two sides of the heart, by consideration of the energy required for left ventricular filling, and by reconstruction of the pulmonary venous flow pulse using a mathematical model of the pulmonary circulation. These three lines of evidence are consistent in indicating that the transmitted right ventricular pressure is the major determinant of the pulmonary venous flow pattern in the dog. pulsatile pulmonary venous flow; pulmonary venous flow; pulmonary circulation; ventricular suction; respiration on pulmonary circulation; pulmonary venous angiography; pulmonary veno-atrial junctions; electromagnetic flowmeter; cineangiography Submitted on November 16, 1964

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Abstract 59: The Incidence Of Pulmonary Aspiration With Laryngeal Mask Airway Use During Cardiopulmonary Resuscitation And Positive Pressure Ventilation In Swine.

Circulation ◽

10.1161/circ.116.suppl_16.ii_935-c ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Brian Suffoletto ◽

James Menegazzi ◽

Eric Logue ◽

David Salcido

Keyword(s):

Laryngeal Mask Airway ◽

Cardiopulmonary Resuscitation ◽

Positive Pressure Ventilation ◽

Validation Cohort ◽

Pulmonary Aspiration ◽

Laryngeal Mask ◽

Positive Pressure ◽

Suction Catheter ◽

Chest Compressions ◽

Lung Expansion

Objective: Pulmonary aspiration of gastric contents occurs 20 –30% of the time during cardiopulmonary resuscitation (CPR) of cardiac arrest. This is due to loss of protective airway reflexes, pressure changes generated during CPR, and positive pressure ventilation (PPV). Even though the American Heart Association (AHA) has recommended the laryngeal mask airway (LMA) as an acceptable alternative airway for use by EMS personnel, concerns over the capacity of the device to protect from pulmonary aspiration remain. We sought to determine the incidence of aspiration after LMA placement, CPR and PPV. Methods: We conducted a prospective study on 16 consecutive post-experimental mixed-breed domestic swine of either sex (mean mass 25.7 ±1.4 kgs). A standard size-4 LMA was modified so that a vacuum catheter could be advanced into and past the LMA diaphragm. The LMA was placed into the hypopharynx and its position confirmed using End-tidal CO 2 and direct visualization of lung expansion. Fifteen milliliters of heparinized blood were instilled into the pharynx. After 5 PPVs with a mechanical ventilator, chest compressions were performed for 60s with asynchronous ventilations continuing at a rate of 12 per minute. After chest compressions, a suction catheter was inserted through the cuff and suction applied for approximately 1 minute. The catheter was removed and inspected for signs of blood. The LMA cuff was deflated and the LMA removed. The intima of the LMA diaphragm was inspected for signs of blood. In a validation cohort of 4 animals, the LMA was reinserted, a cricothyrotomy performed and 5 mL of blood instilled directly into the trachea. Results: There were 0/16 (95% CI=0 –17%) with a positive tests for the presence of blood in both the vacuum catheter and the intima of the LMA diaphragm. In the validation cohort, all four were positive for blood in both the vacuum catheter and the intima of the LMA diaphragm. Conclusions: In this simple model of regurgitation of after LMA placement, there was no sign of pulmonary aspiration, and no evidence that blood had passed beyond the seal created by the LMA cuff. Concerns over aspiration with LMA use may be unfounded. Future studies should determine the frequency of pulmonary aspiration after LMA placement in the clinical setting.

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Continuous Airway Pressure Breathing With the Head-Box in the Newborn Lamb: Effects on Regional Blood Flows

PEDIATRICS ◽

10.1542/peds.59.6.858 ◽

1977 ◽

Vol 59 (6) ◽

pp. 858-864

Author(s):

G. Gabriele ◽

C. R. Rosenfeld ◽

D. E. Fixler ◽

J. M. Wheeler

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Airway Pressure ◽

Left Ventricular Pressure ◽

Blood Gases ◽

Ocular Blood Flow ◽

Left Ventricular ◽

Positive Pressure ◽

Blood Flows ◽

Arterial Blood

Continuous airway pressure delivered by a head-box is an accepted means of treating clinical hyaline membrane disease. To investigate hemodynamic alterations resulting from its use, eight newborn lambs, 1 to 6 days of age, were studied at 6 and 11 mm Hg of positive pressure, while spontaneously breathing room air. Organ blood flows and cardiac output were measured with 25 µ-diameter radioactive microspheres. Heart rate, left ventricular pressure, and arterial blood gases did not change during the study. Jugular venous pressures increased from 6.4 mm Hg to 18.6 and 24.2 mm Hg at 6 and 11 mm Hg, respectively (P < .005). Cardiac output decreased approximately 20% at either intrachamber pressure setting. Renal blood flow fell 21% at 11 mm Hg. No significant changes in blood flow were found in the brain, gastrointestinal tract, spleen, heart, or liver when compared to control flows. Of particular interest was the finding of a 28% reduction in ocular blood flow at 6 mm Hg and 52% at 11 mm Hg. From these results, we conclude that substantial cardiovascular alterations may occur during the application of head-box continuous airway pressure breathing, including a significant reduction in ocular blood flow.

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Left ventricular dysfunction in Duchenne muscular dystrophy

Cardiology in the Young ◽

10.1017/s1047951119002610 ◽

2020 ◽

Vol 30 (2) ◽

pp. 171-176

Author(s):

Katherine A. James ◽

Jane Gralla ◽

Leslie A. Ridall ◽

ThuyQuynh N. Do ◽

Angela S. Czaja ◽

...

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Ejection Fraction ◽

Left Ventricular Dysfunction ◽

Positive Pressure Ventilation ◽

Ventricular Dysfunction ◽

Left Ventricular ◽

Positive Pressure ◽

Left Ventricle Function ◽

Non Invasive

AbstractBackground:Duchenne muscular dystrophy is associated with progressive cardiorespiratory failure, including left ventricular dysfunction.Methods and Results:Males with probable or definite diagnosis of Duchenne muscular dystrophy, diagnosed between 1 January, 1982 and 31 December, 2011, were identified from the Muscular Dystrophy Surveillance Tracking and Research Network database. Two non-mutually exclusive groups were created: patients with ≥2 echocardiograms and non-invasive positive pressure ventilation-compliant patients with ≥1 recorded ejection fraction. Quantitative left ventricular dysfunction was defined as an ejection fraction <55%. Qualitative dysfunction was defined as mild, moderate, or severe. Progression of quantitative left ventricular dysfunction was modelled as a continuous time-varying outcome. Change in qualitative left ventricle function was assessed by the percentage of patients within each category at each age. Forty-one percent (n = 403) had ≥2 ejection fractions containing 998 qualitative assessments with a mean age at first echo of 10.8 ± 4.6 years, with an average first ejection fraction of 63.1 ± 12.6%. Mean age at first echo with an ejection fraction <55 was 15.2 ± 3.9 years. Thirty-five percent (140/403) were non-invasive positive pressure ventilation-compliant and had ejection fraction information. The estimated rate of decline in ejection fraction from first ejection fraction was 1.6% per year and initiation of non-invasive positive pressure ventilation did not change this rate.Conclusions:In our cohort, we observed that left ventricle function in patients with Duchenne muscular dystrophy declined over time, independent of non-invasive positive pressure ventilation use. Future studies are needed to examine the impact of respiratory support on cardiac function.

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The Effect of a Modified Constant Flow Insufflation of Oxygen during Cardiopulmonary Resuscitation in a Rat Model of Respiratory Cardiac Arrest on Arterial Oxygenation, Alveolar Barotrauma, and Brain Tissue Injury

Emergency Medicine International ◽

10.1155/2020/8913571 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

Yoonje Lee ◽

Sang-hyun Lee ◽

Hyuk Joong Choi ◽

Jinkyu Park ◽

Sejin Hwang ◽

...

Keyword(s):

Cardiac Arrest ◽

Cardiopulmonary Resuscitation ◽

Rat Model ◽

Continuous Flow ◽

Positive Pressure Ventilation ◽

Respiratory Arrest ◽

Intermittent Positive Pressure Ventilation ◽

Positive Pressure ◽

Alveolar Wall ◽

Arterial Blood

Aim. Intermittent positive pressure ventilation (IPPV) can adversely affect cardiopulmonary resuscitation outcomes by increasing the intrathoracic pressure. Continuous flow insufflation of oxygen (CFIO) has been investigated as a potential alternative, but evidence supporting its superiority over intermittent positive pressure ventilation in cases of cardiac arrest is scant. The aim of the current study was to compare the effects of continuous flow insufflation of oxygen using a one-way valve during cardiopulmonary-resuscitation with intermittent positive pressure ventilation in a rat model of respiratory arrest. Methods. Male Sprague-Dawley rats weighing 400∼450 g (from minimum to maximum) were randomly assigned to either a sham, IPPV, or CFIO group (n = 10 per group). Respiratory arrest was induced by blocking the endotracheal tube. Arterial blood gas analysis was performed during cardiopulmonary resuscitation to compare the oxygenation levels. Tissues were then harvested to compare the degrees of pulmonary barotrauma and ischemic brain injury. Results. Return of spontaneous circulation was observed in 6/10 rats in the IPPV group and 5/10 in the CFIO group. During cardiopulmonary resuscitation, the mean PaO2 was significantly higher in the CFIO group (83.10 mmHg) than in the IPPV group (56.10 mmHg). Lung biopsy revealed more inflammatory cells and marked thickening of the alveolar wall in the IPPV group; the group also exhibited a higher frequency of neuroglial cells and apoptotic bodies of pyramidal cells, resulting from ischemic injury. Conclusion. In a rat model of respiratory arrest, CFIO using a one-way valve resulted in a greater level of oxygenation and less lung and brain injuries than with IPPV.

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Continuous positive-pressure ventilation does not alter ventricular pressure-volume relationship

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1981.240.6.h821 ◽

1981 ◽

Vol 240 (6) ◽

pp. H821-H826 ◽

Cited By ~ 3

Author(s):

J. E. Fewell ◽

D. R. Abendschein ◽

C. J. Carlson ◽

E. Rapaport ◽

J. F. Murray

Keyword(s):

Mechanical Properties ◽

Positive Pressure Ventilation ◽

Venous Return ◽

Intermittent Positive Pressure Ventilation ◽

Left Ventricular ◽

Positive Pressure ◽

Volume Relationship ◽

Pressure Volume Relationship ◽

The Right ◽

Continuous Positive Pressure

To determine whether alterations in the mechanical properties (i.e., stiffening) of the right and left ventricles contribute to the decrease in right and left ventricular end-diastolic volumes during continuous positive-pressure ventilation (CPPV), we studied six dogs anesthetized with chloralose urethane and ventilated with a volume ventilator. We varied ventricular volumes by withdrawing or infusing blood. Pressure-volume curves, constructed by plotting transmural ventricular end-diastolic pressures against ventricular end-diastolic volumes, did not change during CPPV (12 cmH2O positive end-expiratory pressure) compared to intermittent positive-pressure ventilation (IPPV, 0 cmH2O end-expiratory pressure). We conclude that decreased ventricular end-diastolic volumes during CPPV result primarily from a decrease in venous return. Alterations in the mechanical properties of the ventricles do not play a significant role in this response.

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Descending aortic flow reversal in obstructed total anomalous pulmonary venous connection

Cardiology in the Young ◽

10.1017/s1047951116000214 ◽

2016 ◽

Vol 26 (5) ◽

pp. 1002-1004

Author(s):

Anupama K. Nair ◽

Sitaraman Radhakrishnan ◽

Krishna S. Iyer

Keyword(s):

Ductus Arteriosus ◽

Pulmonary Veins ◽

Left Ventricular ◽

Flow Reversal ◽

Aortic Flow ◽

Severe Pulmonary Hypertension ◽

Descending Thoracic Aorta ◽

Descending Aorta ◽

Left Ventricular Output ◽

Anomalous Pulmonary Venous Connection

AbstractIn this study, we present the case of a neonate with obstructed infracardiac total anomalous pulmonary venous connection with severe pulmonary hypertension and a patent ductus arteriosus with right-to-left shunting. The patient had an unusual finding of pandiastolic flow reversal in the upper descending thoracic aorta. He underwent emergency surgical re-routing of the pulmonary veins to the left atrium, and postoperative echocardiography showed disappearance of the descending aortic flow reversal. We hypothesise that in severely obstructed total anomalous pulmonary venous connection the left ventricular output may be extremely low, resulting in flow reversal in the descending aorta.

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