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Biomedical subjects

J M Criley

Publications and source records attributed to J M Criley.

At least 37 records · Page 2Linked to original sources
PubMed1986

Modifications of cardiopulmonary resuscitation based on the cough.

The ability of cardiopulmonary resuscitation (CPR) to provide adequate vital organ blood flow during prolonged resuscitation has long been questioned, as has the mechanism of blood flow during CPR. Because coughing during cardiac arrest has been shown to produce adequate anterograde flow to maintain consciousness in man without compressing the heart, cough CPR has been used as a model of a pure "thoracic pump" mechanism on which to base modifications of CPR. In the thoracic pump mechanism, the left heart is a passive conduit for blood expressed from the pulmonary vasculature to the aorta, and there is selective flow to the brachiocephalic vascular bed because of its low pressure veins, which are protected by closure of thoracic inlet venous valves. Right heart flow from systemic veins to the lungs occurs between applications of pressure. Four alternative modalities exploiting the thoracic pump concept were studied in dogs during ventricular fibrillation with angiographic and pressure recordings: cough CPR, simultaneous chest compression and lung inflation, abdominal compression with lung inflation, and inflation of a vest and binder. The latter technique was associated with successful defibrillation and recovery after more than 30 min of circulatory support during ventricular fibrillation. Preliminary studies in a primate preparation indicate that this technique might be useful for prolonged circulatory support in man when defibrillation is not initially available or successful.

Animals↗
PubMed1985

Mechanical "cough" cardiopulmonary resuscitation during cardiac arrest in dogs.

Hemodynamic findings during ventricular fibrillation (VF) and closed-chest cardiopulmonary resuscitation (CPR) are similar to those described during VF and vigorous coughing. Interventions during CPR that mimic the physiologic events of coughing (high intrathoracic pressure and high intraabdominal pressure) improve perfusion during VF and CPR. An external circulatory assist apparatus was devised to emulate cough physiology, i.e., simultaneous pulsatile increases in intrathoracic pressure (pneumatic vest), intraabdominal pressure (abdominal binder) and airway pressure (high-pressure airway inflation). In this study, vest/binder CPR was compared with conventional CPR during 30 minutes of VF and artificial support in 18 randomized dogs. Defibrillation and long-term (more than 24 hours) survival were chosen as end points. During VF and artificial support, aortic and right atrial (RA) pressures, the instantaneous aortic-RA pressure difference (coronary perfusion pressure) and blood gas levels were measured. After 30 minutes of VF and administration of 1 mg of epinephrine, countershock was attempted. Systolic aortic and RA pressures, mean aortic-RA pressure difference and blood gas levels were not significantly different between dogs that were successfully resuscitated and those that were not. However, peak diastolic coronary perfusion pressure (peak diastolic aortic-RA pressure) for survivors averaged 23 +/- 6 mm Hg, but only 6 +/- 10 mm Hg for nonsurvivors (p less than 0.001). A peak diastolic coronary perfusion pressure 16 mm Hg or greater had a positive and negative predictive value for a successful outcome of 1.00. Only 1 of 9 conventional CPR dogs survived 24 hours; 7 of 9 dogs supported with the vest/binder device were alive and neurologically normal at 24 hours (p = 0.007).(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1985

Predictive indices of successful cardiac resuscitation after prolonged arrest and experimental cardiopulmonary resuscitation.

To determine if clinically accessible hemodynamic and blood gas measurements are of value in predicting outcome of countershock after prolonged ventricular fibrillation (VF) and artificial cardiopulmonary support, 14 dogs were studied during 30 minutes of VF using two randomly assigned closed-chest techniques. Seven dogs underwent conventional CPR; the other seven were supported with a pneumatic thoracic vest and abdominal binder, which were inflated synchronously with the airway. Ascending aortic (Ao), right atrial (RA), and instantaneous coronary perfusion pressures (Ao - RA) were measured at five-minute intervals. Ao and RA blood samples were analyzed at 10, 20, 25 and 30 minutes for PO2, PCO2, and pH. After 25 minutes, 1 mg epinephrine was given intravenously, and five minutes later defibrillation was attempted. If unsuccessful, repeated countershocks, conventional pharmacologic therapy, and artificial support were continued. If a perfusing spontaneous cardiac rhythm did not result within an additional 30 minutes, the experiment was terminated. Six animals developed a perfusing cardiac rhythm after one or more countershocks (Group 1); eight failed to develop a perfusing rhythm after repeated countershocks and an additional 30 minutes of resuscitative effort (Group 2). Five Group 1 dogs received vest/binder artificial support. When measured values were averaged over the study period, Group 1 was found to have a significantly greater Ao end-diastolic pressure (AoEDP) and peak diastolic coronary perfusion pressure (CPP) when compared to Group 2 (23 +/- 6 vs 14 +/- 8 mm Hg, P less than .05; and 22 +/- 6 vs 5 +/- 10 mm Hg, P less than .01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Comparison of ventricular emptying with and without a pressure gradient in patients with hypertrophic cardiomyopathy.

Thirty three patients with hypertrophic cardiomyopathy were studied to determine whether the presence of an intraventricular pressure gradient impaired left ventricular emptying. Patients with resting gradients had a higher mean left ventricular ejection fraction (92 (6.4)%) than patients without a resting or inducible pressure gradient (75.5 (9)%). The rate and degree of emptying increased when gradients greater than 85 mm Hg were induced in two patients with insignificant mitral regurgitation. If the induced gradients had been the result of obstruction a decrease in the rate or degree of ventricular emptying would be expected. Higher ejection fractions in patients with intracavitary pressure gradients as well as enhanced rate and degree of left ventricular emptying with induced gradients are inconsistent with outflow obstruction. These findings support the concept that cavity obliteration is responsible for the pressure gradient in these patients with hypertrophic cardiomyopathy.

Blood Pressure↗
PubMed1985

Has 'obstruction' hindered our understanding of hypertrophic cardiomyopathy?

HCM is a disorder associated with significant morbidity and mortality and a propensity to cause sudden, often unexpected death. The similarity to the symptom complex of aortic stenosis and the presence of a pressure gradient justified the initial assumption that obstruction was of prime importance in HCM and that relief of obstruction was the focal point of rational therapy. However, it is our belief that the dogma of obstruction has impeded progress in and obscured the understanding of HCM and interpretation of its manifestations. The purpose of this article is to call attention to significant discrepancies in the obstructive concept that have been reinforced as new techniques emerged that have allowed further study of the disease. Since neither the presence of a gradient nor SAM can be justifiably equated with the presence of an obstruction, it is proposed that the appellation "obstruction" be reserved for those cases in which the rate of outflow or the rate or degree of ventricular emptying are demonstrably impeded, as in aortic stenosis. Therapy with beta-adrenergic-receptor and calcium channel-blocking agents have shown promise for alleviating symptoms and possibly prolonging life without systematically or predictably affecting the pressure gradient, probably because of their beneficial effects on ventricular relaxation and diastolic filling. Antiarrhythmic therapy has been effective in reducing mortality. Ideally, prevention or regression of the pathologic hypertrophy should be the major focus of future therapeutic interventions in hypertrophic cardiomyopathy.

Blood Pressure↗
PubMed1984

Simultaneous maximal exercise radionuclide angiography and thallium stress perfusion imaging.

Gold-195m is a new ultra-short-lived radionuclide that can be used for cardiac studies. Accurate, reproducible ejection fraction and ventricular wall motion studies can be obtained from first-transit angiography using commercially available imaging and image-processing equipment. The short half-life of gold-195m (30.5 seconds) makes simultaneous dual isotope imaging possible and substantially reduces the radiation exposure from the isotope angiography. The feasibility and possible benefits of performing dual radionuclide studies were evaluated during a single exercise stress test in 24 subjects with known coronary artery disease (CAD) and in 20 normal volunteers. High-quality first-transit angiograms were obtained in all subjects. An 83% sensitivity and 95% specificity for detecting CAD with thallium-201 imaging was noted in this investigation, suggesting that its diagnostic accuracy was not altered by simultaneous dual isotone imaging. When segmental left ventricular (LV) wall motion was compared with thallium-201 perfusion imaging, divergent results were noted in 15 of 44 subjects. An analysis of the ejection fraction (EF) results at rest and stress provided additional information that could be useful in assessing the clinical significance of such differences in segmental wall motion and perfusion. Simultaneous dual isotope imaging appears to be appropriate for situations in which both LV perfusion and function require evaluation. The use of gold-195m allows such information to be obtained from a single exercise test and can thereby reduce the cost and time required for noninvasive evaluations of patients for CAD.

Adult↗
PubMed1984

Hemodynamic effects of continuous abdominal binding during cardiac arrest and resuscitation.

Abdominal binding improves arterial pressure and flow during cardiopulmonary resuscitation (CPR). This study was undertaken to assess the mechanisms of improved hemodynamics during cardiac arrest and CPR with continuous abdominal binding in a canine model (n = 8). Carotid and inferior vena caval (IVC) flow probes and cineangiography were used to observe magnitude and direction of blood flow. CPR with binding significantly increased (p less than 0.001) systolic aortic (Ao) (49 +/- 11 vs 34 +/- 12 mm Hg), right atrial (RA) (49 +/- 11 vs 31 +/- 10 mm Hg) and IVC pressure (50 +/- 7 versus 31 +/- 11 mm Hg) and common carotid flow (1.1 +/- 0.4 vs 0.7 +/- 0.4 ml/min/kg, p less than 0.05) compared with CPR without binding. Aortic, RA and IVC diastolic pressures increased similarly. Binding decreased the diastolic Ao-IVC pressure difference by 8 +/- 12 mm Hg and decreased net IVC flow (0.5 +/- 1.4 vs 1.4 +/- 1.2 ml/min/kg, p less than 0.05). Binding also decreased coronary perfusion pressure (Ao-RA) in 5 of 8 dogs. Cineangiograms showed tricuspid incompetence and reflux from the right atrium to the inferior vena cava during chest compression and IVC-to-right heart inflow during relaxation, which was confirmed by the flowmeter data. Abdominal binding during CPR decreased the size of the perfused vascular bed by inhibiting subdiaphragmatic flow and increased intrathoracic pressure for a given chest compression force, leading to preferential cephalad flow. However, coronary perfusion pressure was often adversely affected. Further studies should be undertaken before the widespread clinical application of continuous abdominal binding during CPR.

Abdomen↗
PubMed1984

Reproducibility and accuracy of left ventricular ejection fraction and wall motion determinations using gold-195m: a new ultrashort-lived radionuclide for cardiac studies.

Gold-195m has a halflife of 30.5 sec. Its ultrashort halflife and low radiation exposure (240 mrads to the kidney from a 20-mCi injection) make it an ideal agent for sequential first-transit studies of cardiac function. The reproducibility of ejection fraction and wall motion determinations were assessed from two gold-195m first-pass angiograms performed 3 min apart in 38 subjects. The accuracy of these evaluations was assessed by performing another first-transit study using technetium-99m. The correlation of the ejection fraction between the two gold-195m angiograms was 0.95 (standard error of the estimate (SEE) = 0.049) over an ejection fraction range of 20-78. The correlation of the ejection fraction using technetium-99m versus gold-195m was 0.95; SEE = 0.050. Only six minor discrepancies were noted when wall motion was evaluated in the gold-195m angiograms and compared with the technetium-99m study. We conclude that gold-195m can provide repeated, accurate, and reproducible ejection fraction and wall motion determinations with conventional imaging equipment at a substantially lower radiation exposure than with technetium-99m.

Angiography↗
PubMed1984

Left ventricular function at rest and during Raynaud's phenomenon in patients with scleroderma.

We evaluated left ventricular function in 10 scleroderma patients with signs and symptoms suggestive of congestive heart failure. M-mode and two-dimensional echocardiography demonstrated normal to increased systolic function in all patients. The presence of pulmonary venous congestion on the chest radiograph was not useful in assessing left ventricular systolic function. Five of nine patients with normal to increased left ventricular ejection fraction (LVEF) had increased cardiothoracic ratios and increased pulmonary vascular markings. Left ventricular hypertrophy was associated with a worse New York Heart Association functional class, more pulmonary vascular congestion, and greater left atrial size. In the presence of normal systolic function and ventricular hypertrophy, diminished left ventricular diastolic compliance may account for the cardiac dysfunction in these patients. Cold pressor testing induced peripheral Raynaud's phenomenon in nine of nine patients; however, no ST segment changes or chest pain was provoked. In seven of nine patients there was no abnormal fall in LVEF. The mechanism for the fall in ejection fraction seen in two patients may be related to an increase in afterload or myocardial ischemia secondary to coronary atherosclerosis. We found little to suggest that a myocardial Raynaud's phenomenon affects left ventricular perfusion or systolic function. Clinical signs and symptoms of congestive failure as well as chest radiographs are poor indicators of impaired systolic function in scleroderma patients. Based on these findings, it appears that evaluation of left ventricular systolic function should include echocardiographic or angiographic study before such patients are treated for heart failure with inotropic agents.

Adult↗
PubMed1984

Cardiopulmonary resuscitation research 1960-1984: discoveries and advances.

The 24-year history of cardiopulmonary resuscitation (CPR) can be divided into four eras. The first (1960-1962) was the era of serendipitous discovery and description of "closed-chest cardiac massage" by Kouwenhoven and colleagues. Closed-chest heart massage was combined with artificial ventilation, and became known as CPR. The second (1962-1968) was the era of skepticism, in which CPR was challenged by investigators whose observations of hemodynamics were not in concert with the proposed mechanism of blood flow. The equality of arterial and central venous pressures during chest compression seemingly belied the proposed mechanism of blood flow during CPR, and raised questions about the effectiveness of the technique. The third era (1968-1976) was one of acceptance and complacency. The effectiveness had become established through widespread use in coronary care units, catheterization laboratories, and prehospital emergency systems, and open-chest cardiac massage was completely supplanted by CPR in virtually every resuscitation effort. The current era (1976-present) is the era of rediscovery and refinement, beginning with the observation that blood flow and pressure can be generated during cardiac arrest by coughing ("cough CPR"), without actual compression of the chest or heart, and that augmentation of arterial pressure and carotid blood flow resulted from simultaneous compression and ventilation (SCV-CPR or "new CPR"). The current era has provided a new explanation of the mechanism of blood flow during CPR and alternative methods of maintaining perfusion during cardiac arrest.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Circulatory support during cardiac arrest using a pneumatic vest and abdominal binder with simultaneous high-pressure airway inflation.

Animal and clinical studies suggest that blood flow during closed-chest cardiopulmonary resuscitation (CPR) results from phasic intrathoracic pressure fluctuations produced by rhythmic sternal depressions rather than from cardiac compression. Using physiologic observations made in animals and human beings during circulatory collapse and vigorous coughing, a pneumatic thoracic vest garment and abdominal binder device has been designed to emulate "cough CPR." Hemodynamic findings and microsphere regional perfusion observed during cardiac arrest and airway/vest/binder inflation are comparable to those observed during simultaneous chest compression and pulmonary ventilation CPR (SCV-CPR). Resuscitation and survival using the device has been compared to survival rates using conventional closed-chest CPR. The vest/binder apparatus significantly improved the coronary perfusion gradient and survival. Further studies are in progress to determine the clinical utility of this promising resuscitation adjunct.

Abdomen↗
PubMed1984

External non-invasive cardiac pacing: a comparative hemodynamic study of two techniques with conventional endocardial pacing.

Out-of-hospital therapy for cardiac arrest due to bradyarrhythmias or asystole is pharmacologic and the outcome is uniformly dismal. Optimal therapy for the latter disturbances may be artificial cardiac pacing, but conventional invasive pacing techniques are not employed or are of limited value in the out-of-hospital and emergency department setting. This investigation compared the hemodynamic effects of two techniques of non-invasive external pacing: 1) transcutaneous transthoracic pacing (TTP) and 2) tongue-to-epigastrium pacing (TEP), with conventional transvenous right ventricular endocardial pacing (RVEP) in a closed-chest, chronic heart block canine model. All techniques significantly increased (p less than .001) cardiac output (CO). However, CO and mean arterial pressure (MAP) measured during external pacing with either non-invasive technique were significantly greater than that during RVEP (p less than .001). TEP produced vigorous skeletal muscle stimulation and, in the canine model, it produced contraction resulting in impaired ventilation, hypoxemia, and a decrease in systemic vascular resistance. TTP in this model resulted in improved MAP and CO when compared with control and RVEP values and did not affect arterial or mixed venous blood gas values. Thus, this study demonstrates that noninvasive TTP is comparable to RVEP in its hemodynamic effects. TTP may offer definitive non-invasive therapy for a subset of victims of out-of-hospital cardiac arrest.

Animals↗
PubMed1983

Estimation of mixed venous oxygen saturation.

Pulmonary artery oxygen saturation (PA) was measured directly and estimated from venal cavae samples in 175 adults without intracardiac shunts to ascertain which of four formulas (MV1, MV2, MV3, or MV4) best estimated mixed venous oxygen saturation. Because the formula MV1, which favored IVC samples, most closely approximated pulmonary artery saturation, we recommend its use to estimate systemic flow in patients with left-to-right shunts. In addition, a difference between directly measured PA and calculated MV1 of 6% or greater indicates the presence of a left-to-right shunt in 97% of cases.

Adolescent↗
PubMed1982

Postmyocardial infarction angina and coronary spasm.

Coronary spasm can cause chest pain, and may even culminate in a myocardial infarction, but it is not often considered a cause of chest pain in the early postinfarction period. Three patients who had chest pain early (1 day to 3 weeks) after myocardial infarction were shown to have coronary spasm with ergonovine maleate provocation. Two patients had spasm in the coronary artery associated with the acute infarction; the third had spasm in a remote vessel. Two required intracoronary nitroglycerin to establish patency in the affected vessel. It is concluded that coronary vasospasm can result in postinfarction angina.

Adult↗