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Biomedical subjects

J E Chelly

Publications and source records attributed to J E Chelly.

At least 55 records · Page 3Linked to original sources
PubMed1991

Effects of enflurane and isoflurane on hepatic and renal circulations in chronically instrumented dogs.

Seven dogs were chronically instrumented for measurements of mean aortic blood pressure and cardiac output and for simultaneous measurements of hepatic, portal, and renal blood flows. Each animal was studied on two separate occasions, awake and during 1.2, 1.4, 1.75, and 2.0 MAC isoflurane and enflurane. Both anesthetics induced tachycardia; to a greater degree than isoflurane, enflurane lowered mean aortic blood pressure in a dose-dependent manner (-37, -45, -48, and -62% vs. -19, -25, -41, and -44%, respectively) and cardiac output (-20, -26, -41, and -48% vs. -3, -5, -11, and -15%, respectively). With isoflurane, cardiac output decreased only at 1.75 and 2.0 MAC, and portal blood flow did not change significantly, whereas hepatic arterial blood flow increased at 1.75 and 2 MAC (by 28 and 33%, respectively). With enflurane, no significant changes were recorded in hepatic arterial blood flow, whereas portal blood flow decreased in a dose-dependent manner. Except at 2 MAC, hepatic circulation did not differ between anesthetics. Likewise, neither anesthetic significantly changed renal blood flow, except for enflurane at 2.0 MAC, which was associated with a 35% reduction. Both anesthetics led to similar systemic, hepatic, and renal vasodilations. Our data suggest that high concentrations of enflurane are associated with decreases in portal, total hepatic, and renal blood flows, most likely as a result of an anesthetic-induced cardiac depression.

Animals↗
PubMed1991

Comparison of the effects of isoflurane and desflurane on cardiovascular dynamics and regional blood flow in the chronically instrumented dog.

Seven mongrel dogs were chronically instrumented for the measurement of aortic and left ventricular blood pressures, cardiac output, left ventricular wall thickening, left ventricular dP/dt, and circumflex coronary, renal, hepatic and portal blood flows under the influence of desflurane (D) and isoflurane (I). Administration of the two anesthetics, was randomized, as was the order of the concentrations administered. Each dog was studied awake and at 1.2, 1.4, 1.75, and 2.0 MAC of each anesthetic on different days. Both anesthetics decreased mean arterial pressure, stroke volume, systemic vascular resistance, left ventricular dP/dt, and wall thickness. The decreases were dose-dependent for mean arterial pressure (percent of awake values: D 78, I 85 at 1.2 MAC, and D 67, I 69 at 2.0 MAC); stroke volume (D 66, I 72 at 1.2 MAC, and D 52, I 57 at 2.0 MAC); dP/dt (D 61, I 64 at 1.2 MAC, and D 46, I 49 at 2.0 MAC); and WT (D 68, I 70 at 1.2 MAC, and D 47, I 60 at 2.0 MAC). Systemic vascular resistance decreased approximately the same at 1.2 MAC (D 71, I 87%) as at 2.0 MAC (D 71, I 79%). Heart rate increased but also not in a dose-dependent fashion (percent of awake values: D 177, I 145 at 1.2 MAC, and D 176, I 155 at 2.0 MAC). Coronary blood flow was increased by both anesthetics at all concentrations (percent of awake values: I 136 at 1.2 MAC and 161 at 2.0 MAC of awake, and D 131 at 1.2 MAC and 138 at 2.0 MAC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

An ultrasonic method for measuring tissue displacement: technical details and validation for measuring myocardial thickening.

We have developed a method for measuring myocardial thickening from a single ultrasonic transducer attached to the epicardium. Displacement of the underlying myocardial tissue is measured by following the phase of the echoes within a sample volume range-gated across the myocardium. The output is in the form of an analog signal. To verify the accuracy, resolution, and limitations of the system, we derived the equations relating the position of a reflector to the phase of its echo and compared the system output in vitro to a known input using a single moving target and a random distribution of scatterers, and in vivo to that of an ultrasonic transit-time dimension gauge. The results demonstrate that the 10 MHz system can accurately follow the motion of single or multiple targets with a resolution of 0.02 mm. In 25 dogs myocardial thickening measured with the displacement system compared favorably in both waveform and magnitude with thickening measured by the two-crystal transit-time method. Applications for the displacement method include: quantification of regional ventricular function in animal models of cardiovascular diseases, measurement of endocardial to epicardial differences in the deformation of regional myocardium during the cardiac cycle, and evaluation of regional cardiac function in patients during and after corrective cardiac surgery.

Animals↗
PubMed1990

An accurate, nontraumatic ultrasonic method to monitor myocardial wall thickening in patients undergoing cardiac surgery.

Measurement of systolic wall thickening by sonomicrometry provides an accurate index of regional left ventricular function, but the trauma of crystal insertion limits its widespread clinical use. The first clinical application of a 10 MHz ultrasonic Doppler probe that can be either sutured or applied by suction to the epicardium and can measure wall thickening at any depth of the left ventricular wall is described. In 18 dogs, measurements obtained with the suction probe correlated well (r = 0.97) with those of a previously validated sutured probe. To assess clinical feasibility, the probe was applied to the epicardium of patients undergoing coronary bypass surgery. Good quality wall thickening signals were obtained with no complications. Transmural left ventricular thickening fraction before bypass surgery was 34 +/- 3% (mean value +/- SE) at the mid-ventricular lateral wall, 33 +/- 4% at the anterior basal wall and 26 +/- 4% at the mid-ventricular posterior wall. Right ventricular thickening fraction averaged 25 +/- 3%. Endocardial thickening fraction tended to exceed epicardial thickening fraction, although the difference attained statistical significance (p less than 0.05) only at the anterior basal wall. On average, thickening fraction during the immediate postoperative period remained unchanged compared with the preoperative values, but a marked individual variability was observed, with 7 of 15 patients exhibiting a decrease and 8 an increase. Exteriorization of the wires attached to the sutured probe allowed continuous in situ monitoring of wall thickening in the postoperative period and subsequent removal of the probe. In six patients the crystal was left in place for 48 to 72 h after surgery and then removed without complications; good wall thickening signals were obtained for the entire period during which the probe was implanted. Thus, the Doppler probe is an accurate, atraumatic method for measuring right and left ventricular regional function. Transmural, endocardial and epicardial function can be mapped at various sites during surgery, and post-operatively one can monitor serial changes of regional function and assess the effects of cardioplegia and other therapeutic interventions. This technique should be useful for both investigative and clinical purposes.

Adult↗
PubMed1990

Cardiovascular effects of acute changes in extracellular ionized calcium concentration induced by citrate and CaCl2 infusions in chronically instrumented dogs, conscious and during enflurane, halothane, and isoflurane anesthesia.

To study the cardiovascular effects of low blood ionized calcium ion concentrations [Ca2+] induced by citrate infusion followed by high [Ca2+], induced by CaCl2 infusion awake and during enflurane (2.5% ET), halothane (1.2% ET), and isoflurane (1.6% ET) anesthesia, dogs were chronically instrumented to measure heart rate, aortic, left atrial, and left ventricular (LV) blood pressures, and cardiac output. In conscious dogs low [Ca2+] (decreased 0.35 mM); increased heart rate (HR) and mean aortic pressure (MAP) and decreased stroke volume (SV) and LV dP/dtmax. Low [Ca2+] increased HR during all three anesthetics and decreased LV dP/dtmax except during isoflurane anesthesia. Low [Ca2+] produced more hemodynamic depression during enflurane anesthesia than during anesthesia with halothane or isoflurane increasing left atrial pressure and decreasing MAP and SV. The differences seen were partially related to decreased systemic vascular resistance during halothane and isoflurane anesthesia. In conscious dogs following high [Ca2+] (increased 0.37 mM); only MAP and LV dP/dtmax increased. LVdP/dtmax was also increased by high [Ca2+] during all three anesthetics without a change in MAP. Cardiac output increased during halothane and isoflurane anesthesia but was unchanged during enflurane. It would appear that the hemodynamic sensitivity for the effects of changing [Ca2+] was enflurane greater than halothane greater than isoflurane greater than awake. The results suggest that the effects of changes in [Ca2+] induced by citrate and CaCl2 infusion are modified by the three volatile anesthetics.

Anesthesia, Inhalation↗
PubMed1990

Effects of sevoflurane and isoflurane on cardiac and coronary dynamics in chronically instrumented dogs.

To assess the hemodynamic properties of the new inhalational anesthetic sevoflurane, 22 dogs were chronically instrumented for measurement of heart rate, aortic, left ventricular and left atrial pressures, cardiac output, and coronary blood flow. Dogs were randomly assigned to two groups, receiving either 1.2 and 2 MAC of sevoflurane (n = 11) or isoflurane (n = 11). At 1.2 and 2 MAC, sevoflurane produced an increase in heart rate (+60 +/- 12% and +54 +/- 9%, respectively), dose-dependent aortic hypotension (-22 +/- 4% and -38 +/- 4%, respectively), systemic vasodilation (-22 +/- 5% and -19 +/- 5%, respectively), dose-dependent decrease in stroke volume (-31 +/- 6% and -48 +/- 4%, respectively), and left ventricular dP/dt (-40 +/- 4% and -61 +/- 10%, respectively). Cardiac output decreased only at 2 MAC (-17 +/- 6%). Finally, coronary blood flow increased at 1.2 MAC of sevoflurane (+29 +/- 8%). Except for heart rate, sevoflurane and isoflurane produced similar effects. At 1.2 MAC, sevoflurane produced a greater increase in heart rate than isoflurane (+60 +/- 12% vs. +33 +/- 9%). The authors conclude that, except for heart rate, the effects of sevoflurane on cardiac function and coronary blood flow are almost identical to those induced by isoflurane in the chronically instrumented dog.

Anesthetics↗
PubMed1990

Influence of hypertension on MAC of halothane in rats.

This study was designed to assess the relationship between MAC and hypertension. To this purpose, MAC of halothane was determined in fully inbred spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). Because MAC determination was performed in animals whose lungs were mechanically ventilated, the adequacy of the ventilation was initially established in 20 rats equally divided into SHR and WKY, and instrumented with catheters in the abdominal aorta. Subsequently, MAC of halothane was determined in 40 rats equally divided into SHR and WKY, including those instrumented. There were no differences in MAC of halothane between SHR (n = 20) and WKY (n = 20) (1.08 +/- 0.02% vs. 1.11 +/- 0.02%). Subgroup analysis indicated that MAC of halothane was not affected by the presence of an arterial catheter in the abdominal aorta (SHR 1.09 +/- 0.06% vs. 1.08 +/- 0.02%; WKY 1.15 +/- 0.04% vs. 1.08 +/- 0.02%). The authors' data provide experimental evidence that MAC is not affected by either chronic hypertension or limited instrumentation.

Anesthesia, Inhalation↗
PubMed1990

Effects of prostaglandins and the autonomic nervous system on the vasodilatory properties of nitroglycerin in conscious dogs.

This study was designed to assess the respective roles of prostaglandins and the autonomic nervous system in the responses to nitroglycerin (NTG) in conscious dogs. In vivo, NTG (1, 10, and 100 micrograms/kg i.v.) induced dose-dependent decreases in blood pressure and increases in heart rate and cardiac output. Coronary and carotid blood flows increased simultaneously, whereas responses in renal blood flow were biphasic, i.e., an initial decrease was followed by an increase above control at 10 and 100 micrograms/kg. NTG responses were not changed by indomethacin but were affected by chlorisondamine alone or in combination with indomethacin; tachycardia was abolished, and increases in cardiac output after 10 and 100 micrograms/kg were reduced by 26 and 32%, respectively, after ganglionic blockade and by 19 and 32%, respectively, after chlorisondamine plus indomethacin. In addition, increases in carotid blood flow in doses of 100 micrograms/kg were reduced by 88% after chlorisondamine and 83% after chlorisondamine plus indomethacin. Finally, in the presence of chlorisondamine plus indomethacin, NTG induced a more pronounced hypotension associated with a more pronounced renal vasodilation at the highest dose. Independent of indomethacin pretreatment, NTG in vitro induced a dose-dependent relaxation of the carotid, coronary, and renal arteries. Depending on the vascular bed, the reflex and local controls of circulation are affected differently by NTG.

Animals↗
PubMed1990

Effect of gender in centrally induced angiotensin II hypertension in dogs.

This study was designed to investigate the relation between gender, an endogenous inhibitor of the Na+-K+ pump, and volume-dependent hypertension induced by stimulation of the brain renin-angiotensin system and increased salt intake. Angiotensin II (20 ng/min i.c.v.) was infused for 4 weeks in five dogs of each sex with saline as the drinking fluid. In male dogs, angiotensin II induced parallel pressor (30%) and dipsogenic responses (70%), whereas no hypertension and no increase in fluid intake were observed in females. In contrast, the activity of the Na+-K+ pump as assessed by 86Rb uptake was independent of gender. Our data provide novel evidence that gender plays a determining role in the physiological properties of centrally administered angiotensin II.

Angiotensin II↗
PubMed1989

Cardiovascular effects of and interaction between calcium blocking drugs and anesthetics in chronically instrumented dogs: VII. Verapamil and thiopental.

To assess the role of basal anesthesia in the negative inotropic properties of verapamil, the effect of thiopental (30 mg/kg followed by 3.5 mg.kg-1.min-1) on verapamil pharmacokinetics (200 micrograms/kg iv; n = 6) and its pharmacodynamics (3 and 6 micrograms.kg-1.min-1; n = 11) in chronically instrumented dogs was studied. In the presence of thiopental, verapamil pharmacokinetics remained essentially unchanged. In contrast, anesthesia altered verapamil hemodynamic properties. In the conscious animal verapamil infusions increased heart rate (14 +/- 3 and 27 +/- 4 beats/min, respectively), cardiac output (0.22 +/- 0.07 and 0.24 +/- 0.08, l/min, respectively) and PR interval (14 +/- 2 and 25 +/- 6 ms, respectively) and slightly decreased dP/dt (-315 +/- 114 and -419 +/- 106 mmHg/s, respectively). Systemic vascular resistance (SVR) decreased at the low dose (-2.7 +/- 0.7 mmHg.1.min-1), and stroke volume decreased at the high dose (-4.4 +/- 0.6 ml). Yet the presence of thiopental resulted in an accentuation of verapamil-induced tachycardia (27 +/- 7 and 31 +/- 6 beats/min, respectively), and a decrease in stroke volume (-5.3 +/- 2.0 and -6.3 +/- 2.1 ml, respectively). At 3 micrograms.kg-1.min-1 verapamil did not increase PR interval, cardiac output, or vasodilation. Finally, at 6 micrograms.kg-1.min-1 verapamil did not decrease dP/dt and increased renal blood flow (21.8 +/- 6.4 ml/min). These data provide evidence that the negative inotropic properties of verapamil are more pronounced in the presence of thiopental. However, the role of basal anesthesia appears to be limited.

Animals↗
PubMed1988

Cardiovascular effects of and interaction between calcium blocking drugs and anesthetics in chronically instrumented dogs. VI. Verapamil and fentanyl-pancuronium.

To assess the interaction between verapamil and fentanyl-pancuronium, dogs were chronically instrumented to measure heart rate; PR interval; aortic, left ventricular, and left atrial pressures; and coronary, carotid, and renal blood flows. The effect of fentanyl citrate infusion on single-dose verapamil pharmacokinetics was examined in six animals. The effects of verapamil infusion (3 micrograms.kg-1.min-1 and 6 micrograms.kg-1.min-1) were examined in the conscious state and during fentanyl infusion plus pancuronium on two separate occasions in nine dogs. In addition, the effects of fentanyl citrate (500 micrograms.kg-1 followed by 1.5 micrograms.kg-1.min-1) were examined over 1 h of infusion. Fentanyl infusion did not affect single-dose verapamil pharmacokinetics. In the conscious animals, verapamil increased heart rate and PR interval, and slightly decreased LV dP/dt. Fentanyl combined with pancuronium increased mean arterial pressure and LV dP/dt. During fentanyl infusion, verapamil decreased mean arterial pressure and LV dP/dt, increased PR interval, and did not change heart rate. The hemodynamic effects of fentanyl infusion were steady over 1 h. In contrast to the inhalational anesthetics, which alter verapamil pharmacokinetics and have mainly additive effects with verapamil on left ventricular contractility, cardiac conduction, and regional blood flows, fentanyl-pancuronium had no effect on verapamil pharmacokinetics and minimal effect on verapamil pharmacodynamics in healthy dogs.

Animals↗
PubMed1988

Regional blood flows and cardiac function changes induced by angiotensin II in conscious dogs.

Hemodynamic properties of angiotensin (ANG) II 1, 5, 10 and 100 ng/kg i.v. and 10, 100 and 1000 ng/kg i.v.t. were assessed in conscious dogs. ANG II i.v. produced a dose-dependent pressor response (59 +/- 5-124 +/- 16 mmHg) and renal vasoconstriction (1.3 +/- 0.4-96 +/- 32 mmHg/ml/min). Ganglionic blockade (chlorisondamine 2 mg/kg i.v.) diminished mean arterial responses without altering peptide effects on renal circulation. At the highest dose, ANG II i.v. induced cardiac stimulation: increased heart rate (75 +/- 4-115 +/- 6 beats/min), cardiac output (2.0 +/- 0.1-2.4 +/- 0.2 l/min), dP/dt (2308 +/- 181-2773 +/- 173 mmHg/sec) and coronary blood flow (49 +/- 10-96 +/- 23 ml/min). Although with chlorisondamine cardiac response was more pronounced, subsequent beta blockade abolished it. Concomitantly, an isolated increase in plasma epinephrine was recorded (63 +/- 8-1505 +/- 354 pg/ml). A pressor response (59 +/- 8-89 +/- 13 mmHg) and renal vasoconstriction (1.1 +/- 0.1-2.2 +/- 0.5 mmHg/ml/min) were also produced by ANG II i.v.t. at the highest dose. These centrally mediated changes were prevented by chlorisondamine. Our study demonstrates 1) i.v. ANG II-mediated pressor responses are dependent on direct and indirect components, the relative contribution of each being dependent on the regional circulation; ANG II i.v. also produced a biphasic cardiac response--an initial centrally mediated depression and a secondary stimulation dependent on epinephrine via cardiac beta receptors and 2) i.v.t. ANG II-mediated pressor effects are essentially indirect. Finally, no evidence was found to support the role of vasopressin in ANG II effects.

Angiotensin II↗
PubMed1987

Cardiovascular effects of and interaction between calcium blocking drugs and anesthetics in chronically instrumented dogs. IV. Chronically administered oral verapamil and halothane, enflurane, and isoflurane.

Dogs were chronically instrumented to measure aortic and left atrial blood pressures, left ventricular maximal rate of tension development (dP/dt), cardiac output, and carotid, coronary and renal blood flows. Measurements were taken with the animals awake and during steady-state low and high concentrations of halothane (1.2%, 2.4%), enflurane (2.4%, 4.0%), and isoflurane (1.6%, 3.0%) with and without at least 2 weeks of oral verapamil, 120 mg, three times per day. Plasma verapamil levels varied widely, with means of 500-700 ng X ml-1 in awake animals and lower (300-400 ng X ml-1) at the time of hemodynamic measurements during anesthesia. Chronic oral verapamil in awake dogs produced predominantly tachycardia. The hemodynamic effects of low-dose halothane and isoflurane before and after oral verapamil were unchanged except for decreased renal blood flow after oral verapamil and no coronary vasodilation nor tachycardia. However, left atrial pressure was increased and cardiac output and coronary blood flow were decreased by low concentrations of enflurane with oral verapamil compared to without. The combination of oral verapamil with low (clinical) doses of enflurane was more depressant to the cardiovascular system of healthy dogs than was the combination of verapamil and halothane or isoflurane.

Administration, Oral↗
PubMed1987

Cardiovascular effects of and interaction between calcium blocking drugs and anesthetics in chronically instrumented dogs. V. Role of pharmacokinetics and the autonomic nervous system in the interactions between verapamil and inhalational anesthetics.

To assess the role of both pharmacokinetics and the autonomic nervous system in the interaction between inhalational anesthetics and verapamil, dogs were chronically instrumented to measure heart rate, PR interval, dP/dt, cardiac output, and aortic blood pressure. In a first group of seven dogs, studied awake and during halothane (1.2%), enflurane (2.5%), and isoflurane anesthesia (1.6%), verapamil was infused for 30 min in doses calculated to obtain similar plasma concentrations (83 +/- 10, 82 +/- 6, 81 +/- 10, and 77 +/- 9 ng.ml-1, respectively). For the latter purpose, the infusion dose was 3 and 2 micrograms.kg-1.min-1 awake and during anesthesia, respectively, preceded by a loading dose of 200, 150, and 100 micrograms.kg-1, awake, during isoflurane, and halothane and enflurane, respectively. In awake dogs, verapamil induced an increase in heart rate (24 +/- 5 bpm) and PR interval (35 +/- 9 msec) and a decrease in mean arterial pressure (-5 +/- 2 mmHg) and dP/dt (-494 +/- 116 mmHg/s). Although plasma concentrations were similar in awake and in anesthetized dogs, the only statistically significant changes induced by verapamil were an increase in heart rate and a decrease in dP/dt during halothane and enflurane, while left atrial pressure increased only with enflurane. In a second group of six dogs, verapamil pharmacokinetics were determined in the presence and absence of a ganglionic blocking drug (chlorisondamine, 2 mg.kg-1 iv). Blockade of ganglionic transmission resulted in a decrease in both initial volume of distribution and total clearance of verapamil--changes similar to those previously reported with inhalational anesthetics.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics↗
PubMed1987

Vasodilator properties of prostacyclin after coronary artery bypass surgery.

The vasodilatory properties of prostacyclin were studied in 12 intubated patients who underwent coronary artery bypass surgery. When infused in doses of 2.5, 5, 10, and 20 ng/kg/min, prostacyclin produced a dose-dependent decrease in systemic vascular resistance from 2,702 +/- 143 to 1,654 +/- 106 dynes/cm5/m2 (p less than 0.05). Heart rate, right atrial pressure, and pulmonary arterial and capillary wedge pressures did not change. Cardiac function was improved, since stroke volume index increased from 29.5 +/- 1.4 to 35.5 +/- 2.0 ml/min/m2 (p less than 0.05) and the rate pressure product decreased from 13.3 +/- 1.3 to 10.9 +/- 0.9 X 10(3) mm Hg/beats/min (p less than 0.05), while stroke work index remained unchanged. These hemodynamic changes were associated with a dose-dependent decrease in arterial oxygen tension which occurred from 278 +/- 25 to 133 +/- 22 mm Hg; however, oxygen transport increased as a result of the prostacyclin-induced increase in cardiac index. This study demonstrates that prostacyclin is a potent arterial vasodilator that may be of interest in the treatment of postoperative vasoconstriction occurring after coronary artery bypass surgery.

Adult↗
PubMed1987

Acute central effects of L-glutamate in pentobarbital-anesthetized dogs.

Microinjections of L-glutamate (10(-10) to 2 X 10(-8) mol/kg) into the nucleus of tractus solitarii produced a dose-dependent increase in mean arterial pressure and a decrease in heart rate. L-Glutamate-induced hypertension was prevented by spinal transection and pretreatment with atropine (1 mg/kg iv) reversed the bradycardia. L-Glutamate also produced a dose-dependent increase in mean arterial pressure when injected intravenously and into the cisterna magna, but the dose-effect curves were shifted to the right. Finally, pretreatment with hexamethonium (30 mg/kg iv) abolished the hypertension resulting from intravenous injections of L-glutamate. These data demonstrate that the nucleus of tractus solitarii may play a determinant role in the central pressor effects of L-glutamate. In addition, we demonstrated that this hypertension was due to a central sympathetic stimulation and that the autonomic nervous system also mediated the pressor effects of intravenous L-glutamate.

Anesthesia↗
PubMed1987

Continuous monitoring of mixed venous oxygen saturation during aortic surgery.

The correlation between mixed venous oxygen saturation (SvO2) and hemodynamic measurements was studied in 13 patients undergoing descending thoracic aortic aneurysm resection (DTAAR). A significant correlation (p less than 0.05) was found between cardiac index (CI) and SvO2 after the induction of anesthesia and at the end of surgery. However, no significant correlation could be found between SvO2 and CI during the most critical periods of the surgery that included the collapse of the left lung, the aortic clamping, and the aortic declamping. During DTAAR, continuous SvO2 monitoring is useful, but it cannot substitute for intermittent cardiac output and oxygen consumption (VO2) determinations.

Adult↗