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R Muchada

Publications and source records attributed to R Muchada.

At least 37 records · Page 2Linked to original sources
PubMed1990

Conjugation and deamination of circulating dopamine: relationship between sulfated and free dopamine in man.

In order to assess the importance of conjugation in dopamine metabolism, we infused dopamine (20 nmol/kg/min, 1 h) to seven male subjects, then measured the kinetics of free and conjugated dopamine and DOPAC (deaminated dopamine) in plasma both during and after the infusion. Dopamine increased as early as 2 min after the start of the infusion, then reached a plateau and remained elevated on a level of 25 times the basal value. Dopamine sulfate and DOPAC followed very similar patterns and increased continuously from the 30th and 20th min, respectively, until the end of the infusion (5.18- and 5.76-fold, respectively), but only dopamine sulfate remained elevated (1.65-fold) on the first day following infusion. DOPAC glucuronide increased moderately (2.58-fold) at the end of the experiment, but neither dopamine glucuronide nor DOPAC sulfate were increased despite high precursor circulating levels. Free DOPAC and dopamine sulfate levels during infusion were correlated with dopamine levels when all subjects were pooled. In addition, within a subject dopamine sulfate to dopamine correlations were found with slopes varying in a range of 1 to 15. Our results show that sulfation is significantly involved in the metabolism of circulating dopamine and is not easily saturated, suggesting that dopamine sulfate may be an index of endogenous dopamine release.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

[Noninvasive hemodynamic monitoring via the integration of data obtained by ECG, aortic flow by Doppler esophageal probe and by finger plethysmography].

The aims of this work are to describe the general and technical characteristics of a new device for the noninvasive monitoring of patients in intensive care and during general anaesthesia, and the results concerning the reliability of this method. An ultrasonic esophageal probe and an echo-Doppler device have been used to obtain continuous data of the aortic diameter and of blood velocity. Aortic output is calculated automatically. This method, together with other non-invasive monitoring techniques (blood pressure, heart rate, rhythm and cardiac conduction), gives on the one hand the data of aortic output, systemic peripheral resistance and stroke volume; on the other, through a computerized elaboration, the systolic time intervals (PEP pre-ejection period, LVET left ventricular ejection time, QS2 electromechanical systole, PEP/LVET ratio of PEP to LVET). The validation of STI data, has been obtained through 125 comparative measurements for each of the three parameters. The data obtained through the aortic velocity waveform in descending aorta (pulsed Doppler) have been compared with those obtained through the aortic pressure waveform (intra aortic catheter). The correlation was: PEP 0.92, LVET 0.95, QS2 0.93. The clinical application of this method supplies data concerning cardiac load, after-load and indirectly cardiac pre-load. This non-invasive procedure gives us a continuous measurement of hemo-dynamic situation, which allows the physician to plan and evaluate the therapeutical efficacy. Finally new pathologic events may be opportunely faced.

Anesthesia, General↗
PubMed1990

[Non-invasive monitoring of hemodynamic profile during general anesthesia].

This article presents a general vision of a new non-invasive cardiovascular monitoring technique applied to patients during general anaesthesia. This method employs an esophageal eco-Doppler, able to supply a continuous measurement of the aortic diameter (eco-TM) and of the velocity of aortic blood flow (pulsed Doppler) for the calculation of aortic output; a monitor to survey the ECG and a noninvasive device for the measurement of blood pressure. The resulting data, opportunely processed by the computer, supply the values of aortic output, of systemic peripheral resistances and of stroke volume. The last two parameters are indexed with aortic output. Through the computer analysis of ECG and of the aortic velocity curve, it is possible to trace back the systolic time intervals and find out the left ventricular ejection time, the pre-ejection period and the electromechanical systole. All these values are indexed with heart rate. The validation of this method gave good results. The comparison between aortic output, measured by the eco-Doppler, and the value obtained with the thermodilution gave a correlation of r = 0.97, and comparing it with the one obtained with the electromagnetic ring, the correlation was r = 0.96. The aortic diameter was calculated with computerized tomography and the correlation between the two diameters resulted in 0.978. This method is quite useful because it supplies continuous parameters in an automatic and noninvasive way. Therefore it is possible, through a compete hemodynamic profile, to diagnose the variations and control the evolutions of the hemodynamic profile induced by the therapeutical treatments, on the basis of a correct physiopathological interpretation.

Anesthesia, General↗
PubMed1989

[Dobutamine during anesthesia of patients at risk for heart failure. A controlled prospective multicenter study of 93 surgical patients over 64 years of age].

Most anaesthetic agents cause cardiac depression possibly hazardous in the elderly, especially in presence of a poor cardiac reserve. Ninety-three patients undergoing non cardiac surgery lasting more than 90 min. were entered in a double-blind multicentre randomized trial. They were 65 year old or more and unaffected by evolutive angina pectoris. After insertion of a Swan Ganz catheter and an arterial cannula, anaesthesia was induced by thiopentone, fentanyl and 02/nitrous oxide (50%). Forty-five patients were infused dobutamine 7 micrograms.kg-1.min-1 (group D) from 10 min. after induction till the completion of surgery. Forty-eight patients received a placebo (group P). Haemodynamic parameters were recorded throughout anaesthesia and at its emergence. After induction, heart rate, pulmonary capillary wedge pressure and mean pulmonary artery pressure did not change significantly; mean arterial pressure, cardiac index, stroke index and left ventricular stroke work index decreased by 21, 33, 28 and 42% respectively (p less than 0.001); systemic and pulmonary arterial resistances increased by 12 and 37% respectively (p less than 0.001). In group P, these changes persisted throughout the procedure but, 30 min after extubation, cardiac index returned to control levels due to a 25% increase in heart rate; in this group 4 patients presented with both perioperative low cardiac output and persistent postoperative confusion. With dobutamine, haemodynamic parameters returned to preoperative values and heart rate increased by 12 b.min-1. More arrhythmias and hypertensive episodes but less hypotensions occurred in group D. Substantial haemodynamic changes occur during anaesthesia and surgery in elderly patients. Dobutamine corrects the peroperative decrease in cardiac output and blood pressure, and might prevent postoperative neurological disorders.

Aged↗
PubMed1986

[Noninvasive hemodynamic monitoring in gynecologic laparoscopy].

A new non-invasive haemodynamic monitoring technique was investigated on twenty female patients submitted to gynaecological laparoscopy under general anaesthesia. Continuous aortic output was measured with an echo-Doppler oesophageal probe specially developed by the authors. Peritoneal insufflation was performed with an average of 4 +/- 0.750 l CO2 at an average insufflation rate of 0.666 l X min-1; intraperitoneal pressure increased on average by 11.57 +/- 1.60 mmHg during insufflation. Aortic output changes were related to changes in the patient's position. In initial horizontal dorsal decubitus position, average aortic output was 2.83 +/- 0.642 l X min-1. Trendelenburg position (28 +/- 2 degrees) induced a transient 9.54% increase (p less than 0.05), while a return to the horizontal position was marked by an 11.3% increase (p less than 0.01) of the aortic output. No significant change was observed during insufflation and exsufflation (-2.13 and -5.3% respectively). Mean arterial pressure rose by 16.4% after insufflation (initial values: 90 +/- 15.08 mmHg; p less than 0.01). Total vascular systemic resistances were significantly higher at the end of insufflation (2.999 +/- 376 dyn X cm X s-5; + 18.04%; p less than 0.05). Heart rate did not change significantly. Aortic output monitoring with this non-invasive, easy-to-handle technique enabled early detection of haemodynamic changes during laparoscopy. These changes frequently preceded significant blood pressure or heart rate variations.

Adult↗
PubMed1986

[Dobutamine in vascular surgery].

The hemodynamic parameters of 12 patients operated on not a coronary vascular disease have been controlled by means of not invasive technic. The aortic output was measured by means of an oesophageal probe that associates echography and Doppler effect. A double blinded study was done by dividing the patients into two groups. The group 1 was subjected to a perfusion of dobutamine and the group 2 to a perfusion of a placebo during the operation. The group 1 showed a mean aortic output similar-level than before anesthesia one (3.40 +/- 0.61 l/min; 3.35 +/- 0.5 l/min) and 37% greater than group 2 (p less than 0.01), during operation period. The average systolic volume of group 1 was nearly similar at the initial one (46.5 +/- 12.92 ml; 40.8 +/- 8.2 ml) and 35% higher than group 2 (p less than 0.01). The cardiac frequency was higher (average 14 beats per minute) in the group 1 (p less than 0.01). The total systemic vascular resistance of group 1 were maintained in equilibrium and did not show any significative change. In opposition, group 2 showed a 207% increase in their vascular resistance, in relation to the initial values (p less than 0.01). These values were significatively higher that those of the group 1 (p less than 0.00). Mean diuresis was of 144 +/- 41.5 ml/h for group 1 and 43.6 +/- 10.9 ml/h for group 2 (p less than 0.001). In group 2 the H+ concentration increased from 33 to 39 nmol/l (p less than 0.01) and it was higher (p less than 0.01) than group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[Aortic flow measurement by transesophageal Doppler effect].

Continuous measurement of cardiac output by thermodilution is invasive, impractical and unpleasant for the patient. We propose to measure descending aortic blood flow with a specially designed intra-oesophageal Doppler echo probe. The apparatus is composed of two main parts. First an A scan system makes possible the measurement of the diameter of the vessel, second a continuous wave velocimeter is used to measure the spatial mean velocity of the blood. An output calculator determines the descending aortic blood flow. The oesophageal catheter contains three ultrasonic transducers at its tip mounted on an epoxy resin bracket produced by moulding. They are connected to a flexible hose placed inside a flexible polyvinyl sheath whose outer diameter is 6.8 mm and length is 50 cm. A cylindrical latex balloon is mounted on this sheath which is water inflated to minimum pressure, ensuring a good ultrasonic coupling between the transducers and the oesophageal wall. Connection between the probe and the apparatus is made by three coaxial cables. Three isolator-transformers are built into the connector cable to ensure a safe electrical circuit. After having bled the probe of any air, the balloon is deflated. The probe is gently introduced into the oesophagus by nasal or oral route until the transducers are situated between the 5th and 6th vertebra. The balloon is then inflated to minimum pressure with 10 ml of distilled water contained in a syringe. To find the aorta, the velocimeter is first used like a Doppler stethoscope. The probe is rotated into a position corresponding to the maximum level of Doppler signal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[Nicergoline to reduce intraoperative blood pressure increases in hypertensive patients].

In order to test the therapeutic action of nicergoline during peroperative arterial hypertension, an intravenous perfusion of 5 mcg/kg/mn average dose was given to 15 patients which presented a peroperative increase of Systolic Blood Pressure (SBP) greater than 30% when compared with preanaesthetic corresponding value. The haemodynamic evolution was monitored, using non invasive method (except for central venous pressure, CVP). Particularly Aortic Blood Flow (ASF) was measured by ultrasonic means using specially designed intraoesophageal probe and flow meter including A-Scan and Doppler Velocity meter. SBP increased in 43% during hypertensive peak (initial level mean 129, +/- 12.6 mmHg; hypertensive peak, mean 185 +/- 16.80 mmHg; p less than 0.001). Ten minutes after the beginning of nicergoline perfusion, SBP showed a significative decrease (mean 141.4 +/- 11.20 mmHg, +9%). At the end of operation the SBP was nearly to average initial value (mean 135, +/- 11.85 mmHg; +4.5%). Diastolic Blood Pressure and Mean Blood Pressure presented similar variations. ABF decreased significatively during hypertensive peak (Initial ABF value means 3.49, +/- 0.99 l/mn, hypertensive peak ABF value means 2.68, +/- 0.54 l/mn, -25%, p less than 0.01). Nicergoline perfusion induced a partial recovery of ABF (mean 3.23 +/- 0.56 l/mn, +8%, p less than 0.05). This one was confirmed at the end of operation (mean 3.6 +/- 0.56 l/mn; -4% N.S.). Heart rate did not change significantly during monitoring period. From this results is seems that nicergoline perfusion induces a protection of hypertensive patients during peroperative decompensation.

Adult↗
PubMed1979

Accidental amikacin overdose in man: emergency therapy by extrarenal dialysis.

Three accidental overdoses of amikacin (6, 6.5 and 8 times the normal dose) are reported. Emergency haemodialysis therapy was given and the serum levels monitored. No toxic effects were encountered. The need for such emergency haemodialysis seems to be limited to patients with impaired renal function or to cases where little time has elapsed between intake and detection of overdose.

Accidents↗
PubMedDate not supplied

Noninvasive aortic blood flow measurement using an intraesophageal probe.

The continuous measurement of cardiac output by the thermodilution technique is invasive, impractical and unpleasant for the patient. This paper describes the measurement of aortic blood flow with a specially designed intraesophageal echo Doppler probe. An A-scan unit allows the measurement of the diameter of the thoracic aorta and a continuous wave Doppler velocimeter is used for measurement of instantaneous blood flow velocity. In vitro experimental results as well as clinical studies are presented.

Aorta, Thoracic↗
PubMedDate not supplied

[Effect of dobutamine on the transport and consumption of oxygen during general anesthesia with enflurane].

We undertook a comparative study on the effects of dobutamine and placebo on hemodynamic parameters, O2 transport (DO2), O2 consumption (VO2, and acid lactic production during peripheral arterial surgery under general anesthesia with enflurane at a constant inspiratory concentration (1.2%). This study involved 18 patients older than 65 years (9 patients allocated in the dobutamine group and 9 in the placebo group). The hemodynamic course was monitorized by means of noninvasive methods such as the aortic output measured by continuous transoesophageal echo-Doppler. After introduction of enflurane into the circuit aortic output decreased by 39% in dopamine group and 36% in placebo. Total systemic vascular resistances increased by 52% in dopamine and by 48% in placebo treatment. DO2 showed a decrease of 39% in dopamine and 38% in placebo group. There were no appreciable differences in VO2 among the two groups. Recovery of hemodynamic parameters and DO2 was only observed in the dopamine group when the drug was perfused at a rate of 4 +/- 1.2 micrograms/kg/min. Dobutamine induced a transient increase of VO2 up to 225% of the baseline value. During the postanesthetic period VO2 and blood acid lactic were significantly higher in the dopamine than in the placebo group (192%, p less than 0.01 and 33%, p less than 0.05, respectively). The course of hemodynamic parameters, DO2, VO2, and blood acid lactic of dobutamine group appear to demonstrate that dobutamine perfusion reverts myocardial depression and improves cellular perfusion during general anesthesia with enflurane.

Aged↗