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Biomedical subjects

G Silvay

Publications and source records attributed to G Silvay.

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

The effect of temperature, mean arterial pressure, and cardiopulmonary bypass flows on somatosensory evoked potential latency in man.

Median nerve somatosensory evoked potentials were recorded in 21 patients undergoing cardiac surgical procedures utilizing cardiopulmonary bypass, in order to establish the effects of hypothermia, reductions in mean arterial pressure, and alterations in cardiopulmonary bypass flows on evoked potential latency. Induction and maintenance of anesthesia with fentanyl caused a significant prolongation of latency of the first cortical peak. Temperature changes were linearly correlated with changes in latency for peaks recorded from Erb's point (r = -0.843, p less than 0.01) and the contralateral cortex (r = 0.843, p less than 0.01). There was no significant effect of mean arterial pressure or cardiopulmonary bypass flow reductions on latencies under the conditions of this study. Our results emphasize the importance of monitoring peripheral and first cortical peak latencies in evaluating somatosensory evoked potentials. It is suggested that peak latency prolongations beyond those predicted by temperature alterations may be indicative of hypoperfusion.

Adult↗
PubMed1980

Continuous ketamine infusion for one-lung anaesthesia.

The mechanism which normally affects distribution of blood flow through unventilated areas of the lung is hypoxic pulmonary vasoconstriction; this acts to divert the blood to well ventilated alveoli, resulting in a better ratio of ventilation to perfusion. Several reports have focused attention on the reduction or abolition of this reflex in the unventilated lung by most of the volatile anaesthetic agents used in clinical practice. This response was not abolished by the intravenous anaesthetic agents. One hundred and ten patients undergoing elective pulmonary resection were studied to evaluate the effect of a continuous infusion of ketamine during one-lung anaesthesia, by observing the changes in PaO2 as a reflection of shunt. Ketamine was chosen as the intravenous agent for its positive inotropic and chronotropic action. Additionally, by providing both analgesia and hypnosis, we were able to administer inspired oxygen concentrations of 50-100 per cent without concern that the patient might have recall for events during operation. We have demonstrated that in all cases a PaO2 in excess of 9.31 kPa (70 torr) was achieved with ketamine and FIO2 1.0 as well as an increase in shunt fraction from 25.9 per cent (FIO2 0.5) to 36.0 per cent (FIO2 1.0). We feel that ketamine provides a satisfactory alternative to the volatile agents for one-lung anaesthesia in patients where relative hypoxaemia might be unacceptable during operation.

Adult↗
PubMed1979

A comparison of the effects of continuous ketamine infusion and halothane on oxygenation during one-lung anaesthesia in dogs.

It has been shown that a continuous infusion of ketamine during one-lung anaesthesia combined with a 50 per cent oxygen-curare anaesthetic technique will provide consistently lower shunt fraction and higher Pao2 compared with halothane under the same experimental conditions. Because no additional factor was observed which could account for these changes and because the responses of the animals to the two anaesthetic agents were similar--the only difference being a different initial set point--the experimental model may be considered adequate. In the authors' view the difference in shunt fractions may be attributed to a more stable hypoxic reflex during ketamine anaesthesia. Further experimentation will be necessary to fully exclude the possibility of sequence-related changes affecting some of these results and to determine whether or not certain groups of dogs respond in a qualitatively different fashion.

Anesthesia↗
PubMed1978

[Microaggregate filters for blood transfusions].

Many types of microaggregate filter are now obtainable for use in blood transfusion. The aim, indication and potential advantage of microaggregate filtration for the patient are discussed. The Pall and Swank microaggregate filters are considered the filters of choice today, expecially with regard to the number of blood conserves which can be filtered.

Blood Transfusion↗
PubMed1978

The cerebral function monitor during open-heart surgery.

Open-heart surgery has entered the third decade of its existence. The period has demonstrated increased patient safety during and after open-heart surgery due to the employment of simple and reliable monitoring techniques. The monitoring of the function of the brain has not kept pace with these advances. Electroencephalographic (EEG) method is impractical for routine use in the operating room and in the intensive care unit. The cerebral function monitor (CFM) offers simplified continuous monitoring and interpretation of cerebral electrical activity (integrated EEG) in the clinical situation. The unit displays a two channel tracing, one representing cerebral activity and a second indicating electrode impedance artefacts. The early changes seen in addition to other conventional monitoring of the electrocardiogram, blood pressures, pulse rate, etc. offers information especially pertinent to open-heart surgery. It would appear that there is a place in anesthetic practice during and after cardiopulmonary bypass for the routine use of the CFM to supplement existing monitoring for the safer conduct of open-heart surgery. This study analyzes the value of a cerebral function monitor in 112 patients undergoing open-heart surgery.

Brain↗
PubMed1976

Use of a left heart assist device after intracardiac surgery: technique and clinical experience.

A left heart assist device (LHAD) has been employed in 14 patients. All had advanced heart disease and were in low cardiac output after repair, such that they could not be separated from cardiopulmonary bypass despite prolonged support and adjuvant therapy, including drugs, pacing, and use of intraaortic balloon counterpulsation whenever possible. Apart from special cannulas, the equipment necessary for the LHAD is widely available. An asset of the system (left atrial-ascending aorta bypass of the left ventricle) is that it may be terminated without reentering the thorax to remove the cannulas. This is accomplished with precisely fitting obturators that obliterate the cannula lumens and allow the tubes to be permanently implanted. This concept is believed important since critically ill patients requiring support are precisely those in whom added risk would be imposed by a second operation. Of the 14 patients who have had intraoperative and postoperative support (up to 6.8 days), 9 were weaned from the device and 6 were dismissed from the hospital. Four patients remain alive and are improved, the longest at 22 months since operation. The favorable performance of the LHAD suggests that it may prove useful either when intraaortic balloon counterpulsation cannot be successfully deployed or when it has failed to achieve hemodynamic stability.

Assisted Circulation↗
PubMed1975

Early clinical experiences with a heart assist device.

A method of left heart (left atrium-aorta) support after open heart surgery is described. Thoracic reentry is not required when support is terminated. The system has been employed in 10 patients, 4 of whom are long-term survivors.

Adult↗