Biomedical subjects

S Sapsed-Byrne

Publications and source records attributed to S Sapsed-Byrne.

14 recordsLinked to original sources

PubMed2000

Nerve tissue protein S-100 and neurone-specific enolase concentrations in cerebrospinal fluid and blood during carotid endarterectomy.

Nerve tissue protein S-100 and neurone-specific enolase levels in serum were studied in 10 patients before, during and for 2 days after elective carotid endarterectomy performed under general anaesthesia and using a Javid Shunt. In six patients, simultaneous cerebrospinal fluid samples were also obtained. Serum nerve tissue protein S-100 was normal throughout the operation, but in one patient with severe hypertension, levels increased to 1.38 microg. l-1 at 1 h postoperatively. Two patients showed an increase in cerebrospinal fluid nerve tissue protein S-100 during clamping: these patients also had neurological deficits at 6 months. Serum neurone-specific enolase increased from 5.8 to 9.3 microg.l-1 during shunting while cerebrospinal fluid neurone-specific enolase did not change. Uncomplicated carotid endarterectomy does not produce cerebral damage as measured by serum nerve tissue protein S-100; cerebrospinal fluid nerve tissue protein S-100 may be more sensitive for minor cerebral damage. Neurone-specific enolase appeared to be nonspecific. The lack of correlation between the neuroproteins may need to be explained before relying on these simple assays as diagnostic indicators of cerebral ischaemia.

Aged↗

PubMed2000

Sex and oestrous cycle differences in visceromotor responses and vasopressin release in response to colonic distension in male and female rats anaesthetized with halothane.

Visceromotor responses and vasopressin release before and after colonic visceral distension were compared between male (n=5 (n=4 for vasopressin)) and female rats and between females during the oestrous cycle (proestrus n=6, oestrus n=5, metestrus n=5, diestrus n=6) at a controlled depth of anaesthesia. Pre-stimulation vasopressin and blood pressures demonstrated oestrous cycle variability. The mean (SEM) colonic balloon pressure triggering visceromotor responses was significantly higher in males (64 (4) mm Hg) than females (41 (1) mm Hg), P=0.002 and within females, proestrus rats had the lowest thresholds, (29 (1) mm Hg, P<0.01). Post-stimulation, vasopressin concentrations increased significantly in all groups (males 1.34 (0.39) to 2.24 (0.74) pmol litre(-1); females 1.54 (0.24) to 2.88 (0.58) pmol litre(-1); P=0.002). Within groups statistically significant differences were measured in proestrus 2.06 (0.56) to 3.42 (1.12) and oestrus 1.16 (0.38) to 2.76 (0.60) pmol litre(-1) (P<0.05). High vasopressin concentrations coupled with low-pressure stimulation during proestrus shows sex-hormone dependent integration of the neuroendocrine response to noxious visceral stimulation.

Analysis of Variance↗

PubMed1999

Time course of neurone-specific enolase and S-100 protein release during and after coronary artery bypass grafting.

Serum neurone-specific enolase (NSE) and S-100 protein are well established as markers of cerebral injury, and have been used as markers of neuronal and glial cell damage, respectively, after cardiac surgery with cardiopulmonary bypass (CPB), but the speed of their increase during CPB has not been studied. Therefore, we have investigated the time course of NSE and S-100 release during and after CPB. We studied 18 adult patients undergoing elective coronary artery bypass grafting (CABG). Standard hypothermic (32 degrees C) pulsatile bypass with membrane oxygenation was used. Blood samples were obtained at induction, before bypass, before rewarming, at the end of rewarming, 10 min, 1 h and 8 h after bypass and 1, 2 and 3 days after surgery. NSE and S-100 were assayed using immunoradiometric assay kits (Sangtec Medical). NSE and S-100 release followed similar time courses. Both increased sharply during bypass, reached peak concentrations at the end of rewarming (mean 25.55 (SEM 2.79) and 1.65 (0.23) microgram litre-1, respectively), had decreased significantly by the end of operation and returned to pre-bypass concentrations by the second day after surgery. No patient developed a major neurological deficit. When using NSE and S-100 assays to study cerebral dysfunction in relation to CPB, postoperative samples miss peak (end-bypass) concentrations, and studies should be designed to include intraoperative samples.

Adult↗

PubMed1997

Neurone-specific enolase and Sangtec 100 assays during cardiac surgery: Part I--The effects of heparin, protamine and propofol.

Neurone-specific enolase (NSE) and Sangtec 100 (S-100) (Sangtec Medical, Sweden) assays are designed for clotted samples, but when studying cerebral damage following cardiac surgery, perioperative samples will contain heparin and/or protamine. The lipid emulsion propofol is also frequently used during cardiac surgery and could affect the assays. We, therefore, studied the effects of heparin, protamine and propofol on the accuracy of NSE and S-100 assays in five healthy patients. Blood samples were taken and divided into four groups: normal saline was added to group A; heparin to group B; heparin followed by protamine to group C; and propofol to group D. NSE and S-100 concentrations were measured for all samples. Neither heparin, protamine nor propofol affected the accuracy of S-100 and NSE assays; therefore, samples can be taken throughout operations involving cardiopulmonary bypass without influencing the results.

Anesthetics, Intravenous↗

PubMed1997

Neurone-specific enolase and Sangtec 100 assays during cardiac surgery: Part II--Must samples be spun within 30 min?

Sangtec 100 (S-100) (Sangtec Medical, Sweden) and neurone-specific enolase (NSE) assays are showing promise in the assessment of cerebral damage following cardiopulmonary bypass (CBP). The manufacturer's instructions state, however, that samples must be spun and frozen within 30 min, which is inconvenient for serial studies. We, therefore, investigated whether strong blood samples at room temperature (RT) or 4 degrees C for up to 48 h affected the measured levels. Blood samples were taken before and after CBP in six patients and stored for 15 min, 4, 8, 24 or 48 h at RT or 4 degrees C. S-100 and NSE levels did not alter in either 'before surgery' or CPB samples when stored for up to 48 h at 4 degrees C. There was a small, nonsignificant rise when stored at RT. Samples may, therefore, be collected throughout long operations or stored overnight without affecting NSE or S-100 plasma levels.

Blood Preservation↗

PubMed1997

Neurone-specific enolase and Sangtec 100 assays during cardiac surgery: Part III--Dose haemolysis affect their accuracy?

Neurone-specific enolase (NSE) and Sangtec 100 (S-100) are useful for detecting cerebral damage during cardiopulmonary bypass (CPB). However, red cells contain NSE, and the haemolysis frequently caused by CPB could produce a false rise in NSE; S-100 is not found in red cells and should not be affected. We, therefore, compared the effects of haemolysis on NSE and S-100 to see if correction was necessary and possible. From seven patients, serial dilutions of haemolysed red cells were added to plasma (1/64-1/2048), measured for absorption at 540 nm and assayed for NSE and S-100. S-100 concentrations showed no change with haemolysis. Measured NSE increased significantly with haemolysis > 1/512 (an increase of 6.6 micrograms/ml): a correction formula is presented. In 39/48 patients after CPB, mean haemolysis was < 1/256 and would not need any correction. NSE and S-100 assay can, therefore, be used throughout CPB, which allows both glial and neuronal damage to be studied.

Artifacts↗

PubMed1996

Estrous cycle phase variations in visceromotor and cardiovascular responses to colonic distension in the anesthetized rat.

Visceromotor and cardiovascular responses to colonic distension were measured in female rats, anesthetized with halothane in oxygen, in the proestrus, estrus, metestrus and diestrus phases of the estrous cycle. Ten rats were studied in each group and responses were measured at 5-min intervals for 60 min. A mixed model analysis of variance showed that there was no real change in either the visceral or cardiovascular response with time. There was a highly significant difference in visceromotor responses between the phases of the estrous cycle (P < 0.001). During the phase of proestrus the balloon pressure at which a response was triggered was much lower, with a mean value (95% confidence interval) of 18.7 (16.1, 21.8) mmHg, than the other phases with mean values (95% confidence interval) of 31.9 (27.4, 37.2) mmHg for estrus, 28.1 (24.2, 32.8) mmHg for metestrus, and 31.1 (26.7, 36.3) mmHg for diestrus. The mean arterial blood pressure increased in all groups (range 3.2, 5.4%) as a response to the stimulus, but there was no associated heart rate variability and no significant differences in cardiovascular changes between the groups (P = 0.6). The visceromotor responses measured during the phase of proestrus occurred at a significantly lower threshold than in the other phases of estrous.

Anesthesia↗

PubMed1995

Metabolic control of non-insulin-dependent diabetic patients undergoing cataract surgery: comparison of local and general anaesthesia.

We studied 40 elderly patients undergoing cataract surgery. Ten non-insulin-dependent diabetes mellitus (NIDDM) patients received standardized general anaesthesia, 10 NIDDM patients received local anaesthesia using retrobulbar block, 10 non-diabetic control patients received general anaesthesia and 10 non-diabetic controls received retrobulbar block. We measured sequential changes in blood glucose, lactate and beta-hydroxybutyrate, serum cortisol and insulin, and plasma non-esterified fatty acid concentrations until 4 h after operation. The results showed that in both general anaesthesia groups, NIDDM and control, blood glucose and serum cortisol concentrations increased significantly during surgery, before returning to normal by 4 h after operation; in both local anaesthesia groups, glucose and cortisol concentrations changed little during surgery. Serum insulin concentrations increased 30 min after operation to coincide with the peak of the glucose increase in the non-diabetic patients who received general anaesthesia, but no insulin response was seen in the diabetic general anaesthesia patients. Blood glucose and insulin concentrations increased in patients who received local anaesthesia (NIDDM and controls) when they ate after operation. The results show that cataract surgery under local anaesthesia provides improved metabolic control for the diabetic patient. Its use maintains glucose homeostasis, prevents the increases in cortisol and glucose which are seen under general anaesthesia and obviates the need for postoperative starvation.

Aged↗

PubMed1990

A new infant oscillatory ventilator.

A new, simple and inexpensive oscillatory ventilator is described in which a rotating jet mounted in the breathing duct generates cyclically positive and negative pressures in the airway with a sinusoidal flow waveform. Unlike conventional oscillatory ventilators it is free from restrictions to inspiratory or expiratory gas flows and open to atmosphere at all times, making it intrinsically a safe system for ventilation. A prototype rotating jet oscillatory ventilator designed for application in infants was evaluated in rabbits (mean weight 3.8 kg). The positive peak and mean airway pressures were significantly less during oscillatory ventilation at 300 and 420 b.p.m. compared with normal and high frequency positive pressure ventilation at 30 and 300 b.p.m., respectively, while maintaining blood-gas tensions within the normal range. An increase in the oscillatory frequency from 300 to 420 b.p.m. provided no further benefit in terms of airway pressure, tidal volume or blood-gas tensions.

Animals↗

PubMed1990

Local analgesia prevents the cortisol and glycaemic responses to cataract surgery.

We studied the metabolic and hormonal responses to cataract surgery in 18 elderly patients, allocated randomly to receive either general anaesthesia or local analgesia by means of a retrobulbar block. Local analgesia prevented the increases in circulating cortisol and glucose concentrations found in those patients who received general anaesthesia. The results show that complete afferent sensory block of the operative site inhibited endocrine and metabolic responses to ophthalmic surgery.

Aged↗

PubMed1989

Circulatory depression with high peep in the surfactant-deficient rabbit.

Surfactant depletion was induced by lung lavage in 10 rabbits. Ascending aortic blood flow was measured at normocapnia at 0, 5 and 10 cm H2O PEEP before and after lavage. Aortic blood flow was reduced by PEEP, by a maximum of 24% before lavage and 60% after lavage. It was concluded that, although adequate arterial oxygenation can be maintained with 10 cm H2O PEEP in surfactant-depleted rabbit's lungs, the circulatory impairment may result in inadequate oxygen delivery.

Animals↗

PubMed1988

Selective depression by alfentanil of group III and IV somatosympathetic reflexes in the dog.

The effect of alfentanil on sympathetic reflexes evoked by supramaximal electrical stimulation of the radial nerve has been observed in five dogs anaesthetized with alpha-chloralose, paralysed with suxamethonium and artificially ventilated. In five dogs during the infusion of alfentanil at a rate of 20 micrograms kg-1 min-1 the late long latency sympathetic response evoked by unmyelinated fibres (group IV, C) was abolished at a mean dose of 68.8 (SE 2.85) micrograms kg-1. The infusion rate was then increased to 200 micrograms kg-1 min-1 and the early, short latency response evoked by small myelinated fibres (group III, A delta) was eliminated at mean total dose of 809 (SE 72) micrograms kg-1. When the infusion was stopped the group III reflex returned within 1-5 min and recovery to approximately 50% of control for both reflexes occurred within 15-60 min in different preparations. Mean arterial pressure and mean heart rate decreased from 140 (6) mm Hg and 132 (11) beat min-1 to 100 (7) mm Hg and 70 (6) beat min-1, respectively, by the time the group IV response was eliminated; that is, after a mean infusion time of 3.4 min. Thereafter, there was no further cardiovascular depression. Within 3 min of the administration of naloxone 2 mg i.v., the sympathetic reflexes, arterial pressure and heart rate returned to within control values.

Action Potentials↗

PubMed1986

Combined continuous-flow, normal, and high-frequency ventilation.

Ten anesthetized, paralyzed dogs were ventilated at 10 breath/min and 100 cycle/min with a valveless ventilator. When fresh respiratory gas was supplied at the carina or insufflated into the bronchi, there was a significant (p less than .05) reduction in PaCO2, which was maximal during high-frequency ventilation (HFV) with twice normal minute volume. There was no statistically significant advantage in using a more complicated system for bronchial insufflation compared with supplying the fresh gas through a single tube near the carina. The improvement in ventilation and oxygenation during HFV with gas at the carina was reduced markedly when normal lungs were injured by oleic acid. Thus, when peak airway pressure was minimized during HFV, there was a further improvement in gas exchange without an appreciable increase in airway pressure when the gas was supplied at the carina.

Animals↗

PubMed1986

Selective effect of sufentanil on group III (A delta) and group IV (C) somatosympathetic reflexes.

The effect of sufentanil on somatosympathetic reflexes and the subsequent reversal of its effects by naloxone have been observed in dogs anaesthetised with alpha-chloralose, paralysed with suxamethonium and artificially ventilated. When the drug was infused at a rate of 2.5 micrograms kg-1 min-1 the late long latency response evoked by Group IV (C) fibres was totally abolished at a mean dose of 6.40 micrograms kg-1 (+/- 0.99 microgram kg-1) (s.e. mean), while retaining a substantial part of the early short latency response evoked by group III (A delta) fibres; subsequently, during the infusion, this response was also totally abolished at a mean dose of 26.2 micrograms kg-1 (+/- 3.2 mg kg-1). The administration of naloxone (2 mg i.v.) completely reversed the effects of sufentanil within 3-5 min in different preparations. Some of the implications of these results are discussed.

Animals↗