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R G Hahn

Publications and source records attributed to R G Hahn.

At least 145 records · Page 8Linked to original sources
PubMed1993

Dose-dependent half-life of glycine.

The serum concentration of glycine was measured at hourly intervals after administration of between 10 and 91 g glycine to 17 patients undergoing transurethral resection of the prostate and of between 15 and 22 g glycine to 18 volunteers by intravenous infusion. The apparent half-life of glycine varied 10-fold (range 26-245 min) and increased in direct proportion to the amount of glycine given. This result can be explained by assuming a marked intracellular accumulation of a surplus of glycine. The dose-dependent half-life means that patients who absorb large amounts of irrigating fluid are exposed to excessive blood levels of glycine for a prolonged period of time.

Absorption↗
PubMed1993

Patterns of irrigating fluid absorption during transurethral resection of the prostate as indicated by ethanol.

The absorption of irrigating fluid was measured by the ethanol method every 10 minutes during the course of 700 transurethral prostatic resections. The total blood loss was also measured using a photometer method. We found that ethanol determination is a convenient method of monitoring irrigating fluid absorption in daily practice. Absorption in excess of 150 ml. was detected in 46% of the operations. The volume of irrigant absorbed increased with the weight of the removed prostatic tissue, operating time and blood loss. The uptake of fluid usually started midway through the operation. Once absorption had started, there was an 87% probability that it would continue through the next 10 minutes with the exception of the last 10 minutes of surgery, when there was a 67% probability. A sudden decrease in arterial pressure coincided with the onset of fluid absorption 3.7 times more often than expected by chance. The absorption was no different in the 114 patients with a cancerous histology, compared to those with benign prostatic hyperplasia.

Absorption↗
PubMed1993

Intracerebroventricular infusion of glycine stimulates vasopressin release in conscious sheep.

We have previously observed that elevation of the plasma glycine concentration stimulates vasopressin (AVP) release in man and sheep. In the present study we show that this effect of glycine can be elicited directly via a cerebral site of action in conscious sheep. Intracerebroventricular infusions of 0.05 and 0.15 M glycine solutions increased the plasma AVP concentration by 6 and 50 times, respectively, while no effect on water intake was observed. Hyperhydration did not block the stimulation of AVP release. No behavioural side effects, or changes in blood pressure, were observed in response to the infusions.

Analysis of Variance↗
PubMed1993

Blood glucose after ethanol monitoring of irrigating fluid absorption in transurethral surgery.

The purpose of this study was to assess the risk of alcohol-induced hypoglycaemia from the use of irrigating fluids containing ethanol in transurethral surgery. In the first part of the study, seven healthy male volunteers, aged between 26 and 36, received 1000 ml of irrigating fluid by intravenous infusion. The results confirm the existence of an alcohol-induced decrease in blood glucose when ethanol is given together with 1.5% glycine. In the second part of the study, 40 patients, between 56 and 88 years of age, underwent epidural anaesthesia and a transurethral resection of the prostate (TURP) in which the irrigating fluid used contained 1.5% glycine and either 1% or 2% ethanol. The results suggest that the use of ethanol-containing irrigating fluids is often followed by a slight reduction of the blood glucose level, but the magnitude of this change is too small to be of clinical importance.

Absorption↗
PubMed1993

Haemodynamics and fluid balance after intravenous infusion of 1.5% glycine in sheep.

With the aim of studying the pathophysiological background of the "TUR syndrome", we gave six conscious ewes an intravenous infusion of 57 ml/kg of 1.5% glycine solution over 40 min. Isotonic saline infusions served as controls. Central haemodynamics were monitored. The plasma concentrations of protein, K, Na and vasopressin, and plasma osmolality were measured repeatedly for up to 4 h. The urinary excretions of Na, K and osmoles were also followed. Both infusions caused an elevation of the mean arterial pressure. With glycine, the pressure increased from 93 +/- 4 to 112 +/- 12 mmHg (12.4 +/- 0.5 to 14.9 +/- 1.6 kPa) (mean +/- s.d.). The pulmonary capillary wedge pressure increased from 7 +/- 3 to 16 +/- 3 mmHg (0.9 +/- 0.4 to 2.1 +/- 0.4 kPa) and remained slightly elevated. The central venous pressure rose from 2 +/- 3 to 11 +/- 3 mmHg (0.3 +/- 0.4 to 1.5 +/- 0.4 kPa) but returned to baseline within 30 min after the infusion. Infusion of glycine resulted in a decrease in the plasma Na concentration from 144 +/- 3 to 114 +/- 4 mmol/l. The plasma osmolality decreased from 290 +/- 2 to 280 +/- 1 mosmol/l, and remained low. There was a median 6-fold increase in plasma vasopressin concentration, while saline did not elicit vasopressin release. Despite the absence of electrolytes in glycine solution, the urinary excretion of sodium amounted to 106 +/- 40 mmol. We conclude that i.v. infusion of 1.5% glycine solution in sheep causes a transient circulatory strain and natriuresis. Moreover, a vasopressin-mediated reduction of maximal water excretion contributes to persisting hypoosmolality.

Amino Acids↗
PubMed1993

Health status and the preoperative change in serum potassium concentration.

When evaluating preanaesthetic abnormal serum potassium (S-K) levels, the anaesthetist often relies upon blood tests performed on admission to hospital 1 or more days prior to surgery. However, the S-K is often altered between admission to hospital and the induction of anaesthesia. In this study, we examined the effects of health status and medication on the preoperative change in S-K concentration in 150 unselected elderly men awaiting urological operations. Oral daily medication was not given preoperatively on the day of surgery. One third of the patients showed a change of 0.4 mmol/l or more (range -1.1 to +1.2), with an increase as common as a decrease. Those on treatment with calcium-channel blockers or diuretics showed an increase in the S-K concentration in the preoperative period, while patients using oral antidiabetics showed a decrease. The use of beta-adrenoceptor antagonists was not a significant predictor of the change in S-K concentration. In conclusion, we found that alterations in serum potassium were common prior to surgery, but only a small fraction of this variance could be accounted for by health status and medication.

Aged↗
PubMed1993

Increased haemodilution in hypotension induced by epidural anaesthesia.

This study examined whether the increased haemodilution from fluid loading in patients who develop hypotension at the onset of epidural anaesthesia (EDA) can be explained by high-level blockade or by stress-induced elevation of the blood glucose concentration. In 20 men aged between 53 and 87, crystalloid volume loading was carried out with 10 ml.kg-1 b.w. and EDA was induced with mepivacaine 2% and adrenaline 1:200,000. Irrespective of the blood pressure reaction to the blockade, there was no change in blood glucose level. A strong linear correlation between haemodilution and arterial pressure was found, in spite of unchanged blood glucose levels, in 10 patients in whom EDA was induced with bupivacaine 0.5%, and in 10 patients who received spinal anaesthesia with tetracaine 1%. There was no correlation between the haemodilution and the extent of sensory analgesia. These results support the view that low arterial pressure alone triggers the increased haemodilution observed during EDA-induced hypotension.

Aged↗
PubMed1993

Absorption of irrigating fluid and height of fluid bag during transurethral resection of the prostate.

The purpose of this study was to examine the relationship between the static pressure and the absorption of irrigating fluid during transurethral resection of the prostate. We measured the absorption by the ethanol method in 550 operations during which the fluid bags were placed randomly at distances of 60-65, 70-75, 80-85 or 90-100 cm above the operating table. There was no difference in the volume of irrigant absorbed at different bag heights or any association between fluid height and absorption when different ranges of fluid absorption were analyzed. This suggests that irrigant absorption cannot be prevented by placing the fluid bags at a certain height within the range of 60 to 100 cm above the operating table.

Absorption↗
PubMed1993

Ethanol monitoring of extravascular absorption of irrigating fluid.

Ethanol monitoring is a method for the early detection of fluid absorption by the intravascular route during transurethral prostatic resection. An analysis was made to determine whether ethanol detection could also be used to quantify extravascular absorption. The concentration-time profile of ethanol in the breath was analysed in 13 men aged between 57 and 80 years with extravasation of 860 to 3600 ml of an irrigant containing glycine 1.5% and ethanol 1%. The results showed that the volume of irrigant absorbed could be predicted from the persistently elevated breath ethanol level at the end of surgery. This prediction had a median deviation of 22% from the value obtained by careful volumetric measurement.

Absorption↗
PubMed1993

Reliability of clinical assessment of fluid absorption in transurethral prostatic resection.

We evaluated 5 frequently used clinical methods of assessing absorption of irrigation fluid during 118 transurethral prostatic resections. The use of an irrigating solution containing glycine 1.5% and ethanol 1% and subsequent analysis of the alcohol concentration in the exhaled breath (ethanol monitoring) served as control method. Most cases of fluid absorption in excess of 1,000 ml could be indicated from a combination of clinical observations made by the surgeon and the anaesthetic nurse, and by measuring the serum sodium concentration. 'False alarms' were common, however. The volumetric fluid balance did not accurately reflect absorption. We conclude that none of the routine methods alone was specific enough to suffice for detection of irrigation fluid.

Absorption↗
PubMed1993

Intraperitoneal absorption of irrigating fluid during endometrial resection.

We report a situation where uterine perforation was followed by uptake of 4,540 ml of irrigating fluid into the peritoneal cavity during transcervical resection of the endometrium. The irrigating fluid contained 1.5% glycine and 1% ethanol. There was a seven-fold increase in serum glycine level during the resection, which was stopped after 40 min because ethanol had repeatedly been detected in the patient's expired breath. Diagnosis of the intraperitoneal absorption was made from the pattern of ethanol changes and confirmed by surgical drainage of the absorbed fluid, which was performed before serious symptoms developed.

Absorption↗
PubMed1993

Transurethral resection syndrome from extravascular absorption of irrigating fluid.

An analysis was made of the clinical course of 20 transurethral resections of the prostate performed under epidural analgesia in which between 676 and 3,600 ml of irrigating fluid containing glycine had been absorbed by the extravascular route. Symptoms consisted in arterial hypotension (n = 14), postoperative oliguria (n = 11), nausea (n = 10), bradycardia (n = 7), abdominal discomfort (n = 5) and visual disturbances (n = 2). There was a significant correlation between hypotension and postoperative oliguria. The hyponatraemia at the end of the operation was only one third of the values obtained if the same amount of irrigating fluid had been absorbed by the intravascular route. Suprapubic drainage of the absorbed fluid (n = 8) did not reduce the hyponatraemia and prolonged the postoperative stay in hospital. Diuretics is an alternative to surgical drainage in all but the most severe cases of extravasation, but should be postponed until normovolaemia is restored and the circulation is stable.

Aged↗
PubMed1993

Blood loss during transurethral resection of the prostate as measured by the HemoCue photometer.

Blood loss was measured with the portable HemoCue photometer and the absorption of irrigating fluid was assessed by the ethanol method during 700 transurethral resections of the prostate. The blood loss ranged between 10 and 3,825 ml (median 300 ml). The weight of the resected prostatic tissue and the operating time were independent predictors of the amount of blood lost. General anaesthesia (n = 82) and malignant histology (n = 114) were associated with a smaller blood loss. In the patients who were given regional anaesthesia (n = 618), an mean systolic blood pressure of 100 mmHg or less resulted in a smaller bleed. Large-scale irrigating fluid absorption was typically associated with a blood loss of medium size and ranged between 500 and 1,000 ml. The incidence of such absorption was negligible in the patients in whom the blood loss per gram of resectate was less than 10 ml/g. Blood loss was also measured every 10 min during the course of another 110 operations, from which 20 patients with operating times in excess of 60 min were selected. Our analysis showed that no excessive blood loss occurred after 60 min of surgery.

Absorption↗
PubMed1993

Cooling effect from absorption of prewarmed irrigating fluid in transurethral prostatic resection.

Thirty patients were studied over 10-min periods in the course of transurethral prostatic resection with measurements of rectal temperature and fluid absorption. Glycine with or without ethanol was used as the irrigant. The changes in the body temperature as reflected in oesophageal and rectal measurements in 5 of the patients were almost identical. Seven of the 30 patients became hyponatraemic and absorbed an average of 1328 ml of glycine solution. They had a significantly greater drop in rectal temperature than patients with little or no fluid absorption. This cooling effect occurred despite prewarming of the irrigant medium to 37 degrees C, which can be explained by a decrease in fluid temperature when the bag is being emptied. It was concluded that absorption of irrigating fluid is a mechanism that promotes heat loss during transurethral operations.

Absorption↗
PubMed1993

Blood volume at the onset of hypotension during TURP performed under epidural anaesthesia.

An analysis was made of the development of hypotension in the course of 60 transurethral resections of the prostate (TURP) performed under epidural anaesthesia. Hypotension was defined as a decrease in the systolic pressure down to 85 mmHg or less, or a total drop of 60 mmHg or more within 15 min. Indirect estimations of the blood volume according to the haemoglobin dilution method indicated that patients who developed hypotension from the epidural anaesthesia had a larger decrease in blood volume than other patients. During the operation, hypotension was associated with a blood volume of 300 ml or more below baseline, while 400 ml above baseline was required to ensure a stable circulation when the legs were lowered and removed from the stirrups after the TURP. Low central venous pressures, which were measured in 30 of the patients, were also associated with hypotension during and after TURP. There was a significant linear relationship between the total changes in blood volume and CVP measured at the end of each 10-min period of TURP (P < 0.001). However, no correlation between heart rate and hypotension was found.

Aged↗