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Biomedical subjects

R G Hahn

Publications and source records attributed to R G Hahn.

At least 37 records · Page 2Linked to original sources
PubMed2001

Efficacy of subcutaneous and topical local anaesthesia for pain relief after resection of malignant breast tumours.

OBJECTIVE: Infiltration and topical application of local anaesthetics close to the surgical wound may be used to prevent postoperative pain. We evaluated the efficacy of these treatments after breast surgery for cancer. DESIGN: Double-blind randomised trial with two treatment groups and one control group. SETTING: University hospital, Sweden. INTERVENTIONS: Patients were allocated to treatment with bupivacaine infiltration (n = 29), topical application of lignocaine/prilocaine (n = 31), or no local treatment (n = 30). MAIN OUTCOME MEASURES: Difference and time related patterns in pain scores measured on a visual analogue scale (VAS), and morphine consumption. RESULTS. None of the local anaesthetics significantly reduced the VAS score or morphine consumption. However, fewer patients in the anaesthetic groups had high VAS scores than controls, the 75 centile for the mean score after operation being 2.7, 2.0 and 2.1 for the controls, infiltration, and topical anaesthetic groups, respectively. The controls had higher scores from 6 hours postoperatively onwards. The corresponding median morphine consumption was 24.5, 18.5, and 16.2 mg. CONCLUSIONS. Local anaesthesia slightly reduced the overall pain scores and the morphine consumption, but was of potential clinical value only in the patients who had the highest pain scores.

Administration, Topical↗
PubMed2001

Volume kinetics of Ringer's solution during induction of spinal and general anaesthesia.

The kinetics of an i.v. infusion of 20 ml x kg(-1) of Ringer's solution over 60 min was studied in patients undergoing spinal (n=10) and general (n=10) anaesthesia. The induction resulted in similar changes in volume kinetic parameters in both groups. When a one-volume model was employed (n=8), however, the infusion expanded a smaller body fluid space in the four patients who had received preoperative enteric lavage (3.3 vs 8.3 litres), which is consistent with hypovolaemia. When a two-volume model was statistically justified (n=12), the induction reduced the rate of fluid equilibration between a fairly small central (V1, mean 1.4 litres) and a peripheral body fluid space by about 50% (P<0.01). The kinetic analysis suggested that a rapid fluid load of 350 ml given over 2 min just after the induction could possibly prevent arterial hypotension because of central hypovolaemia. This was confirmed in five additional patients.

Adult↗
PubMed2001

Volume kinetics of glucose solutions given by intravenous infusion.

Glucose solutions given by intravenous (i.v.) infusion exert volume effects that are governed by the amount of fluid administered and also by the metabolism of the glucose. To understand better how the body handles glucose solutions, two volume kinetic models were developed in which consideration was given to the osmotic fluid shifts that accompany the metabolism of glucose. These models were fitted to data obtained when 21 volunteers who were given approximately 1 litre of glucose 2.5 or 5% or Ringer's solution (control) over 45 min. The maximum haemodilution was similar for all three fluids, but it decreased more rapidly when glucose had been infused. The volume of distribution for the infused glucose molecules was larger (approximately 12 litres) than for the infused fluid, which amounted to (mean (SEM)) 3.7 (0.3) (glucose 2.5%), 2.8 (0.2) (glucose 5%), and 2.5 (0.2) litres (Ringer). Fluid accumulated in a remote (cellular) body fluid space when glucose had been administered (approximately 0.2 and 0.4 litres, respectively), while expansion of an intermediate fluid space (7.1 (1.3) litres) could be demonstrated in 33% of the Ringer experiments. In conclusion, kinetic models were developed which consider the relationship between the glucose metabolism and the disposition of intravenous fluid. One of them, in which infused fluid expands two instead of three body fluid spaces, was successfully fitted to data on blood glucose and blood haemoglobin obtained during infusions of 2.5 and 5% glucose.

Adult↗
PubMed2001

Do ethanol and deuterium oxide distribute into the same water space in healthy volunteers?

BACKGROUND: The volume of distribution at steady state for ethanol (Vss) is thought to be identical to the total body water (TBW). We compared a two-compartment pharmacokinetic model with parallel Michaelis-Menten and first-order renal elimination with the classical one-compartment zero-order elimination model. Ethanol concentration-time profiles were established for breath, venous blood, and urine. The values of Vss obtained for ethanol were compared with TBW determined by deuterium oxide dilution. METHODS: Sixteen healthy volunteers each received a 30-min intravenous infusion of ethanol on two occasions. Ethanol was measured in breath by a quantitative infrared analyzer and in blood and urine by headspace gas chromatography. Deuterium oxide was given as an intravenous injection and measured in serum by isotope-ratio mass spectrometry. Components of variation were calculated by ANOVA to determine the precision of the estimates of Vss and TBW. RESULTS: Mean TBW, determined by deuterium oxide dilution, was 44.1 +/- 3.9 liters (+/-SD) for men, corresponding to 0.61 liters/kg, and 37.4 +/- 3.2 liters for women, or 0.54 liters/kg. Estimates of Vss from blood-ethanol pharmacokinetics were 87.6% of TBW according to isotope dilution and 84.4% for breath analysis with the two-compartment model. This compares with 95.1% and 95.4% for blood and breath alcohol, respectively, when the classical zero-order kinetic analysis is used. The precision of the estimates of Vss and TBW was between +/-1.56 and +/-2.19 liters (95% confidence interval). CONCLUSIONS: Ethanol does not distribute uniformly into the TBW. The precision of measuring Vss by ethanol dilution was comparable to estimates of TBW by isotope dilution. Results of noninvasive breath ethanol analysis compared well with use of venous blood for estimating Vss. The sophisticated two-compartment model was much superior to the classical one-compartment model in explaining the total concentration-time course of intravenously given ethanol.

Adult↗
PubMed2001

Acute hemodynamic effects of induced hypothermia in hemorrhagic shock: an experimental study in the pig.

Hypothermia (HT) is used in certain surgical procedures to reduce metabolism and protect the brain, but in trauma victims accidental HT is considered harmful. Recent animal studies indicate that HT has protective effects in hemorrhagic shock. The aim of the present study was to examine how induced HT modifies the hemodynamic pattern in hemorrhagic shock. Twenty pigs with a body weight of between 17 and 24 kg (mean 20.8) were anesthetized, 50% of their blood volume was withdrawn, and hypothermia (30 degrees C) was induced in half of them (HT group) while the others served as controls. Central hemodynamics was monitored during 4 h via an arterial line and a pulmonary artery catheter. Blood samples were obtained for measurement of leukocyte and platelet counts. Three of the control pigs died while all the animals in the HT group survived the experiment. The hemorrhage resulted in a marked increase in heart rate and a drop in cardiac output and mean arterial pressure. HT slowed the heart rate and induced a further reduction of cardiac output, which parallelled the depression of the core temperature, while the stroke volume did not change in any of the groups. A significant decrease in mean arterial pressure and the leukocyte count became apparent 2 h after the induction of HT. HT aggravated the hypokinetic situation resulting from hemorrhagic shock but without increasing the mortality.

Animals↗
PubMed2001

Smoking increases the risk of large scale fluid absorption during transurethral prostatic resection.

PURPOSE: We studied the association between smoking habits and absorption during transurethral prostatic resection in healthy patients, and in those with medical disease and prostate cancer. MATERIALS AND METHODS: Smoking habits and the presence of medical disease and prostate cancer in 1,034 patients who underwent transurethral prostatic resection were compared with fluid absorption levels. These levels were measured by the ethanol method and surgical blood loss, as determined by a photometer. RESULTS: The incidence of fluid absorption greater than 1,000 ml. was 15.7% in the present smokers, 15.5% in the past and present smokers, and 8.8% in those who had never smoked. Compared to nonsmokers, the relative risk of 1,000 to 2,000 ml. fluid absorbed in past and present smokers was 1.8 (95% confidence interval 1.1 to 2.9). The corresponding relative risk of absorption greater than 2,000 ml. was 2.1 (95% confidence interval 1.1 to 4.3), with the greatest excess risk in present smokers, which was 2.8 (1.3 to 5.9). These differences between smokers and nonsmokers were even greater in the healthiest patients, while being relatively smaller in those with medical disease or prostate cancer. Fluid absorption correlated with the amount of blood lost but the demonstrated association between smoking and fluid absorption (p <0.024) could not be explained by an effect on blood loss. CONCLUSIONS: Past and present smoking increases the risk of large scale fluid absorption during transurethral prostatic resection. A possible reason is that smoking alters vascular growth in the gland.

Aged↗
PubMed2000

Clinical outcome 1 year after transurethral vaporization and resection of the prostate.

OBJECTIVES: To evaluate the 1-year safety and effectiveness of transurethral vaporization of the prostate (TUVP) compared with transurethral resection of the prostate (TURP) in alleviating outflow obstruction. METHODS: Two experienced surgeons performed 26 TUVPs and 28 TURPs. The intraoperative blood loss was measured by photometry and fluid absorption by the ethanol method. The treatments were evaluated by means of the International Prostate Symptom Score (IPSS), quality-of-life score, transrectal ultrasound, prostate-specific antigen level, urinary flow rate, and postvoid residual urine volume. RESULTS: After TUVP, the median IPSS decreased from 22 to 4.5 and the quality-of-life score from 4.5 to 1.5. The corresponding data for TURP were from 25 to 5.5 and from 4.0 to 1.0. The median urinary flow rate increased from 4 to 10 mL/s after TUVP and from 2 to 11 mL/s after TURP. The postvoid residual urine volume decreased to 35% (TUVP) and 15% (TURP) of the preoperative volume. The blood loss was larger during TURP (P <0.04), but complications during follow-up were more frequent after TUVP (P <0.02). Patients with fluid absorption during surgery had a lower quality-of-life score at follow-up (P <0.02) and tended to have a smaller reduction in prostate size (to 79%) than those without absorption (to 67% of baseline). CONCLUSIONS: TUVP and TURP were both effective in alleviating outflow obstruction, but the outcome appeared to be slightly better for TURP.

Aged↗
PubMed2000

Incidence of acute myocardial infarction and cause-specific mortality after transurethral treatments of prostatic hypertrophy.

OBJECTIVES: Transurethral resection of the prostate (TURP) is associated with a higher long-term mortality than open prostatectomy which has been ascribed to a higher incidence of acute myocardial infarction (AMI). To assess the possible excess risk associated with TURP, we studied the incidence of AMI and the cause-specific mortality in patients treated with TURP and transurethral microwave thermotherapy (TUMT). METHODS: Patients treated for benign prostatic hypertrophy at a university hospital (888 patients with TURP and 478 with TUMT) were monitored during an average follow-up period of 3.9 years. The incidence of AMI and the causes of death were compared with those in the general population. RESULTS: Both treatments were followed by a higher incidence of AMI than in the general population, in particular from 2 years or more after treatment (standardized morbidity ratio 1.50, 95% confidence interval [CI] 1.14 to 1.93). The long-term mortality from all causes was increased in patients younger than 75 years of age when undergoing any of the treatments (standardized mortality ratio [SMR] 1.16, 95% CI 0.97 to 1.39), in particular, death from cardiovascular diseases (SMR 1.25, 95% CI 0.95 to 1.60) and tumors (SMR 1.54, 95% CI 1.14 to 2.03). CONCLUSIONS: The similarity of the results for TURP and TUMT suggests that the prostatic enlargement rather than the treatment is associated with cardiovascular disease.

Adult↗
PubMed2000

Within- and between-subject variations in pharmacokinetic parameters of ethanol by analysis of breath, venous blood and urine.

AIMS: To evaluate the prerequisites for using ethanol dilution to estimate total body water, we studied the within- and between-subject variation in the parameter estimates of a two-compartment model for ethanol pharmacokinetics with parallel Michaelis-Menten and first-order renal elimination. Because sampling of breath might be preferable in some clinical situations the parameter estimates derived from breath and venous blood were compared. METHODS: On two occasions, ethanol 0.4 g kg-1 was given by intravenous infusion to 16 volunteers after they had fasted overnight. The proposed model was fitted by means of nonlinear regression to concentration-time data measured in the breath, venous blood and urine during 360 min. The model contained six parameters: Vmax and Km (Michaelis-Menten elimination constants), CLd (intercompartmental distribution parameter), VC and VT (volumes of the central and tissue compartment, respectively) and CLR (renal clearance). The volume of distribution, Vss, was calculated as the sum of VC and VT. RESULTS: The mean +/- total s.d. of the parameter estimates derived from blood data were Vmax 95 +/- 25 mg min-1, Km 27 +/- 19 mg l-1, CLd 809 +/- 232 ml min-1, VC 14.5 +/- 4.3 l, VT 21. 2 +/- 4.4 l, CLR 3.6 +/- 2.0 ml min-1 and Vss 35.8 +/- 4.3 l. The variation within subjects amounted to 3%, 9%, 21%, 21%, 17%, 26% and 2%, respectively, of the total variation. Breath samples were associated with a similar or lower variation than blood, both within and between subjects. About 1.5% of the infused ethanol was recovered in the urine. CONCLUSIONS: The low within-subject variation of the key parameter Vss (only 2%) suggests that ethanol dilution analysed by the pharmacokinetic model applied here may be used as an index of the total body water. Breath samples yielded at least as good reproducibility in the model parameters as venous blood.

Adult↗
PubMed2000

Epinephrine, potassium and the electrocardiogram during regional anaesthesia.

Epinephrine lowers the serum potassium level through an effect on the beta2-receptor. It is therefore difficult to evaluate whether depression of the ST level and the T wave on the electrocardiogram, during regional anaesthesia, is caused by a high plasma epinephrine level, a low serum potassium level, or both. For this purpose, we studied the relation between electrocardiogram and the plasma epinephrine and serum potassium concentrations during 20 intra-abdominal operations performed under combined epidural and general anaesthesia and in 18 subjects receiving intercostal nerve blockade. The results show that the hypokalaemic effect of epinephrine was reduced when the plasma epinephrine concentration exceeded 3 nmol L-1. A multiple regression analysis demonstrated that the ST level and the T-wave amplitude were most consistently affected by a low serum potassium level, while a high plasma epinephrine level correlated only to a depression in the T-wave amplitude. During surgery, only serum potassium correlated with these ECG variables.

Abdomen↗
PubMed2000

The volumetric fluid balance as a measure of fluid absorption during transurethral resection of the prostate.

To evaluate the usefulness of the volumetric fluid balance for indicating and quantifying fluid absorption during transurethral resection of the prostate, 62 patients showing fluid absorption on ethanol monitoring (control method) were selected from a series of 410 operations. The volumetric fluid balance, which was measured as the difference between the input and output of irrigating fluid with and without a correction for the blood loss, proved to be an unreliable clinical tool for measuring the absorption. It indicated that fluid absorption occurred only in 40 or 18 of the 62 patients, depending on whether a correction for blood loss was made or not, the volume being only 59% and 71% (median), respectively, of that obtained by the control method. The absorption averaged 1 L in the patients in whom the volumetric measurements did not indicate absorption. The incidence of symptoms of the 'transurethral resection syndrome' increased with the absorbed fluid volume only when measured by the control method.

Aged↗
PubMed2000

Intravesical pressure during irrigating fluid absorption in transurethral resection of the prostate.

OBJECTIVE: In order to control fluid absorption, various approaches are used to reduce intravesical pressure during transurethral resection of the prostate (TURP). With a view to finding a target pressure for such efforts, pressure and fluid absorption were compared in a meta-analysis of four previous studies comprising three different irrigation techniques. MATERIALS AND METHODS: Intravesical pressure was recorded during TURP in which the irrigating fluid was evacuated intermittently (n = 48) by a suprapubic tube (n = 23) or a trocar (n = 30). Fluid absorption was compared with the mean and maximum pressures and the duration of excessive pressure (>2 kPa) over 10-min periods. RESULTS: Mean bladder pressure during fluid absorption was between 1.0 and 2.5 kPa. The maximum pressure during absorption varied greatly during the first 30 min of TURP, but thereafter it ranged between 2 and 3 kPa. Only the duration of pressures >2 kPa increased with fluid absorption (p < 0.02). The maximum pressures were highest with the intermittent technique, while the other indices of intravesical pressure showed the highest values when the suprapubic tube was used. The lowest pressures usually occurred when the trocar was used, but fluid absorption still occurred, as the pressure was much higher during some of these operations. CONCLUSIONS: Fluid absorption occurred at moderate intravesical pressures with all three irrigation techniques. The best strategy for reducing fluid absorption is to keep the pressure below 2 kPa for as long as possible during TURP.

Absorption↗
PubMed1999

Comparison of urological irrigating fluids containing glycine and mannitol in volunteers.

BACKGROUND: We compared symptoms and indices of fluid distribution after experimental administration of glycine and mannitol solutions, since these irrigating fluids are sometimes absorbed by the patient during genitourinary surgery. METHODS: Glycine 1.5% and mannitol 3%, both with ethanol 1% added, were given by intravenous infusion at a rate of 0.5 ml/kg/min during 30 min to 12 male volunteers. Symptoms, cognitive status, hemodynamics, electrocardiogram during 24 hr, computerized tomography of the brain, bioimpedance, blood chemistry, and breath ethanol concentrations were recorded. RESULTS: Glycine was associated with more symptoms than mannitol (P< 0.006), but the cognitive status, computerized tomography examinations, electrocardiograms, and breath ethanol concentrations did not differ between the solutions. The urinary excretion of fluid and sodium was greater after mannitol (P< 0.04), while only the glycine infusions hydrated the cells (P< 0.05). For both fluids, the intravascular and interstitial volumes were below baseline 3 hr after the experiment started (P< 0.01). CONCLUSIONS: Glycine 1.5% had a higher tendency than mannitol 3% to cause symptoms and to accumulate in the cells.

Adult↗
PubMed1999

Volume kinetics of Ringer solution after surgery for hip fracture.

PURPOSE: To study the time course of volume changes during and after infusion of Ringer's solution in elderly patients after a standardised trauma. METHODS: The kinetics of 12.5 ml.kg-1 Ringer's solution infused over 30 min were studied in ten patients one day after surgery for hip fracture (mean age, 70 yr) and in an age- and sex-matched control group. Hemodilution, as measured every five minutes for 90 min, was used to calculate the size of the fluid space expanded by the fluid (V) and the elimination rate constant (kr). The baseline fluid balance status in the patients and the controls was compared by bioelectrical impedance analysis. RESULTS: The size of V was 4.1 +/- 0.51 (mean +/- SEM) in the patients and 3.4 +/- 0.21 in the controls (P:NS) while the corresponding results for kr were 85 +/- 12 and 166 +/- 27 ml.min-1, respectively (P < 0.04). Bioelectrical impedance analysis showed that the extracellular fluid space and the total body water volumes did not differ between the two groups. Computer simulations based on the data obtained for V and kr indicate that trauma increases the dilution of the plasma volume and the retention of fluid in response to slow and moderate infusion rates, while these indices of short-term changes in fluid balance remain the same in the two groups during very rapid infusion of Ringer's solution. CONCLUSION: A slower elimination rate increased dilution of plasma and retention of fluid when Ringer's solution was infused in elderly trauma patients.

Aged↗
PubMed1999

Acute effects of vitamin A on the kinetics of endotoxin in conscious rabbits.

BACKGROUND: Vitamin A reduces the pathophysiological effects of endotoxin in animals, but the mechanism and the lowest effective dose are not clear. METHODS: An intravenous bolus of endotoxin 20 microg. kg(-1) was given to 30 rabbits. In 10 of them, 1000 IE. kg(-1) retinyl palmitate was injected intravenously 1 h before the endotoxin and in another 10 rabbits 1 h after the endotoxin. A one-compartment open model was fitted to the time-concentration profile of endotoxin in plasma. RESULTS: The half-life of endotoxin was half as long when vitamin A was given for prophylaxis (median 35 min) and for treatment (33 min) than in the controls (67 min; p < 0.004). The plasma concentrations of immunoglobulin G and M endotoxin-core antibodies, the leucocyte count and the acid-base balance did not differ between the groups during the experiment, but the pyrogenic reaction was more pronounced in the controls. CONCLUSION: A fairly low dose of vitamin A reduced the half-life of endotoxin.

Analysis of Variance↗
PubMed1999

Blood ammonia levels after intravenous infusion of glycine solution with and without ethanol.

OBJECTIVE: Absorption of glycine 1.5% during transurethral resection of the prostate may increase blood ammonia levels, but hyperammonaemia has not been described when the fluid also contained ethanol 1%. The aim of this experimental study was to evaluate whether ethanol 1% reduces glycine-induced hyperammonaemia. MATERIAL AND METHODS: Two intravenous infusions of glycine solution with and without ethanol 1% added were given on different occasions to 20 male volunteers (mean age 30 years). Half of them received 22 g of glycine over 50 min and the others approximately 18 g over 30 min. Blood ammonia was measured before and 30 min after the infusion. The serum levels of free amino acids were measured on 7 occasions during 10 of the experiments. RESULTS: The glycine infusions increased blood ammonia levels from 37 micromol/l (median, 10th and 90th percentile limits 34-53) to 57 micromol/l (27-110; p < 0.001). The change was greater after the larger glycine dose, regardless of whether the fluid contained ethanol (p < 0.05). The only amino acid concentration correlating with blood ammonia was glycine, which showed higher levels in those who had a rise in blood ammonia of 50% or more. CONCLUSIONS: Ethanol 1% did not reduce the increase in blood ammonia concentration after the administration of glycine solution.

Adult↗