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Biomedical subjects

R G Hahn

Publications and source records attributed to R G Hahn.

At least 325 records · Page 18Linked to original sources
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Sensory and sympathetic block during interpleural analgesia.

BACKGROUND AND OBJECTIVES: Interpleural analgesia is an effective method for pain relief after upper abdominal surgery. To examine whether the analgesic effect is obtained by block of the intercostal nerves, we assessed the analgesic efficacy of the block, the skin sensitivity, and indices of sympathetic outflow over the trunk. METHODS: Interpleural analgesia was instituted at the end of open cholecystectomy in 20 patients 24-81 years of age (mean, 42 years). After a washout period of 8 hours, the analgesic effect was tested 5-12 times during the postoperative follow-up period by using a visual analogue scale before and 20 minutes after injection of 20 mL of bupivacaine 0.25%. Temperature and pain sensations were tested on the day after surgery, and in nine of the patients, the cutaneous blood flow over the trunk was studied by an electronic thermometer, laser Doppler flowmetry, and fluorescein flowmetry. In addition, the conduction velocity in the phrenic nerve was studied in four of the patients. RESULTS: Interpleural analgesia significantly reduced the median visual analogue score from of 5.7 (range 2-10) to 1.1 (range, 0-4). Although the analgesic effect was very good in all patients, half of them still showed skin sensitivity to pain and temperature. Cutaneous blood flow did not change, which showed than block of the intercostal nerves was incomplete. The phrenic nerve was not affected. CONCLUSION: The incomplete cutaneous sensory and sympathetic block indicates that the analgesic effect of interpleural analgesia cannot be explained by retrograde diffusion of the local anesthetic solution into the intercostal nerves alone.

Adult↗
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Pain relief by wound infiltration with bupivacaine or high-dose ropivacaine after inguinal hernia repair.

BACKGROUND AND OBJECTIVES: Wound infiltration with bupivacaine is often used for pain relief after inguinal hernia surgery. We hypothesized that the lower systemic toxicity of another long-acting local anesthetic of similar potency (ropivacaine) would make it possible to increase the dose to above that recommended for bupivacaine and thereby achieve more effective pain control. METHODS: Elective unilateral open hernia repair was performed on 144 patients at 4 hospitals. Surgery was performed under general anesthesia and, in a double-blind manner, the operating field was infiltrated with 40 mL ropivacaine 7.5 mg/mL (in = 73) or bupivacaine 2.5 mg/mL (n = 71 ) for postoperative pain relief. Pain at rest, on mobilization, and on coughing was assessed repeatedly during 24 hours using a visual analog scale. The patients' ability to walk and the need for supplementary analgesics were also recorded. RESULTS: No statistically significant differences were found between the two groups with respect to pain scores, which the patients reported to be less than 15% (median) of the worst pain imaginable in all examinations performed at rest, or in the consumption of supplementary analgesics. Those who received ropivacaine could walk with no or only minor problems at an earlier stage than the bupivacaine patients (P < .03). Both treatments were well tolerated. CONCLUSIONS: Wound infiltration with long-acting local anesthetics resulted in low pain scores after hernia surgery. Bupivacaine 100 mg was as effective as ropivacaine 300 mg.

Adult↗
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Volume kinetics of intravenous fluid therapy in the prehospital setting.

INTRODUCTION: To study the volume effect of isotonic and hypertonic crystalloid fluid during ambulance transports after mild trauma, a prospective case-control study was initiated, using the ambulance and helicopter transport system in Stockholm. METHODS: The hemodilution resulting from intravenous infusion of 1.0 L of Ringer's acetate solution (n = 7) or 250 ml of 7.5% sodium chloride (n = 3) over 30 minutes (min) was measured every 10 min during 1 hour when fluid therapy was instituted at the scene of an accident, or on arrival at the hospital. The dilution was studied by volume kinetic analysis and compared to that of matched, healthy controls who received the same fluid in hospital. RESULT: The hemodilution at the end of the infusions averaged 7.7% in the trauma patients and 9.1% in the controls, but the dilution was better maintained after trauma. The kinetic analysis showed that the size of the body fluid space expanded by Ringer's solution was 4.6 L and 3.8 L for the trauma and the control patients, respectively, while hypertonic saline expanded a slightly larger space. For both fluids, trauma reduced the elimination rate constant by approximately 30%. CONCLUSION: Mild trauma prolonged the intravascular persistence of isotonic and hypertonic crystalloid fluid as compared to a control group.

Adult↗
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Rupture of the myocardial histoskeleton and its relation to sudden death after infusion of glycine 1.5% in the mouse.

Hypoxic lesions in the subendocardium and long-standing dilatation of the interstitium have been described after exposure of the heart to glycine 1.5%, which is a widely used irrigating medium in endoscopic surgery. To study if the hypo-osmotic properties of the fluid cause these morphological changes, whether their long duration can be explained by rupture of the histoskeleton and whether they promote sudden death, 75 mice received an intravenous infusion of 200 ml/kg or 300 ml/kg over 60 min of either glycine 1.5%, glycine 1.5% in normal saline, normal saline, or no fluid (controls). The animals were decapitated when they were dying from the infusion, or else 7 days later, and 69 hearts were examined by light microscopy and 4 by electron microscopy. Rupture of the histoskeleton and hypoxic lesions in the subendocardium were observed in 47% and 35%, repectively, of the mice given glycine 1.5%, while the incidence averaged 20% in the two other groups. Rupture occurred in 38% of the mice that died, in 23% of those that survived an infusion, and in 0% of the controls. Hypoxic changes correlated with bradycardia, which is a sign of glycine absorption in the clinic. In conclusion, rupture of the histoskeleton and hypoxic changes occur in the subendocardium of mice after volume loading. These morphological changes were aggravated by the hypo-osmotic properties of glycine 1.5%.

Animals↗
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'Overshoot' of ethanol in the blood after drinking on an empty stomach.

The time required for ethanol to distribute between the systemic circulation and the rest of the body water results in an 'overshoot' of the blood-alcohol concentration (BAC) during the first 30 min after intravenous infusion. To investigate whether a similar distribution phenomenon occurs when ethanol is given by the oral route, we compared BACs after intravenous infusion and oral intake under strictly controlled conditions by giving a 0.4 g/kg dose of ethanol over 15 min to six fasting female volunteers. The results show an 'overshoot' in three volunteers who had the shortest time to BACmax, which indicates rapid absorption, and the time-course was similar to the distribution phase seen during the intravenous experiments. We conclude that BAC is sometimes higher than expected shortly after alcohol has been ingested rapidly. This finding can probably be explained by the fact that ethanol is distributed more slowly throughout the total body water than it is absorbed from the gut.

Adult↗
PubMedDate not supplied

High-dose ropivacaine wound infiltration for pain relief after inguinal hernia repair: a clinical and pharmacokinetic evaluation.

BACKGROUND AND OBJECTIVES: Early data on ropivacaine, a recently introduced local anesthetic, indicate a longer duration of skin analgesia than with bupivacaine, along with lower toxicity. The objective of this study was to evaluate ropivacaine 7.5 mg/mL for wound infiltration pain relief after hernia surgery, in higher doses than used before, in an open, nonrandomized design. METHODS: Twenty otherwise healthy men underwent elective unilateral open hernia repair by the same surgeon. General anesthesia was used during surgery, and infiltration of the operating field with 300 mg (n = 10) or 375 mg (n = 10) ropivacaine, 7.5 mg/mL, was employed for postoperative pain relief. Any sign of an adverse event was recorded. Plasma concentrations of ropivacaine were monitored. Pain at rest and on mobilization was regularly assessed over 24 hours by a visual analog scale. Patients' ability to walk and void and the need for supplementary analgesics were recorded. RESULTS: No serious adverse effects occurred. Plasma concentrations showed large variations but no toxic levels. No significant differences between the two groups were detected in pain scores which were low in both groups, at rest or on mobilization, or in the consumption of supplementary analgesics. At 4 hours, 19 patients were able to walk. Within 8 hours of surgery, all patients had passed urine without any problem. Wound healing was normal. CONCLUSIONS: Infiltration of ropivacaine 7.5 mg/mL during hernia surgery can be employed safely in doses of 300 mg and 375 mg to control pain after hernia surgery. The lower dose is recommended, since the higher one did not give any clinically relevant advantages.

Adolescent↗
PubMedDate not supplied

Short-term crystalloid fluid resuscitation in uncontrolled intra-abdominal bleeding in swine.

INTRODUCTION: Fluid therapy in uncontrolled bleeding is controversial. In a previously used experimental animal model of aortic injury, the outcome often was impaired by re-bleeding that began at least 20 minutes after crystalloid fluid resuscitation was initiated. Therefore, it was hypothesized that re-bleeding might be avoided if volume loading is carried out for 20 minutes and then discontinued. METHODS: Ten minutes after a 5 mm laceration was produced in the infra-renal aorta on eight anesthetized pigs, they received a 20-minute intravenous infusion of Ringer's solution in the ratio of 1:1 to the expected blood loss. Hemodynamics were studied for 120 minutes using arterial and pulmonary artery catheters and blood flow probes placed proximal and distal to the aortic lesion and around the left renal artery and portal vein. RESULTS: The bleeding stopped between three and four minutes after the onset of bleeding. The blood flow rate dropped to 38% (mean) of baseline in the splanchnic region, to 31% in the upper aorta, and to 13% in the kidney. The flow rates and the oxygen consumption increased transiently during fluid resuscitation, but never reached baseline levels. Re-bleeding amounted to about 15% of the initial bleeding and occurred in only three of the animals. Four of the pigs died of shock within 90 minutes (range 47-85 minutes) after the aortic injury. CONCLUSION: Short-term crystalloid fluid therapy in uncontrolled aortic hemorrhage transiently improved the hemodynamic status and the oxygen consumption following the initial bleeding. Furthermore, the infusion did not cause re-bleeding of more than 100 ml, which occurred in previously conducted experiments when the infusion was continued for more than 20 minutes.

Animals↗
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Adriamycin (NSC-123127) therapy for advanced gastrointestinal cancer.

Sixty-nine patients with advanced gastrointestinal carcinomas were given adriamycin intravenously at a dose level of 40-75 mg/m once every 3 weeks. Toxic effects included nausea, vomiting, diarrhea, stomatitis, alopecia, leukopenia, thrombocytopenia, and minor ECG changes. There was a slight trend toward move severe leukopenia in patients with markedly abnormal liver function test (serum glutamic oxaloacteic transaminase and alkaline phosphatase). Of the 57 pateints with colorectal cancer treated with adriamycin, four (7%) showed partial objective responses. In a controlled comparison of adriamycin versus 5-fluorouracil (5-FU) in patients with previously untreated large bowel carcinoma, three of 23 patients (13%) receiving adriamycin showed partial objective responses as compared with six of 25 patients (24%) receiving 5-FU. The median duration of response with adriamycin was 3 months com pared to over 6 months with 5-FU. Four of eight patients with gastric carcinoma showed partial objective responses. No responses were noted in a small number of patients with pancreatic and gallbladder carcinomas. Adriamycin would not seem to have any role in the treatment of advanced colorectal carcinoma. Our results, however, would justify further evaluation of this agent in gastric carcinoma.

Adenocarcinoma↗
PubMedDate not supplied

Cost-effectiveness of office obstetrical ultrasound in family practice: preliminary considerations.

This study reports costs incurred over a nine-and-one-half-month period following the introduction of obstetrical ultrasound into a group family practice serving primarily prepaid health plan patients. During this introductory period, 248 examinations were performed by family physicians and refereed by a radiologist for accuracy. The estimated cost to the practice was $95 per examination. This figure includes physician training expenses, professional fees, personnel, equipment and maintenance costs, costs for exams repeated due to technical error, and costs for additional consultation by a radiologist. Previously, all exams were referred to other consultants, and the charge was $185 per exam. Thus, in-office ultrasound exams performed by family physicians can provide cost savings while maintaining high standards of obstetric care.

Cost-Benefit Analysis↗