Biomedical subjects

J H Arnold

Publications and source records attributed to J H Arnold.

9 recordsLinked to original sources

PubMed1992

Videothoracoscopy: improved technique and expanded indications.

Current videoendoscopic technology and percutaneous techniques of exposure and dissection have been successfully applied to abdominal surgery with favorable results. Application of this technology to our practice of thoracoscopy is the basis of this report. Videothoracoscopy has been performed in 39 patients for the following indications: chronic pleural effusion, interstitial lung disease, mediastinal lymphadenopathy in lung cancer, persistent air leak after decortication, mediastinal mass, recurrent spontaneous pneumothorax, hydropneumothorax with persistent air leak, and pleural-based mass. The technique we employ includes lateral decubitus positioning and double-lumen endotracheal intubation with ipsilateral lung collapse. The videoscope, retractors, and instruments are introduced through separate 10-mm incisions. Percutaneous manipulation of instruments and the videoscope is guided by images produced on television screens without dissection, and if resection is performed, the incision is enlarged to allow specimen retrieval. Procedures performed using this technique include pleural biopsy, partial pleurectomy, lysis of adhesions, lung biopsies, staging lymph node biopsy, lung nodule biopsy, pleural-based mass resection, and mediastinal mass biopsy and resection. This videoendoscopic technique greatly improves visualization of thoracic anatomy, facilitating thoracoscopy and enhancing exploration of the chest. It is preferred over conventional thoracoscopy and, in some patients, reduces the magnitude of operation by avoiding thoracotomy.

Adult↗

PubMed1992

Production of platelet thromboxane A2 and arterial prostacyclin I2 from hypercholesterolemic rats.

The plasma cholesterol, plasma malonaldehyde (MDA), platelet thromboxane A2 (TXA2) and vascular prostacyclin (PGI2) were measured in male Sprague-Dawley rats fed diets supplemented with cholesterol (1%) and cholic acid (0.5%). For comparisons, measurements were made in rats fed normal diets. The concentration of cholesterol in the plasma of rats had reached a maximum in 1 week of feeding experimental diets. TXA2 production from collagen and thrombin stimulated platelets was significantly decreased in animals fed experimental diets for 1 week. The production of MDA in the plasma of animals fed experimental diets for 8 weeks was significantly lower compared to the animals fed normal diets. There was a small but significant reduction in the formation of PGI2 in rats fed experimental diets for 8 weeks. These data suggest that feeding cholesterol rich diets to rats alters the platelet membrane properties differently from human and rabbit. Furthermore, cholesterol feeding to rats had some damaging effect on the arterial PGI2 synthesis.

6-Ketoprostaglandin F1 alpha↗

PubMed1992

Laparoscopic highly selective vagotomy.

Although the prevalence of peptic ulcer disease has not decreased, the number of surgical procedures for definitive treatment of peptic ulcer disease has diminished. While H-2 blockers are effective in healing ulcers, the incidence of recurrence, particularly in patients who have specific risk factors and do not use life-long maintenance therapy, may range from 50-90%. In an attempt to minimize the morbidity of definitive ulcer surgery, this study was undertaken to perform and evaluate highly selective vagotomy performed laparoscopically in the porcine model. Sixteen swine underwent laparoscopic highly selective vagotomy. The acute group (n = 10) underwent immediate celiotomy after the surgery. The chronic group underwent barium studies and celiotomy 6 months following surgery. In 70% of the acute group and 100% of the chronic group, nerve identification and division were accurate. Bleeding, when encountered, could be managed laparoscopically. In the chronic group, the postoperative weight gain was appropriate and barium studies were normal. This paper details the technique and results of laparoscopic highly selective vagotomy in an animal study and shows that this procedure can be safely and accurately performed. Based on this study, a clinical trial, which includes studies of acid production, long-term follow-up, and intraoperative endoscopic Congo red testing has been undertaken on recipients of laparoscopic highly selective vagotomy.

Animals↗

PubMed1991

Propagation of small bowel migrating motor complex activity fronts varies with anastomosis type.

Fasting small intestine motility (migrating motor complex or MMC) occurs in humans and dogs in four phases. Activity fronts during phase III consist of high amplitude contractions propagating aborally and are interrupted by transection of the small intestine. To study the effect of anastomosis type on MMC propagation six dogs underwent resection of a 15-cm segment of bowel 45 cm distal to the ligament of Treitz and single layer hand sewn end-to-end (EE) anastomosis. Single layer end-to-side (ES) or side-to-side (SS) anastomoses were hand sewn 15 cm distal to the transection in six other dogs. Eight force transducer strain gauges were placed at 10-cm intervals about each anastomosis. At least 7 days after operation, small bowel contractions were recorded in fasted animals, and recordings were visually inspected. Only 1 of 36 activity fronts propagated across the end-to-end anastomosis within 45 days of surgery. However, after 60 days 25 of 39 phase III activity fronts propagated. There was no propagation of MMC activity across the ES anastomosis and only 10% of activity fronts propagated across the SS anastomosis. We conclude phase III MMC activity front propagation is interrupted by small bowel transection. Propagation regenerates after EE anastomosis, but not after ES or after SS anastomoses, even after prolonged healing.

Anastomosis, Surgical↗

PubMed1991

Changes in the pharmacodynamic response to fentanyl in neonates during continuous infusion.

Tolerance to opioid-induced sedation has been reported in neonates sedated with fentanyl by continuous infusion while undergoing extracorporeal membrane oxygenation. We undertook a prospective analysis of eight newborn infants sedated with fentanyl during extracorporeal membrane oxygenation therapy for respiratory failure. We recorded daily mean fentanyl infusion rate, measured serial plasma fentanyl concentrations, and documented the occurrence of spontaneous motor activity or respiratory effort. Mean fentanyl infusion rate increased steadily during the period of infusion from a mean of 9.2 +/- 1.9 (SEM) micrograms/kg per hour on day 1 to a mean of 21.9 +/- 4.5 micrograms/kg per hour by day 6. Mean plasma fentanyl concentrations increased steadily during the period of fentanyl infusion from 3.1 +/- 1.1 (SEM) ng/ml on day 1 to 13.9 +/- 3.2 ng/ml on day 6. All infants exhibited movement in response to gentle tactile stimulation throughout the period of infusion, and seven of eight infants manifested spontaneous movement of the extremities and eye opening. Our results indicate that when fentanyl is used for sedation in neonates, the plasma concentrations required for satisfactory sedation steadily escalate, possibly indicating the rapid development of tolerance to the sedating effects of fentanyl.

Extracorporeal Membrane Oxygenation↗

PubMed1991

Variation in the size and number of stone fragments after gallbladder lithotripsy.

Ninety-four gallbladder ultrasound examinations were carried out in 11 patients at intervals for the first 40 days after lithotripsy. No dissolution or other active therapy was carried out during this time. Fragment size and number were measured to determine the postlithotripsy variability. Analysis of variance (ANOVA) showed no significant changes in fragment size or number over time. The changes in fragment size and number compared to the previous measurements were then evaluated. Again, ANOVA showed no significant changes between times. The average change in absolute size was 3.1 +/- 0.6 mm, and the average change in absolute number was 1.4 +/- 0.5. We conclude that fragment size and number as determined by ultrasound do not vary significantly with time during the first 40 days. The absolute size change measured to the nearest millimeter should be at least 4 mm to surpass the 95% confidence interval. Similarly, the absolute change in number should be at least 2 to be regarded as significant.

Analysis of Variance↗

PubMed1990

Tolerance and dependence in neonates sedated with fentanyl during extracorporeal membrane oxygenation.

We undertook a retrospective chart review of 37 neonates who received fentanyl by continuous infusion while undergoing extracorporeal membrane oxygenation (ECMO) between May 1986 and October 1988. We quantified the doses of all sedatives utilized, determined the incidence of neonatal abstinence syndrome (NAS), and identified risk factors associated with NAS. We determined peak fentanyl infusion rate, mean fentanyl infusion rate, total fentanyl dose, and duration of ECMO therapy. NAS was observed in 21 of 37 neonates (57%). In both the NAS and non-NAS neonates, mean infusion rate increased steadily during ECMO therapy, from a mean of 11.6 +/- 6.9 (SD) micrograms.kg-1.h-1 on day 1 to a mean of 52.5 +/- 19.4 (SD) micrograms.kg-1.h-1 by day 8. Total fentanyl dose and duration of ECMO were significantly greater in neonates with NAS. We found that neonates with a total dose greater than 1.6 mg/kg or an ECMO duration greater than 5 days had a significantly greater incidence of NAS (chi-squared test, P less than 0.01 and P less than 0.005; odds ratios = 7.0 and 13.9, respectively). With multiple logistic regression, ECMO duration was found to be the most powerful predictor of the occurrence of NAS. We also measured plasma fentanyl concentrations in a separate group of 5 neonates receiving fentanyl by continuous infusion for sedation. Fentanyl concentrations increased steadily during the period of infusion, suggesting the development of tolerance to the sedating effects. We conclude that continuous administration of fentanyl for sedation is associated with the uniform development of tolerance and a significant incidence of dependence. Alternative approaches to sedation should be investigated.

Drug Tolerance↗

PubMed1988

Splenorrhaphy for blunt trauma with a functioning distal splenorenal shunt: rationale and report of a case.

Splenorrhaphy was successfully performed following blunt abdominal trauma in a 42-year-old man with a functioning distal splenorenal shunt. The shunt had been created 16 months earlier for bleeding gastroesophageal varices (BGEV) secondary to alcoholic cirrhosis. Uniquely, this case brings into simultaneous focus the principles of selective shunting for BGEV and the technique and rationale of splenorrhaphy, while furthering the list of indications for the latter. Splenic preservation, including splenorrhaphy following trauma, is being increasingly advocated as the role of that organ in hematologic and immunologic homeostasis is further elucidated. Too, in that small segment of the population with portal hypertension, preservation of the spleen for use as a route of selective decompression for bleeding gastroesophageal varices has been emphasized. The following case illustrates splenic preservation toward accomplishment of both of these ends.

Abdominal Injuries↗

PubMed1985

Action of platelet-activating factor on type 1 diabetic human platelets.

Platelets from patients with type 1 diabetes have exhibited more sensitivity to aggregation when compared with platelets from controls without diabetes after challenge with platelet-activating factor (PAF). The production of thromboxane B2 (TxB2) and 12-hydroxyeicosatetraenoic acid (12-HETE) and the release of 5-hydroxytryptamine (5HT) were increased when the platelets were challenged by PAF (5.0 X 10(-6) mol/L and 1.0 X 10(-6) mol/L). The production of TxB2 and 12-HETE and the release of 5HT were related to the irreversible biphasic aggregation profiles observed in the patients with diabetes. Inhibition of thromboxane A2 (TxA2) production by acetylsalicylic acid abolished the secondary wave of aggregation of platelets from patients with diabetes, changing an irreversible aggregation to a reversible one. Inhibition of both TxA2 and 12-HETE production by eicosatetraynoic acid did not contribute further to the inhibition caused by acetylsalicylic acid alone, indicating that 12-HETE was not involved in the secondary wave of aggregation. These data show that the increased aggregation observed in the platelets from the group with diabetes in response to PAF results in part from their higher production of TxA2 and release of 5HT.

Adult↗