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Biomedical subjects

A Halverson

Publications and source records attributed to A Halverson.

6 recordsLinked to original sources
PubMed1998

Evaluation of mechanism of increased intracranial pressure with insufflation.

BACKGROUND: Previous studies have documented an increase in intracranial pressure with abdominal insufflation, but the mechanism has not been explained. METHODS: Nine 30-35-kg domestic pigs underwent carbon dioxide insufflation at 1.5 l/min. Intracranial pressure (ICP), lumbar spinal pressure (LP), central venous pressure (CVP), inferior vena cava pressure (IVCP), heart rate, systemic arterial blood pressure, pulmonary arterial pressure, cardiac output, heart rate, respiratory rate, temperature, and end-tidal CO2 were continuously measured. Mechanical ventilation was used to maintain a constant pCO2. Measurements were recorded at 0, 5, 10, and 15 mmHg of abdominal pressure with animals in supine, Trendelenburg (T), and reverse Trendelenburg (RT) positions. Prior to recording measurements, the animals were allowed to stabilize for 40 min after each increase in abdominal pressure and for 20 min after each position change. RESULTS: The animals showed a significant increase in ICP (mmHg) with each 5-mmHg increase in abdominal pressure (0 mmHg: 14 +/- 1.7; 5 mmHg: 19.8 +/- 2.3, p < 0.001; 10 mmHg: 24.8 +/- 2.5, p < 0.001; 15 mmHg: 29.8 +/- 4.7, p < 0.01). The ICP at 15 mmHg abdominal pressure increased further in the T position (39 +/- 4, p < 0.01). Insufflating in the RT position did not significantly reduce the increase in ICP. The IVCP (mmHg) increased with increased abdominal pressure (0 mmHg: 11.5 +/- 6.2, 15 mmHg: 22.1 +/- 3.5, p < 0.01). This increase correlated with the increase in ICP and LP (r of mean pressures >/=0.95). There was no significant change in CVP. CONCLUSIONS: This study suggests that care may be needed with laparoscopy in patients at risk for increased ICP due to head injury or a space occupying lesion. The mechanism of increased ICP associated with insufflation is most likely impaired venous drainage of the lumbar venous plexus at increased intraabdominal pressure. Further studies of cerebral spinal fluid movement during insufflation are currently underway to confirm this hypothesis.

Animals↗
PubMed1997

Laparoscopic versus open Nissen fundoplication: outcome of surgery in monozygotic twins.

Differences in outcome and cost of laparoscopic and open surgery are continuously being evaluated. Two-year-old monozygotic twin boys with a previous history of prematurity, severe gastroesophageal reflux disease, and intractable reactive airway disease were each scheduled to undergo a laparoscopic Nissen fundoplication (LNF) on the same day. Current medications for both patients included albuterol, cromolyn sodium, dexamethasone, ranitidine, and metoclopramide. In the first case, the laparoscopic procedure was converted to an open Nissen fundoplication (ONF) to gain expeditious control of bleeding from a short gastric vessel close to the spleen. The second patient underwent LNF without complication. Operative time for each patient was 3.5 h. The postoperative length of stay for each patient was 6 days (ONF) and 4 days (LNF). The total hospital charges were $21,931 (ONF) and $19,108 (LNF). The first patient (ONF) was readmitted later on the day of discharge (postoperative day 6) for vomiting and was discharged after 24 h with no further treatment. The subsequent course of each patient was similar. At a 6-week follow-up visit, both patients were tolerating a regular diet with weight gain and dramatic improvement in pulmonary symptoms.

Child, Preschool↗
PubMed1996

Controlled trial of laparoscopic-assisted vs open colon resection in a porcine model.

BACKGROUND: Several series of laparoscopic colon resection have been reported in the literature with varied results; however, no controlled series of laparoscopic vs open colon resection has been reported. The purpose of this study was to determine the relative safety and adequacy of laparoscopic colon resection in a controlled trial using a porcine model. METHODS: Domestic pigs (n = 23) were randomly divided into two groups. Animals underwent either an open or laparoscopic-assisted segmental resection of the sigmoid colon. The open resections were performed through a 20-cm midline incision and the laparoscopic technique utilized five 12-mm ports. Laparoscopic resection took twice as long to complete as open resection (P < 0.001). Return of gastric function was significantly faster in the laparoscopic group than in the open group (P < 0.032). RESULTS: No significant differences were found in total length of resection, proximal or distal margins, number of lymph nodes recovered, length of mesenteric vessel resected, or time to return of bowel function. At vivisection, more adhesions to the abdominal wall were noted in the open group (P < 0.002). One death occurred in the laparoscopic group 2 h postoperatively (8.3% mortality) while all open group pigs survived. However, there was no statistically significant difference in mortality rates by chi-square analysis (P > 0.5). CONCLUSIONS: Despite longer operative time, laparoscopic intervention is technically feasible, safe, and may offer significant postoperative benefits due to fewer abdominal adhesions.

Anastomosis, Surgical↗
PubMed1994

Is immune function better preserved after laparoscopic versus open colon resection?

The purpose of this preliminary study was to evaluate immunologic responses to laparoscopic vs standard open colon resection and to evaluate possible mediators of any differences found. Specifically, we compared cortisol levels and delayed-type hypersensitivity response after each method of colon resection in a group of 20 pigs. Two groups of 10 animals each were treated in identical fashion including bowel preparation, anesthesia, and postoperative management. The only difference between groups was that one underwent laparoscopic and the other an open colon resection. Blood specimens for cortisol were drawn before, during, and immediately postoperatively as well as at 11 A.M. on postoperative days 1 and 2. All animals had been previously immunized as piglets with Sow Bac-E (Oxford Veterinary, Worthington, MN), an antigen preparation of common pig pathogens. At the conclusion of the operative procedure 0.5 cc of the antigen was injected intradermally on the right forelimb of the animals. At 48 and 72 h postoperatively the largest diameters of induration surrounding the injection site were measured and averaged. Cortisol levels were measured in serum samples by radioimmunoassay (Met-Path, Rockville, MD). Statistical significance was determined by t-test. Results of skin antigen testing showed that the group of pigs that underwent laparoscopic resection had a 20% greater response, 1.54 cm +/- 0.28 cm at 48 h and 1.53 cm +/- 0.18 cm at 72 h. For the open-surgery group results were 1.24 cm +/- 0.26 cm at 48 h and 1.32 cm +/- 0.21 cm at 72 h, P < 0.05 for the difference between groups at both 48 and 72 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗