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Biomedical subjects

D T Martin

Publications and source records attributed to D T Martin.

At least 55 records · Page 3Linked to original sources
PubMed1995

Laparoscopic antegrade sphincterotomy. A new technique for the management of complex choledocholithiasis.

OBJECTIVE: Laparoscopic antegrade sphincterotomy represents a new technique that expands the ability of the surgeon to manage complex choledocholithiasis at the time of laparoscopic cholecystectomy. The authors describe their experience with six patients with cholelithiasis and complex common bile duct stone disease who underwent successful laparoscopic cholecystectomy and antegrade sphincterotomies. SUMMARY BACKGROUND DATA: Patients with complex choledocholithiasis have represented a technical challenge to the minimally invasive surgeon. Recently, a laparoscopic technique of antegrade biliary sphincterotomy has been reported by DePaulo in Brazil. This technique has been successful at clearing the common bile duct at the time of laparoscopic cholecystectomy. METHODS: Laparoscopic antegrade sphincterotomy was performed in six patients with multiple common bile duct stones. A standard endoscopic sphincterotome was introduced antegrade via the cystic duct or common bile duct and guided through the ampulla. A side-viewing duodenoscope was used to confirm proper positioning of the sphincterotome. Then a blended current was applied until the sphincterotomy was complete. RESULTS: There was no mortality or morbidity associated with laparoscopic antegrade sphincterotomy. The mean additional operative time to complete laparoscopic antegrade sphincterotomy was 19 minutes. Three of the six patients were noted to have transient, asymptomatic elevation in serum amylase levels immediately after surgery (average 252 international units/L; normal < 115), which normalized within 72 hours. The mean postoperative hospital stay was 2.9 days. At a mean follow-up of 5 months (range 1 to 10 months), five patients remain asymptomatic. One individual with acquired immune deficiency syndrome had persistent symptoms, and a diagnosis of cytomegalovirus pancreatitis was eventually made. CONCLUSIONS: Laparoscopic antegrade sphincterotomy appears to be a safe and effective technique for the management of complex biliary tract disease.

Adult↗
PubMed1995

Transvenous cardioverter defibrillators: cost implications of a less invasive approach.

To assess the economic impact of a transvenous lead system for an implantable cardioverter defibrillator (ICD), we evaluated the hospital charges for two groups of patients: group I patients (n = 23) underwent implantation of an ICD generator with an epicardial lead system via a thoracotomy and group II patients (n = 25) underwent implantation of the same generator using transvenous leads. There was no difference in demographics between the two groups. There was a 15% decrease in total charges for the transvenous group compared to the thoracotomy group ($54,142 vs $63,359, P < 0.05). Evaluation of the component charges revealed that the decline could be attributed to a reduction in implant ($27,328 vs $29,285, P < 0.02) and convalescent charges ($7,703 vs $15,179, P < 0.01) for the transvenous group. There was a corresponding decrease in length of stay for the transvenous group (22 vs 29 days, P < 0.05) largely secondary to a 38% reduction in convalescent length of stay (8 vs 13 days, P < 0.05). We conclude that the use of transvenous lead systems for the ICD results in a significant reduction in hospital charges as well as hospital length of stay.

Aged↗
PubMed1994

Laparoscopic-assisted colon resection.

The popularity and success of laparoscopic biliary tract surgery have persuaded surgeons to explore other applications for rigid endoscopic surgery. From July 1990 to February 1993 a total of 65 patients (mean age 57 years; range 41-82) underwent attempted laparoscopic colon resection. Indications for surgical intervention included cancer (39), adenomatous polyps (14), diverticulosis (10), stricture (1), and foreign-body perforation (1). A laparoscopic-assisted technique whereby the specimen was removed and the anastomosis was completed outside of the abdomen was used in all patients. A dilated umbilical opening was used for right-sided lesions and a left-lower-quadrant muscle-splitting incision for descending and sigmoid colon resections. Two patients required conversion to open laparotomy. There were no deaths and only four complications (pneumonia 1, urinary tract infection 1, prolonged ileus 1, and subfascial abscess 1). The mean postoperative stay was 4.4 days (range 3-8 days) and the average interval for return to normal activity was 8 days. Laparoscopic-assisted colon resection appears to be a safe and beneficial option for many patients with pathologic disorders of the large intestine. Future clinical trials are needed to fully determine the appropriateness of this procedure in patients with localized malignancies.

Adult↗
PubMed1994

Successful management of severe gastroesophageal reflux disease with laparoscopic Nissen fundoplication.

BACKGROUND: Nissen fundoplication has been shown to be superior to medical treatment in the management of severe or complicated gastroesophageal reflux disease (GERD). Rapid advances in minimally invasive surgical technique and recognition of the advantages of reduced incision-related morbidity have fostered application of laparoscopic techniques to antireflux surgery. A prospective evaluation of 70 patients undergoing laparoscopic Nissen fundoplication for severe GERD was undertaken. PATIENTS AND METHODS: Rigid selection criteria for laparoscopic Nissen fundoplication included severe or refractory disease with documentation of abnormal esophageal acid exposure by 24-hour pH probe monitoring, documentation of a mechanically defective lower esophageal sphincter by esophageal manometry, and absence of severe esophageal and/or gastric motility disorders. RESULTS: Sixty-eight of 70 patients were completed laparoscopically with an intraoperative morbidity rate of 9%. Major postoperative complications occurred in 3 patients (4%) and included deep venous thrombosis (n = 1), delayed gastric leak (n = 1), and trocar site hernia (n = 1). The average hospital stay was 3.0 days, and the average time to return to normal activity was 7.0 days. All patients experienced relief of symptoms of reflux with mean follow-up of 7.7 months. Transient, mild dysphagia was experienced by 37% of patients, and persistent, severe dysphagia by 7%. The mean increase in lower esophageal sphincter pressure was 16.2 mm Hg. The total and intra-abdominal sphincter lengths increased an average of 1.5 and 1.4 cm, respectively. CONCLUSIONS: These preliminary data suggest that laparoscopic Nissen fundoplication can be performed by experienced laparoscopic surgeons with excellent symptomatic and physiologic results and a morbidity rate comparable to conventional open antireflux procedures. Rigid patient selection criteria will help identify the patients most likely to benefit from reconstruction of a mechanically defective lower esophageal sphincter. Adherence to established operative principles for Nissen fundoplication will reduce the incidence of significant postfundoplication symptoms.

Adult↗
PubMed1994

Effects of interval training and a taper on cycling performance and isokinetic leg strength.

The purpose of this study was to determine whether changes in isokinetic leg strength parallel changes in cycling performance during a six-week high-intensity aerobic interval training program and a subsequent two-week taper. Eleven male collegiate cyclists participated in one competitive cycling graded exercise test, four consecutive days of aerobic intervals (30 min @82.2 +/- 0.74% HRmax, 1:1 work:relief), and four continuous rides (1-2 hr @65-80% HRmax) weekly. Pedalling cadence during training was generally 70-80 rpm suggesting a knee joint velocity of approximately 210 degrees.sec-1. Cycling performance and peak isokinetic torque (TQpk) for knee flexors (HAM) and knee extensors (QUAD) @30, 120, 210, and 300 degrees.sec-1 were assessed before, every two weeks during, and each week for two weeks following six weeks of interval training. Performance increased significantly during training (15%) and increased further during the taper (8%). QUAD TQpk @30 and 120 degrees.sec-1 increased significantly during training and the taper. In contrast, QUAD TQpk @210 and 300 degrees.sec-1 and HAM TQpk for all velocities were not significantly elevated following training. Interestingly, QUAD TQpk @300 but not 210 degrees.sec-1 significantly increased during the taper. Data from this study demonstrates that high-intensity aerobic interval cycling can promote gains in QUAD strength which occur primarily at contraction velocities slower than those utilized during cycling training. Additionally, a two-week taper can produce significant improvements in cycling performance (8%) and QUAD strength (8-9%) at 30 and 120 degrees.sec-1, however, the time-courses for these improvements do not parallel one another.

Adaptation, Physiological↗
PubMed1994

Advances in ICD lead systems.

We have presented both technical and clinical data indicating that transvenous lead systems are comparable to standard epicardial ICD systems with respect to efficacy. In addition there may be a reduction in morbidity when compared with the standard epicardial implant. We have shown for the Endotak and Transvene systems that each has its own idiosyncrasies, advantages, and disadvantages. Other lead systems are too early in their clinical evaluations for such definitive statements to be made. Regarding long-term reliability, the issues of mechanical integrity of the insulation and conductor materials, as well as the stability (or otherwise) of sensing and defibrillating characteristics remains to be determined for all lead systems. Similarly, compatibility between lead systems and pulse generators made by different manufacturers cannot be assumed, but needs to be prospectively examined in rigorous clinical trials.

Defibrillators, Implantable↗
PubMed1994

Rise in chronic defibrillation thresholds in nonthoracotomy implantable defibrillator.

BACKGROUND: To establish the chronic stability of defibrillation thresholds (DFTs) in a transvenous cardioverter/defibrillator (TCD) system, we studied 37 consecutive patients with TCD systems implanted for > 6 months. METHODS AND RESULTS: DFT was measured by a step-down method at implant and 2 and 6 months later. The mean ejection fraction was 34.5 +/- 14.3%. Coronary artery disease with previous myocardial infarction was present in 31 patients. The mean DFT rose from 13.3 +/- 4.3 J at implant to 16.5 +/- 4.7 J at 2 months (P < .001) and 17.6 +/- 5.4 J at 6 months (P < .0001). ANOVA revealed a statistically significant rise in DFT over time (P < .0005). At 2 months, 25 patients had a rise in DFT, and 14 had a rise > or = 5 J. The observed rise at 2 months persisted in 19 patients. A chronic rise, defined as > or = 5 J rise at 6 months, occurred in 17 patients. Univariate analysis of clinical as well as implant variables revealed no predictors of a rise in DFT in this group. CONCLUSIONS: We conclude that there is a significant rise in DFT at 2 and 6 months in this TCD system. Although the chronic threshold remained well within the available energy range of the pulse generator, this observation has important implications for implantation guidelines, programming, and future pulse generator development for TCD patients.

Aged↗
PubMed1994

Appropriate sensing of ventricular fibrillation after failed shocks in a transvenous cardioverter-defibrillator system.

BACKGROUND: Reduction in R-wave amplitude immediately after defibrillation shocks in an integrated shock/sense transvenous cardioverter-defibrillator (TCD) lead system has prompted concerns regarding adequate sensing after failed shocks. We therefore studied redetection characteristics for ventricular fibrillation after unsuccessful defibrillation shocks in a TCD system to determine if these observations have clinical relevance. METHODS AND RESULTS: Fifty patients with this shock/sense TCD lead system underwent conversion testing of their TCD at several time intervals. There were a total of 142 failed shocks events recorded, including 10, 15, 70, and 47 events at implantation, predischarge, and 2- and 6-month testing, respectively. Initial detection time (IDT) and redetection time (RDT) for ventricular fibrillation were measured from event markers for all unsuccessful defibrillation shocks. To assess the effect of failed shocks on electrogram quality, 54 failed shock episodes were evaluated in 37 of the 50 patients by measuring electrograms during VF before and after shock. Mean RDT for the entire group was 5.3 +/- 3.5 seconds compared with an IDT of 4.5 +/- 3.3 seconds (P = NS). There were no significant differences between IDT and RDT at implantation or any follow-up testing period, despite a significant decline in R-wave amplitude from 8.1 +/- 3.5 to 6.8 +/- 2.8 mV (P < .0001) measured 3 to 6 seconds after shock delivery. Analysis of 8 individuals with any extended RDT (> or = 10 seconds) showed no significant differences in clinical or implantation characteristics when compared with 42 individuals without extended RDT. CONCLUSIONS: In this integrated shock/sense TCD lead system, unsuccessful shock delivery has no significant effect on redetection of ventricular fibrillation at device implantation or up to 6 months of follow-up, despite an observed reduction in postshock R-wave amplitude. Therefore, the reported reduction in electrogram quality after a shock is of no practical importance because sensing of ventricular fibrillation does not appear to be compromised in this particular TCD system. Whether this applies to other implantable cardioverter-defibrillator pulse generators and lead systems with different sensing characteristics requires further evaluation.

Aged↗
PubMed1994

Laparoscopic and endoscopic management of common bile duct stones.

The rapid evolution and acceptance of laparoscopic cholecystectomy for the management of symptomatic cholelithiasis and acute and chronic cholecystitis are unprecedented in modern surgical practice. With rapid advances in laparoscopic and endoscopic instrumentation and surgical skills, many surgeons are developing minimally invasive techniques and strategies for treating the patient with known, suspected, or unsuspected choledocholithiasis. Recent articles describing the current status, complications, results, and future directions of laparoscopic and endoscopic management of common bile duct stones are reviewed. The role of endoscopic retrograde cholangiopancreatography and sphincterotomy, laparoscopic exploration of the common bile duct, choledochoscopy, and percutaneous transhepatic extraction techniques are discussed.

Cholecystectomy, Laparoscopic↗
PubMed1993

Anthropometric profiles of elite male and female competitive sport rock climbers.

Over the past few years, competitive rock climbing--for a long time a popular sport in Europe--has increased in popularity in North America. An annual international World Cup competition circuit was started in 1988 which has shown growing success and a definite elite group of athletes has emerged. Descriptive anthropometric profiles of elite climbers have been unavailable. In order to fill this information void, 39 world-class climbers (21 males, 18 females) were assessed immediately prior to competition at an international World Cup sport climbing championship. All of the subjects tested were competition semi-finalists and, among these, seven males and six females advanced to the finals. The variables measured included age, years of climbing experience, height, body mass, height-weight ratio, sum of seven skinfolds, % body fat, fat-free mass, hand and arm volumes via plethysmography, average of right and left grip strengths, grip strength to body mass ratio (SMR), and climbing ability defined as the most difficult route climbed on lead. The results indicated that elite sport climbers are of small to moderate stature and exhibit very low % fat, moderate grip strength and high SMR when compared with other athletic groups. Values for the height-weight ratio and sum of seven skinfolds in the female finalists were very near those of the male finalists, which may indicate that reduction of body mass and % fat are primary adaptations in these female athletes. Climbing ability was predictable from SMR and % fat, though the R2 was low.

Adult↗
PubMed1992

The effect of Alpine mountaineering on acute erythrocyte hemolysis.

The purpose of this study was to determine whether erythrocyte hemolysis occurs during a mountain ascent over snow and ice to 3285 meters. Data were collected from six experienced recreational mountaineers, 2 females and 4 males, who participated in a six-day ice climbing seminar and peak ascent in the North Cascades mountain range of the United States. Blood samples were collected from an antecubital vein at sea level (S1), in a base camp at 1515 m prior to the summit ascent (S2), on the summit at 3285 m after 6.5 hours of climbing (S3), at base camp immediately after the descent (S4), and at sea level following a trail descent from the base camp (S5). Whole blood samples were chilled and analyzed for complete blood count including hemoglobin (Hb) concentration, hematocrit (Hct), and white blood cell count (WBC). Serum was frozen and later analyzed for serum haptoglobin (Hapt). No significant changes were found for Hct and Hb among the samples. Mean (+/- SEM) Hapt values were 125 (+/- 28), 113 (+/- 25), 100 (+/- 18), 103 (+/- 32), and 109 (+/- 23) mg.dl-1 for S1 through S5, respectively. No significant differences were found among the Hapt values. Plasma volume changes (% PVC) were calculated from Hct and Hb. Mean estimated % PVC were -4.16 (+/- 1.55), -2.54 (+/- 3.93), 7.46 (+/- 4.86), and 4.80 (+/- 3.49) percent between S1 and S2, S2 and S3, S3 and S4, and S4 and S5, respectively. Total body haptoglobin (TBH) was estimated from Hapt and % PVC in an attempt to correct for the plasma volume change effect on haptoglobin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Exertional intensities and energy requirements of technical mountaineering at moderate altitude.

The purpose of this study was to determine the exertional energy requirements of technical mountaineering at moderate altitude. Six subjects completed maximum graded exercise tests (MGXT) prior to a 7-day ice climbing seminar conducted in the North Cascade Range of the United States. Mean weight, percent body fat, and maximum oxygen uptake (VO2max) were 71.3 (+/- 15.1) kg, 11.7 (+/- 4.2) %, and 53.7 (+/- 5.4) ml.kg-1.min-1 respectively. Heartrates (HR) were recorded and averaged over 5-second to 1-minute intervals during selected mountaineering activities of the ice climbing seminar. Average and peak estimated VO2 (EstVO2) and estimated energy expenditure (EstEE) were calculated from HR utilizing regression equations generated from the MGXT results. Trail hiking with loads averaging 45% of individual body weight required an average EstVO2 of 21.8 (+/- 3.0) ml.kg-1.min-1 and average EstEE of 7.5 (+/- 1.9) kcal.min-1 over a 2.2 hr period. Mean peak EstVO2 was 37.4 (+/- 3.4) ml.kg-1.min-1 and mean peak EstEE was 13.4 (+/- 3.0) kcal.min-1 during this period. Technical ice climbing involving movement up and down a 12 m vertical height for a mean time of 14.3 (+/- 2.6) min required an average EstVO2 and EstEE of 25.7 (+/- 7.6) ml.kg-1.min-1 and 9.5 (+/- 3.4) kcal.min-1 respectively. Peak EstVO2 and EstEE means were 38.4 (+/- 7.7) ml.kg-1.min-1 and 14.6 (+/- 3.5) kcal.min-1. Two subjects were monitored during a 6-hour summit ascent on snow and ice from 1636 m to 3266 m. Means for average EstVO2 and EstEE were 21.6 (+/- 3.3) ml.kg-1.min-1 and 7.2 (+/- 0.8) kcal.min-1 respectively while peak EstVO2 and EstEE means were 38.0 (+/- 6.1) ml.kg-1.min-1 and 13.3 (+/- 1.6) kcal.min-1. The total EstEE was 3096.8 and 2485.4 kcal for these two subjects over the 6-hour ascent. The most experienced climber averaged 0.078 kcal.kg-1.min-1 and the least experienced subject averaged 0.105 kcal.kg-1.min-1 while climbing at identical paces over the same terrain. This indicates a possible experience factor which may increase climbing efficiency.

Adult↗
PubMed1987

Muscle pathology in the neuroleptic malignant syndrome.

In a fatal case of neuroleptic malignant syndrome, a muscle sample taken within 1 h of death showed acute myopathic features with absence of muscle glycogen and neutral lipid. These features suggest that hyperpyrexia in this syndrome may be caused by heat production from uncoupled phosphorylation in muscle and imply that the primary biochemical abnormality responsible for this uncontrolled heat production might be muscular rather than hypothalamic.

Adult↗
PubMed1986

A critical comparison of the hematologic, cardiovascular, and pulmonary response to steroids and nonsteroidal anti-inflammatory drugs in a model of sepsis and adult respiratory distress syndrome.

Improved survival of patients receiving high-dose steroid therapy in sepsis and adult respiratory distress syndrome (ARDS) has been reported, but such therapy and its benefits remain controversial. Recently research has been directed toward manipulation of the arachidonic acid cascade. Improved survival and hemodynamics with administration of nonsteroidal anti-inflammatory drugs (NSAID) have been reported in animal models of sepsis and ARDS. The purpose of this study was to compare the effects of steroids (methylprednisolone) and NSAID (ibuprofen) in a porcine model of septic ARDS induced by a continuous infusion of live Pseudomonas aeruginosa. Cardiopulmonary parameters were monitored in animals intubated, paralyzed, and ventilated at a 250 ml tidal volume and 0.5 Fio2. Pigs were randomly assigned to one of five groups: groups I and II received respective doses of 12.5 mg/kg ibuprofen and 30 mg/kg methylprednisolone at 20 and 210 minutes after baseline; group III had P. aeruginosa only; groups IV and V received respective doses of ibuprofen and methylprednisolone at 20 and 210 minutes of sepsis. Significant pulmonary edema, increased intrapulmonary shunting, hypoxemia, hemoconcentration, and systemic hypotension occurred with P. aeruginosa infusion. In septic animals treated with ibuprofen normal systemic arterial pressure was maintained, hemoconcentration was decreased, and oxygenation was improved with a significant decrease in shunting and pulmonary edema. Administration of methylprednisolone improved hemoconcentration and cardiac index, but no significant effect on pulmonary edema, intrapulmonary shunting, or oxygenation was observed. The results of this study demonstrated a significant beneficial effect of ibuprofen and we would encourage controlled clinical trials of this drug in the management of sepsis and ARDS. On the other hand, methylprednisolone was found to be relatively ineffective in treatment of circulatory collapse and ARDS associated with sepsis.

Animals↗
PubMed1985

Intraoperative radioimmunodetection of colorectal tumor with a hand-held radiation detector.

A hand-held gamma detection probe was used intraoperatively to localize primary and recurrent colorectal tumors in 28 patients 48 to 72 hours after they received an intravenous injection of 2.2 mCi of iodine-131 labeled anticarcinoembryonic antigen polyclonal baboon antibody. Preoperative evaluation included determination of serum carcinoembryonic antigen, barium enema, colonoscopy, chest film, computerized axial tomography, liver, spleen, and bone scans, and endoscopy when indicated. Preoperative whole-body imaging correctly localized primary tumors in only 33 percent of the patients, whereas it correctly demonstrated tumor in 64 percent of those with recurrent disease. Intraoperative tumor-to-background ratios derived from the detector probe were elevated in all patients, averaging 3.97:1 in primary lesions and 4.18:1 in recurrent tumors. Postoperatively, carcinoembryonic antigen was localized in tissues with the avidin-biotin peroxidase staining technique to confirm intraoperative readings. Variations in stain uptake in a patient could be correlated with variations in radiation detector readings in the same patient. Results support our previous work in nude mice, demonstrating the improved sensitivity and specificity of the hand-held gamma detection device over whole-body imaging for intraoperative localization of immunoradiolabeled tumors.

Animals↗
PubMed1984

Determination of degradation products and impurities of amoxicillin capsules using ternary gradient elution high-performance liquid chromatography.

A specific high-performance liquid chromatography method has been developed for the determination of amoxicillin penicilloic acids (PA), p-hydroxyphenylglycine (p-HPG), 6-aminopenicillanic acid (6-APA) and unidentified materials in amoxicillin capsules. The accuracy of the measurements was demonstrated by the standard addition technique on actual capsule samples. Within-day and between-day precision studies gave coefficients of variation of 3.15 and 1.70% for PA, 4.75 and 3.81% for p-HPG, and 5.59 and 32.23% for 6-APA, respectively. Typical calibration and expanded linearity of response curves for these components show no curvature over the range of interest. The detection limits for PA, p-HPG and 6-APA are 0.7, 0.2 and 0.6 micrograms/ml of sample extract and are considered adequate for the intended use of the method. These levels correspond to 0.35, 0.10, 0.30 mg per 500-mg Amoxil capsule, respectively.

Amoxicillin↗
PubMed1984

A gamma-detecting probe for radioimmune detection of CEA-producing tumors. Successful experimental use and clinical case report.

The detection of tumors with radiolabeled antibodies against CEA is possible; however, current nuclear medicine scanning cameras rarely detect tumors smaller than 2 cm in diameter. One of the limitations to tumor detection is the inability to place a detecting camera near a deeply seated intra-abdominal tumor. A hand-held gamma-detecting probe, suitable for intraoperative use, was designed to locate radioactive tumors. Experimental work with CEA-producing colon tumor xenografts in nude mice suggests this probe is more sensitive than external scanners in detecting small tumors. A case report documents the clinical use of this new intraoperative probe.

Adenocarcinoma↗