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Biomedical subjects

J B Mark

Publications and source records attributed to J B Mark.

At least 55 records · Page 3Linked to original sources
PubMed1992

Electrocardiographic R-wave changes during cardiac surgery.

The diagnostic accuracy of exercise electrocardiography has been improved by incorporation of R-wave gain factor to correct the measured ST-segment changes. If marked changes in R-wave amplitude occur in individual patients during cardiac operations, a similar gain factor correction may improve the intraoperative diagnosis of myocardial ischemia. This investigation was designed to determine the frequency and magnitude of intraoperative V5 R-wave amplitude changes during cardiac operations. Electrocardiograms were recorded from 83 patients while patients were awake, anesthetized (baseline), after placement of the Favaloro and Canadian sternal retractors, and at end-operation. Compared with baseline values, placement of the Canadian sternal retractor was associated with a reduction in V5 R-wave amplitude from 15 +/- 1 to 10 +/- 1 mm (mean +/- SEM), in V5 S-wave amplitude from 3.5 +/- 0.4 to 1.7 +/- 0.3 mm, and in absolute ST-segment deviation from 0.50 +/- 0.04 to 0.39 +/- 0.05 mm. Changes in V5 R-wave amplitude were correlated with changes in ST-segment deviation in patients with baseline ST-segment deviations greater than or equal to 0.5 mm (r = 0.55, P = 0.0004, n = 37). Changes associated with the Favaloro retractor and the respiratory cycle were less marked. However, the V5 R-wave amplitude was decreased from 15 +/- 1 to 9 +/- 1 mm at end-operation. In conclusion, sternal spreading with the Canadian retractor was associated with marked reductions in V5 R- and S-wave amplitudes and ST-segment deviations. Marked changes in V5 R-wave amplitude persisted after sternal closure.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1991

Central venous pressure monitoring: clinical insights beyond the numbers.

CVP monitoring as a safe, cost-effective alternative to PA monitoring continues to have strong advocates. Recent reports suggest that outcome following major aortic reconstructive and cardiac surgery may be equivalent with either CVP or PA monitoring, thus encouraging use of the simpler, cheaper, and safer alternative. As observant clinicians give CVP monitoring renewed attention, a wealth of useful circulatory information becomes available, which has been obscured by the failure to look beyond the numbers.

Central Venous Pressure↗
PubMed1991

Continuous arterial and venous blood gas monitoring during cardiopulmonary bypass.

A new monitoring technique, based on optical fluorescence chemistry, allows continuous monitoring of all blood gas variables during cardiopulmonary bypass. To evaluate the clinical performance of this monitor, we drew 220 arterial and 216 venous blood samples from 15 patients, and simultaneous blood gas values displayed by the monitor were compared with standard laboratory measurements. The continuous monitor predicted laboratory values with varying degrees of accuracy. (R2 values by linear regression: arterial oxygen tension 0.86, venous oxygen tension 0.36, arterial carbon dioxide tension 0.58, venous carbon dioxide tension 0.72, arterial pH 0.53, venous pH 0.58; pH 0.53, venous pH 0.58; p less than 0.0001). Monitor values of arterial oxygen tension overestimated laboratory values (bias = + 43.5 mm Hg), but the laboratory reference method likely underestimated true arterial oxygen tension in the high range achieved on bypass. Monitoring of venous oxygen tension was imprecise (precision = +/- 6.51 mmHg), regardless of whether stable conditions existed during the sampling period. Monitoring of carbon dioxide tension and pH showed small bias (carbon dioxide tension within 2 mm Hg, pH within 0.03) and good precision (carbon dioxide tension within 3 mm Hg, pH within 0.03). With the development of unstable conditions on bypass, monitor arterial oxygen tension values showed a changing relationship to corresponding laboratory values. In conclusion, arterial and venous carbon dioxide tension and pH monitoring provide acceptably accurate alternatives to laboratory measurement of these variables during cardiopulmonary bypass. Arterial oxygen tension monitoring accurately indicates changes in oxygen tension in the arterial oxygen tension range typically produced during extracorporeal circulation. Oxygen tension monitoring in the venous oxygen tension range is too imprecise for clinical decision-making purposes.

Aged↗
PubMed1990

Selection factors resulting in improved survival after surgical resection of tumors metastatic to the lungs.

From 1973 through 1987, a total of 140 patients underwent 184 operations for removal of metastatic tumors to the lungs. The number of lesions removed ranged form one to 30. Of the patients, 44% had solitary lesions. Overall 3-year survival was 62.6%, and 5-year survival was 48.2%. In all primary tumors except melanoma and breast cancer, 3-year survival was greater than 50% and 5-year survival was greater than 40%. With rare exceptions, the operation of choice for unilateral lesions was ipsilateral thoracotomy, and for bilateral lesions it was median sternotomy. Adequate conservative resection was the rule. There were three pneumonectomies, 25 lobectomies, 71 single wedge resections, 38 multiple unilateral wedge resections, and 47 bilateral wedge resections. There were no postoperative hospital deaths. Cox covariate analysis demonstrated improved survival in patients whose largest lesion was less than 1.5 cm in diameter and with disease-free interval longer than 1 year, but survival was not related to number of lesions or age of patient. An aggressive surgical approach is justified in patients with most primary tumors and a limited number of lung metastases less than 1.5 cm in diameter. Resection of metastases from melanoma and breast cancer should be accomplished after other sites of metastatic disease have been ruled out by the most stringent criteria.

Adolescent↗
PubMed1990

Management of anterior mediastinal tumors.

The most common neoplasms of the anterior mediastinum are thymomas, lymphomas, and germ cell tumors. Surgical exploration was the routine approach to the diagnosis and management of these tumors. This is no longer true. The appropriate initial treatment of these neoplasms varies from surgical resection to radiation therapy to systemic chemotherapy. Except for the small well-encapsulated anterior mediastinal mass, it is imperative that a definitive tissue diagnosis be obtained before initiating treatment. An overview of these tumors and the specific approaches to their treatment are detailed.

Humans↗
PubMed1990

Continuous epidural hydromorphone for postthoracotomy pain relief.

Forty-four patients were treated with a continuous infusion of lumbar epidural hydromorphone (0.05%) after thoracic operations. Postoperatively, visual analog pain scores were obtained. On postoperative day 1 and 2, more than 90% of the patients experienced either no pain (visual analog pain scale = 0) or mild pain (visual analog pain score = 1 to 3) at rest. The incidence of side effects (hypoventilation, pruritus, and nausea) was less than reported with other epidurally administered opioids. Continuous infusion of lumbar epidural hydromorphone produced safe, predictable analgesia after thoracotomy.

Analgesia, Epidural↗
PubMed1988

How far should we go?

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed1988

A new catheter system with remote tip guidance for endobronchial brachytherapy.

Endobronchial brachytherapy is being used with increased frequency in the treatment of recurrent neoplastic obstruction of the major airways, alone or in combination with Nd-YAG laser ablation of the occluding tumor mass. Currently available catheter systems are not reliable with respect to accurate and simple bronchoscopic guidance during placement. Flexibility, wall strength and radiation transmission characteristics are not optimized. We describe a system that meets these goals which has been designed and tested in our department. It is composed of an external handle, deflecting guidewire, and catheter specially modified for endobronchial brachytherapy, with a tip that can be maneuvered in any direction with one hand from outside the patient. Major advantages of the system are ease of concurrent bronchoscopy and catheter guidance, good dosimetric characteristics of the catheter, reasonable cost, and ready availability for adaptation to various techniques of endobronchial brachytherapy.

Brachytherapy↗
PubMed1987

Anesthetic induction with fentanyl and intravenous lidocaine for coronary artery surgery.

In a randomized, double-blind trial, 59 patients undergoing coronary artery surgery received fentanyl 10, 15, or 25 microg/kg infused over 5 minutes for anesthetic induction. Half of the patients received intravenous lidocaine, 1.5 mg/kg, 1 minute before laryngoscopy. Efficacy of induction as judged by loss of consciousness was evaluated, and hemodynamic values during induction, laryngoscopy, and tracheal intubation were recorded each minute for 10 minutes. Plasma fentanyl concentrations were determined after termination of the fentanyl infusion. Opioid induction with fentanyl was successful in 90% (18 of 20) of patients receiving 25 microg/kg, 89% (17 of 19) of patients receiving 15 microg/kg, but only 55% (11 of 20) of patients receiving 10 microg/kg (P < .01). While plasma fentanyl concentrations were proportional to the dose infused (25 ng/mL, 18 ng/mL, and 14 ng/mL in the 25, 15. and 10 microg/kg fentanyl groups, respectively), there was no relationship between plasma fentanyl concentration and hemodynamic response to laryngoscopy or intubation. Opioid induction caused a gradual decrease in blood pressure that was restored with intubation. Lidocaine partially blocked this restoration (systolic blood pressure 122 +/- 5 v 138 +/- 5 mmHg, lidocaine v placebo, 1 minute after laryngoscopy, P < .05). Fentanyl, 15 or 25 microg/kg, intravenously, is an effective induction agent for patients with coronary artery disease. Supplementation with intravenous lidocaine, 1.5 mg/kg, will obtund the increase in blood pressure that occurs with laryngoscopy and intubation and help prevent infrequent hypertensive responses seen with this opioid technique.

Adjuvants, Anesthesia↗