Changing systems for measuring activated clotting times: impact on the clinical practice of heparin anticoagulation during cardiac surgery

BACKGROUND: The activated clotting time (ACT) is a standard monitor for heparin anticoagulation during cardiopulmonary bypass (CPB). This study determines the effect of upgrading our ACT system on our clinical practice with regards to the conduct and safety of heparin anticoagulation during cardiopulmonary bypass. METHODS: We compared the intraoperative heparin doses required for all adult cardiac surgery patients (n=1240) and postoperative bleeding for a subset of primary aortocoronary bypass (CABG) surgery procedures (n=285) from cohorts before and after the change in ACT systems. RESULTS: The heparin dose needed to exceed our target ACT of 480 sec for the duration of CPB was higher (45000 vs. 40000 units; p<0.0001), and the mean ACT during CPB was lower (557 vs. 618 sec; p<0.05) using the new ACT system. Furthermore, this coincided with decreased postoperative bleeding in the CABG subset (median value of 417 vs. 575 ml over 12 h; p<0.0005). CONCLUSIONS: We demonstrated that the introduction of the Actalyke ACT system significantly altered our clinical practice by increasing the heparin dose required to exceed our target ACT during CPB. Prospective study to determine the effect of Actalyke ACT system monitoring on hemostasis after cardiac surgery is merited.     

Chronic resistance exercise training improves natural killer cell activity in older women

BACKGROUND: Regular exercise has been reported to slow the age-associated declines in natural killer cell activity (NKCA). To evaluate this response, we recruited older, postmenopausal women (65-85 years old) to fill one of two groups: training (10 weeks of resistance exercise; TR) or control. METHODS: Blood samples were collected from an arm vein in the TR group at rest (PRE), immediately following (POST), and 2 hours (2H) following an acute bout of resistance exercise both before (BEFORE) and after (AFTER) training. Leukocytes and NKCA were determined by flow cytometry and a whole blood (51)Cr release assay, respectively. RESULTS: Acute exercise increased total leukocyte (p < .05), CD8 (p < .05), CD4 (p < .05), and CD56 counts (p < .05), but there was no effect of training. NKCA was greater TR-AFTER-PRE (136%), -POST (80%), and -2H (127%) compared to similar values from TR-BEFORE (p < .05). CONCLUSION: Increased resting NKCA after chronic resistance training suggests that immunity has been improved.     

Improved right ventricular systolic time intervals after digitalis in patients with cor pulmonale and chronic obstructive pulmonary disease

Although digitalis has been used to treat patients with cor pulmonale secondary to chronic obstructive pulmonary disease, its effect on right ventricular performance has not been conclusively determined. This study assessed the effects of acute digitalization on measurement of right ventricular systolic time intervals in patients with chronic obstructive pulmonary disease and cor pulmonale. The intervals were recorded before and 40 minutes after administration of ouabain, 1 mg intravenously, in nine men (mean age 58 ± 5 [standard deviation] years) with chronic obstructive pulmonary disease (mean maximal mid expiratory flow rate 0.29 ± 0.08 1 liters/sec) and electrocardiographic evidence of right ventricular hypertrophy.Ouabain produced significant reductions in right ventricular systolic time intervals, including the right ventricular preelection period (from 117 ± 23 to 102 ± 16 msec; P < 0.01), right ventricular ejection time index (from 397 ± 33 to 375 ± 24 msec; P < 0.01) and mean Q-P₂ index (from 509 ± 23 to 474 ± 8 msec; P < 0.001). In eight patients with simultaneously measured left ventricular systolic time intervals, similar changes were observed, including shortening of the left ventricular preejection period index (from 135 ± 9 to 117 ± 11 msec; P < 0.01), ejection time index (from 395 ± 18 to 379 ± 20 msec; P < 0.01), and the mean Q-A₂ interval (from 530 ± 16 to 495 ± 16 msec; P < 0.001). There were no significant changes in aortic or pulmonary arterial pressures. The results demonstrate that acute administration of digitalis produces significant improvement in right ventricular performance in patients with chronic obstructive pulmonary disease and cor pulmonale. The simultaneous shortening of right and left ventricular systolic time intervals is of comparable magnitude.     

Radiation brain damage induced by interstitial 125I sources: a canine model evaluated by quantitative computed tomography

The canine brain is a good model of the human brain for studying radiation damage after megavoltage x-irradiation for brain tumors. We have further developed this model to study radiation damage induced by high activity interstitial 125I sources. Removable 125I sources were implanted in normal canine brains, and doses of 1,000 to 10,000 rads were delivered to a reference point at a 10-mm radius from the source; dose rates were 35 to 40 rads/hour at the reference point. Serial quantitative analysis of tissue damage (tissue density and contrast enhancement) was done using computed tomographic scanning up to 6 months after implantation and was compared to histopathological findings after the animals were killed. At doses greater than 19,000 rads (i.e., inside the reference point), frank coagulation necrosis was observed. Pronounced vessel-related changes, manifest as areas of contrast enhancement, corresponded to tissues receiving a minimum of 6,000 rads and a maximum of 19,000 rads. These results indicate that this model can be used in serial noninvasive studies to quantify the development of damage induced by interstitial irradiation and to provide dose-response information in individual animals.     

Syphilitic aortic aneurysm presenting with the superior vena cava syndrome

In a 65 year old man with hemoptysis, chest pain, weight loss, clubbing of the digits and a large mediastinal mass, the superior vena cava syndrome developed. He was treated for malignancy with radiation therapy and corticosteroids, but he died shortly after his admission to the hospital. Autopsy revealed syphilitic aortitis with an aneurysm of the ascending aorta compressing the superior vena cava and right mainstem bronchus. The postmortem serology corroborated the morphologic findings of tertiary syphilis. In this report we emphasize the important, although now uncommon, association between the superior vena cava syndrome and aneurysm of the aorta.     

Effects of kainic acid lesions of the striatum on self-stimulation in the substantia nigra and ventral tegmental area

Unilateral kainic acid lesions of the dorsal striatum provided evidence for a dissociation of neural substrates of brain-stimulation reward at sites in the ventral tegmental area and substantia nigra. The lesions caused a significant increase in current intensity thresholds at substantia nigra placements, whereas similar lesions had no effect on self-stimulation thresholds at sites in the ventral tegmentum. In addition, the rate-increasing effects of d-amphetamine (0.1–1.0 mg/kg) on self-stimulation were determined before and after lesions to the dorsal striatum. No significant changes in dose-response curves were observed at either loci. Amphetamine-induced rotation was used to confirm damage to the dorsal striatum and lesioned animals were observed to rotate towards the side of the lesion. In contrast, sham-lesioned animals showed turning away from the side stimulated electrically in previous tests. The results of the self-stimulation and rotation experiments are discussed in the context of neural substrates of reward and motor activity.     

Comparative 60Co total body irradiation (220 cm SAD) and 25 MV total body irradiation (370 cm SAD) dosimetry

Adults with acute leukemia and malignant lymphoma in relapse after conventional therapy are treated with cyclophosphamide and total body irradiation (TBI) followed by autologous bone marrow transplants. For cobalt TBI, patients seated in a stand angled 45° above the floor are treated in a single fraction with sequential right and left lateral 87 cm ×87 cm fields at 220 cm source-axis distance (SAD) using a 5000 Ci cobalt unit. Typical lateral diameters, mid-plane dose rates, mid-plane doses, and maximum doses are: Hips, 34 cm, 8 rad/min, 900 rad, and 1050 rad; and shoulders, 38 cm, 7.7 rad/min, 800 rad, 1080 rad. The estimated lung dose is 1000 to 1100 rad. A compensator limits the dose to the head to 1000 rad. Estimated organ doses are: small intestine, liver and kidneys-1100 rad, and heart-1200 rad. Phantom dosimetry and dosimetry on patients treated reveals that these doses are delivered within 5 % accuracy. Patient tolerance of treatment, and some biological considerations of low dose rate therapy are reviewed. Certain dosimetry features of an alternate treatment at 370 cm SAD, using 25 MV photons are also presented.