Biomedical subjects
Publications and source records attributed to Stephen R Hazelrigg.
Endobronchial valves have recently emerged as a possible alternative to lung volume reduction surgery to treat incapacitating emphysema. The early experience with placement of these valves has been shown to be safe, with short-term improvements of quality of life in this patient population. We report a case in which these valves were used to treat a patient with a persistent air leak.
Numerous factors increase the risk for GI complications in patients undergoing lung resection. It seems that the more debilitated the patient and the more extensive the COPD, the higher the risk. The most commonly reported cause of mortality after lung surgery is multi-organ failure accompanying respiratory failure. The trigger site for multi-system failure is often the GI system. Some risk factors cannot be altered, such as diabetes and the cardiovascular effects of long-term smoking. Other factors, such as steroid dose, anemia, hypoxia, narcotics, and other medications, can be modified. In addition, a high suspicion and early recognition of GI problems in the postoperative period can decrease their mortality. Severe GI complications after lung resection may be frustrating and poorly tolerated in high-risk patients, with little margin for error. Heightened awareness along with early recognition can prevent these complications and alter their outcome.
BACKGROUND: Atrial fibrillation after coronary artery bypass is reported from 17% to 53%. Hypomagnesemia after this surgery is considered a contributing factor. METHODS: Two hundred-two coronary bypass patients were randomized to magnesium (n = 105) or placebo (n = 97). The experimental group received 80-mg magnesium sulfate per kilogram ideal weight in 100 mL dextrose 5% water 30 minutes preoperatively. Postoperatively, patients received 8-mg magnesium sulfate per kilogram ideal weight intravenous per hour more than 48 hours. The control group received dextrose 5% water at these intervals. RESULTS: After the first bolus serum magnesium was experimental 4.75 mg/dL versus control 1.91 mg/dL, p less than 0.001, and remained different until postoperative day 4 (experimental 2.33 mg/dL vs control 2.26 mg/dL, p = 0.24). Atrial appendage and strap muscle were analyzed after the first bolus and after revascularization. There were no differences between groups in tissue magnesium or calcium. Urinary magnesium was elevated in the experimental (experimental 324.5 mg/24 hours, vs control 45.1 mg/24 hours, p = 0.01). Calcium excretion was higher (experimental 370 mg/24 hours vs control 186 mg/24 hours, p < 0.001) and was associated with lower serum calcium. Serum calcium was higher in the control through the fourth postoperative day. The incidence of atrial fibrillation was experimental 32 of 105 (30.5%) versus control 41 of 97 (42.3%) p = 0.08. Atrial fibrillation was different on the first postoperative day (experimental 3/105, 2.9% vs control 9/97, 9.3%), p = 0.05. CONCLUSIONS: Overall prophylactic magnesium supplementation does not significantly reduce atrial and ventricular arrhythmias. The only significant benefit of magnesium supplementation was on the first postoperative day.
Pulmonary function is affected by several variables. The more marginal the patient, the more important the preoperative and perioperative assessment becomes. VATS might be tolerated well with regard to pulmonary function in the early postoperative period. It has allowed thoracic surgeons to expand surgical indications to patients that previously would not have been considered.
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The history of surgery for emphysema is filled with numerous surgical attempts to improve the disorder. Although many of these procedures have proved to be futile, lung volume reduction surgery has now arrived. This article outlines the progression of procedures and the logic for which they were thought to be of benefit.
Many individuals with cardiovascular diseases undergo periodic physical conditioning with or without medication. Therefore, this study investigated the interaction of exercise training and chronic nitroglycerin treatment on blood pressure (BP) and alterations in nitric oxide (NO), glutathione (GSH), antioxidant enzyme activities and lipid peroxidation in rats. Fisher 344 rats were divided into four groups: (1) sedentary control, (2) exercise training for 8 weeks, (3) nitroglycerin (15 mg/kg, s.c. for 8 weeks) and (4) training + nitroglycerin for 8 weeks. BP, heart rate (HR) and respiratory exchange ratio (RER) were monitored weekly for 8 weeks using tail-cuff method and oxygen/carbon dioxide analyzer, respectively. The animals were sacrificed 24 h after last treatments and plasma isolated and analyzed using HPLC, ELISA and UV-VIS spectrophotometric techniques. The results show that exercise conditioning significantly enhanced NO production (p < 0.001), GSH levels (p < 0.001), GSH/GSSG ratio (p < 0.05) and the up-regulation of the activities of catalase (CAT) (p < 0.05), glutathione peroxidase (GSH-Px) (p < 0.001), and glutathione reductase (GR) (p < 0.05), and depression of lactate levels (p < 0.001) in the plasma of the rat. These biochemical changes were accompanied by a significant increase in RER (p < 0.001) without a significant change in BP and HR. Chronic nitroglycerin administration significantly increased NO levels (p < 0.05), GSH levels (p < 0.001), superoxide dismutase (SOD) activity (p < 0.05), GST activity (p < 0.05), and decreased MDA levels (p < 0.05). These biochemical changes were accompanied by a significant decrease in BP (p < 0.05) and without any significant changes in HR and RER. Interaction of exercise training and chronic nitroglycerin treatment resulted in normalization of plasma NO, MDA, lactate levels, and CAT activity. The combination of exercise and nitroglycerin significantly enhanced GSH levels (p < 0.05), and the up-regulation of SOD (p < 0.001), GSH-Px (p < 0.05), GR (p < 0.05) and GST (p < 0.001) activities. These biochemical changes were accompanied by normalization of BP and a significant increased in RER (p < 0.001). The data suggest that the interaction of physical training and chronic nitroglycerin treatment resulted in the maintenance of BP and the up-regulation of plasma antioxidant enzyme activities and GSH levels in the rat.
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Many individuals with cardiac diseases undergo periodic physical conditioning with or without medication. Therefore, this study investigated the interaction of physical training and chronic nitric oxide synthase (NOS) inhibitor (nitro-L-arginine methyl ester, L-NAME) treatment on blood pressure (BP), heart rate (HR) and cardiac oxidant/antioxidant systems in rats. Fisher 344 rats were divided into four groups and treated as follows: (1) sedentary control (SC), (2) exercise training (ET) for 8 weeks, (3) L-NAME (10 mg/kg, s.c. for 8 weeks) and (4) ET+L-NAME. BP and HR were monitored with tail-cuff method. The animals were sacrificed 24 h after last treatments and hearts were isolated and analyzed. Physical conditioning significantly increased respiratory exchange ratio (RER), cardiac nitric oxide (NO) levels, NOS activity and endothelial (eNOS) and inducible (iNOS) protein expression. Training significantly enhanced cardiac glutathione (GSH) levels, GSH/GSSG ratio and up-regulation of cardiac copper/zinc-superoxide dismutase (CuZn-SOD), manganese (Mn)-SOD, catalase (CAT), glutathione peroxidase (GSH-Px) activity and protein expression. Training also caused depletion of cardiac malondialdehyde (MDA) and protein carbonyls. Chronic L-NAME administration resulted in depletion of cardiac NO level, NOS activity, eNOS, nNOS and iNOS protein expression, GSH/GSSG ratio and down-regulation of cardiac CuZn-SOD, Mn-SOD, CAT, GSH-PX, glutathione-S-transferase (GST) activity and protein expression. Chronic L-NAME administration enhanced cardiac xanthine oxidase (XO) activity, MDA levels and protein carbonyls. These biochemical changes were accompanied by increases in BP and HR after L-NAME administration. Interaction of training and NOS inhibitor treatment resulted in normalization of BP, HR and up-regulation of cardiac antioxidant defense system. The data suggest that physical conditioning attenuated the oxidative injury caused by chronic NOS inhibition by up-regulating the cardiac antioxidant defense system and lowering the BP and HR in rats.
BACKGROUND: This is the first clinical report on the feasibility study of two new devices (monopolar Floating Ball and bipolar Sealing Forceps; TissueLink Medical Inc, Dover NH) that incorporated the novel technology of saline enhanced thermal sealing. METHODS: From December 2000 to December 2001, 25 patients (mean age, 54.8 years) with peripheral lung nodules planned for either diagnostic or therapeutic wedge resection were recruited for the study. When the nodule lay deep to a flat lung surface, video-assisted thoracic surgical resection using the modified Perelman technique with the Floating Ball (TissueLink Medical Inc) was preferred. In other patients, the Sealing Forceps (TissueLink Medical Inc) were used for video-assisted thoracic surgical wedge resection. RESULTS: There were no mortality or major intraoperative complications. The Floating Ball was used exclusively in 11 patients; the Sealing Forceps were used in 9 patients; and a combination of the two devices was used in 5 patients. The mean operation time was 70.3 minutes. Average chest drain duration was 3.9 days, and postoperative hospital stay was 5.2 days. There were 2 patients with persistent air leak more than 1 week, one who resolved spontaneously, and the other who required reoperation for control. One patient had pulmonary embolism after a technically uneventful procedure. There have been no late complications after an average follow-up of 10 months. CONCLUSIONS: The devices appear to be technically safe. The Floating Ball has definite advantages over the conventional diathermy and can be adapted to the Perelman procedure using the video-assisted thoracic surgical approach. The Sealing Forceps hold promise to reduce overall consumable costs compared with conventional staplers. These devices should complement the surgeon's existing armamentarium. Comparative studies with conventional instruments are warranted to further define the role of these new devices in thoracic operations.
Pain is one of the most important considerations in the care of thoracic surgical patients. Failure in pain management is associated with increased mortality and morbidity. Acute pain management aspires to stop the painful stimuli before it is transferred to the CNS. The authors recommend (1) a thorough explanation of the operation and the expected outcome to the patient, (2) preoperative pulmonary rehabilitation for those with marginal lung function, (3) choosing the least painful surgical approach with acceptable exposure, (4) minimizing tissue trauma during surgery, (5) preemptive analgesia, and (6) early ambulation as prophylactic measures that should be employed during hospitalization. Good acute pain control should reduce the incidence of chronic pain. Mediansternotomy and VATS seem to be less acutely painful approaches than thoracotomy for most thoracic surgery. One should rule out recurrent malignancy as the etiology for chronic or recurrent pain. Opioids and NSAIDs are sufficient to produce optimal pain control in patients who undergo VATS and sternotomv. TEA is typically reserved for patients who have a thoracotomy. Opioid PCA can be used instead of-or after the discontinuation of-the epidural catheter. Chronic pain can be treated in many ways, and input from a pain clinic might be beneficial. The single best approach to chronic pain is to prevent it. This can be achieved by selecting the right incisional approach, instituting early physical therapy, and achieving optimal postoperative pain control.
Abstract: Carboplatin, a second-generation platinum-containing anticancer drug, is currently being used against a variety of cancers. High-dose carboplatin chemotherapy can cause renal tubular injury in cancer patients. However, the biochemical mechanism of carboplatin-induced renal injury has not been well studied. This study investigated the dose response of carboplatin-induced changes in endogenous antioxidants, lipid peroxidation and platinum content in rat kidney. Male Wistar rats (250-300 g) were divided into five groups and treated as follows: (1) control (saline, intraperitoneally); (2) carboplatin (64 mg/kg, intraperitoneally); (3) carboplatin (128 mg/kg, intraperitoneally); (4) carboplatin (192 mg/kg, intraperitoneally); and (5) carboplatin (256 mg/kg, intraperitoneally). The animals were sacrificed four days after treatment. The blood and kidneys were isolated and analyzed. Plasma creatinine and blood urea nitrogen levels were increased significantly in response to carboplatin in a dose-dependent manner. Renal superoxide dismutase and catalase activities were decreased significantly due to carboplatin at dosages of 128 mg/kg and above. The protein expressions of renal copper/zinc-superoxide dismutase and manganese-superoxide dismutase significantly depleted after carboplatin. Carboplatin (192 and 256 mg/kg) significantly increased lipid peroxidation (malondialdehyde concentration) in rat kidneys. Carboplatin dose-dependently increased the renal platinum concentration, with significance at dosages of 128 mg/kg and above. Carboplatin (256 mg/kg) significantly increased renal xanthine oxidase activity, while ratio of reduced to oxidized glutathione depleted significantly. The data suggested that carboplatin caused dose-dependent oxidative renal injury, as evidenced by renal antioxidant depletion, enhanced lipid peroxidation, platinum content, plasma creatinine and blood urea nitrogen levels in rats.
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