Sternal closure with titanium plate fixation--a paradigm shift in preventing mediastinitis

Sternal instability predisposes to post-operative mediastinitis. Biomechanical studies have shown the superiority of rigid plate fixation over wire circlage in sternal healing. We studied rigid plate fixation for sternotomies in high-risk patients. High-risk patients were identified as those having three or more historically established risk factors for post-operative mediastinitis, such as COPD, re-operative surgery, renal failure, diabetes, steroid use, obesity, existing infection, and immunosuppression. Three hundred and twenty high-risk patients had prophylactic rigid plate fixation (Group S) between July 2000 and Jan 2005. The control group (Group C) comprised 215 patients with similar risk profiles that were not plated during 2000 and 2001. Average age, male-female ratio, risk factors and type of procedures were similar in both groups. Follow up ranged from 4 to 200 weeks. There were 12 peri-operative deaths (3.75%) in group S and 8.6% (18 patients) in group C. There were no instances of deep mediastinitis in group S. Group C had mediastinitis in 28 (13%, P<0.05), requiring high dose antibiotics and plastic surgical intervention. Sternal fixation with titanium plates is an effective way of ensuring sternal immobility thereby reducing the substrate for bony infections. Application of this technique in high-risk patients prevents mediastinitis.     

Thermo-wrap technology preserves normothermia better than routine thermal care in patients undergoing off-pump coronary artery bypass and is associated with lower immune response and lesser myocardial damage

OBJECTIVE: Perioperative hypothermia might be detrimental to the patient undergoing off-pump coronary artery bypass surgery. We assessed the efficacy of the Allon thermoregulation system (MTRE Advanced Technologies Ltd, Or-Akiva, Israel) compared with that of routine thermal care in maintaining normothermia during and after off-pump coronary artery bypass surgery. METHODS: Patients undergoing off-pump coronary artery bypass surgery were perioperatively and randomly warmed with the 2 techniques (n = 45 per group). Core temperature, hemodynamics, and troponin I, interleukin 6, interleukin 8, and interleukin 10 blood levels were assessed. RESULTS: The mean temperature of the patients in the Allon thermoregulation system group (AT group) was significantly ( P < .005) higher than that of the patients receiving routine thermal care (the RTC group); less than 40% of the latter reached 36 degrees C compared with 100% of the former. The cardiac index was higher and the systemic vascular resistance was lower ( P < .05) by 16% and 25%, respectively, in the individuals in the AT group compared with in the individuals in the RTC group during the 4 postoperative hours. End-of-surgery interleukin 6 levels and 24-hour postoperative troponin I levels were significantly ( P < .01) lower in the patients in the AT group than in the RTC group. The RTC group's troponin levels closely correlated with their interleukin 6 levels at the end of the operation ( R = 0.51, P = .002). CONCLUSIONS: Unlike routine thermal care, the Allon thermoregulation system maintains core normothermia in more than 80% of patients undergoing off-pump coronary artery bypass surgery. Normothermia is associated with better cardiac and vascular conditions, a lower cardiac injury rate, and a lower inflammatory response. The close correlation between the increased interleukin 6 and troponin I levels in the routine thermal care group indicates a potential deleterious effect of lowered temperature on the patient's outcome.     

Outcome of posttraumatic fibromyalgia: a 3-year follow-up of 78 cases of cervical spine injuries

OBJECTIVE: To assess the outcome of fibromyalgia syndrome (FMS) after cervical spine injury. METHODS: Seventy-eight of 102 (77%) patients with neck injury were recruited 3 years after the original study in 1996. Twenty of the original 22 patients with FMS were available for reevaluation in 1999. A count of 18 tender points was conducted by thumb palpation, and tenderness thresholds were assessed by dolorimetry at 9 tender sites. All patients were interviewed about the presence and severity of neck and FMS-related symptoms. FMS was diagnosed by using the American College of Rheumatology 1990 criteria. Additional questions assessed measures of physical functioning and quality of life. RESULTS: Sixty percent of the 20 patients who had FMS in 1996 still had it 3 years later. All the 11 women with FMS, but only 1 of the 9 men with FMS, met FMS criteria in 1999. Only 1 of 58 patients who had no FMS in 1996 developed FMS. The quality of life scores for most patients improved, their tenderness scores decreased, and all remained employed. CONCLUSIONS: The outcome of posttraumatic FMS in patients with neck injury seems to be more favorable in men than in women; however, this finding should be interpreted with caution because of the small sample. Patients who do not develop FMS within 1 year of neck injury have a low probability of developing FMS in the future, comparable to the incidence of FMS in the general population.     

A Novel Liposomal Bupivacaine Formulation to Produce Ultralong-Acting Analgesia

Background: Currently available local anesthetics have relatively brief durations of action. An ultralong-acting local anesthetic would benefit patients with acute and chronic pain. The authors prepared and characterized a novel liposomal bupivacaine formulation using remote loading of bupivacaine along an ammonium sulfate gradient and assessed its efficacy in humans.

Methods: A large multivesicular liposomal bupivacaine formulation was prepared by subjecting small unilamellar vesicles to successive freeze-and-thaw cycles. Bupivacaine hydrochloride was then remotely loaded into the liposomes along an ammonium sulfate gradient ([(NH4)2SO4)]intraliposome/[(NH4)2SO4)]medium > 1,000). The liposomes were then characterized for size distribution; drug-to-phospholipid ratio; in vitro release profile at 4[degrees], 21[degrees], and 37[degrees]C; sterility; and pyrogenicity. Six subjects each received six intradermal injections in the lower back with 0.5 ml of 0.5, 1.0, and 2% liposomal bupivacaine; 0.5% standard bupivacaine; saline; and "empty" liposomes. Duration of analgesia was assessed using pinprick testing of the skin directly over the injection sites. Results were compared using the log-rank test.

Results: The mean large multivesicular vesicle size was 2,439 +/- 544 nm, with a drug-to-phospholipid ratio of 1.8, fivefold greater than results previously reported. In vitro release was slowest at 4[degrees]C. The median duration of analgesia with 0.5% standard bupivacaine was 1 h. The median durations of analgesia after 0.5, 1.0, and 2.0% liposomal bupivacaine were 19, 38, and 48 h, respectively. Neither saline nor "empty" liposomes produced analgesia.     

Robotic skeletonizing of the internal thoracic artery: is it safe?

BACKGROUND: The advantages of internal thoracic artery skeletonization include early high blood flow, a longer conduit, and less bleeding than pedicle internal thoracic artery grafts. Longer conduits are needed for complete endoscopic arterial revascularization. Therefore this study was designed to determine the feasibility and safety of internal thoracic artery skeletonization using the da Vinci robotic system (Intuitive Surgical, Sunnyvale, CA). METHODS: Nine dogs underwent bilateral robotic internal thoracic artery harvesting through three ports placed in the left chest. One internal thoracic artery was harvested as a pedicle in each dog, and the other was skeletonized. Internal thoracic artery blood flow was measured in each graft, and comparative endothelial histologic studies were performed. Data are mean +/- the standard error of the mean. RESULTS: All 18 internal thoracic arteries were harvested successfully. Skeletonized internal thoracic artery harvests required more time (48.0 minutes +/- 1.8) than pedicle internal thoracic artery harvests (39.0 minutes +/- 1.4; p < 0.05). Internal thoracic artery flows during the final intervals were similar (skeletonized = 30.0 mL/min +/- 2.4 vs pedicle = 31.5 mL/min +/- 1.8; p = 0.9). Free internal thoracic artery bleeding flow was similar in both groups (skeletonized = 162.0 mL/min +/- 3.0 vs pedicle = 189.0 mL/min +/- 2.4; p = 0.4). Histologically, both groups were similar with minimal endothelial damage. CONCLUSIONS: Robotically skeletonized harvesting is safe, but it requires more time (48.0 minutes +/- 1.8) than pedicle internal thoracic artery harvesting. Despite muted tactile feedback with robotics, neither technique was associated with histologic or functional damage. These encouraging results may represent an advantage for complete arterial revascularization in robotic coronary bypass patients.     

Respiratory morbidity in hospitalized Bedouins residing near an industrial park

The residents' concern about exposure to a chemical industrial park (IP), which includes the national toxic industrial waste site, prompted the authors to initiate this ecological study on the association between residing near the IP and being hospitalized for respiratory ailments in the local Bedouin population. The population was stratified by sex, age, and locality type (permanent settlements and traditional tribal settlements). The distance and wind direction from the IP were used as exposure indicators. Hospitalization data were obtained from the regional medical center. Increased hospitalization rates for chronic obstructive pulmonary disease and all respiratory diseases were found to be associated with residential proximity to the IP. Attributable risk for chronic obstructive pulmonary disease was 34.2% in male members of the traditional tribal settlements and 49.3% in female members of the permanent settlements.     

Effects of acute dynamic cardiomyoplasty in a goat model of chronic ventricular dilatation: part 1

BACKGROUND: The acute effects of cardiomyoplasty in an experimental model of chronic dilated heart have not been thoroughly investigated. Therefore, a model of chronic left ventricular (LV) dilatation was created to accurately determine actual changes shortly after passive and active wrapped skeletal muscle. METHODS: A carotid-jugular shunt model in 8 goats was used to induce progressive dilatation of the cardiac ventricles. Geometric modifications induced by the arteriovenous shunt were monitored by transthoracic echocardiography. After 8 weeks, cardiomyoplasty was performed, and the acute hemodynamic changes obtained with static cardiomyoplasty soon after the wrapping procedure were determined. Hence, hemodynamic variables recorded during assisted cardiac beats were then compared with data collected with unassisted cardiac beats using the conductance catheter method to generate pressure-volume loops. RESULTS: During electrical stimulation of the unconditioned skeletal muscle wrapped around the dilated left ventricle, a significant increase in stroke volume (117 +/- 48 mL versus 87 +/- 38 mL; p < 0.05) was observed. Early wrapped latissimus dorsi muscle activation also induced a reduction in LV end-systolic volume (from 51 +/- 28 mL to 27 +/- 14 mL; p < 0.05) when compared with unassisted LV contraction. CONCLUSIONS: In a chronic model of cardiac dilatation, acute dynamic cardiomyoplasty was shown to increase LV contractile performance and reduce LV volume. Further evaluation is necessary to show the effects of a conditioned wrapped muscle on LV systolic function and dimensions in the long-term.     

Orientation specificity of the Lactococcus lactis Chi site

BACKGROUND: In Escherichia coli, the Chi sequence modulates the activity of RecBCD, a powerful double-stranded (ds) DNA exonuclease/helicase. Chi attenuates RecBCD exonuclease activity and stimulates homologous recombination in an orientation-dependent manner. ChiEc is frequent and over-represented on its genome, which is thought to be related to its role in dsDNA break repair. We previously identified a Chi-like sequence (referred to as ChiLl) and an exonuclease/helicase in the Gram-positive bacterium Lactococcus lactis. ChiLl and RexAB are functional analogues of ChiEc and RecBCD. RESULTS: We report that ChiLl attenuates RexAB exonuclease activity and stimulates homologous recombination in an orientation-dependent manner. Analysis of ChiLl distribution on the L. lactis chromosome reveals that ChiLl is frequent, highly over-represented, and oriented with respect to the direction of replication. CONCLUSION: Our results show that a single orientation of ChiLl interacts with RexAB. The active orientation is preferentially found on the replication leading strand of the L. lactis genome, consistent with a primary role of ChiLl in repair of dsDNA breaks at the replication fork. We propose that orientation-dependence of Chi activity and over-representation of Chi sequences on bacterial genomes may be conserved properties of exonuclease/helicase-Chi couples. Other properties of the Chi sequence distribution on the genomes might reflect more specific characteristics of each couple and of the host.