The effects of hypertonic saline solution (7.5%) on coagulation and fibrinolysis: an in vitro assessment using thromboelastography

We studied the effects of hypertonic (7.5%) and normal saline on coagulation and fibrinolysis in an in vitro model using thromboelastography of human whole blood. Reaction times increased and alpha angles decreased with hypertonic saline replacement at 7.5% blood volume compared with similar dilution with normal saline. At 10% blood volume replacement with hypertonic saline, reaction and coagulation times were significantly increased and alpha angles were decreased. Clot lysis at 30 min was also significantly reduced. We conclude that 7.5% hypertonic saline solution has anticoagulant effects if it replaces 7.5% or more of blood volume.     

Fibrin sheath removal from central venous catheters: an internal snare manoeuvre.

BACKGROUND: Dysfunction of haemodialysis catheters is most commonly due to a narrowing of the catheter lumen and/or formation of a fibrin sheath around the catheter tip. Reported methods for restoring patency of the catheter lumen include passage of a J-tipped guide wire, passage of a biopsy brush through the catheter, or infusion of a thrombolytic agent into the catheter. While these methods are often effective, they suffer from several limitations. We present a minimally invasive technique to remove thrombi and debris from within the lumen of a partially thrombosed haemodialysis catheter while simultaneously stripping the fibrous sheath. METHODS: A 0.089 cm nitinol wire is bent to create a loop, which is then inserted via the catheters. Upon exiting the lumen of the catheters, the nitinol wire forces a snare open, which disrupts the fibrin sheath and catches intraluminal thrombi and debris. The technique requires no anaesthesia or recovery time. RESULTS: Initial clinical success in our series was achieved in all patients (7/7) as evidenced by restoration of target flow rates on subsequent haemodialysis. None of the patients experienced any complications as a result of the procedure. The catheter 2-, 4-, and 6-week primary success rates were 100% (8/8), 100% (8/8), and 100% (8/8) respectively with a mean duration of 17.1 weeks (range 8-40 weeks). CONCLUSIONS: The internal snare technique is an effective, inexpensive and minimally invasive approach to restoring patency to failed central venous access catheters.     

Postprocedural microembolic events following carotid surgery and carotid angioplasty and stenting

OBJECTIVE: The relative safety of percutaneous carotid interventions remains controversial. Few studies have used diffusion-weighted magnetic resonance imaging (DW-MRI) to evaluate the safety of these interventions. We compared the incidence and distribution of cerebral microembolic events after carotid angioplasty and stenting (CAS) with distal protection to standard open carotid endarterectomy (CEA) using DW-MRI. METHODS: From November 2004 through August 2006, 69 carotid interventions (27 CAS, and 42 CEA) were performed in 68 males at a single institution. Pre- and postprocedure DW-MRI exams were obtained on each patient undergoing CAS and the 20 most recent CEA operations. These 46 patients (47 procedures as one patient underwent bilateral CEAs in a staged fashion) constitute our study sample, and the hospital records of these patients (27 CAS and 20 CEA) were retrospectively reviewed. The incidence and location of acute, postprocedural microemboli were determined using DW-MRIs and assessed independently by two neuroradiologists without knowledge of the subjects' specific procedure. RESULTS: Nineteen CAS patients (70%, 95% confidence interval [CI]: 42%-81%) demonstrated evidence of postoperative, acute, cerebral microemboli by DW-MRI vs none of the CEA patients (0%, 95% CI: 0%-17%) (P < .0001). Of the 19 CAS patients with postoperative emboli, nine (47%) were ipsilateral to the index carotid lesion, three (16%) contralateral, and seven (36%) bilateral. The median number of ipsilateral microemboli identified in the CAS group was 1 (interquartile ranges [IQR]: 0-2, range 0-21). The median number of contralateral microemboli identified in the CAS group was 0 (IQR: 0-1, range 0-5). Three (11%) CAS patients experienced temporary neurologic sequelae lasting less than 36 hours. These patients suffered 12 (six ipsilateral and six contralateral), 20 (19 ipsilateral and one contralateral), and zero microemboli, respectively. By univariate analysis, performing an arch angiogram prior to CAS was associated with a higher risk of microemboli (median microemboli 5 vs none, P =.04) CONCLUSIONS: Although our early experience suggests that CAS may be performed safely (no permanent neurologic deficits following 27 consecutive procedures), cerebral microembolic events occurred in over two-thirds of the procedures despite the uniform use of distal protection. Open carotid surgery in this series seems to offer a lower risk of periprocedural microembolic events detected by DW-MRI.     

Ovine forestomach matrix biomaterial is a broad spectrum inhibitor of matrix metalloproteinases and neutrophil elastase

Proteases play a critical role in the ordered remodelling of extracellular matrix (ECM) components during wound healing and tissue regeneration. However, the usually ordered proteolysis is compromised in chronic wounds due to over‐expression and high concentrations of matrix metalloproteinase's (MMPs) and neutrophil elastase (NE). Ovine forestomach matrix (OFM) is a decellularised extracellular matrix‐based biomaterial developed for tissue regeneration applications, including the treatment of chronic wounds, and is a heterogeneous mixture of ECM proteins and proteoglycans that retains the native structural and functional characteristics of tissue ECM. Given the diverse molecular species present in OFM, we hypothesised that OFM may contain components or fragments that inhibit MMP and NE activity. An extract of OFM was shown to be a potent inhibitor of a range of tissue MMPs (IC₅₀s = 23 ± 5 to 115 ± 14 µg/ml) and NE (IC₅₀ = 157 ± 37 µg/ml), and was more potent than extracts prepared from a known protease modulating wound dressing. The broad spectrum activity of OFM against different classes of MMPs (i.e. collagenases, gelatinases and stromelysins) may provide a clinical advantage by more effectively addressing the protease imbalance seen in chronic wounds.     

The conditional probabilities of survival in patients with anaplastic astrocytoma or glioblastoma multiforme

BACKGROUND: By the use of conditional probabilities of survival, we studied the yearly survival rates for individual tumor survivors. METHODS: Conditional survival rate was estimated in 114 consecutive patients with anaplastic astrocytoma or glioblastoma multiforme. Conditional probabilities of surviving some years given survival to a specific period of time after craniotomy and 95% confidence intervals were calculated in the individual tumor survivors. RESULTS: The estimated median survival was 30 months for 45 patients with anaplastic astrocytoma and 12 months for 69 patients with glioblastoma multiforme. The conditional probabilities of surviving next one year given survival to 1 year, 2 years, 3 years, 4 years, or 5 years after craniotomy for anaplastic astrocytoma were 86.2%, 75.0%, 85.9%, 77.8%, or 85.7%, respectively; for glioblastoma multiforme 64.8%, 58.7%, 85.7%, 80.0%, or 75.0%, respectively. The conditional probability of surviving to 5 years given survival to 2 years after craniotomy for anaplastic astrocytoma, i.e., surviving an additional 3 years, was 50.1%, which was better than observed 5-year survival rate (28.6%); for glioblastoma multiforme it was 40.2%, which also was better than observed 5-year survival rate (12.4%). CONCLUSIONS: The conditional probability of survival was a good method to clinically predict yearly survival rate for individual tumor survivors. In addition, the method can estimate the probabilities of surviving next some years given survival to a specific period of time after craniotomy. It also showed a more encouraging result than observed survival rate in patients with supratentorial malignant astrocytomas.     

A comparative study of three warming interventions to determine the most effective in maintaining perioperative normothermia

Perioperative hypothermia poses a challenge because of its deleterious effects on patient recovery. The current practice of applying two cotton blankets on patients during surgery is thought to be less ideal than using reflective insulation or forced-air warming. We studied 300 patients who underwent unilateral total knee replacement and were randomized equally to three groups: (a) the two-cotton-blanket group, (b) the one-reflective-blanket with one-cotton-blanket group, and (c) the forced-air-warming with one-cotton-blanket group. Tympanic temperature readings were taken before surgery in the induction room, on arrival at the recovery room, and at 10-min intervals until discharge from the recovery room. On arrival at the recovery room, the forced-air-warming group had significantly higher temperatures (adjusted for sex, age, and patient's induction room temperature) of 0.577 degrees C +/- 0.079 degrees C (95% confidence interval [CI], 0.427-0.726; P < 0.001) and 0.510 degrees C +/- 0.08 degrees C (95% CI, 0.349-0.672; P < 0.001) more than the reflective-blanket and two-cot-ton-blanket groups, respectively. The forced-air-warming group took a significantly (P < 0.001) shorter time of 18.75 min (95% CI, 13.88-23.62) to achieve a temperature of 36.5 degrees C in the recovery room as compared with 41.78 min (95% CI, 36.86-46.58) and 36.43 min (95% CI, 31.23-41.62) for the reflective-blanket and two-cotton-blanket groups, respectively. The reflective technology was less effective than using two cotton blankets, and the forced-air warming was most efficient in maintaining perioperative normothermia. IMPLICATIONS: Perioperative hypothermia has deleterious effects on patient recovery. We found in patients having knee surgery that reflective technology was less effective than using two cotton blankets, whereas active surface warming with the forced-air method was most effective in maintaining normothermia.     

Differential Effect of Diarrhea on FK506 Versus Cyclosporine A Trough Levels and Resultant Prevention of Allograft Rejection in Renal Transplant Recipients

Diarrhea is the most frequently reported adverse event in patients treated with mycophenolate mofetil. Twenty-six renal transplant patients on a mycophenolate mofetil-based immunosuppressive regime with persistent afebrile diarrhea were examined. Diarrhea caused a significant rise in FK-506 trough levels despite intake of stable doses, necessitating FK-506 dose reductions of 30% to obtain pre-diarrhea trough levels. In contrast, trough levels of cyclosporine A remained stable without dose adjustments. This suggests that absorption and/or metabolism is differentially altered for FK506 compared with cyclosporine A in patients with diarrhea. In nine patients mycophenolate mofetil was reduced or stopped because of persistent diarrhea without identifiable cause. This resulted in end-stage renal disease because of chronic rejection in two patients, and in acute rejection in two patients, all taking FK506 and steroids. Therefore, dose adjustments of FK506 in patients with diarrhea must be carefully monitored, especially when doses of mycophenolate mofetil are also reduced.     

Management of bacterial peritonitis and exit‐site infections in continuous ambulatory peritoneal dialysis*

SUMMARY: Peritonitis and exit‐site infections remain the most important limitations to the delivery of continuous ambulatory peritoneal dialysis (CAPD). Contamination of the peritoneum, from endogenous or exogenous sources, is responsible for most peritonitis episodes. Patients usually present with a cloudy bag, although other causes should be distinguished. Clinical suspicion of peritonitis should be followed rapidly by microbiological examination and empirical treatment. Microbiological confirmation allows for subsequent treatment based on sensitivities. Other interventions such as catheter removal may be appropriate in some patients. Exit‐site infections should also be identified and treated early. Peritonitis may be further prevented by adequate exit‐site care, hygienic methods, and techniques to minimise early contamination of the exit site. Mupirocin may also have a role in preventing infections caused by Staphylococcus aureus.     

Problems and advantages of continuous renal replacement therapy*

SUMMARY: The continuous replacement of renal function must facilitate fluid and solute homeostasis, nutrition and vital organ function, and, where possible, hasten the recovery of renal function. Difficulties with anticoagulation, biocompatibility, mobility and cost remain obstacles to be overcome. the use of continuous renal replacement therapy (CRRT) to remove systemic inflammatory mediators is yet to be confirmed. Although survival benefits of CRRT over intermittent dialysis remain controversial, the slow continuous removal of fluid, acid and solute has a number of advantages, especially where patients are haemodynamically unstable.