The effect of calcium ions on the activated partial thromboplastin time of heparinized plasma

The effect of calcium chloride (CaCl2) on the activated partial thromboplastin time (aPTT) of heparinized plasma was studied. The aPTT ratio (heparinized plasma:control plasma) increased as the CaCl2 concentration to recalcify the plasma was increased from 15 to 35 mmol/L CaCl2. Platelet-poor plasma from patients receiving intravenous heparin, and in vitro heparinized plasmas from either coumarinized patients or plasma depleted of the vitamin K-dependent factors, displayed the calcium-dependent increase in the aPTT ratio. The magnitude of the calcium-dependent change in the aPTT ratio was similar for the three partial thromboplastins studied. Heparinized blood collected in 3.2% and 3.8% citrate demonstrated the calcium-dependent increase in the aPTT ratio. The authors have also studied the effect of the divalent cations (Ca+2, Mg+2, Zn+2, and Sr+2) on the anti-Factor Xa activity of heparin to determine whether the calcium-dependent increase in the aPTT was due to an increase in the anti-Factor Xa activity. The anti-Factor Xa activity of heparin was measured using chromogenic substrate S-2251, purified Factor Xa, and excess antithrombin III. The anti-Factor Xa activity of heparinized plasma increased 2.4-2.8-fold as the divalent cation concentration was increased from 0-5 mmol/L. Similar results were obtained using purified bovine Factor Xa, antithrombin III, and heparin in the absence of plasma. These results suggest that divalent cations play an important role in modulating heparin's anticoagulant activity in vitro. In addition, the CaCl2 concentration used to recalcify plasma is an important variable that modifies heparin sensitivity of the aPTT. Furthermore, divalent cations play an important role in regulating the anti-Factor Xa activity of heparin in vitro.     

The ileoanal J pouch: radiographic evaluation

Endorectal ileoanal pull-through offers an attractive alternative to proctocolectomy and ileostomy for patients with ulcerative colitis, Gardner syndrome, and familial polyposis. To our knowledge, a careful radiographic analysis of the ileum, ileal pouch, and ileoanal anastomosis after ileoanal pull-through has not been reported. Thirty-two patients with ulcerative colitis, Gardner syndrome, and familial polyposis underwent colectomy, mucosal proctectomy, and endorectal ileoanal pull-through of a 15-cm ileal "J" pouch and loop ileostomy. Twenty-five (78%) of 32 of all the pouches radiographically demonstrated spiral folds extending from the middle of the pouch to the pectinate line. Other radiographic features included a mesenteric mass effect, pseudopolyps, and a central lucency that indicated intrapouch sutures. Radiographs provide useful information in the postoperative management of the ileal pull-through.     

Migration Patterns for Revision Total Hip Arthroplasty in the United States as Reported in the American Joint Replacement Registry

BackgroundRevision total hip arthroplasty (revTHA) is associated with higher rates of complications and greater costs than primary procedures. The aim of this study is to evaluate the effect of hospital size, teaching status, and indication for revTHA, on migration patterns in patients older than 65 years old.MethodsAll THAs and revTHAs reported to the American Joint Replacement Registry from 2012 to 2018 were included and merged with the Centers for Medicare and Medicaid Services database. Migration rate was defined as a patient’s THA and revTHA procedures that were performed at separate institutions by different surgeons. Migratory patterns were recorded based on hospital size, teaching status, and indication for revTHA. Analyses were performed by statisticians.ResultsThe number of linked procedures included was 11,906. Migration rates in revTHA due to infection were higher for small hospitals than large hospitals (46.6% vs 28.6%, P < .0001). Migration rates were higher comparing non-teaching with teaching hospitals (55% vs 34%, P < .0001). This difference was significant for periprosthetic fractures (70.6% vs 37.2%, P = .005), instability (56.5% vs 35.5%, P = .04), and mechanical complications (88.9% vs 34.7%, P < .05). Most patients migrated to medium or large hospitals rather than small hospitals (89% vs 11%, P < .0001) and to teaching rather than non-teaching institutions (82% vs 18%, P < .0001).ConclusionHospital size and teaching status significantly affected migration patterns for revTHA. Migration rates were significantly higher in small non-teaching hospitals in revTHA due to infection, periprosthetic fracture, instability, and mechanical complications. Over 80% of patients migrated to larger teaching hospitals.     

Early hospital discharge of children with cancer treated for fever and neutropenia: identification and management of the low-risk patient

Children with leukemia and solid tumors are often hospitalized for empiric broad-spectrum antibiotic therapy because of fever during periods of chemotherapy-induced neutropenia. Conventional practice dictates that parenteral antibiotics be continued until the patient is afebrile and has recovered from neutropenia, ie, until the absolute neutrophil count (ANC) exceeds 500 cells per cubic millimeter. However, the practice in our center has been to discontinue parenteral antibiotic therapy and discharge many such patients before resolution of neutropenia. Since the feasibility and safety of this approach has not been studied, we reviewed the records of 114 consecutive hospitalizations for fever and neutropenia in 61 patients during a 13-month period. Seventy-seven children (68%) were discharged to their homes while still neutropenic after they had been afebrile for 1 to 2 days on parenteral antibiotics, had negative blood cultures, appeared well, and usually had some evidence of bone marrow recovery. Five patients (4.4%) developed recurrent fever and required rehospitalization within 7 days of discharge. Only three of the 77 patients (3.9%) who were sent home with neutropenia had recurrent fever. Each had a brief and uneventful second hospitalization. Two of the 37 children discharged with an ANC over 500 cells per cubic millimeter required rehospitalization. A declining ANC and advanced malignancy were risk factors in predicting recurrence of fever following discharge. A rising monocyte count was a predictor of imminent recovery from neutropenia. These results suggest that "early" discharge of an afebrile yet still neutropenic patient is safe when the patient is in remission, has no evidence of serious infection, appears clinically stable, and has indications of bone marrow recovery. The conventional approach of routinely continuing the hospitalization until resolution of neutropenia may be unnecessary in such low-risk patients.     

Postpartum return to smoking: who is at risk and when

PURPOSE: Despite high rates of spontaneous and assisted smoking cessation during pregnancy, postpartum maintenance is disappointingly low. Predictors of return to smoking remain unclear, thus limiting the development of interventions that could protect the health of women and their children. This study followed women who had participated in a prenatal smoking cessation intervention trial and successfully stopped smoking to address two aims: (1) describe the probability of relapse in confirmed quitters during the first 6 months after the birth, and (2) identify factors that increase relapse. DESIGN: Prospective design during pregnancy and retrospective report at 6 months postpartum used survival analysis with return to smoking as the dependent variable and the Cox proportional hazards regression technique. MEASURES: Questionnaires were used at the first prenatal visit and telephone interviews at the 26th week of pregnancy and 6 months postpartum. Nonsmoking after the 20th week was measured by urine cotinine tests (m = 3); nonsmoking postpartum was measured by retrospective self-report. SETTING: The setting was an HMO-based group practice in Los Angeles. SUBJECTS: Subjects were white, black, and Hispanic women (n = 127) available for follow-up. RESULTS: The proportion of the sample classified as relapsers at 6 months postpartum was 62.9%. The final model identified the following risk factors for smoking: taking puffs in late pregnancy and having friends who smoke at the first prenatal visit, less confidence in mid-pregnancy that they could maintain nonsmoking postpartum, and a partner who smokes postpartum. CONCLUSIONS: Intervention should begin in late pregnancy, and smoking networks, including partner smoking, should be addressed.     

Long-term enteral access in aspiration-prone patients

Aspiration pneumonia is a serious complication of enteral feeding. Many critically ill patients are particularly at risk for aspiration. Few studies have rigorously compared various access devices. Risk factors for aspiration and studies examining aspiration associated with enteral feeding devices are reviewed. We recommend a surgical jejunostomy for all patients at high risk for aspiration who require more than 3 weeks of enteral nutrition support.     

The vasa vasorum and angioplasty

Interruption of flow in the vasa vasorum may lead to medial necrosis and aneurysm formation. The purpose of this study was to determine whether angioplasty produces significant alterations in the morphology or blood flow of the vasa vasorum of the dilated artery. The morphology of the canine vasa vasorum was studied before and after angioplasty; in a separate experiment vessel wall blood flow (VWBF) in canine carotid arteries was measured after angioplasty to determine whether physiologic regulation of the blood flow was disrupted by arterial dilation. No morphologic changes could be demonstrated in the vasa vasorum of the dilated artery; however, VWBF was increased by 1194 +/- 215% (mean +/- standard error, p less than 0.01) between 90 and 120 minutes after angioplasty. VWBF in the adjacent nondilated arterial segment was also increased (720 +/- 177% between 10-30 minutes, p less than 0.01) but returned toward normal after 60 minutes. Adenosine caused a "paradoxical" decrease in VWBF (p less than 0.05) of the dilated arterial segment while causing increased VWBF (p less than 0.05) in the thoracic aorta. Angioplasty appears to produce persistent hyperemia in the dilated arterial wall. A paradoxical response to adenosine suggests that vasa vasorum in the dilated arterial segment are maximally vasodilated. This may be due to mechanical disruption of vasomotor tone or to release of vasoactive substances.