Performance of polymethyl pentene oxygenators for neonatal extracorporeal membrane oxygenation: a comparison with silicone membrane oxygenators

OBJECTIVE: To review the performance of polymethyl pentene versus silicone oxygenators in terms of efficiency in priming and oxygenation, oxygenator resistance, requirements for coagulation proteins and consumption of blood products, for neonatal extracorporeal membrane oxygenation (ECMO) patients. STUDY DESIGN: Forty consecutive neonates were selected retrospectively pre- and post-introduction of the new polymethyl pentene (PMP) oxygenators. They formed two equal groups. After calculation of the sample size, data were collected from ELSO registry forms and patient records. Results were analysed using parametric and non-parametric tests. RESULTS: Neonatal PMP (N-PMP) oxygenators were smaller, faster and easier to prime. They were less efficient than silicone oxygenators, especially in carbon dioxide elimination, and, therefore, required higher sweeps. The preservation of coagulation proteins was significantly better, but there was no reduction in the consumption of blood products, despite having less than half the surface area and significantly lower blood path resistance. CONCLUSION: Small PMP oxygenators (Medos Hilite 800 LT) provide adequate gas exchange and offer technical advantages in terms of more efficient priming, reduced haemodynamic resistance and better control and preservation of coagulation proteins than silicone oxygenators.     

A potential propensity for failure secondary to clot embolism in neonatal ECMO

OBJECTIVE: To report a single case of oxygenator failure caused by clot embolism originating from the bladder; and to discuss some preventative options. CASE REPORT: A 2.5 kg neonate with a diagnosis of influenza A received veno-arterial (V-A) extracorporeal membrane oxygenation (ECMO) for cardiorespiratory support. Halfway through treatment, she underwent an elective circuit change for numerous clots in her circuit. The patient continued to consume vast quantities of platelets and developed a fatal oxygenator failure after 18 days. DISCUSSION: Amongst the factors influencing the outcome in events of a sudden unexpected oxygenator failure are the severity of patient illness, the size of the clot relative to the size of the oxygenator, the availability of a previously primed circuit and the ease and speed of priming a new oxygenator. CONCLUSION: There is a need for improvement in the design of small oxygenators and ECMO circuits. Adjustment of the coagulation parameters and lowering the tolerance towards clots in the circuit by electively changing them may reduce the incidence of sudden unexpected oxygenator failure. However, using a slightly larger Medos oxygenator may gain valuable time needed to arrange an oxygenator/circuit change.     

Outcomes of infection following pediatric spinal fusion

Background

Removal of instrumentation is often recommended as part of treatment for spinal infections, but studies have reported eradication of infection even with instrumentation retention by using serial débridements and adjuvant antibiotic pharmacotherapy. We sought to determine the effect of instrumentation retention or removal on outcomes in children with spinal infections.

Methods

We retrospectively reviewed the cases of patients who experienced early (< 3 mo) or late (≥ 3 mo) infected spinal fusions. Patients were evaluated at least 2 years after eradication of the infection using the following protocol outcomes: follow-up Cobb angle, curve progression and nonunion rates.

Results

Our sample included 35 patients. The mean age at surgery was 15.1 ± 6.0 years, 65.7% were girls, and mean follow-up was 41.7 ± 26.9 months. The mean Cobb angle was 63.6° ± 14.5° preoperatively, 29.4° ± 16.5° immediately after surgery and 37.2° ± 19.6° at follow-up. Patients in the implant removal group (n = 21) were more likely than those in the implant retention group (n = 14) to have a lower ASA score (71.4% v. 28.6%, p = 0.03), fewer comorbidities (66.7% v. 21.4%, p = 0.03), late infections (81.0% v. 14.3%, p = 0.01) and deep infections (95.2% v. 64.3%, p = 0.03). Implants were retained in 12 of 16 (75.0%) patients with early infections and 2 of 19 (10.5%) with late infections. Patients with implant removal had a higher pseudarthrosis rate (38.1% v. 0%, p = 0.02) and a faster curve progression rate (5.8 ± 9.8° per year v. 0.2 ± 4.7° per year, p = 0.04).

Conclusion

Implant retention should be considered, irrespective of the timing or depth of the infection.     

Effect of Parkinson’s Disease on Hemiarthroplasty Outcomes After Femoral Neck Fractures

BackgroundThe purpose of this study was to evaluate the outcomes following hemiarthroplasty (HA) for femoral neck fractures (FNFs) in patients with Parkinson’s disease (PD) compared with patients without PD.MethodsThis was a retrospective review utilizing the Nationwide Readmissions Database, a national database incorporating inpatient hospitalization information. Using the Nationwide Readmissions Database, patients who underwent HA for FNF between 2010-2014 were identified. International Classification of Diseases, 9th Revision, codes were used to find a subset of patients with PD. Primary outcomes of interest included death, hospital readmission, periprosthetic fracture, postoperative dislocation, any revision surgery, and revision surgery for instability, fracture, or infection.ResultsThere were a total of 7721 (4%) patients with PD. There was no difference in the risk of death or any postoperative complications during index hospitalization for these patients. However, PD patients had an increased risk of hospital readmission (odds ratio [OR] = 1.13, 95% confidence interval [CI]: 1.02-1.26) and postoperative dislocation (OR = 2.10, 95% CI: 1.58-2.80) within 90 days of surgery. PD patients also had an increased risk of revision surgery for instability (OR = 2.20, 95% CI: 1.48-3.28), despite no difference in the risk of any revision surgery, revision surgery for fracture, or revision surgery for infection.ConclusionIn this retrospective cohort study, PD patients who underwent a HA for FNF had a greater risk of postoperative dislocation and revision surgery for instability within 90 days. These findings are not only important to consider when managing these at-risk patients but also stress the need to allocate operative and postoperative resources to prevent and treat instability.Level of Evidence3 (Retrospective cohort study).     

The effect of post space preparation in teeth obturated with Mineral Trioxide Aggregate evaluated using a fluid filtration system

The aim of this study was to evaluate the seal of a 4-mm Mineral Trioxide Aggregate (MTA) filling after post space preparation. Forty single-rooted premolar teeth without curved root anatomy and fractures were selected. The root length was standardized to 12 mm by removing excess from the apical end. The roots were instrumented to a 50 K-file by the step-back technique. The roots were randomly divided into groups A and B, of fifteen each. In group A, the canals were obturated with 7 mm of white MTA. After 24 h, 3 mm of MTA was removed to simulate post space preparation using a long shank diamond round bur. In group B, the canals were filled with 4 mm of white MTA. All samples were attached to a fluid filtration device. Measurements (μl min?1 cm H?O?1) were taken every 2 min, for 10 min and data were analyzed by an independent t-test (P > 0.05). Fluid transport averaged in groups A and B at 9.2 × 10??, and 11.8 × 10?? μl min?1 cm H?O?1, respectively. Independent t-test showed no significant difference between the groups (P < 0.05). Removing set MTA using a round bur for post space preparation does not affect its sealing ability, when 4 mm of MTA remains.     

Mechanisms underlying erythrocyte and endothelial nitrite reduction to nitric oxide in hypoxia: role for xanthine oxidoreductase and endothelial nitric oxide synthase

Reduction of nitrite (NO(2)(-)) provides a major source of nitric oxide (NO) in the circulation, especially in hypoxemic conditions. Our previous studies suggest that xanthine oxidoreductase (XOR) is an important nitrite reductase in the heart and kidney. Herein, we have demonstrated that conversion of nitrite to NO by blood vessels and RBCs was enhanced in the presence of the XOR substrate xanthine (10 micromol/L) and attenuated by the XOR inhibitor allopurinol (100 micromol/L) in acidic and hypoxic conditions only. Whereas endothelial nitric oxide synthase (eNOS) inhibition had no effect on vascular nitrite reductase activity, in RBCs L-NAME, L-NMMA, and L-arginine inhibited nitrite-derived NO production by >50% (P<0.01) at pH 7.4 and 6.8 under hypoxic conditions. Western blot and immunohistochemical analysis of RBC membranes confirmed the presence of eNOS and abundant XOR on whole RBCs. Thus, XOR and eNOS are ideally situated on the membranes of RBCs and blood vessels to generate intravascular vasodilator NO from nitrite during ischemic episodes. In addition to the proposed role of deoxyhemoglobin, our findings suggest that the nitrite reductase activity within the circulation, under hypoxic conditions (at physiological pH), is mediated by eNOS; however, as acidosis develops, a substantial role for XOR becomes evident.