Evaluation of the impact of nasal colonization with methicillin-resistant Staphylococcus aureus on left ventricular assist device infections.

In this retrospective cohort study, we evaluated the predictive value of methicillin-resistant Staphylococcus aureus (MRSA) nasal swabs for the development of MRSA infections in patients with left ventricular assist devices. In 106 patients, the MRSA nasal swab had a negative predictive value of 92.9% demonstrating a potential role in antibiotic de-escalation.

Evaluation of aspirin platelet inhibition in left ventricular assist device population.

INTRODUCTION: Aspirin therapy is recommended in durable left ventricular assist device (LVAD) patients to prevent thromboembolic complications. Up to 30% of patients treated with aspirin may demonstrate aspirin resistance, which has been related to thrombotic complications. However, it is unknown whether individual patients exhibit temporal alterations in aspirin sensitivity during LVAD support. We hypothesized that aspirin platelet inhibition would wane after the initial postimplant period. METHODS: This was a retrospective, observational, single center study conducted at an academic medical center. This study evaluated changes in aspirin platelet inhibition over the first 6 months of LVAD support. Patients who underwent placement of centrifugal LVAD with aspirin platelet sensitivity assays were included for analysis. Aspirin responsiveness was assessed postimplant after 5 days, 3 months, and 6 months. RESULTS: A total of 28 patients were included for analysis of which 7% of patients were aspirin resistant initially. At 3 months, 32% (odds ratio [OR], 6.1, p = .03) of patients were aspirin resistant and 28% (OR, 4.1, p = .1) at 6 months. Over the first 3 months postimplant, the odds of aspirin resistance increased sixfold and remained relatively constant at 6 months. Patients who were aspirin resistant and received an increase in aspirin dose at 3 months subsequently had a sensitive ARU at 6 months. CONCLUSION: Aspirin responsiveness not only varies between patients but can significantly wane within individual LVAD patients over time. Additional study is needed to determine if monitoring aspirin resistance may prevent thrombotic complications after LVAD implantation.

Effect of Phenylephrine Push Before Continuous Infusion Norepinephrine in Patients With Septic Shock.

BACKGROUND: IV pushes of phenylephrine may be used for patients with septic shock with the intent of rapidly achieving mean arterial pressure (MAP) goals. However, the clinical effectiveness and safety of this approach are unclear. RESEARCH QUESTION: In patients with septic shock, is administration of a phenylephrine push before norepinephrine initiation associated with a higher incidence of hemodynamic stability? METHODS: This retrospective, multicenter cohort study included adult patients with septic shock initiated on norepinephrine. Propensity scores for initial phenylephrine push receipt were generated, and patients receiving an initial phenylephrine push were propensity score-matched 1:2 to those not receiving an initial phenylephrine push. The primary outcome was achievement of hemodynamic stability (defined as maintaining MAP of ≥ 65 mm Hg for at least 6 h without an increase in continuous infusion vasoactive agent dosage) within 3 and 12 h of norepinephrine initiation. RESULTS: Of 1,317 included patients, 181 received an initial phenylephrine push; 141 phenylephrine push patients were matched to 282 patients not receiving a phenylephrine push. More patients who received a phenylephrine push achieved hemodynamic stability at hour 3 than those who did not receive a phenylephrine push (28.4% vs 18.8%; risk difference, 10%; 95% CI, 0.9%-18%). Phenylephrine push receipt was associated independently with hemodynamic stability within 3 h (adjusted OR, 1.8; 95% CI, 1.09-2.97), but not at 12 h (adjusted OR, 1.42; 95% CI, 0.93-2.16). Phenylephrine push receipt was associated independently with higher ICU mortality (adjusted OR, 1.88; 95% CI, 1.1-3.21). INTERPRETATION: Phenylephrine pushes were associated with a higher incidence of early, but not sustained, hemodynamic stability and were associated independently with higher ICU mortality. Caution is warranted when clinicians are considering the use of phenylephrine pushes in patients with septic shock.

Effectiveness, Safety, and Economic Comparison of Inhaled Epoprostenol Brands, Flolan and Veletri, in Acute Respiratory Distress Syndrome.

Background: No previous studies exist examining 2 inhaled epoprostenol formulations in an acute respiratory distress syndrome (ARDS) patient population. Objective: The study aim was to evaluate a formulary conversion from inhaled Flolan to Veletri to determine the impact on effectiveness, safety, and cost in patients with ARDS. Methods: This was a single-center, retrospective, matched cohort observational study at a tertiary care academic medical center. Patients included were mechanically ventilated, adult patients with ARDS receiving inhaled Flolan or Veletri for ≥1 hour in the intensive care unit. Results: A total of 132 patients were included in the matched cohort. There was no difference detected in change in partial pressure of arterial O2/fraction of inspired O2 (PaO2/FiO2) ratio after 1 hour of therapy between the inhaled Flolan and Veletri groups (27.2 ± 46.2 vs 30 ± 68 mm Hg, P = 0.78). Significant differences in secondary outcomes included incidence of hypotension (83% vs 95.5%, P = 0.04) and thrombocytopenia (9.1% vs 29.5%, P < 0.01) in the inhaled Flolan and Veletri groups, respectively, with no difference in cost per duration of therapy (P = 0.29). Conclusions and Relevance: There was no difference in the change in PaO2/FiO2 ratio after 1 hour of therapy between inhaled Flolan and Veletri in an ARDS patient population. The formulary conversion from inhaled Flolan to Veletri was likely justified.

Effectiveness, safety, and Economic Comparison of Two Inhaled Epoprostentol Products (Flolan and Veletri) in Cardiothoracic Surgery Patients.

BACKGROUND: No previous studies exist examining two inhaled epoprosternol formulations (Flolan compared with Veletri) in a homogenous cardiothoracic surgery patient population. OBJECTIVE: To compare the impact of inhaled Flolan and inhaled Veletri on the effectiveness, safety, or cost in cardiothoracic surgery patients. MATERIALS AND METHODS: This was a retrospective, noninferiority study comparing inhaled Flolan and inhaled Veletri in cardiothoracic surgery patients. Participants included were ≥18 years old, admitted to the cardiothoracic intensive care unit, and received inhaled Flolan or inhaled Veletri therapy for ≥1 hour. RESULTS: A total of 244 patients were included in the primary outcome analysis (122 patients per group). The primary outcome, change in the partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) ratio 1 hour after administration of inhaled Flolan or inhaled Veletri, did not cross the lower limit of the noninferiority margin (95% CI = -14.8 to 65.4). Significant differences in secondary outcomes included duration of mechanical ventilation (4.4 vs 2.6 days; P < 0.01), number of tracheostomies (24 vs 9; P = 0.01), number of patients initiated on dialysis (25 vs 12; P = 0.02), and cost per median duration of therapy ($257 vs $183; P = 0.02) in the inhaled Flolan and inhaled Veletri groups, with the average duration of therapy being 1.6 and 1.3 days, respectively. CONCLUSIONS AND RELEVANCE: Inhaled Veletri was demonstrated to be non-inferior to inhaled Flolan when comparing change in PaO2/FiO2 ratio 1 hour post -therapy initiation,and inhaled Veletri was an acceptable alternative to inhaled Flolan in a cardiothoracic surgery patient population.

Reconstitution of KCNE1 into lipid bilayers: comparing the structural, dynamic, and activity differences in micelle and vesicle environments.

KCNE1 (minK), found in the human heart and cochlea, is a transmembrane protein that modulates the voltage-gated potassium KCNQ1 channel. While KCNE1 has previously been the subject of extensive structural studies in lyso-phospholipid detergent micelles, key observations have yet to be confirmed and refined in lipid bilayers. In this study, a reliable method for reconstituting KCNE1 into lipid bilayer vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho(1'-rac-glycerol) (sodium salt) (POPG) was developed. Microinjection of the proteoliposomes into Xenopus oocytes expressing the human KCNQ1 (K(V)7.1) voltage-gated potassium channel led to nativelike modulation of the channel. Circular dichroism spectroscopy demonstrated that the percent helicity of KCNE1 is significantly higher for the protein reconstituted in lipid vesicles than for the previously described structure in 1.0% 1-myristoyl-2-hydroxy-sn-glycero-3-phospho(1'-rac-glycerol) (sodium salt) (LMPG) micelles. SDSL electron paramagnetic resonance spectroscopic techniques were used to probe the local structure and environment of Ser28, Phe54, Phe57, Leu59, and Ser64 of KCNE1 in both POPC/POPG vesicles and LMPG micelles. Spin-labeled KCNE1 cysteine mutants at Phe54, Phe57, Leu59, and Ser64 were found to be located inside POPC/POPG vesicles, whereas Ser28 was found to be located outside the membrane. Ser64 was shown to be water inaccessible in vesicles but found to be water accessible in LMPG micelle solutions. These results suggest that key components of the micelle-derived structure of KCNE1 extend to the structure of this protein in lipid bilayers but also demonstrate the need to refine this structure using data derived from the bilayer-reconstituted protein to more accurately define its native structure. This work establishes the basis for such future studies.