Stability of Whole Blood Electrolyte Specimens at Room Temperature vs. Slushed Ice Conditions.

BACKGROUND: Data on the stability of whole blood electrolytes is limited to small sample sizes. We sought to determine the stability of whole blood electrolytes under room temperature and slushed iced conditions in human patients at a major hospital center. METHODS: Whole blood samples were obtained from 203 patients hospitalized for various pathophysiological conditions. Electrolyte concentrations of sodium, potassium [K+], ionized calcium, and chloride were measured at 5 different timepoints spanning 3 h. Samples were stored at room temperature (22-24 °C) or under slushed ice conditions (0.1-0.2 °C) before analysis. RESULTS: Under both conditions, sodium, ionized calcium, and chloride did not show a measurable change up to 109 min compared to baseline; however, the mean increase in [K+] over 138 min of storage in slushed ice was 0.0032 (0.0021 [5th percentile] to 0.0047 [95th percentile]) mmol/L/min (adjusted R2 = 0.62, P < 0.001). Five percent of the specimens demonstrated a ≥0.3 mmol/L change in [K+] from baseline after 67 min of storage in slushed ice. In contrast, 1% of the specimens stored at room temperature showed the same change at the same timepoint. CONCLUSIONS: Whole blood sodium, [K+], ionized calcium, and chloride concentrations remain stable for at least 109 min at room temperature. However, whole blood specimens stored in slushed ice for not more than 67 min exhibit a 5% probability that the [K+] concentration will increase by at least 0.3 mmol/L compared to baseline. The other analytes do not destabilize for up to 178 min of slushed ice storage.

Stability of Whole Blood Lactate Specimens at Room Temperature Versus Slushed Ice Conditions.

BACKGROUND: There are limited data on lactate stability in whole blood. The purpose of this study was to determine whole blood lactate stability at room temperature and in slushed ice conditions. METHODS: An equal number of arterial and venous samples were obtained from 202 subjects hospitalized for various pathophysiological conditions. Whole blood lactate concentration was measured over 5 different times spanning 80-90 min in a blood gas lab at a major hospital center. Samples were stored at room temperature (22-24°C) or in slushed ice conditions (0.1-0.2°C) before analysis. RESULTS: The mean increase in lactate concentration was 0.001 mmol/L/min in samples on slushed ice over 90 min. However, at room temperature conditions, the mean increase in lactate concentration was 0.008 mmol/L/min regardless of whether the sample was arterial or venous. An increase in whole blood lactate concentration of ≥ 0.4 mmol/L occured after 45 min at room temperature, with 5% of all whole blood specimens demonstrating a meaningful change at ≤ 20 min. The ≥ 0.4 mmol/L change in whole blood lactate is considered significant based on the College of American Pathologists instrument peer-group standards. CONCLUSIONS: Considering that a change in whole blood lactate concentration of ≥ 0.4 mmol/L is unacceptable instrument peer-group variation as defined by the College of American Pathologists, ice is no longer needed to stabilize whole blood lactate specimens when the draw time to analyze time is < 45 min. Samples remain stable even at 90 min when left on ice.

Interstitial Lung Disease Associated With Crizotinib in Patients With Advanced Non-Small Cell Lung Cancer: Independent Review of Four PROFILE Trials.

INTRODUCTION: Interstitial lung disease (ILD) is a rare, but potentially serious, side effect associated with crizotinib, a tyrosine kinase inhibitor for anaplastic lymphoma kinase-positive (ALK+) advanced non-small cell lung cancer. Our objective was to determine the incidence and nature of ILD associated with crizotinib in 4 PROFILE trials (ClinicalTrials.gov identifiers, NCT00585195, NCT00932451, NCT00932893, and NCT01154140). MATERIALS AND METHODS: Grade ≥ 3 respiratory adverse events (AEs) and serious AEs (SAEs) and any grade AEs/SAEs reported as pneumonitis, ILD, or radiation pneumonitis in trials PROFILE 1001, PROFILE 1005, PROFILE 1007, and PROFILE 1014 were evaluated by an expert independent review committee that included a pulmonologist, medical oncologist, and radiologist. Events were designated as disease progression, de novo ILD possibly or probably related to crizotinib, exacerbation or recurrence of pre-existing ILD, concurrent illness, other toxicity not thought to be related to ILD, or inconclusive. RESULTS: The independent review committee evaluated 446 events (in 368 of 1669 patients who had received crizotinib therapy). They classified these events as follows: progressive disease, 77; de novo ILD, 20; pre-existing ILD, 3; concurrent illness, 9; other toxicities, 310; and inconclusive, 27. The incidence of de novo ILD was 1.2% overall, 1.3% in whites, and 1.2% overall in Asians, but greater at 3.7% in Japanese patients. The median onset of ILD from the initiation of crizotinib therapy was 23 days (range, 3-763 days). The mortality rate due to ILD was 50%. Survival was improved if crizotinib was discontinued on presentation of ILD (9 of 14 patients) compared with discontinued later or continued (1 of 6 patients). CONCLUSION: ILD associated with crizotinib, although rare, can occur at any time and requires close monitoring.

Nitrofurantoin compares favorably to recommended agents as empirical treatment of uncomplicated urinary tract infections in a decision and cost analysis.

OBJECTIVE: To analyze the costs of nitrofurantoin use compared to those of other antibiotics recommended for treatment of uncomplicated urinary tract infection (UTI). PATIENTS AND METHODS: We used a decision analysis model to perform cost-minimization and sensitivity analyses to determine the level of trimethoprim-sulfamethoxazole (TMP-SMX) and fluoroquinolone resistance that would favor the use of nitrofurantoin as a first-line empirical treatment of uncomplicated UTIs. The model used a program perspective to evaluate costs. RESULTS: Nitrofurantoin was cost-minimizing when the prevalence of fluoroquinolone resistance exceeded 12% among uropathogens or the prevalence of TMP-SMX resistance exceeded 17%. On 2-way sensitivity analysis, variables that had a significant impact on our cost-minimization threshold included cost of antibiotics and probability of clinical cure with antibiotics. CONCLUSION: From a payer perspective, nitrofurantoin appears to be a reasonable alternative to TMP-SMX and fluoroquinolones for empirical treatment of uncomplicated UTIs, especially given the current prevalence of antibiotic resistance among community uropathogens. On the basis of efficacy, cost, and low impact on promoting antimicrobial resistance, clinicians should consider nitrofurantoin as a reasonable alternative to TMP-SMX and fluoroquinolones for first-line therapy for uncomplicated UTIs.