Struvite (MgNH4PO4.6H2O) solubility and its application to a piggery effluent problem

Struvite (MgNH4P04• 6H20) solution chemistry was studied in order to understand a struvite scaling problem which exists in the pipe network of a series of 4 effluent lagoons at a piggery. Struvite deposits frequently occur in piping from the final effluent pond intended for irrigation purposes, causing severe scaling of the pipe, making irrigation or other end uses of the effluent impossible. The conditional solubility constant (P. = SMg .SNH3-N•SPO.-P, equilibrium S values (M) was determined over the range of pH values (6.8-8.5) and solution concentrations of Mg, NHa-N and P04-P close to field conditions, and at a temperature of 30°C. A comparison of field and laboratory data indicates struvite precipitates from the second lagoon onwards. The solubility data obtained also indicate potential for precipitation as a method of nutrient removal from wastewaters

Combining quick Sequential Organ Failure Assessment with plasma lactate concentration is comparable to standard Sequential Organ Failure Assessment score in predicting mortality of patients with and without suspected infection

Purpose We sought to determine whether quick Sequential Organ Failure Assessment (qSOFA) score can be used to predict mortality of patients without suspected infection. Materials and methods Using prospectively collected data within the first hour of intensive care unit admission, the predictive ability of qSOFA was compared with the Simplified Acute Physiology Score III, Admission Mortality Prediction Model III, Acute Physiology and Chronic Health Evaluation II model, and standard (full-version) SOFA score using area under the receiver operating characteristic (AUROC) curve and Brier score. Results Of the 2322 patients included, 279 (12.0%) died after intensive care unit admission. The qSOFA score had a modest ability to predict mortality of all critically ill patients (AUROC, 0.672; 95% confidence interval [CI], 0.638-0.707; Brier score 0.099) including the noninfected patients (AUROC, 0.685; 95% CI, 0.637-0.732; Brier score 0.081). The overall predictive ability and calibration of the qSOFA was comparable to other prognostic scores. Combining qSOFA score with lactate concentrations further enhanced its predictive ability (AUROC, 0.730; 95% CI, 0.694-0.765; Brier score 0.097), comparable to the standard SOFA score. Conclusions The qSOFA score had a modest ability to predict mortality of both septic and nonseptic patients; combining qSOFA with plasma lactate had a predictive ability comparable to the standard SOFA score

Aspirin resistance significantly influences clinical and economic burden in cardiac surgery patients (Reply)

Reply to Letter to Edito

Use of viscoelastic tests to predict clinical thromboembolic events: A systematic review and meta-analysis

We aimed to assess whether whole-blood viscoelastic tests are useful to identify patients who are hypercoagulable and at increased risk of thromboembolism. Two investigators independently analyzed studies in the MEDLINE, EMBASE, and Cochrane controlled trial register databases to determine the ability of viscoelastic tests to identify a hypercoagulable state that is predictive of objectively proven thromboembolic events. Forty-one eligible studies, including 10,818 patients, were identified and subject to meta-analysis. The majority of the studies (n = 36, 88%) used the maximum clot strength to identify a hypercoagulable state which had a moderate ability to differentiate between patients who developed thromboembolic events and those who did not (area under the summary receiver operating characteristic [sROC] curve = 0.70, 95% confidence interval [CI]: 0.65-0.75). The pooled sensitivity, specificity, and diagnostic odds ratio to predict thromboembolism were 56% (95%CI: 44-67), 76% (95%CI: 67-83), and 3.6 (95%CI: 2.6-4.9), respectively. The predictive performance did not vary substantially between patient populations, and publication bias was not observed. Current evidence suggests that whole-blood viscoelastic tests have a moderate ability to identify a variety of patient populations with an increased risk of thromboembolic events and can be considered as a useful adjunct to clinical judgment to stratify a patient's risk of developing thromboembolism

Procalcitonin concentrations as a predictor of unexpected readmission and mortality after intensive care unit discharge: A retrospective cohort study

Procalcitonin (PCT) has been used to guide treatment in critically ill patients with sepsis, but whether PCT at intensive care unit (ICU) discharge can stratify risks of post-ICU readmission or mortality is unknown. This cohort study compared the ability of PCT to C-reactive protein (CRP) in predicting unexpected adverse post-ICU events. Of the 1877 patients admitted to the multidisciplinary ICU between 1 April 2012 and 31 March 2014, 1653 (88.1%) were discharged without treatment limitations. A total of 71 (4.3%) were readmitted and 18 patients (1%) died unexpectedly after ICU discharge during the same hospitalization. Both PCT (0.6 vs. 0.4ug/L, p=0.002) and a high CRP concentration > 100mg/L (58% vs. 41%, p=0.004) at ICU discharge were associated with an increased risk of adverse post-ICU events in the univariate analyses, however the ability of PCT to discriminate between patients with and without adverse post-ICU outcomes was limited (area under the receiver-operating-characteristic curve = 0.61, 95% confidence interval [CI]: 0.55-0.66). In the multivariable analysis, only a high CRP concentration (odds ratio 1.92, 95%CI: 1.12-3.11; p=0.008) was associated with an increased adverse post-ICU events. Elevated PCT concentration at ICU discharge was inadequate in its predictive ability to guide ICU discharge

Predicting contrast-induced nephropathy after CT pulmonary angiography in the critically ill: a retrospective cohort study

Background It is uncertain whether we can predict contrast-induced nephropathy (CIN) after CT pulmonary angiography (CTPA). This study compared the ability of a validated CIN prediction score with the Pulmonary Embolism Severity Index (PESI) in predicting CIN after CTPA. Methods This cohort study involved critically ill adult patients who required a CTPA to exclude acute pulmonary embolism (PE). Patients with end-stage renal failure requiring dialysis were excluded. CIN was defined as an elevation in plasma creatinine concentrations > 44.2μmol/l (or 0.5 mg/dl) within 48 h after CTPA. Results Of the 137 patients included, 77 (51%) were hypotensive, 54 (39%) required inotropic support, and 68 (50%) were mechanically ventilated prior to the CTPA. Acute PE was confirmed in 21 patients (15%) with 14 (10%) being bilateral. CIN occurred in 56 patients (41%) with 35 (26%) required dialysis subsequent to CTPA. The CIN prediction score had a good ability to discriminate between patients with and without developing CIN (Area under the receiver-operating-characteristic (AUROC) curve 0.864, 95% confidence interval [CI] 0.795–0.916) and requiring subsequent dialysis (AUROC 0.897, 95% CI 0.833–0.942) and was better than the PESI in predicting both outcomes (AUROC 0.731, 95% CI 0.649–0.804 and 0.775, 95% CI 0.696–0.842, respectively). A CIN risk score > 10 and 12 had an 82.1 and 85.7% sensitivity and 81.5 and 78.4% specificity to predict subsequent CIN and dialysis, respectively. The CIN prediction model tended to underestimate the observed risks of dialysis, but this was improved after recalibrating the slope and intercept of the original prediction equation. Conclusions The CIN prediction score had a good ability to discriminate between critically ill patients with and without developing CIN after CTPA. Used together for critically ill patients with suspected acute PE, the CIN prediction score and PESI may be useful to inform clinicians when the benefits of a CTPA scan will outweigh its potential harms

Urinary potassium excretion and its association with acute kidney injury in the intensive care unit

Purpose Using urinary indices as a quick bedside test to assist management of oliguria and acute kidney injury (AKI) has long been sought. This study assessed whether urinary potassium excretion is related to simultaneously calculated creatinine clearance (CrCl) and can predict AKI in the critically ill. Materials and methods In this prospective cohort study, the correlation between 2-h urinary potassium excretion and simultaneously calculated CrCl of 61 critically ill patients was assessed by Pearson's correlation coefficient, and their ability to predict AKI (≥stage 1 KDIGO) in the subsequent 7 days was assessed by area under the receiver-operating-characteristic (AUROC) curve. Results Urinary potassium excretion (median 6.2 mmol, range 0.8–24.3) correlated linearly with CrCl (correlation coefficient: 0.58, 95% confidence interval [CI] 0.38–0.72; p = 0.001), and had a moderate ability to predict subsequent AKI (n = 19 [31%]; AUROC 0.747, 95%CI 0.620–0.850; p = 0.001), especially in patients without prior exposure to furosemide within 24-h (correlation coefficient 0.61, 95%CI 0.41–0.76; AUROC 0.789, 95%CI 0.654–0.890; p = 0.001, respectively). Conclusions Urinary potassium excretion correlates with CrCl and predicts AKI in the critically ill without recent furosemide exposure. Given 2-hour urinary potassium excretion can be measured easily, its potential as a marker of renal function deserves further study

Safety and efficacy of intravenous iron therapy in reducing requirement for allogeneic blood transfusion: systematic review and meta-analysis of randomised clinical trials

Objectives To evaluate the efficacy and safety of intravenous iron, focusing primarily on its effects on haemoglobin, requirement for transfusion, and risk of infection. Design Systematic review and meta-analysis of randomised controlled trials investigating the safety and efficacy of intravenous iron therapy. Data sources Randomised controlled trials from Medline, Embase, and the Cochrane Central Register of Controlled Trials from 1966 to June 2013, with no language restrictions. Eligibility criteria for selecting studies Eligible trials were randomised controlled trials of intravenous iron compared with either no iron or oral iron. Crossover and observational studies were excluded. Main outcome measures Change in haemoglobin concentration and risk of allogeneic red blood cell transfusion (efficacy) and risk of infection (safety). Results Of the 75 trials meeting the inclusion criteria, 72 studies including 10 605 patients provided quantitative outcome data for meta-analysis. Intravenous iron was associated with an increase in haemoglobin concentration (standardised mean difference 6.5 g/L, 95% confidence interval 5.1 g/L to 7.9 g/L) and a reduced risk of requirement for red blood cell transfusion (risk ratio 0.74, 95% confidence interval 0.62 to 0.88), especially when intravenous iron was used with erythroid stimulating agents (ESAs) or in patients with a lower baseline plasma ferritin concentration. There were no significant interactions between the efficacy of intravenous iron and type or dose administered. Intravenous iron was, however, associated with a significant increase in risk of infection (relative risk 1.33, 95% confidence interval 1.10 to 1.64) compared with oral or no iron supplementation. The results remained similar when only high quality trials were analysed. Conclusions Intravenous iron therapy is effective in increasing haemoglobin concentration and reducing the risk of allogeneic red blood cell transfusion and could have broad applicability to a range of acute care settings. This potential benefit is counterbalanced by a potential increased risk of infection