Evaluation of a calcium, magnesium and phosphate clinical ordering tool in the emergency department.

OBJECTIVE: We developed a clinical tool comprising patient risk factors for having an abnormal calcium (Ca), magnesium (Mg) or phosphate (PO4) level. We hypothesized that patients without a risk factor do not require testing. This study examined the tool's potential utility for rationalizing Ca, Mg and PO4 ordering in the emergency department (ED). METHODS: We undertook a retrospective observational study in a single metropolitan ED. Patients aged 18 years or more who presented between July and December 2019 were included if they had a Ca, Mg or PO4 test during their ED stay. Demographic and clinical data, including the presence of risk factors, were extracted from the medical record. The primary outcome was a clinically significant abnormal Ca, Mg or PO4 level (>0.2 mmol/l above or below the laboratory reference range). RESULTS: Calcium, Mg and PO4 levels were measured on 1426, 1296 and 1099 patients, respectively. The positive and negative predictive values and likelihood ratios of the tool identifying a patient with a Ca level > 0.2 mmol/l outside the range were 0.05, 0.99, 1.59 and 0.41, respectively. The values for Mg were 0.02, 1.00, 1.44 and 0.35 and those for PO4 were 0.15, 0.93, 1.38 and 0.57, respectively. The majority of patients not identified as having an abnormal level did not receive electrolyte correction treatment. Application of the tool would have resulted in a 35.8% cost reduction. CONCLUSION: The tool failed to predict a very small proportion of patients (approximately 1%) with an abnormal Ca or Mg level and for whom it would have been desirable to have these levels measured. It may help rationalize Ca and Mg ordering and reduce laboratory costs.

Utility of calcium, magnesium and phosphate testing in the emergency department.

OBJECTIVE: To determine how frequently calcium (Ca), magnesium (Mg) and phosphate (PO4 ) tests change ED patient management. METHODS: We undertook a retrospective observational study in an Australian tertiary referral ED. We enrolled adult patients (aged ≥18 years) who presented between 1 January and 30 June 2017 and who had a serum Ca, Mg or PO4 test ordered and completed during their ED stay. Patient symptoms, medical history, electrolyte levels and ED management changes were extracted from the electronic medical record. RESULTS: Of the 33 120 adults presented during the study period, 1716 (5.2%, 95% confidence interval [CI] 5.0-5.4) had at least one Ca, Mg or PO4 test completed in the ED. This included 4776 individual electrolyte tests, of which 776 (16.2%, 95% CI 15.2-17.3) were abnormal. Fifty-six (7.2% [95% CI 5.5-9.3] of patients with abnormal tests, 1.2% [95% CI 0.9-1.5] of all tests) tests were associated with a change in ED management. Twenty-six out of 1683 (1.5%) Ca levels were low with six (23.1%) management changes; 203 (12.1%) were high with 10 (4.9%) management changes. One hundred and twenty-eight out of 1579 (8.1%) Mg levels were low with 33 (25.8%) management changes; 30 (1.9%) were high with no management changes. Two hundred and twenty-five out of 1514 (14.9%) PO4 levels were low with six (2.7%) management changes; 164 (10.8%) were high with one (0.6%) management change. Fifty (2.9%) patients had management changes despite normal electrolyte levels. CONCLUSION: Ca, Mg and PO4 testing is common. However, the yield of clinically significant abnormal levels is low and patient management is rarely changed. Testing of these electrolytes needs to be rationalised.

Risk variables associated with abnormal calcium, magnesium and phosphate levels among emergency department patients.

OBJECTIVE: The utility of calcium, magnesium and phosphate measurement in the ED is limited. We aimed to determine clinical risk variables for abnormal levels of these electrolytes in order to inform the development of an ordering guideline. METHODS: We performed a retrospective, observational study of patients who presented to a tertiary referral ED between January and June 2017. Adult patients who had serum calcium, magnesium or phosphate tests completed during their ED stay were included. Presenting symptoms and signs, comorbidities, medication use and laboratory values were extracted from the medical record. Patients with missing data items were excluded. Logistic regression models determined clinical risk variables associated with low and high levels of each electrolyte. RESULTS: A total of 33 120 adults presented during the study period. Of the 1679 calcium, 1576 magnesium and 1511 phosphate tests, 228 (13.6%), 158 (10.0%) and 387 (25.6%) were abnormal, respectively. Significant risk variables (P < 0.05) for abnormal levels were: hypocalcaemia - vomiting, perioral numbness, hand/foot spasm, calcium and phosphate supplements and chemotherapy (odds ratio [OR] range 5.9-17.3); hypercalcaemia - female sex, vomiting, polyuria, confusion, hyperparathyroidism, cancer and type 1 diabetes (OR range 2.3-9.7); hypomagnesemia - female sex, proton pump inhibitor use, tacrolimus use, alcohol abuse and type 2 diabetes (OR range 2.2-13.1); hypermagnesemia - lethargy, thiazide use and chronic kidney disease (OR range 4.3-4.5); hypophosphatemia - nausea, seizure and glucocorticoid use (OR range 1.7-2.1); and hyperphosphataemia - polyuria, diuretics and chronic kidney disease (OR range 1.9-5.0). CONCLUSION: A range of demographic, comorbid, medication and clinical variables are associated with abnormal calcium, magnesium and phosphate levels. These findings will inform the development of clinical guidelines to rationalise calcium, magnesium and phosphate testing. Justification may be required for testing patients with no risk variables.

Carbon monoxide and cyanide poisoning in fire related deaths in Victoria, Australia.

OBJECTIVE: This study was undertaken to examine the association of hydrogen cyanide and carboxyhaemoglobin in victims of fire related deaths in Australia. The secondary aim was to document demographic data about Australian fire related deaths. METHODS: An observational retrospective study was undertaken of autopsy reports from the Victorian Institute of Forensic Medicine. Reports of fire related deaths were electronically searched using the terms burns, "smoke" or "fire" as a cause of death in the calender years 1992 to 1998. Data on the circumstances of the fire and results of toxicological screening were obtained on 178 persons. Additional whole blood cyanide levels were determined if blood samples were available in storage. Demographics of the victims were analysed, as well as the relationship between carboxyhaemoglobin and whole blood cyanide levels. RESULTS: Most (82%) of the victims died at the scene, whilst 32 victims died after a period of hospitalisation (hours to weeks). Suicide as a result of self-immolation was the reported cause of death in 32 cases. Most of the fires were in houses (114) and cars (29). The blood ethanol level was zero in 112 cases; the remaining cases (53) had a mean level of 0.17%. Other central nervous system (CNS) depressants were recorded in 49 of the 134 cases that received a complete toxicological screen. Carboxyhaemoglobin levels were measured in only 154 of 178 cases. The carboxyhaemoglobin level was zero in 43 cases. The remaining cases (111) had a mean level of 40%; with 44 cases having a level greater than 50%, a level considered to be potentially lethal. Whole blood hydrogen cyanide levels were measured in only 138 of 178 cases. The hydrogen cyanide level was zero in 52 cases. The remaining cases (86) had a mean level of 1.65 mg/L; with 11 cases having a level greater than 3.0 mg/L (potentially fatal). Blood ethanol levels were significantly correlated with both carboxyhaemoglobin (R = 0.22, P < 0.01) and cyanide (R = 0.36, P < 0.001). In addition, a significant correlation (r = 0.34) between carboxyhaemoglobin and hydrogen cyanide levels was noted. CONCLUSIONS: This study showed a correlation between elevated blood ethanol and whole blood cyanide levels (r = 0.36, p < 0.001) and between elevated carboxyhaemoglobin and hydrogen cyanide levels (r = 0.34). Although the mean cyanide level was 1.3 mg/L (above the level some consider potentially toxic) in those cases with a carboxyhaemoglobin level of greater than 10%, there is insufficient data to permit recommendations for clinical care. Further studies are required on those victims that reach hospital alive.

Multidisciplinary assessment at triage: a new way forward.

OBJECTIVE: To evaluate a dual doctor and nurse triage system at a tertiary referral hospital. METHODS: Data were compared between periods of multidisciplinary triage and periods of standard triage. Data comparison was also made between rostered multidisciplinary triage shifts and non-multidisciplinary triage shifts. Staff satisfaction with the process was assessed. RESULTS: The percentage of patients seen within Australasian Triage Scale performance indicator thresholds increased from 75% to 81% in Category 2 patients (P = 0.12) and 56% to 78% in Category 3 patients (P < 0.0001). There was a reduction of 50% in the number of patients who left prior to being seen by a doctor (P = 0.024). Surveys showed high staff satisfaction with the process. CONCLUSIONS: We feel that multidisciplinary triage performs a useful function in our department enabling us to reduce waiting times. The process is widely accepted amongst the staff and it ensures a senior doctor assesses most patients. It reduces the number of patients leaving prior to being seen by a doctor and it provides one way of getting around access block and a physically small department.