Continuous intra-arterial blood glucose monitoring using quenched fluorescence sensing in intensive care patients after cardiac surgery: phase II of a product development study.

PURPOSE: Variations in blood glucose (BG), hyperglycaemia and hypoglycaemia are associated with adverse clinical outcomes in intensive care unit patients. Continuous glucose monitoring (CGM) offers the potential to improve BG control, leading to improved patient outcomes. In our product development study, we determined the safety and performance of the GluCath Intravascular CGM System for up to 48 hours in 20 patients admitted to the ICU after cardiac surgery. METHODS: The GluCath system uses a quenched chemical fluorescence mechanism to optically measure glucose in blood. After undergoing elective cardiac surgery, 20 patients had a GluCath sensor inserted through a preexisting radial artery (RA) catheter, and BG was monitored for up to 48 hours. Qualitative measures included effects on patient care, blood pressure monitoring, and ease of blood sampling through the arterial catheter. Safety assessment of the sensor involved ultrasound (US) monitoring for intra-arterial thrombi. Quantitative measures were the accuracy of the sensor in comparison with the reference analyser, and the proportion of paired BG measurements that were compliant with the ISO15197:2003 and CLSI POCT 12-A3 accuracy reference standards. BG was managed according to usual protocols. RESULTS: Twenty sensors were successfully deployed through pre-existing RA catheters and stayed in the RA of the 20 patients for between 6 and 48 hours, with a median time of 45.0 hours (interquartile range, 42.0-47.3 hours). Sixteen of the inserted sensors (80%) remained in situ for more than 40 hours. Three catheters were removed due to clinically significant sampling difficulty or waveform dampening. Two patients had US evidence of a thrombus; in neither patient was the sensor removed early, and there were no significant sequelae or adverse effects detected. For the 758 paired measurements available for performance analysis, reference BG values ranged between 5.3 mmol/L and 12.8 mmol/L. Of the 758 paired sensor measurements, 735 (97.0%) met the ISO15197:2003 criteria (within 20% of a reference measurement when BG is ≥ 4.2 mmol/L [75 mg/dL]), and 648 (85.5%) met the CLSI POCT 12-A3 criteria (within 12.5% of a reference measurement when the BG level is ≥ 5.6 mmol/L [100mg/dL] and within 0.67 mmol/L [12 mg/dL] when the BG level is < 5.6mmol/L [100 mg/dL]). The aggregate mean absolute relative difference (MARD) between the sensor and the reference BG was 6.4%, with individual sensor MARDs ranging from 3.6% to 12.4%. CONCLUSIONS: The GluCath system, using quenched fluorescence sensing, was safe and showed acceptable accuracy when deployed for up to 48 hours in ICU patients after elective cardiac surgery.

Use of an Intravascular Fluorescent Continuous Glucose Sensor in ICU Patients.

BACKGROUND: Hyperglycemia and hypoglycemia are associated with adverse clinical outcomes in intensive care patients. In product development studies at 4 ICUs, the safety and performance of an intravascular continuous glucose monitoring (IV-CGM) system was evaluated in 70 postsurgical patients. METHODS: The GluCath System (GluMetrics, Inc) used a quenched chemical fluorescence mechanism to optically measure blood glucose when deployed via a radial artery catheter or directly into a peripheral vein. Periodic ultrasound assessed blood flow and thrombus formation. Patient glucose levels were managed according to the standard of care and existing protocols at each site. Reference blood samples were acquired hourly and compared against prospectively calibrated sensor results. RESULTS: In all, 63 arterial sensors and 9 venous sensors were deployed in 70 patients. Arterial sensors did not interfere with invasive blood pressure monitoring, sampling or other aspects of patient care. A majority of venous sensors (66%) exhibited thrombus on ultrasound. In all, 89.4% (1383/1547) of arterial and 72.2% (182/252) of venous measurements met ISO15197:2003 criteria (within 20%), and 72.7% (1124/1547) of arterial and 56.3% (142/252) of venous measurements met CLSI POCT 12-A3 criteria (within 12.5%). The aggregate mean absolute relative difference (MARD) between the sensors and the reference was 9.6% for arterial and 14.2% for venous sensors. CONCLUSIONS: The GluCath System exhibited acceptable accuracy when deployed in a radial artery for up to 48 hours in ICU patients after elective cardiac surgery. Accuracy of venous deployment was substantially lower with significant rates of intravascular thrombus observed using ultrasound.

Continuous intra-arterial blood glucose monitoring using quenched fluorescence sensing: a product development study.

BACKGROUND: Continuous glucose monitoring (CGM) has the potential to improve the management of blood glucose (BG) and so improve patient safety and outcomes in intensive care units. The GluCath Intravascular CGM (IV-CGM) System (GluMetrics) uses a novel quenched chemical fluorescence sensing mechanism to measure BG. OBJECTIVE: We aimed to assess the safety and performance of the GluCath IV-CGM for a 24-hour period in 20 patients admitted to an ICU after cardiac surgery. METHODS: Heparin-bonded sensors were deployed via a standard 20-gauge radial arterial catheter inserted for routine care in 21 participants after cardiac surgery. Sensors were inserted shortly after ICU admission and BG was monitored for up to 24 hours. After an in vivo calibration, the system recorded BG every minute. Ultrasound examinations checked for sensor position and the presence of thrombus. Outcome measures were qualitative (ease of use, interference with clinical care, blood pressure monitoring and blood sampling) and quantitative (accuracy in comparison with hourly measurements from a reference analyser). BG was managed according to usual protocols. RESULTS: Of 21 sensors deployed, one failed and one was malpositioned due to operator error. A total of 488 reference samples were collected, with BG concentrations ranging from 4.7mmol/L to 13.4 mmol/L. Calibration samples, samples from the malpositioned sensor and six samples affected by technical errors were excluded. Of 437 paired sensor and reference measurements used to assess accuracy, 353 (80.8%) met International Organization for Standardization standard 15197: 2003 criteria (within 20% of reference when BG≥4.2mmol/L). The aggregate mean absolute relative difference (MARD) was 13.0%, with the MARD for individual sensors ranging from 4.7% to 33.5%. Preremoval ultrasounds detected clinically insignificant intravascular thrombus in five of 21 patients (23.8%). No sensor interfered with clinical care, haemodynamic monitoring or blood sampling. There were no device related serious adverse events. CONCLUSIONS: In this product development study, use of the GluCath system for 24 hours after cardiac surgery had no adverse effect on haemodynamic monitoring, arterial blood sampling or clinical care. Overall accuracy was acceptable in the context of the first phase of a product development study.

Target Temperature Management after out-of-hospital cardiac arrest--a randomized, parallel-group, assessor-blinded clinical trial--rationale and design.

BACKGROUND: Experimental animal studies and previous randomized trials suggest an improvement in mortality and neurologic function with induced hypothermia after cardiac arrest. International guidelines advocate the use of a target temperature management of 32°C to 34°C for 12 to 24 hours after resuscitation from out-of-hospital cardiac arrest. A systematic review indicates that the evidence for recommending this intervention is inconclusive, and the GRADE level of evidence is low. Previous trials were small, with high risk of bias, evaluated select populations, and did not treat hyperthermia in the control groups. The optimal target temperature management strategy is not known. METHODS: The TTM trial is an investigator-initiated, international, randomized, parallel-group, and assessor-blinded clinical trial designed to enroll at least 850 adult, unconscious patients resuscitated after out-of-hospital cardiac arrest of a presumed cardiac cause. The patients will be randomized to a target temperature management of either 33°C or 36°C after return of spontaneous circulation. In both groups, the intervention will last 36 hours. The primary outcome is all-cause mortality at maximal follow-up. The main secondary outcomes are the composite outcome of all-cause mortality and poor neurologic function (cerebral performance categories 3 and 4) at hospital discharge and at 180 days, cognitive status and quality of life at 180 days, assessment of safety and harm. DISCUSSION: The TTM trial will investigate potential benefit and harm of 2 target temperature strategies, both avoiding hyperthermia in a large proportion of the out-of-hospital cardiac arrest population.

Alcohol and substance use by patients with psychosis presenting to an emergency department: changing patterns.

OBJECTIVES: The aim of this study was to determine the incidence of alcohol and other substance use in patients presenting to an emergency department with acute psychiatric illnesses and to clarify the role of urine drug screens. METHOD: This was an unblinded prospective (observational) cohort study incorporating retrospective review of patient medical records, history of alcohol and substance use, results of urine drug screens and blood alcohol concentrations. RESULTS: Of 196 acute psychotic patients, 104 were diagnosed with schizophrenia and 92 with "other psychosis". Results of urine drug screens were consistent with self-reported use of substances and only identified an additional 5% of substance users. Cannabis was the commonest illicit substance used by both groups of patients, followed by psychostimulants, mainly amphetamines. Younger males were more likely to use psychostimulants and to present with violence. CONCLUSIONS: Patients with co-existing mental health problems and substance use present a major problem for our emergency departments. Cannabis was the most common substance used. Youth, male gender and psychostimulant use are associated with violent presentations. A comprehensive history of alcohol and substance use is important to implement appropriate dual diagnosis treatment. Urine drug screening is recommended for patients who do not admit to substance use.

Field triage to primary angioplasty combined with emergency department bypass reduces treatment delays and is associated with improved outcome.

AIMS: We investigated the net benefit in the outcome of reducing treatment delay through field triage and emergency department (ED) bypass in patients with ST-elevation myocardial infarction (STEMI) treated with primary angioplasty. METHODS AND RESULTS: In a prospective registry study, consecutive patients with suspected STEMI were assigned to: (i) pre-hospital ECG and triage or (ii) ECG and triage at the closest ED, solely based on ambulance availability. Four district hospitals and one regional heart centre serviced the 890,000 population metropolitan area and primary angioplasty was the only reperfusion strategy employed. Baseline characteristics were similar in STEMI patients triaged in the field (108) and the EDs (193). Symptom onset to balloon times: 154 [inter-quartile range (IQR) 120-233) vs. 249 (IQR 184-405) min (P<0.001) and peak creatine kinase in early presenters (<2 h): 1435 (95 %CI: 904-1966) U/L vs. 2320 (95% CI: 1881-2762) U/L (P=0.009) were lower in field- than in ED-triaged patients. Mortality in the PCI treated were 1.1 and 8.2% [P=0.025, RR 0.14 (95% CI: 0.01-1.08)] and overall mortality were 1.9 and 7.3% [P=0.046, RR 0.26 (95% CI: 0.05-1.11)]. CONCLUSION: Field-triage and ED bypass were feasible means of reducing treatment delay in patients with suspected STEMI and resulted in smaller infarct size in early presenters and a trend towards a reduction in mortality.

The accuracy of focused assessment with sonography in trauma (FAST) in blunt trauma patients: experience of an Australian major trauma service.

UNLABELLED: Focused assessment with sonography for trauma (FAST) is a method for detecting haemoperitoneum in trauma patients on initial assessment in the Emergency Department. The aim of this paper is to present an Australian trauma centre's experience with FAST as a tool to screen for intraabdominal free fluid in patient's sustaining blunt truncal trauma. METHOD: Over a 63-month period, FAST scans were prospectively studied and compared with findings from a gold-standard investigation, either computed tomography (CT) or laparotomy. RESULTS: 463 FAST results were collected prospectively from 463 patients. 53 scans were excluded due to lack of a corresponding confirmatory gold-standard test. Overall sensitivity, specificity, positive and negative predictive values for FAST in detecting free fluid were 78%, 97%, 91%, 93%, respectively. Analysis of the credentialed operators demonstrated an improvement in accuracy (sensitivity 80%, specificity 100%, positive predictive value 100%, negative predictive value 94%). These findings are comparable with documented international experience. CONCLUSION: The study demonstrates that the use of non-radiologist performed FAST in the detection of free fluid is safe and accurate within an Australian Trauma Centre.

Trauma bypass in south-eastern Sydney: an 8-year review.

OBJECTIVE: The New South Wales (NSW) Health Department and the Ambulance Service of NSW introduced a trauma bypass system in Sydney on 29 March 1992. This study aims to review the outcomes of trauma bypass patients brought to St George Hospital, a major trauma service in south-eastern Sydney, and to assess the performance of the current prehospital trauma triage protocol. METHODS: The St George Hospital Department of Trauma Services prospectively collected data on all trauma bypass patients for the 8-year period from 29 March 1992 to 29 March 2000. RESULTS: A total of 1990 patients were brought to hospital on trauma bypass. The average age was 32 years, 70% were men and 66% were from road traffic accidents. The positive predictive value of the prehospital triage tool for serious injury (Injury Severity Score [ISS] > 15) was 18.6% (95% CI 16.9-20.4). This is well below the benchmark previously established by the NSW Health Department Trauma System Advisory Committee. For all trauma bypass patients, 33.8% (95% CI 31.7-35.9) were discharged home from the ED. The overall death rate was 2.5% (95% CI 1.9-3.3). CONCLUSIONS: According to the proposed benchmark, current prehospital trauma triage guidelines are underperforming. This suggests that a review of the benchmarks of current local trauma systems and of the trauma triage tool is required.