Point and trend accuracy of a continuous intravenous microdialysis-based glucose-monitoring device in critically ill patients: a prospective study.

BACKGROUND: Microdialysis is a well-established technology that can be used for continuous blood glucose monitoring. We determined point and trend accuracy, and reliability of a microdialysis-based continuous blood glucose-monitoring device (EIRUS(®)) in critically ill patients. METHODS: Prospective study involving patients with an expected intensive care unit stay of ≥48 h. Every 15 min, device readings were compared with blood glucose values measured in arterial blood during blocks of 8 h per day for a maximum of 3 days. The Clarke error grid, Bland-Altman plot, mean absolute relative difference and glucose prediction error analysis were used to express point accuracy and the rate error grid to express trend accuracy. Reliability testing included aspects of the device and the external sensor, and the special central venous catheter (CVC) with a semipermeable membrane for use with this device. RESULTS: We collected 594 paired values in 12 patients (65 [26-80; 8-97] (median [IQR; total range]) paired values per patient). Point accuracy: 93.6 % of paired values were in zone A of the Clarke error grid, 6.4 % were in zone B; bias was 4.1 mg/dL with an upper limit of agreement of 28.6 mg/dL and a lower level of agreement of -20.5 mg/dL in the Bland-Altman analysis; 93.6 % of the values ≥75 mg/dL were within 20 % of the reference values in the glucose prediction error analysis; the mean absolute relative difference was 7.5 %. Trend accuracy: 96.4 % of the paired values were in zone A, and 3.3 and 0.3 % were in zone B and zone C of the rate error grid. Reliability: out of 16 sensors, 4 had to be replaced prematurely; out of 12 CVCs, two malfunctioned (one after unintentional flushing by unsupervised nurses of the ports connected to the internal microdialysis chamber, causing rupture of the semipermeable membrane; one for an unknown reason). Device start-up time was 58 [56-67] min; availability of real-time data was 100 % of the connection time. CONCLUSIONS: In this study in critically ill patients who had no hypoglycemic episodes and a limited number of hyperglycemic excursions, point accuracy of the device was moderate to good. Trend accuracy was very good. The device had no downtimes, but 4 out of 16 external sensors and 2 out of 12 CVCs had practical problems.

Clinical prospective study of biochemical markers and evoked potentials for identifying adverse neurological outcome after thoracic and thoracoabdominal aortic aneurysm surgery.

BACKGROUND: Neurological deficit after repair of a thoracic or thoracoabdominal aortic aneurysm (TAA/TAAA) remains a devastating complication. The aim of our study was to investigate the clinical value of biochemical markers [S-100B, neurone-specific enolase (NSE) and lactate dehydrogenase (LD)], evoked potentials and their combinations for identifying adverse neurological outcome after TAA/TAAA surgery. METHODS: From 69 patients, cerebrospinal fluid and blood samples for biochemical analysis were drawn after the induction of anaesthesia, during the cross-clamp period, 5 min, 2, 4, 6, 8, and 19 h, respectively, after reperfusion. In addition, continuous perioperative recording of motor-evoked potentials after transcranial electrical stimulation (tcMEP) and somatosensory-evoked potentials was carried out. Furthermore, neurological examinations were performed. RESULTS: In patients with a defined decrease in lower extremity tcMEP during the cross-clamp period, we found that combinations of the serum concentrations of S-100B and tcMEP ratios at 4, 6, and 8 h after reperfusion had a positive and negative predictive value of 100% in predicting adverse neurological outcome after TAA/TAAA surgery. Furthermore, combinations of the serum concentrations of S-100B and NSE or LD at 19 h after reperfusion had both a positive and negative predictive value of 100% in identifying patients with adverse outcome after TAA/TAAA repair. CONCLUSIONS: TcMEP monitoring during TAA/TAAA surgery seems to be an effective but not completely sufficient guide in our protective multi-modality strategy. Combinations of the serum concentrations of S-100B and tcMEP ratios during the early reperfusion period might be associated with adverse neurological complications. Furthermore, biochemical markers could detect central nervous system injury on the first postoperative day and may have prognostic value.

Oxidative stress after lung resection therapy: A pilot study.

STUDY OBJECTIVES: To investigate whether oxidative stress occurs following lobectomy and pneumonectomy and to evaluate whether markers of oxidative stress might be of value in the assessment of the diagnosis, course, and prognosis of postoperative complications. DESIGN: A prospective study. SETTING: A specialized thoracic surgical unit in a large referral hospital. PATIENTS: Twenty-eight patients with lung carcinoma undergoing thoracotomy. MEASUREMENTS: Exhaled H(2)O(2) concentrations in breath condensate were measured by spectrophotometry, while malondialdehyde (MDA) levels in urine samples collected every 24 h were measured by reversed-phase, ion-pair high-performance liquid chromatography using ultraviolet detection. RESULTS: Our results show increased H(2)O(2) and MDA levels in lobectomy patients compared with pneumonectomy patients. A strong correlation was found between the levels of H(2)O(2) and MDA. CONCLUSION: The present data support the hypothesis that oxidative stress may occur following pulmonary resection.