Accuracy of determining hemoglobin level using occlusion spectroscopy in patients with severe gastrointestinal bleeding.

BACKGROUND: In patients presenting with severe hemorrhage, the authors conducted an equivalence trial that compared noninvasive occlusion spectroscopy and the capillary blood method to determine hemoglobin level. METHODS: This prospective observational study included patients admitted to their intensive care unit for gastrointestinal bleeding. A ring-shaped sensor, connected to a NBM-200MP (OrSense, Nes Ziona, Israel), was fitted onto the patient's thumb to intermittently measure hemoglobin (SotHb). During the first 24 h after admission, venous hemoglobin level, considered as the reference method, was determined at the laboratory every 8 h and was compared to SotHb and the capillary blood method. The primary endpoint was the proportion of inaccurate measurements, defined as greater than 15% difference compared with reference values or their unavailability for any technical reason. RESULTS: The study was scheduled to include 68 patients but was stopped prematurely after an interim analysis of 34 patients. The proportion of inaccuracies revealed that SotHb could not be considered equivalent to the capillary blood method (47% [95% CI, 43-51] and 24% [95% CI, 20-28]). Considering venous hemoglobin level as a reference method, the mean biases for SotHb (n = 133) and the capillary blood method (n = 135) were, respectively, -0.4 ± 2.0 and 0.8 ± 1.2 g/dl (P < 0.05). SotHb was associated with an increased incidence of failed transfusion. The inaccuracy of SotHb tended to be increased in patients receiving vasopressor agents. CONCLUSIONS: Noninvasive determination of hemoglobin level based on occlusion spectroscopy lacks accuracy in patients presenting with severe gastrointestinal bleeding and cannot be considered equivalent to the capillary-based method. This inaccuracy seems to be moderately influenced by the infusion of vasopressor agents.

How is norepinephrine used in intensive care? A field study.

OBJECTIVE: To assess how norepinephrine (NE), an emergency treatment of cardiovascular collapse, is used in intensive care. METHODS: Nurses and physicians of 14 intensive care units of the Bordeaux University Hospital were given questionnaires on the way they say they use NE and on actual NE treatment of patients. RESULTS: The clinical monitoring parameters cited were blood pressure, heart rate and hourly urine flow. Only 25% of the prescribers indicated the systematic use of hemodynamic monitoring. All the prescribers indicated they adapted the treatment to clinical objectives and blood pressure, and 77.5% to hourly urine flow. Initial NE concentrations ranged from 0.5 to 2 mg/ml, diluted in saline or dextrose. Initial prescribed dose ranged from 0.1 to 1 microg/kg/min. Large differences were observed between services and even within units. CONCLUSION: These data clearly show the need for recommendations regarding the use of norepinephrine.

Mass transfer, clearance and plasma concentration of procalcitonin during continuous venovenous hemofiltration in patients with septic shock and acute oliguric renal failure.

OBJECTIVES: To measure the mass transfer and clearance of procalcitonin (PCT) in patients with septic shock during continuous venovenous hemofiltration (CVVH), and to assess the mechanisms of elimination of PCT. SETTING: The medical department of intensive care. DESIGN: A prospective, observational study. PATIENTS: Thirteen critically ill patients with septic shock and oliguric acute renal failure requiring continuous venovenous postdilution hemofiltration with a high-flux membrane (AN69 or polyamide) and a 'conventional' substitution volume (< 2.5 l/hour). MEASUREMENTS AND MAIN RESULTS: PCT was measured with the Lumitest PCT Brahms(R) in the prefilter and postfilter plasma, in the ultrafiltrate at the beginning of CVVH (T0) and 15 min (T15'), 60 min (T60') and 6 hours (T6h) after setup of CVVH, and in the prefilter every 24 hours during 4 days. Mass transfer was determined and the clearance and the sieving coefficient were calculated according to the mass conservation principle. Plasma and ultrafiltrate clearances, respectively, at T15', T60' and T6h were 37 +/- 8.6 ml/min (not significant) and 1.8 +/- 1.7 ml/min (P < 0.01), 34.7 +/- 4.1 ml/min (not significant) and 2.3 +/- 1.8 ml/min (P < 0.01), and 31.5 +/- 7 ml/min (not significant) and 5 +/- 2.3 ml/min (P < 0.01). The sieving coefficient significantly increased from 0.07 at T15' to 0.19 at T6h, with no difference according to the nature of the membrane. PCT plasma levels were not significantly modified during the course of CCVH. CONCLUSIONS: We conclude that PCT is removed from the plasma of patients with septic shock during CCVH. Most of the mass is eliminated by convective flow, but adsorption also contributes to elimination during the first hours of CVVH. The effect of PCT removal with a conventional CVVH substitution fluid rate (<2.5 l/hour) on PCT plasma concentration seems to be limited, and PCT remains a useful diagnostic marker in these septic patients. The impact of high-volume hemofiltration on the PCT clearance, the mass transfer and the plasma concentration should be evaluated in further studies.