Precision of a new bedside method for estimation of the circulating blood volume

Abstract

The present study is a theoretical and experimental evaluation of a modification of the carbon monoxide method for estimation of the circulating blood volume (CBV) with respect to the precision of the method. The CBV was determined from measurements of the CO-saturation of hemoglobin before and after ventilation with a gas mixture containing 20-50 ml of CO for a period of 10-15 min. A special Water's to and fro system was designed in order to avoid any leakage when measuring during intermittent positive pressure ventilation (IPPV). Blood samples were taken before and immediately after ventilation with the CO gas mixture. The amount of CO administered during each determination of CBV resulted in an increase in the CO saturation of hemoglobin of 2.1%-3.9%. A theoretical noise propagation analysis was performed by means of the Monte Carlo method. The analysis showed that a CO dose corresponding to an increase of less than 2% will result in an unacceptable coefficient of variation of repeated estimates. In the experimental study the coefficient of variation of repeated estimates of CBV was determined from duplicate measurements of CBV in nine healthy subjects and in nine intensive care patients. The coefficients of variation were 6.2% and 4.7% in healthy and diseased subjects, respectively. Furthermore, the day-to-day variation of the method with respect to the total amount of circulating hemoglobin (nHb) and CBV was determined from duplicate estimates separated by 24-48 h. In conclusion, determination of CBV can be performed with an amount of CO that gives rise to a harmless increase in the carboxyhemoglobin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Skin-prick blood samples are reliable for estimating Hb mass with the CO-dilution technique

“…Although CAP systematically overestimated Hb mass by 1.7% compared with VEN, the technical error of measurement (2.7%) compares favourably with previous reports for the venepuncture technique: 0.8% (Burge and Skinner 1995), 1.9% (Gore et al 1997), 2.5% (Fogh-Andersen et al 1990) and 5.1% (Christensen et al 1993). This level of reproducibility is quite acceptable for the majority of experimental circumstances and would for example be suited to longitudinal studies involving exposure to environmental stimuli that may alter Hb mass.…”

Plasma volume in acute hypoxia: comparison of a carbon monoxide rebreathing method and dye dilution with Evans' blue

“…The volume of CO administered was 50 ml at sea level and 60 ml at high altitude. Rebreathing time was 10 min to ensure that maximal COHb% had been reached (Fogh-Andersen et al 1990; Thomsen et al 1991;Christensen et al 1993;Burge and Skinner 1995).…”

“…Used in connection with the new generation of multiwave length spectrophotometers the carbon monoxide (CO) rebreathing method has been found to facilitate very accurate and precise measurements of blood and plasma volumes (Fogh-Andersen et al 1990;Thomsen et al 1991;Christensen et al 1993;Burge and Skinner 1995). The purpose of this study was to compare the volume of distribution of albumin (Evans' blue method, PV Evans' ) with measurements of plasma volume obtained by the CO rebreathing method (PV CO ) in normal subjects at sea level and again 24 h after a rapid, passive ascent to 4,350 m. Furthermore, the eect of acute hypoxaemia on TER Alb was measured.…”

Living high–training low: effect on erythropoiesis and aerobic performance in highly-trained swimmers

“…Red blood cell volume, blood volume and plasma volume were determined by a carbon monoxide rebreathing method (Circulating Blood Volume System, CBVMedical, Denmark) (Christensen et al 1993;Poulsen et al 1998). Briefly, after a 20-min resting period in a sitting position, the subjects breathed into a closed circuit, including a 2-l rebreathing bag, and a carbon dioxide absorber.…”

“…Hematocrit (Hct) was measured in triplicate by a microcentrifuge. Total hemoglobin mass (nHb), red blood cell volume (V RBC ), plasma volume (PV) and blood volume (BV) were then obtained by calculation (Christensen et al 1993).…”