C. Kees Mahutte

On-Line Arterial Blood Gas Analysis With Optodes: Current Status

OBJECTIVESnTo summarize the rationale for and the principles of blood gas and pH measurement with photochemical sensors (optodes) placed in the arterial line--either intravascularly (in vivo) or extravascularly (ex vivo). To review the specific problems that occur with in vivo measurement; the clinical data that have been obtained with continuous intravascular and on-demand extravascular systems; and, the role of this technology in the intensive care unit.nnnMETHODS AND RESULTSnThe principles of absorbance and fluorescent optical sensors are described. The accuracy of intravascular PO2 optodes can be affected by thrombosis, the wall effect (if the sensor touches the arterial wall it may read tissue values) and reduced blood flow past the sensor. Current optical pH, PCO2 and PO2 probe/cannula designs, including hybrid probes with electrochemical PO2 sensors, have not yet fully overcome these problems of the intravascular milieu. On-demand blood gas monitors that locate the optodes extravascularly, within the radial artery line, avoid these intravascular measurement problems. On-demand systems can have accuracy comparable to conventional laboratory blood gas analyzers. With either intravascular or extravascular measurement large patient studies are lacking and the relevant cost benefit ratios are not known.nnnCONCLUSIONnBefore intravascular monitors can be used routinely for clinical care, reliability, consistency and accuracy will have to be demonstrated in large and widely divergent patient groups. Extravascular on-demand blood gas analysis is accurate, allows trend monitoring of blood gases and decreases the risk of infection, the therapeutic decision time and patient blood loss. As large patient studies are lacking the clinical role of on-line blood gas analysis cannot be clearly delineated.

Experimental and predicted dual oximetry variability

AbstractObjective. We wished to determine whether the individual bias (mean difference) and precision (standard deviation of the difference) values of 2 variables, arterial oxygen saturation (SaO2) and mixed venous oxygen saturation (S⊻O2), could be used to predict the bias and precision values of the combined dual oximetry variable (SaO2- S⊻O2).Methods. We simultaneously measured SaO2 by pulse oximetry and arterial blood gas co-oximetry and S⊻O2 by fiberoptic reflectance oximetry pulmonary artery catheter and venous blood gas co-oximetry in 238 data sets from 55 patients. Three different methods were used to predict the standard deviation of the difference ofn

Relationship of thermodilution cardiac output to metabolic measurements and mixed venous oxygen saturation.

(SaO_2 - Sbar vO_2 )[s_{Delta (SaO_2 - Sbar vO_2 )} ]

Etiology of Carbon Dioxide Retention at Rest and during Exercise in Chronic Airflow Obstruction

n: simple sum, root mean square (RMS) error, and RMS error with correction term. We derived the equation for the RMS error with correction term because initial results showed that the simple sum and RMS error methods did not predictn

Ventilator Modes: Old and New

s_{Delta (SaO_2 - Sbar vO_2 )}

Drug-induced Pulmonary Edema in a Patient Infected With Human Immunodeficiency Virus

n well. The correction term accounts for the non-independence of simultaneous SaO2 and S⊻O2 measurements.Results. The observed overall bias of the SaO2, SvO2, and (SaO2 - S⊻O2) measurement methods were 0.17, –1.76, and 1.94, respectively. The observed overalln