Relationship Between Serum Total Carbon Dioxide Concentration and Bicarbonate Concentration in Patients Undergoing Peritoneal Dialysis.

Background Few studies have assessed the relationship between serum total carbon dioxide (CO2) and bicarbonate ion (HCO3 -) concentration in patients undergoing peritoneal dialysis. We determined the agreement between serum total CO2 and HCO3 - concentration and the diagnostic accuracy of serum total CO2 for the prediction of low (HCO3 - <24 mEq/L) and high (HCO3 - ≥24 mEq/L) bicarbonate concentrations in patients on peritoneal dialysis. Methods We collected 245 samples of venous blood from 51 patients on peritoneal dialysis. Independent factors that correlated with the HCO3 - concentration were analyzed using multiple linear regression analysis. The diagnostic accuracy of serum total CO2 was evaluated by receiver operating characteristic (ROC) curve analysis and a 2×2 table. Agreement between serum total CO2 and HCO3 - concentration was assessed by Bland-Altman analysis. Results Serum total CO2 was independently correlated with HCO3 - concentration (ß = 0.354, p < 0.001). The area under the curve of serum total CO2 for the identification of low and high bicarbonate concentrations was 0.909. The diagnostic accuracy of serum total CO2 for the prediction of low and high bicarbonate concentrations was: sensitivity, 91.5%; specificity, 74.7%; positive predictive value, 53.5%; negative predictive value, 96.5%; and accuracy, 78.8%. Bland-Altman analysis showed a moderate agreement between serum total CO2 and HCO3 - concentration. Conclusion Serum total CO2 correlated closely with the HCO3 - concentration in patients undergoing peritoneal dialysis. Serum total CO2 might be useful for predicting low and high bicarbonate in peritoneal dialysis patients.

Relationship between serum total carbon dioxide concentration and bicarbonate concentration in patients undergoing hemodialysis.

BACKGROUND: Few studies have investigated the relationship between serum total carbon dioxide (CO2) concentration and bicarbonate ion (HCO3-) concentration in patients undergoing hemodialysis. We determined the agreement and discrepancy between serum total CO2 and HCO3- concentrations and the diagnostic accuracy of serum total CO2 for the prediction of low (HCO3- < 24 mEq/L) and high (HCO3- ≥ 24 mEq/L) bicarbonate concentrations in hemodialysis patients. METHODS: One hundred forty-nine arteriovenous blood samples from 84 hemodialysis patients were studied. Multiple linear regression analysis was used to determine factors correlated with HCO3- concentration. Diagnostic accuracy of serum total CO2 was evaluated using receiver operating characteristic curve analysis and a 2 × 2 table. Agreement between serum total CO2 and HCO3- concentrations was assessed using Bland-Altman analysis. RESULTS: Serum total CO2 concentration was closely correlated with HCO3- concentration (ß = 0.858, P < 0.001). Area under the curve of serum total CO2 for the identification of low and high bicarbonate concentrations was 0.989. Use of serum total CO2 to predict low and high bicarbonate concentrations had a sensitivity of 100%, specificity of 50.0%, positive predictive value of 96.5%, negative predictive value of 100%, and accuracy of 96.6%. Bland-Altman analysis showed moderate agreement between serum total CO2 and HCO3- concentrations. Discrepancies between HCO3- and serum total CO2 concentrations (serum total CO2 - HCO3- ≤ -1) were observed in 89 samples. CONCLUSION: Serum total CO2 concentration is closely correlated with HCO3- concentration in hemodialysis patients. However, there is a non-negligible discrepancy between serum total CO2 and HCO3- concentrations.

Approximation of bicarbonate concentration using serum total carbon dioxide concentration in patients with non-dialysis chronic kidney disease.

BACKGROUND: We investigated the relationship between serum total carbon dioxide (CO2) and bicarbonate ion (HCO3-) concentrations in pre-dialysis chronic kidney disease (CKD) patients and devised a formula for predicting low bicarbonate (HCO3- < 24 mmol/L) and high bicarbonate (HCO3- ≥ 24 mmol/L) using clinical parameters. METHODS: In total, 305 samples of venous blood collected from 207 pre-dialysis patients assessed by CKD stage (G1 + G2, 46; G3, 50; G4, 51; G5, 60) were investigated. The relationship between serum total CO2 and HCO3- concentrations was analyzed using Pearson's correlation coefficient. An approximation formula was developed using clinical parameters correlated independently with HCO3- concentration. Diagnostic accuracy of serum total CO2 and the approximation formula was evaluated by receiver operating characteristic curve analysis and a 2 × 2 table. RESULTS: Serum total CO2 correlated strongly with HCO3- concentration (r = 0.91; P < 0.001). The following approximation formula was obtained by a multiple linear regression analysis: HCO3- (mmol/L) = total CO2 - 0.5 × albumin - 0.1 × chloride - 0.01 × (estimated glomerular filtration rate + blood glucose) + 15. The areas under the curves of serum total CO2 and the approximation formula for detection of low bicarbonate and high bicarbonate were 0.981, 0.996, 0.993, and 1.000, respectively. This formula had superior diagnostic accuracy compared with that of serum total CO2 (86.6% vs. 81.3%). CONCLUSION: Serum total CO2 correlated strongly with HCO3- concentration in pre-dialysis CKD patients. An approximation formula including serum total CO2 showed superior diagnostic accuracy for low and high bicarbonate compared with serum total CO2.

Novel automated pulse immunoassay for human alpha-fetoprotein.

BACKGROUND: To improve current alpha-fetoprotein (AFP) assays, which are expensive and time-consuming, a specific AFP reagent has been developed for practical use in our newly developed high-speed, highly sensitive pulse immunoassay (PIA) system, in which a latex immunoagglutination reaction is carried out under a high-frequency pulse voltage, leading to an enhanced immunological reaction. METHODS: We evaluated the assay performance (reproducibility, sensitivity, dilution linearity, interference) of the newly developed automated AFP PIA compared with the current AFP assay. RESULTS: Using pooled serum samples, the within-run reproducibility resulted in a correlation variation of 3.6-4.7%. The AFP assay detection limit was determined to be 2.5 microg/L. Linear sequential dilution was found up to nearly 700 microg/L. Even up to an AFP concentration of 1.0 g/L, the prozone phenomenon was not observed. Free and conjugated bilirubin, haemolytic haemoglobin, chyle and rheumatoid factor did not show any test interference. Using AFP-positive serum samples from 114 patients, the correlation between our PIA and a chemiluminescence immunoassay resulted in an excellent correlation coefficient of 0.994. CONCLUSIONS: The performance of AFP reagents in the PIA device shows that the system has excellent speed and equal sensitivity and specificity compared with the most highly sensitive conventional method. Our PIA system thus appears ready for use in the clinical diagnosis setting.

[Transcutaneous carbon dioxide and oxygen measurement in patients undergoing microlaryngosurgery with high frequency jet ventilation].

BACKGROUND: High frequency jet ventilation (HFJV) via thin tracheal tube is a convenient method of ventilation in microlaryngosurgery, but the problem of the assessment of oxygen and carbon dioxide status during HFJV is yet to be studied. METHODS: Fifteen patients undergoing microlaryngosurgery under total intravenous anesthesia with HFJV were studied. The combined transcutaneous carbon dioxide (PtcCO2) and oxygen (PtcO2) levels were compared with arterial blood gas values (PaCO2, PaO2). RESULTS: The PtcCO2 values demonstrated a high degree of correlation with PaCO2 before intubation (r = 0.97), during HFJV (r = 0.96), and after anesthesia (r = 0.93). The PaO2 values demonstrated a generally good correlation with PaO2 before intubation (r = 0.78) and during HFJV (r = 0.83), but not after anesthesia (r = 0.54). CONCLUSION: Capnography values are invalid during HFJV, and an arterial catheter is not always indicated and feasible in microlaryngoscopy. The transcutaneous devices provide an effective method for non-invasive monitoring of PaCO2 in situations where continuous and precise control of CO2 levels is desired such as in perioperative period of microlaryngosurgery with HFJV.