Comparison between continuous non-invasive estimated cardiac output by pulse wave transit time and thermodilution method.

Aims and Objectives: Cardiac output (CO) measurement is essential for many therapeutic decisions in anesthesia and critical care. Most available non‑invasive CO measuring methods have an invasive component. We investigate “pulse wave transit time” (estimated continuous cardiac output [esCCO]) a method of CO measurement that has no invasive component to its use. Materials and Methods: After institutional ethical committee approval, 14 adult (21–85 years) patients undergoing surgery and requiring pulmonary artery catheter (PAC) for measuring CO, were included. Postoperatively CO readings were taken simultaneously with thermodilution (TD) via PAC and esCCO, whenever a change in CO was expected due to therapeutic interventions. Both monitoring methods were continued until patients’ discharge from the Intensive Care Unit and observer recording values using TD method was blinded to values measured by esCCO system. Results: Three hundred and one readings were obtained simultaneously from both methods. Correlation and concordance between the two methods was derived using Bland‑Altman analysis. Measured values showed significant correlation between esCCO and TD (r = 0.6, P < 0.001, 95% confidence limits of 0.51-0.68). Mean and (standard deviation) for bias and precision were 0.13 (2.27) L/min and 6.56 (2.19) L/min, respectively. The 95% confidence interval for bias was ‑ 4.32 to 4.58 L/min and for precision 2.27 to10.85 L/min. Conclusions: Although, esCCO is the only true non‑invasive continuous CO monitor available and even though its values change proportionately to TD method (gold standard) with the present degree of error its utility for clinical/therapeutic decision‑making is questionable.

Study of changes in P wave dispersion and duration as predictors of AF in patients with primary dilated cardiomyopathy

Background: P wave duration on signal averaging ECG [PD SAECG] and P wave dispersion [PWD] on standard ECG are non invasive markers of intra-atrial conduction time disturbances, the major electrophysiological cause of atrial fibrillation [AF]. P wave abnormalities have been previously studied in some cardiac conditions, however little data are available in patients with primary dilated cardiomyopathy [DCM]

Objectives: to study changes in PD and PWD as predictors of AF among patients with primary DCM and to correlate these changes with degree of severity of CHF

Patients and Methods: Surface ECG, SAECG and Transthoracic [TTE] echo were performed in 33 patients with primary DCM [Group I] and 30 age and sex matched healthy controls [Group II]. We measured heart rate [HR], minimal p wave [P min], maximal p wave [P max], P wave dispersion [difference between P min and P max = PWD] in surface ECG, P wave duration [PD] in SAECG, Left atrial maximal [LAMX], minimal [LAMN], LA volume at onset of p-wave [LAV p], LA ejection fraction [LA EF], and left ventricular ejection fraction [LV EF] by TTE

Results: There was no significant difference between groups regarding age [42.06 +/- 12.9 Vs 38.5 +/- 10.9, p=0.25] or sex distribution [24/33 [72.7%] Vs 21/30 [70%] males, p=0.81]. Patients with primary DCM showed significantly increased HR, P max and P mm, prolonged PD, and increased PWD, [p<0.0001 for all]. They showed also significantly depressed LV EF and LA EF, with a significantly increased LAMX and LAMN volume, and LAV p, [p<0.0001 for all]. Patients with DCM showed significant positive correlation between PD; and LAMX volume, LAMN volume, and LAVP, [p<0.0001 for all] and significant negative correlation between PD and both LV EF [p<0.0001] and LA EF [p=0.002]. They showed significant positive correlation between PWD; and LAMX, LAMN volume, and LAV p, [p<0.0001] and significant negative correlation between PWD and both LVEF and LAEF [p<0.0001]. Patients with severe DCM [LV EF<25%] showed significantly prolonged P max [p=0.004], P min [p=0.002], PD [p<0.0001] and increased PWD [p=0.004] compared to those with less severe form of the disease [LVER >/= 25%]

Conclusion: The prolonged P-wave duration and increased P-wave dispersion were significantly associated with the increased left atrial volumes, depressed left atrial and left ventricular systolic functions in patients with primary DCM