Use of different approaches of acid-base derangement to predict mortality in critically ill patients.

BACKGROUND: There have been controversial data regarding the application of acid-base analysis based on Stewart methodology to predict clinical outcome in different populations. OBJECTIVE: To compare predictive ability of the physicochemical approach and the traditional bicarbonate approach of acid-base analysis in critically ill patients in relation to 28-days mortality and to evaluate the use of the physico chemical approach determined by the strong ion gap (SIG) in 1) medical compared to surgical critically ill patients; and 2) sepsis compared to non-sepsis patients. MATERIAL AND METHOD: This retrospective cohort study included 410 critically ill patients in the adult medical and surgical intensive care units (ICU) at a tertiary care hospital over a 2-year period. For each patient, values derived from the bicarbonate approaches including anion gap (AG), corrected anion gap (cAG) and lactate and those obtained from the physicochemical approach like SIG were simultaneously computed at ICU admission. The comparison of predictive ability between different approaches was assessed by forward stepwise logistic regression and the area under the receiver operating characteristic (aROC) curves. RESULTS: Of the 410 patents enrolled, 205 (50%) were admitted in the medical ICU and 226 patients (55%) were male. Overall 28-day mortality was 44.6% (183/410). The comparison between medical and surgical patients showed no difference in age (59 vs. 64 yr), APACHE II score (21 vs. 20), presence of sepsis (71% vs. 70%) and 28-day mortality (45% vs. 44%). Acid-base disturbance in non-survivors (n = 183) and survivors (n = 227) determined by pH (7.39 +/- 0.04 vs. 7.41 +/- 0.01), serum bicarbonate (16.0 +/- 6.1 vs. 17.9 +/- 7.4) and PaCO2 (32.4 +/- 13.4 vs. 29.4 +/- 8.2) were comparable. However non-survivors had higher levels of SIG (9.7 +/- 6.2 vs. 6.4 +/- 5.2) and cAG (27.5 +/- 8.8 vs. 20.3 +/- 8.6) than survivors did. According to a ROC curves, the predictive ability to discriminate between survivors and non-survivors of lactate, cAG AG and SIG are 0.77, 0.72, 0.68 and 0.67, respectively. Correlations between the SIG and values derived from bicarbonate approach are fair. There was no difference in SIG values between surgical and medical patients with the same severity scores. Sepsis patients (n = 291) had significantly higher SIG than non-sepsis patients (n = 129) did (8.81 +/- 6.38 vs. 5.74 +/- 4.14; p = 0.01). CONCLUSION: Compared to the traditional approach, an alternative Stewart approach does not provide any greater advantage to predict mortality in the studied population. Because of complex calculation, the usefulness of such approach on the routine clinical practice may be limited.

Dynamics of central venous oxygen saturation and serum lactate during septic shock resuscitation.

BACKGROUND: Septic shock is a serious condition leading to high mortality and morbidity. Many varieties of attempts aiming toward improving outcomes have been implemented. However the appropriate therapeutic endpoint of shock resuscitation is still under investigation. The authors report here the dynamics of commonly used parameters, namely central venous oxygen saturation (ScvO2) and lactate concentration during resuscitation. MATERIAL AND METHOD: Adult patients admitted with severe sepsis and septic shock from October 1, 2009 to January 31, 2009 were enrolled. During hemodynamic resuscitation, the central venous blood was drawn for ScvO2 and lactate measurement right after the CVC was placed (T1) and at the point where the blood pressure goal was achieved (T2). The third and the fourth measurements were obtained at 1 and 2 hours thereafter (T3 and T4). These samples were ice chilled and were sent to central laboratory for blood gas analysis and lactate determination. RESULTS: Twenty patients underwent the study. There was no significant change in ScvO2 from T1 to T4. All but five ScvO2 at T1 were above 70%. Lactate level gradually declined during the course of treatment and the clearance from T1 to T3 was calculated as 15.4%. No correlation between ScvO2 and lactate level was noted at any sampling time. When partitioning venous oxygen saturation in to 4 groups, that is ScvO2 < 65, 65 - < 75, 75-<85 and > 85, respectively, those with ScvO2 > 85% had the highest lactate concentration. CONCLUSION: Central venous oxygen saturation and its changes during treatment were heterogeneous which made this parameter less reliable than others to monitor management. The lactate clearance, although slow, is uniform and may be used alone or in combination with other parameters to monitor resuscitation.

Correlation of arterial, central venous and capillary lactate levels in septic shock patients.

BACKGROUND: Blood lactate level increases in response to tissue hypoxia and this level is currently used to monitor shock management. To obtain the arterial lactate value in clinical practice is a time consuming process. Our previous study demonstrated good correlation between the capillary lactate determined by a portable lactate analyzer and the standard arterial lactate in critically ill patients. This study was aimed to examine the uses of this capillary lactate in septic shock. MATERIAL AND METHOD: A prospective comparison of arterial, venous and capillary lactate level from septic shock patients admitted in the general wards and the Medical ICU, Department of Medicine, Siriraj hospital was performed during October 2009 to February 2010. RESULTS: Thirty patients were included in the study. The mean age was 66 (24-86) years and 16 (53%) were female. The correlation between arterial and central venous was 0.992 and the correlation between arterial and capillary lactate level was 0.945 (p = 0.01 in both comparisons). In addition, there was certain agreement between the arterial and the capillary lactate especially when arterial lactate was below 10 mmol/L. CONCLUSION: The capillary lactate level determined by the portable lactate analyzer (Accutrend Plus) correlated well with arterial lactate level. This method, when used cautiously, may be used to monitor septic shock treatment as an alternative to the standard arterial lactate determination.

Right ventricular dysfunction in septic shock.

BACKGROUND: Right ventricular dysfunction (RVD) is common in critically ill patients and the presence of this condition affects patients' outcomes. Improving the knowledge background and establishing the incidence of RVD in septic shock patients would render the management more efficacious. This study was performed to evaluate the incidence and outcomes of RVD in septic shock patients. MATERIAL AND METHOD: A single center retrospective observational study was performed in the Medical ICU, Siriraj Hospital, Mahidol University between January 2007 and October 2009. Patients with septic shock in whom pulmonary artery catheter (PAC) was inserted were included in the study. RESULTS: The PAC was placed in 118 patients during the study period. The patients' mean age was 58.0 +/- 18.5 years and 71 of them (59.3%) were male. The mean body mass index was 25.0 +/- 6.6 Kg/m2 and the mean APACHE II score was 26.1 +/- 7.7. The admission diagnoses were severe sepsis or septic shock (70%), severe pneumonia (38%), acute respiratory distress syndrome (21%). Twenty one patients (17.8%) meet the diagnosis criteria of RVD. The hospital mortality in RVD patients tended to be higher than the non-RVD patients (81.0% vs. 60.8%, p 0.06). Although similar proportions of both group received ventilatory support, the RVD patients had lower tidal volume and had higher peak airway pressure. Also the RVD group had lower PaO2/FiO2 ratio. In addition, the RVD group had lower cardiac output and more frequently underwent renal replacement therapy. CONCLUSION: In patients with septic shock, the incidence of RVD is substantial. The significant factors associated with RVD include low tidal volume and high peak airway pressure. Measures to prevent the alteration in lung compliance in septic shock patients may prevent RVD and improve patients' outcomes.

Impact of septic shock hemodynamic resuscitation guidelines on rapid early volume replacement and reduced mortality.

BACKGROUND: Septic shock is one of the most serious conditions associated with high mortality. We recently developed a modified septic shock management guideline focusing on rapid restoration of hemodynamics by using clinical endpoint. Our aim was to analyze patients' outcomes following the guideline implementation. MATERIAL AND METHOD: A retrospective review of hemodynamic data sheet and clinical outcomes of patients admitted to medical ICU and medical Wards and during June 2004 and February 2006. RESULTS: One hundred and four patients' records were retrieved. The patients' mean age was 62.5 +/- 18.6 year. Their mean APACHE II score were 24.9 +/- 6.7 and the overall mortality was 59%. Sixty eight patients (65.4%) underwent guideline directed therapy (guideline group). The guideline group received higher volume resuscitation from the first hour of resuscitation (1,016.3 + 675.0 ml vs. 521.4 + 359.2 ml, p < 0.001) to the forty eighth hour (10,096.9 +/- 3,256.1 ml vs. 8,067.3 +/- 2,591.9 ml, p = 0.006). More of them achieved the therapeutic goal within 6 hours (86.8% vs. 44.4%, p < 0.001) and their hospital mortality was lower (41.2% vs. 69.4%, p = 0.008). When analyzing differences between those who survived and those who died, more of the surviving patients underwent guideline directed treatment (79.5% vs. 55%, p = 0.012). They received higher volume replacement from the first hour to the end of the twelfth hour (first hour 1,098.0 +/- 723.0 vs. 660.9 +/- 478.9 ml, p < 0.001; the end of the twelfth hour 3,746.6 +/- 1,799 vs. 3,014.1 +/- 1,579.9 ml, p = 0.038) and more of them achieved the therapeutic goal within 6 hours (95.5% vs. 55%, p < 0.001). Multivariate analysis of factors associated with mortality disclosed APACHE II score, volume resuscitation more than 800 ml in the first hour and achievement of the therapeutic goal within 6 hours. CONCLUSION: Implementation of our modified septic shock guideline is associated with rapid initial volume replacement, prompt achievement of therapeutic goal and improved outcomes. Volume resuscitation greater than 800 ml in the first hour is associated with better survival.