Central Venous Blood Gas Analysis Research Articles

Effect of open-lung ventilation strategy on oxygenation-impairment during laparoscopic colorectal cancer resection

Objective: After general anesthesia and mechanical ventilation for laparoscopic colorectal cancer resection, about 90% of patients would have different degrees of atelectasis. Authors speculated that an open-lung strategy (OLS) comprising moderate positive end-expiratory pressure (PEEP) and intermittent recruitment maneuvers (RM) can reduce atelectrauma and thus reduce the incidence of oxygenation-impairment during low-tidal-volume ventilation for laparoscopic colorectal cancer resection. The purpose of this study was to verify this hypothesis and provide a better intraoperative ventilation scheme for laparoscopic colorectal cancer resection. Methods: This was a prospectively randomized controlled clinical trial which was approved by the Ethics Committee of the Sixth Affiliated Hospital, Sun Yat-sen University (2017ZSLYEC-002), and registered at the ClinicalTrials.gov (NCT03160144). From January to July 2017, patients who underwent laparoscopic colorectal cancer resection, with age > 40 years, estimated pneumoperitoneum time ≥ 1.5 h, pulse oxygen saturation ≥ 92%, and risk grade for postoperative pulmonary complications ≥ 2 were prospectively enrolled. The patients with American Society of Anesthesiologists physical status ≥ IV, body mass index ≥ 30 kg/m(2), pneumonia, acute respiratory failure or sepsis within 1 month, severe chronic obstructive pulmonary disease, pulmonary bullae and progressive neuromuscular diseases, and those participating in other interventional clinical trials were excluded. The enrolled patients were randomly assigned (1:1) to the OLS group (with a PEEP of 6-8 cm H(2)O and intermittent RM), and the NOLS group (without using PEEP and RM). Partial pressure of arterial oxygen (PaO(2)) /fraction of inspired oxygen (FiO(2)) and shunt fraction (Q(S)/Q(T)) were calculated via arterial and central venous blood gas analysis performed at 0.5 h (T(1)), 1.5 h (T(2)) after pneumoperitoneum induction and at 20 min after admission to the recovery room. Driving pressure immediately before pneumoperitoneum induction (T(0)) and at T(2) were calculated via monitoring data. The primary outcome was oxygenation-impairment (PaO(2)/FiO(2) ≤ 300 mmHg) during mechanical ventilation. Results: In each group, 48 patients under general anesthesia and low-tidal-volume ventilation were included in the final analysis. During ventilation, the oxygenation-impairment occurred in 7 patients (14.6%) of OLS group and in 17 patients (35.4%) of NOLS group, whose difference was statistically significant between two groups (χ(2)=5.556, RR=0.31, 95%CI: 0.12 to 0.84, P=0.033). During ventilation, the patients in the OLS group had higher PaO(2)/FiO(2) [T(1): (427±103) mmHg vs. (366±109) mmHg, t=-2.826, P=0.006; T(2): (453±103) mmHg vs. (388±122) mmHg, t=-2.739, P=0.007], lower Q(S)/Q(T) [ T(1): (9.2±6.5) % vs. (12.6±7.7) %, t=2.322, P=0.022; T(2): (7.0±5.8)% vs.(10.9±9.2)%, t=2.408, P=0.019], and lower driving pressure [T(0): (6±3) cm H(2)O vs. (10±2) cm H(2)O, t=7.421, P<0.001; T(2): (13±3) cm H(2)O vs. (17±4) cm H(2)O, t=5.417, P<0.001] than those in the NOLS group, with stratistical differences in all comparisons. In recovery room, though PaO(2)/FiO(2) [(70.3±9.4) mmHg vs. (66.8±9.4) mmHg, P=0.082] was still higher and Q(S)/Q(T) [(18.6±8.3)% vs. (21.8±8.4)%, P=0.070] was still lower in the OLS group as compared to the NOLS group, the differences were not statistically significant (both P>0.05). Conclusion: The application of such an OLS during low-tidal-volume ventilation can greatly reduce the incidence of oxygenation-impairment in laparoscopic colorectal cancer resection, and such effect may last to the period of emergence from anesthesia.

Cold non-ischemic heart preservation with continuous perfusion prevents early graft failure in orthotopic pig-to-baboon xenotransplantation.

Successful preclinical transplantations of porcine hearts into baboon recipients are required before commencing clinical trials. Despite years of research, over half of the orthotopic cardiac xenografts were lost during the first 48hours after transplantation, primarily caused by perioperative cardiac xenograft dysfunction (PCXD). To decrease the rate of PCXD, we adopted a preservation technique of cold non-ischemic perfusion for our ongoing pig-to-baboon cardiac xenotransplantation project. Fourteen orthotopic cardiac xenotransplantation experiments were carried out with genetically modified juvenile pigs (GGTA1- KO/hCD46/hTBM) as donors and captive-bred baboons as recipients. Organ preservation was compared according to the two techniques applied: cold static ischemic cardioplegia (IC; n=5) and cold non-ischemic continuous perfusion (CP; n=9) with an oxygenated albumin-containing hyperoncotic cardioplegic solution containing nutrients, erythrocytes and hormones. Prior to surgery, we measured serum levels of preformed anti-non-Gal-antibodies. During surgery, hemodynamic parameters were monitored with transpulmonary thermodilution. Central venous blood gas analyses were taken at regular intervals to estimate oxygen extraction, as well as lactate production. After surgery, we measured troponine T and serum parameters of the recipient's kidney, liver and coagulation functions. In porcine grafts preserved with IC, we found significantly depressed systolic cardiac function after transplantation which did not recover despite increasing inotropic support. Postoperative oxygen extraction and lactate production were significantly increased. Troponin T, creatinine, aspartate aminotransferase levels were pathologically high, whereas prothrombin ratios were abnormally low. In three of five IC experiments, PCXD developed within 24 hours. By contrast, all nine hearts preserved with CP retained fully preserved systolic function, none showed any signs of PCXD. Oxygen extraction was within normal ranges; serum lactate as well as parameters of organ functions were only mildly elevated. Preformed anti-non-Gal-antibodies were similar in recipients receiving grafts from either IC or CP preservation. While standard ischemic cardioplegia solutions have been used with great success in human allotransplantation over many years, our data indicate that they are insufficient for preservation of porcine hearts transplanted into baboons: Ischemic storage caused severe impairment of cardiac function and decreased tissue oxygen supply, leading to multi-organ failure in more than half of the xenotransplantation experiments. In contrast, cold non-ischemic heart preservation with continuous perfusion reliably prevented early graft failure. Consistent survival in the perioperative phase is a prerequisite for preclinical long-term results after cardiac xenotransplantation.

Comparison of Simultaneously Obtained Central Venous Blood Gas and Arterial Blood Gas Analysis for pH, pCO2, BE and K+ in Patients Attending Emergency Medicine of Tertiary Care Centre

Comparison of Simultaneously Obtained Central Venous Blood Gas and Arterial Blood Gas Analysis for pH, pCO2, BE and K+ in Patients Attending Emergency Medicine of Tertiary Care Centre

Right ventricular adaptation in the critical phase after acute intermediate-risk pulmonary embolism.

The haemodynamic response following acute, intermediate-risk pulmonary embolism is not well described. We aimed to describe the cardiovascular changes in the initial, critical phase 0-12 hours after acute pulmonary embolism in an in-vivo porcine model. Pigs were randomly allocated to pulmonary embolism (n = 6) or sham (n = 6). Pulmonary embolism was administered as autologous blood clots (20 × 1 cm) until doubling of mean pulmonary arterial pressure or mean pulmonary arterial pressure was greater than 34 mmHg. Sham animals received saline. Cardiopulmonary changes were evaluated for 12 hours after intervention by biventricular pressure-volume loop recordings, invasive pressure measurements, arterial and central venous blood gas analyses. Mean pulmonary arterial pressure increased (P < 0.0001) and stayed elevated for 12 hours in the pulmonary embolism group compared to sham. Pulmonary vascular resistance and right ventricular arterial elastance (right ventricular afterload) were increased in the first 11 and 6 hours, respectively, after pulmonary embolism (P < 0.01 for both) compared to sham. Right ventricular ejection fraction was reduced (P < 0.01) for 8 hours, whereas a near-significant reduction in right ventricular stroke volume was observed (P = 0.06) for 4 hours in the pulmonary embolism group compared to sham. Right ventricular ventriculo-arterial coupling was reduced (P < 0.05) for 6 hours following acute pulmonary embolism despite increased right ventricular mechanical work in the pulmonary embolism group (P < 0.01) suggesting right ventricular failure. In a porcine model of intermediate-risk pulmonary embolism, the increased right ventricular afterload caused initial right ventricular ventriculo-arterial uncoupling and dysfunction. After approximately 6 hours, the right ventricular afterload returned to pre-pulmonary embolism values and right ventricular function improved despite a sustained high pulmonary arterial pressure. These results suggest an initial critical and vulnerable phase of acute pulmonary embolism before haemodynamic adaptation.

Anesthesiologist’s learning from experience of participating in the treatment of critically ill patients with COVID-19 in isolation wards

After the outbreak of 2019 novel coronavirus diseases (COVID-19), the number of severe cases in Wuhan increased dramatically, which was far beyond the load of ICU. As a result, the isolation ward became the place for the treatment of severe cases. Because the important role of anesthesiologists, more than 20 anesthesiologists from Union Hospital of Tongji Medical College, Huazhong University of Science and Technology have been sent to eight isolation wards of severe patients. They have participated in the treatment of more than 800 severe COVID-19 patients, including more than 300 critical cases and more than 120 cases were getting better recovery. Their work included endotracheal intubation, central venous catheterization, artery cannulation and blood gas analysis, and bedside cardiopulmonary ultrasound examination, and more importantly they have played an important role in respiratory management after endotracheal intubation, the treatment of cardiovascular events and precise fluid therapy. During these works, anesthesiologists improved their own professional skills through the cooperation with other specialists, including the standard writing skills of medical records and prescription, appropriate protection against infectious diseases, standard medication and oxygen therapy for respiratory diseases, and the capability of continuously management of critical cases. Key words: Anesthesiologists; Hospitals, isolation; Critical care; COVID-19

Prospective, observational study of carbon dioxide gaps and free energy change and their association with fluid therapy following cardiac surgery.

Background Venoarterial carbon dioxide pressure (pv-a CO2 ) and content (Cv-a CO2 ) differences, including the ratio to arteriovenous oxygen content difference (Ca-v O2 ), and free energy changes (-∆∆Ga-v ) may reflect tissue hypoperfusion. The associations with changes in cardiac output (CO) or oxygen consumption (VO2 ) following fluid bolus administration were investigated. Methods Single-centre, observational study of 89 adult post-operative cardiac surgical patients admitted to ICU. The pv-a CO2 , Cv-a CO2 and their ratios to Ca-v O2 as well as the -∆∆Ga-v were determined before and after a 250-500mL fluid bolus using arterial, central venous and mixed venous blood gas analyses. Responses associated with changes ≥ or <15% in CO or oxygen consumption (VO2 ) were compared. Results In 234 boluses, the mixed venous to arterial pv-a CO2 and its ratio to Ca-v O2 were independently associated with an increase in CO; odds ratio 1.3 (95% CI 1.1-1.5) and 1.7 (95% CI 1.5-1.9) respectively, P<.001) and VO2 ; odds ratio 2.1 (95% CI 1.3-3.1), P<.001 for Ca-v O2 . No measures of pv-a CO2 , Cv-a CO2 or related ratios to the Ca-v O2 were associated with an increase in CO ≥15% following a single volume bolus. The mixed venous and central venous Cv-a CO2 to Ca-v O2 ratios were different for the first bolus episode only; mean differences 0.81 (95% CI 0.13-1.5), P=.02 and 0.44 (95% CI 0.06-0.82), P=.02, respectively, for increased VO2 ≥15%. The -∆∆Ga-v did not change. Conclusion The venoarterial carbon dioxide gradients and related calculations to assess the adequacy of tissue perfusion before a fluid bolus were not associated with subsequent increases in CO of oxygen consumption. Editorial Comment In some shock conditions, regional tissue hypoperfusion can be obvious and arterio-venous differences for CO2 or O2 may reflect this. This is not always the case; sometimes there are A-V differences or even a high lactate level without any obvious regional tissue hypoperfusion. Fluid therapy is a cornerstone in shock resuscitation treatment, but determining optimal fluid therapy is challenging, particularly as fluid overload may be detrimental. Fluid challenges are used as an "ex juvantebus" method to dose fluid therapy, but it is not clear if a positive response reflects a state of hypoperfusion or the existence of a cardiac reserve. Still, a better understanding on how to target and guide fluid therapy is welcome, and studies digging into the problem are needed. Here, invasively monitored post-operative cardiac surgery patients are assessed as a model to investigate if carbon dioxide gaps and free energy charge may be useful in detecting possible tissue hypoperfusion.

End Tidal Carbon dioxide can track cardiac output changes during fluid challenge in Shocked Mechanically Ventilated Patients

Background: In this study, we investigated the ability of end tidal carbon dioxide pressure (PETCO2) to monitor the changes in cardiac output (CO) induced by fluid challenge and to predict fluid responsiveness. Patients and Methods: We conducted our study upon 38 shocked patients requiring fluid challenge (FC). Hemodynamic variables, central venous pressure (CVP), End-tidal CO2, arterial and venous blood gas analysis and cardiac output were recorded before and after fluid challenges. Fluid responders were identified when cardiac output increased more than 15% after fluid challenge, cardiac output (CO) was estimated by measuring left ventricular outflow tract velocity-time integral (LVOT VTI) by transthoracic doppler echocardiography. Results: Twenty-one (55.3%) patients were fluid responders. Fluid challenge induced increase in CO and PETCO2 was moderately correlated (r = 0.5; P 0.002). The area under receiver operating characteristic (ROC) curve of Δ PETCO2 was 0.89±0.05 CI (81- 98) with an increase ≥ 3.13% in PETCO2 can predict fluid responsiveness with 85.7% sensitivity and 88.3% specificity. No other clinical or hemodynamic variables can predict fluid responsiveness. The area under ROC curve of ΔCVP was 0.48±0.1 CI (32- 64) with an increase ≥ 2cmH2O in CVP can predict fluid responsiveness with 38% sensitivity and 76.5% specificity. Conclusions: Our findings indicate that induced changes in PETCO2 during fluid challenge could be used to monitor changes in cardiac output (CO) for prediction of fluid responsiveness in mechanically ventilated shocked patients, under stationary minute ventilation and steady CO2 production

Central Venous Blood Gas Analysis: An Alternative to Arterial Blood Gas Analysis for pH, PCO2, Bicarbonate, Sodium, Potassium and Chloride in the Intensive Care Unit Patients.

ABSTRACTAimsArterial blood gas (ABG) analysis is a frequently ordered test in intensive care unit (ICU) and can analyze electrolyte in addition to pH and blood gases. Venous blood gas (VBG) analysis is a safer procedure and may be an alternative for ABG. Electrolyte estimation by auto analyzer usually takes 20–30 minutes. This study was aimed to investigate the correlation of pH, PCO2, bicarbonate, sodium, potassium, and chloride (electrolytes) between ABG and central VBG in ICU patients.Materials and methodsThis was a prospective observational study conducted in medical college hospital ICU. Adult patients requiring ABG and electrolyte estimation as a part of their clinical care were consecutively included in the study. Patients having any intravenous infusion or who were pregnant were excluded. Venous samples were taken within 2 minutes of arterial sampling from in situ central line. Data were analyzed using Bland-Altman methods.ResultsA total of 110 patients' paired blood samples were analyzed. The mean difference between arterial and central venous values of pH, PCO2, bicarbonate, sodium, potassium, and chloride was 0.04 units, –5.84 mm Hg, 0.89 mmol/L, –1.8 mEq/L, –0.04 mEq/L, and –0.89 mEq/L, respectively. The correlation coefficients for pH, PCO2, HCO3−, sodium, potassium, and chloride were 0.799, 0.831, 0.892, 0.652, 0.599 and 0.730, respectively. Limits of agreement (95%) were within acceptable limits.ConclusionCentral venous pH, PCO2, and bicarbonate may be an acceptable substitute for ABG in patients admitted in the ICU. However caution should be exercised while applying electrolyte measurements.How to cite this articleBijapur MB, Kudligi NA, Asma S. Central Venous Blood Gas Analysis: An Alternative to Arterial Blood Gas Analysis for pH, PCO2, Bicarbonate, Sodium, Potassium and Chloride in the Intensive Care Unit Patients. Indian J Crit Care Med 2019;23(6):258–262.

Using peripheral perfusion index and venous-to-arterial CO(2) difference/arterial-central venous O(2) difference ratio to assess lactate clearance in septic patients after resuscitation

Objective: The relationship of venous-to-arterial CO(2) difference(Pv-aCO(2))/arterial-central venous O(2) difference (Ca-vO(2)) ratio, peripheral perfusion index(PI) and lactate clearance(LC) were investigated during resuscitation in septic patients. And, the meaning of the combination PI and Pv-aCO(2)/Ca-vO(2) ratio to interpret incoherence of lactate clear was explored. Methods: The patients with sepsis were prospectively observed, who admitted to critically care medicine department of Peking Union Medical College Hospital. The hemodynamic parameters, simultaneous arterial and central venous blood gas analysis and PI were obtained at the enrollment (T0) and 8 hours (T8) during resuscitation. The lactate clearance was defined as 8h-LC≥10% and non-lactate clearance was defined as 8h-LC ≤ 10%. Additionally, the patients were divided as three sub-groups according to the PI value at T8: the normalized PI group with PI≥1.4,the mild impaired PI with 1.4<PI<0.6 and severe impaired PI with PI≤0.6. Results: A total of 84 patients were enrolled in this study. There was no significant difference in Pv-aCO(2)/Ca-vO(2) ratio in the three groups. However, the PI≤0.6 group had a significantly higher Pv-aCO(2) than other groups. Moreover, the patients with non-lactate clearance (13/32) had a higher Pv-aCO(2)/Ca-vO(2) ratio than the patients with lactate clearance in PI≥1.4 group (1.9±0.7 vs. 1.3±1.0, P=0.01). Multivariate analysis showed both Pv-aCO(2)/Ca-vO(2) ratio [Exp(B) 2.235, 95% CI 1.232-4.055, P=0.008] and acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) [Exp (B) 1.087, 95%CI 1.022-1.156, P=0.008] were independent risk factor of non-lactate clearance. 8h-PI was significantly negative correlated with the 8 h Pv-aCO(2) gap (r=-0.311, P=0.004), but not significantly with Pv-aCO(2)/Ca-vO(2) ratio (r=-0.094, P=0.385). Conclusions: Both high Pv-aCO(2)/Ca-vO(2) ratio and low PI were related to non-lactate clearance after resuscitation in sepsis. Combined PI and Pv-aCO(2)/Ca-vO(2) ratio could interpret incoherence of latacte clearance after resuscitation.

Monitoring of Tissue Oxygenation: an Everyday Clinical Challenge

The aim of this article is to study the overview of pathophysiology and clinical application of central venous oxygen saturation monitoring in critically ill patients and during the perioperative period. There are several clinical studies and animal experiments evaluating the effects of goal-directed hemodynamic stabilization on critically ill patients. Recent systematic reviews and meta-analyses found that advanced hemodynamic endpoints-targeted management has a positive effect on outcome in high-risk surgical patients. As all interventions aim to improve tissue oxygenation, it is of utmost importance to monitor the balance between oxygen delivery and consumption. For this purpose, central venous blood gas analysis provides an easily available tool in the everyday clinical practice. The adequate interpretation of central venous oxygen saturation renders the need of careful evaluation of several physiological and pathophysiological circumstances. When appropriately evaluated, central venous oxygen saturation can be a valuable component of a multimodal individualized approach, in which components of oxygen delivery are put in the context of the patients' individual oxygen consumption. In addition to guide therapy, central venous oxygen saturation may also serve as an early warning sign of inadequate oxygen delivery, which would otherwise remain hidden from the attending physician. With the incorporation of central venous oxygen saturation in the everyday clinical routine, treatment could be better tailored for the patients' actual needs; hence, it may also improve outcome.

Accuracy of Peripheral and Central Venous Blood Gas Analysis in Evaluating Patients with Respiratory Failure

Objectives: Arterial blood samples are the gold standard test but these are more difficult to get than venous samples. In this study we assessed the possibility of utilization of venous (peripheral and central) blood gas samples in evaluation of subjects with respiratory failure instead of arterial samples. Methods: critically ill subjects with respiratory failure had paired venous (peripheral and central) and arterial samples taken. Assessment of agreement between blood gas samples (arterial and venous) as regard PH, Pco2 and HCO3 was done using Bland–Altman analyses. The spearmen correlation and linear regression tests were also performed to assess the degree of association between arterial and venous samples. Results: 100subjects were included. A good agreement was found between venous (peripheral and central) and arterial values of pHand HCO3.The agreements between peripheral venous and arterial PH and HCO3 values is higher than agreements between arterial and central venous measures. Conclusions: venous blood gas analysis (mainly peripheral samples) could replace arterial blood gas analysis in the evaluation of acid base balance in subjects with respiratory failure

Comparison of Simultaneously Obtained Central Venous Blood Gas and Arterial Blood Gas Analysis for pH, pCO2, BE and K+ in Patients Presenting to Emergency Medicine and Critical Care Unit

Comparison of Simultaneously Obtained Central Venous Blood Gas and Arterial Blood Gas Analysis for pH, pCO2, BE and K+ in Patients Presenting to Emergency Medicine and Critical Care Unit

Agreement and Correlation between Arterial and Central Venous Blood Gas Following Coronary Artery Bypass Graft Surgery.

Arterial blood sampling, used to assess patients in acute conditions, may result in complications such as thrombosis and embolism. However, it can be replaced by venous blood sampling, but there is a dearth of information on this. To assess the correlation and agreement between the arterial and central venous blood gases analyses in patients undergoing elective Coronary Artery Bypass Graft (CABG) surgery. In this cross-sectional study, 100 ICU patients undergoing elective CABG surgery were recruited. 2 mm arterial and a 2 mm venous blood samples were obtained from each patient's arterial and central venous lines, respectively. To predict Arterial Blood Gas (ABG) values based on central Venous Blood Gas (VBG) values, the linear regression analysis was used and for evaluating their agreement Bland-Altman method was used. In total of 200 samples were obtained. The mean and Standard Deviation (SD) of age was 58.9±9.1 years and 51% of the participants were female. There was a strong correlation between ABG and central VBG values regarding pH, partial Pressure of Carbon Dioxide (PCO2), Bicarbonate (HCO3) and Base Excess (BE) (r= 0.73, r=0.74, r=0.67 and r=0.71, respectively; p<0.001); however, the correlation between the arterial and venous Partial Pressure of Oxygen (PO2) and Oxygen Saturation (SO2) was moderate (r=0.29, p=0.005 and r=0.27, p=0.006, respectively). The Bland-Altman analysis showed an excellent agreement between all the variables (p<0.001). Central VBG analysis cannot replace ABG analysis in measuring exact PO2 status, necessitating arterial sampling in some matters, but with respect to the accuracy of pulse oximetry measurements in determining the exact PO2 status, for the rest of the indices a central VBG rather than an ABG can be utilised for determining patient's acid-base status. Particularly in patients who are hospitalised for a long time and have a central venous catheter in place like patients who have undergone CABG, thus reducing the risk and need for invasive arterial sampling.

Correlation of central venous pressure with venous blood gas analysis parameters; a diagnostic study

ObjectiveThis study was conducted to assess the correlation between central venous pressure (CVP) and venous blood gas (VBG) analysis parameters, to facilitate management of severe sepsis and septic shock in emergency department. Material and methodsThis diagnostic study was conducted from January 2014 until June 2015 in three major educational medical centers, Tehran, Iran. For patients selected with diagnosis of septic shock, peripheral blood sample was taken for testing the VBG parameters and the anion gap (AG) was calculated. All the mentioned parameters were measured again after infusion of 500 cc of normal saline 0.9% in about 1 h. ResultsTotally, 93 patients with septic shock were enrolled, 63 male and 30 female. The mean age was 72.53 ± 13.03 and the mean Shock Index (SI) before fluid therapy was 0.79 ± 0.30. AG and pH showed significant negative correlations with CVP, While HCO3 showed a significant positive correlation with CVP. These relations can be affected by the treatment modalities used in shock management such as fluid therapy, mechanical ventilation and vasopressor treatment. ConclusionIt is likely that there is a significant statistical correlation between VBG parameters and AG with CVP, but further research is needed before implementation of the results of this study.

Vasoactive Drugs and Hemodynamic Monitoring in Pediatric Cardiac Intensive Care: An Italian Survey.

Little is known about practitioner preference, the availability of technology, and variability in practice with respect to hemodynamic monitoring and vasoactive drug use after congenital heart surgery. The aim of this study was to characterize current hospital practices related to the management of low cardiac output syndrome (LCOS) across Italy. We issued a 22-item questionnaire to 14 Italian hospitals performing pediatric cardiac surgery. Electrocardiogram, invasive blood pressure, central venous pressure, pulse oximetry, diuresis, body temperature, arterial lactate, and blood gas analysis were identified as routine in hemodynamic monitoring. With regard to advanced hemodynamic monitoring, pulmonary arterial catheter and transpulmonary thermodilution were available in 43% of the centers, uncalibrated pulse contour methods in 29% of the centers, and transesophageal/transthoracic echocardiograms in all of the centers. Dopamine added to milrinone was the most frequent drug regimen for LCOS prevention after cardiopulmonary bypass. Overall, 86% of centers used milrinone alone as the initial treatment for LCOS with elevated systemic vascular resistances and levosimendan, the second preferred choice. In cases of LCOS with low vascular resistance, epinephrine was the first choice (10 centers), dopamine was the second choice (4 centers), followed by vasopressin and norepinephrine (3 centers). For treatment of LCOS with elevated pulmonary resistances, milrinone was the first choice (eight centers), followed by inhaled nitric oxide (five centers). The survey shows that advanced hemodynamic monitoring is rarely performed. The most commonly used vasoactive drugs are milrinone, levosimendan, dopamine, epinephrine, vasopressin, and norepinephrine. Guidelines on the topic are warranted.

Effects of a 1:1 inspiratory to expiratory ratio on respiratory mechanics and oxygenation during one-lung ventilation in patients with low diffusion capacity of lung for carbon monoxide: a crossover study

Study ObjectiveTo investigate the effects of a 1:1 inspiratory-to-expiratory (I:E) ventilation ratio on oxygenation and respiratory mechanics during one-lung ventilation (OLV) in patients with low diffusion capacity of lung for carbon monoxide (DLCO). DesignProspective, randomized, crossover study. SettingOperating room, university hospital. PatientsTwenty-six patients with a preoperative DLCO less than 80% who were scheduled for lung lobectomy requiring OLV under general anesthesia. InterventionsIn the first group (n = 13), OLV was begun with a 1:1 I:E ratio, which was switched to a 1:2 I:E ratio after 30minutes. In the second group (n = 13), the modes of ventilation were performed in the opposite order. Pressure-controlled ventilation with 5 cm H2O of positive end-expiratory pressure and a tidal volume of 5 to 8mL/kg was applied during OLV. MeasurementsArterial and central venous blood gas analyses were recorded and used to calculate intrapulmonary shunt fraction and physiologic dead space. These measurements were taken at 4 time points: 10minutes after two-lung ventilation in the lateral decubitus position, 30minutes after initiation of OLV, 30minutes after switching the I:E ratio, and 10minutes after two-lung ventilation was resumed. Main ResultsThere was no difference in arterial oxygen tension during OLV between the 2 groups (P = .429). Arterial carbon dioxide tension and peak airway pressure were lower in the 1:1 group than in the 1:2 group (P = .003; P = .008). Physiologic dead space was also decreased in the 1:1 I:E ratio group (P = .003). Mean airway pressure and dynamic compliance were higher in the 1:1 group (P = .003; P = .007). ConclusionsPressure-controlled ventilation with a 1:1 I:E ventilation ratio did not improve oxygenation in patients with low DLCO during OLV compared with a 1:2 I:E ventilation ratio. However, it did provide benefits in terms of respiratory mechanics and increased the efficiency of alveolar ventilation during OLV.

Clinical practice in perioperative monitoring in adult cardiac surgery: is there a standard of care? Results from an national survey.

This study was to investigate and define what is considered as a current clinical practice in hemodynamic monitoring and vasoactive medication use after cardiac surgery in Italy. A 33-item questionnaire was sent to all intensive care units (ICUs) admitting patients after cardiac surgery. 71 out of 92 identified centers (77.2%) returned a completed questionnaire. Electrocardiogram, invasive blood pressure, central venous pressure, pulse oximetry, diuresis, body temperature and blood gas analysis were identified as routinely used hemodynamic monitoring, whereas advanced monitoring was performed with pulmonary artery catheter or echocardiography. Crystalloids were the fluids of choice for volume replacement (86.8% of Centers). To guide volume management, central venous pressure (26.7%) and invasive blood pressure (19.7%) were the most frequently used parameters. Dobutamine was the first choice for treatment of left heart dysfunction (40%) and epinephrine was the first choice for right heart dysfunction (26.8%). Half of the Centers had an internal protocol for vasoactive drugs administration. Intra-aortic balloon pump and extra-corporeal membrane oxygenation were widely available among Cardiothoracic ICUs. Angiotensin-converting enzyme inhibitors were suspended in 28% of the Centers. The survey shows what is considered as standard monitoring in Italian Cardiac ICUs. Standard, routinely used monitoring consists of ECG, SpO2, etCO2, invasive BP, CVP, diuresis, body temperature, and BGA. It also shows that there is large variability among the various Centers regarding hemodynamic monitoring of fluid therapy and inotropes administration. Further research is required to better standardize and define the indicators to improve the standards of intensive care after cardiac surgery among Italian cardiac ICUs.

Central venous blood gas and acid-base status in conscious dogs and cats.

To determine the reference level of central venous oxygen saturation (ScvO2) and clinical efficacy of central venous blood gas analysis, partial pressures of oxygen and carbon dioxide, pH, oxygen saturation, base excess (B.E.) and HCO3 concentration were compared between simultaneously obtained central venous and arterial blood samples from conscious healthy 6 dogs and 5 cats. Comparisons between arteriovenous samples were performed by a paired t-test and Bland-Altman analysis. Between arteriovenous samples, B.E. showed good agreement, but there were significant differences in other parameters in the dogs, and no good agreement was detected in cats. The ScvO2 in dogs and cats were 82.3 ± 3.5 and 62.4 ± 13.5%, respectively. Central venous blood gas analysis is indispensable, especially in cats.

Correlation between Arterial and Central Venous Blood Gas Values in Critically Ill Patients

Manuscript History: Arterial blood gas (ABG) analysis is a commonly and golden standard performed procedure that is often used to assess the acid-base status along with adequacy of ventilation and oxygenation among predominantly critically/acutely ill patients. Unfortunately, prolonged arterial catheterization or repeated direct blood sampling from the artery is associated with rare, but serious, complications to the patient as well as the health care providers. Patients who require frequent blood gas testing often have indwelling central venous catheters for the administration of intravenous medications or the monitoring of central vascular pressures, allowing for repeated central venous blood gas (VBG) analysis. Venous blood gas analysis requires fewer punctures, is a relatively safer procedure for both the patient and health care provider, and may be alternative to ABG analysis (Walkey et al., 2010), (Lorente et al., 2006), Scheer et al., 2002), (Valentine et al., 2005).This study was aimed to determine the correlation between arterial and central venous blood gas measurements for monitoring of acid-base balance & oxygenation in the critically ill patients. Prospective comparative study of 90 samples from 45 patients with diverse medical& surgical conditions was conducted. Arterial and venous values for pressure of hydrogen (pH), partial pressure of carbon dioxide (PCO2), bicarbonate (HCO3), partial pressure of oxygen (PO2), and oxygen saturation (SO2)were obtained simultaneously from each patient. Identity plot was used to check the perfect agreement between the paired measurements. The strength of the relationship between the arterial and venous gas values was assessed with the Pearson product-moment correlation coefficient test. Arterial pH and venous pH were found to be correlated significantly (Pearson correlation coefficient r = 0.93, 95% confidence limits of r = 0.90 to 0.96, P 0.05) &(r = -0.08, 95% confidence limits of r = -0.28 - 0.13, P >0.05) respectively. Conclusion: there was a perfect correlation between the arterial and central venous measurements of acid - base (pH, PCO2, HCO3-) in the critically ill patients. While, it is difficult to conclude at least a basic agreement between the arterial and central venous measurements of oxygenation (PO2 & SO2).

Foregut reduplication cyst: Anaesthetic implications of the rare anomaly.

Sir, Congenital duplications can occur anywhere in the gastrointestinal tract and one-third of all duplications are foregut duplications.[1] A 6-month-old male child weighing 4 kg was admitted in our hospital with the history of recurrent productive cough with intermittent fever for 4 months. He was born full term by normal vaginal delivery. The child was apparently well till 2 months of age after which he started developing repeated episodes of cough and cold with fever. Child was febrile (102° F), lethargic with respiratory rate of 28-30/min. Breath sounds were markedly decreased on the right side of the chest. X-ray chest showed a homogenous opacity in mid-thoracic region compressing the right lung. The computed tomography [Figure 1] scan of chest revealed a large cystic mass (7 cm × 4 cm × 4 cm) in posterior mediastinum extending from the lung apex to base and reaching the opposite mediastinum posterior to oesophagus causing displacement of oesophagus and bronchus anteriorly. It also showed mild pleural effusion on the right side. A provisional diagnosis of foregut duplication cyst was made, and cyst excision via right thoracotomy was planned. Figure 1 Computed tomography scan of the thorax showing the cyst His pre-operative blood investigations were all normal. Once the patient arrived, monitors including electrocardiography (ECG), oxygen saturation (SpO2) and non-invasive blood pressure were placed. No sedative premedication was given. After pre-oxygenation, anaesthesia was induced with sevoflurane in graded concentration and an intravenous line secured. Intubation was performed under sevoflurane with a 4 mm uncuffed flexometallic endotracheal tube. Injection fentanyl 10 μg and injection vecuronium 0.4 mg were then given, and anaesthesia maintained with isoflurane and O2/N2O (50:50). Right internal jugular and right radial arterial cannulation were performed. Intraoperative monitoring included ECG, intra-arterial blood pressure, SpO2, nasopharyngeal temperature, end-tidal carbon dioxide, airway pressures, urine output, central venous pressure and intermittent arterial blood gas (ABG) analysis. The cyst was removed after mobilization that took 3 h. Warming mattress and radiant warmer were used to maintain normothermia. The estimated blood loss was around 300 ml, which was replaced with packed cells. Intercostal block was given with 6 ml of injection bupivacaine 0.125% and rectal suppository of paracetamol 80 mg inserted for post-operative analgesia. The patient was extubated uneventfully in the end and shifted to post-operative care unit. The post-extubation ABG was normal with pH - 7.4; pCO2-38 mmHg; HCO3-20 mmol/L; PaO2-98 mm Hg and SpO2-97% on oxygen by mask at 4 L/min. The post-operative course was uneventful, and the child was discharged after 15 days. The biopsy report later confirmed the diagnosis. Foregut malformation cysts are the second most common cause of posterior mediastinal mass after the neural tumours.[2] An embryonic defect in vacuolization of the oesophagus results in duplication and normally occurs in the 6th week of gestation.[1] The fusion anomalies of cervical and upper thoracic vertebral bodies are encountered in 80% of these cases due to the defect in their embryological development.[2] Although the mean age of onset of symptoms was 49.4 months in a study by Cohen et al., it ranges from 1 month to 18 years.[2] Most cases present with respiratory distress, which may be present from birth. Sometimes the symptoms may be delayed with sudden onset cough, wheeze or recurrent respiratory infections. In rare cases the cyst may perforate into the bronchial tree.[1] Extension of the cyst into the infradiaphragmatic area may cause gastrointestinal symptoms and extension into the neural canal can cause signs of spinal cord compression.[3] Cysts require total excision, to prevent cancer development or recurrence of symptoms.[2] The incidence of complications with the induction of anaesthesia in patients with mediastinal masses has been reported to be 7-18% including refractory cardio-respiratory collapse.[4,5] Inhalational induction with sevoflurane was chosen with a hope that the spontaneous ventilation will preserve the diaphragmatic movements in a caudal direction, and a normal transpleural pressure gradient will be maintained preventing airway collapse. Intubation was also carried out without muscle relaxants with a flexometallic tube to cause splinting of the trachea beyond the obstruction.[6,7] Successful use of femoro-femoral cardiopulmonary bypass (CPB) has been described in patients with mediastinal masses to restore the oxygenation in the event of severe life-threatening hypoxia.[4] Tempe et al. have recommended femoral vessel cannulation under local anaesthesia and CPB circuit primed and kept ready before induction of GA in symptomatic patients with a mediastinal mass.[8] Invasive haemodynamic monitoring is mandatory in these cases as severe cardiorespiratory embarrassments are noted. Good post-operative analgesia is a must after thoracotomy to hasten recovery. We used intercostal block, and rectal acetaminophen as thoracic epidural in infants is not a technique that is commonly practiced in our institution. We could successfully extubate the patient on the table after end of surgery, and he had an uneventful recovery.