Continuous cardiac output monitoring after cardiopulmonary bypass: a comparison with bolus thermodilution measurement

Objective The interchangeability of continuous measurement of cardiac output (CO) with the traditional bolus method in patients after cardiopulmonary bypass (CPB) is uncertain.Design Prospective observational clinical study.Setting A 20-bed surgical ICU at a university hospital.Patients Fourteen deeply sedated, ventilated, post-cardiac surgery patients, all equipped with a pulmonary artery catheter.Interventions Six hours after the end of the CPB, 56 simultaneous bolus and continuous measurements were compared by a linear regression analysis and Bland–Altman analysis. Bolus CO was estimated by averaging triplicate injections of 10 ml room-temperature NaCl 0.9%, delivered randomly during the respiratory cycle. A stringent maximum difference of 0.55 l min^—1 (about 10% of the mean bolus measured) was considered as a clinically acceptable agreement between the two types of measurements. To be interchangeable the limits of agreement (± 2 SD of the mean difference between the two methods) should not exceed the chosen acceptable difference.Measurements and results Continuous was correlated with bolus CO, with a correlation coefficient of r² = 0.68. (p< 0.01). The Bland–Altman analysis demonstrated an objective mean bias of 0.33 ± 0.6 l min^–1 (confidence interval of –0.87 – 1.58) with 34% of measured values falling outside of the clinically acceptable limits.Conclusion Our results suggest that, in the first 6 h after CPB, continuous and bolus CO determinations are not interchangeable; one third of the values obtained by continuous CO fell outside the strict limits of clinically useful precision.Electronic supplementary material The electronic reference of this article is . The online full-text version of this article includes electronic supplementary material. This material is available to authorised users and can be accessed by means of the ESM button beneath the abstract or in the structured full-text article. To cite or link to this article you can use the above reference.This work was performed in the Surgical Intensive Care Division at the University Hospital of Geneva, Switzerland.The authors declare no conflict of interest (Financial and non-financial).     

Interleukin-10, T-lymphocytes, and cardiac output in children after ventricular septal defect repair: a pilot study

Objective To evaluate the acute inflammatory response and cardiac output in children after surgery for ventricular septal defect.Design and setting Prospective, observational study in a level III multidisciplinary neonatal and pediatric intensive care unit.Patients Ten children undergoing open-heart surgery for ventricular septal defect.Interventions All children received methylprednisolone (30 mg/kg) in cardiopulmonary bypass (CPB) prime.Measurements and results Before and after cardiopulmonary bypass, plasma interleukin-10 and tumor necrosis factor α were measured by enzyme-linked immunosorbent assay, and lymphocyte subsets in peripheral blood by flow cytometry. Relative values (post-/pre-CPB) of interleukin-10 and tumor necrosis factor α were calculated. The cardiac index (CI) was measured continuously beat-to-beat by a pulse contour analysis (PiCCO). Children above the cutoff value (median cardiac index value 3.0 l min^{– 1} m^{– 2}) were designated as the normal CI group and those below this value as the low CI group. In the normal CI group the relative values of interleukin-10 remained almost seven times higher than pre-CPB values at 24 h while in the low CI group they decreased almost to pre-CPB values. Furthermore, the normal CI group, but not the low CI group, exhibited more than threefold decrease in T-lymphocytes (lymphocyte T-cells, T-helper cells, and cytotoxic T-cells) 24 h after CPB.Conclusions Children operated on for ventricular septal defect developed either a normal or low CI. The higher relative values of interleukin-10 and lower counts of lymphocyte T-cells, T-helper and cytotoxic T-cells differentiated the normal CI group from the low CI group at 24 h after cardiopulmonary bypass.     

Variations in arterial blood pressure are associated with parallel changes in FlowTrac/Vigileo®-derived cardiac output measurements: a prospective comparison study

Introduction

The reliability of autocalibrated pressure waveform analysis by the FloTrac-Vigileo^® (FTV) system for the determination of cardiac output in comparison with intermittent pulmonary arterial thermodilution (IPATD) is controversial. The present prospective comparison study was designed to determine the effects of variations in arterial blood pressure on the reliability of the FTV system in patients undergoing coronary artery bypass grafting (CABG).

Methods

Comparative measurements of cardiac output by FTV (derived from a femoral arterial line; software version 1.14) and IPATD were performed in 16 patients undergoing elective CABG in the period before institution of cardiopulmonary bypass. Measurements were performed after induction of anesthesia, after sternotomy, and during five time points during graft preparation. During graft preparation, arterial blood pressure was increased stepwise in intervals of 10 to 15 minutes by infusion of noradrenaline and lowered thereafter to baseline levels.

Results

Mean arterial blood pressure was varied between 85 mmHg and 115 mmHg. IPATD cardiac output did not show significant changes during periods with increased arterial pressure either during sternotomy or after pharmacological manipulation. In contrast, FTV cardiac output paralleled changes in arterial blood pressure; i.e. increased significantly if blood pressure was raised and decreased upon return to baseline levels. Mean arterial blood pressure (MAP) and FTV cardiac output were closely correlated (r = 0.63 (95% confidence interval [CI]: 0.49 - 0.74), P < 0.0001) while no correlation between MAP and IPATD cardiac output was observed. Bland-Altman analyses for FTV versus IPATD cardiac output measurements revealed a bias of 0.4 l/min (8.5%) and limits of agreement from 2.1 to -1.3 l/min (42.2 to -25.3%).

Conclusions

Acute variations in arterial blood pressure alter the reliability of the FlowTrac/Vigileo^® device with the second-generation software. This finding may help to explain the variable results of studies comparing the FTV system with other cardiac output monitoring techniques, questions the usefulness of this device for hemodynamic monitoring of patients undergoing rapid changes in arterial blood pressure, and should be kept in mind when using vasopressors during FTV-guided hemodynamic optimization.     

Noninvasive assessment of exercise-related intramyocellular acetylcarnitine in euglycemia and hyperglycemia in patients with type 1 diabetes using ¹H magnetic resonance spectroscopy: a randomized single-blind crossover study

OBJECTIVE

Intramyocellular acetylcarnitine (IMAC) is involved in exercise-related fuel metabolism. It is not known whether levels of systemic glucose influence IMAC levels in type 1 diabetes.

RESEARCH DESIGN AND METHODS

Seven male individuals with type 1 diabetes performed 120 min of aerobic exercise at 55–60% of Vo_2max randomly on two occasions (glucose clamped to 5 or 11 mmol/l, identical insulinemia). Before and after exercise, IMAC was detected by ¹H magnetic resonance spectroscopy in musculus vastus intermedius.

RESULTS

Postexercise levels of IMAC were significantly higher than pre-exercise values in euglycemia (4.30 ± 0.54 arbitrary units [a.u.], P < 0.001) and in hyperglycemia (2.44 ± 0.53 a.u., P = 0.01) and differed significantly according to glycemia (P < 0.01). The increase in exercise-related levels of IMAC was significantly higher in euglycemia (3.97 ± 0.45 a.u.) than in hyperglycemia (1.71 ± 0.50 a.u.; P < 0.01).

CONCLUSIONS

The increase in IMAC associated with moderate aerobic exercise in individuals with type 1 diabetes was significantly higher in euglycemia than in hyperglycemia.Intramyocellular acetylcarnitine (IMAC) is involved in the regulation of fat and carbohydrate oxidation in skeletal muscle during moderate aerobic exercise (1). Although carnitine metabolism appears comparable in patients with type 1 diabetes and healthy control subjects (2), it is not known whether IMAC is related to variations in fuel metabolism observed during exercise under differing glycemic levels in type 1 diabetes (3). Given the controversial results from previous studies linking IMAC to increased β-oxidation (4) but also to high glycolytic flux (1), the aim of the present study was to assess exercise-related concentrations of IMAC noninvasively by ¹H magnetic resonance spectroscopy (¹H MRS) (5,6) in patients with type 1 diabetes in euglycemia and hyperglycemia.     

Persistence of pandemic influenza H1N1 virus in young patients after oseltamivir therapy in the 2009–2010 season: a comparison with seasonal H1N1 with or without H275Y mutation

Comparison of the viral persistence of pandemic H1N1 (H1N1pdm) and seasonal H1N1 with or without H275Y mutation after oseltamivir therapy has not been adequately done. Virus was isolated before and on days 4-6 from the start of oseltamivir treatment for 158 cases of seasonal (2007-2008 and 2008-2009 seasons) or pandemic (2009-2010 season) H1N1 influenza. Sequence analysis was done for each season and NA inhibition assay (IC(50)) was done in the 2009-2010 season. H275Y mutation before therapy was 0% in the 2007-2008 and 2009-2010 seasons, but 100% in the 2008-2009 season. Fever and other symptoms were noticeably prolonged after oseltamivir therapy for children with H275Y mutated seasonal H1N1 (2008-2009 season), but not in patients with seasonal H1N1 without mutation (2007-2008) or H1N1pdm (2009-2010). The viral persistence rate was significantly higher for patients 15 years or younger than for those 16 years and older with H275Y mutated seasonal H1N1 (46.2% and 10.5%, respectively) or with H1N1pdm (43.3% and 11.5%, respectively). The H275Y mutation emerged after oseltamivir treatment in 2.4% (2/82) of all patients with H1N1pdm. In two children, the H275Y mutation emerged after therapy and the IC(50) increased more than 200 fold; however, the prolongation of fever was not so prominent. In conclusion, oseltamivir was effective for fever and other clinical symptoms; however, the virus persisted longer than expected after treatment in H1N1pdm influenza-infected children in the 2009-2010 season, similar to seasonal H1N1 with H275Y mutation in the 2008-2009 season.     

The association of targeted temperature management at 33 and 36 °C with outcome in patients with moderate shock on admission after out-of-hospital cardiac arrest: a post hoc analysis of the Target Temperature Management trial

Purpose

We hypothesized that a targeted temperature of 33 °C as compared to that of 36 °C would increase survival and reduce the severity of circulatory shock in patients with shock on admission after out-of-hospital cardiac arrest (OHCA).

Methods

The recently published Target Temperature Management trial (TTM-trial) randomized 939 OHCA patients with no difference in outcome between groups and no difference in mortality at the end of the trial in a predefined subgroup of patients with shock at admission. Shock was defined as a systolic blood pressure of <90 mm Hg for >30 min or the need of supportive measures to maintain a blood pressure ≥90 mmHg and/or clinical signs of end-organ hypoperfusion. In this post hoc analysis reported here, we further analyzed the 139 patients with shock at admission; all had been randomized to receive intervention at 33 °C (TTM33; n = 71) or 36 °C (TTM36; n = 68). Primary outcome was 180-day mortality. Secondary outcomes were intensive care unit (ICU) and 30-day mortality, severity of circulatory shock assessed by mean arterial pressure, serum lactate, fluid balance and the extended Sequential Organ Failure assessment (SOFA) score.

Results

There was no significance difference between targeted temperature management at 33 °C or 36 °C on 180-day mortality [log-rank test, p = 0.17, hazard ratio 1.33, 95 % confidence interval (CI) 0.88–1.98] or ICU mortality (61 vs. 44 %, p = 0.06; relative risk 1.37, 95 % CI 0.99–1.91). Serum lactate and the extended cardiovascular SOFA score were higher in the TTM33 group (p < 0.01).

Conclusions

We found no benefit in survival or severity of circulatory shock with targeted temperature management at 33 °C as compared to 36 °C in patients with shock on admission after OHCA.