Doppler measurement of cardiac output during cardiopulmonary resuscitation.

OBJECTIVE: To estimate the cardiac output produced by external cardiac compression during standard cardiopulmonary resuscitation performed by two groups of operators with different levels of experience and training. METHODS: Cardiac output was measured by Doppler aortovelography. All patients included in the study had necropsy examinations. Only patients without evidence of pulmonary embolism, myocardial rupture, aortic valve disease, or acute depletion of the intravascular volume were included. RESULTS: 31 patients presenting to the accident and emergency department suffering from non-traumatic cardiac arrest had cardiac output measurements made during resuscitation. Eleven patients were excluded after necropsy examination. The median cardiac index for the 20 study patients was 3.2 L min-1 m-2. The cardiac output produced by massage by less experienced personnel (median 1.2 L min-1 m-2) was significantly less than that produced by those fully trained in the technique (median 3.2 L min-1 m-2; P < 0.01 95% confidence interval -2.36 to -1.29). The amount of resuscitation related trauma was no greater than in other published series. CONCLUSIONS: Differences in cardiac output during external cardiac compression are related to experience with the technique.     

婴幼儿体外循环前后血浆脑红蛋白变化实验研究

目的:观察血浆脑红蛋白在婴幼儿体外循环术后水平的变化,探讨血浆脑红蛋白在体外循环前后的差异和临床意义.方法:检测24例婴幼儿体外循环前后血浆脑红蛋白水平.结果:体外循环结束时、术后第1,2天血浆脑红蛋白水平与体外循环前比较,差异均有统计学意义(P<0.05).结论:婴幼儿体外循环术后血浆脑红蛋白水平升高,可能成为评价脑损伤的指标之一.     

Continuous measurement of cardiac output with the use of stochastic system identification techniques

The limitations of developing a technique to measure cardiac output continuously are given. Logical explanations are provided for the economic, technical, and physiologic benefits of a stochastic system identification technique for measuring cardiac output. Heat is supplied by a cathetermounted filament driven according to a pseudorandom binarsequence. Volumetric fluid flow is derived by a crosscorrelation algorithm written in the C language. In vitro validation is performed with water in a flow bench. The computed flow (y) compared with the in-line-measured flow (x) yields the linear regression y = 1.024x-0.157 (r = 0.99). The average coefficient of variation is less than 2% over a volumetric fluid flow range of 2 to 10 L/min.     

Utstein style study of cardiopulmonary bypass after cardiac arrest

Objective

The aim of this study is to describe the effect emergency cardiopulmonary bypass (CPB) for resuscitation on the survival rate of patients.

Methods

The study population was composed of persons 16 years or older who had out-of-hospital cardiac arrest and were transferred to the Sapporo Medical University Hospital from the scene between January 1, 2000, and September 30, 2004. Children younger than 16 years and persons who were dead were excluded. Data were collected according to the Utstein style. Survival rates and cerebral performance category were analyzed using χ² analysis for the patients with presumed cardiac etiology. Cardiopulmonary bypass was applied to patients who showed no response with standard advanced cardiac life support. The interval from collapse and other noncardiac etiologies were considered criteria for exclusion.

Results

Of the 919 patient medical records reviewed, CPB was performed in 92 patients. Of the 919 patients, 398 were of presumed cardiac etiology (n = 66 for CPB), 48 patients survived, and 24 patients (n = 7 for CPB) had a good cerebral outcome (cerebral performance category score 1). With CPB, the rate of survival at 3 months increased significantly (22.7% vs 9.9%, P < .05), but the rate of good cerebral outcome (10.6% vs 5.1%, P = .087) showed a positive trend.

Conclusion

The use of CPB for arrest patients was associated with reduced mortality. It did not increase good neurologic outcome significantly. Still, 7 cases with intact central nervous system would have been lost without CPB.     

Bioimpedance versus thermodilution cardiac output measurement: The bomed NCCOM3 after coronary bypass surgery

Values obtained for cardiac output (CO) were compared using thermodilution (TD) with those obtained using bioimpedance (Bi) as measured using the Bomed NCCOM3 (Revision 6) in 28 consecutive patients in the first 24h after coronary artery bypass surgery (CABS). In 46 paired measurements made in the first 12 h after CABS Bi values for CO were significantly lower than TD values, the limits of agreement between the two methods were also unacceptably large (mean Bi 4.38 (SD 1.40) l/min, mean TD 5.46 (SD 1.19) l/min, limits of agreement–3.05 to +0.89). In 55 paired measurements made after 12h (all in spontaneously breathing patients) there was no significant difference between the two methods and acceptable limits of agreement, mean Bi 5.69 (SD 1.2) l/min mean TD 5.6 (SD 1.2) l/min, limits of agreement–0.99 to +1.17). The significantly lower BiCO values obtained in the first 12h after CABS show that BiCO measurement is not consistently reliable in the intensive care setting.     

Inhaled prostacyclin and platelet function after cardiac surgery and cardiopulmonary bypass

Objective: To study the effects of 6 h inhalation of aerosolized prostacyclin (PGI₂) on platelet function.¶Design: In a prospective, double-blind, randomized study, 28 patients scheduled for elective cardiac surgery requiring cardiopulmonary bypass (CPB), received either 0.9 % sodium chloride (n = 8), PGI₂ 5 μg × ml^–1 (n = 10) or PGI₂ 10 μg × ml^–1 (n = 10) as an aerosol for 6 h postoperatively.¶Setting: Cardiothoracic intensive care unit at a university hospital.¶Interventions: All patients were studied immediately after surgery during mechanical ventilation and sedation. The PGI₂ solutions or saline were administered with a jet nebulizer.¶Measurements and results: Bleeding time and chest tube drainage were measured. Blood samples for platelet aggregation, thrombelastography (TEG) and analysis of coagulation parameters and the stable prostacyclin metabolite 6-keto-PGF₁α were obtained immediately before inhalation and after 2, 4 and 6 h of inhalation. After 6 h of PGI₂ inhalation, regardless of administered dose, there was a lower rate of platelet aggregation and a lower maximal increase in light transmission in response to adenosine diphosphate (ADP) than in the control group. The TEG variable reaction time (R) was prolonged after 4 and 6 h of inhalation in the PGI₂ group receiving 10 μg × ml^–1. There were no differences between groups with respect to bleeding time and chest tube drainage or any of the other variables examined.¶Conclusion: Inhalation of PGI₂ for 6 h in patients after cardiac surgery is associated with impaired platelet aggregation detected by in vitro techniques, with no in vivo signs of platelet dysfunction.     

Pulse contour analysis after normothermic cardiopulmonary bypass in cardiac surgery patients

Introduction  

Monitoring of the cardiac output by continuous arterial pulse contour (CO_PiCCOpulse) analysis is a clinically validated procedure proved to be an alternative to the pulmonary artery catheter thermodilution cardiac output (CO_PACtherm) in cardiac surgical patients. There is ongoing debate, however, of whether the CO_PiCCOpulse is accurate after profound hemodynamic changes. The aim of this study was therefore to compare the CO_PiCCOpulse after cardiopulmonary bypass (CPB) with a simultaneous measurement of the CO_PACtherm.     

Indocyanine green clearance after cardiac surgery: the impact of cardiopulmonary bypass

Plasma clearance of indocyanine green has recently been established as a tool to monitor hepatic function and perfusion non-invasively. Reduced indocyanine green clearance has been associated with adverse outcome in cardiac surgery patients, and cardiopulmonary bypass has been hypothesized to be one important triggering factor. We performed a prospective observational study comparing the influence of off-pump and on-pump coronary surgery on perioperative indocyanine green clearance. Twenty-five consecutive adult patients without known pre-existing hepatic diseases scheduled for off-pump coronary artery bypass grafting were evaluated for hepatic dysfunction pre- and postoperatively with serial measurements of indocyanine green plasma clearance, specific laboratory values and liver function scores. Twenty-five matched patients who underwent coronary artery bypass grafting surgery with cardiopulmonary bypass in the same period served as controls. Parameters of postoperative hepatic function, including measurements of indocyanine green plasma clearance and specific laboratory values and scores, did not differ significantly between patients undergoing off-pump coronary artery bypass grafting and patients undergoing coronary artery bypass grafting with extracorporeal circulation. In patients without pre-existing hepatic diseases, a significant influence of cardiopulmonary bypass on perioperative indocyanine green plasma clearance as well as on liver specific laboratory parameters and scores cannot be proven.     

Current ultrafiltration techniques before, during and after pediatric cardiopulmonary bypass procedures

Ultrafiltration, which is currently considered as a standard method to remove excess water administered during pediatric cardiopulmonary bypass (CPB), aims to minimize the adverse effects of hemodilution, such as tissue edema and blood transfusion. Three ultrafiltration techniques can be used before, during and after CPB procedures, including conventional ultrafiltration (CUF), modified ultrafiltration (MUF) and zero-balance ultrafiltration (Z-BUF). These methods are widely different, but they have common benefits on hemoconcentration, less requirement for blood products, and reduction of the systemic inflammatory responses (SIRS). The present review attempts to restate these ultrafiltration circuitries, application methods, end-points, and clinical impacts.     

Arterial pressure waveform derived cardiac output FloTrac/Vigileo system (third generation software): comparison of two monitoring sites with the thermodilution cardiac output

The present study was conducted to study the effect of monitoring site, radial or femoral, for arterial pressure waveform derived cardiac output using FloTrac/Vigileo system with third generation software version 3.02 during cardiac surgery. The cardiac output derived from the two sites was also compared to the pulmonary artery catheter (PAC) derived cardiac output to reevaluate the relation between them using the newer software. The effect of cardiopulmonary bypass (CPB) was also studied by doing the sub analysis before and after bypass. Forty patients undergoing coronary artery bypass surgery with cardiopulmonary bypass were enrolled in the study. Cardiac output derived from radial artery (RADCO), femoral artery (FEMCO) using FloTrac/Vigileo system with third generation software version 3.02 and cardiac output using pulmonary artery catheter (PACCO) at predefined nine time points were recorded. Three hundred and forty two cardiac output data triplets were analysed. The Bland–Altman analysis of RADCO and FEMCO revealed a mean bias of −0.28 with percentage error of 20%. The pre CPB precision of both RADCO and FEMCO was 1.25 times as that of PACCO. The post CPB precision of FEMCO was 1.2 times of PACCO while that of RADCO was 1.7 times of PACCO. The third generation of FloTrac/Vigileo system shows good correlation between the radial and femoral derived cardiac outputs in both pre and post bypass periods. The newer software correlates better to PAC derived cardiac output in the post bypass period for femoral artery than radial artery.     

Atrial natriuretic factor after cardiac surgery with cardiopulmonary bypass in children.

OBJECTIVE: To determine circulating atrial natriuretic factor (ANF) concentrations in the postoperative state and to define potential hemodynamic determinants of regional plasma ANF concentrations. DESIGN: Cohort study. SETTING: Pediatric ICU in a university hospital. PATIENTS: Twenty-two children, mean age 4.2 yrs (range 0.9 to 13.5), were studied 18 hrs after corrective surgery on cardiopulmonary bypass. The underlying cardiac malformations were ventricular septum defect (n = 5), transposition of great arteries (n = 5), tetralogy of Fallot (n = 4), pulmonary stenosis (n = 3), and miscellaneous (n = 5). INTERVENTIONS: In addition to the commonly monitored variables in postoperative cardiac patients, blood volume was estimated by the 125I albumin method, and plasma samples for radioimmunoassay determination of ANF concentrations were taken simultaneously from indwelling catheters. MEASUREMENTS AND MAIN RESULTS: Compared with normal age-matched values, plasma ANF concentrations were increased in all patients, with values tending to be highest in the left atrium, followed by systemic artery, superior vena cava, and pulmonary artery (345 +/- 158, 333 +/- 169, 311 +/- 154, and 272 +/- 160 pg/mL, respectively [mean +/- SD; NS]). Simple regression analysis demonstrated a moderate correlation between blood volume and the concentration of ANF in the superior vena cava (p less than .05). Stepwise multivariate analysis showed no significant independent predictor of plasma ANF concentrations. CONCLUSIONS: Plasma ANF concentrations are increased after open-heart surgery in children, with moderate direct correlation to blood volume. The wide scatter of increased hormone concentrations may be explained by the many factors known to influence circulating ANF concentrations, such as age, underlying disease, cardiovascular state, and drugs.     

Evaluation of heavy water for indicator dilution cardiac output measurement

We evaluated deuterium oxide (D₂O) as a tracer for cardiac output measurements. Cardiac output measurements made by thermodilution were compared with those made by indicator dilution with D₂O and indocyanine green as tracers. Five triplicate measurements for each method were made at intervals of 30 minutes in each of 9 anesthetized, mechanically ventilated goats. Cardiac output ranged between 0.68 and 3.79 L/min. The 45 data points yielded a correlation coefficient of 0.948 for the comparison of D₂O indicator dilution cardiac output measurements with thermodilution measurements and a linear regression slope of 1.046. D₂O indicator dilution measurements were biased by –0.11±0.22 L/min compared with thermodilution measurements and had a standard deviation of ±0.12 L/min for triplicate measurements. Hematocrits ranging between 20 and 50 vol% had no effect on optical density for D₂O. D₂O is more stable than indocyanine green and approximately one-tenth the price (40 cents per injection compared with $4). The basic instrumentation cost of approximately $9,000 is an additional initial expense, but provides the ability to perform pulmonary extravascular water measurements with a double-indicator dilution technique. D₂O has potential as a tracer for the clinical determination of indicator dilution cardiac output measurements and pulmonary extravascular water measurements.This study was supported by a U.S. Veterans Administration Merit Review Grant (103). Dr Schreiner is a recipient of an American Society of Anesthesiologists starter grant (1985–86). Dr Leksell is on leave from the Dept of Anesthesia, Karolinska Hospital, Stockholm, Sweden, and is supported by grants from the Swedish Medical Research Council, Karolinska Institute, Sandoz AB, and the Swedish Medical Association.     

Mechanisms of a reduced cardiac output and the effects of milrinone and levosimendan in a model of infant cardiopulmonary bypass

OBJECTIVES: A low cardiac output state is an important cause of morbidity after pediatric cardiopulmonary bypass. The objectives of our study were to define the early precipitants of the reduced cardiac output and to investigate the effects on these of milrinone and levosimendan in a model of pediatric cardiopulmonary bypass. DESIGN: Experimental study. SETTING:: Research laboratory at a university-affiliated, tertiary pediatric center. SUBJECTS: Eighteen piglets. INTERVENTIONS: Piglets, instrumented with systemic, pulmonary arterial, and coronary sinus catheters, pulmonary and circumflex arterial flow probes, and a left ventricular conductance-micromanometer-tipped catheter, underwent cardiopulmonary bypass with aortic cross-clamp and cardioplegic arrest. At 120 mins, they were assigned to control, milrinone, or levosimendan groups and studied for a further 120 mins. MEASUREMENTS AND MAIN RESULTS: In controls, between 120 and 240 mins, cardiac output decreased by 15%. Systemic vascular resistance was unchanged, but pulmonary vascular resistance increased by 19%. Systemic arterial elastance increased by 17%, indicating increased afterload. End-systolic elastance was unchanged, and coronary sinus oxygen tension decreased by 4.0 +/- 1.7 mm Hg. In animals receiving milrinone cardiac output was preserved, and in animals receiving levosimendan cardiac output increased by 14%. Both drugs prevented an increase in arterial elastance and pulmonary vascular resistance after cardiopulmonary bypass. Systemic vascular resistance decreased by 31% after levosimendan, and end-systolic elastance increased by 48%, indicating improved contractility. Both agents prevented a decrease in coronary sinus oxygen tension. CONCLUSIONS: Increased afterload, which is not matched by an equivalent elevation in contractility, contributes to the reduced cardiac output early after pediatric cardiopulmonary bypass in this model. This increase is prevented by milrinone and levosimendan. Both agents exert additional beneficial effects on pulmonary vascular resistance and myocardial oxygen balance, although levosimendan has greater inotropic properties.     

Cephalothin kinetics: before, during, and after cardiopulmonary bypass surgery.

Cephalothin kinetics was studied in 5 patients the day before (PREOP), during (SURG), and the day after (POSTOP) cardiopulmonary bypass surgery. The PREOP (114 ml/min) and SURG (94 ml/min) renal clearances were of the same order but both were less than POSTOP renal clearance (248 ml/min). Cephalothin total body clearance during operation was lower (p less than 0.01) than PREOP or POSTOP clearance, with decreased metabolic clearance the primary cause. There was reduction in cephalothin elimination throughout the surgical procedure, not only in the period of extracorporeal circulation, indicating that general anesthesia had a significant influence on drug disposition. The metabolite deacetylcephalothin was rapidly formed on all 3 days and its kinetic behavior paralleled that of the parent drug.     

Semi-continuous versus injectate cardiac output measurement in intensive care patients after cardiac surgery

Objective Commercially available semi-continuous cardiac output (SCCO) monitoring systems are based on the pulsed warm thermodilution technique. There is evidence that SCCO fails to correlate with standard intermittent bolus cardiac output (ICO) in clinical situations with thermal instability in the pulmonary artery. Furthermore, ventilation may potentially influence thermodilution measurements by enhanced respiratory variations in pulmonary artery blood temperature and by cyclic changes in venous return. Therefore, we evaluated the correlation, accuracy and precision of SCCO versus ICO measurements before and after extubation.Design Prospective cohort study.Setting Intensive care unit (ICU) of a university hospital.Patients and participants 22 cardiac surgical ICU patients.Interventions None.Measurements and results SCCO and ICO data were obtained at nine postoperative time points while the patients were on controlled mechanical ventilation. Further sets of measurements were taken during the weaning phase 20 min before extubation, and 5 min, 20 min and 1 h after extubation. SCCO and ICO measurements yielded 286 data pairs with a range of 1.8–9.9 l/min for SCCO and 1.9–9.8 l/min for ICO. The correlation between SCCO and ICO was highly significant (r=0.92;p<0.01), accompanied by a bias of –0.052 l/min and a precision of 0.56 l/min. Correlation, accuracy and precision were not influenced by the mode of respiration.Conclusions Our results demonstrate excellent correlation, accuracy and precision between SCCO and ICO measurements in postoperative cardiac surgical ICU patients. We conclude that SCCO monitoring offers a reliable clinical method of cardiac ouput monitoring in ICU patients following cardiac surgery.     

Time-course of impairment of respiratory mechanics after cardiac surgery and cardiopulmonary bypass.

OBJECTIVE: Cardiopulmonary bypass (CPB) is associated with abnormalities of lung function characterized by an increase in static elastance of the respiratory system. We examined the following: a) the effects of CPB on the total inspiratory volume-pressure (V-P) relationship of the respiratory system; b) the relative contribution of the chest wall and lung to the impairment of respiratory system mechanics; and c) the time-course of such impairment. DESIGN: Prospective, interventional study. SETTING: Surgical and medical intensive care units in a teaching hospital. PATIENTS: Eight adult patients scheduled for elective open heart surgery to correct valvular dysfunction. INTERVENTIONS: V-P curves (interrupter technique) of the respiratory system were partitioned between the chest wall and lung by measurements of esophageal pressure. Measurements were obtained before sternotomy (control), immediately after, 4 hrs after, and 7 hrs after separation from CPB. MEASUREMENTS AND MAIN RESULTS: Control V-P relationships of the respiratory system and lung showed lower inflection points (Pflex) at pressure values of 5.9+/-2.3 and 4.3+/-2.5 cm H2O, respectively. Immediately after and 4 hrs after separation from CPB, both curves had sigmoid shapes because of lower Pflex and formation of upper inflection (UIP) points. The pressures corresponding to the Pflex increased significantly (p < .001) by 56%+/-3% and 78%+/-4%, whereas the UIP corresponded to a pressure value of 42.34+/-8.5 and 35.6+/-7.8 cm H2O in the respiratory system and lung, respectively. A linear V-P relationship of the chest wall was observed during the control condition and after separation from CPB. Four hours later, no further increases in the pressure values corresponding to Pflex were observed on the inspiratory V-P curves of the respiratory system and lung, whereas the UIP occurred at a pressure of 35.6+/-9.1 and 29.7+/-8.4 cm H2O, respectively. A UIP was present on the V-P curve of the chest wall at a volume of 0.77+/-0.02 L. Seven hours after separation from CPB, the inspiratory V-P curves of the respiratory system, chest wall, and lung returned to normal. CONCLUSIONS: Sternotomy and CPB produced immediate changes in lung mechanics. Chest wall mechanics were affected only 4 hrs after sternotomy. Seven hours after disconnection from CPB, all mechanics had returned to normal.     

Inflammatory response of neutrophil granulocytes and monocytes after cardiopulmonary bypass in pediatric cardiac surgery

OBJECTIVE: To determine whether the activation state of polymorphonuclear neutrophils (PMNs) and monocytes contributes to the inflammatory response after cardiopulmonary bypass (CPB) in pediatric cardiac surgery. DESIGN: Observational prospective clinical study. SETTING: Pediatric intensive care unit of a university hospital. PATIENTS: Twenty pediatric patients before and after open heart surgery with CPB. MEASUREMENTS: Cell counts of circulating PMNs and monocytes as well as phenotypic and functional analysis of these cells, and plasma levels of myeloperoxidase. RESULTS: Levels of myeloperoxidase (a marker of PMN degranulation) were significantly elevated after CPB (2.9+/-1.6 ng/ml before CPB versus 13.7+/-6.5 ng/ml after CPB, p=0.0001). However, PMN function, as measured by surface expression of CD11b/CD18 and phagocytic respiratory burst, was reduced. In contrast, the phagocytic respiratory burst of circulating monocytes was increased in some patients and there was a correlation with the increase of monocyte cell count after CPB (r=0.63, p=0.015). CONCLUSIONS: After the end of CPB, there was an ongoing inflammatory process. In particular, there was an activation of monocytes after the end of CPB.     

体外循环术后室性心律失常应用胺碘酮与利多卡因后血液动力学及临床疗效观察

目的 观察胺碘酮与利多卡因对体外循环术后室性心律失常的疗效及对血流动力学的影响.方法 体外循环术后并发室性心律失常患者87例,分为胺碘酮组(A组)42例和利多卡因组(L组)45例,分别予以胺碘酮及利多卡因治疗,持续心电监护,观察用药前后有创平均动脉压(MAP)、心率(HR)和中心静脉压(CVP)变化,比较临床疗效.结果 胺碘酮组总有效率92.86%,利多卡因组总有效率78.78%,差异有显著性意义(χ2=3.89,P<0.05);两组MAP、HR、CVP值比较,差异均无显著性意义(P>0.05).结论 胺碘酮治疗体外循环术后并发室性心律失常的有效率高于利多卡因,二者对血流动力学的影响差异小.     

Plasma fibronectin depletion after cardiac surgery in children with or without cardiopulmonary bypass

Plasma fibronectin depletion decreases resistance to sepsis. After cardiac surgery, septic complications occur more frequently when the surgical procedure is managed with a cardio-pulmonary bypass than when it is not. To determine whether cardio-pulmonary bypass produces a greater decrease in plasma fibronectin than surgery without cardio-pulmonary bypass, we studied plasma fibronectin concentrations in two groups of children operated for congenital heart diseases. Group I: 10 children undergoing surgery with cardio-pulmonary bypass. Group II: 11 children undergoing surgery without cardio-pulmonary bypass. Plasma fibronectin was monitored pre-operatively (t 1) and post-operatively at the 6th hour (t 2), 1st (t 3) and 7th (t 4) days. In both groups, plasma fibronectin concentration dropped at (t 2) and (t 3) and rose again at (t 4). There was no significant difference in plasma fibronectin levels between the two groups at any time. We conclude that the plasma fibronectin decline alone cannot explain why septic complications after surgery are more frequent with cardio-pulmonary bypass than without.