Comparison between cardiac output measured by thermodilution technique and calculated by O2 and modified CO2 Fick methods using a new metabolic monitor

Objective: To calculate cardiac output from dual oximetry with carbon dioxide production (VCO₂) and oxygen consumption (VO₂) measured by a new metabolic monitor, and to compare these values with measurements made simultaneously using the thermodilution method during the steady state condition. Design: Prospective, comparative clinical study. Setting: The adult postsurgical intensive care unit (ICU) of a University Hospital. Patients: Twenty mechanically ventilated postsurgical patients (70.7 ± 7.8 years of age; range 50–84). Measurements and results: A new metabolic monitor (Puritan-Bennett 7250, Carlsbard, USA) connected to a ventilator (Puritan-Bennett 7200) was used to measure VCO₂ and VO₂. Measurements of arterial (SaO₂) and mixed venous (SvO₂) oxygen saturations were made using pulse and venous fiberoptic oximeters. Cardiac output starting from VCO₂ (CO_VCO2) was obtained according to Mahutte's formula: CO_VCO2 = VCO₂/[k (SaO₂− SvO₂)], where k represents a constant. The value for each patient was determined from the initial measurements of thermodilution cardiac output (COtd), VCO₂, SaO₂ and SvO₂. CO_VCO2 calculated from the previous equation was compared to the COtd. Cardiac output calculated from the traditional O₂ Fick equation (CO_VO2) was compared to the COtd. All patients were studied over a period of 120 min at 15-min intervals in reasonably stable conditions. CO_VCO2 was closely related to COtd (r = 0.94; SEE = 0.79; p = 0.0001; n = 180) with a bias of − 0.10 and a precision of 0.45 l/min. The mean percent difference between the two methods was − 2.2 ± 8.3 %. CO_VO2 was related to COtd (r = 0.77; SEE = 0.79; p = 0.0001; n = 180) with a bias of − 0.57 and precision of 0.86 l/min. The mean percent difference between the two methods was − 10.8 ± 16.0 %. Conclusions: In stable patients, cardiac output measurements obtained from dual oximetry with VO₂ and VCO₂ measured by this new metabolic monitor, show good correlation with measurements made using the thermodilution method. The values of cardiac output calculated from VCO₂ are more accurate and precise than values from VO₂. The validity of these measurements in hemodynamically unstable patients and during various modes of mechanical ventilation seems warranted. Received: 5 February 1997 Accepted: 16 June 1997     

Partial CO2 rebreathing indirect Fick technique for non-invasive measurement of cardiac output

Objective.Evaluation in animals of a non-invasive and continuous cardiac output monitoring system based on partial carbon-dioxide (CO₂) rebreathing indirect Fick technique. Methods.We have developed a non-invasive cardiac output (NICO) monitoring system, based on the partial rebreathing method. The partial rebreathing technique employs a differential form of the Fick equation for calculating cardiac output (Q_T) using non-invasive measurements. Changes in CO₂ elimination (ΔVCO₂) and partial pressure of end-tidal CO₂ (Δ PETCO₂) in response to a brief period of partial rebreathing are used to measure pulmonary capillary blood flow (Q_PCBF). A non-invasive estimate of anatomic and intrapulmonary shunt fraction (Q_S/Q_T), based on oxygen saturation from pulse oximetry (SpO₂) and inspired oxygen concentration (FIO₂), is added to compute total cardiac output [Q_T=Q_PCBF/(1−Q_S/Q_T)]. The performance of the NICO was compared with iced 5% dextrose bolus thermodilution cardiac output (TDco) measurements in 6 dogs. Cardiac output was varied using dobutamine, and halothane, and by clamping of the inferior vena cava. Two hundred and forty-six (n = 246) paired measurements of TDco and NICO over a range of cardiac outputs (TDco range = 0.60–8.87 l/min) were compared using Bland-Altman analysis and weighted correlation coefficient. Results.The Bland–Altman technique yielded a NICO precision of ± 0.70 l/min (13.8%) with a mean bias of −0.07 l/min (−1.4%) compared to TDco. The weighted correlation coefficient between TDco and NICO values was: r= 0.93 (n= 246). Conclusion.The partial CO₂ rebreathing technique for measurement of cardiac output is non-invasive, automated, and based on the well accepted Fick principle. The limits of agreement between NICO and TDco is within the recommended value for NICO to be a clinically acceptable method for cardiac output measurement. The results of this canine study show that NICO performed as well, and in some cases better, than other currently available non-invasive cardiac output techniques over a wide range of cardiac outputs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Non-invasive measurement of cardiac output: whole-body impedance cardiography in simultaneous comparison with thermodilution and direct oxygen Fick methods

Objective: To determine the reliability of whole-body impedance cardiography (ICG_WB), with electrodes attached to wrists and ankles, in the measurement of cardiac output (CO) on the basis of simultaneous comparison with thermodilution (TD) and direct oxygen Fick (Fick) methods. Design: Prospective clinical study. Setting: A surgical intensive care unit at a university hospital. Patients: Thirty consecutive subjects undergoing a coronary artery bypass surgery were investigated preoperatively. Measurements: ICG_WB derived CO was measured simultaneously with the TD and Fick methods to establish the biases and limits of agreement (LA) between the methods. Results: The results obtained by ICG_WB and the invasive methods showed good agreement. The bias and LA between CO_TD and CO_ICG were 0.00 l/min; –1.37 and 1.37 l/min, respectively, and were close to those obtained between CO_TD and CO_FICK, 0.32 l/min; 1.74 and –1.10 l/min. The bias and LA between the CO_FICK and CO_ICG were –0.32 l/min; –2.24 and 1.60 l/min respectively. The repeatability value of consecutive single measurements for ICG_WB (RV_ICG = 0.57 l/min) was much better than for the TD method (RV_TD = 1.10 l/min). Conclusion: There was close agreement between the results of the three methods in the measurement of CO. In sedated preoperative patients the accuracy of ICG_WB is within clinically acceptable limits and its repeatability is excellent. ICG_WB provides a useful alternative to the TD and Fick methods in cases where the pressures supplied by the pulmonary artery catheter are not essential. Received: 19 February 1997 Accepted: 14 August 1997     

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.     

Continuous measurement of cardiac output by the Fick principle in infants and children: Comparison with the thermodilution method

Objective To compare a system that continuously monitors cardiac output by the Fick principle with measurements by the thermodilution technique in pediatric patients.Design Prospective direct comparison of the above two techniques.Setting Pediatric intensive care unit of a university hospital.Patients 25 infants and children, aged 1 week to 17 years (median 10 months), who had undergone open heart surgery were studied. Only patients without an endotracheal tube leak and without a residual shunt were included.Methods The system based on the Fick principle uses measurements of oxygen consumption taken by a metabolic monitor and of arterial and mixed venous oxygen saturation taken by pulse- and fiberoptic oximetry to calculate cardiac output every 20 s.Interventions In every patient one pair of measurements was taken. Continuous Fick and thermodilution cardiac output measurements were performed simultaneously, with the examiners remaining ignorant of the results of the other method.Results Cardiac output measurements ranged from 0.21 to 4.55 l/min. A good correlation coefficient was found:r ²=0.98;P<0.001; SEE=0.14 l/min. The bias is absolute values and in percent of average cardiac output was –0.05 l/min or –4.4% with a precision of 0.32 l/ min or 21.3% at 2 SD, respectively. The difference was most marked in a neonate with low cardiac output.Conclusion Continuous measurement of cardiac output by the Fick principle offers a convenient method for the hemodynamic monitoring of unstable infants and children.     

Frequently repeated fick cardiac output measurements during anesthesia

A computer-based system was developed for monitoring cardiac output using the Fick principle during general anesthesia. The variables of the oxygen-consumption Fick equation were measured using the following system: oxygen uptake by an originally developed respiratory gas monitoring system, arteriovenous oxygen saturation difference by pulse and fiberoptic oximetry, and hemoglobin concentration by an in vitro oximeter. Fick cardiac output and systemic vascular resistance were calculated every 30 seconds. Fick cardiac output was compared with thermodilution cardiac output in 11 anesthetized patients. A total of 208 corresponding cardiac output measurements showed a range of 2 to 9 L · min^-1. The correlation coefficient between the thermodilution and Fick cardiac outputs was 0.961, with a regression equation of Fick cardiac output = 1.058 thermodilution cardiac output 0.359. The difference between the thermodilution and Fick cardiac outputs was 0.103 ± 0.395. The Fick cardiac output was significantly lower than the thermodilution cardiac output, especially in the low flow range. We demonstrated that this new monitoring system was clinically feasible and sufficiently accurate, under the limited circumstances of our study. The integration of routinely used equipment has made possible a frequently repcatable method for estimating cardiac output in patients.     

A meta-analysis of studies using bias and precision statistics to compare cardiac output measurement techniques

Introduction. Bias and precision statistics have succeeded regression analysis when measurement techniques are compared. However, when applied to cardiac output measurements, inconsistencies occur in reporting the results of this form of analysis. Methods. A MEDLINE search was performed, dating from 1986. Studies comparing techniques of cardiac output measurement using bias and precision statistics were surveyed. An error-gram was constructed from the percentage errors in the test and reference methods and was used to determine acceptable limits of agreement between methods. Results. Twenty-five articles were found. Presentation of statistical data varied greatly. Four different statistical parameters were used to describe the agreement between measurements. The overall limits of agreement in studies evaluating bioimpedance (n = 23) was ±37% (15–82%) and in those evaluating Doppler ultrasound (n = 11) ±65% (25–225%). Objective criteria used to assess outcome were given in only 44% of the articles. These were (i) limits of agreement approaching ±15–20%, (ii) limits of agreement of less than 1 L/min, and (iii) more than 75% of bias measurements within ±20% of the mean. Graphically, we showed that limits of agreement of up to ±30% were acceptable. Conclusions. When using bias and precision statistics, cardiac output, bias, limits of agreement, and percentage error should be presented. Using current reference methods, acceptance of a new technique should rely on limits of agreement of up to ±30%.     

Clinical validation of cardiac output measurements using femoral artery thermodilution with direct Fick in ventilated children and infants

Objective: To validate clinically cardiac output (CO) measurements using femoral artery thermodilution in ventilated children and infants by comparison with CO estimated from the Fick equation via a metabolic monitor. Design: Prospective, comparison study. Setting: Paediatric intensive care unit of a university hospital. Patients: 24 ventilated infants and children, aged 0.3 to 175 months (median age 19 months). Interventions: Oxygen consumption measurements were made and averaged over a 5-min period, at the end of which arterial and mixed venous blood samples were taken and oxygen saturations measured by co-oximetry, with CO being calculated using the Fick equation. Over this 5-min period, five sets of femoral arterial thermodilution (FATD) measurements were made and averaged. One comparison of CO values was made per patient. Results: Mean Fick CO was 2.55 l/min (range 0.24 to 8.71 l/min) and mean FATD CO was 2.51 l/min (range 0.28–7.96 l/min). The mean bias was 0.03 l/min (95 % confidence interval –0.07 to 0.14 l/min), with limits of agreement of –0.45 to 0.52 l/min. When indexed to body surface area, the mean Fick cardiac index became 3.51 l/min per m² (1.52–6.98 l/min per m²) and mean FATD 3.49 l/min per m² (1.74–6.84 l/min per m²). The mean bias was 0.02 l/min per m² (95 % confidence interval –0.11 to 0.15 l/min per m²) with limits of agreement of –0.57 to 0.61 l/min per m². The mean FATD coefficient of variation was 5.8 % (SEM 0.5 %). Conclusions: FATD compares favourably with Fick derived CO estimates in infants and children and may represent an advance in haemodynamic monitoring of critically ill children. Received: 7 March 1997 Accepted: 1 July 1997     

Validation of the acetylene rebreathing method for measurement of cardiac output at rest and during high-intensity exercise

The use of the acetylene rebreathing method to estimate cardiac output (CO) during high-intensity exercise, which may be influenced by recirculation of acetylene, has not been validated. This study was designed to validate the acetylene rebreathing method to measure CO during high-intensity exercise using the direct Fick method. CO was measured at rest and during exercise at 25%, 50%, 75% and 90% of the nine subjects maximum oxygen uptake (VO _2max) by the direct Fick and acetylene rebreathing method. CO measured by the acetylene rebreathing method correlated with work rate (r=0·90, P<0·01) and with oxygen uptake (r=0·94, P<0·01). The correlation coefficient of CO between both methods was r=0·91 (P<0·01). There was no significant difference in CO measured by each method at rest as well as at each work rate. The difference in CO between each method was greater at lower CO than at higher CO. At 90% of VO _2max, the CO measured by acetylene rebreathing was nearly identical to that measured by the Fick method. It can be concluded that acetylene rebreathing for measurement of CO is valid not only at rest but also during exercise, especially during high-intensity exercise.     

Noninvasive cardiac output determined with a new method based on gas exchange measurements and carbon dioxide rebreathing: A study in animals/pigs

A system has been designed to determine cardiac output noninvasively. The system's main component is a closed breathing circuit and it measures oxygen uptake (Vo ₂), carbon dioxide elimination (Vco ₂), and end-tidal CO₂ partial pressure (Pet). As an integral part of the system, periods of CO₂ rebreathing can be automatically implemented. The CO₂ partial pressure of oxygenated mixed venous blood (Pv) is obtained from the measured exponential rise of thePet value during such a CO₂ rebreathing maneuver. A new method is described for estimating the pulmonary blood flow, alveolar ventilation, cardiac output (CO), and mixed venous oxygen saturation (Svo ₂) fromPv,Pet,Vo ₂,Vco ₂, tidal volume, and arterial oxygen saturation. The method was evaluated in 6 anesthetized and mechanically ventilated pigs. A wide range of cardiac output, shunt fractions, and dead space to tidal volume ratios were induced by combinations of bronchoalveolar lavage, hypervolemia, hypovolemia, and variable levels of positive end-expiratory pressure (PEEP). The bias between the CO obtained with the noninvasive technique (CO L/min) and the thermodilution CO (Qt L/min) was 0.13 L/min (SD=0.78 L/min) and the correlation was N=64; R=0.92; CO=0.95*Qt+0.38. The bias obtained for double determinations with the noninvasive CO technique was 0.3 L/min (SD=0.5 L/min). The bias between the noninvasive estimates ofSvo ₂ and the directly measured values was 1.1% (SD=9.3%). For double determination with the noninvasive technique the bias was -0.9% (SD=4.7%). It is concluded that in mechanically ventilated pigs the proposed method produces good estimates of CO andSvo ₂ also in the presence of significant ventilation/perfusion mismatch.     

Noninvasive cardiac output determined with a new method based on gas exchange measurements and carbon dioxide rebreathing: A study in animals/pigs

A system has been designed to determine cardiac output noninvasively. The system's main component is a closed breathing circuit and it measures oxygen uptake (Vo ₂), carbon dioxide elimination (Vco ₂), and end-tidal CO₂ partial pressure (Pet). As an integral part of the system, periods of CO₂ rebreathing can be automatically implemented. The CO₂ partial pressure of oxygenated mixed venous blood (Pv) is obtained from the measured exponential rise of thePet value during such a CO₂ rebreathing maneuver. A new method is described for estimating the pulmonary blood flow, alveolar ventilation, cardiac output (CO), and mixed venous oxygen saturation (Svo ₂) fromPv,Pet,Vo ₂,Vco ₂, tidal volume, and arterial oxygen saturation. The method was evaluated in 6 anesthetized and mechanically ventilated pigs. A wide range of cardiac output, shunt fractions, and dead space to tidal volume ratios were induced by combinations of bronchoalveolar lavage, hypervolemia, hypovolemia, and variable levels of positive end-expiratory pressure (PEEP). The bias between the CO obtained with the noninvasive technique (CO L/min) and the thermodilution CO (Qt L/min) was 0.13 L/min (SD=0.78 L/min) and the correlation was N=64; R=0.92; CO=0.95*Qt+0.38. The bias obtained for double determinations with the noninvasive CO technique was 0.3 L/min (SD=0.5 L/min). The bias between the noninvasive estimates ofSvo ₂ and the directly measured values was 1.1% (SD=9.3%). For double determination with the noninvasive technique the bias was -0.9% (SD=4.7%). It is concluded that in mechanically ventilated pigs the proposed method produces good estimates of CO andSvo ₂ also in the presence of significant ventilation/perfusion mismatch.     

Comparison of a pulse oximeter with an ear oximeter and an in-vitro oximeter

A pulse oximeter was compared with an ear oximeter for measurement of arterial hemoglobin saturation within the range of 70 to 100% in 11 healthy volunteer subjects. Two hundred seventy-seven pooled data points were obtained, and analysis was performed by means of linear regression. The accuracy was 3% (95% confidence limits). The pulse oximeter was also compared with an in-vitro oximeter, and accuracy was within 2%. The pulse oximeter was easy to use because, unlike the ear oximeter, it reqired no time-consuming instrument calibration or site preparation. In addition, the delays involved in taking an invasive sample, transporting it to the blood gas laboratory, and waiting for the results were eliminated. Saturation values were continually available, and placement and use ot the pulse oximeter sensor caused no discomfort to the volunteer subjects.     

Does measurement of systolic blood pressure with a pulse oximeter correlate with conventional methods?

The pulse oximeter is commonly used in the operating room. We evaluated the use of a pulse oximeter to monitor systolic blood pressure in 20 healthy volunteers and 42 anesthetized patients. We compared the pulse oximeter method of measuring systolic blood pressure with the cuff methods using Korotkoff sounds and Doppler ultrasound as well as with direct pressure measurement through an intraarterial cannula. Systolic blood pressure values obtained by pulse oximeter correlated well with values obtained by other conventional methods. The best correlation was found with Doppler ultrasound (r = 0.996) and the worst with arterial cannulation (r = 0.880). We conclude that this method can be used intraoperatively to measure systolic blood pressure.     

肺内分流量对部分CO2重复吸入法测定心输出量的影响

目的探讨部分CO2重复吸入法测定危重病患者心输出量的准确性及肺内分流量对其影响.方法26例机械通气患者接无创心输出量监测仪(NICO监测仪),利用部分CO2重复吸入法测定心脏指数(CINICO),同时置入肺动脉漂浮导管,以热稀释法测定心脏指数(CITD).公式法与NICO监测仪同时计算肺内分流量并进行比较.公式法计算的肺内分流量≤15%的患者为低分流组,＞15%为高分流组.结果低分流组(n=16)NICO监测仪计算的肺内分流量与公式法测定的肺内分流量无显著差异;CINICO与CITD相关性良好(r=0.91,P＜0.01),CINICO为(2.24±0.42)L/(min·m2),CITD为(2.25±0.40)L/(min·m2),两者差异无显著性.高分流组(n=10)NICO监测仪计算的肺内分流量明显低于公式法计算的肺内分流量(P＜0.01);CINICO与CITD亦显著相关(r=0.81,P＜0.01),但CINICO明显低于CITD(P＜0.01),两者分别为(2.56±0.64)L/(min·m2)和(2.87±0.64)L/(min·m2).结论CINICO与CITD相关性良好,肺内分流量是影响CINICO准确性的重要因素.     

Effect of heparinization of catheters on pulmonary artery oximetry

A clinical study was performed in two phases to determine whether pulmonary artery oximeter catheters that were impregnated or bonded with heparin would affect the accuracy of measurements of in vivo mixed venous oxygen saturation (S O₂). In phase 1, 40 patients were catheterized with either a heparin-impregnated or a plain pulmonary artery catheter. Blood was sampled at random times to correlate in vivo with in vitro S O₂ measurements. In phase 2, 16 patients who were not receiving systemic heparin therapy or aspirin and who had no coagulopathies were catheterized with either a heparin-bonded or a plain pulmonary artery catheter in a blinded order. In phase 1, a total of 364 blood samples were obtained from 40 patients. Linear regression analysis of the pooled data demonstrated y=0.98x–0.01,r=0.93,P<0.001, andn=141 with heparin-impregnated catheters; and y=0.87x+8.0,r=0.81,P<0.001, andn=223 with plain catheters. The mean difference (in vivo minus in vitro) revealed a similar error (–1.3±0.4 versus –1.4±0.4, respectively, mean±SE). The 95% confidence limits of an individual value (±8.1 versus ±12.3) suggested slightly greater accuracy with heparin-impregnated catheters. In phase 2, a total of 134 blood samples were obtained from 16 patients. Linear regression analysis showed nearly equal performance with heparin-bonded and plain catheters (r=0.97 versusr=0.98, respectively) with similar slopes (1.0 versus 1.1, respectively) but different intercepts (–0.6 versus –8.4, respectively). Analysis of the mean difference revealed a measurement error of 0.4±0.3 versus –1.3±0.3 with similar 95% confidence limits of individual values (±5.0 versus ±4.8, respectively). These differences do not appear clinically important. These data suggest that heparinization only minimally enhanced accuracy with a pulmonary artery oximetry system, which accurately measured S O₂ to within 3 to 4% of true values.     

Impact of anaesthesia-surgery on D-dimer concentration and end-tidal CO2 and O2 in patients undergoing surgery associated with high risk for pulmonary embolism

BACKGROUND: The exhaled end-tidal CO2/O2 ratio and the D-dimer concentration are diagnostic markers of pulmonary embolism (PE). OBJECTIVE: To develop a non-invasive technique to monitor for PE in surgical patients. We examine the change imparted by anaesthesia-surgery on the end-tidal CO2/O2 compared with the D-dimer. METHODS: We enrolled 125 participants undergoing an orthopaedic or oncological operation thought to confer high risk for postoperative PE. We obtained preoperative blood samples in the anaesthesia clinic, and breath samples in the preoperative holding area on the same day of surgery; we repeated blood and breath samples on the postoperative day of discharge. Blood samples were immediately analysed for fibrinogen and D-dimer (Vidas; bioMérieux, Durham, NC, USA) concentrations. Breath samples were obtained from 1 min of spontaneous tidal breaths delivered via mouthpiece while the participant breathed room air. All participants had follow-up at 30 days. RESULTS: We enrolled 125 participants and had complete data in 104. No participant developed PE or deep venous thrombosis within 30 days. The mean preoperative D-dimer was 927 +/- 928 ng ml(-1), and the mean postoperative D-dimer was 1879 +/- 1263 ng ml(-1) and the mean relative change was +234 +/- 292%. The mean preoperative end-tidal CO2/O2 was 0.31 +/- 0.05 and the mean postoperative end-tidal CO2/O2 was 0.32 +/- 0.07 and the mean relative change was +1.6 +/- 20%. The increase in D-dimer did not correlate with the increase in fibrinogen (r2 = 0.015). CONCLUSIONS: The stress impact of anaesthesia-surgery causes less change in end-tidal CO2/O2 compared with the D-dimer. Further work will be required to determine if end-tidal CO2/O2 can be used to monitor for postoperative PE.     

老年冠心病患者腹腔镜胆囊切除术中CO2气腹对心率变异性的影响及星状神经节阻滞对气腹的干预作用

【目的】观察老年冠心病患者在腹腔镜胆囊切除术（TVLC）中CO2气腹对心率变异性的影响以及术前经右侧星状神经节阻滞对CO2气腹的干预作用。【方法】选择2008年5月至2008年12月择期在全麻下行TVLC的老年冠心病患者60例。随机分为两组,对照组和右侧星状神经节阻滞组（R-SGB组）各30例。分别于麻醉后SGB前（T0）、SGB后（T1）、气腹后10min（T2）、20min（T3）和30min（T4）记录HR、MAP并分析患者的心率变异性（heart rate variability,HRV）。HRV通过功率谱分析：低频率（LF）,高频率（HF）,LF／HF比率,总能量（TP）。【结果】CO2气腹后老年冠心病患者LF、LF／HF、TP均升高（P〈0．05）。R-SGB组气腹后各时点LF、LF／HF、TP升高低于对照组（P〈0．05）。两组HF未见明显改变（P〉0．05）。【结论】CO2气腹使老年冠心病患者交感神经活性显著升高,右侧星状神经节阻滞可减轻CO2气腹时的心血管反应,维持CO2气腹时的交感／迷走神经张力的均衡。