Thermodilution determination of right ventricular volume and ejection fraction: a comparison with biplane angiography

In 13 patients without tricuspid incompetence, we compared the values of right ventricular ejection fraction (RVEF) and right ventricular end-diastolic volume (RVEDV) obtained with biplane angiography and thermodilution at end-inspiration. A modification of Simpson's rule was used to measure angiographic volumes, and a new pulmonary artery catheter equipped with a rapid response thermistor was used to measure the ejection fraction by the Holt plateau method. The correlation between the two methods was acceptable (r = 0.83 for RVEF, r = 0.71 for RVEDV) despite the limitations of both angiography and thermodilution. Thermodilution underestimated RVEF and overestimated RVEDV when compared to angiography. The variation coefficient with thermodilution for five measurements of the RVEF per patient was 12 +/- 5%. In addition to pressure and cardiac output measurements, monitoring of RVEF and RVEDV in the ICU should be possible with such a catheter. Further work is needed to assess the clinical relevance of these added data and their use for optimizing the therapy of right ventricular failure in acutely ill patients.     

Right ventricular function in COPD patients during weaning from mechanical ventilation

We studied the right ventricular function during a successful weaning period in 7 COPD patients without LV disease who had been mechanically ventilated for several days after an acute exacerbation of their disease. A Swan-Ganz ejection fraction thermodilution catheter performed measurements of right ventricular ejection fraction (RVEF) and right ventricular end-diastolic volume index (RVEDVI) before and fifteen minutes after disconnection from the ventilator at the maintenance FiO₂. Although pulmonary artery pressure (PAP) rose from 25±4 to 28.5±4.5 mmHg after disconnection from the ventilator, RVEF (0.36±0.56 to 0.35±0.12) and RVEDVI (117±51 to 126±52 ml/m²) remained similar in both conditions. We concluded that right ventricular systolic function assessed with modified pulmonary artery catheter was maintained during the weaning phase in such weanable patients. This method could easily detect any fall of RVEF or diastolic RV enlargement able to impair the weaning in some patients.     

Thermodilution measurement of right ventricular ejection fraction with a modified pulmonary artery catheter

In 14 critically ill patients in stable cardiopulmonary status, right ventricular ejection fraction (RVEF) was measured by thermodilution technique and by radionuclear (gated first pass) technique. The pulmonary artery catheter was equipped with a fastresponse thermistor and an intracardiac ECG monitor. In addition, the proximal lumen ended in a 3-hole port 21 cm from the tip of the catheter to facilitate mixing of the cold bolus above the tricuspid valve. The use of a new algorithm based on an exponential curve analysis of the thermodilution curve limited the variability of RVEF determinations to 7.6%. The correlation between RVEF measured by thermodilution and radionuclear techniques was significant (y= 12.7+0.49x, r=0.67, p<0.01). However, the values obtained by thermodilution were usually lower, especially for high RVEF. Nevertheless, although some discrepancy was found, thermodilution techniques allow simple, accurate and repetitive bedside measurements of right ventricular volumes in the critically ill.     

Influence of constant sustained positive airway pressure on right ventricular performance

Objective The detrimental effect of positive airway pressure on right ventricular (RV) performance is controversial and the aim of this study was to determine the effects of constant positive airway pressure without ventilatory fluctuation on RV performance with the aid of a pulmonary arterial catheter equipped with a rapid response thermistor for measuring RV ejection fraction (RVEF) and RV end-diastolic volume index (RVEDVI).Design A prospective, clinical study.Setting The central operating theatre of a university hospital.Patients Nine patients who had major surgery and required right heart catheterization for normal clinical management.Measurements and results Cold indicator was injected into the RV 4 or 5 times for each airway pressure (0, 10 or 20 cmH₂O) which was maintained manually stable for 15 s, and 9 paired data were analyzed by repeated-measures analysis of variance. They are separated into two groups; RVEF at zero airway pressure greater (A group) or less (B group) than 0.4. In A group (7 patients), increasing airway pressures (0 vs 10 vs 20 cmH₂O) did not affect RVEF (0.55±0.05 vs 0.54±0.06 vs 0.56±0.04), RVEDVI (69±36 vs 73±29 vs 58±20 ml·m^–2), or stroke volume index (SVI: 38±18 vs 40±17 vs 33±13 ml·beat^–1 ·m^–2); however, in B (2 patients), RVEF (0.35 and 0.38 vs 0.31 and 0.28 vs 0.19 and 0.17) and SVI (35 and 28 vs 32 and 27 vs 27 and 23) decreased, while RVEDVI increased (99 and 73 vs 103 and 97 vs 146 and 132).Conclusions In most patients, the changes in RVEF, SVI, and RVEDVI did not occur under constant positive airway pressure, therefore the changes reported in mechanically ventilated patients may not attributable to the extent of positive airway pressure but rather to abrupt increases in airway pressure. There appears, however, to be patients whose RV function is so disturbed that they cannot cope with increased afterloads.     

Right ventricular pressure-volume relations in chronic lung disease

Summary. Thirty-four patients with chronic lung disease in stable condition were studied at supine rest (RS), at rest with the legs raised (LR), and during two levels of exercise: El, 0 or 20 W, E2, 20 or 40 W. Five patients had normal spirometry (group 1), six patients had normal vital capacity but FEV₁/VC below 70% (group 2), and 23 patients had VC below 95% of normal and FEV₁/VC below 70% (group 3); group 3 was subdivided into group 3a (n= 14) without, and group 3b (n= 9) with a history of right heart failure (RHF). Right ventricular end-diastolic (RVEDV) and end-systolic (RVESV) volumes were computed from stroke volume and right ventricular ejection fraction (RVEF). RVEF at rest was correlated with lung function variables. Changes in RVEF from LR to E2 were normal, i.e. above 0.05, except for in group 3b, where RVEF did not increase with exercise. Relation between RVESV and pressure, and changes in stroke volume with RVEDV from LR to E2 were also abnormal in group 3b. These results show that in patients with chronic lung disease RVEF at rest reflects lung function, whereas its adaptation to exercise is impaired only in patients who have experienced RHF episodes.     

Simultaneous assessment of right ventricular ejection fraction and central haemodynamics at rest and during exercise in patients with pulmonary hypertension

Summary. In 10 patients, aged 55–73, with pulmonary hypertension, right ventricular ejection fraction (RVEF) was measured simultaneously with central haemodynamics twice, at rest and during exercise. In the first investigation, RVEF was measured with first pass (FQ) radionuclide angiocardiography using ¹³³Xe and ⁹⁹Tc^m as tracers. In the second investigation after 1 h's rest, RVEF was measured with equilibrium (EQ) radionuclide angiocardiography. Significant correlations were found between RVEF and pulmonary artery pressure (r = - 0. 76 to - 0. 88) and between RVEF and right arterial pressure (r= -0. 76 to -0. 84) at rest and during exercise. RVEF was low or decreased during exercise in all patients with haemodynamic signs of right ventricular failure. Good correlations were found between the FP and EQ techniques for measuring RVEF both at rest, r= 0.86, and during exercise, r= 0.91. RVEF, measured with the FP technique, showed better reproducibility and better correlation to haemodynamic variables and to history of right ventricular failure than the EQ technique. Thus, the FP technique seemed to be the method of choice for assessment of RVEF.     

Right and left ventricular performance during endotoxin-induced pulmonary hypertension in sheep

Summary. We investigated right and left ventricular performance by radionuclide angiocardiography in anaesthetized and instrumented sheep following a (1.5 μg/kg) sublethal Escherichia coli endotoxin infusion. Six animals served as controls and five were pre-treated with intravenous Ibuprofen (12 mg/kg). In control sheep an acute five-fold increase of pulmonary vascular resistance (PVR) resulted in a significant decrease of right ventricular ejection fraction (RVEF) and stroke volume. Left ventricular ejection fraction (LVEF) was unchanged as was pulmonary capillary wedge pressure (PCWP). The calculated right and left ventricular end-diastolic volumes (RVEDV; LVEDV) changed significantly in opposite directions during the acute increase of PVR. Right ventricular end-diastolic pressure increased significantly paralleled by an increase of RVEDV. The decrease of LVEDV with an unchanged PCWP suggested a decrease of left ventricular compliance. Pre-treatment with Ibuprofen resulted in complete cardiovascular stability after endotoxin.     

Effects of norepinephrine on right ventricular function in septic shock patients

Objective To study the effects of norepinephrine on right ventricular function in patients with hyperdynamic septic shock.Design Prospective, open study.Setting A 15 bed ICU in a university hospital.Patients 9 patients with hyperdynamic septic shock (SBP<90 mmHg, Cl4l·min^–1·m^–2, SVRI850 dynes·s·cm^–5m^–2 and oliguria).Interventions Plasma volume expansion was used to correct a suspected volume deficit and then, norepinephrine infusion was started and titrated to restore systemic blood pressure to the normal range (mean infusion rate: 1.1±0.2 mcg·kg^–1·min^–1). Norepinephrine was the only vasoactive agent used in these patients.Measurements and results A modified Swan-Ganz catheter mounted with a fast response thermistor was inserted in each patient, allowing repeated measurements of RVEDVI and RVEF. At time of inclusion to the study, all but one patient had elevated MPAP (23±4 mmHg) and RVEF50%, and all patients had RVEDVI90 ml·m^–2. During norepinephrine infusion, MAP increased from 51±9 to 89±10 mmHg (p<0.0001), PVRI increased from 204±35 to 286±63 dynes·s·cm^–5·m^–2 (p<0.05), and despite this increase in right ventricular afterload, no detrimental effect in RVEF (36±11 to 36±10%) or in RVEDVI (116±30 to 127±40 ml·m^–2) was observed. A Frank-Starling relationship for the right ventricle was constructed by plotting an index of ventricular performance (RVSWI) against an index of ventricular preload (RVEDVI). A significant upward shift to the right of the relationship was observed during norepinephrine infusion.Conclusion It was concluded that norepinephrine exerted a favourable effect on right ventricular function.Work done at Sainte Marguerite Hospital, Marseille, France     

Prostacyclin and right ventricular function in patients with pulmonary hypertension associated with ARDS

Eight patients who developed pulmonary artery hypertension during the adult respiratory distress syndrome (ARDS) were treated with an infusion of prostacyclin (PGI₂, 12.5–35.0 ng·kg^–1·min^–1) for 45 min. We examined whether reducing the right ventricular (RV) outflow pressures by PGI₂ infusion would increase the right ventricular ejection fraction (RVEF) measured by thermodilution. PGI₂ reduced the pulmonary artery pressure (PAP) from 35.6 to 29.1 mmHg (p<0.01). The cardiac index (CI) increased from 4.2 to 5.81·min^–1·m^–2 (p<0.01) partly due to an increased stroke volume. The decreased PAP together with the increased CI resulted in a fall of the calculated pulmonary vascular resistance index (PVRI, from 5.1 to 2.5 mmHg·min·m²·1^–1,p<0.01). In the patients with subnormal baseline RVEF the increased stroke volume was associated with an increased RVEF (from 47.6% to 51.8%,p<0.05) suggesting improved RV function. This result was underscored by a significant relationship between the changes in PVRI and RVEF (r=0.789, % RVEF=–2.11·PVRI-1.45). Despite an increased venous admixture from 27.8% to 36.9% (p<0.05) the arterial PO₂ remained constant resulting in an increased oxygen delivery from 657 to 894 ml·min^–1·m^–2 (p<0.01). We conclude that short term infusions of PGI₂ increased CI concomitant to improved RV function parameters when baseline RVEF was depressed. Since improved oxygen availability should be a major goal in the management of patients with ARDS PGI₂ may be useful to lower pulmonary artery pressure in ARDS.Supported by the Deutsche Forschungsgemeinschaft (grant Fa 139/2-2)     

Right ventricular ejection fraction measurement in moderate acute respiratory failure (ARF). Effects of PEEP

Eight patients mechanically ventilated for acute respiratory failure were submitted to increasing levels of PEEP, from 0 to 15 cm H₂O. Right ventricular ejection fraction (RVEF) and end-diastolic volume index (RVEDVI) were measured using the fast response thermistor Swan-Ganz catheter. PEEP induced a linear decrease of cardiac index, while the pulmonary artery pressure increased. In three patients (group A) with a RVEDVI larger than 120 ml at ZEEP, RVEF decreased and RVEDVI increased with PEEP. In the other five patients (RVEDVI>120 ml, group B), RVEF was unchanged and RVEDVI decreased at PEEP 15 cm H₂O. This study suggest that RV changes induced by PEEP are probably a function of the initial RVEF and RVEDVI.     

Comparison of two methods for enhanced continuous circulatory monitoring in patients with septic shock

Objective To compare a modified pulmonary artery catheter (PAC) and pulse-contour analysis by the PiCCO (Pulsion Medical Systems, Munich, Germany) system for continuous assessment of cardiac output in patients with septic shock. In addition, to assess the relationships between an index of global end-diastolic volume (GEDV) derived by the PiCCO system with traditional PAC-derived indicators of filling: central venous pressure; pulmonary artery occlusion pressure; and right ventricular end-diastolic volume (RVEDV). Design Prospective cohort study. Setting Surgical intensive care unit of a university hospital. Patients and participants 14 patients with septic shock. Interventions None. Measurements and results A significant correlation was found between continuous cardiac output by PAC (CCO_PAC) and by pulse-contour analysis (r ² = 0.714, p < 0.0001), accompanied by a bias of 0.1 l min⁻¹ and a precision of 2.7 l min⁻¹. The correlation between CCO_PAC and cardiac output measured by transcardiopulmonary thermodilution was also significant (r ² = 0.781, p < 0.0001). There was a bias for the two methods of 0.2 l min⁻¹, and a precision of 2.2 l min⁻¹. The GEDV showed no correlation with central venous pressure, pulmonary artery occlusion pressure, or RVEDV. Conclusion In patients with septic shock, the averaged bias in continuous measurement of cardiac output by both a modified pulmonary artery catheter and pulse-contour analysis was small, but variability was large. No correlation was found between GEDV and RVEDV. The clinical importance of different cardiac filling parameters needs further investigation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effects of inhaled nitric oxide on right ventricular function in severe acute respiratory distress syndrome

Objective To compare the effects of inhaled nitric oxide (NO) and an infusion of prostacyclin (PGI₂) on right ventricular function in patients with severe acute respiratory distress syndrome (ARDS).Design Randomized prospective short-term study.Setting: Post-surgical ICU in an university hospital.Patients 10 patients with severe ARDS referred to our hospital for intensive care.Interventions In random sequence the patients inhaled NO at a concentration of 18 parts per million (ppm) followed by 36 ppm, and received an intravenous infusion of PGI₂ (4 ng·kg^–1·min^–1).Measurement and results Inhalation of 18 ppm NO reduced the means (±SE) pulmonary artery pressure (PAP) from 33±2 to 28±1 mmHg (p=0.008), increased right ventricular ejection fraction (RVEF), as assessed by thermodilution technique, from 28±2 to 32±2% (p=0.005), decreased right ventricular end-diastolic volume index from 114±6 to 103±8 ml·m^–2 (p=0.005) and right ventricular end-systolic volume index from 82±4 to 70±5 ml·m^–2 (p=0.009). Mean arterial pressure (MAP) and cardiac index (CI) did not change significantly. The effects of 36 ppm NO were not different from the effects of 18 ppm NO. Infusion of PGI₂ reduced PAP from 34±2 to 30±2 mmHg (p=0.02), increased RVEF from 29±2 to 32±2% (p=0.02). Right ventricular end-diastolic and end-systolic volume indices did not change significantly. MAP decreased from 80±4 to 70±5 mmHg (p=0.03), and CI increased from 4.0±0.5 to 4.5±0.5 l·min^–1·m^–2 (p=0.02).Conclusions Using a new approach to selective pulmonary vasodilation by inhalation of NO, we demonstrate in this groups of ARDS patients that an increase in RVEF is not necessarily associated with a rise in CI. The increase in CI during PGI₂ infusion is probably related to the systemic effect of this substance.Supported by DFG Fa 139/1-2/2-2     

Mathematical coupling does not explain the relationship between right ventricular end-diastolic volume and cardiac output

OBJECTIVE: To evaluate the clinical significance of mathematical coupling on the correlation between cardiac output and right ventricular end-diastolic volume (RVEDV) through measurement of cardiac output by two independent techniques. DESIGN: Prospective, observational study. SETTING: Surgical intensive care unit in a level 1 trauma center. PATIENTS: Twenty-eight critically ill surgical patients who received mechanical ventilation and hemodynamic monitoring with a pulmonary artery catheter. INTERVENTIONS: A pulmonary artery catheter designed to measure right ventricular ejection fraction (RVEF) and cardiac output by the intermittent bolus thermodilution (TDCO) method and continuous cardiac output by the pulsed thermal energy technique was placed. A computerized data logger was used to collect data simultaneously from the RVEF/TDCO system and the continuous cardiac output system. MEASUREMENTS AND MAIN RESULTS: Two hundred forty-nine data sets from 28 patients were compared. There is statistical correlation between TDCO and continuous cardiac output measurements (r = 0.95, p < 0.0001) with an acceptable bias (-0.11 L/min) and precision (+/-0.74 L/min). The correlation was maintained over a wide range of cardiac outputs (2.3-17.8 L/min). There is a high degree of correlation between RVEDV and both TDCO (r = 0.72, p < 0.0001) and independently measured continuous cardiac output (r = 0.68, p < 0.0001). These correlation coefficients are not statistically different (p = 0.15). CONCLUSIONS: The continuous cardiac output technique accurately approximates cardiac output measured by the TDCO method. RVEDV calculated from TDCO correlates well with both TDCO and independently measured continuous cardiac output. Because random measurement errors of the two techniques differ, mathematical coupling alone does not explain the correlation between RVEDV estimates of preload and cardiac output.     

实时三维超声心动图评价阻塞型睡眠呼吸暂停低通气综合征患者连续气道正压通气治疗前后右心室结构及功能变化

目的 观察实时三维超声心动图(RT-3DE)评价连续气道正压通气(CPAP)治疗前后阻塞型睡眠呼吸暂停低通气综合征(OSAHS)患者右心室结构及功能变化的价值.方法 纳入50例OSAHS患者(OSAHS组)及40名健康志愿者(对照组),比较组间RT-3DE及传统超声心动图参数差异;观察OSAHS组CPAP治疗前及治疗3...     

超声心动图评价闭塞性肺血管病、右心功能及吸入一氧化氮的影响

本文报道了应用超声心动图面积－长度法评价１５例闭塞性肺血管病右心功能及吸入一氧化氮（ＮＯ）后右心功能的变化。结果表明右室舒张末期容积（ＲＶＥＤＶ）和收缩末期容积（ＲＶＥＳＶ）增加，右室每搏量（ＲＶＳＶ）、右室射血分数（ＲＶＥＦ）和右心排血量（ＲＶＣＯ）均降低。吸入ＮＯ后收缩期跨三尖瓣峰值压差平均降低２３％（Ｐ＜０．００１），ＲＶＥＤＶ和ＲＶＥＳＶ分别减小１７．７％和３７．４（Ｐ值均小于０．００１），ＲＶＳＶ、ＲＶＥＦ、ＲＶＣＯ分别增加３０．８％、５８．７％、３４．４％（Ｐ值均小于０．０１－０．００１），提示右心功能有明显改善。     

Influence of right ventricular pre‐ and afterload on right ventricular ejection fraction and preload recruitable stroke work relation

When right ventricular (RV) afterload is abnormally increased, it correlates inversely with right ventricular ejection fraction (RVEF). We tested, whether this would be different with normal afterload. Additionally, we investigated whether previous studies on the slope of RV preload recruitable stroke work (SW) relation, which used rather non‐physiological measures to change RV preload, could be transferred to more physiological loading conditions. RV volumes were determined by thermodilution in 16 patients with stable coronary artery disease and normal pulmonary artery pressure (PAP) at rest. Pre‐ and afterload were varied by body posture, nitroglycerin (NTG) application and by exercise at different body positions. At rest, the change from recumbent to sitting position decreased PAP, cardiac index (C_i), RV diastolic and systolic volumes, and RVEF. Additionally, mean pulmonary artery pressure (MPAP) correlated positively with both RVEF and cardiac index. After correction for mathematical coupling, the RV preload recruitable SW relation was: right ventricular stroke work index (RVSW_i) (10³ erg m^–2)= 8·1 × (RV end‐diastolic volume index ?4·9), with n=96, r=0·57, P≤0·001. Exercise abolished this correlation and led to an inverse correlation between RV end‐systolic volume (ESV) and RVSW. In conclusion, (i) RVEF correlates positively with RV afterload when afterload varies within normal range; (ii) the slope of the RV preload recruitable SW relation, which is obtained at steady state under normal loading conditions, is substantially flatter than previously described for dynamic changes of RV preload. With increasing afterload, preload loses its determining effect on RV performance, while afterload becomes more important. This puts earlier assumptions of an afterload independent RV preload recruitable SW relation into question.     

Evolution of right ventricular performance after CABG

34 patients scheduled for coronary artery bypass graft (CABG) surgery were studied during postoperative period. Right ventricular performance was specially performed with use of cardiac output computer REF-1 Edwards Lab., before Anaesthesia (T1) and at 6 investigation times after surgery during and after mechanical ventilation. The sixth first postoperative hours were marked by a decrease of cardiac index (2.56±0.4 to 2.41±0.4 l·mn^-1·m²) and right Ventricular Ejection Fraction (RVEF) (0.48±0.07 to 0.37±0.09). The second period was the weaning period with a further drop of RVEF (0.43±0.1 to 0.36±0.07) without change in cardiac index (2.80±0.5 l·mn^-1·m², suggesting a ventricular postoperative and weaning depression, as previously described for the left ventricle. In addition, postoperative tachycardia (Heart rate=59±9 at T1 to 95±14 at T7) may contribute to myocardial ischemia.     

实时三维超声心动图对法洛四联症手术前后右室收缩功能分析

目的 应用实时三维超声心动图(RT-3DE)检测法洛四联症(TOF)手术前后右室收缩功能.方法 30例TOF患者常规二维超声心动图检查并确诊后,使用RT-3DE采集患者的右室全容积数据库,分析右室舒张末容量(RVEDV)、收缩末容量(RVESV),计算射血分数(EF).比较术前、术后12 d、术后3个月RVEDV、RVESV及EF值的变化.结果 30例患者中20%(6/30)患者术前右室EF低于50%,术后12 d收缩末容量较术前增加(P<0.05),EF值较术前减低(P<0.05),术后3个月RVEDV较术前增大(P<0.05).常规二维超声术后复查,70%患者(21/30)残留肺动脉分支狭窄,所有患者均存在肺动脉瓣反流.结论 RT-3DE能简便、准确地确定右室容积并计算右室收缩功能;TOF患者术后残留肺动脉分支狭窄及肺动脉瓣反流可能导致右室收缩功能下降.     

Alterations in circulating vasoactive substances in the critically ill —a comparison between survivors and non-survivors

Objective Regulation of circulatory homeostasis is based on several factors including various circulating vasoactive substances. Whether these regulators differ between survivors and non-survivors was investigated in critically ill patients.Design Prospective study.Setting Clinical investigation on a surgical intensive care unit of an university hospital.Patients 60 consecutive patients suffering from trauma (n=21) or postoperative complications (n=39) were studied prospectively. The patients were divided into survivors (n=27) and non-survivors (n=33). Therapy was adjusted to the standards of modern intensive care management by physicians who were not involved in the study.Measurements and results Endothelin-1, atrial natriuretic peptide (ANP), vasopressin, renin, and catecholamine (epinephrine, norepinephrine) plasma levels were measured from arterial blood samples using radioimmunoassay (RIA) or high-pressure liquid chromatography (HPLC) technique on the day of admission to ICU and during the following 5 days. Various hemodynamic parameters were also monitored during that period. The non-survivors showed elevated pulmonary artery pressure (PAP: 34.1±5.4 mmHg) and pulmonary capillary wedge pressure (PCWP: 20.3±7.3 mmHg) already at the beginning of the study. Cardiac index (CI) did not differ among the groups, whereas right ventricular ejection fraction (RVEF) decreased in the non-survivors. PaO₂/FIO₂ decreased only in the non-survivors, whereas VO₂ increased in the survivors (from 246±48 to 331±43 ml/min). Plasma levels of renin (from 206±40 to 595±81 pg/ml) and vasopressin (from 5.78±0.82 to 7.97±0.69 pg/ml) increased significantly in the non-survivors. Epinephrine and norepinephrine plasma concentrations were elevated in the non-survivors already at baseline and tremendously increased in these patients during the following days. ANP plasma levels significantly increased also only in the non-survivors (from 188±63 to 339±55 pg/ml) (p<0.05). Endothelin-1 decreased in the survivors, whereas it significantly increased in the non-survivors (from 3.62±0.68 to 9.37±0.94 pg/ml) during the study period (p<0.05). Analyses of co-variance revealed overall no significant correlation between circulating vasoactive substances and hemodynamics.Conclusions Systemic and regional regulators of the circulation were markedly changed by critical illness. In survivors, these regulators almost normalized within the study period of 5 days, whereas in non-survivors these alterations were even aggravated. It can only be speculated whether these regulator systems were influenced by activation of various mediator systems or whether they themselves influenced the negative outcome in the non-survivors.     

Placement considerations for measuring thermodilution right ventricular ejection fractions

BACKGROUND AND METHODS: Clinical examination of right ventricular (RV) performance has been hampered by the inability to measure easily RV volumes and ejection fraction. This study was performed to examine the effects of catheter position on thermodilution RVEF measurements. Six pigs (80 to 100 kg) were instrumented with an RV thermodilution catheter in the pulmonary artery, an injectate catheter in the right atrium, an atrial pacing electrode, and a systemic arterial catheter. RVEF measurements were determined using thermodilution in two ways: a) with incremental increases in pulmonary valve to thermistor distance; and b) with incremental increases in injectate port to tricuspid valve distance. These measurements were obtained at a paced rate of 102 +/- 2 beats/min and then repeated with pacing-induced tachycardia (140 beats/min). RESULTS: There was no significant difference in thermodilution RVEF measurements with the thermistor positioned 0 to 10 cm from the pulmonary valve at either heart rate. A significant reduction in RVEF occurred with the injection port located 5 to 7 cm proximal to the tricuspid valve, with this decrease becoming more pronounced during tachycardia. CONCLUSIONS: These results demonstrate that RVEF measurements can be reliably obtained using thermodilution. In these large hearts, thermodilution RVEF measurements appear to be independent of thermistor position within the pulmonary artery. However, large distances from injectate port to tricuspid valve reduced RVEF measurements.