Changes In Central Venous Pressure Research Articles

Case 4—2002 Near-fatal pulmonary embolism in the immediate postoperative period after off-pump coronary artery bypass graft surgery

A 72-year-old man with known coronary artery disease (exertional angina and 2 previous myocardial infarctions) was admitted to the hospital with a new non–Q-wave myocardial infarction as evidenced by elevated serum troponin concentration and non–Q-wave electrocardiogram changes in the anteroseptal leads. Acute management included intravenous nitrate therapy and subcutaneous enoxaparin, 80 mg twice a day; and long-term cardiac medications, including aspirin, furosemide, isosorbide mononitrate, atenolol, and ramipril, were continued. Thrombolytic therapy was not administered on this occasion. Relevant medical history included noninsulin-dependent diabetes mellitus and a dual-chamber pacemaker (Pacesetter Paragon III; St Jude Medical, St. Paul, MN), which was inserted 5 years previously for symptomatic bradycardia. The patient underwent a subsequent exercise stress test using a modified Bruce protocol. Electrocardiogram changes showed anterior ST depression at 7 minutes. He was referred for coronary angiography, which revealed significant stenosis of the left mainstem (60%), proximal anterior descending (99%), and midcircumflex (60%) coronary arteries. The right coronary artery had minor plaques in the midvessel only. Left ventricular function was preserved on ventriculography. Two hours after coronary angiography, the patient suffered further episodes of angina pectoris that responded to intravenous nitrate therapy. This condition was associated with 2 episodes of collapse on standing. The attending physician noted symptomatic bradycardia and attributed it to the vasodilatory effects of nitrate therapy. In view of his further chest pain, an intravenous infusion of unfractionated heparin was started at 12 U/kg/h. The heparin was titrated to maintain an activated partial thromboplastin ratio of twice control and was continued until surgery. The patient’s pacemaker function was not tested preoperatively, and he did not undergo a preoperative transthoracic echocardiography examination. Off-pump coronary artery bypass graft (OP-CAB) surgery was done the next day using the Octopus (Medtronic Inc, Minneapolis, MN) stabilizing device. Monitoring included electrocardiogram, peripheral oxygen saturation, end-tidal gas composition, invasive blood pressure monitored through the right radial artery, and central venous pressure monitoring. During the performance of coronary anastomosis, full systemic heparinization with 240 mg of unfractionated heparin (300 U/kg) was used. Effectiveness of anticoagulation was monitored intraoperatively by the activated coagulation time (ACT), maintaining an ACT 400 seconds throughout coronary artery grafting. On completion of the anastomoses, the heparin was fully reversed using 240 mg of protamine sulfate (1:1 ratio). The left internal mammary artery was found unsuitable after harvesting, and a solitary saphenous vein graft was used from the aorta to the distal left anterior descending artery. The procedure was well tolerated without any hemodynamic compromise, and no inotropic support was required. After surgery, the patient was returned to the intensive care unit. The first 2 hours in the intensive care unit were complicated by persistent systolic hypotension of 75 mmHg, attributed to excessive bleeding from the left pleural tube. Approximately 750 mL of blood drained. This hypotension was unresponsive to transfusion of 6 U of packed red blood cells and 2,000 mL of colloid. Inotropic support (epinephrine, 0.28 g/kg/min) now was required. At this point, a sudden marked change in central venous pressure (from 7 to 20 mmHg) was noted, and transesophageal echocardiography (TEE) was performed immediately to exclude cardiac tamponade. TEE examination revealed preserved systolic function and an underfilled left ventricle. In contrast, the right ventricle was dilated and akinetic. Trivial tricuspid regurgitation was noted. The permanent pacing lead was also noted within the right ventricle. In addition to a dilated right ventricle, the main and right branches of the pulmonary artery were dilated There was no evidence of tamponade; however, a large collection of blood was seen *M.J. Platt, S. Davies, and B. Riedel

Intravascular volume monitoring and extravascular lung water in septic patients with pulmonary edema.

To evaluate whether different indicators using for guiding volume expansion are valuable tools to assess edematous lung injury in patients with septic shock. Prospective observational clinical study in a university intensive care unit. Sixteen consecutive mechanically ventilated patients developing septic shock with evidence of pulmonary edema on chest radiograph and severe hypoxemia (PaO(2)/FIO(2) <250 mmHg). A pulmonary artery catheter was used for the measurement of cardiac index (CI), central venous pressure (CVP), and pulmonary artery occlusion pressure (PAOP). A fiberoptic catheter was placed in the descending aorta. Measurements of extravascular lung water index (EVLWI), intrathoracic blood volume index (ITBVI), and total end-diastolic volume index (TEDVI) were obtained using the thermal dye dilution technique. Measurements were taken just after placement of catheters and 24 h later. Fluid balance was also estimated within the first 24 h. TEDVI and ITBVI were significantly correlated with EVLWI, but not CVP and PAOP. Analysis of 24-h changes showed that the changes in TEDVI and in ITBVI reflected the change in EVLWI, whereas PAOP, CVP, and fluid balance did not. Volume variables (TEDVI, ITBVI) are more useful indicators than pressure variables (CVP, PAOP) for assessment of EVLWI in septic patients with pulmonary edema.

Monitoring intravascular volumes for postoperative volume therapy

Background and objective: The feasibility of monitoring measured intravascular volumes and the cardiac filling pressures were compared to reflect the optimal volume status of postoperative patients. Methods: In a prospective clinical study, 14 hypovolaemic adult patients were included after cardiac surgery. All patients received 1000 mL hydroxyethyl starch after meeting the authors' criteria for hypovolaemia. Pressures were measured by use of a pulmonary artery catheter and volumes were determined by double-indicator dilution technique. Results: Stroke volume index (SVI), central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP), intrathoracic blood volume index (ITBVI) and total circulating blood volume (TBVIcirc) increased significantly after volume loading (30.7 ± 9.8 to 41.7 ± 9.6 mL m−2, 4.9 ± 1.7 to 9.1 ± 2.3 mmHg, 6.6 ± 1.3 to 10.6 ± 1.9 mmHg, 858 ± 255 to 965 ± 163 mL m−2, and 1806 ± 502 to 2110 ± 537 mLm−2, respectively). During the subsequent 1 h steady-state period, CVP and PAOP decreased significantly (9.1 ± 2.2 to 7.4 ± 2.2 mmHg and 10.6 ± 1.9 to 9.2 ± 2.0 mmHg, respectively), whereas SVI and intravascular volumes remained unchanged. The changes of CVP and PAOP did not correlate with changes in stroke volume during volume loading (r2 = 0.06 and 0.03, respectively) and during steady-state (r2 = 0.17 and 0.00 respectively). On the other hand, a significant correlation was found between changes of the intrathoracic blood volume and changes in stroke volume during the volume loading (r2 = 0.67) and also during the steady-state phase (r2 = 0.83). Conclusions: Intrathoracic blood volume reflects more accurately the preload dependency of cardiac output in postoperative patients than left/right-sided cardiac filling pressures.

Randomized controlled trial to investigate influence of the fluid challenge on duration of hospital stay and perioperative morbidity in patients with hip fractures

A prospective, randomized controlled trial comparing conventional intraoperative fluid management with two differing methods of invasive haemodynamic monitoring to optimize intraoperative fluid therapy, in patients undergoing proximal femoral fracture repair under general anaesthesia. Ninety patients randomized to three groups; conventional intraoperative fluid management (Gp CON, n=29), and two groups receiving additional repeated colloid fluid challenges guided by central venous pressure (Gp CVP, n=31) or oesophageal Doppler ultrasonography (Gp DOP, n=30). Primary outcome measures were time to medical fitness to discharge, hospital stay and postoperative morbidity. The fluid challenge resulted in significantly greater perioperative changes in central venous pressure between Gp CVP and Gp CON (mean 5 (95% confidence interval 3-7) mm Hg) (P<0.0001). Important perioperative changes were also shown in Gp DOP with increases of 49.4 ms (19.7-79.1 ms) in the corrected flow time, 13.5 ml (7.4-19.6 ml) in stroke volume, and 0.9 (0.49-1.39) litre min(-1) in cardiac output. As a result, fewer patients in Gp CVP and Gp DOP experienced severe intraoperative hypotension (Gp CON 28% (8/29), Gp CVP 9% (3/31), Gp DOP 7% (2/30), P=0.048 (chi-squared, 2 degrees of freedom (df). No differences were seen between the three groups when major morbidity and mortality were combined, P=0.24 (chi-squared, 2 df). Postoperative recovery for survivors, as defined by time to be deemed medically fit for discharge, was significantly faster, in comparison with Gp CON, in both the Gp CVP (10 vs 14 (95% confidence interval 8-12 vs 12-17) days, P=0.008 (t-test)), and Gp DOP (8 vs 14 (95% confidence interval 6-12 vs 12-17) days, P=0.023 (t-test). There were no significant differences between groups, for survivors, with respect to acute orthopaedic hospital and total hospital stay. Invasive intraoperative haemodynamic monitoring with fluid challenges during repair of femoral fracture under general anaesthetic shortens time to being medically fit for discharge.

Doppler velocimetry for predicting fetal death in a twin pregnancy

Doppler velocimetry for predicting fetal death in a twin pregnancy

Percutaneous transluminal mitral valvuloplasty improves cardiopulmonary baroreflex sensitivity in patients with mitral stenosis

Patients with heart failure frequently have increased sympathetic tone, which could result in part from impairment of the inhibitory influence of cardiopulmonary baroreflexes. Percutaneous transluminal mitral valvuloplasty (PTMV) provides a unique model for evaluating functional changes in cardiopulmonary baroreflexes without open-heart surgical manipulation. We examined the effects of PTMV on cardiopulmonary baroreflexes and sympathetic nerve activity in 10 patients with mitral stenosis. We measured muscle sympathetic nerve activity using microneurography. Cardiopulmonary baroreflex provocation was performed by applying a lower body negative pressure of −10 mm Hg, and its sensitivity was determined by dividing the percent change in muscle sympathetic nerve activity by the change in central venous pressure. Response to isometric exercise was assessed by handgrip at 30% of maximal voluntary contraction for 3 min. PTMV significantly increased mitral valve area and cardiac index and decreased mean left atrial pressure. PTMV significantly decreased burst rate from 25.1±2.5 to 15.6±2.6 bursts/min ( p<0.01) and burst incidence from 37.1±3.7 to 23.6±3.3 bursts/100 heart beats ( p<0.01). After PTMV, cardiopulmonary baroreflex sensitivities measured using burst rate and burst incidence were −39.9±4.9%/mm Hg and −38.7±6.2%/mm Hg, respectively, which were significantly steeper than those before PTMV (−9.2±1.1%/mm Hg and −8.4±1.1%/mm Hg; p<0.01). There were significant correlations between muscle sympathetic nerve activity at rest and cardiopulmonary baroreflex sensitivity. PTMV did not affect muscle sympathetic responses to handgrip exercise. These results suggest that patients with mitral stenosis have baseline sympathetic nerve activation, which could result in part from impaired cardiopulmonary baroreflexes.

Hemodynamic Monitoring by Double-Indicator Dilution Technique in Patients After Orthotopic Heart Transplantation

A transpulmonary thermal-dye dilution (TDD) technique using cold indocyanine green dye was utilized to monitor cardiac index (CI) and preload in patients after heart transplantation. Preload, determined by intrathoracic blood volume index (ITBVI) and global end-diastolic volume index (GEDVI), was compared to central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) and was correlated with stroke volume index (SVI). Prospective study. Cardiac surgery ICU at a university hospital. Forty patients (34 men, 6 women) with a mean (+/- SD) age of 54.4+/-8.5 years after orthotopic heart transplantation. CI and preload measurements were performed with TDD and pulmonary artery catheters in the ICU at 3, 6, 12, 24, 36, 48, and 72 h postoperatively. The femoral artery CI was compared with the pulmonary artery CI. Changes in the ITBVI, GEDVI, CVP, and PAOP were correlated with changes in the SVI. No difference was found between the femoral and pulmonary arterial CIs (r = 0.98 [bias, 0.35 L/min/m(2)]; p<0.01). There was no statistically significant correlation between changes in the SVI and changes in CVP (r = -0.23,) and PAOP (r = -0.06). However, the ITBVI (r = 0.65; p<0.01) and the GEDVI (r = 0.73; p<0.01) were significantly correlated to changes in the SVI. Changes in the same direction occurred between the SVI and the GEDVI as well as between the SVI and the ITBVI in 76.3% and 71.9% of patients, respectively, while CVP and PAOP also changed in the same direction as SVI in only 35.1% and 36.9% of patients, respectively. ITBVI and GEDVI are more reliable preload parameters than CVP and PAOP. Even in denervated hearts, ITBVI and GEDVI show significant correlations with SVI. The transpulmonary indicator dilution technique is promising and should be investigated further.

Changes in Central Venous Pressure and Pulmonary Capillary Wedge Pressure Do Not Indicate Changes in Right and Left Heart Volume in Patients Undergoing Coronary Artery Bypass Surgery

The value of pulmonary artery catheterization is a matter for discussion. Previous studies suggest that direct measurements of intravascular volume distribution and cardiac volume indices may be of greater relevance than central venous and pulmonary capillary wedge pressure. We therefore used a thermo-dye dilution technique for the quantification of central blood volume, right ventricular end-diastolic volume and left heart volume in patients undergoing coronary artery bypass surgery. Measurements were performed after the induction of anaesthesia as well as 1, 6 and 24 h after surgery. Central venous pressure was significantly increased at 1 and 6 h, whereas right ventricular end-diastolic volume was increased only at 6 h post-operatively. Pulmonary capillary wedge pressure showed a tendency to increase whereas left heart and central blood volume decreased significantly after surgery. The results of the present study suggest that changes in cardiac filling pressure do not indicate changes in indices of cardiac volume in patients after coronary bypass surgery.

Role of endothelin receptor subtypes in volume-stimulated ANF secretion.

The role of endothelin (ET) receptors was tested in volume-stimulated atrial natriuretic factor (ANF) secretion in conscious rats. Mean ANF responses to slow infusions (3 x 3.3 ml/8 min) were dose dependently reduced (P < 0.05) by bosentan (nonselective ET-receptor antagonist) from 64.1 +/- 18.1 (SE) pg/ml (control) to 52.6 +/- 16.1 (0.033 mg bosentan/rat), 16.1 +/- 7.6 (0. 33 mg/rat), and 11.6 +/- 6.5 pg/ml (3.3 mg/rat). The ET-A-receptor antagonist BQ-123 (1 mg/rat) had no effect relative to DMSO controls, whereas the putative ET-B antagonist IRL-1038 (0.1 mg/rat) abolished the response. In a second protocol, BQ-123 (>/=0.5 mg/rat) nonsignificantly reduced the peak ANF response (106.1 +/- 23.0 pg/ml) to 74.0 +/- 20.5 pg/ml for slow infusions (3.5 ml/8.5 min) but reduced the peak response (425.3 +/- 58.1 pg/ml) for fast infusions (6.6 ml/1 min) by 49.9% (P < 0.001) and for 340 pmoles ET-1 (328.8 +/- 69.5 pg/ml) by 83.5% (P < 0.0001). BQ-123 abolished the ET-1-induced increase in arterial pressure (21.8 +/- 5.2 mmHg at 1 min). Changes in central venous pressure were similar for DMSO and BQ-123 (slow: 0.91 and 1.14 mmHg; fast: 4.50 and 4.13 mmHg). The results suggest 1) ET-B receptors mainly mediate the ANF secretion to slow volume expansions of <1.6%/min; and 2) ET-A receptors mainly mediate the ANF response to acute volume overloads.

Acute hemodynamic effects of post cardiotomy peritoneal dialysis in neonates and infants.

Evaluation of the acute hemodynamic changes during peritoneal dialysis in patients with low cardiac output syndrome and acute renal failure after open heart surgery. Three newborns and three infants after corrective surgery of congenital heart disease with post cardiotomy dialysis. Five of these had an open thorax during dialysis. Cardiac output measurements using the thermodilution technique on two consecutive days at four different times during the peritoneal dialysis cycle. We did not find a deterioration of the cardiac index or systemic vascular resistance measured over two cycles in each of the six patients. Pulmonary artery pressure rose slightly after instillation of the dialysate solution in all patients. Changes in central venous pressure and left atrial pressure were not clinically meaningful. In all patients fluid removal by peritoneal dialysis was effective. All five surviving patients recovered renal function. Peritoneal dialysis can be performed in newborns and infants following cardiac surgery without causing acute hemodynamic imbalances. An open chest may have a significant impact on hemodynamic stability during peritoneal dialysis by blunting any possible negative alterations of increased intraabdominal pressure.

Evaluation of the Effect of Pleural Effusion on Central Venous Pressure in Cats

This study was undertaken to determine if pleural effusion (PEF) increases central venous pressure (CVP) in cats, to define any relationship between volume of PEF and CVP, and to ascertain the significance of CVP alterations in cats having PEF and suspected right heart failure (RHF). CVP was measured from a jugular vein before (CVPpre) and after (CVPpost) bilateral thoracentesis in 9 cats with naturally occurring PEF and under experimental conditions in 3 spontaneously breathing anesthetized cats receiving graded intrathoracic infusion of saline. Volumes of introduced and recovered fluid were recorded. A significant decrease occurred in CVP after thoracentesis in cats with naturally occurring PEF (mean difference, 4.5 cm H2O; range, 0–7.0 cm H2O, P &gt; .005). The magnitude of change in CVP was constant (r = 0.36, P &gt; .05) over the range of volumes recovered (range, 95–450 mL or 16.4–90 mL/kg). Five cats had CVPpre suggestive of RHF (range, 8.16–20.4 cm H2O). After thoracentesis, RHF was ruled out in 1 cat (CVPpost, 4.08 cm H2O) and the CVP declined but remained abnormally high (9.52 cm H2O) in 1 cat with a mediastinal mass. In 2 cats with confirmed RHF (CVPpre, 20.4 and 16.3 cm H2O), CVP decreased after thoracentesis but remained abnormally high (CVPpost, 14.96 and 10.88 cm H2O). In 1 cat with noncardiogenic PEF and inadequate removal of fluid, CVPpost (8.16 cm H2O) did not decrease. Experimentally, a positive linear relationship was observed between CVP and volume of PEF. The threshold volume required to increase CVP (17 mL/kg) approximated that suggested by clinical observation (22 mL/kg). PEF increases CVP and can cause abnormally high CVP in the absence of RHF.

Comparison between intrathoracic blood volume and cardiac filling pressures in the early phase of hemodynamic instability of patients with sepsis or septic shock

Purpose: The purpose of this study was to analyze three different variables of cardiac preload; central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP), and intrathoracic blood volume index (ITBVI) that served as the best indicator of cardiac function, that is, cardiac index (C0 or stroke index (SI). Materials and Methods: This was a prospective study in 57 critically ill patients with sepsis or septic shock in whom 581 hemodynamic profiles were analyzed. One patient was included a second time after a period of 6 weeks. All patients were sedated and mechanically ventilated. Each patient had a 7.5-Fr five-lumen pulmonary artery catheter (PAC) and a 4-Fr catheter with an integrated thermistor and fiberoptic that was advanced into the descending aorta via a femoral artery sheath. The study was performed in the surgical intensive care unit of a university hospital. Results: Linear regression analysis of the first profile for each case (n = 58) revealed a significant correlation between ITBVI and SI (r = 0.66). For comparison, correlations for PAOP/SI (r = 0.06) and CVP/SI (r = 0.10) were poor. The analysis of all second profiles showed that only the change in ITBVI reflected the change in SI (r = 0.67), whereas PAOP (r = 0.07) and CVP (r = 0.05) failed. Furthermore, a positive change in SI (n = 265) was most often associated with an increase in ITBVI (n = 189, 71.3%), less for PAOP (n = 122, 46.0%) and CVP (n = 137, 51.7%). A reduction in SI (n = 256) was accompanied by a decrease in ITBVI (n = 176, 68.8%), PAOP (n = 119,46.5%), and CVP (n = 118,46.1%). An increase in ITBVI (n = 269) was accompanied by an increase in SI in 189 cases (70.3%). In these, PAOP increased only in 91 (48.1%) and CVP in 101 cases (53.4%), respectively. Accordingly, a positive change in PAOP (n = 218) was associated with an increase in SI in 122 cases (56.0%). ITBVI increased in 91 (74.6%) and CVP in 84 (68.9%) of these cases. A decrease in ITBVI (n = 250) was associated with a decrease in SI in 176 cases (70.4%). Decreases in PAOP (n = 89, 50.6%) and CVP (n = 91, 51.7%) did not reflect these changes. However, when PAOP (n = 229) and SI decreased (n = 119,52.0%), ITBVI decreased in 89 (74.8%) and CVP in 73 cases (61.3%). Conclusions: In comparison with cardiac filling pressures, ITBVI seems to be the more reliable indicator of cardiac preload in patients with sepsis or septic shock.

Changes in central venous pressure and pulmonary capillary wedge pressure do not indicate changes in right and left heart volume in patients undergoing coronary artery bypass surgery.

The value of pulmonary artery catheterization is a matter for discussion. Previous studies suggest that direct measurements of intravascular volume distribution and cardiac volume indices may be of greater relevance than central venous and pulmonary capillary wedge pressure. We therefore used a thermo-dye dilution technique for the quantification of central blood volume, right ventricular end-diastolic volume and left heart volume in patients undergoing coronary artery bypass surgery. Measurements were performed after the induction of anaesthesia as well as 1, 6 and 24 h after surgery. Central venous pressure was significantly increased at 1 and 6 h, whereas right ventricular end-diastolic volume was increased only at 6 h post-operatively. Pulmonary capillary wedge pressure showed a tendency to increase whereas left heart and central blood volume decreased significantly after surgery. The results of the present study suggest that changes in cardiac filling pressure do not indicate changes in indices of cardiac volume in patients after coronary bypass surgery.

Changes in central venous pressure and pulmonary capillary wedge pressure do not indicate changes in right and left heart volume in patients undergoing coronary artery bypass surgery

Changes in central venous pressure and pulmonary capillary wedge pressure do not indicate changes in right and left heart volume in patients undergoing coronary artery bypass surgery

Evaluation of the effect of pleural effusion on central venous pressure in cats.

This study was undertaken to determine if pleural effusion (PEF) increases central venous pressure (CVP) in cats, to define any relationship between volume of PEF and CVP and to ascertain the significance of CVP alterations in cats having PEF and suspected right heart failure (RHF). CVP was measured from a jugular vein before (CVPpre) and after (CVPpost) bilateral thoracentesis in 9 cats with naturally occurring PEF and under experimental conditions in 3 spontaneously breathing anesthetized cats receiving graded intrathoracic infusion of saline. Volumes of introduced and recovered fluid were recorded. A significant decrease occurred in CVP after thoracentesis in cats with naturally occurring PEF (mean difference, 4.5 cm H2O; range, 0-7.0 cm H2O, P < .005). The magnitude of change in CVP was constant (r = 0.36, P > .05) over the range of volumes recovered (range, 95-450 mL or 16.4-90 mL/kg). Five cats had CVPpre suggestive of RHF (range, 8.16-20.4 cm H2O). After thoracentesis, RHF was ruled out in 1 cat (CVPpost, 4.08 cm H2O) and the CVP declined but remained abnormally high (9.52 cm H2O) in 1 cat with a mediastinal mass. In 2 cats with confirmed RHF (CVPpre, 20.4 and 16.3 cm H2O), CVP decreased after thoracentesis but remained abnormally high (CVPpost, 14.96 and 10.88 cm H2O). In 1 cat with noncardiogenic PEF and inadequate removal of fluid, CVPpost (8.16 cm H2O) did not decrease. Experimentally, a positive linear relationship was observed between CVP and volume of PEF. The threshold volume required to increase CVP (17 mL/kg) approximated that suggested by clinical observation (22 mL/kg). PEF increases CVP and can cause abnormally high CVP in the absence of RHF.

Assessment of cardiovascular volume status by transoesophageal echocardiography and dye dilution during cardiac surgery.

Conventional evaluation of cardiovascular volume status by filling pressures is unreliable in critically ill patients. Measurements of left ventricular end diastolic area index by transoesophageal echocardiography and of intrathoracic blood volume index by dye indicator dilution are new approaches to this problem. In this study, different indices of cardiovascular volume status were analysed to define their relation during the pronounced haemodynamic changes associated with systemic inflammation after cardiopulmonary bypass. Correlations were performed with left ventricular end diastolic area index, intrathoracic blood volume index, central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP). Data from 15 patients receiving coronary artery bypass grafts were compared after induction of anaesthesia and in the intensive care unit. Spearman's correlation coefficient for perioperative absolute changes in left ventricular end diastolic area index and intrathoracic blood volume index was 0.87 (P < 0.05). However, an increase in intrathoracic blood volume index by 125 mL m-2 was necessary to maintain a baseline left ventricular end diastolic area index. Absolute values of all variables varied widely, with the only significant correlation found between CVP and PCWP. Changes in CVP and PCWP did not correlate with changes in left ventricular end diastolic area index or intrathoracic blood volume index. Provided simultaneous baseline measurements are available and a supranormal intrathoracic blood volume index compensates for the haemodynamic changes in systemic inflammation, left ventricular end diastolic area index and intrathoracic blood volume index may substitute for each other during the evaluation of cardiovascular volume status in patients with stable cardiac function.

Short-term outcome and predictors of adverse events following pulmonary thromboendarterectomy.

Pulmonary complications including hypoxemia, right heart failure, and prolonged ventilation may follow pulmonary thromboendarterectomy (PTE) performed via cardiopulmonary bypass (CPB) with deep hypothermic circulatory arrest. Seventeen adult patients have undergone PTE at the University of Maryland Medical System during the preceding 3 years. From these patients, clinical and hemodynamic parameters were tabulated pre-CPB, post-CPB, at admission to the intensive care unit (ICU), and prior to discontinuation of invasive monitoring in the ICU. Data on anthropometric variables, survival, and times of extracorporeal circulation, mechanical ventilation, and hospital stay were also collected. The mean values for pulmonary arterial systolic and diastolic pressures and pulmonary vascular resistance (PVR) decreased significantly from pre-CPB values after PTE (all p < 0.05). Mild mixed acidosis present at ICU admission resolved prior to discharge (p = 0.002). The length of mechanical ventilation time was positively correlated with the absolute post-CPB PVR and negatively correlated with the relative change in central venous pressure (CVP) from pre-CPB to post-CPB values (r = 0.75, p = 0.037). Of the pre-CPB anthropometric variables, only body mass index was significantly higher in nonsurvivors (p = 0.037). Pulmonary artery pressures and vascular resistance fall significantly after PTE. A lower post-CPB PVR and a relatively decreased (i.e., from pre-CPB values) CVP predict reduced length of postoperative ventilation but not of the hospital stay. Mortality appears increased in patients with a large body habitus.

Is tension pneumothorax a threat in trauma laparoscopy?

Tension pneumothorax is a reported risk with pneumoperitoneum in the presence of diaphragmatic injuries. A goat model with and without diaphragmatic injury was used to determine if varying levels of intra-abdominal pressure (IAP) result in tension pneumothorax. Twenty-four goats were divided equally into four groups: (1) 5 mm Hg IAP control, (2) 15 mm Hg IAP control, (3) 5 mm Hg IAP with diaphragmatic injury, (4) 15 mm Hg IAP with diaphragmatic injury. Chest x-ray films were made and heart rate (HR), mean arterial pressure, central venous pressure (CVP), arterial blood gases, and airway pressure (AP) were measured at 10-minute intervals up to 30 minutes. Significant changes were determined by using the one-way analysis of variance and Mann-Whitney test with alpha set at p < 0.05. In group 4, 100% (all six goats) developed radiographic evidence of tension pneumothorax by 10 minutes. Mean changes from baseline at 20 minutes for the following parameters were all significantly different from controls: HR (p < 0.05), CVP (p < 0.0001), PaO2 (p < 0.001), and AP (p < 0.004). Mortality was 67% (four of six) at 25 minutes. In group 3, 100% (all six goats) of the animals developed radiographic evidence of a simple pneumothorax without mediastinal shift. In this group, there were significant changes in PaO2 (p < 0.003), AP (p < 0.04), and HR (p < 0.05). Mortality was 16% (one of six) at 25 minutes. In this goat model of diaphragmatic injury, tension pneumothorax is a significant threat when pneumoperitoneum is maintained at 15 mm Hg IAP. Pneumoperitoneum at 5 mm Hg IAP leads to simple pneumothorax with deleterious effects on oxygenation. Changes in AP, CVP, HR, and PaO2 provide early clues to the development of the problem.

Experience with kidney transplantation in children and adolescents.

Paediatric kidney transplantation has different aspects in adults in terms of underlying primary renal disease, surgical technique, perioperative care and graft prognosis. Significant urological problems are present in a high percentage of paediatric recipients. This study was undertaken to characterize paediatric kidney transplantation as performed at our institutes. Twenty-eight patients (age range 4-17 years, 10 girls, 18 boys) were included in this study. We analyzed (1) urologic procedures performed prior to or simultaneously with transplantation, (2) intraoperative changes in haemodynamics, (3) postoperative complications and (4) acute allograft rejection and graft prognosis. Of 4 patients with lower urinary tract abnormalities (neurogenic bladder in 3, posterior urethral valve in 1), 2 underwent augmentation ileocystoplasty prior to transplantation. The Mitrofanoff procedure as a diversion for neourethra was also performed in 2 of the 4 patients. All these 4 patients were managed with clean intermittent catheterization. Central venous pressure changes before and after graft vessel declamping were much greater in patients with body weight below 25 kg than in those above 25 kg. Five surgical complications and 6 infections were encountered postoperatively and hypertension was lasting in 6. Thirteen patients experienced 19 periods of acute allograft rejection. All of the 24 patients in the cyclosporin era (1986-) overcame rejections and they are all alive with good graft function. As long as proper pretransplant patient evaluation and management, and intensive perioperative care are undertaken, good prognosis of renal allograft can be achieved in young patients.

Muscle metaboreflex increases ventricular performance in conscious dogs.

Ischemia of active skeletal muscle stimulates neuronal afferents within the muscle, which elicits a reflex increase in systemic arterial pressure (SAP), heart rate (HR), and cardiac output (CO) termed the muscle metaboreflex. We investigated whether activation of the muscle metaboreflex elicits increases in ventricular performance using conscious, chronically instrumented dogs trained to run on a treadmill (3.2 km/h, 0% grade). The muscle metaboreflex was activated via progressive partial vascular occlusion of the terminal aorta during control experiments and with HR maintained constant via a pacemaker connected to ventricular electrodes (225 beats/min). In control experiments, hindlimb ischemia elicited substantial increases in SAP, HR, and CO (+53.9 +/- 4.3 mmHg, +32.4 +/- 4.5 beats/min, and +1.57 +/- 0.22 l/min, respectively; all changes P < 0.05), whereas stroke volume (SV) remained unchanged with reflex activation (control 45.9 +/- 2.3 vs. 46.1 +/- 2.4 ml, P > 0.05). During metaboreflex activation at constant HR, SV significantly increased such that the increases in CO and SAP were not significantly different from control experiments (+1.77 +/- 0.56 l/min and +57.4 +/- 3.8 mmHg, P > 0.05 vs. control experiments). No significant change in central venous pressure occurred in either experiment, indicating no Frank-Starling effect on SV. We conclude that muscle metaboreflex-induced increases in ventricular contractility act to sustain SV despite decreases in ventricular filling time due to the tachycardia such that the sustained SV coupled with the tachycardia elicits substantial increases in CO that contribute importantly to the reflex increase in SAP.