The Precision of Pulmonary Artery Catheter Bolus Thermodilution Cardiac Output Measurements Varies With the Clinical Situation.

OBJECTIVE: To investigate the effects of ventilatory mode, injectate temperature, and clinical situation on the precision of cardiac output measurements. DESIGN: Randomized, prospective observational study. SETTING: Single university hospital. PARTICIPANTS: Forty patients undergoing planned cardiac surgery, receiving a pulmonary artery catheter according to institutional routine. INTERVENTIONS: Cardiac output was measured at 4 predefined time points during the perioperative patient course, twice during controlled and twice during spontaneous ventilation, using 2 blocks of 8 measurement replications with cold and tepid injectate in random order. MEASUREMENTS AND MAIN RESULTS: The data were analyzed using a hierarchical linear mixed model. Clinical precision was determined as half the width of the 95% confidence interval for the underlying true value. The single-measurement precision measured in 2 different clinical situations for each temperature/ventilation combination was 8% to 10%, 11% to 13%, 13% to 15%, and 23% to 24% in controlled ventilation with cold injectate, controlled ventilation with tepid injectate, spontaneous breathing with cold injectate, and spontaneous breathing with tepid injectate, respectively. Tables are provided for the number of replications needed to achieve a certain precision and for how to identify significant changes in cardiac output. CONCLUSIONS: Clinical precision of cardiac output measurements is reduced significantly during spontaneous relative to controlled ventilation. The differences in precision between repeated measurement series within the temperature/ventilation combinations indicate influence of other situation-specific factors not related to ventilatory mode. Compared with tepid injectate in patients breathing spontaneously, the precision is 3-fold better with cold injectate and controlled ventilation.

Transcutaneous aortic valve implantation: recent advances and future.

PURPOSE OF REVIEW: To present recent experiences and studies on transcutaneous aortic valves implantation for severe aortic stenosis in elderly patients with high-risk profile. RECENT FINDINGS: The surgical implantation of aortic valves is a highly efficient and safe procedure but some patients with a high-risk profile are denied surgery. Transcutaneous implantation of aortic valves has evolved as an alternative. Two major systems are available, the Edwards SAPIEN and the Medtronic CoreValve. Selection of patients is based on high age and elevated risk. The risk prediction of the scoring systems should be scrutinized. The anesthesiological approach has partly been determined by the procedural route. General anesthesia is used for transapical approach and transarterial procedures. Local anesthesia and awake or sedated patient can be used for transarterial approach. General anesthesia facilitates the use of perioperative transesophageal echocardiography. SUMMARY: Selection of patients is at present done by criteria such as age above 70-75 years and logistic European system for cardiac operative risk evaluation predicting a risk of death above 20%. The logistic European system for cardiac operative risk evaluation tends to overestimate risk, a fact that should be taken into consideration in patient selection. Trends indicate that the procedure may take a larger part of open surgery for aortic stenosis in the elderly. The consequences for the future of cardiac surgery remain to be seen.

[A young woman with cardiac arrest]. / Ung kvinne med hjertestans.

A 20-year-old woman presented with dyspnoea in the Emergency department and subsequently suffered a cardiac arrest. The initial rhythm was PEA (pulseless electrical activity). She had intermittent return of spontaneous circulation. Transthoracic echocardiography showed a dilated hypokinetic right ventricle and a collapsed left ventricle. The tentative diagnosis was pulmonary embolism, but she remained hemodynamically unstable despite thrombolysis. 90 min after the collapse she was put on cardiopulmonary bypass and surgical embolectomy was performed. Large masses of thrombotic material were collected from central parts of the right and left pulmonary artery. Therapeutic hypothermia was applied for 24 hours postoperatively. The remaining hospital stay was uneventful and ten days after the presentation she was transferred to her local hospital. At this point she was without neurological sequelae. The patient had used oral contraceptives (ethinyl estradiol/ drospirenone).

The marked reduction in mixed venous oxygen saturation during early mobilization after cardiac surgery: the effect of posture or exercise?

Early mobilization after cardiac surgery induces a marked reduction in mixed venous oxygen saturation (Svo2). Using pulmonary artery catheters and indirect calorimetry, we investigated the effects of exercise and postural change on cardiac index (CI) and Svo2 before and on the first morning after coronary artery bypass surgery. Sixteen patients with an ejection fraction >0.50 were studied at rest, during supine bicycle exercise, and during passive standing. Supine cycling at 30 W increased CI by 1.5 +/- 0.8 L x min(-1) x m(-2) before and 0.9 +/- 0.7 L x min(-1) x m(-2) after surgery (P < 0.05), whereas Svo2 was reduced from 80% +/- 4% at rest to 63 +/- 6% preoperatively (P < 0.05) and from 71% +/- 5% to 46% +/- 11% postoperatively (P < 0.05). Passive standing reduced CI by 0.8 +/- 0.5 L x min(-1) x m(-2) before and 0.3 +/- 0.4 L x min(-1) x m(-2) after surgery (P < 0.05). Svo2 was reduced from 79% +/- 5% to 64% +/- 7% preoperatively (P < 0.05) and from 72% +/- 6% to 60% +/- 6% postoperatively (P < 0.05). The exercise challenge revealed an altered cardiovascular response after surgery, causing a larger reduction in Svo2 for the same workload. Passive standing significantly reduced Svo2 both days, but this effect was less pronounced after surgery. The response to postural change and exercise was altered after surgery and may both contribute to the reduction in Svo2 during postoperative mobilization.

Inflammatory response after open heart surgery: release of heat-shock protein 70 and signaling through toll-like receptor-4.

BACKGROUND: Coronary artery bypass grafting with the use of cardiopulmonary bypass is known to mediate an inflammatory response. The stress-inducible heat-shock protein (HSP) 70 has been detected in myocardial cells after CABG, and toll-like receptors (TLRs) are suggested as putative signaling receptors for the HSPs, mediating synthesis of inflammatory cytokines. The main aims of our study were to explore the release of HSP70 and the regulation of monocyte TLR-2 and TLR-4 expression after CABG. METHODS AND RESULTS: Twenty patients referred for elective CABG were included in this study. Using immunoassays, we detected HSP70 in plasma after CABG, with peak concentration immediately after surgery. Interleukin-6 in plasma reached peak concentration 5 hours after surgery. Monocyte CD14, TLR-2, and TLR-4 expression, as analyzed by flow cytometry, was initially downregulated. On day 1, CD14 expression normalized, whereas TLR-2 and TLR-4 expression was upregulated. TLR-4 was significantly upregulated even on postoperative day 2. Additional experiments revealed that peritoneal macrophages from control (C3H/HeN) mice responded to HSP70 with release of tumor necrosis factor, whereas macrophages from mutated TLR-4 (C3H/HeJ) mice were unresponsive. In vitro, human adherent monocytes responded to recombinant HSP70 with interleukin-6 and tumor necrosis factor release. CD14 and TLR-4 monoclonal antibodies inhibited the cytokine response. CONCLUSIONS: In this study, we observed an immediate release of HSP70 into the circulation and a modulation of monocyte TLR-2 and TLR-4 expression after CABG. TLR-4 and CD14 appear to be involved in an HSP70-mediated activation of innate immunity.

Markers for endothelial activation during open heart surgery.

BACKGROUND: Reliable markers for endothelial activation are needed when studying biocompatibility of cardiopulmonary bypass. METHODS: Blood samples from 21 patients undergoing combined valve and coronary artery bypass surgery were collected before anesthesia (T1), after re-transfusion of blood from the heart-lung machine (T2), and on the first postoperative morning (T3). Concentrations of soluble markers were determined using sandwich enzyme-linked immunoadsorbent assay for sICAM-1, sVCAM-1, and sE-selectin. The sera were also used to stimulate human umbilical vein endothelial cells (HUVEC) in culture for 6 hours, in which activation was measured using cell enzyme immunoassay for mICAM-1 and mVCAM-1. RESULTS: The concentrations of sICAM-1 and sVCAM-1 increased during both measurement intervals (p < 0.05). The sICAM-1 T1 was 311.0 ng/mL (range, 271.0 to 350.7 ng/mL); the sICAM-1 T2 was 341.6 ng/mL (range, 322.0 to 422.0 ng/mL), and the sICAM-1 T3 was 400.2 ng/mL (range, 348.0 to 556.4 ng/mL; the sVCAM-1 T1 was 607.5 ng/mL (range, 497.8 to 813.8 ng/mL), the sVCAM-1 T2 was 755.3 ng/mL (range, 660.6 to 834.4 ng/mL), and the sVCAM-1 T3 was 1149.0 ng/mL (946.0 to 1406.0 ng/mL); whereas the sE-selectin increased from T1 to T3 (p < 0.01). Both the mICAM-1 (p < 0.002) and the mVCAM-1 (p < 0.005) increased on the human umbilical vein endothelial cells in culture after stimulation with the patient sera. The amounts of soluble markers in vivo were not correlated with the degree of endothelial activation in vitro, but were correlated with various operative variables including age, medication, and time of aortic cross-clamping. CONCLUSIONS: Endothelial cells were activated during cardiopulmonary bypass. The soluble adhesion molecules sICAM-1, sVCAM-1, and sE-selectin displayed different kinetics, rendering it difficult to determine a simple expression for the degree of endothelial cell activation. Clinically, sVCAM-1 seemed to be the best-suited marker for endothelial cell activation, because it was only associated with aortic cross-clamping and heparin and protamine doses, and it also showed the largest numerical changes.

Marked mixed venous desaturation during early mobilization after aortic valve surgery.

UNLABELLED: We investigated the physiological reaction to mobilization the first and second day after aortic valve replacement in an open, prospective study. Hemodynamic and oxygenation variables were recorded in 15 patients using a pulmonary artery oximetry catheter and bench oximetry. Serious intraoperative events occurred in 3 patients, but all patients began mobilization on the first postoperative day and mobilization was accomplished without clinical problems. Mixed venous oxygen saturation (SvO(2)) at rest was 58.0 +/- 7.7% (mean +/- SD) on the first postoperative day and 58.0 +/- 6.2% on the second day (NS). During mobilization, oxygen consumption increased by 64 +/- 41% and 58 +/- 33% on the first and second days (P < 0.01; NS between days). No compensatory increase in cardiac index and oxygen delivery was seen. Oxygen extraction increased, resulting in SvO(2) values during exercise of 35.7 +/- 6.8% on the first day and 36.7 +/- 7.7% on the second day (P < 0.01; NS between days), whereas mixed venous oxygen partial pressure was 3.0 +/- 0.4 kPa on both days. The lowest recorded value for SvO(2) was 10%. The marked and consistent mixed venous desaturation during early mobilization has not been described before and the clinical consequences and underlying mechanism require further investigation. IMPLICATIONS: During early mobilization after aortic valve replacement, a marked and consistent reduction in mixed venous oxygen saturation to 35% and mixed venous oxygen partial pressure to 3 kPa was observed.

Guiding surgical cannulation of the inferior vena cava with transesophageal echocardiography.

UNLABELLED: We studied 150 adult cardiac surgery patients to assess visualization of the venous cannula and the venous system by intraoperative transesophageal echocardiography and to register the incidence of cannulation of hepatic veins. The quality of images, the dimensions of the venous system, the position of the venous cannula, and the adequacy of venous return were registered. Acceptable image quality of the inferior vena cava and the right hepatic vein (RHV) was obtained in 95% and 87% of cases, respectively. Considerable individual variations were found in the dimensions of the venous system. The cannula position could be determined in 99% of the cases. Ten percent of venous cannulae were primarily placed in the RHV. A short distance between the eustachian valve and the RHV possibly predisposes to cannulation of the RHV. No other patient-related factors were associated with cannula position. Placement of the cannula deep in the inferior vena cava was associated with reduced venous return and may be a more important cause of reduced return than a cannula positioned in a hepatic vein. IMPLICATIONS: Correct positioning of the venous cannula draining blood to the cardiopulmonary bypass circuit is important. Intraoperative transesophageal echocardiography allows satisfactory determination of the cannula position in nearly all patients. Ten percent of venous cannulae are primarily positioned in the right hepatic vein and not in the inferior vena cava as intended.