Relocation of patients after cardiac surgery: is it worth the effort?

BACKGROUND: Fast-track protocols may facilitate early patient discharge from the site of surgery through the implementation of more expedient pathways. However, costs may merely be shifted towards other parts of the health care system. We aimed to investigate the consequence of patient transfers on overall hospitalisation, follow-up and readmission rate after cardiac surgery. METHODS: A single-centre descriptive cohort study using prospectively entered registry data. The study included 4,515 patients who underwent cardiac surgery at Aarhus University Hospital during the period 1 April 2006 to 31 December 2012. Patients were grouped and analysed based on type of discharge: Directly from site of surgery or after transfer to a regional hospital. The cohort was obtained from the Western Denmark Heart Registry and matched to the Danish National Hospital Register. RESULTS: Median overall length of stay was 9 days (7.0;14.4). Transferred patients had longer length of stay, median difference of 2.0 days, p < 0.001. Time to first outpatient consultation was 41(30;58) days in transferred patients vs. 45(29;74) days, p < 0.001. 18.6% was readmitted within 30 days. Mean time to readmission was 18.4 ± 6.4 days. Median length of readmission was 3(1,6) days. There was no difference in readmissions between groups. Leading cause of readmission was cardiovascular disease with 48%. CONCLUSION: Transfer of patients does not overtly reduce health care costs, but overall LOS and time to first outpatient consultation are substantially longer in patients transferred to secondary hospitals than in patients discharged directly. Readmission rate is high during the month after surgery, but with no difference between groups.

Effects of levosimendan in patients with left ventricular hypertrophy undergoing aortic valve replacement.

BACKGROUND: Left ventricular hypertrophy is associated with adverse outcomes, including death, during cardiac surgery. This may be facilitated by an increased oxygen demand and diastolic dysfunction. Levosimendan augments haemodynamics without further oxygen consumption and improves echocardiographic indices of diastolic dysfunction. This study aimed to describe the haemodynamic effects of short-term pre- and intra-operative levosimendan infusion including advanced echocardiographic measures of diastolic and systolic heart function. METHODS: The study was randomised, double-blinded and placebo-controlled performed at a single-centre university hospital. Patients with left ventricular hypertrophy and ejection fraction > 45% scheduled for single procedure aortic valve replacement were included and randomised to infusion of either levosimendan 0.1 µg/kg/min or placebo from 4 h before anaesthesia to the end of surgery. Outcome measures were echocardiographic indices of left ventricular diastolic function: E/e' (primary endpoint), e', e'/a' and indices of systolic function: longitudinal strain, ejection fraction and s'. Patients were followed until 6 months after surgery. In addition, invasive haemodynamic measures were obtained perioperatively. RESULTS: The trial was prematurely terminated due to an overall high incidence of post-operative atrial fibrillation (15/20, P = 0.002) after inclusion of 20 patients. The relative decrease in perioperative cardiac index was lower (P = 0.016) in the levosimendan group. There was no difference in E/e', and similar results were found for all measures of systolic function. CONCLUSION: Short-term levosimendan caused a transient relative increase in cardiac index, but no effect was seen on the first post-operative day and up to 6 months post-operatively with indices of systolic and diastolic heart function.

High thoracic epidural analgesia decreases stress hyperglycemia and insulin need in cardiac surgery patients.

OBJECTIVE: Assuming that high thoracic epidural analgesia (HTEA) with the sympathetic block might decrease postoperative blood glucose (BG) level and reduce the need of insulin, the aim was to evaluate the effect of HTEA on the BG level and insulin requirement in patients undergoing cardiac surgery. MATERIALS AND METHODS: Forty-two low-risk patients age 65-79 years scheduled for elective coronary artery bypass grafting with or without aortic valve replacement were randomised to receive HTEA as supplement for general anaesthesia. BG and lactate were measured before and after cardiopulmonary bypass and postoperatively at least every 3 h together with administration of insulin. Postoperative pain was evaluated 30 min, 2, 4 and 6 h after extubation, and before discharge from the intensive care unit. RESULTS: Overall BG levels showed great variation over time (P < 0.001). No statistically significant difference was found in perioperative BG, but postoperative lower BG levels were found in HTEA patients (P = 0.042). The number of patients not receiving insulin in postoperative period was significantly higher in HTEA group (9 vs. 2, P = 0.032). No differences were seen in lactate levels. Patients in the HTEA group had significant lower pain scores (P < 0.001). CONCLUSION: HTEA preserves glucose metabolism better and leads to a lesser degree of 'stress hyperglycaemia' in cardiac surgery patients.

Agreement between cardiac outputs by four-dimensional echocardiography and thermodilution method is poor.

OBJECTIVE: The objective of the study was to determine the agreement of cardiac output (CO) measured by four-dimensional echocardiography (4D echo) to simultaneously obtain CO from pulmonary artery catheter (PAC) using thermodilution technique. MATERIALS AND METHODS: Sixty-three comparable readings from 27 patients scheduled for elective coronary artery bypass were included. All echocardiographic measurements were obtained by one experienced echocardiographer. All echo images were analyzed independently and blinded from PAC-obtained measurements. Analysis was primarily done by Bland and Altman plot. The collected data were further controlled for interobserver bias and image quality. RESULTS: Differences in CO measurements increased with higher CO, hence values were logarithmically transformed. On the logaritmic scale, the 4D echo underestimated CO by 0.37 l/min compared with PAC, indicating that PAC measurements were 1.45 times higher than the 4D echo (95% confidence interval 1.32-1.52) and limits of agreement 0.97-2.14). The interobserver bias of 4D echo measurement analysis was 0.29 l/min (95% confidence interval 0.16-0.42) and limits of agreement -0.8-1.38). No difference was seen in image quality between comparisons with good agreement compared with comparisons with poor agreement. CONCLUSION: The agreement between COs by 4D echo and standard PAC thermodilution technique was poor. 4D echo underestimates CO as compared with PAC. This is most likely caused by the analysis software or low frame rate inherent to the technique.

Sufentanil preserves hemodynamics and left ventricular function in patients with ischemic heart disease.

OBJECTIVE: Sufentanil has been reported to provide stable hemodynamics similar to other opioids. However, it has not been reliably established whether this stability can be attributed only to Sufentanil and translates into fully preserved left ventricular (LV) function. The purpose of this study was to evaluate the effect of Sufentanil on hemodynamics and LV systolic and diastolic function using invasive monitoring and echocardiography in patients with ischemic heart disease. METHODS: Prospective observational study of thirty patients acting as their own control undergoing echocardiographic imaging before and after bolus Sufentanil 1.5-2.0 µg/kg. Full invasive hemodynamic monitoring was established before Sufentanil administration. Global LV systolic function was evaluated with a global longitudinal peak systolic strain (GLPSS) by speckle tracking ultrasound; systolic displacement by tissue tracking (TT) and diastolic function was evaluated using Doppler tissue imaging and pulse wave Doppler. RESULTS: Hemodynamic monitoring showed a minor decline in systolic blood pressure from 159 to 154 mmHg (P=0.046). No changes were observed in the cardiac index, stroke volume index and heart rate. An unchanged TT score index (9.9 vs. 10.2 mm, P=0.428) and GLPSS (14.3 vs. 14.5%, P=0.658) indicated preserved LV global systolic function and unchanged E'/A' (0.95 vs. 0.89, P=0.110) and E/E' ratio (15.4 vs. 14.9, P=0.612) indicated unchanged diastolic function. CONCLUSION: Sufentanil preserves hemodynamic parameters as well as echocardiographic indices of LV systolic and diastolic function in patients with ischemic heart disease (IHD).

Variation in use of peroperative inotropic support therapy in cardiac surgery: time for reflection?

BACKGROUND: There is no well-established evidence-based clinical guidelines on the most appropriate use of peroperative inotropic support in cardiac surgery. We aimed to identify patient- and procedure-related factors associated with the use of peroperative inotropic support and to estimate physician-level variation. METHODS: A population-based study using data from the Western Denmark Heart Registry on 3585 consecutive cardiac surgery cases from three university hospitals. Inotropic support was defined as infusion of inotropic drugs or nor epinephrine at the separation from cardiopulmonary bypass. Poisson's regression modelling was used to determine predictors of inotropic support and to compare use of high-dose inotropic support among experienced cardiac anaesthesiologists. RESULTS: We identified a range of factors that were independently associated with an increased use of inotropic support therapy including pre-operative left ventricular dysfunction, pre-operative renal dysfunction, complex procedures, prior cardiac surgery, emergency surgery, pre-operative pulmonary hypertension, critical pre-operative state, extended extra corporal circulation-time and female gender. Further, we found substantial variation in use of inotropic support both at hospital- and at physician-level. The adjusted odds ratio of high-intensity inotropic support varied significantly at physician level from 2.3 [95% confidence interval (CI) 1.83-2.71] to 0.3 (95% CI 0.15-0.61) when the individual physicians were compared with the rest. CONCLUSION: The use of inotropic support during cardiac surgery is associated with the pre-operative state of the patient, as well as type of surgery. However, the present study indicates that use of peroperative inotropic support is also highly dependent on physician's preferences, indicating the need for an evidence-based approach when initiating inotropic therapy in cardiac surgery.

Ketamine reduce left ventricular systolic and diastolic function in patients with ischaemic heart disease.

OBJECTIVE: Ketamine may be followed by a general increase in haemodynamics and oxygen consumption, which may be of concern in patients with ischaemic heart disease. The purpose of this study was to evaluate the effect of ketamine on left ventricular (LV) systolic and diastolic function by different modalities of echocardiography and tissue Doppler imaging in patients with ischaemic heart disease. METHODS AND RESULTS: Prospective observational study of 11 patients acting as own control based on echocardiographic imaging before and after bolus ketamine 0.5 mg/kg. Simpson's 2 D-volumetric method was used to quantify left ventricular volume and ejection fraction. General global LV deformation was assessed by Speckle tracking ultrasound, systolic LV longitudinal displacement was assessed by Tissue Tracking score index and the diastolic function was evaluated from changes in early-(E') and atrial (A') peak velocities during diastole. Average heart rate (34%) and blood pressure (35%) increased significantly after ketamine (P<0.0001). Mean tissue tracking score index decreased from 11.2 ± 2.3 to 8.3 ± 2.6 (P=0.005) and Global Speckle tracking 2D strain from 17.7 ± 2.7 to 13.7 ± 3.6 (P=0.0014) indicating a decrease in LV global systolic function. The E'/A' ratio decreased from 1.11 ± 0.43 to 0.81 ± 0.46 (P=0.044) indicating impaired relaxation. CONCLUSION: Different modalities of echocardiography in combination with tissue Doppler indicate both diminished systolic and diastolic function after ketamine administration in patients with ischaemic heart disease.

High thoracic epidural analgesia improves left ventricular function in patients with ischemic heart.

BACKGROUND: In patients with ischemic heart disease, high thoracic epidural analgesia (HTEA) has been proposed to improve myocardial function. Tissue Doppler Imaging (TDI) is a tool for quantitative determination of myocardial systolic and diastolic velocities and a derivative of TDI is tissue tracking (TT), which allows quantitative assessment of myocardial systolic longitudinal displacement during systole. The purpose of this study was to evaluate the effect of thoracic epidural analgesia on left ventricular (LV) systolic and diastolic function by means of two-dimensional (2D) echocardiography and TDI in patients with ischemic heart disease. METHODS: The effect of a high epidural block (at least Th1-Th5) on myocardial function in patients (N=15) with ischemic heart disease was evaluated. Simpson's 2D volumetric method was used to quantify LV volume and ejection fraction. Systolic longitudinal displacement was assessed by the TT score index and the diastolic function was evaluated from changes in early (E'') and atrial (A'') peak velocities during diastole. RESULTS: After HTEA, 2D measures of left ventricle function improved significantly together with the mean TT score index [from 5.87 +/- 1.53 to 6.86 +/- 1.38 (P<0.0003)], reflecting an increase in LV global systolic function and longitudinal systolic displacement. The E''/A'' ratio increased from 0.75 +/- 0.27 to 1.09 +/- 0.32 (P=0.0026), indicating improved relaxation. CONCLUSION: A 2D-echocardiography in combination with TDI indicates both improved systolic and diastolic function after HTEA in patients with ischemic heart disease.

Cardiac surgery patients present considerable variation in pre-operative hemodynamic variables.

BACKGROUND: It is essential to control hemodynamics in cardiac surgery. Patients are often monitored extensively in order to optimize hemodynamic performance. However, pre-operative values are normally unknown. Furthermore, hemodynamic goals may seem arbitrary and the lack of an evidence-based consensus may lead to both under- and over-treatment. The aim of this study was to evaluate the variables most commonly used for hemodynamic guidance in the post-operative period. METHODS: Ten patients scheduled for elective cardiac surgery were followed with invasive hemodynamic monitoring the night before surgery. All data were recorded automatically and electronically. RESULTS: We found considerable inter-patient differences and intra-patient variation. The greatest intra-patient variation was found in the cardiac index (CI), ranging from 1.9 to 5.3 l/min/m(2). Four patients had periodic CI <2.4 l/min/m(2). Eight patients showed SpO2 values < or =92, four of them in more than 15% of the observations. Six patients had an SvO2 <70% in more than 40% of the observations and two an SvO2 < 64% in more than 20% of the observations. CONCLUSIONS: This study is unique because hemodynamic reference data in cardiac surgery patients have not been published previously. The intra-patient variations were unexpectedly high in most hemodynamic variables and demonstrate the difficulties of using hemodynamic parameters as a guidance for treatment and indicate that goal-oriented therapy using currently accepted values may result in over-treatment in some patients.

Perioperative feasibility of imaging the heart and pleura in patients with aortic stenosis undergoing aortic valve replacement.

BACKGROUND: The postoperative monitoring and treatment of the patient undergoing aortic valve replacement is a complex challenge. Echocardiography is the only method which provides dynamic and real-time bedside imaging of the heart. Focused assessed transthoracic echocardiography has been shown to provide a usable window for cardiac imaging in a mixed ICU population. The aim of this study was to evaluate the feasibility of perioperative imaging of the heart and pleura according to the focused assessed transthoracic echocardiography protocol in patients scheduled for aortic valve replacement. METHOD: Thirty-five adult patients scheduled for aortic valve replacement were followed perioperatively with focused assessed transthoracic echocardiography examinations. A Vivid-7 echo-machine and a 2.5 MHz matrix transducer with second-harmonic imaging were used for data acquisition. The image quality for the cardiac window was graded 1-5 (1 = no image, 2 = poor and unusable image quality, 3 = usable image quality, 4 = good image quality and 5 = perfect image quality). A score >or=3 equalled an image quality judged to be of sufficient quality to be interpreted and thereby to contribute to clinical decision-making. RESULTS: All patients had at least one usable window preoperatively. At least one usable window was obtained in 88% of patients on the first postoperative day, and in 97% at discharge. The image quality changed over time, with the poorest quality being observed on the first postoperative day. The apical view with the patient in the left lateral position provided the best cardiac window on all occasions. The presence of drains did not significantly affect the achievability of a satisfactory examination. The number of patients with pleural effusion was relatively high. On the first postoperative day, 10 subjects had unilateral and one subject had bilateral pleural effusions. At discharge, 14 patients had unilateral and four patients had bilateral effusions. CONCLUSIONS: We conclude that the image quality of the heart and pleura, according to the focused assessed transthoracic echocardiography concept, is sufficient to undergo interpretation and thereby contribute to the perioperative clinical decision-making in patients with aortic stenosis.

The influence of propofol and midazolam/halothane anesthesia on hepatic SvO2 and gastric mucosal pH during cardiopulmonary bypass.

OBJECTIVE: Because propofol is known to reduce vascular resistance, the objective of this study was to compare the indices of hepatosplanchnic circulation and oxygenation during cardiopulmonary bypass (CPB) in patients anesthetized with either propofol or midazolam/halothane. DESIGN: A prospective, randomized, nonblinded study. SETTING: A university hospital. PARTICIPANTS: Twenty patients undergoing cardiac surgery with CPB. INTERVENTIONS: Nine patients were anesthetized with propofol/fentanyl/pancuronium and 11 patients were anesthetized with midazolam/halothane/fentanyl/pancuronium. All patients had a nasogastric tonometer tube and two fiberoptic thermodilution catheters inserted; one in the pulmonary artery and one in the upper right hepatic vein. During bypass, SvO2s were measured from the venous line of the heart-lung machine. MEASUREMENTS AND MAIN RESULTS: Gastric mucosal pH (pHi) was measured prebypass, 30 minutes after the start of CPB, and just before weaning off CPB. Hepatic SvO2 (HSvO2) values were recorded every 5 minutes. The pH gap was less at 30 minutes of hypothermic CPB in the propofol group. In the midazolam/halothane group, the HSvO2 decreased after the start of rewarming, whereas in the propofol group the values remained almost at the prebypass levels. At the end of rewarming, the HSvO2 was almost identical in the two groups. CONCLUSION: Propofol preserved the HSvO2 during CPB and produced a more optimal relationship between the hepatosplanchnic blood flow and oxygen consumption.

Perioperative metoprolol reduces the frequency of atrial fibrillation after thoracotomy for lung resection.

OBJECTIVE: The association of atrial fibrillation with thoracic surgical procedures is well known, but nevertheless its cause is not well defined. Increased sympathetic activity may play a role in the development of atrial fibrillation, and reduced beta-receptor activity may be advantageous. The objective was to evaluate the effect of oral beta-blockade on the frequency of atrial fibrillation and to evaluate some possible causative factors. DESIGN AND SETTING: The study was prospective, randomized, and double-blind, and was conducted at Aarhus University Hospital. PARTICIPANTS: Thirty patients without previous or present cardiovascular history undergoing elective thoracotomy for lung resection. INTERVENTIONS: The patients received either 100 mg of metoprolol or placebo orally before surgery and once daily postoperatively. Anesthesia consisted of a thoracic epidural block combined with general intravenous anesthesia. Epidural morphine was continued postoperatively. MEASUREMENTS AND MAIN RESULTS: Patients were monitored with electrocardiograms (ECGs), capillary pulse oximetry, invasive hemodynamic monitoring, central venous oxygen saturation, arterial blood gases, serum electrolytes, and fluid balances. Atrial fibrillation developed in 23.3% of the patients, 6.7% after metoprolol compared with 40% in the placebo group. Atrial fibrillation developed a mean of 2.9 days postoperatively. The predominant hemodynamic findings were perioperative lower oxygen consumption and postoperative lower cardiac index after metoprolol. Patients developing atrial fibrillation had much higher oxygen consumption and postoperative cardiac index than other patients. CONCLUSION: Perioperative oral beta-blockade can reduce the frequency of atrial fibrillation without serious side effects. Increased sympathetic activity is one of the predominant factors in the cause of this complication.

[Continuous measurements of cardiac output in the perioperative period]. / Kontinuerlig måling af hjertets minutvolumen i den perioperative periode.

Management of critically ill patients is based on knowledge of fundamental physiological variables. Automatized and continuous measurement of these variables is preferable. A new system based upon the thermodilution method has been developed to measure cardiac output automatically and continuously. We evaluated the system in the potentially unstable perioperative period with possible great and rapid changes in cardiac output. Twenty patients, scheduled for open heart or abdominal aortic aneurysm surgery, were included into the study, which was approved by the local ethical committee. The patients were monitored for up to 30 hours. At random intervals five iced bolus thermodilution cardiac output (BCO) determinations were made and compared to the continuous measurements (CCO). Two hundred and thirty-one pairs of data were obtained. The cardiac outputs ranged from 2.5-14.9 l/min. The absolute bias was 0.31 l/min (95% limits of agreement -1.4 l/min to 2.0 l/min). The mean relative error was 4.7% with a standard deviation of the relative error of 15.4%. The linear regression was represented by: CCO = 11.352 x BCO - 0.36. The correlation coefficient R was 0.90 (p < 0.001). In conclusion, the CCO measurement technique is a promising clinical method. The method is straightforward, requires no calibration, is independent of vascular geometry and measures with its limitations volumetric flow. Finally automatic and continuous patient monitoring provides more information and has potential to reveal previously undetected haemodynamic events.

Preoperative metoprolol improves cardiovascular stability and reduces oxygen consumption after thoracotomy.

BACKGROUND: Increased sympathetic activity perioperatively and associated cardiovascular effects play a central role in cardiovascular complications. High thoracic epidural blockade attenuates the sympathetic response, but even with complete pain relief, haemodynamic and endocrine responses are still present. Beta-adrenoceptor blockade is effective in situations with increased sympathetic activity. This study was designed to evaluate the perioperative haemodynamic effect of preoperative beta-blockade and its influence on the haemodynamic aspects of the surgical stress response. METHODS: Thirty-six otherwise healthy patients undergoing elective thoracotomy for lung resection were randomised double-blinded to receive either 100 mg metoprolol or placebo preoperatively. Anaesthesia was combined high thoracic epidural block and general anaesthesia. The epidural analgesia was continued during recovery. Patients were monitored with ECG, pulse oximetry, invasive haemodynamic monitoring, arterial blood gases and electrolytes. RESULTS: After induction of anaesthesia the mean arterial pressure (MAP) decreased in both groups, and decreased further in the placebo group after initiation of the epidural block. The heart rate (HR) was slightly less throughout the observation period after metoprolol. Peroperatively, the only difference in measured haemodynamics was a marginally higher MAP after metoprolol. Postoperative cardiac index (CI) was lower with a lower variability and cardiac filling pressures were slightly higher in the metoprolol group. The oxygen consumption index was higher after placebo throughout the observation period, with no difference in the oxygen delivery. CONCLUSION: We found that preoperative beta-blockade during combined general anaesthesia and high thoracic epidural blockade stabilised perioperative HR and CI and decreased total oxygen consumption.

[Atrial fibrillation after coronary artery bypass surgery. The significance of preoperative vagus modulation and ectopic atrial activity]. / Atreiflimren efter koronar bypass-kirurgi. Betydningen af proeoperativ vagusmodulation og ektopisk atrieaktivitet.

To investigate the impact of pre-operative autonomic balance and atrial ectopic activity on the risk of atrial fibrillation or flutter after aorto-coronary artery bypass surgery 24-hour Holter monitoring was analyzed in 102 patients before coronary artery bypass grafting. Index for vagal tone was calculated as % successive RR-interval differences > 6%. Twenty-nine (28%) of the 102 patients developed atrial fibrillation or flutter. Independent predictors (90% confidence interval) of postoperative atrial fibrillation or flutter were identified by logistic regression analysis: the independent predictors were older age, relative risk 1.07/year (1.02-1.12), vagal index < 10%, relative risk 4.50 (1.40-14.5), > or= 10 ectopic supraventricular beats/24 hour, relative risk 3.03 (1.05-8.72), and one or more event of non-sustained supraventricular tachycardia, relative risk 3.02 (1.11-8.22). Thus, age of the patient, attenuated preoperative cardiac vagal modulation, ectopic supraventricular beats, and paroxysmal non-sustained supraventricular tachycardia are independent risk factors for the development of atrial fibrillation or flutter after coronary artery bypass surgery.

[Cesarean section in severe double valvular disease]. / Sectio ved svaer toklapsygdom.

During pregnancy haemodynamic changes are a stress to the cardiovascular system. Women with previously asymptomatic cardiovascular disease may develop life-threatening cardiac failure because of the extra demands of pregnancy. Early diagnosis, close control and treatment during pregnancy, delivery and the postpartum period are essential. We report a case where a woman with a mitral stenosis and insufficiency of the mitral and aortic valves gave birth to a child by caesarian section.

Contamination of central venous catheters. The skin insertion wound is a major source of contamination.

In a prospective controlled trial we compared the rates of catheter-tip contamination in central venous catheters inserted with or without skin contact. The study was designed so that each patient was their own control. All patients had a single-lumen central venous catheter and a Swan-Gantz sheet inserted through the skin. A Swan-Gantz catheter was inserted and retracted through the sheet thus avoiding contact with skin or subcutaneous tissue. Catheter-tip cultures were performed on removal of catheters. Thirty-three Swan-Gantz catheters were cultured and all were sterile. In the corresponding 33 sheets 16 (48.6%) yielded bacterial growth. Four of the sheets showed growth of more than 15 cfu. In the 26 single-lumen catheters, eight (30.8%) catheter-tips grew bacteria, and four of them had more than 15 colonies. The study supports the theory that the skin-insertion wound is a major source of catheter-contamination.

Continuous cardiac output measurements in the perioperative period.

Management of critically ill patients is based on knowledge of fundamental physiologic variables. Automatized and continuous measurement of these variables is preferable. A new system based upon the thermodilution method has been developed to measure cardiac output automatically and continuously. We evaluated the system in the potentially unstable perioperative period with possible great and rapid changes in cardiac output. Twenty patients, scheduled for open heart or abdominal aortic aneurysm surgery, were included in the study, which was approved by the local ethical committee. The patients were monitored up to 30 hours. At random intervals five, iced, bolus thermodilution cardiac output (BCO) determinations were made and compared to the continuous cardiac output measurements (CCO). Two hundred and thirty-one pairs of data were obtained. The cardiac outputs ranged from 2.5-14.9 l.min-1. The absolute bias was 0.31 l.min-1 (95% limits of agreement -14 l.min-1 to 2.0 l.min-1). The mean relative error was 4.7% with a standard deviation of the relative error of 15.4%. The linear regression was represented by: CCO = 1,1352.BCO-0.36. The correlation coefficient R was 0.90 (P < 0.001). In conclusion, the CCO measurement technique is a promising clinical method. The method is straightforward, requires no calibration, is independent of vascular geometry and measures with its limitations volumetric flow. Finally automatic and continuous patient monitoring provides more information and has potential to reveal previously undetected haemodynamic events.

The effect of metoprolol upon blood pressure, cerebral blood flow and oxygen consumption in patients subjected to craniotomy for cerebral tumours.

Hypertension and cerebral hyperperfusion are often seen in the immediate postoperative period after craniotomy for supratentorial tumours. Metoprolol is known to attenuate the postoperative hypertensive response after hypotensive anaesthesia and this study was carried out to evaluate the effect of metoprolol on cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) before extubation and cerebral arteriovenous oxygen content difference (AVDO2), mean arterial blood pressure (MABP), PaO2 and PaCO2 in a 180-min period after extubation. Twenty patients anaesthetized with thiopentone, fentanyl, nitrous oxide 67%, and halothane 0.5% were randomized to receive intravenous metoprolol or placebo at the end of the peroperative period. There were no significant differences in CBF- and CMRO2 values between the two groups. In the period between closure of the dura and 5 min after extubation, an increase in MABP was observed in the control group (P < 0.05), but not in the metoprolol group. During the same period a decrease in AVDO2 was observed in both groups (P < 0.05); during the next 10 min an increase was observed, but with no difference in AVDO2 values between the groups. A higher level of PaO2 in the metoprolol group was observed in the postoperative period. These findings suggest that peroperative treatment with metoprolol reduces postoperative MABP but does not influence the cerebral blood flow and metabolism.

Contamination of central venous catheters: use of infusion-lines does not increase catheter-contamination.

In a prospective controlled trial we compared the rates of intraluminal contamination between the two lumens of a double-lumen central venous catheter. One lumen was used for repeat infusions and injections, and the other was permanently connected to a slow infusion of 0.9% NaCl. The study was designed so that the patient was his own control. Twenty-eight catheters were examined and comparison with catheter-tip cultures was performed in 24. Intraluminal culture was performed 67-77 h after insertion of the catheter and catheter-tip culture was performed on removal of the catheter. The contamination rate from catheter-tips was 20.8%, which is acceptable compared with other studies. There was only one positive intraluminal culture in each group (3.6%), and thus no correlation was found between contamination rate and the number of times the infusion-line had been interrupted for use. As for catheter-tip contamination, we found no correlation between infusion of blood-products or parenteral nutrition and contamination rates.