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Simultaneous measurements of extracellular pH, potassium (K(+)), and calcium (Ca(2+)) activity might be indicative of myocardium vitality or ischemia. Ten consecutive patients undergoing elective coronary artery bypass grafting were studied. Epicardial extracellular pH, potassium, and calcium were measured by a miniaturized disposable multi-sensor probe. Blood gases and electrolytes were derived with measurements of arterial and mixed venous blood samples at intervals during surgery. The mean epicardial baseline levels for pH in all patients were 8.04+/-0.22 arbitrary units (AU) for the right ventricle (RV) and 8.03+/-0.21 AU for the left ventricle (LV); for Ca(2+) 0.23+/-0.07 mmol/l (RV) and 0.20+/-0.10 mmol/l (LV); and for K(+) 4.54+/-1.51 mmol/l (RV) and 4.38+/-0.57 mmol/l (LV). Before ischemia, epicardial pH was moderately (p

Introduction: Recent innovations in laser scanning technology provide a potentially useful tool for three-dimensional surface registration for image-guided surgery. The purpose of this study is to evaluate the clinical reliability of this technique in oral and maxillofacial surgical procedures using image-guided navigation. Methods: In an experimental step, a stable anthropomorphic skull model with prelabeled markers was scanned and registered with laser surface scanning (z-touch®, BrainLAB) and marker-based algorithms. The registration protocol was then repeated 25-times. Root mean square error (RMSE) and target difference values were compared for their suitability for this application. Twelve patients with different indications for oral and maxillofacial surgery were planned for image-guided surgery using a passive infrared surgical navigation system (VectorVision®, BrainLAB). Preoperative computed tomography (CT) scans were carried out with newest 16-line multisclice CT-scanner (Siemens Somatom Sensation 16). The new markerless laser surface scanning technique was applied in all intraoperative patient registrations. Registration error was noted. The clinical application accuracy was determined for anatomical landmark localization deviation. Results: In the experimental protocol a mean registration error (RMSE) or target difference of 1.3 (0.14) or 2.08 (0.49) mm for laser scanning and 0.38 (0.01) or 0.99 (0.15) mm for marker registration was found. The differences for RMSE and target localization were statistically significant (p

BACKGROUND This study was undertaken to investigate the physiological effects of cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) on cerebral oxygen metabolism estimated by near-infrared spectroscopy (NIRS). METHODS Ten newborn piglets (2.1 to 2.6 kg) were monitored with right frontal NIRS; the right jugular bulb was cannulated for intermittent sampling of jugular venous blood. All animals underwent CPB, cooling to a core temperature below 15 degrees C, 60 minutes of DHCA followed by subsequent reperfusion and rewarming. Continuously recorded NIRS data and intermittent jugular venous blood values were compared. RESULTS NIRS performance was examined over the jugular venous oxygen saturation (SjvO2) range of 40 to 98 %, a linear correlation was found between SjvO2 and NIRS-derived regional cerebral oxygen saturation (rSO2) (r = 0.91, p < 0.001). A correlation was observed between the cellular oxidation NIRS-parameter cytochrome oxidase aa3 (CytOx) slope during the DHCA period in relation to rectal and nasopharyngeal temperature immediately before the onset of DHCA (r = 0.75 and 0.85, p < 0.001). CONCLUSIONS This study suggests that NIRS-measured hemoglobin oxygenation parameters may reflect functional changes in cerebral hemodynamics and brain tissue oxygenation, while CytOx values represent related effects on intracellular oxidative metabolism.

Early detection of myocardial ischaemia is a central problem in cardiological and cardiosurgical intensive care. A new approach is the use of ion-selective electrodes implanted directly on the myocardium, enabling detection of increased potassium activity as an indication of general hypoxia. After a comprehensive study of the electrode parameters, an animal experiment was carried out, in which it was found that respiration-induced hypoxia resulted in an increase in epicardial potassium activity (p < 0.01). Blood gas analysis performed simultaneously revealed reduced arterial pO2, but no acidosis. Haemodynamic data evidenced hypoxic depression of circulatory parameters. Histological examinations of the myocardium beneath the electrodes revealed typical lymphocytic infiltration. Electron microscopy demonstrated crystolysis in the mitochondria as an early sign of hypoxia, thus confirming the sensitivity of these electrodes. This underscores the potential of ion-selective electrodes for the detection of myocardial ischaemia, and they should now be investigated in the clinical setting.

Advances in intra-operative imaging and the development of new minimally invasive techniques are having an ever greater impact on modern surgery. Mobile CT scanners in the operating room is a new technique that permits image-guided surgery, and helps minimize postoperative complications. We report on our initial experience with intraoperative CT scanning during surgery on patients suffering lateral midface trauma. A mobile CT unit, the Tomoscan M (Philips, Utrecht, Netherlands) set up in the operating room, was evaluated in 6 patients with zygomatic bone fractures. The patients were placed on the CT scanner table, which is detachable from the gantry. The unit is powered by batteries charged from an ordinary ring mains supply via a conventional plug. The CT images obtained were of good quality in all cases. No technical problems were observed during surgery. Using repeat CT scans, the procedure also permits accurate intraoperative monitoring of the anatomical repositioning of the bone fragments, and accurate implantation. No intraoperative or early postoperative complications were observed. This new technical aid ensures highly accurate reduction of the bone fragments, and minimizes the need for reoperation. High-quality intraoperative imaging with surgical navigation increase surgical outcome, and expand the spectrum of minimally invasive surgery.

The use of minimally invasive procedures in maxillofacial surgery will require new technologies involving surgical navigation and techniques. The aim of our studies is to improve the efficacy of image-guided navigation in combination with endoscopically assisted techniques for minimally invasive craniomaxillofacial procedures. Prospective evaluation was made of all patients who underwent surgical procedures using image-guided navigation. The most common type of operations performed were endoscopically assisted interventions within the paranasal sinuses, fracture treatment, the resection of bone lesions and further miscellaneous interventions. Our experience to date suggest that image-data based techniques are eminently applicable, providing a feasible alternative to conventional surgical treatment.

The purpose of this prospective clinical study was to evaluate new resorbable implants for bone fixation. The plates and screws are made of poly (D, L)lactide (PDLLA). Bioresorbable osteosynthesis and fixation (ResorbX) has been applied in 22 patients. Indications for operations were craniofacial trauma (malar, orbital-floor or frontal bone fractures) or orthognathic procedures (Le Fort-I-osteotomies) as well as the surgical correction in case of craniofacial syndromes. In the initial follow up, the first patients showed clinically and radiologically uneventful fixation and healing of the bone. There were no implant material related complications. Overall, the advantages of PDLLA-implants appear to be their ease of use, radiolucency and resorption, although further experience is needed to determine the longterm benefits of biodegradable implants.

Objective: Recent observations have been shown that the induction and accumulation of heat shock proteins (HSPs) by short exposure to nonlethal whole-body hyperthermia with normothermic recovery are closely associated with transient resistance to subsequent ischemiareperfusion challanges. Here, this study was performed to investigate whether a shortly heat shock pretreatment affects the left ventricular (LV) function after cold cardioplegic ischemia in reperfused neonatal rabbit hearts. Methods: Hearts from neonatal New Zealand White rabbits were isolated perfused (working heart preparation) and exposed to 2 h of cold cardioplegic ischemia followed by reperfusion for 60 min. To induce the heat shock response neonatal rabbits (na 5, HT-group) were subjected to whole-body hyperthermia at 42.0‐42.58C for 15 min, followed by a normothermic recovery period of 60 min, before harvesting and the onset of global hypothermic cardioplegic arrest. Another set of hearts (na 5, control group) without a heat treatment underwent a similar perfusion and ischemia protocol served as control. The postischemic recovery was assessed by measuring several parameters of LV function. LV biopsies from all control and heat treated animals were taken before ischemia and at the end of reperfusion to examine myocardial HSP levels by Western blot analysis. Results :A t 60 min of reperfusion the HT-group showed significant better recovery of ventricular function such as LV developed pressure (DP) (74.6 ^ 10 vs. 52.1 ^ 8.5%, P , 0.05), LV positive dP/dt (910 ^ 170 vs. 530 ^ 58 mmHg/s, P , 0:01) and LV end-diastolic pressure (LVEDP) (8 ^ 2 vs. 18.4 ^ 5 mmHg, P , 0:05) than control. Myocardial oxygen consumption (MVO2) was significantly higher in the HT-group compared with control (0.054 ^ 0.006 vs. 0.041 ^ 0.002 ml/g per min, P , 0:05). Significant postreperfusion lower level in lactate production was observed in the HT-group (0.83 ^ 0.11 vs. 1.67 ^ 0.8 mmol/l, P , 0:05). Also, the recovery of hemodynamic parameters such as aortic flow, coronary flow and cardiac output was significantly superior (P , 0:05) in the HT-group. Furthermore, high expression of HSP72 1 /73 1 were detected in the myocardial tissue samples of heat-treated rabbits by immunoblotting, appearing even at 60 min of normothermic recovery after heat stress. Conclusions: These data in the immature rabbit heart indicate that previous shortly heat treatment with high level expression of heat shock proteins (HSP72 1 /73 1 ) before hypothermic cardioplegic ischemia provides transient tolerance against myocardial injury and could be an improvement for the postischemic functional recovery of neonatal hearts. q 2000 Elsevier Science B.V. All rights reserved.

In der vorliegenden Studie wurde ein Kaninchenmodell verwendet, um den Einflus eines 60minutigen Kreislaufstillstandes in tiefer Hypothermie auf die intrakraniellen Veranderungen in der Verfugbarkeit von Sauerstoff im Hirngewebe sowie die Hindurchblutung untersuchen zu konnen. Mit der Dauer des totalen Kreislaufstillstandes nahm der Hirngewebe-Sauerstoffpartialdruck (ptiO2) kontinuierlich ab. In der Reperfusion und Erwarmung war die zerebrale Reoxygenierung mit subnormalen ptiO2-Werten stark verzogert. Am OP-Ende (nach Reperfusion und Entwohnung von der EKZ) ergaben sich signifikant verminderte Werte fur den ptiO2: 25±4 mmHg vs. Ausgangswert: 38±5 mmHg (p

Using a dual channel near infrared (NIR) in vivo optical spectroscopy (INVOS) system (INVOS 3100A, Somanetics Corp. Troy, MI, USA) we investigated the relationship between jugular venous oxygen saturation (SjvO2) and regional cerebral oxygen saturation (rSO2) in 30 infants and children (mean age 4.5 years) with congenital heart disease undergoing cardiac catheterisation. The NIRS-SomaSensor (emitter and dual receiver probe) was applied at a standardised right fronto-temporal location (over the right frontal cortex) on the infant's head and covered with an adhesive flexible bandage. Using NIR light (730 and 810 nm) and two source-detector spacings (3 and 4 cm from the transmitter), percentage values of rSO2 were calculated from detected haemoglobin saturations. Simultaneously, jugular venous oxygen saturation (SjvO2) monitoring was performed via a catheter placed in the right internal jugular vein with its tip positioned in the jugular bulb, as verified by fluoroscopy. To compare the reliability of NIRS measurement characteristics, jugular venous blood was analysed for SjvO2 as a reference measure of global cerebral oxygenation, by co-oximetry (OSM3-Hemoximeter, Radiometer Copenhagen, Denmark). Other measured variables included pulse oximetry, arterial blood pressure, and venous and arterial oxygen saturations. Over a jugular venous oxygen saturation range of 31-83%, a significant positive linear correlation was found between rSO2 (NIRS measurement) and SjvO2 (jugular bulb oximetry) (r = 0.93, p < 0.001). No significant correlation was observed between rSO2 values and arterial blood saturation or pulse oximetry. The quantitative correlation between rSO2 (haemoglobin oxygenation in a small hemi-elliptical area of the brain) and reference SjvO2 measurement (method for monitoring global cerebral oxygenation) suggests that NIRS measurement with subtraction algorithm should identify predominantly intracranial saturation in the pediatric age group, and will tend to reflect global oxygenation under physiological conditions. Transcranial oximetry using dual receiving channel NIRS offers a noninvasive, real-time, reliable and practicable means of monitoring cerebral haemoglobin oxygenation changes infants and children with cyanotic and noncyanotic congenital heart disease.

Currently, no reliable minimally invasive method of measuring cardiac output continuously in neonates and children undergoing cardiac surgery is available. An extravascular Doppler probe was used to measure cardiac output in 15 New Zealand White rabbits (average weight 3.5 kg, range 2.5-4.5 kg). The results obtained were compared with cardiac outputs determined using the aortic thermodilution principle. The mean cardiac outputs measured with the extravascular Doppler probe was 0.37 +/- 0.01 l/min as compared with 0.39 +/- 0.01 l/min with aortic thermodilution. Regression analysis revealed a close correlation (r = 0.973) between the two techniques. The extravascular Doppler techniques is an option for continuous and reliable cardiac output measurement in small animals used in surgical experiments (open chest models) and in neonates or children during surgical repair of complicated congenital heart conditions.

There is currently no efficient and reliable clinical means of assessing the degree of ischemia- and reperfusion-associated damage in microvascular transplants. The objective was to study correlation of tissue oxygen tension measurements with tissue oxygen saturation, cytochrome oxidase redox state, and tissue viability.Latissimus dorsi muscle was dissected and mobilized in New Zealand white rabbits (n = 30, 2.5 ± 0.5 kg). Muscles were exposed to warm ischemia in two groups with either 4 or 6 h, followed by reperfusion. Tissue PO(2) was measured with a miniature intramuscular oxygen sensor (Licox microprobe; Integra Neurosciences, Ratingen, Germany) all along with tissue hemoglobin saturation (rSO(2)) and cytochrome oxidase aa3 redox state (CytOx) by in vivo near-infrared spectroscopy. Linear correlation was performed between tissue PO(2) and rSO(2), CytOx and tissue viability.After ischemia and reperfusion, tissue PO(2) and CytOx recovery was significantly decreased in both groups compared with control (4 h: P0.05; 6 h: P0.01). Significant correlations between changes in tissue PO(2) and rSO(2) (r = 0.92; P0.01), CytOx (r = 0.90; P0.01), wet-to-dry ratio (r = -0.97; P0.01), and mitochondrial viability index (r = 0.97; P0.01) were found.Tissue oxygen tension measured with microprobes correlated closely with tissue oxygenation, cellular oxygen utilization, and the extent of ischemia reperfusion injury.

Simultaneous measurements of extracellular pH, potassium (K(+)), and calcium (Ca(2+)) activity might be indicative of myocardium vitality or ischemia. Ten consecutive patients undergoing elective coronary artery bypass grafting were studied. Epicardial extracellular pH, potassium, and calcium were measured by a miniaturized disposable multi-sensor probe. Blood gases and electrolytes were derived with measurements of arterial and mixed venous blood samples at intervals during surgery. The mean epicardial baseline levels for pH in all patients were 8.04+/-0.22 arbitrary units (AU) for the right ventricle (RV) and 8.03+/-0.21 AU for the left ventricle (LV); for Ca(2+) 0.23+/-0.07 mmol/l (RV) and 0.20+/-0.10 mmol/l (LV); and for K(+) 4.54+/-1.51 mmol/l (RV) and 4.38+/-0.57 mmol/l (LV). Before ischemia, epicardial pH was moderately (p

Conflicting results have been reported with regard to the neuroprotective effects of steroid treatment with cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA). We evaluated the mode and severity of neuronal cell injury in neonatal piglets after prolonged DHCA and the possible neuroprotective effect of systemic pretreatment (>6 h before surgery) with large-dose methylprednisolone (MP). Nineteen neonatal piglets (age

Myocardial hypoxia is accompanied by increased epicardial potassium activity. In this experimental study in rabbits (n = 13), with ion-selective probes, we correlated our findings with an exact evaluation of myocardial oxygen tension, hemodynamic data and arterial and venous blood gas analysis. The epicardial potassium activity had good correlation with these parameters (pm = −0.95, pco = −0.93 and pa = −0.72, pv = −0.96, respectively). Therefore, the clinical use of these electrodes can be recommended for continuous monitoring in intensive care units.

Background Recent findings indicate that molecular chaperones actively participate in myocardial cytoprotection. Moreover, ischemic tolerance can be induced in humans by brief ischemic events. Therefore, we investigated patients with severe angina attacks before coronary artery bypass grafting. We focused on appearance of anti-hsp70 antibodies as an immunologic response to heat shock protein induction by ischemia followed up by hemodynamic measurements perioperatively. We correlated these clinical findings with the presence of antibodies against hsp70 and the antioxidative capacity of patients' sera. Methods Thirty-five consecutive patients with coronary artery disease scheduled for coronary artery bypass grafting were included. Seventeen patients had severe angina, and 18 patients suffered from chronic stable angina preoperatively. In the patients' sera, antibodies against hsp70 were detected by enzyme-linked immunosorbent assay, and antioxidative capacity was detected using the chromogen assay. Cardiac output and pulmonary capillary wedge pressure were measured using a thermodilution catheter. We also evaluated C-reactive protein and creatine kinase MB isoenzyme, and performed a conventional leukocyte count. Results The sera of the 17 patients with severe angina attacks before surgery contained antibodies against hsp70 and a low antioxidative capacity. The interval between a severe angina attack and anti-hsp70 antibody titer are inversely correlated. These patients had better cardiac output and lower pulmonary capillary wedge pressure values after surgery. Conclusions Severe angina before cardiac surgery coincided with an improved outcome as measured by hemodynamic variables as compared with chronic stable angina. This finding correlated significantly with a low antioxidative capacity and the presence of antibodies against hsp70. These pathophysiologic mechanisms might therefore play a role in myocardial protection.

Perioperative cardiac dysfunction may be related to inadequate myocardial protection during cardiopulmonary bypass (CPB) and associated procedures. Many intrinsic and extrinsic factors may act directly on vessels or indirectly by release of vasoactive metabolites to alter vascular tone and myocardial function during reperfusion. Milrinone, by inhibiting cAMP-specific phosphodiesterase enzymes in both cardiac and vascular smooth muscle, is a powerful inotrope and vasodilator, but has little effect on systemic arterial blood pressure. The purpose of the study was to investigate the effect of milrinone administration on recovery of left ventricular (LV) function and systemic haemodynamics after deep hypothermia and CPB in rabbits.

We investigated the capacity of heat stress to improve myocardial tolerance and cardiac energy metabolism in the isolated perfused neonatal rabbit heart subjected to prolonged cold cardioplegic ischemia.

Recent studies have shown a relation between altered myocardial function and the cardiac cellular changes that are noted with hypothermic cardioplegic arrest, such as energy store depletion and intracellular acidosis. The aim of the study was to evaluate the link between myocardial energy metabolism (high-energy phosphorylated compounds and intracellular pH), as measured using 31phosphorus nuclear magnetic resonance spectroscopy (31P-MRS) and myocardial tissue oxygen pressure (ptiO2) in isolated rabbit hearts subjected to 2 h of cold cardioplegic ischaemia and reperfusion.