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Biomedical subjects

M Hübler

Publications and source records attributed to M Hübler.

At least 19 recordsLinked to original sources
PubMed2002

Cerebral oxygen monitoring during neonatal cardiopulmonary bypass and deep hypothermic circulatory arrest.

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.

Animals↗
PubMed2001

[DDD-pacemaker implantation in a 7-week-old infant: epicardial electrodes in intrapleural position].

Permanent pacing for complete heart block in newborns and small infants is a challenge concerning the mismatch between body size and pacemaker dimensions. As the abdominal position of the large pacemaker carries a considerable risk of healing disturbances, the intrapleural position of single chamber pacemakers is accepted as well. We report about a 7 week old infant with congestive heart failure due to a complete atrioventricular septal defect. The immature valve tissue led to recurrent, severe mitral valve incompetence and necessitated several valvuloplasty procedures and finally the implantation of a mechanical prothesis. Because of a postoperative complete heart block, a dual chamber pacemaker with epicardial steroid-eluting bipolar leads was implanted without specific fixation into the right pleural cavity during delayed sternal closure to ensure atrioventricular synchrony. Despite the capacious implant, adverse effects on hemodynamics and pulmonary function were not observed and the infant thrived normally. The DDD function of the pacemaker allowed the utilization of the infant's complete heart rate spectrum without restrictions due to the technically limited upper tracking rate of 180 bpm.

Age Factors↗
PubMed2001

A comparison of five solutions of local anaesthetics and/or sufentanil for continuous, postoperative epidural analgesia after major urological surgery.

BACKGROUND AND OBJECTIVE: The aim of the present study was to compare and assess the quality of analgesia, the safety and the side-effects after the use of a continuous, thoracic epidural infusion of sufentanil (5 microg h(-1)), 0.25% bupivacaine (10 mL h(-1)), 0.2% ropivacaine (10 mL h(-1)) alone or in combination in patients who had undergone major urological surgery. This prospective, randomized, double-blinded study investigated the efficacy of thoracic epidural infusions after major urological surgery. METHODS: Patients received a 72-h continuous infusion (10 mL h(-1)) of 0.25% bupivacaine (B), 0.2% ropivacaine (R), 0.25% bupivacaine with 0.5 microg mL(-1) sufentanil (BS), 0.2% ropivacaine with 0.5 microg mL(-1) sufentanil (RS) or 0.5 microg mL(-1) sufentanil only (S). The analysis included 109 patients. RESULTS: The mean visual analogue scale (VAS) scores for pain were highest in the groups R and S (P < 0.001). The PaCO2 values were significantly higher in the groups RS and S (P = 0.003). Motor block occurred more frequently in the groups B and BS than in the other groups (P < 0.001). Sedation, nausea and pruritus were more common in the groups that received sufentanil. CONCLUSIONS: A continuous, epidural infusion with these drugs was safe and effective in our patients. The combination of 0.2% ropivacaine plus sufentanil appeared preferable because of the low incidence of motor block.

Aged↗
PubMed2001

Effects of vaporized perfluorocarbon on pulmonary blood flow and ventilation/perfusion distribution in a model of acute respiratory distress syndrome.

BACKGROUND: Perfluorocarbon (PFC) liquids are known to improve gas exchange and pulmonary function in various models of acute respiratory failure. Vaporization has been recently reported as a new method of delivering PFC to the lung. Our aim was to study the effect of PFC vapor on the ventilation/perfusion (VA/Q) matching and relative pulmonary blood flow (Qrel) distribution. METHODS: In nine sheep, lung injury was induced using oleic acid. Four sheep were treated with vaporized perfluorohexane (PFX) for 30 min, whereas the remaining sheep served as control animals. Vaporization was achieved using a modified isoflurane vaporizer. The animals were studied for 90 min after vaporization. VA/Q distributions were estimated using the multiple inert gas elimination technique. Change in Qrel distribution was assessed using fluorescent-labeled microspheres. RESULTS: Treatment with PFX vapor improved oxygenation significantly and led to significantly lower shunt values (P < 0.05, repeated-measures analysis of covariance). Analysis of the multiple inert gas elimination technique data showed that animals treated with PFX vapor demonstrated a higher VA/Q heterogeneity than the control animals (P < 0.05, repeated-measures analysis of covariance). Microsphere data showed a redistribution of Qrel attributable to oleic acid injury. Qrel shifted from areas that were initially high-flow to areas that were initially low-flow, with no difference in redistribution between the groups. After established injury, Qrel was redistributed to the nondependent lung areas in control animals, whereas Qrel distribution did not change in treatment animals. CONCLUSION: In oleic acid lung injury, treatment with PFX vapor improves gas exchange by increasing VA/Q heterogeneity in the whole lung without a significant change in gravitational gradient.

Algorithms↗
PubMed2000

Combination of balanced and regional anaesthesia for minimally invasive surgery in a patient with myasthenia gravis.

A 45-year-old man with cryptorchism, who was known to suffer from generalized myasthenia gravis, was admitted to hospital for surgical treatment using laparoscopy. Such minimally invasive surgery requires good muscle relaxation. However, the use of neuromuscular blocking agents in patients with myasthenia gravis may lead to prolonged apnoea after operation, thus necessitating mechanical ventilation of the lungs. We used a combination of general anaesthesia (with desflurane), and epidural anaesthesia (with the amide local anaesthetic ropivacaine) to obtain excellent abdominal relaxation during surgery. Tracheal extubation was possible immediately after the operation and no adverse effects were observed. The patient was discharged from hospital on the second day after operation. The combination of regional and general anaesthesia for minimally invasive surgery in this patient permitted safe anaesthetic management.

Abdomen↗
PubMed2000

Protein S-100beta in brain and serum after deep hypothermic circulatory arrest in rabbits: relationship to perivascular astrocytic swelling.

The aim of this study was to evaluate the relationship between the kinetic patterns of the protein S-100beta, an astroglial cell marker, and its immunohistochemical expression in the brain in rabbits that underwent cardiopulmonary bypass with deep hypothermic circulatory arrest. Fourteen New Zealand rabbits (weight, 3.1+/-0.25 kg) were anaesthetised, intubated and mechanically ventilated. Four animals were not connected to the cardiopulmonary bypass and served as controls. Ten animals were perfused according to a uniform protocol. After systemic cooling, deep hypothermic circulatory arrest was induced for 60 minutes. After reperfusion and rewarming, the animals were weaned from bypass and sacrificed. In the brain, astrocyte reactivity for S-100beta was evaluated immunocytochemically (DPC Immustain) and the serum concentrations of S-100beta were analysed using a commercially available immunoluminometric kit (Byk-Sangtec, Dietzenbach, Germany). In all experimental animals a significant increase of the serum concentration of the protein S-100beta was found immediately after reperfusion and the termination of cardiopulmonary bypass. In comparison with the control animals, increased staining of S-100beta was found in the astroglial cells and swollen astrocytic end-feet in the perivascular regions. There were fewer signs of neuronal cell injury of neurones in the hippocampus structure. In conclusion, astrocytic activation and S-100beta overexpression seems to precede the neurodegeneration following deep hypothermic circulatory arrest. The marked perivascular cell swelling may support the assumption of reperfusion injury of the astroglial cell complex that forms the blood-brain barrier, which may be indicative of the source of the released S-100beta into the blood stream.

Animals↗
PubMed2000

Annular stabilization in mitral repair without a prosthetic ring.

BACKGROUND AND AIM OF THE STUDY: Annular stability is not guaranteed after mitral repair without a prosthetic ring. We introduce a newly developed plication technique and detail its stabilizing effect on the mitral annulus after Gerbode plasty. METHODS: Patients suffered degenerative mitral valve prolapse with chordal rupture restricted to the middle scallop of the posterior leaflet. Between 1986 and 1997, 102 patients underwent Gerbode plasty with or without annular reinforcement with a pericardial strip or modified Paneth plasty (group C). The mean (+/- SD) follow up was 70.4 +/- 41.1 months. Since 1996, 32 patients have undergone a newly developed annuloplasty technique (group N), where a pericardial strip was tightly anchored to the bilateral trigones and posterior annulus, which was folded by Gerbode plasty. With the final anchoring suture the intention was to prevent plication breakdown of this portion. Mean follow up for this group was 17.6 +/- 7.1 months. Progression of mitral regurgitation after surgery in both groups was studied. RESULTS: In group C, postoperative progression of mitral valve regurgitation occurred in 41.1% of patients (5.9% to grade 1, 17.6% to grade 2, 17.6% to grade 3). Among these patients, reoperation was due to plication breakdown of the Gerbode plasty in six cases (5.9%), and to either chordal rupture or annular dilatation in 10 cases each (9.8%). In contrast, no reoperation due to recurrent severe mitral regurgitation was needed in group N. Progression of mitral regurgitation after surgery was seen in six patients (two to grade 1; four to grade 2). CONCLUSION: The newly developed annuloplasty technique may be useful in stabilizing the mitral annulus after Gerbode plasty.

Adolescent↗
PubMed1999

Medium-term results of heart transplantation using donors over 63 years of age.

BACKGROUND: The continual shortage of hearts for transplantation (HTx) led to the expansion of the donor pool by accepting older donors. We compared the medium-term follow-up of patients after HTx with older hearts (over the age of 63 years) with those of patients after HTx with younger hearts. PATIENTS AND METHODS: Since April 1994 we have used hearts for HTx from donors older than the age of 63 years. Until November 1998, 309 HTx and 9 re-HTx were performed in 309 adults with a mean age of 50.7+/-10.9 years (range 17-68 years). There were 252 men and 57 women. The patients were divided into two groups: group I--donor age under 63 years (296 patients, mean age 50.4+/-11 years; mean donor age 38.1+/-13 years; mean follow-up 1.7+/-1.6 years); group II-donor age of more than 63 years (13 patients, mean age 57.4+/-5.6 years; mean donor age 65.1+/-2.1; mean follow-up 2.2+/-1.6 years). There were no differences in the etiology of heart failure, gender, or ischemia time between the groups. The patients in group II were significantly older (P = 0.008). Multiple factors were analyzed in the groups, which included changes in the left/right ventricle ejection fraction, early postoperative mortality (up to 30 days), cumulative survival rates and cardiac-dependent morbidity [myocardial infarction, malignant arrhythmias, coronary stenosis (>50% in one of the main coronary arteries) and transplant vasculopathy]. Additionally, freedom from cytomegalovirus infection (rise of titer or seroconversion) and freedom of acute rejection episodes grade > or =2 (International Society of Heart & Lung Transplantation [ISHLT]) were analyzed. RESULTS: After 1 year mean left and right ventricle ejection fraction were good in both groups and did not significantly change for up to 2 years. No Re-HTx was performed in group II. The early postoperative mortality was similar in both groups (P = 0.8). Also, the cumulative survival rates were similar in both groups (P = 0.87). Long-term cardiac morbidity was lower in group I (P = 0.03). The long-term freedom from cytomegalovirus infection in group I was significantly higher when compared with group II (P = 0.0002). The long-term freedom from severe rejection episodes was similar in both groups (P = 0.3) CONCLUSION: The study found a significant increase in long-term cardiac morbidity due to more focal coronary stenosis in group II, and freedom from cytomegalovirus infection, but did not find significant differences in the long-term survival between patients who received hearts from donors of up to 63 years of age and from those more than 63 years. The acceptance of donors older than 63 years old for HTx does not worsen the outcome of the recipients. The careful selection of older donors, with close monitoring of the coronary situation after HTx and expanded indications for revascularization of older hearts, could make HTx with older hearts, even in older recipients, a safe option.

Adolescent↗
PubMed1999

Vaporized perfluorocarbon improves oxygenation and pulmonary function in an ovine model of acute respiratory distress syndrome.

BACKGROUND: Perfluorocarbon liquids are being used experimentally and in clinical trials for the treatment of acute lung injury. Their resemblance to inhaled anesthetic agents suggests the possibility of application by vaporization. The authors' aim was to develop the technical means for perfluorocarbon vaporization and to investigate its effects on gas exchange and lung function in an ovine model of oleic acid-induced lung injury. METHODS: Two vaporizers were calibrated for perfluorohexane and connected sequentially in the inspiratory limb of a conventional anesthetic machine. Twenty sheep were ventilated in a volume controlled mode at an inspired oxygen fraction of 1.0. Lung injury was induced by intravenous injection of 0.1 ml oleic acid per kilogram body weight. Ten sheep were treated with vaporized perfluorohexane for 30 min and followed for 2 h; 10 sheep served as controls. Measurements of blood gases and respiratory and hemodynamic parameters were obtained at regular intervals. RESULTS: Vaporization of perfluorohexane significantly increased arterial oxygen tension 30 min after the end of treatment (P < 0.01). At 2 h after treatment the oxygen tension was 376+/-182 mmHg (mean +/- SD). Peak inspiratory pressures (P < 0.01) and compliance (P < 0.01) were significantly reduced from the end of the treatment interval onward. CONCLUSION: Vaporization is a new application technique for perfluorocarbon that significantly improved oxygenation and pulmonary function in oleic acid-induced lung injury.

Animals↗
PubMed1999

Validation of fluorescent-labeled microspheres for measurement of relative blood flow in severely injured lungs.

The aim of the study was to validate a nonradioactive method for relative blood flow measurements in severely injured lungs that avoids labor-intensive tissue processing. The use of fluorescent-labeled microspheres was compared with the standard radiolabeled-microsphere method. In seven sheep, lung injury was established by using oleic acid. Five pairs of radio- and fluorescent-labeled microspheres were injected before and after established lung injury. Across all animals, 175 pieces were selected randomly. The radioactivity of each piece was determined by using a scintillation counter. The fluorescent dye was extracted from each piece with a solvent without digestion or filtering. The fluorescence was determined with an automated fluorescent spectrophotometer. Perfusion was calculated for each piece from both the radioactivity and fluorescence and volume normalized. Correlations between flow determined by the two methods were in the range from 0.987 +/- 0.007 (SD) to 0.991 +/- 0.002 (SD) after 9 days of soaking. Thus the fluorescent microsphere technique is a valuable tool for investigating regional perfusion in severely injured lungs and can replace radioactivity.

Acute Disease↗
PubMed1997

Imaging of the orifice of the left ventricular outflow tract: technique and initial results.

The mechanism of left ventricular outflow tract (LVOT) obstruction in the patient after mitral valve replacement or repair was examined with the aid of 2D echocardiography. For the interpretation of the spatial relationship between the aortic root and mitral annulus, however, the 2D display is sometimes inadequate since it may not simultaneously capture these structures in each center. We developed a method to clarify this relationship in 3D based on magnetic resonance images. We defined the office of the left ventricular outflow tract (LVOT orifice), consisting of, in turn, a muscular region, i.e., edge of the interventricular septum, and an annular region, i.e., the annulus of the anterior mitral leaflet. In this paper we present image data obtained from one of eight normal subjects examined and compare this with data of one of two patients who preoperatively suffered degenerative mitral regurgitation and subsequently underwent chordal-preserving mitral valve replacement, in which anterior chordae were reattached to the anterior annulus. In the normal subject, the mitral annulus exhibited a flexible change in shape during the systole, maintaining sufficient LVOT orifice size. In the patient, the prosthetic valve exhibited translational motion during systole, resulting in dynamic LVOT obstruction. This phenomenon was also observed in one other case. Furthermore, the lateral view of the LVOT orifice revealed a projection of the prosthetic valve into the LVOT, causing mechanical LVOT obstruction. The finding that translational motion of the prosthetic valve with an inflexible mitral annulus results in dynamic LVOT obstruction may support the hypothesis that annular rigidity causes dynamic LVOT obstruction after mitral valve repair with a rigid prosthetic ring.

Adult↗