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Biomedical subjects

H Guggenberger

Publications and source records attributed to H Guggenberger.

At least 19 recordsLinked to original sources
PubMed2006

Remifentanil or sufentanil for coronary surgery: comparison of postoperative respiratory impairment.

BACKGROUND AND OBJECTIVE: High-dose opioid anaesthesia contributes to decreasing metabolic and hormonal stress responses in patients undergoing cardiac surgery. However, the increase in context-sensitive half-life of opioids given as a high-dose regimen can affect postoperative respiratory recovery. In contrast, remifentanil can be given in high doses without prolonging context-sensitive half-life due to its rapid metabolism. Therefore, we performed a prospective, randomized trial to compare anaesthesia consisting of propofol/remifentanil or propofol/sufentanil with regard to postoperative respiratory function and outcome. METHODS: Patients undergoing coronary artery bypass grafting were randomized to a propofol/remifentanil (0.5-1.0 microg kg(-1) min(-1)) or propofol/sufentanil (30-40 ng kg(-1) min(-1)) based anaesthetic. Carbon dioxide response, forced expiratory volume in one second, vital capacity, and functional residual capacity were measured 1 day prior to the operation, 1 h before extubation, 1, 24 and 72 h after extubation. In addition, the incidence of atelectasis, pulmonary infiltrates, intensive care unit and postoperative length of stay were compared. Patients and physicians were blinded to the treatment group. RESULTS: Twenty-five patients in each treatment group completed the study. There was no difference between patients of the treatment groups regarding demographics, risk- or pain scores. In all patients, carbon dioxide response, forced expiratory volume in one second, vital capacity and functional residual capacity were decreased postoperatively compared to baseline. Patients randomized to remifentanil had less depression of carbon dioxide response, less atelectasis and shorter postoperative length of stay (12 d vs. 10 d) than after sufentanil (P < 0.05). CONCLUSIONS: Intraoperative use of high-dose remifentanil for coronary artery bypass grafting may be associated with improved recovery of pulmonary function and shorter postoperative hospital length of stay than sufentanil.

Aged↗
PubMed2001

Effect of tracheal intubation or laryngeal mask airway insertion on intraocular pressure using balanced anesthesia with sevoflurane and remifentanil.

STUDY OBJECTIVES: To study the effect of tracheal intubation or laryngeal mask airway (LMA) insertion on intraocular pressure (IOP) in strabismus patients undergoing balanced anesthesia with sevoflurane and remifentanil. DESIGN: Open, prospective, randomized study. SETTING: Tertiary care academic medical institution. PATIENTS: 40 adult ASA physical status I and II patients scheduled for elective strabismus surgery. INTERVENTION: Patients were randomized to receive either tracheal intubation or LMA insertion following mask induction with sevoflurane in combination with IV remifentanil. MEASUREMENTS: Intraocular pressure, mean arterial pressure (MAP), and heart rate (HR) were measured before induction, immediately following induction, and after airway insertion. MAIN RESULTS: Intraocular pressure after tracheal intubation or LMA insertion did not differ significantly from preoperative baseline values. Mean arterial pressure and HR did not significantly differ between groups at any time point. CONCLUSIONS: Remifentanil and sevoflurane are not associated with an increase in IOP response during tracheal intubation or LMA insertion above baseline in healthy patients undergoing ophthalmic surgery.

Adjuvants, Anesthesia↗
PubMed2001

[Patient safety and errors in medicine: development, prevention and analyses of incidents].

"Patient safety" and "errors in medicine" are issues gaining more and more prominence in the eyes of the public. According to newer studies, errors in medicine are among the ten major causes of death in association with the whole area of health care. A new era has begun incorporating attention to a "systems" approach to deal with errors and their causes in the health system. In other high-risk domains with a high demand for safety (such as the nuclear power industry and aviation) many strategies to enhance safety have been established. It is time to study these strategies, to adapt them if necessary and apply them to the field of medicine. These strategies include: to teach people how errors evolve in complex working domains and how types of errors are classified; the introduction of critical incident reporting systems that are free of negative consequences for the reporters; the promotion of continuous medical education; and the development of generic problem-solving skills incorporating the extensive use of realistic simulators wherever possible. Interestingly, the field of anesthesiology--within which realistic simulators were developed--is referred to as a model for the new patient safety movement. Despite this proud track record in recent times though, there is still much to be done even in the field of anesthesiology. Overall though, the most important strategy towards a long-term improvement in patient safety will be a change of "culture" throughout the entire health care system. The "culture of blame" focused on individuals should be replaced by a "safety culture", that sees errors and critical incidents as a problem of the whole organization. The acceptance of human fallability and an open-minded non-punitive analysis of errors in the sense of a "preventive and proactive safety culture" should lead to solutions at the systemic level. This change in culture can only be achieved with a strong commitment from the highest levels of an organization. Patient safety must have the highest priority in the goals of the institution: "Primum nihil nocere"--"First, do not harm".

Anesthesia↗
PubMed1999

Functional imaging of the monkey brain.

Functional magnetic resonance imaging (fMRI) has become an essential tool for studying human brain function. Here we describe the application of this technique to anesthetized monkeys. We present spatially resolved functional images of the monkey cortex based on blood oxygenation level dependent (BOLD) contrast. Checkerboard patterns or pictures of primates were used to study stimulus-induced activation of the visual cortex, in a 4.7-Tesla magnetic field, using optimized multi-slice, gradient-recalled, echo-planar imaging (EPI) sequences to image the entire brain. Under our anesthesia protocol, visual stimulation yielded robust, reproducible, focal activation of the lateral geniculate nucleus (LGN), the primary visual area (V1) and a number of extrastriate visual areas, including areas in the superior temporal sulcus. Similar responses were obtained in alert, behaving monkeys performing a discrimination task.

Animals↗
PubMed1998

[Problematic intubation in the patient with laryngeal-hypopharyngeal carcinoma. Retrograde controlled fiber bronchoscopy technique].

Retrograde or fiberoptic intubation techniques are recommended for patients in whom intubation is difficult; however, each method has its own limitations. Good results have been reported with a combination of both techniques, i.e. retrograde passage of a guidewire through the cricothyroid membrane to guide a fiberoptic bronchoscope. The practicality, success and complication rates of our retrograde-guided fiberoptic bronchoscopic technique (RGFT) were studied prospectively in 93 patients with obstructing tumors scheduled for laryngectomy. The techniques showed itself to be successful, practical and safe, with negligible complications in 89/93 patients (96%). The ability to insert the bronchoscope by means of a guidewire and to direct the intubation procedure optically was found to be advantageous. Limitations with extreme obesity and in two other patients with advanced obstructive carcinomas of the larynx. Additionally, use of the tracheal puncture allows the RGFT to be integrated into clinical medical education as a preparatory exercise for emergency coniotomy.

Adult↗
PubMed1998

Effects of the combinations propofol/alfentanil and midazolam/fentanyl on blood pressure and contact phase system during coronary surgery.

Perioperative haemodynamic changes leading to severe circulatory problems during open-heart surgery still represent dreaded complications. The aim of this study was to examine the relationship between the use of applied anaesthetic agents and alterations of the contact phase of the intrinsic blood-clotting system, as changes within the kallikrein-kinin system can lead to a fall in blood pressure. In a randomized study, parameters of the kallikrein-kinin system, coagulation and fibrinolysis were determined for 36 patients with aortocoronary bypass operations. The patients had been given either midazolam/fentanyl or propofol/alfentanil to maintain anaesthesia. Perioperative blood pressure values were registered at seven fixed points. The measured values of the factor XIIa-like activity and the kallikrein-like activity suggested a higher activation of the contact phase, when propofol/alfentanil was given. From the start of the extracorporeal circulation (ECC) to the end of the operation, the kallikrein-like activities in the propofol/alfentanil group were significantly higher than those of the midazolam/fentanyl group. Also, the results of the kallikrein inhibition capacity and the indicators of fibrinolysis (t-PA and D-dimers) indicate a stronger activation of the contact phase--at least at the beginning of recirculation--and as a result of it, a stronger fibrinolysis within the propofol/alfentanil group. In addition, the hypotensive side-effects differed significantly between the two groups. Patients receiving propofol/alfentanil needed the triple amount of antihypotonicum to maintain the mean arterial blood pressure above 75 mmHg. With the results of this study, a correlation between the application of propofol/alfentanil, contact phase activation, with activation of the kallikrein-kinin-bradykinin system and the observed hypotension, can be presumed.

Alfentanil↗
PubMed1995

[Inadvertant suture fixation of a Swan-Ganz catheter to the pulmonary artery following heart surgery].

We report a patient undergoing redo cardiac surgery for combined replacement of the aortic and mitral valves. During the course of the operation, a Swan-Ganz catheter - positioned preoperatively - was accidentally fixed to the wall of the pulmonary artery. As this did not interfere with cardiac output measurement or the pulmonary artery pressure wave form, the fixation was not noticed until an attempt was made to remove the catheter. Fluoroscopy revealed both the catheter's immobility and the location of the suture fixation. The patient required a sternotomy to remove the catheter. In order to avoid this complication, the indications for pulmonary artery catheters during cardiac surgery should be carefully considered. If catheters are inserted, their mobility should by all means be ensured before the chest is closed.

Aged↗
PubMed1995

Variance of cardiorespiratory parameters during gynaecological surgery with CO2-pneumoperitoneum.

Laparoscopic procedures with CO2-pneumoperitoneum are used widely in gynaecology and surgery. The effects of a 15 degrees head-down position, different intra-abdominal pressures (IAP) and CO2-insufflation flows on cardiorespiratory parameters were studied prospectively in 18 gyneacologic patients under general anaesthesia. The 15 degrees head-down position led to significant changes in heart rate (-6%) and in central venous pressure (+53%). Furthermore, significant changes under commonly used conditions for gynaecological laparoscopy (IAP 9mmHg, CO2-insufflation flow 2.41/ min., 15 degrees head-down position) were found in heart rate (+16%), systolic blood pressure (+21%), diastolic blood pressure (+26%), central venous pressure (+57%), peak inspiratory pressure (+26%), end-tidal CO2-concentration (+19%), central venous pCO2 (+21%), and central venous pH (-7%). On examination of variable pressure and insufflation flows (IAP 3, 9, and 15mmHg; CO2-insufflation flows 1.2, 2.4, and 6.0 1/min.), increasing changes in heart rate (7% - 24%), diastolic blood pressure (22% - 33%), central venous pressure (30% - 59%) and peak inspiratory pressure (10% - 43%) correlated with increasing IAP. However, they were independent of CO2-insufflation flows. The results demonstrate that CO2-pneumoperitoneum causes marked changes in cardiorespiratory parameters, but these do not exceed levels commonly regarded as safe in ASA class I and II patients.

Abdomen↗
PubMed1993

Pulmonary venodilation by isoflurane improves gas exchange during Escherichia coli bacteremia.

OBJECTIVE: To determine how isoflurance affects the longitudinal distribution of pulmonary vascular resistance and pulmonary gas exchange during Escherichia coli bacteremia. DESIGN: Prospective, controlled study with open-label assignment of animals to two groups. SETTING: Laboratory. SUBJECTS: Goehingen minipigs. INTERVENTIONS: Induction of acute respiratory failure by a 4-hr infusion of live E. coli bacteria in 12 animals; six animals anesthetized with methohexital/piritramide; six animals anesthetized with isoflurane. The control group consisted of four animals that received the same surgical procedure, but no E. coli infusion. Two animals were anesthetized with methohexital/piritramide and two with isoflurane, respectively. MEASUREMENTS AND MAIN RESULTS: Cardiac output and pressures were measured by means of an arterial catheter, Swan-Ganz catheter, and a left atrial catheter. Effective pulmonary capillary pressure was evaluated graphically from a pulmonary artery occlusion pressure decay. Arterial-alveolar PO2 ratio was calculated to evaluate pulmonary function. Measurements were performed before and after 1, 2, and 3.5 hrs of E. coli infusion. Statistical significance was tested with analysis of variance (ANOVA). E. coli infusion caused hypodynamic shock, an increase in pre- and postcapillary pulmonary vascular resistance and respiratory failure. Postcapillary pressure gradient and effective pulmonary capillary pressure were lower in the isoflurane-group. Methohexital-anesthetized animals developed pulmonary dysfunction after 1 hr of bacteremia, whereas isoflurane-anesthetized animals developed pulmonary dysfunction after 3.5 hrs of E. coli infusion (significantly different, ANOVA, p < .05). There were no significant changes in the sham group. CONCLUSIONS: Isoflurane is a pulmonary venodilator. During lethal E. coli infusion, it ameliorates the increase in pulmonary capillary pressure and preserves pulmonary function until vascular permeability increases.

Administration, Inhalation↗
PubMed1991

Pulmonary artery occlusion-left atrial pressure gradient: an important factor in determining pulmonary venous vascular resistance in acute pulmonary failure.

OBJECTIVE: To determine whether pulmonary artery occlusion pressure (PAOP) accurately reflects left atrial pressure (LAP) in acute pulmonary failure. DESIGN: Sham-controlled laboratory investigation on Goettingen minipigs. INTERVENTIONS: Induction of acute respiratory failure by a 4-hr infusion of live Escherichia coli bacteria in 11 animals; two animals served as the control group. Anesthesia was obtained with methohexital/piritramide and pancuronium bromide. MEASUREMENTS AND MAIN RESULTS: Cardiac output and pressures were measured by means of femoral artery, pulmonary artery, and left atrial catheters. Arterial-alveolar Po2 ratio was calculated to evaluate pulmonary function. Measurements were obtained before and after 1 and 2 hr of the E. coli infusion. Statistical significance was tested with analysis of variance. E. coli infusion caused the hypodynamic shock and respiratory failure. The PAOP-LAP gradient was -0.3 +/- 1.6 mm Hg before bacteremia and increased significantly (p less than .001) to 2.9 +/- 1.8 and 3.4 +/- 2.0 mm Hg after 1 and 2 hr of bacteremia, respectively. No significant changes occurred in the sham group. CONCLUSIONS: A PAOP-LAP gradient may develop during acute respiratory failure. Therefore, pulmonary venous vascular resistance may be underestimated if its determination is based on PAOP. An increase in bronchial to pulmonary blood flow and pulmonary venoconstriction are discussed as hypothetical causes of a PAOP-LAP gradient during acute respiratory failure.

Animals↗
PubMed1990

Pulmonary capillary pressure and gas exchange after E. coli bacteremia in pigs.

In 9 Goettingen minipigs we studied the effect of E. coli bacteremia on effective pulmonary capillary pressure and the longitudinal distribution of pulmonary vascular resistance. Precapillary pressure gradient (dPa) was calculated as the difference between mean pulmonary artery pressure (MPP) and effective pulmonary capillary pressure (Pc) (dPa = MPP-Pc), postcapillary pressure gradient (dPv) as the difference between Pc and left atrial pressure (dPv = Pc-LAP). The disturbance of pulmonary gas exchange was quantified by the AaDO2 quotient 1-PaO2/PAO2. Live E. coli infusion resulted in hypodynamic circulatory failure. Cardiac index fell from 3.7 +/- 0.81 . min-1.m-2 to 2.2 +/- 0.71 .min-1.m-2 after bacteremia lasting for 3.5 h. Simultaneously venous pulmonary vascular resistance rose from 25% of total pulmonary vascular resistance before to 32% after 3.5 h bacteremia, thus raising Pc from 11 mmHg to 16 mmHg. The degree of respiratory insufficiency was correlated with changes of MPP, dPa and dPv: 1-PaO2/PAO2 = 0.2 + 0.035.dPv (r = 0.829). Our results show, that the longitudinal distribution of pulmonary vascular resistance changes during septicemia, thus raising Pc. This may be an important factor in the genesis of septic pulmonary failure.

Animals↗
PubMed1990

[Pulse oximetry: an indicator for the closure of a tracheostome after lateral fixation of the vocal cords (cordopexy)].

The aim of the study was to establish an objective method to predict proper breathing after the closure of the tracheostomy in patients operated upon for laryngeal diplegia by lateral cordopexy. The method is non-invasive, quantitative and independent of the patient. The study covers 18 patients in whom the closure was performed after fixation of the vocal in whom it was performed prior to the operation. The arterial oxygen saturation was measured during closure using a beat-to-beat pulse oximeter and compared with the open tracheostomy, with the closed tracheostomy at rest and under stress, and finally with the closed tracheostomy in the recovery phase. The effort was continued for 5 minutes or until the patient complained of shortness of breath (3 patients). Initially the O2 saturation in these patients did not drop below 90%, but respiratory dependent saturation variations were noted. During the recovery phase, the saturation fell below 90%. The subjective declaration of "asphyxia" always preceded the variations in the O2 saturation. From this, and from the O2 saturation curves, we conclude that the cause for the reopening of the tracheostomy comes more from a circulatory problem that from hypoxemia.

Humans↗
PubMed1989

Acute blood pressure increase during the perioperative period.

Hypertensive reactions occur frequently in the perioperative setting. Perioperative blood pressure elevation is generally amenable to treatment in previously normotensive patients. Alterations in cerebral autoregulation and myocardial performance in chronic hypertension limit the compensatory range available to cope with perioperative blood pressure changes. In cardiovascular or cerebrally compromised patients, the pathophysiology of underlying disease must therefore be taken into account. In the cerebrally compromised patient with space-occupying lesions and even merely locally impaired cerebral autoregulation, any blood pressure increase may reduce cerebral perfusion pressure and cause further cerebral impairment. Furthermore, vasodilation of cerebral vessels must be avoided to prevent further increase in intracranial pressure with reduction of cerebral perfusion. In chronically hypertensive patients, sufficient preoperative antihypertensive therapy is essential to avoid acute perioperative blood pressure elevation. Before antihypertensive pharmacologic therapy is begun, it is essential to rule out all correctable secondary causes of hypertension, particularly impairment of ventilation and oxygen supply. When pharmacologic antihypertensive therapy is necessary, vasodilators (e.g., calcium entry blockers) may be administered to chronically hypertensive patients. If elevated intracranial pressure is the underlying cause of hypertension, cerebral vasodilation must be avoided and only centrally acting antihypertensive agents such as urapidil should be used for management.

Acute Disease↗
PubMed1989

Early detection of inadvertent oesophageal intubation: pulse oximetry vs. capnography.

The aim of our retrospective study was to evaluate the efficacy of routine pulse oximetry and capnometry for detection of oesophageal tube misplacement. Patients undergoing ENT interventions at our hospital are routinely monitored by ECG, arterial blood pressure by cuff, capnography, and pulse oximetry. Beat-to-beat values of Sao2 and CO2 waveform were recorded by a graphic printer connected to a microcomputer, ASA I patients were routinely preventilated with FIO2 = 0.3, and ASA II-III patients with FIO2 = 1.0. Anaesthesia was performed by junior anaesthesiologists under the close supervision of a resident. During a 16-month period, 1372 patients were anaesthetized. The records of 21 patients with accidental oesophageal tube misplacement were available for retrospective evaluation. Nine patients were preventilated with FIO2 = 0.3 (ASA I), 12 patients with FIO2 = 1.0 (ASA II-III). Rapid detection of oesophageal tube position as early as the first ventilation is possible by capnometry, because of the highly significant difference in end-tidal CO2 (0.2 +/- 0.2 vol%; tracheal intubation: 3.7 +/- 0.9 vol.%; P less than 0.0001). The present advanced pulse oximetry method does not permit differentiation between oesophageal and tracheal tube position within 30 s in patients preventilated with FIO2 = 1.0. Oesophageal misplacement was detectable within 7.5 +/- 0.9 s in patients preventilated with FIO2 = 0.3 due to a 2.1 +/- 0.8% decrease in Sao2 (P less than 0.001). Our results underscore the significance of capnometry for rapid detection of inadvertent oesophageal intubation. High-resolution pulse oximetry is a valuable supplement but not a substitute for capnometry.

Carbon Dioxide↗
PubMed1989

[Lung inflation or mechanical ventilation in extracorporeal circulation?].

Extracorporeal circulation (ECC), with its shock-like pulmonary perfusion, leads to pathomorphologic and functional pulmonary changes, the postperfusion syndrome. This study investigated the effects of different types of ventilation during ECC on postoperative pulmonary function and the resulting pulmonary blood gas changes. METHOD. Thirty patients scheduled for aortocoronary bypass surgery were studied. Patients with pre-operative left ventricular end-diastolic pressures exceeding 15 mmHg or signs of right ventricular failure, pulmonary hypertension, or pre-existing pulmonary disease were excluded. The patients were randomly assigned to one of the following three groups: Group 1 (n = 10): static pulmonary inflation during ECC, PEEP 5-10 cm H2O, F1O2 1.0; Group 2 (n = 10): low-frequency ventilation during ECC, rate 10/min, PEEP 5 cm 5H2O, F1O2 1.0; Group 3 (n = 10): medium-frequency ventilation during ECC, rate 120/min, PEEP 5 cm 5H2O, F1O2 1.0. The measurements were made under relative steady-state conditions before the start of surgery and postoperatively after an equilibrium phase of at least 15 min. During ECC using a bubble oxygenator (Bentley BOS 10 S) in moderate hypothermia, blood was aspirated from the pulmonary artery during inflation of the wedge balloon and blood gases were analyzed. Postoperative changes in pulmonary function were evaluated by venous admixture (QVA/Qt); changes in pulmonary vascular resistance after ECC were determined using the pulmonary pressure-flow relationship. RESULTS. In group 1, QVA/Qt rose significantly from 9.6 +/- 2.9% preoperatively to 13.6 +/- 3.5% postoperatively (P less than 0.05, t-test for paired samples). In groups 2 and 3, postoperative QVA/Qt was significantly lower than preoperative QVA/Qt (P less than 0.05; group 2: preoperative 11.9 +/- 3.5%, postoperative 8.1 +/- 2.6%; group 3: preoperative 11.9 +/- 3.0%, postoperative 7.8 +/- 3.2%; Fig. 1). The postoperative pulmonary pressure-flow relationship changed similarly in all three groups (Fig. 2). During ECC, blood aspirated from the pulmonary artery during inflation of the wedge balloon was fully oxygenated with a hematocrit approximating that of arterial blood. In ventilated patients, pO2 during ECC was higher in pulmonary arterial blood than in arterial blood. Pulmonary ventilation during ECC did not lead to pulmonary arterial alkalosis. CONCLUSIONS. Pulmonary ventilation during ECC can prevent a post-operative increase in venous admixture. ECC-related pulmonary vascular changes were not affected by ventilation. Middle-frequency ventilation offers no advantage over low-frequency ventilation during ECC, except that the operating field is more quiet.

Acid-Base Equilibrium↗