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B Zwissler

Publications and source records attributed to B Zwissler.

At least 19 recordsLinked to original sources
PubMed2006

[Videolaryngoscopy versus direct laryngoscopy for elective endotracheal intubation].

BACKGROUND: We compared the ease of viewing the glottis under direct vision during conventional laryngoscopy with the quality of indirectly viewing on a monitor during laryngoscopy with a Macintosh videolaryngoscope in a multicenter study. PATIENTS AND METHODS: After ethical approval and written informed consent of 300 patients with no anticipated difficult airway, conventional laryngoscopy with a Macintosh videolaryngoscopy blade was performed and the quality of the view of the glottis was assessed and documented according to the Cormack and Lehane scoring system as modified by Yentis and Lee. Subsequently, the indirect viewing conditions on the monitor were documented without changing the position of the blade. Differences between both distributions were analyzed using the Bland-Altman Test. RESULTS: Videolaryngoscopy improved the laryngoscopy score by 1 grade in 72 cases, by 2 grades in 17 cases and by 3 grades in 2 cases. A relevant improvement (from grades III/IV to II) was found in 28 patients. Viewing conditions worsened in 3 cases by 1 grade, in 4 cases by 2 grades and in 3 cases by 3 grades. A statistical analysis of the data gave a bias of 0.31 and an SD bias of 0.77.The 95% confidence interval of the distribution ranged from -1.12 to 1.81. CONCLUSION: Videolaryngoscopy can lead to better viewing conditions but in rare cases it may result in worse viewing conditions.

Adult↗
PubMed2006

[Aprotinin in cardiac surgery: more risks than usefulness?].

Antifibrinolytic therapy with the serine protease inhibitor Aprotinin or the lysine analogues epsilon-aminocapronic acid or tranexamic acid is a therapeutic measure to reduce perioperative blood loss during cardiac surgery. In an international, prospective, non-randomised phase 4 observation study, Mangano et al. investigated the effectiveness and side-effects of Aprotinin, epsilon-aminocapronic acid and tranexamic acid in comparison to no antifibrinolytic therapy in a total of 4,374 patients who underwent cardiac surgery with extracorporeal circulation. In the opinion of Mangano et al. the results of this study question the safety and effectiveness of Aprotinin for reduction of perioperative blood loss by cardiac surgery patients. Despite a critical review of the study and results reported by Mangano et al., the authors of the present paper come to the conclusion that, in view of the availability of more reasonably priced alternatives in Germany, it appears to be sensible to give preference to tranexamic acid instead of aprotinin.

Aminocaproates↗
PubMed2006

[Tolerance to perioperative anemia. Mechanisms, influencing factors and limits].

The expected cost explosion in transfusion medicine (increasing imbalance between donors and potential recipients, treatment of transfusion-associated complications) increases the socio-economic significance of specific institutional transfusion programs. In this context the estimated use of the patient's physiologic tolerance to anemia enables 1) the tolerance of larger blood losses (loss of "diluted blood"), 2) the onset of transfusion to the time after surgical control of bleeding to be delayed and 3) the perioperative collection of autologous red blood cells. The present review article summarizes the mechanisms, influencing factors and limits of this natural tolerance to anemia and deduces the indication for perioperative red blood cell transfusion. Under strictly controlled conditions (anesthesia, normovolemia, complete muscular relaxation, hyperoxemia, mild hypothermia) extremely low hemoglobin concentrations [Hb <3 g/dl (<1.86 mmol/l)] are tolerated without transfusion by individuals with no cardiopulmonary disease. In the clinical routine these situations are limited to borderline situations e.g. unexpected massive blood losses in Jehovah's Witnesses or unexpected shortcomings in blood supply. The current recommendations coincide to the effect that perioperative red blood cell transfusion 1) is unnecessary up to a Hb concentration of 10 g/dl (6.21 mmol/l) even in older patients with cardiopulmonary comorbidity and 2) is only recommended in cases of Hb <6 g/dl (<3.72 mmol/l) in otherwise healthy subjects including pregnant women and children. Critically ill patients with multiple trauma and sepsis do not seem to benefit from transfusions up to Hb concentrations >9 g/dl (>5.59 mmol/l). In cases of massive hemorrhaging and diffuse bleeding disorders the maintenance of a Hb concentration of 10 g/dl (6.21 mmol/l) seems to contribute to stabilization of coagulation.

Anemia↗
PubMed2006

[Perioperative administration of beta-blockers. Critical appraisal of recent meta-analyses].

BACKGROUND: The perioperative administration of beta blockers is a controversial issue. Numerous trials failed to show any significant benefit or disadvantage because of low event rates and insufficient statistical power. METHODS: In July 2005 McGory et al. and Devereaux et al. separately published 2 meta-analyses, raising the question of the perioperative administration of beta blockers for patients undergoing non-cardiac surgery. In February 2006, Schouten et al. published an additional meta-analysis concerning the same question. This evidence is supplemented by the publication of Lindenauer et al. in 2005. These trials will be critically appraised in this review. RESULTS: McGory et al. concluded from their data that the perioperative administration of beta blockers significantly reduced cardiovascular mortality. However, this conclusion is clearly not valid because of methodological deficits of the meta-analysis. In addition, the publications by Devereaux et al. and Schouten et al. did not support the results of the analysis by McGory et al. CONCLUSIONS: There is still no clear evidence to prove a significant benefit for the unselected perioperative use of beta blockers in patients undergoing non-cardiac surgery. While high-risk patients and those undergoing major surgical procedures seem to profit, low-risk patients may be more harmed than helped by this intervention. The fact that 3 meta-analyses raising the same question produced substantially different results, underlines the importance of critically appraising each meta-analysis.

Adrenergic beta-Antagonists↗
PubMed2006

Hyperoxic ventilation increases the tolerance of acute normovolemic anemia in anesthetized pigs.

OBJECTIVE: To investigate the impact of prophylactic hyperoxic ventilation with Fio2 0.6 on the physiologic limit of acute normovolemic anemia. DESIGN: Prospective, controlled, randomized experimental study. SETTING: Experimental animal laboratory of a university hospital. SUBJECTS: Fourteen anesthetized domestic pigs. INTERVENTIONS: Animals were randomly ventilated with either Fio2 0.21 (group 0.21, n = 7) or Fio2 0.6 (group 0.6, n = 7), and acute anemia was induced by isovolemic blood-for-hydroxy-ethylstarch (HES) exchange using a 6% HES solution (130/0.4). MEASUREMENTS AND MAIN RESULTS: The blood-for-HES-exchange was continued until a sudden decrease of total body oxygen consumption indicated the onset of oxygen supply dependency (primary end point); the corresponding hemoglobin (Hb) concentration was defined as "critical" (Hb(crit)). Secondary end points were changes in myocardial function, central hemodynamics, oxygen transport, and tissue oxygenation. Compared with room air ventilation (Fio2 0.21), hyperoxic ventilation with Fio2 0.6 enabled a larger blood-for-HES-exchange (139%, 124/156) of circulating blood volume vs. 87% (68/94, p < .05), until Hb(crit) was reached (1.5 g/dL [1.4/2.1] vs. 2.4 g/dL [2.0/2.8], p < .05). At Hb 2.4 g/dL (i.e., Hb(crit) in group 0.21), animals of group 0.6 still presented with superior oxygen transport, tissue oxygenation, and hemodynamic stability. However, hemodynamic and oxygen transport variables were found deteriorated more severely at Hb 1.5 g/dL (i.e., Hb(crit) of group 0.6) compared with group 0.21 at Hb 2.4 g/dL. CONCLUSION: During cell-free volume replacement, hyperoxic ventilation with Fio2 0.6 generates a readily usable plasmatic oxygen reserve and thereby increases the tolerance toward acute normovolemic anemia.

Anemia↗
PubMed2006

The effect of inhaled nitric oxide and inhaled iloprost on hypoxaemia in a patient with pulmonary hypertension after pulmonary thrombarterectomy.

Acute pulmonary hypertension with life-threatening right heart failure may complicate the postoperative course following cardiothoracic surgery. Both inhaled nitric oxide and inhaled iloprost, a stable analogue of prostacyclin, have been used frequently for this purpose in acute pulmonary hypertension of various origins. We present a case of a patient with acute pulmonary hypertension and severely impaired gas exchange following pulmonary thrombo-endarterectomy. Therapy with one inhaled vasodilator alone did not satisfactorily abort a postoperative pulmonary hypertensive crisis and low-output syndrome due to right heart failure. Combined inhaled nitric oxide and inhaled iloprost, however, showed additive effects. Hence, the combination of both drugs may be reasonable in cases where the standard therapy fails. The effect has been demonstrated by means of continuous blood gas monitoring.

Administration, Inhalation↗
PubMed2005

[Preoperative abstinence from smoking. An outdated dogma in anaesthesia?].

For decades it has been assumed, that smoking within 6 hours of anesthesia and surgery raises the incidence of perioperative cardiopulmonary complications (PPC) including aspiration. Therefore, every patient is advised to stop smoking at the day before surgery, and not to smoke at all at the day of surgery. If the patient does not follow this advice, this will result in a postponement of anesthesia and surgery. The present article aims at re-investigating the scientific basis of this dogma in anesthesia, which virtually forbids smoking at short-term prior to surgery. The influence of short-term (6 h) abstinence from smoking on the perioperative pulmonary morbidity has not been systematically investigated. Interestingly, giving up smoking less than two months prior to surgery does not significantly decrease, but rather may increase the incidence of PPC. With respect to the risk of aspiration, smoking does not increase either the volume or the acidity of gastric juices. A short-lived reduction in the tone of the lower esophageal sphincter is reversible within minutes after termination of smoking. While the emptying of liquid gastric juices is not influenced by smoking, there is a certain delay in the propulgation of solid food. This effect, however, is probably of no clinical relevance in patients, who had their last solid meal the evening before surgery. Hence, we conclude that the anesthesia dogma, which rules out smoking shortly prior to anesthesia, cannot be based on an otherwise increased incidence of pulmonary aspiration or other pulmonary morbidity. However, acute smoking (probably by an increase in COHb) may increase the incidence of myocardial ischemia during exercise and anesthesia. With reference to this possible cardiac complication it still seems reasonable to discourage smoking at least 12 to 48 hours prior to surgery in patients with elevated cardiac risk.

Anesthesia↗
PubMed2005

[Artificial oxygen carriers as an alternative to red blood cell transfusion].

The expected cost-explosion in transfusion medicine (increasing imbalance between donors and recipients, treatment of transfusion-associated complications) increases the socio-economic significance of the development of safe and effective synthetic oxygen carriers as an alternative to the transfusion of allogeneic red blood cells. Currently two types of artificial oxygen carriers have been tested for safety and efficacy in cases of severe anemia otherwise requiring transfusion. Solutions based on human or bovine hemoglobin (HBOC) possess vasoconstrictor properties in addition to their oxygen transport capacity. The impact of vasoconstriction on tissue perfusion and organ function is however not yet fully understood. Nevertheless, in 2001 the bovine HBOC Hemopure was approved in South Africa for treatment of acutely anemic surgical patients. The purely synthetic perfluorocarbon (PFC) emulsions increase the physically dissolved portion of arterial oxygen content. Due to their particulate nature (emulsion droplets) PFCs may only be infused in low doses to avoid overload and malfunction of phagocytic cells of the reticulo-endothelial system. As part of a multimodal blood conservation program (including normovolemic hemodilution and hyperoxia) the low-dose administration of Oxygent effectively increases intraoperative anemia tolerance. Although reduction of perioperative allogeneic blood transfusion has already been demonstrated for HBOC and PFC, the global clinical establishment of artificial oxygen carriers is not to be expected in the near future.

Animals↗
PubMed2005

Positive end-expiratory pressure improves arterial oxygenation during prolonged pneumoperitoneum.

BACKGROUND: Laparoscopic surgery usually requires the use of a pneumoperitoneum by insufflating gas in the peritoneal space. The gas most commonly used for insufflation is carbon dioxide. Increased intra-abdominal pressure causes cephalad displacement of the diaphragm resulting in compressed lung areas, which leads to formation of atelectasis, especially during mechanical ventilation. The aim of this prospective study was to investigate the effect of prolonged intraperitoneal gas insufflation on arterial oxygenation and hemodynamics during mechanical ventilation with and without positive end-expiratory pressure (PEEP). METHODS: Twenty patients undergoing totally endoscopic robot-assisted radical prostatectomy were randomly allocated to one of two groups. In the PEEP group (n = 10) a constant PEEP of 5 cmH(2)O was used, whereas in the ZPEEP group (n = 10) no PEEP was used. RESULTS: Application of PEEP (5 cmH(2)O) resulted in significantly higher P(a)O(2) levels after 3 h (182 +/- 49 vs. 224 +/- 35 mmHg) and 4 h (179 +/- 48 vs. 229 +/- 29 mmHg) of pneumoperitoneum; after desufflation, P(a)O(2) values decreased significantly below preinsufflation values. While there were no significant differences in heart rate, central venous pressure (CVP) and mean arterial blood pressure (MAP) during pneumoperitoneum between both groups, baseline values in CVP and MAP differed significantly between both groups with higher levels in the ZPEEP group. CONCLUSION: The application of a constant positive airway pressure of 5 cmH(2)O preserves arterial oxygenation during prolonged pneumoperitoneum.

Aged↗
PubMed2004

[Levobupivacaine in obstetric analgesia and anaesthesia. Where is its place?].

Levobupivacaine, the S-enantiomer of racemic bupivacaine, will be available in Germany in mid-2004. Pharmacological studies demonstrated that, compared to bupivacaine, levobupivacaine has equal local anaesthetic potency with reduced potential for cardiac and CNS toxicity. This review introduces the new long-acting amide local anaesthetic levobupivacaine to the reader and evaluates its place in obstetric analgesia and anaesthesia compared to bupivacaine and ropivacaine.

Adult↗
PubMed2004

[Indications for blood transfusion during orthopedic surgery].

Ageing of the population increases the number of large orthopedic surgical interventions in elder people. High perioperative blood loss together with a reduced tolerance to anemia increase the transfusion probability in this patient subgroup. The expected cost explosion in the transfusion system (cost intensive quality management, imbalance between the number of donors and recipients) as well as the remaining transfusion related risk of hemolysis, infection and immunosuppression reflect the high socio-economic significance of the development of institutional transfusion programs. The present article summarizes: (1) the (patho-) physiology of anemia compensation, (2) the decision making for transfusion in healthy patients and patients with cardiovascular disease, and (3) the currently applied pre- and intraoperative techniques to reduce allogeneic transfusion in orthopedic patients.

Aged↗
PubMed2004

Effects of standardized acute normovolemic hemodilution on intraoperative allogeneic blood transfusion in patients undergoing major maxillofacial surgery.

The aim of the present study was to demonstrate the practicality and efficacy of acute normovolemic hemodilution (ANH) to reduce allogeneic red blood cell (RBC) transfusion in patients undergoing elective surgery with anticipated high intraoperative blood loss (BL). 124 patients (age 48 +/- 18 years, ASA classes I-III) underwent major maxillofacial surgery in a university hospital (68% tumor surgery, 32% dysgnathia correction). After induction of general anesthesia, ANH was performed by standardized withdrawal of 900 ml (2 units) of whole blood and simultaneous infusion of 500 ml of hydroxyethyl starch solution (6% HES 130,000/0.4) and 1500 ml of crystalloidal solution. Intraoperative BL was fluid-compensated until physiologic parameters indicated the need for RBC transfusion. First, autologous ANH-blood was retransfused followed by, if necessary, allogeneic RBC. Total BL was referred to the patient's calculated blood volume (BV): fractional blood volume loss, BL(fract) = BL/BV. ANH took 16 +/- 2 min and was void of any adverse event. The costs for ANH was 24 per patient. 55 patients had a mean BL(fract) of 44 +/- 28% and required an intraoperative transfusion; 49/55 patients with an average BL(fract) of 37 +/- 14% were transfused with only autologous ANH-blood; 6/55 patients with a mean BL(fract) of 100 +/- 47% underwent additional transfusion with allogeneic RBC. Standardized, 2 unit, ANH is a practicable, safe and economic blood conservation technique that allowed for the complete avoidance of allogeneic RBC transfusion in 89% of patients undergoing maxillofacial surgery that required an intraoperative RBC transfusion.

Adult↗
PubMed2004

Microspheres accurately predict regional bone blood flow.

Even though the microsphere method frequently is used to determinate bone blood flow, validation of this technique for bone blood flow measurement is incomplete. The method is based on the principle that injected microspheres are distributed with the arterial blood and trapped in the capillaries because of their diameter (15 microm). The number of spheres lodged in an organ is proportional to its blood flow. The number of radioactive or fluorescent microspheres in a specific organ is determined indirectly by measuring radioactivity or fluorescence intensity in the organ. In this study the reliability and precision of the microsphere method for determining bone blood flow was established using radioactive and fluorescent microspheres. Six female, anesthetized New Zealand rabbits received left ventricular injections of pairs of fluorescent and/or radioactive microspheres. The humerus, femur, and tibia were dissected in a standardized manner and blood flow was determined in each sample. Comparison of relative blood flow values showed an excellent correlation between radioactive and fluorescent microspheres. The percentage difference and variation between two simultaneously injected sets of microspheres was minimal for radioactive microspheres (0.8% +/- 9.6%) and for fluorescent microspheres (0.2% +/- 11.4%). Regional bone blood flow in different regions of the femur, tibia, or humerus ranged from 2.2-28.1 mL/minute/100 g, but there was no significant difference between right and left bone samples of the same region after repeated measurement. Radioactive and fluorescent microspheres allow precise determination of regional bone blood flow.

Animals↗
PubMed2003

Inhaled nitric oxide induces cerebrovascular effects in anesthetized pigs.

Although inhaled nitric oxide (NO(i)) is considered to act selectively on pulmonary vessels, EEG abnormalities and even occasional neurotoxic effects of NO(i) have been proposed. Here, we investigated cerebrovascular effects of increasing concentrations of 5, 10 and 50 ppm NO(i) in seven anesthetized pigs. Cerebral hemodynamics were assessed non-invasively by use of near-infared spectroscopy and indicator dilution techniques. NO(i) increased cerebral blood volume significantly and reversibly. This effect was not attributable to changes of macrohemodynamic parameters or arterial blood gases. Simultaneously, cerebral transit time increased while cerebral blood flow remained unchanged. These data demonstrate a vasodilatory action of NO(i) in the cerebral vasculature, which may occur preferentially in the venous compartment.

Anesthetics↗
PubMed2003

[Central anticholinergic syndrome and apnea after general anaesthesia. A rare manifestation of the central anticholinergic syndrome].

The central anticholinergic syndrome (CAS) is a rarely observed condition after general anaesthesia. There are no definitive criteria to set the diagnosis of CAS. The syndrome may manifest in clinical neurological signs, such as hyperactive states or a depressed CNS state. The diagnosis usually depends on a process of exclusion of other conditions and is confirmed after rapid recovery following administration of physostigmine. We report on a 34-year-old patient who suddenly lost consciousness and developed respiratory arrest 1 h after general anesthesia and normal postoperative recovery. CAS was considered, although apnea has not been reported as a clinical symptom of this disease up to now and no peripheral signs of CAS were observed. After the administration of 1 mg physostigmine the symptoms resolved immediately and the patient started sufficient spontaneous breathing. However, corresponding to the plasma elimination half-life of the drug, further comatose episodes with apnea occurred. Therefore, the patient was admitted to the ICU and an infusion of physostigmin at a rate of up to 5 mg/h was started. Due to this therapy the patient's state became stable and 15 h after the first manifestation of CAS the infusion of physostigmin was discontinued. The following postoperative course was uneventful. In case of reduced vigilance with apnea after general anaesthesia, central anticholinergic syndrome should be considered. For diagnostic and therapeutic purposes the administration of physostigmine should be attempted.

Adult↗
PubMed2003

[Perioperative implications of heart transplant].

Over the past 30 years, heart transplantation has evolved into a definitive therapy for patients with end-stage cardiomyopathy. However, perioperative management of patients undergoing heart transplantation remains a challenge for anesthesiologists. The presence of biventricular failure, arrhythmias and associated multisystem organ dysfunction may contribute to significant intraoperative hemodynamic instability prior to the initiation of cardiopulmonary bypass (CPB). Even after an uneventful transplantation, weaning from CPB may be difficult. Acute right ventricular failure can develop in the recipient secondary to pre-existing pulmonary hypertension. Treatment options frequently focus on therapeutic interventions directed towards decreasing pulmonary vascular resistance and improving right ventricular contractility. Intraoperative use of transesophageal echocardiography (TEE) enables the anesthesiologist to diagnose acute right ventricular failure early on and guide therapy. Concurrent pathology including kinking of the pulmonary artery anastomosis or valvular insufficiency in the transplanted heart can also be recognized and addressed. The number of patients undergoing cardiac transplantation is continually increasing. In addition, the use of more effective immunosuppressive agents has curtailed transplant rejection and permitted longer survival. Consequently, heart transplant recipients are more frequently presenting for non-cardiac surgical procedures. Thus, an understanding of physiological and pharmacological implications associated with heart transplantation is crucial for managing these patients in the perioperative period.

Adult↗
PubMed2002

[Inhaled vasodilators].

First reports on the use of inhaled nitric oxide (NO) in patients were published in 1991. These reports confirmed data from animal experiments which suggested a selective vasodilatory effect of inhaled NO in pulmonary vessels. As the main clinical effects, both improved oxygenation and a drop of pulmonary artery pressure despite unchanged arterial pressure were observed. Since then, many studies have evaluated the effects of inhaled NO as well as of other aerosolised vasodilators (e.g. PGI(2), PGE(1), nitrates, phosphodiesterase-inhibitors) in patients with pulmonary hypertension, acute right heart failure and/or life-threatening hypoxemia. However, primary pulmonary hypertension of the newborn (PPHN) is the only indication for which inhaled NO has been clinically approved so far. Although an obvious clinical benefit in outcome from inhaled vasodilators has never been formally documented, good clinical efficacy has resulted in an increasing "off label" use of the concept both in Germany and worldwide, particularly with respect to anaesthesia and intensive care medicine. The present article aims to review both the pathophysiological and pharmacological basis of inhaled vasodilators, to critically reevaluate their potential clinical indications and to give a perspective on future developments in the field.

Administration, Inhalation↗