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J H Baumert

Publications and source records attributed to J H Baumert.

14 recordsLinked to original sources
PubMed2002

Increased airway resistance during xenon anaesthesia in pigs is attributed to physical properties of the gas.

BACKGROUND: In this study we investigated the effects of the physical properties of xenon on respiratory mechanisms in pigs. METHODS: With institutional approval, 10 female pigs (mean 25.2 (SD 2.5) kg) were anaesthetized with thiopental, remifentanil, and pancuronium. Gas flow and pressure were recorded continuously at the proximal end of the tracheal tube during constant flow ventilation for control, with 100% oxygen (control), followed by 1.5% isoflurane in 70/30% nitrogen/oxygen, 1.0% isoflurane in 70/30% nitrous oxide/oxygen, and 70/30% xenon/oxygen in random order. Compliance (C) and resistance (R) were calculated using a single compartment model. Resistance was corrected for gas viscosities eta and also for densities pho and viscosities eta as (pho*eta)(1/2) to compare assumptions of laminar and mixed flow in the airways. RESULTS: With constant flow ventilation, xenon increases inspiratory pressure compared with other gas mixtures. There were no significant differences in resistance, corrected for laminar or mixed flow, between the gas mixtures. Xenon anaesthesia did not affect compliance. CONCLUSIONS: The increase in airway pressure observed with xenon anaesthesia is attributed completely to its higher density and viscosity. Therefore, determination of airway resistance must take into account the physical properties of the gas. Xenon does not exert any major effect on airway diameter.

Airway Resistance↗
PubMed2001

[The cardiac risk patient in anesthesia].

Perioperative cardiac morbidity is one of the main challenges to the anaesthesiologist. Because of demographic changes and the increased prevalence of coronary artery disease (CAD) in elderly patients, the number of those at risk is increasing. Special attention has to be paid to patients bearing an increased risk where CAD has not been proven preoperatively because they represent the majority. The use of the "Revised Cardiac Risk Index", which includes patient-related as well as surgery-related risk, is recommended as its predictive value is validated to be very high. Additional preoperative testing is indicated only in those patients at intermediate risk where functional status is poor or unclear. In those with clearly high risk, possibility and urgency of an intervention related to their cardiac disease must be weighed against urgency and invasiveness of planned non-cardiac surgery. Regarding prophylactic perioperative therapy, only beta-blockers can be recommended on a sufficient basis of clinical data. This treatment is of special value in patients with poor functional status and those undergoing vascular surgery. Postoperative continuation of beta blockade for five to seven days is essential to its success. The usefulness of alpha-2-blockers is not equally well-proven so far. Prevention of perioperative hypothermia can reduce cardiac risk. In addition, there is increasing evidence that thoracic epidural anaesthesia decreases cardiovascular morbidity and mortality.

Anesthesia↗
PubMed2001

[A patient with nodal tachycardia after general anesthesia during medication with a selective serotonin reuptake inhibitor].

We report on a 62 year old female patient treated with paroxetine, a selective serotonin reuptake inhibitor, because of an anxiety neurosis undergoing a vaginal hysterectomy in general anesthesia. Apart from a dietary treated diabetes mellitus there were no other diseases. There were no complications during the operation. At the end of the anesthesia an A-V nodal tachycardia appeared which spontaneously changed to a sinus rhythm ten hours after the end of the operation. No clinical or laboratory findings indicated a cardiac ischemia and an additional Holter ECG-Recording showed no further cardiac arrhythmias. No other complications occurred afterwards and the patient was discharged after two weeks. This case report demonstrates clearly that despite a reduced rate of cardiovascular complications compared to other types of antidepressants selective serotonin reuptake inhibitors can lead to perioperative cardiac arrhythmias.

Anesthesia, General↗
PubMed2001

Xenon does not affect human platelet function in vitro.

We sought to determine whether xenon affects platelet glycoprotein expression and platelet-related hemostasis in vitro at a clinically relevant concentration. Human whole blood was stimulated with either adenosine diphosphate or the thrombin receptor agonist peptide (TRAP)-6 after incubation with 65% xenon. Halothane at 2 minimum alveolar anesthetic concentration was used as a positive control. Platelet function and activation were evaluated with two-color flow cytometry. The expression of the platelet glycoproteins GPIIb/IIIa, GPIb, and P selectin were detected with fluorochrome-conjugated monoclonal antibodies. In vitro measurement of platelet-related hemostasis under conditions of high shear stress was performed in citrated whole blood with a platelet function analyzer (PFA-100((R))) by using collagen/epinephrine and collagen/adenosine diphosphate cartridges. Xenon did not affect basal or agonist-induced expression of platelet membrane glycoproteins, activation-dependent conformational changes of the GPIIb/IIIa receptor, expression of P selectin, or PFA closure times. In contrast, halothane reduced TRAP-6-induced activation of the GPIIb/IIIa complex. Furthermore, collagen/epinephrine-induced PFA closure time was significantly prolonged. These results demonstrate that xenon does not affect the unstimulated or agonist-induced platelet glycoprotein expression, activation of GPIIb/IIIa, or platelet-related hemostasis.

Anesthetics, Inhalation↗
PubMed1999

Combining partial liquid ventilation and prone position in experimental acute lung injury.

BACKGROUND: Partial liquid ventilation (PLV) and prone position can improve arterial oxygen tension (PaO2) in acute lung injury (ALI). The authors evaluated additive effects of these techniques in a saline lung lavage model of ALI. METHODS: ALI was induced in 20 medium-sized pigs (29.2+/-2.5 kg body weight). Gas exchange and hemodynamic parameters were determined in both supine and prone position in all animals. Thereafter, one group was assigned to PLV with two sequential doses of 15 ml/kg of perfluorocarbon (n = 10); the second group was assigned to gaseous ventilation (n = 10). Gas-exchange and hemodynamic parameters were determined at corresponding time points in both groups in prone and supine position. RESULTS: In the PLV group, positioning the animals prone resulted in an increase of PaO2 prior to PLV and during PLV with both doses of perfluorocarbon when compared to ALI. PLV in supine position was only effective if 30 ml/kg of perfluorocarbon was applied. In the gaseous ventilation group, PaO2 increased reproducibly compared with ALI when the animals were turned prone. A significant additive improvement of arterial oxygenation was observed during combined therapy with 30 ml/kg of perfluorocarbon and prone position in the PLV group compared with either therapy alone. CONCLUSIONS: The authors conclude that combining PLV with prone position exerts additive effects on pulmonary gas exchange in a saline lung lavage model of ALI in medium-sized pigs.

Animals↗
PubMed1995

[Analysis of heart rate variability. Background, method, and possible use in anesthesia].

BACKGROUND AND METHODS. Small, periodic fluctuations in heart rate are well known to physicians, the respiratory sinus arrhythmia (RSA) being the most easily detectable form of this heart rate variability (HRV). Since it is caused by changing activity of the autonomic nervous system (ANS) controlling heart rate, HRV is investigated to gain information on the functional states of the ANS. Recent developments have led to computer-aided processing of EKG signals based on time and frequency domain methods--the latter using power spectral analysis by fast Fourier or autoregressive algorithms--to exactly describe and quantify HRV. Three major regions in the frequency spectrum between 0.03 and 0.5 Hz (the suitable range for shortterm recordings) have been established: (1) a region around the respiratory rate, usually between 0.2 and 0.35 Hz, called high frequency (HF), (2) a region around 0.1 Hz attributed to vasomotor activity feedback, called low (or mid-) frequency (LF), (3) a peak around 0.04-0.05 Hz correlated to thermoregulation, called very low (or low)frequency (VLF). Power spectral density of HRV is now commonly accepted as a measure of autonomic cardiovascular control activity. By studies on vagal or sympathetic blockade, the HF (or RSA) region has been attributed solely to vagal activity, while both parts of the ANS may contribute to the other two, with, however, the vagal part predominating the resting, healthy individuals. CLINICAL APPLICATIONS/ANAESTHESIA. Thus, spectral analysis of HRV provides a measure for quantifying sympatho-vagal balance in its physiological range. Additionally, reduction of HRV along with cardiovascular disease, including hypertension, myocardial infarction, heart failure and sudden cardiac death, as well as with autonomic dysregulation, has been reported. Since is also a striking reduction produced by most anaesthetic agents, RSA and HRV are investigated as measures of anaesthetic depth. There are contradictory data on the influence of ventilation, medication, and co-existing disease on the spectrum, and thus validation of the method is still to be achieved. It has, however, been proven useful in some studies as a parameter for risk assessment of perioperative or post-infarction cardiovascular complications.

Anesthesia↗
PubMed1993

Perioperative arrhythmia associated with aortic valve stenosis.

Peri-operative arrhythmia is one of the major complications in anaesthesia for valve replacement surgery in patients with aortic stenosis. In this retrospective study, 58 patients with sinus rhythm were investigated from induction of anaesthesia until arrival at the recovery room by close haemodynamic monitoring and Holter ECG recording. After cardiopulmonary bypass (CPB), they received either lidocaine (L, n = 35) or mexiletine (M, n = 23) via infusion for 24 hours. Pre-bypass incidence was 14% for supraventricular (SPBs) and 19% for ventricular serious arrhythmia (VPBs), i.e. high-grade forms which indicate possible deterioration and may require therapy (for all arrhythmia, incidences were 45 resp. 28%). VPBs was independently related to impaired left ventricular function (11 patients) and preoperative digitalis therapy (20 patients) but not to severity of stenosis, serum concentration of potassium (between 3.3 and 5.2 meq/l), or any other clinical parameters. Post-bypass incidence was SPBs 11% and VPBs 33%, the latter representing a significant increase compared to the first period (p < 0.03)--(all arrhythmia: 26 resp. 40%). VPBs was related to the need for multiple therapy including catecholamines and antiarrhythmic agents other than L or M, but no longer to preoperative parameters nor duration of intraoperative ischaemia. Incidences of arrhythmia for L and M were identical. While in these patients digitalis therapy may account for arrhythmia also in general anaesthesia, in valve replacement there is a post-bypass increase in VPBs which is not fully explained. Since the incidence is 33% in spite of anti-arrhythmic therapy, both administered class IB drugs may not be the best therapeutic approach.

Aged↗
PubMed1992

The role of histamine in the cardiovascular effects of atracurium.

We have investigated the effect of a bolus injection of atracurium 0.6 mg kg-1 on the cardiovascular system in 16 patients undergoing aortocoronary bypass surgery. H1- and H2-receptor antagonists were administered to eight patients before the neuromuscular blocker. A standard anaesthetic was used comprising fentanyl, flunitrazepam, etomidate and enflurane. After administration of atracurium, haemodynamic changes and plasma histamine concentrations were measured at frequent intervals. In the first group, who received only atracurium, a brief but marked decrease in SVR and MAP occurred, accompanied by an increase in Cl, together with a marked increase in plasma concentration of histamine. In the second group, who received H1- and H2-receptor block, there was no decrease in MAP and only a small increase in plasma histamine concentration. However, there were significant changes in SVR and Cl similar to those in atracurium group.

Adult↗