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Biomedical subjects

D Kettler

Publications and source records attributed to D Kettler.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Polytrauma following a fall from a great height. The injury pattern and the intensive medicine aspects].

We report on 10 polytraumatised patients who were treated in an ICU after a free-fall injury. The injury pattern of these patients proved to be relatively uniform. Brain oedema occurred in many victims. Remarkable was the fact that 8 out of 10 patients developed a pneumothorax, but only three of them had rib fractures on the same side. All patients suffered from fractures of the extremities with the lower extremities being affected more often. Abdominal injuries were not of importance.

Abdominal Injuries↗
PubMed1992

[Extreme duration of action of diazepam as a cause of respiratory insufficiency in a female geriatric patient].

A 77-year-old woman who had undergone surgery of a non-malignant extracerebral retro-orbital tumor suffered postoperatively from respiratory failure due to impaired respiratory drive and unconsciousness of unknown origin and required artificial ventilation for 14 days. After cerebral and endocrinological causes had been excluded, the residual effects of diazepam were taken into consideration, since the patient had received this substance for premedication and during 3 days postoperatively (total 165 mg). After the application of flumazenil (Anexate), a specific benzodiazepine receptor antagonist, she awoke immediately and was extubated with sufficient spontaneous breathing. The hypothesis that diazepam was the causative agent for the respiratory failure and impaired consciousness was supported by the detection of high serum concentrations of diazepam and its active metabolite desmethyldiazepam. During the following 3 days repetitive injections of flumazenil were necessary to counteract recurring depression of respiration and vigilance. Thereafter further application of flumazenil was not necessary.

Aged↗
PubMed1992

The influence of isoflurane on peri-operative endocrine and metabolic stress responses.

Trauma and surgery profoundly affect the circulating concentrations of metabolites and so-called stress hormones, and may thereby directly or indirectly influence recovery. This stress response on the other hand is subject to modification by the anaesthetics employed. We investigated the effects of isoflurane on selected stress parameters in 10 patients undergoing major abdominal surgery and compared them to those in 10 patients receiving halothane. Plasma levels of adrenaline, noradrenaline, cortisol, ACTH, and beta-endorphin, as well as glucose, non-esterified fatty acids (NEFA), and lactate were determined during a pre-operative anaesthesia period as well as intra- and post-operatively. The levels of all parameters remained stable or decreased during the pre-operative anaesthesia period. They increased intra- and/or post-operatively, reaching peak values in the recovery period. Although the changes in both groups were basically similar, we observed lower serum concentrations of cortisol and lactate in the isoflurane group. We conclude that isoflurane and halothane have similar effects on peri-operative changes of endocrine and metabolic parameters, and that neither can effectively block the stress response to major surgery. We found no firm evidence for a stimulatory effect of isoflurane on the parameters studied.

Adrenocorticotropic Hormone↗
PubMed1992

[The incidence of hypoxia in the immediate postoperative period].

Arterial oxygen saturation (SaO2) was continuously measured using a pulse oximeter in 214 spontaneously breathing adult patients in a recovery room. Hypoxaemia was defined as an SaO2 of 90% or below. The patients were divided into three groups: in group I (n = 83) monitoring was started immediately after arrival in the recovery room, just before oxygen therapy was begun. The patients in group II (n = 106) were observed during and after oxygen therapy. Patients in group III (n = 25), most of whom had regional anaesthesia, were not treated with oxygen in the recovery room. RESULTS. Clinically unexpected hypoxaemia occurred in all three groups: hypoxaemia was observed in 32.6% of patients before oxygen administration (group I). Under oxygen therapy SaO2 was normal in 99.4% of the patients; however, in 30.2% of patients hypoxaemia recurred after oxygen had been discontinued (group II). Hypoxaemic periods were seen in 24% of patients in group III. CONCLUSION. The results indicate the necessity of oxygen administration during transport and in the early postoperative period to all patients. Even during and after regional anaesthesia or brief general anaesthesia, oxygen administration appears to be indicated. Monitoring of SaO2 with a pulse oximeter has become an increasingly standard procedure in modern anaesthesia and should be mandatory.

Adult↗
PubMed1991

[Gas embolism with cardiac arrest during hysteroscopy. A case report on 3 patients].

Hysteroscopy and laparoscopy are relatively non-invasive methods routinely employed in the investigation of infertility. The danger of air embolism during these procedures was recognized early, and carbon dioxide was substituted for air since it is more readily soluble in blood. In this report we describe 3 cases of circulatory collapse and cardiac arrest in healthy young women during routine hysteroscopy (out of a total of 62 patients during the period 1989-1990) which were most probably caused by massive carbon dioxide embolism. Premedication was with oral diazepam 10 mg. Anesthesia was induced with 0.1 mg fentanyl, 2.5 mg droperidol and 100 mg methohexital (100 mg propofol in one case). Intubation was facilitated with 2 mg pancuronium and 50-100mg succinylcholine. Anesthesia was maintained with nitrous oxide 66% and halothane. Ventilation was controlled with a tidal volume of 10 ml per kilogram body weight at a rate of 10 per minute. Monitoring included ECG, automated non-invasive blood pressure, capnometry, pulse oximetry and body temperature. Anesthesia was uneventful prior to insufflation. In each case the signs and symptoms began approximately 5-8 minutes after the start of insufflation and consisted of an initial tachycardia rapidly followed by ventricular dysrhythmias, bradycardia and cardiac arrest. The end-tidal CO2 decreased during the tachycardic phase and prior to asystole. The patients were cyanotic with engorged jugular veins. Resuscitation with closed chest heart massage and intravenous epinephrine or orciprenaline was successful in every case. The typical "mill wheel phenomenon" of gas embolism was audible on auscultation after heart activity had returned, but disappeared after about 5 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Comparison of sufentanil-nitrous oxide anaesthesia with fentanyl-nitrous oxide anaesthesia in geriatric patients undergoing major abdominal surgery.

We have measured haemodynamic changes and plasma concentrations of catecholamines during sufentanil-nitrous oxide and fentanyl-nitrous oxide anaesthesia in a controlled, randomized, double-blind study of 20 geriatric patients (age 65-86 yr) undergoing major abdominal surgery. Fentanyl 7 micrograms kg-1 followed by infusion of 3 micrograms kg-1 h-1 was compared with sufentanil 1 micrograms kg-1 followed by 0.4 micrograms kg-1 h-1. The opioid was supplemented with 60-67% nitrous oxide in oxygen. Haemodynamic changes, plasma concentrations of catecholamines (by high pressure liquid chromatography) and opioids (by radioimmunoassay), and myocardial lactate extraction were measured in the awake state, and at defined times during anaesthesia and surgery. Haemodynamic state was stable during induction and tracheal intubation in both groups, while during stressful operative periods there were increases in mean arterial pressure (17% in the fentanyl group; 11% in the sufentanil group), heart rate (fentanyl 20%, sufentanil 14%) and plasma concentrations of catecholamines (adrenaline: fentanyl 316%, sufentanil 86%; noradrenaline: fentanyl 78%, sufentanil 186%) in both groups. Sufentanil was similar to fentanyl in attenuating the haemodynamic and hormonal responses to surgical stimulation. In two patients in the fentanyl group and three in the sufentanil group, myocardial lactate production was observed temporarily, indicating myocardial ischaemia caused by surgical stress.

Abdomen↗
PubMed1991

Validation of myocardial oxygen demand indices in patients awake and during anesthesia.

An important guideline for anesthesia in patients with ischemic heart disease is the effect on myocardial oxygen demand. Therefore, this investigation evaluated commonly used myocardial oxygen demand formulas for clinical application. The study was performed on patients undergoing coronary bypass surgery (n = 62). Measurements of standard hemodynamics were obtained before and after induction of anesthesia, as well as during sternotomy and after surgery. Coronary blood flow was determined by the argon wash-in technique. In 15 patients, a left ventricular tip manometer was used to accurately assess the first derivative of left ventricular pressure time course. The following indices of left ventricular oxygen demand were calculated: 1) rate pressure product (RPP); 2) tension time index (TTI); 3) pressure work index (PWI) according to the methods of Rooke; and 4) additive parameter (Eg), according to the methods of Bretschneider. All hemodynamic indices of myocardial oxygen demand showed moderate correlation with myocardial oxygen uptake (MVO2) (RPP: r = 0.77; TTI: r = 0.79; PWI: r = 0.79; Eg: r = 0.71). On the average, PWI and Eg led to an underestimation of MVO2 in patients. The constants of the PWI and Eg formulas, which have been developed based on animal experiments, therefore are not directly applicable to clinical conditions. New constants have been derived for PWI by multiple linear regression analysis of the data in the current investigation.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1991

[Mean equipotent blood pressure-lowering concentrations of halothane, isoflurane and enflurane during balanced anesthesia differ from conventional MAC-values].

Balanced anesthesia is a technique that allows control of blood pressure in patients with coronary artery disease. In order to evaluate the relative requirements of volatile anesthetics during basic opioid analgesia, 51 patients with unimpaired left ventricular function who were undergoing coronary artery bypass grafting during balanced anesthesia were investigated. They were randomly assigned to three groups, i.e. halothane (H), isoflurane (I), and enflurane (E). Permanent medications were maintained up to 12 h preoperatively. After premedication with flunitrazepam, promethazine and piritramide, anesthesia was induced with 7 micrograms/kg fentanyl, 0.3 mg/kg etomidate, and 0.1 mg/kg pancuronium and continued with fentanyl infusion (0.1 microgram/kg-1 min-1). Volatile anesthetics were applied in oxygen/air and adjusted to keep the mean arterial blood pressure within +/- 20% of the preoperative value. End-expiratory concentrations of volatile anesthetics were measured (Capnomac, DATEX) and averaged over time. The mean ages of the patients in the different groups were 60 +/- 7.6 years (H), 59 +/- 7.1 years (I), and 60 +/- 6.9 years (E). Four patients in the halothane group, six in the isoflurane group, and five in the enflurane group took beta-blockers preoperatively. The cumulative doses of fentanyl were: H = 0.80 +/- 0.17 mg, I = 0.85 +/- 0.16 mg, and E = 0.83 +/- 0.16 mg at the time of skin incision and H = 1.20 +/- 0.26 mg, I = 1.38 +/- 0.19 mg, and E = 1.24 +/- 0.25 mg at the beginning of extracorporeal circulation.2+ which are possibly the reason for the high O2-MAC value, which may be abolished during balanced anesthesia. However, both the negative inotropic and the vasodilatory effects of enflurane are more likely explanations for the results. It is concluded that 0.5 to 1.0 MAC of halothane, isoflurane, or enflurane used as equipotent components of balanced anesthesia for blood pressure control during aorto-coronary bypass grafting may differ considerably from the conventional MAC concept.

Aged↗
PubMed1991

Haemodynamic and endocrine effects of deliberate hypotension with magnesium sulphate for cerebral-aneurysm surgery.

Deliberate hypotension is widely used during cerebral-artery aneurysm surgery to facilitate clipping and to prevent rupture. A large number of drugs are commonly employed to achieve hypotension, but all have their specific drawbacks. We investigated the effects of magnesium-sulphate-induced hypotension on haemodynamics, as well as on plasma catecholamine and renin concentrations in 11 patients undergoing cerebral-aneurysm surgery. Magnesium sulphate lowered blood pressure by reducing systemic vascular resistance. There was no reflex tachycardia or rebound hypertension, and cardiac output was not decreased. Plasma renin activity increased during hypotension but the inhibitory effects of magnesium on angiotensin converting enzyme prevented angiotensin-II-associated hypertension. Plasma catecholamine concentrations increased moderately during hypotension. Renal perfusion was not impaired since diuresis remained constant or even improved during and after hypotension. Magnesium sulphate in high doses has major drawbacks, however, among which are enhanced neuromuscular blockade and delayed return of consciousness. Although the haemodynamic effects of magnesium sulphate during hypotension appear to be beneficial, these side-effects might limits its usefulness, particularly in neurosurgery. More research must be conducted before magnesium sulphate can be considered a routine method.

Adult↗
PubMed1991

[The energetics and economics of the cardiac pump function].

In anesthesiology and intensive care medicine it is often necessary to treat disorders involving cardiac failure or low-output syndrome. However, in patients who are endangered by ischemic heart disease, any pharmacologic therapy with positive inotropic agents should improve cardiac output without increasing myocardial oxygen demand significantly: the heart should perform its task as efficiently as possible. In the present study a mathematical model of myocardial efficiency was developed. The implications of this theoretical concept of myocardial efficiency were evaluated in animal experiments. THEORETICAL MODEL. Cardiac efficiency is predominantly dependent on preload, afterload, and inotropic state. Quantitatively, it can be calculated from end-diastolic volume, left ventricular systolic pressure (Psyst), stroke volume (SV), and ejection time. The implications of the theoretical analysis are: (1) the inotropic state, which leads to optimal myocardial efficiency, is specifically determined by preload and afterload: for each preload and afterload one matched inotropic state is necessary to achieve optimal efficiency; (2) an increase in blood pressure leads to a decrease in myocardial efficiency even if the inotropic state is optimally matched to preload and afterload; and (3) an increase in end-diastolic volume improves the efficiency of myocardial pump work. ANIMAL EXPERIMENTS. The validity of the theoretical model was studied in animal experiments with emphasis on the following items: (1) is theoretically optimal efficiency of myocardial pump work achieved by physiologic regulation of myocardial performance? (2) how does sympathetic stimulation influence myocardial efficiency? and (3) how do cardiodepressive agents such as beta-blockers or volatile anesthetics influence myocardial efficiency? METHODS. Experiments were performed on nine mongrel dogs after induction of piritramide--nitrous oxide anesthesia. Standard hemodynamics: heart rate, Psyst, maximum left ventricular pressure rise (dP/dtmax), and SV (thermodilution) as well as coronary blood flow (pressure difference catheter) and myocardial oxygen consumption (Fick principle) were measured. In order to create a broad range of different hemodynamic settings, blood withdrawal and retransfusion of blood and/or colloid osmotic solutions were used to modify intravascular volume. Additionally, the inotropic state was varied by infusion of catecholamines (isoproterenol 0.4-0.8 microgram.kg-1.min-1 or norepinephrine 1-2 micrograms.kg-1.min-1). Experimental myocardial failure was induced by adding halothane (0.8-1.5 MAC) to the basic anesthesia, beta-blockade with propranolol (125-250 micrograms.kg-1), and combination of beta-blockade with a pressure load imposed on the myocardium (propranolol 125-250 micrograms.kg-1 + norepinephrine 1-2 micrograms.kg-1.min-1). RESULTS. During variation of the intravascular blood volume by normo-, hypo-, and hypervolemia, the myocardial efficiency very closely matched the theoretically predicted values of optimal efficiency: the average observed efficiency was 98.8% of predicted optimal efficiency. Increasing afterload with norepinephrine did not alter this close relationship, although absolute values of efficiency decreased as predicted by the theoretical model. Application of isoproterenol resulted in SVs that exceeded optimal values by 41.5%. In contrast, during experimental myocardial failure SVs were too small to achieve the necessary values for optimal pump work; observed myocardial efficiency was therefore significantly lower than optimal efficiency. CONCLUSIONS. For pharmacological interventions, it can be concluded that maximal efficiency of cardiac pump work requires maximal end-diastolic filling in combination with minimal afterload. (ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia, Inhalation↗
PubMed1991

[Hemodynamic parameters in the evaluation of myocardial oxygen consumption during anesthesia].

Direct measurements of myocardial oxygen consumption (MVO2) and of a number of hemodynamic variables were performed in 60 patients with coronary heart disease undergoing three-vessel coronary artery bypass surgery. Anesthetic procedures included halothane, enflurane, isoflurane, propofol fentanyl, midazolam/fentanyl, and morphine anesthesia. The following hemodynamic variables were correlated with MVO2: systolic pressure (Psyst), mean arterial pressure (Part), heart rate (HR), cardiac index (CI), stroke volume index (SVI) and arithmetic combined variables: Psyst x square root (HR), Part x square root (HR), Psyst x HR, Part x HR, Psyst x HR x ta(ejection time), Part x HR x ta, Psyst x CI, Part x CI. The product of Psyst x square root (HR) is equivalent to the tension/time index as modified by Bretschneider and the product Psyst x HR x ta is equivalent to the tension/time index of Sarnoff as modified by Robinson. Production and uptake of lactate as metabolic equivalents of myocardial oxygenation were also correlated with myocardial oxygen consumption. Measurements were performed with the patients awake, after induction of anesthesia without surgical stimulation, during sternotomy and after the operation. We obtained 209 evaluable measurements (MVO2 vs hemodynamic variables). The single hemodynamic variables that correlated best with MVO2 was systolic pressure (r = 0.67). Stroke volume index (r = 0.1) and heart rate (r = 0.32) were poorly correlated. The combined hemodynamic variables that correlated most closely with MVO2 were the tension/time indices modified by Bretschneider (Psyst x square root (HR)) and Robinson (Psyst x HR x ta) (r = 0.72). Production and consumption of lactate were not correlated with myocardial oxygen consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Paracetamol test: modification by renal function, urine flow and pH.

Factors which might affect paracetamol disposition have been studied in a heterogenous group of patients in need of mild analgesia in an intensive care unit. Following oral administration of 1 g of paracetamol, plasma and urinary concentrations of the parent compound and metabolites were assessed by HPLC. The renal clearance of paracetamol was significantly correlated with urine flow (r = 0.84) and creatinine clearance (r = 0.77), but not with urine pH. Metabolite output was diminished in patients with reduced renal function. Despite the heterogeneity of patients and the diversity of drug treatment, the urine to plasma paracetamol concentration ratio appeared remarkably constant in patients with normal renal function (9.8 +/- 2.7). It is concluded that the metabolite to paracetamol ratio may only be regarded as a measure of the drug metabolizing capacity in subjects with normal renal function, if factors influencing urine volume and paracetamol absorption are standardized.

Acetaminophen↗
PubMed1990

[Extracardiac risk factors in heart surgery--significance of anesthesia].

Concerning perioperative risk, the choice of anaesthetic is of minor importance in cardiac surgery, whereas concomitant diseases of other organ systems and kind and degree of the cardiac disease can negatively influence the risk. The risk can be reduced by adequate preoperative diagnosis and pharmacotherapy, as well as by perioperative continuation of antianginal and antihypertensive drug treatment. The qualification of the anaesthetist and optimal cooperation between surgeon and anaesthetist are essential for the perioperative patient's management. Careful preoperative medical evaluation and adequate monitoring during operation and postoperative period are further cornerstones to improve outcome as far as the anaesthesiologist's duties are concerned. Old age itself does not enhance the risk, but operative mortality is enhanced in this group due to a higher frequency of multimorbidity and emergency operations, and to more advanced symptoms of heart disease in these patients. The long-term survival of geriatric patients, however, differs not substantially from the expected survivals in this age group, and their quality of life becomes improved to the same extent as in younger patients.

Anesthesia, General↗
PubMed1989

Brachial plexus lesions following cardiac surgery with median sternotomy and cannulation of the internal jugular vein.

There are many possible complications after cannulation of the internal jugular vein (IJV) including injury to the brachial plexus. Neurologic injuries can also occur from sternal splitting. The present study looked at the incidence of brachial plexus lesions after cardiac surgery with and without IJV cannulation. Over 12 months, 815 patients were studied after all types of cardiac surgery. In one half of the group, cannulation of the IJV was avoided when possible. Reducing the incidence of IJV catheterization did not lower the overall incidence of brachial plexus lesions (1.8% to 1.4%). However, there was a higher incidence of neurologic lesions in patients with IJV catheters (3.0% to 0.8%) during the entire study period. All 13 plexus lesions were in the C8-T1 distribution, and seven of the patients had a Horner's syndrome on the same side. No posterior first rib fractures could be detected by radiographs. The brachial plexus lesions were transient but the Horner's syndromes were longer-lasting. It is concluded that the injuries are due to compression and traction of the plexus due to stretching and possibly from hematoma formation from the IJV punctures.

Adult↗
PubMed1989

[Hemodynamic effects of the benzodiazepine antagonist flumazenil following laparotomy under total intravenous anesthesia using midazolam].

Inhalational anesthetic agents, particularly nitrous oxide, are potentially hazardous to both the patient and operating room personnel. Recent efforts have been directed towards the development of intravenous anesthetic techniques using combinations of a hypnotic with an analgesic. The hypnotic used in such a combination should have a short elimination half-life, little or no influence on hemodynamics, and no side effects. Benzodiazepines are likely candidates for total intravenous anesthesia (TIVA) since they combine hemodynamic stability and paucity of unwanted effects with the ability to induce amnesia for the entire perioperative period. They do have long elimination half-lives; even midazolam, the shortest-acting benzodiazepine, has a half-life of 2 to 3 h. This disadvantage might be counteracted by the use of flumazenil, the recently introduced, specifically acting benzodiazepine antagonist. The aim of this study was to determine the effects of rapid awakening following flumazenil after major abdominal surgery with benzodiazepine-fentanyl TIVA. Six patients (4 male, 2 female) scheduled for elective laparotomies participated in this pilot study. The average duration of surgery was 2.2 +/- 0.9 h. The patients were given 2 mg flunitrazepam p.o. the evening before surgery and 1 h before being brought to the operating room. Baseline pre-induction values were obtained 15 min after inserting catheters and attaching the EEG electrodes. Fentanyl (0.005 mg/kg) was given as a bolus injection followed by a rapid midazolam infusion. The infusion rate was calculated using the method of Wagner et. al. from the data of Lauven et al. to give plasma concentrations of 500 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗