Showing papers in "Anaesthesist in 1987"

Effect of Disoprivan (propofol) on the circulation and oxygen consumption of the brain and CO2 reactivity of brain vessels in the human

Abstract: The effects of Disoprivan on cerebral blood flow (CBF), cerebral oxygen consumption, and CO2-reactivity of the cerebral vessels were studied in 11 male patients between 49 and 63 years of age who were about to undergo coronary artery bypass surgery. Mean perfusion pressure was decreased by 25% under anaesthesia by 0.2 mg/kg per minute Disoprivan, but remained within the ranges of autoregulation. CBF decreased by 51% and cerebral vascular resistance (CVR) increased by 55% following a 36% decrease in cerebral oxygen consumption which was associated with a decrease in neuronal activity in the EEG. Hyperventilation led to a 25% further decrease in CBF due to a 43% increase in CVR while cerebral oxygen consumption remained unchanged. Hypoventilation was followed by a 67% increase in CBF and a 44% decrease in CVR cerebral oxygen consumption was decreased by 38%. This study shows that the reactivity of the cerebral vessels to changes in paCO2 is well maintained under Disoprivan.

The effect of stress ulcer prevention on the incidence of pneumonia in artificial respiration

Abstract: The role of stress ulcer prophylaxis in increasing the risk of pneumonia in ventilator patients was analyzed prospectively in 142 artificially ventilated patients at a medical and surgical intensive care unit (104 males, 38 females, mean time of ventilation 7.9 days, mean age 46.5 years). The pH of gastric aspirate and bacterial counts in gastric fluid and tracheal secretions were investigated daily. Identical isolates from gastric aspirates and tracheal secretions were typed by agglutination, bacteriocin, or phage typing. An average of 2.1 bacterial species were isolated in 80.5% of all gastric aspirates. Bacterial counts increased with rising gastric aspirate pH, which was especially true for Gram-negative and less so for Gram-positive organisms; colony counts of Candida sp. decreased slightly. In 31.6% of patients identical bacterial species were first isolated from gastric aspirates and 1 to 2 days later from tracheal secretions. Of these microbes that were first isolated from gastric aspirate and later from tracheal secretions, 50.3% were Gram-negative, 37.5% Gram-positive, and only 4.2% Candida sp. One-half of all bacterial aspirations occurred between the 2nd and 7th day of ventilation; 80% occurred within 11 days of ventilation. Only 20% of all migrations of Gram-positive organisms from stomach to respiratory tract lead to pneumonia, as compared with 60% of Gram-negatives. At a gastric pH below 3.4 the incidence of ventilation pneumonia was 40.6%; above pH 5.0 the incidence was 69.2% (P less than or equal to 0.05). As pH increased, the organism causing pneumonia was significantly more often isolated first from the gastric aspirate and 1 to 2 days later from the tracheal secretion of the same patient.

Intravenous anesthetics and human neutrophil granulocyte motility in vitro

Abstract: Polymorphonuclear leukocytes (PMN) form a major part of the body's nonspecific first line of defense. An early event, prerequisite for the effective restriction of microbial invasions, is the chemotactic movement of activated neutrophils towards the invading organisms. To date, only limited and contradictory data exist regarding the effects of various intravenous anesthetic agents on neutrophil migration. In this study, the influence of ketamine, etomidate, midazolam, diazepam, and six commonly used i.v. barbiturates (hexo-, pheno-, pentobarbital, methohexital, thiopental, thiobutobarbital) on the in vitro motility of isolated human PMN was tested. Purified PMN (greater than 95%) were obtained from venous blood samples of healthy adults by dextran sedimentation, subsequent ammonium chloride treatment for red blood cell lysis, and Ficoll-Hypaque gradient centrifugation. Random and chemotactic migration were assessed under 1% agarose in the presence of 10(-3)-10(-7) M logarithmic dilutions of the agents in antibiotic free migration medium (MEM). N-fMet-Leu-Phe (FMLP) served as the standardized chemical attractant (10(-7) M). PMN motility was unaffected by ketamine and etomidate, but a significant (P less than 0.001), dose - related depression could be observed with both benzodiazepines at concentrations exceeding 10(-5) M (Fig. 1). Except at 10(-3) M concentration, this migratory inhibition proved to be easily reversible (Fig. 3). At the highest concentration tested (10(-3) M), all the barbiturates caused a significant (P less than 0.001) but completely reversible depression of random as well as chemotactic PMN migration (Table 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Status of postoperative pain therapy in West Germany. Results of a representative survey

Abstract: To determine how pain is assessed and managed in the early postoperative period, what the prescribing habits and general opinions on postoperative pain are, and what suggestions for future improvement could be made, questionnaires were sent to 430 anesthesia departments in the FRG. Of these, 188 were returned (38% response). Systemic treatment (opiates, major and minor tranquilizers, peripherally acting analgesics and spasmolytics) was preferred in most cases, although regional anesthesia/analgesia seems to be rather popular. Data are given not only for analgesic techniques, but also for the most frequently used drugs. The study highlighted deficiencies in communication between the anesthetic staff and the patients that resulted in poor assessment of acute pain problems. The findings indicate a need to document pain and pain relief more often and more precisely in order to improve postoperative pain control.

Continuous Midazolam infusion for sedation of respirator patients

Abstract: UNLABELLED Most intensive care (ICU) patients need pharmacological sedation during ventilatory support. The short-acting drug midazolam might be preferable to neuroleptic agents and opiates because of its anxiolytic and sedative properties. The dosage of a drug given in a continuous infusion is based upon knowledge of its clearance and of the function of concentration and effect. METHOD A midazolam infusion (7.5 or 15 mg/h) was given to 16 patients receiving ventilatory support for 24 h. Clearance was estimated using the rule Cl = R/C (R = rate of infusion, C = concentration in steady state). To estimate the concentration of midazolam necessary for good sedation, the amount of supplementary injected neuroleptic during midazolam infusion was compared with that of the day before. Plasma cortisol and parameters of energy metabolism, electrolytes, and liver and kidney function were measured. RESULTS Patients with disease of abdominal organs showed the lowest values for clearance (1.0-2.92 ml/min/kg). Some of the injured patients showed elevated values for clearance (3.0-21.36 ml/min/kg). Elimination half-life ranged from 1.5-50 h. Changes in intestinal perfusion or cardiac output might be responsible for the wide range. For good sedation, plasma midazolam concentrations had to be above 600 ng/ml. Plasma cortisol levels were not affected by midazolam, nor were metabolism, electrolytes, or liver and kidney function. CONCLUSION Continuous infusion of midazolam is a useful way of sedation for ICU patients, but the wide range of clearance values must be considered.

Effects of intubation anesthesia on the temporomandibular joint

Abstract: Hardly any attention has so far been paid to temporomandibular joint (TMJ) dysfunction after endotracheal intubation. We examined perioperative lesions of the TMJ in 100 patients who underwent operations in areas other than the head and neck. Fifty of these patients were anesthetized with orotracheal intubation; the other 50 were operated under spinal or peridural anesthesia. The orotracheal intubations were carried out with Macintosh laryngoscopes (blatesize 3). Size 32 Kuhn tubes or Magill tubes were used in 25 patients each. Preoperatively and daily for the first 4 postoperative days, we repeated the history and examined the minimal distance between the occlusal edges of upper and lower incisors (SKD), deviations of the mandible during opening and closing movements, and snapping or grinding of the TMJ. We further measured the duration of intubation, technical difficulties, and the number of years of training of the anesthetist. Age, body length, and preoperative findings were compatible in both patient groups. Operating time was 25% longer in the spinal or peridural anesthesia group. Of the 50 patients with orotracheal intubation, 33 demonstrated a reduced ability of maximal oral opening of up to 35% on the 1st postoperative day. Snapping of the TMJ was observed in 80% of the orotracheally intubated patients on the 1st postoperative day, which was 20% above the preoperative value. TMJ grinding showed no significant changes. Two of the 50 intubated patients complained of TMJ pain, another two had occlusal disturbances, and two had a reduced SKD. There were no detectable differences within the group of intubated patients regarding type of tube or experience of the anesthetist.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous analgesia with ketamine for emergency patients

Abstract: Twenty traumatized patients suffering from fractures and soft tissue injury were given either 0.25 mg/kg or 0.5 mg/kg ketamine intravenously for analgesia. Within 5 min effective analgesia was present in both groups and lasted for 10-15 min. The higher dose of ketamine led to an impairment in the level of consciousness. These findings were in agreement with plasma levels of ketamine: in the 0.25 mg/kg group the plasma levels (median) were 167 ng/ml after 5 min, 92 ng/ml after 10 min, 82,5 ng/ml after 15 min, and 46 ng/ml after 30 min (n = 4). In the 0.5 mg/kg group the plasma levels (median) were 238 ng/ml after 5 min, 189 ng/ml after 10 min, 135 ng/ml after 15 min, and 118 ng/ml after 30 min. Considering the influence on consciousness, we recommend the administration of 0.25 mg/kg ketamine intravenously for analgesia in traumatized patients without head injury. It may be necessary to repeat the same dose if pain re appears.

Intracranial pressure in patients with craniocerebral trauma after administration of propofol and thiopental

Abstract: Propofol (Disoprivan) is a rapid and effective hypnotic comparable with etomidate. Up to now, the effects on intracranial pressure (ICP) have only rarely been investigated, especially in cases with pre-existing increased ICP [4, 18]. The aim of this study was the evaluation of ICP after i.v. propofol administration in comparison with thiopental. Method. Five patients were studied, all of whom had had isolated head trauma. All were on controlled ventilation and were unconscious. Depending on the result of computer tomography, an epidural pressure transducer was implanted. ICP, blood pressure (BP), and heart rate (HR) were measured before and 1, 3, 5, 10, and 15 min after 1 mg/kg propofol; subsequently 2 mg/kg thiopental were administered and the same parameters documented. Cerebral perfusion pressure (CPP) and mean arterial pressure (MAP) were calculated. Results. ICP decreased in all five cases 5 min after the initial values were measured. Two patients showed an ICP decrease after thiopental. BP was reduced markedly by propofol and very slightly by thiopental. The CPP showed a small decrease in four patients after propofol and in two after thiopental. Conclusions. The data now available permit the conclusion that both propofol and thiopental can be used in patients with possibly elevated ICP. The marked cardiovascular side effects of propofol must be taken into consideration.

Anaphylactic shock during excision of an intraosseous Echinococcus granulosus cyst

Abstract: During the excision of a cystic tumor of the left proximal thigh under general anesthesia a severe anaphylactic shock was observed in a patient. This severe allergic reaction was due to the puncture of an Echinococcus granulosus hydatid during the preparation of a bone-plate covering the bony cyst of the left thigh.

Heart dislocation following extensive lung resection with partial pericardial resection

Abstract: Cardiac herniation is a rare but dramatic complication of pulmonary resection that demands urgent treatment. About 50 patients have been reported in the literature; 50% of them died. Symptoms vary depending on the location of the pericardial defect. Cardiac output falls, central venous pressure rises, and cyanosis develops that does not respond to oxygen administration. Right-sided herniation is characterized primarily by decreased blood pressure and tachycardia due to kinking or torsion of both superior and inferior venae cavae and subsequent reduction of cardiac filling. Left-sided herniation more often produces ischemic ECG changes and dysrhythmias due to jamming of the ventricles between the edges of the pericardial defect. Without intervention irreversible myocardial damage may rapidly result. Luxation typically arises at the end of the operation or in the early postoperative period. Precipitating factors are suction on the chest tube, changes in the patient's positioning, positive pressure ventilation to expand the remaining lung segments, coughing and extubation. In right-sided luxation an anteroposterior chest X-ray will substantiate the diagnosis without difficulty; in left-sided luxation the chest film may not show a similarly striking finding. Often dramatic deterioration in the patient's status may not allow time for diagnostic procedures. In case of doubt, immediate rethoracotomy is indicated. In the case observed, a 47-year-old woman underwent right pleuropneumonectomy with partial pericardectomy and intrapericardial ligation of the pulmonary vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

[Endocrine stress response in halothane, enflurane and isoflurane anesthesia in surgical interventions].

Abstract: The endocrine stress response under inhalation anesthesia with halothane, enflurane, and isoflurane was investigated in 30 patients during and after orthopedic surgery (Table 2). Plasma levels of adrenaline and noradrenaline (by HPLC/ECD), ADH, ACTH, and cortisol (by RIA), glucose, lactate, and free glycerol were determined before induction of anesthesia, 10 min after intubation, 10 min before the end of the operation, and 5 and 30 min after extubation. Statistical evaluation was undertaken by analysis of variance with repeated measures on one factor. P values of less than 0.05 were considered significant. There were no significant differences in the concentrations of plasma catecholamines (Table 4, Figs. 1 and 2), ADH, ACTH (Table 5, Figs. 3 and 4), or cortisol before and during surgery between the groups. ADH was lower in the halothane group 5 and 30 min after extubation (P = 0.05), which might be due to the prolonged elimination of halothane after anesthesia. Blood pressure, heart rate (Table 3), and plasma concentrations of glucose, lactate, and free glycerol (Table 6) were comparable in all groups. It is concluded that for clinical practice halothane, enflurane, and isoflurane are comparable in their influence on the surgical stress response.

[O.15 mg Intrathecal buprenorphine applied for postoperative analgesia. A clinical double-blind study].

Abstract: In a double-blind, randomized study of 29 patients who underwent orthopedic procedures we studied the additional effect of intrathecal buprenorphine on isobaricpinal anesthesia and postoperative analgesia. The injections were 20 mg tetracaine (19 patients) or 20 mg tetracaine plus 0.15 mg buprenorphine (10 patients). In both groups the drugs were contained within a total volume of 4 ml cerebrospinal fluid. Progression and regression of the sensory blockade of spinal anesthesia were estimated with pinprick; the motor blockade was judged by the Bromage scheme. Postoperative pain was evaluated by the patients using an analogue scale after Scott and Huskisson. Arterial blood gases, respiratory rate, blood pressure, and heart rate were measured and other side-effects determined. Both groups were comparable in age, body weight, height and duration of operation (Table 1). The addition of buprenorphine elevated the sensory blockade by three segments both during spread and regression of anesthesia (Figs. 1, 2). Postoperative analgesia was better up to 8 h after injection (p less than 0.05), after 8 h pain levels were equal in test and control groups (Fig. 3). After buprenorphine patients became aware of pain sensation 13 h after injection; in the control group the pain-free interval lasted only 9 h (p greater than 0.05). There were no differences in the need for postoperative analgesics between both groups. The respiratory rate was lower during the whole period of observation (p less than 0.05). The mean values for PaCO2, pH and BE were similar in both groups (Fig. 4). PaO2 was elevated in the buprenorphine group. There was no essential alteration of blood pressure after buprenorphine. The pulse rate, however, was slightly diminished.(ABSTRACT TRUNCATED AT 250 WORDS)

Midazolam (Dormicum) as oral premedication for local anesthesia

Abstract: Good physician-patient rapport and an anxiolytic, sedative, and amnesic premedication are necessary for comfortable, stress-free surgery under local anesthesia. Sufficient experience exists with the intramuscular and intravenous administration of the new benzodiazepine midazolam (Dormicum), while knowledge relating to its oral administration is still scant. Therefore, in a randomized double-blind study midazolam was investigated for oral premedication prior to local anesthesia: two dosages of midazolam were studied and compared with diazepam and placebo. One hour prior to ophthalmic surgery under local anesthesia, four randomized groups of 30 patients each, received a tablet of 7.5 or 15 mg midazolam, 10 mg diazepam, or a placebo. Following this medication, the anxiolytic, sedative, amnesic, and side-effects were determined at defined points of time during the day of surgery and the 1st postoperative day. Anxiolysis was determined using the "state-trait anxiety inventory (STAI)" of Spielberger et al.; sedation was assessed according to Pandit et al.; amnesia was determined by recall of picture cards which had been presented to the patients 50 min after premedication; and patients were asked about 13 side-effects typical of benzodiazepines in a standardized way. Anxiety increased little following the placebo; it decreased significantly following 10 mg diazepam and more markedly following 7.5 and 15 mg midazolam. Sedation increased little following the placebo; it increased more and similarly 50 min after the benzodiazepines; after 90 min the sedative effect was most marked for 15 mg midazolam. However, sedation was of shorter duration after midazolam than after diazepam.(ABSTRACT TRUNCATED AT 250 WORDS)

Modification of intracranial pressure by propofol (Disoprivan). Initial results

Abstract: The effects of propofol on intracranial pressure (ICP) were studied in seven patients with isolated intracerebral injuries. All patients had lost consciousness and were intubated and ventilated. On the basis of computed tomography (CT) of the brain, it was decided whether an implantation for epidural pressure monitoring was indicated. Implantation of the pressure transducer was followed by measurements of epidural pressure, blood pressure, heart rate, and blood gas analysis. Propofol 1 mg/kg body weight was administered and all parameters measured again 1, 3, 5, 10, and 15 min after dosing. The CT showed contusion bleeding and narrowed complemental space in all patients. The individual intracranial pressure profiles are shown in Fig. 1. Except for one patient who showed an extremely unstable and excessively high ICP even during subsequent thiopental treatment, no increase was observed after propofol. The cerebral perfusion pressure showed no relevant changes, nor did blood pressure or heart rate. It can be concluded from this study that propofol (ICI-Pharma) causes no ICP increase in patients with elevated ICP and may be used in these cases as an induction hypnotic.

Experience with extracorporeal CO2 elimination

Abstract: The method of extracorporeal CO2-elimination (ECCO2-R) as described by L. Gattinoni [2] and Kolobow [5] is reported in ten patients with severe ARDS in whom conventional respirator therapy had failed. The method itself as well as important pulmonary function parameters, e.g. changes in gas exchange (Fig. 3), extravascular lung fluid (Fig. 6), and chest radiographs are explained. After 7-17 day treatment with the Life-Support System (LSS), seven patients were in satisfactory condition to allowing weaning from the ventilator (Responder). In three cases the lung mechanics and gas exchange were unchanged by the therapy with CO2 removal and high PEEP (Nonresponders). In the responders, oxygenation improved and the intrapulmonary shunt Qs/Qt (Fig. 4) decreased, followed by extravascular lung water and mean pulmonary arterial pressure (Fig. 5). Towards the end of the therapy we could find normalization of the compliance (Fig. 7) and chest X-rays, which may be interpreted as a cure. The results confirm our theory that ECCO2-R in combination with high PEEP and low-frequency ventilation seems to be an important method for future therapy of acute pulmonary failure.

[Comparative hemodynamic study of anesthesia induction with propofol (Diprivan), thiopental, methohexital, etomidate and midazolam in patients with coronary disease].

Abstract: UNLABELLED In patients undergoing cardiac surgery, the induction of anesthesia is not without risk because of specific cardiovascular effects of the anesthetic and the preoperative state of the patient. The hemodynamic effects of etomidate, midazolam, thiopental, and methohexital are well known: etomidate is an anesthetic that induces only minor cardiovascular changes; its influence on the endocrine system, however, has reduced its clinical indication. Barbiturates such as thiopental and methohexital produce negative inotropic effects in combination with an increase in heart rate and myocardial oxygen consumption; midazolam reduces pre- and afterload in patients with poor left ventricular function. Propofol, a new short-acting induction agent with good anesthetic properties, is said to diminish arterial pressure as well as myocardial oxygen consumption. METHODS In a randomized study we investigated the hemodynamic effects of intravenous induction with propofol (2 mg/kg body wt.), thiopental (5 mg/kg), methohexital (1 mg/kg), etomidate (0.3 mg/kg), and midazolam (0.15 mg/kg) in 50 patients undergoing coronary artery bypass grafting. All patients were premedicated with flunitrazepam (0.03 mg/kg up to 2 mg) and morphine hydrochloride (0.2 mg/kg up to 15 mg) 100 min before the investigation. After 0.003 mg/kg fentanyl the patients received the induction agent in the above-mentioned dosage within 40 s followed by 0.1 mg/kg pancuronium bromide. Hemodynamic measurements were performed 1, 3, and 5 min after the end of the injection as well as 1 and 5 min after intubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Complement activation following head and brain trauma

Abstract: The prognosis for a patient with a severe head injury is dependent not only upon the location and the degree of this trauma, but also upon additional complications. For example, disseminated intravascular coagulation (DIC) can occur because of the thromboplastic activity of the damaged brain tissue that enters the circulation. The complement (C) system is activated by certain enzymes that cleave the clotting factors. Therefore, after head injuries we searched for C activation because it could result in the adult respiratory distress syndrome (ARDS). Patients and methods. We had two groups of patients: (1) 23 with large destruction and (2) 13 with little destruction of the brain tissue. Eighteen patients in group 1 and 8 in group 2 had isolated brain trauma. Blood samples were taken--upon arrival at the hospital and then 1, 3, 7, 12, 24, and 48 h later; after that we took weekly blood samples up to the completion of their treatment in the intensive care unit. We measured the total hemolytic serum C activity (CH50), activation of alternative pathway hemolysis (APH50), cleavage products C3a and C3d, and total protein. Furthermore, we studied the coagulation parameters of the extrinsic (prothrombin time) and intrinsic (partial thromboplastin time) pathways and fibrinogen content. From the patients records we extracted clinical parameters such as neurological status, intracranial pressure, pathological details on computer tomography hemoglobin and arterial-alveolar oxygen difference. Results. Figure 1 shows the different reactions of the C system in both groups: while patients of group 1 suffered from a decrease in total and alternative hemolytic activity, the other group increases in both parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of anesthesia in elderly patients

Abstract: Progress in surgery and anesthesia has contributed to lowering operative risk and expanding the indications for operations in higher age groups. The goal of treatment in the elderly is to achieve the best possible degree of reducing discomfort and increasing personal independence. Methods. A brochure with a clinical study on 1,021 patients chosen at random shows the frequency of complications arising during the peri- and post-operative course in patients around 60 years of age and older. Operative areas were general and emergency surgery, vascular surgery, neurosurgery, and urology. Operations were carried out in regional or general anesthesia. Patients were divided into groups below and above age 60. Evaluation of the data was carried out according to an integrated data processing concept. This program enables quantitative and qualitative data to be combined at will, taking into consideration that evaluating criteria can be varied considerably. Results. The results demonstrate that patients over 60 have significantly more complications than patients under 60. Analysis of the influence of the factors associated with surgical risk reveals that factors related to the operation such as type, length, and extent do not increase the risk as much as the numerous accompanying illnesses in both age groups. As far more elderly patients are affected by multimorbidity, the conclusion may be drawn that the increased risk observed is not due mainly to age, but rather to the patient's condition prior to surgery. The results indicate clearly that an exact analysis of the initial condition as well as avoiding failure or malfunction of certain organs must have priority in both age groups.

Therapy of paradoxical reactions to midazolam in regional anesthesia

Abstract: Many patients fear being awake in the operating room, and the acceptance of regional anesthesia is often made dependent on the promise of adequate sedation. With the introduction of the short-acting benzodiazepine (bzdp) midazolam, it seemed possible to achieve induction and maintainance of sleep throughout an operative procedure. This substance may, however, occasionally result in a "paradoxical reaction" (PR) characterized by agitated excitement, mental confusion, and uncooperativeness. We have treated this condition successfully with physostigmine, as documented here in two case reports where a possible interaction between promethazine and midazolam may have been responsible for the PR. The symptoms resemble some of those seen in the central anticholinergic syndrome, as further implied by the therapeutic effect of physostigmine, but an etiological difference may exist. A direct anticholinergic effect of bzdp's is described only following excessive doses. An indirect effect may result from the impact on GABA-receptors, which have been identified as structurally related to the bzdp receptors. Physostigmine itself is not bound at the bzdp receptor, but has been shown to block the binding of bzdp's to their receptors and to reverse sedation from midazolam, perhaps through an indirect stimulatory effect. Previous case reports have indicated the effect of physostigmine in reversing PR following various bzdp's. Without treatment, a PR during regional anesthesia frequently makes general anesthesia necessary in order to immobilize the patient sufficiently to make surgery possible.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of fentanyl and enflurane on sensory evoked potentials in the human in basic flunitrazepam/N2O anesthesia].

Abstract: The use of evoked potential recording is commonly employed for monitoring peripheral and central sensory functions during neurosurgical procedures. However, the neuronal structures studied must not be changed by the anesthetic agents used. In this connection, the influence of two anesthetics, fentanyl and enflurane, on evoked potentials was investigated under basic anesthesia. A total of 60 patients undergoing lumbar disc removal were included in the study. Somatosensory (SEP), auditory (AEP), and visual (VEP) evoked potentials were each recorded in 20 patients the day before operation. Basic anesthesia was induced with flunitrazepam, nitrous oxide, and pancuronium bromide. Following induction, recordings of evoked potentials were again made. One half of each group of 20 patients received increasing doses of fentanyl (1.8, 3.6, and 7.2 micrograms/kg in the somatosensory and auditory groups; 4.0 and 8.0 micrograms/kg in the visual group). The other half was given increasing inspiratory concentrations of enflurane (0.5, 1.0, and 1.5 vol.%). At each level of anesthesia, SEPs, AEPs or VEPs were recorded. As compared with preoperative recordings, post-stimulus latencies were virtually unaffected by the basic anesthesia. Fentanyl caused little increase in the latencies of middle-latency-SEPs and of peak P2 of the VEPs. With enflurane, however, the latencies of the SEPs were dose-dependently prolonged, in particular those of the later components (P25 to N55). The same was true for the peak P2 in the VEPs. AEPs were not changed at all. From the results it can be concluded that enflurane, but not fentanyl, impairs impulse conduction in central synaptic pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

[Affinity of oxygen for hemoglobin--its significance under physiological and pathological conditions].

Abstract: Hemoglobin as a vehicle for oxygen carries roughly 65 times the volume of oxygen that would otherwise be transported by simple solution in plasma. Conformational shifts of the molecule induce a cooperative oxygen-hemoglobin affinity. This property is reflected in the sigmoidal shape of the oxygen-hemoglobin dissociation curve. The affinity of hemoglobin is affected by temperature, hydrogen ions, carbon dioxide, and intraerythrocytic 2,3-DPG, with all these factors mutually influencing each other. Physiologic conditions associated with shifts in hemoglobin-oxygen affinity are oxygen uptake in the lung, oxygen delivery in the capillaries, and particularly oxygen delivery in working muscle, diaplacental oxygen transfer, and the regulation of erythropoesis. Hemoglobin-oxygen affinity attains pathological significance for oxygen supply during respiratory or metabolic alkalosis when the hemodynamic and tissue responses of the individual are limited: the increased affinity can critically lower capillary oxygen tension. Methemoglobin and carbon monoxide shift the oxygen dissociation curve to the left, so that intoxication with both substances reduces both total oxygen capacity and oxygen delivery of the remaining hemoglobin able to bind oxygen. This effect of methemoglobin and carbon monoxide must be considered in intensive care of intoxicated victims. Transfusions of large volumes of stored red cells, whose hemoglobin shows high affinity, can force the capillary oxygen tension down, especially in patients with impaired cardiac performance. The lowered oxygen affinity of patients with chronic renal disease and anemia must be preserved by avoiding an increase in the acidotic plasma pH. In the neonate, hemoglobin possesses a high affinity for oxygen physiologically; the hemodynamic reserve of the neonate is limited. Therefore, the hemoglobin content plays a crucial role in oxygen transport capacity during the initial months of extrauterine life. Consequently, red cell transfusion must be started much earlier in neonatal surgery than in adults. The red cells must be fresh, or at best "rejuvenated". Normally, oxygen affinity is not relevant for oxygen supply, but the position of the oxygen-hemoglobin dissociation curve may be a critical factor in the situations described above, particularly when blood flow is additionally restricted.

[Pathophysiologic principles, emergency medical aspects and anesthesiologic measures in severe brain trauma].

Abstract: In 60%-90% of cases head injury is a part of multisystem trauma and of very decisive importance for the post-traumatic prognosis. Hypoxia, hypercarbia, and hypotension increase the primary lesion and cause secondary brain damage. Therefore, emergency measures must be directed to the essentials of sustaining vital functions, i.e. intubation/ventilation/oxygenation and stabilization of the circulatory system. All trauma-specific measures should avoid additional increases in intracranial pressure or should decrease it if already elevated. Moderate hyperventilation not only causes cerebral vasoconstriction with a concomitant decrease in intracranial blood volume and intracranial pressure, but also partly restores the disturbed cerebral autoregulation, and is therefore an important part of the emergency care and anesthetic procedure in patients with severe head injuries. It is supplemented by analgesia and sedation to prevent intracranial pressure increases due to painful external stimuli. Elevation of the head and upper part of the body by 30 degrees causes a decrease in intracranial pressure by decreasing intracranial blood volume due to improved venous return from the brain; however, this measure is to be applied only in stable circulatory conditions. The head should be put in mid-position avoiding sideways rotation, flexion, and hyperextension. Osmotically active agents are only indicated in emergency situations when there are signs of clinical deterioration. High-dose barbiturate therapy is reserved as a "last resort", under intensive care conditions, for controlling an otherwise intractable intracranial pressure rise. Calcium antagonists have no indication in this context. Anesthesia in patients with severe head injury must involve only those techniques that do not further increase an already elevated intracranial pressure. As inhalational anesthetics, including nitrous oxide, elevate the intracranial pressure to varying extents due to cerebral vasodilation with a concomitant rise in intracranial blood volume, these substances have to be avoided whenever raised intracranial pressure cannot be excluded. Narcotics, benzodiazepines, small dosages of barbiturates, and long-lasting muscle relaxants can be regarded as useful.

Current status of treatment of the cerebral edema

Abstract: The treatment of cerebral edema has changed during recent years. On the one hand, knowledge of the pathophysiology of brain swelling has expanded; on the other, the analysis of biodata such as intracranial pressure, cerebral blood flow, and blood volume has become routine. The methods of measuring intracranial pressure (nowadays without risk due to the use of microtipepidural probes, e.g. Gaeltec) in particular, make it possible to monitor the effects of therapy and enable us to evaluate the different therapeutic measures individually for each patient. Regarding drug treatment, osmotherapy deserves first mention, especially the polyvalent alcohols mannitol and sorbitol, but in spite of possible side effects, glycerin as well. Knowledge of the mechanism of osmotic therapy leads to the proper concept of treatment with bolus administration under control of serum osmolarity and intracranial pressure. Corticosteroids only effectively influence the cerebral edema caused by tumor. The treatment of posttraumatic (and postoperative) cerebral edema is described controversally in the literature. As the side-effects of cortisone therapy are under control, corticosteroids may also be included in the treatment of therapy-resistant cerebral edema. Acting together with sedative drugs, procaine derivatives help to reduce intracranial pressure peaks during intensive care measures. Barbiturates are used as sedatives or in a loading dose until burst suppression is seen in the EEG. The risk of hemodynamic side effects such as reduced cardiac output and cerebral perfusion pressure is decreased by measuring pulmonary arterial pressure and the use of catecholamines. The acidotic impairment of cerebral autoregulation can be regulated using THAM (thrometamine) and the response of the vascular system to hypocapnia can be improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Success rate and complications of a modified retrograde intubation technic in 36 patients

Abstract: The main disadvantage of guided blind intubation (Waters technique) is injury to the mucous membrane and cartilaginous skeleton of the larynx. Thirty-six patients scheduled for laryngectomy were intubated using a modified Waters technique. The practicability of this technique as well as the type and extent of damage to the laryngeal tissue were evaluated under controlled conditions. Intubation was successful in 35 patients (first attempt, 31 patients; 2-3 attempts, four patients). A stenosing carcinoma of the larynx required a tracheotomy in the remaining patient. No serious damage to the mucous membrane or cartilage was demonstrated in the 26 controlled resected larynges. In a difficult intubation, the guided blind technique is a possible alternative because of the relatively low extent of damage and technical requirements; maintenance of spontaneous respiration is not required.

[Acoustically evoked brain stem potentials. Prerequisites for clinical use, data quality and sources of error].

Abstract: Ninety patients were subjected to brain-stem auditory evoked potential (BAEP) measurements in the intensive care unit. The data are analyzed and discussed with respect to their quality, reliability, and reproducibility. BAEPs of a quality satisfactory for diagnosis were found in 90% of the patients. About 10% of the measurements were distorted by artifacts and could not be used for diagnostic purposes. Reasons for these artifacts and problems of interpretation are discussed. Examples of single BAEPs and on-line monitoring of BAEPs in the form of "compressed BAEPs" are shown.

Behavior of the histamine level in induction of anesthesia with propofol and methohexital

Abstract: In a study of the effect of intravenous anesthetics on plasma histamine levels, propofol and methohexital were administered to patients. Histamine determination was performed using an improved fluometric method specific for imidazole derivatives. As a primary step, the plasma histamine concentration was determined in 60 healthy, fasting probands and used as a comparative value. The mean value obtained from 60 examinations was 0.38 +/- 0.12 ng/ml, the median value was 0.37 ng/ml (Table 1). The next step consisted in determination of plasma histamine values in 20 patients 1 h following premedication with fentanyl. In this group, the mean value was 0.33 +/- 0.11 ng/ml, the median value 0.316 ng/ml (Table 2). In another 20 patients the plasma histamine concentration was determined 1 h following intramuscular injection of 1.4 microgram fentanyl +0.07 mg/kg droperidol (Thalamonal). In this group, the mean value was 0.373 +/- 0.11 ng/ml and the median value was 0.736 ng/ml. Subsequently, the effect of 2.5 mg/kg propofol (Disoprivan) or 1 mg/kg methohexital (Brevimytal) on plasma histamine levels was examined in a randomized, prospective study in 22 patients of ASA class I and II (Table 3, Fig. 2). Two minutes prior to injection of the test substances and 2, 4, 8, and 13 min following injection, plasma histamine levels, blood pressure, and heart rate were examined. In both groups, no changes in plasma histamine levels were observed during the period of examination. Comparison of the individual time columns within a group as well as intergroup comparisons revealed no statistically significant differences in either the t test or the Wilcoxon-Mann-Whitney U test.(ABSTRACT TRUNCATED AT 250 WORDS)

[Non-invasive Doppler-ultrasound determination of cardiac output. Results and experiences with the ACCUCOM].

Abstract: Because of the invasiveness of the method, the determination of cardiac output (CO) by the thermodilution technique is not without a certain risk to the patient. Previous studies have suggested that noninvasive Doppler technology could be used to determine the velocity of blood in the aorta. With knowledge of the diameter of the aorta, CO can be calculated. The newly developed ACCUCOM (Datascope Corp.) measures CO noninvasively by Doppler ultrasound. However, there is not much information as to how the ACCUCOM performs in clinical practice. The present study was designed to compare the determination of CO by the ACCUCOM with that by thermodilution. CO was determined simultaneously in 12 anesthetized patients scheduled for abdominal or orthopedic surgery. There was a significant but not very tight linear correlation (r = 0.82) between ACCUCOM and reference measurements. The ACCUCOM underestimated CO on the average by 32%. In order to analyze the ACCUCOM tracking of relative changes in CO, in 6 out of 12 patients CO was also determined during cardiac stimulation by isoprenaline (0.5-1.0 microgram.min-1) IV. The resulting increase in CO was detected reliably using the ACCUCOM. It was, however, significantly overestimated by the Doppler technique (average increase = 58%) as compared to the reference method (average increase = 42%). These results suggest the possibility of major deviations in determining CO with the ACCUCOM.(ABSTRACT TRUNCATED AT 250 WORDS)

Calculation of the allowable blood loss before transfusion with a programmable pocket calculator

Abstract: Introduction The amount of blood loss during surgery that requires transfusion is frequently estimated with a linear formula (1) using blood volume--calculated on a volume per weight basis--, preoperative hemoglobin concentration, and an established minimum hemoglobin concentration This formula, however, underestimates allowable pretransfusion blood loss, because it implies that all blood lost contains the initial hemoglobin concentration In addition, hemodilution by infusion therapy prior to surgery is usually not taken into consideration Methods In order to estimate allowable pretransfusion blood loss more accurately and conveniently, a program was developed for a programmable pocket computer This program calculates (number of equation in parenthesis): blood volume (2a, 2b) expansion of blood volume prior to surgery (3) hemodilution prior to surgery (4) allowable blood loss during isovolemic hemodilution (5) The applicability of the program to the situation during orthopedic operations was tested in a study in which allowable pretransfusion blood loss was estimated for one group of patients and was calculated with the computer program for another group of patients Eighty patients undergoing major orthopedic surgery were studied After preoperative evaluation the attending anesthetist established a minimum hemoglobin concentration and the type of cardiocirculatory monitoring to be used Patients were divided at random into two groups: for one group blood volume was estimated on a volume per weight basis and allowable blood loss was calculated using equation (1); for the second group allowable blood loss was calculated with the computer program During the evaluation of the data the computer calculations were also carrier out for group 1(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic action profile of propofol in comparison with midazolam. A study in coronary surgical patients

Abstract: Propofol, a rapid and short-acting i.v. anesthetic, was associated with the risk of anaphylactic reactions in its original cremophor-EL formulation. It has been reformulated in a soybean emulsion with satisfactory anesthetic properties. A former study of hemodynamic changes after i.v. induction with propofol, thiopental, methohexital, etomidate, and midazolam in patients with coronary artery disease demonstrated that in comparison to other induction agents propofol depressed systolic and diastolic arterial pressures more severely, compromising coronary perfusion. In the present investigation left ventricular parameters as well as hemodynamic effects during extracorporeal circulation (ECC) were studied in comparison to midazolam during opiate analgesia. Methods. Hemodynamic effects of 2 mg/kg body weight propofol as compared to 0.15 mg/kg midazolam were studied in 34 patients during coronary artery surgery before cannulation of the large vessels (measurement of left ventricular parameters) or during ECC (measurement of arterial perfusion pressure and oxygenator volume). Results (see Table 1, Figs. 1 and 2). Propofol decreased systolic and diastolic pressures (-27%, -22%) more than midazolam (-10%, -9%). Cardiac index and stroke volume index were diminished following both drugs (propofol: -14%, -9%; midazolam: -15%, -11%); total systemic resistance was reduced significantly by propofol (-22%). Dp/dtmax was compromised more markedly by propofol (-24%) than by midazolam (-18%), but there was no significant difference.(ABSTRACT TRUNCATED AT 250 WORDS)