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Biomedical subjects

D Knüttgen

Publications and source records attributed to D Knüttgen.

At least 19 recordsLinked to original sources
PubMed1999

Atracurium during thoracic surgery: impaired efficiency in septic processes.

OBJECTIVE: The aim of the study was to examine whether the neuromuscular blocking potency of atracurium changes in patients with a septic intrathoracic process. DESIGN: Prospective clinical study. SETTING: Community hospital. PARTICIPANTS: Thirty patients who underwent thoracic surgery for resection of a pulmonary carcinoma were examined. Fifteen patients showed typical signs of a concomitant bacterial superinfection (infection group), 15 age-matched patients without infection served as the control (no-infection) group. INTERVENTIONS: Relaxation was induced with atracurium, 0.6 mg/kg intravenously for intubation, followed by a continuous infusion to maintain a 90% neuromuscular blockade. Relaxometry was performed electromyographically using the Datex Relaxograph by stimulating the ulnar nerve next to the wrist. MEASUREMENTS AND MAIN RESULTS: The onset time was significantly longer (5.3 +/- 2.9 v 3.3 +/- 1.2 minutes; p < 0.05), and the recovery phase (DUR 10%) was significantly shorter (23.5 +/- 8.6 v 36.9 +/- 7.3 minutes; p < 0.001) in the infection group compared with the controls. The infusion rate within the first hour of continuous application was 77.4% higher in the infection group than in the control group (11.0 +/- 2.9 v 6.2 +/- 1.0 microg/kg/min; p < 0.001). CONCLUSION: The study showed that septic intrathoracic processes cause a clear reduction of the neuromuscular blocking potency of atracurium. To guarantee adequate muscle relaxation in such cases, precise neuromuscular monitoring is highly advisable.

Adult↗
PubMed1998

[Reduced neuromuscular blocking potency of atracurium in patients with purulent intrathoracic diseases].

OBJECTIVE: Based on personal observations the neuromuscular blocking potency of atracurium was supposed to be diminished in purulent intrathoracic diseases. This hypothesis was tested in a prospective clinical trial. METHODS: 52 adult patients undergoing general anaesthesia (methohexitone, sufentanil, flunitrazepam, N2O, enflurane) for elective thoracic surgery were investigated. After the intubation dose of 0.6 mg/kg atracurium was applied continuously to maintain a 90% suppression of the evoked compound electromyogram. According to the intraoperatively established diagnosis patients were allocated to three categories: 1) non-malignant tumor as the control group (n = 15), 2) lung cancer (n = 22), 3) purulent intrathoracic process without tumor (n = 15). The groups were compared regarding onset time, DUR 10% and maintenance dose of atracurium. RESULTS: Patients with lung cancer did not differ significantly from the controls regarding efficiency of atracurium. In contrast, patients with a purulent intrathoracic process showed a significantly longer onset time (6.3 +/- 2.5 vs. 2.9 +/- 0.8 min, p < 0.001), and a significantly shorter DUR 10% (23 +/- 6 vs. 36 +/- 10 min, p < 0.001) compared to the control group. Mean infusion rate of atracurium to maintain a 90% suppression of the evoked compound electromyogram was significantly higher in patients with a purulent process compared to the controls (10.5 +/- 3.2 vs. 6.0 +/- 1.2 micrograms/kg.min, p < 0.001). CONCLUSION: Our results support the hypothesis that patients with a purulent intrathoracic disease show a clear reduction in neuromuscular blocking potency of atracurium.

Adult↗
PubMed1998

[Heparin-induced coagulation disturbance from mechanical autotransfusion].

UNLABELLED: Disorders in blood coagulation during the use of autotransfusion have been reported in recent literature. We wondered whether or not heparine, remaining in the prepared sample of retransfusion blood might be responsible for these disturbances. METHODS: Therefore we created a setting in which heparine was added to animal blood in order to imitate clinical situations during the use of the CELL SAVER. RESULTS: According to our results the blood shows no irregular heparine load as long as the machine is used following the operating instructions. But if the volume of rinsing liquid is decreased or the pumpflow is increased, the heparine load is increased enormously (Table 1). CONCLUSIONS: If the CELL SAVER is used with reduced volume of rinsing liquid or higher velocity of the pump, the coagulation status of the patient has to be monitored meticously.

Animals↗
PubMed1997

Computer aided analysis of heart rate variability in brain death.

Forty neurosurgical, artificially ventilated patients were examined. Twenty of them had been diagnosed as brain dead, while twenty non-brain-dead patients served as a control group. From a surface ECG taken over a period of five minutes the mean heart rate and various indices of heart rate variability (HRV) were determined with the help of a special computer program (ProSciCard, Medisyt, Germany). The heart rate of the brain dead was significantly higher than that of the control patients. By contrast, all parameters of HRV were drastically reduced in the brain dead individuals compared to the controls. The results show that a significant change in the course of heart rate occurs after manifestation of brain death. This would appear to be the result of the elimination of all vegetative impulses derived from the brainstem. Computer-aided, the changes can be quantified in a simple way. The method could therefore be useful in brain death diagnosis.

Adult↗
PubMed1997

[Postoperative resistance against atracurium].

Supported by two case reports we show that resistance to atracurium can develop postoperatively. Both patients had septic complications after elective thoracic surgery. A 39-year-old patient developed a bronchial fistula and a superinfection of the remaining thoracic cavity after pneumonectomy. At the time of rethoracotomy the neuromuscular blocking potency of atracurium had changed drastically: onset time was lengthened (7 vs. 3.5 min), recovery period (DUR 10%) was reduced (14 vs. 28 min) and the maintenance dose had to be tripled (14.3 vs. 5.0 micrograms/kg per minute). Following superior lobe resection in a 56-year-old patient, middle lobe gangrene occurred which had to be removed. In contrast to the first anaesthesia the intubation dose of atracurium had to be increased significantly (70 vs. 40 mg), and even with this amount the neuromuscular blocking effect was not complete. Furthermore to accomplish a convenient state of relaxation the maintenance dose had to be raised considerably (11.8-16.5 vs. 5.5 micrograms/kg per minute). These reports show that even within a short period of time resistance to atracurium can develop and we must suppose that the severe inflammatory reaction caused these changes.

Adult↗
PubMed1996

Limited applicability of the DATEX Reloxograph in diabetics with peripheral polyneuropathy.

The aim of the study was to investigate whether peripheral nerve dysfunction can influence the applicability of the DATEX Relaxograph in diabetics. Sixty two patients (43 diabetics, 19 non-diabetics) undergoing ophthalmosurgical procedures under general anesthesia were tested. The distal motor latency (DML) of the ulnar nerve served as a graduation tool for peripheral nerve dysfunction. The patients were divided in three groups: non-diabetics (group 1), diabetics with DML < 3.8 msec (group 2), diabetics with DML > 3.8 msec (group 3). Relaxometry was performed by stimulating the right ulnar nerve near the wrist, and the evoked response (EMG) was obtained from the hypothenar muscle. Calibration of the device (i.e. supramaximal stimulation within the given current range of a maximum of 70 mA) was carried out successfully in most patients of group 1 and 2 (94.7% and 85.7% respectively). In contrast to that calibration could be carried out in only 40.9% of the patients of group 3 (P < 0.01 vs. group 1 and 2). Consequently in a high percentage (59.1%) of the patients of group 3 relaxometry had to be performed in an uncalibrated manner. The results substantiate the hypothesis that peripheral nerve dysfunction can restrict the applicability of the Relaxograph in diabetics.

Anesthesia, General↗
PubMed1994

[Difficulties in the relaxometry of diabetics].

OBJECTIVE: Based upon clinical experience, peripheral nerve stimulation for neuromuscular monitoring under general anesthesia sometimes seems to be difficult in patients with diabetes mellitus. The aim of this study was to evaluate the applicability of the evoked electromyogram (EMG) in diabetics compared to non-diabetic controls. METHODS: 109 ophthalmosurgical patients (35 diabetics, 74 non-diabetics) were investigated. Relaxometry was performed by electrical stimulation of the ulnar nerve proximal of the wrist and the evoked EMG was recorded above the hypothenar muscle (Relaxograph, supplied by Datex). Immediately after induction of anaesthesia the calibration of the device was performed. RESULTS: The calibration of the relaxograph could be performed successfully only in 57.1% of the diabetics compared to 93.2% of the non-diabetics (p < 0.001). Consequently the uncalibrated mode had to be chosen more often in diabetics than in non-diabetics. In two non-diabetics and three diabetics no stimulation response could be achieved. Biometrical data, serum electrolyte concentrations, wrist circumference and body temperature were similar in both groups. The calibration mode could be performed in diabetics without peripheral polyneuropathy more often (76.5%) than in diabetics with peripheral polyneuropathy (38.9%) (p < 0.05). CONCLUSION: The results show that the applicability of the peripheral nerve stimulator in diabetic patients is more difficult than in non-diabetics. The disturbances of the peripheral nervous system seem to be responsible for these problems.

Adolescent↗
PubMed1993

[Halothane absorption by dry soda lime].

Humidified soda lime is commonly used to eliminate carbon dioxide from the circulatory system. Little is known about adverse reactions to accidentally dried soda lime. Therefore, a case of unexpected absorption of halothane by dry soda lime is reported. These observations were confirmed by a simulation with relevance to anaesthetic practice. CASE REPORT. A 46-year-old ASA class I patient was scheduled for elective surgery. After induction of general anaesthesia with 500 mg thiopentone, followed by 100 mg suxamethonium, the trachea was intubated. The patient was ventilated with nitrous oxide in oxygen and 1.5 vol% of halothane for several minutes in the induction room. After being connected to a new circulatory system in the operating theatre, the patient was ventilated but, in addition inspiratory and expiratory anaesthetic gas concentrations were measured. Despite a vaporizer position of 1.5 vol% the inspiratory concentration of halothane was below 0.2 vol%. Disconnecting the tube, the typical odour of halothane was missing in the inspiratory line of the circulatory system, but was present in the fresh gas tube. Furthermore, the lower part of the soda lime canister was surprisingly hot. After removing both the absorbers, the inspiratory halothane concentration immediately normalized. The absorbers were replaced by canisters filled with fresh soda lime, and the anaesthesia was terminated without further complications. An absorption of halothane by dried soda lime was suspected. METHODS OF SIMULATION. In the first simulation four circulatory systems with two soda lime canisters each were perfused with 21 of oxygen for 48 h. In the second simulation four soda lime canisters placed in one circulatory system were perfused with 1 l for 120 h. For measurement of halothane absorption each canister was placed in a circulatory system. The canister was perfused with a fresh gas flow of 2 l of oxygen and a vaporizer position up to 1.3 vol% of halothane. By the time an equilibrium was reached, i.e., in- and outflow concentrations of halothane were equal for a 3-min period, further halothane vaporization was stopped. In a 30-s interval the soda lime temperature and the gas concentration entering and leaving the soda lime canister were registered. Subsequently, the humidity of the soda lime was determined. RESULTS. In the first simulation 6 of the 8 canisters showed a humidity of soda lime of 15.5% of 19%, with halothane being absorbed in one case. Normally, the equilibrium between in- and outflow gas concentration was reached after 3.5-4 min. In the remaining two canisters the humidity was 14% and 9%. Only a small amount of halothane vapour was absorbed. The halothane concentrations were in equilibrium after 10 to 13 min. The probes from the second simulation revealed a humidity of soda lime of 2% to 8.7%. Below a humidity of 4% the concentration of halothane leaving the canister was greatly reduced. It took 63 min to reach a steady state in the 2% humidity probe and the temperature rose to 43.1 degrees C. CONCLUSIONS. Accidental perfusion of the circulatory system with dry oxygen can cause a reduction in the humidity of soda lime. Dried soda lime delays the increase of halothane concentration in the inspiratory limb. The absorption of halothane is accompanied by an increase in the temperature of the soda lime. Therefore, in every situation lacking a sufficient anaesthetic level during inhalation anaesthesia, absorption of the vaporized anaesthetic must be excluded. Only dried soda lime can absorb halothane.

Adsorption↗
PubMed1992

[Failure of relaxometry in diabetic polyneuropathy].

Disturbances of the peripheral nervous system, summarised under the term "diabetic polyneuropathy", are a well-known complication of long-term diabetes mellitus. However, there is little information about the fact that these conditions may lead to difficulties in monitoring neuromuscular blockade by peripheral nerve stimulation during general anaesthesia. We report two diabetic patients (40 resp. 62 years of age) in whom a total of four ophthalmological operations were performed under general anaesthesia. In all cases monitoring of neuromuscular transmission was attempted by stimulation of the left ulnar nerve slightly proximal to the wrist, but not even the usual calibration could be obtained in either patient. Checks confirmed that the nerve stimulator was functional and the electrodes--in all cases self-adhesive, pregelled surface electrodes--were placed correctly. In order to evaluate the hypothesis that disturbances of peripheral nerve function might be responsible, the patients were examined neurophysiologically in the postoperative period. Both patients showed severe alterations in peripheral nerve conduction: a sensory response could not be evoked in any of the extremities and the ulnar distal motor latency time was pathologically prolonged (5.4 ms in patient 1 and 4.9 ms in patient 2; normal: 1.4-4.0 ms). Therefore, in accordance with the clinical symptoms, the diagnosis of diabetic polyneuropathy was established. These cases demonstrate that severe disturbances of the peripheral nervous system may render neuromuscular monitoring impossible.

Adult↗
PubMed1990

Diabetic autonomic neuropathy: abnormal cardiovascular reactions under general anesthesia.

The influence of diabetic autonomic neuropathy upon the behavior of the circulatory system was investigated in 56 patients who had undergone ophthalmological surgery. A standardized test combination (variability in heart rate during deep breathing. Valsalva ratio, 30:15 ratio, change in blood pressure from lying to standing, sustained handgrip test) was used to study the patients' cardiovascular reflectory reactions. The patients were then divided into the following groups: Group I, non-diabetics. Group II, diabetics without autonomic neuropathy. Group III, diabetics with autonomic neuropathy. The anesthetic (induction by barbiturates and conduction by inhalation agents) and the surgical procedure (pars plana vitrectomy) were standardized and always identical. During anesthesia patients in group III experienced hypotensive reactions (systolic blood pressure below 90 mm Hg) significantly more often (72.2%) than patients in group I (25%). In order to achieve stability in blood pressure the patients of group III had to be given vasoactive drugs much more often (77.8%) than the patients of group I (12.5%) and those of group II (35.7%). We found a significant correlation between the degree of autonomic dysfunction and the largest drop in blood pressure under narcosis (r = -0.60, P less than 0.001). However, marked variability in heart rate and cardiac rhythm disorders during anesthesia were seen only in patients of groups I and II. These results prove the atypical hemodynamic behavior and especially the extreme instability in blood pressure in diabetic autonomic neuropathy under general anesthesia. Therefore we consider it to be very helpful to check the cardiovascular reflectory status of diabetics preoperatively.

Adult↗
PubMed1990

Restoring sinus rhythm after intraoperatively occurring isorhythmic AV dissociation by the use of K-Mg aspartate or Mg aspartate.

In a prospective randomized clinical trial we tested the efficiency of different electrolyte infusions for the treatment of intraoperatively occurring isorhythmic AV dissociation (ID). Only infusions containing Mg were effective in restoring sinus rhythm: the infusion of K-Mg aspartate led to a conversion of intraoperatively occurring ID into sinus rhythm in 72% (p less than 0.01) of the patients and the infusion with Mg aspartate alone did so in 67% (p less than 0.01) of the patients. The rate of spontaneous conversion was 22% in the control group treated with Ringer's solution. The use of infusions containing K aspartate was ineffective in restoring sinus rhythm.

Adolescent↗
PubMed1990

[Unstable blood pressure during anesthesia in diabetic patients with autonomic neuropathy].

Diabetic autonomic neuropathy (AN) as a risk factor of surgical procedures has so far been described in case reports, but no controlled clinical studies are known. Therefore, we intended to study systematically the perioperative relevance of the autonomic dysfunction. 32 ophthalmosurgical patients (20 diabetics, 12 non-diabetics) were investigated. Cardiovascular autonomic function was examined preoperatively by a combination of tests (heart rate variations during deep breathing, Valsalva ratio, 30:15 ratio, postural hypotension, sustained hand grip). A scoring system based on these tests provided the staging of the autonomic involvement of the patients (AN score). The anaesthesiological management (thiopentone, N2O, halothane) and the operative procedure (vitrectomy) were uniform. A significant correlation was found between the AN score and the coefficient of variation of the systolic (r = 0.70, p less than 0.001) resp. the diastolic (r = 0.52, p less than 0.01) blood pressure during anaesthesia. No correlation was found between the intraoperative variability of the arterial blood pressure (coefficient of variation) and the age of the patients resp. the preoperative value of the blood pressure. In diabetics with severe autonomic neuropathy (AN score greater than 5) hypotensive reactions were seen very often during the operation. The results demonstrate that the haemodynamic stability in the perioperative period depends on the severity of the autonomic dysfunction. Diabetics with severe autonomic neuropathy have a high risk of blood pressure instability. Non-invasive diagnostic methods allow to identify these patients preoperatively.

Adult↗
PubMed1989

[Air embolism in the sitting position. Oxygen/nitrogen versus oxygen/laughing gas].

UNLABELLED: Venous air embolism (VAE) is a well-known complication of neurosurgical procedures performed in the sitting position. Nitrous oxide (N2O) intensifies the hemodynamic alterations conditioned by VAE. Therefore the administration of N2O must be discontinued immediately if VAE occurs. Nevertheless, it is still not clear whether N2O should be avoided in such operations as a general policy. The aim of the present study was to investigate the incidence and severity of VAE with O2/N2 as opposed to O2/N2O anesthesia. METHODS. In all, 42 patients (19 men, 23 women) aged 23-80 years were investigated in a randomized order. In all cases an intracranial operation was carried out with the patient in the sitting position. The anesthesiologic management was uniform: modified neuroleptanalgesia (fentanyl, flunitrazepam, droperidol), relaxation with pancuronium, endotracheal intubation, moderate hyperventilation (PaCO2 30-35 mmHg) without PEEP. Half (21) of the patients (group 1) were ventilated with O2/N2 (1:1) and the remaining patients (group 2) with O2/N2O (1:1). Heart rate (HR) arterial blood pressure (AP), central venous pressure (CVP), end-tidal CO2 tension (PE'CO2), and body temperature were monitored continuously. Arterial blood gases were checked once per hour at least. VAE was signaled by changes in the ultrasonic Doppler sounds or a rapid decrease in the end-tidal CO2 tension. The diagnosis of VAE was confirmed by aspirating air bubbles through the right atrial catheter. A vacuum-driven device was used to suction off the embolized air and measure the aspirated air volume. Pulmonary gas exchange was defined by the arterial to end-tidal CO2 difference (PaCO2 - PE'CO2) and by the alveolar arterial O2 quotient (PAO2 - PaO2/PAO2). If a VAE was recognized N2O administration was stopped immediately and ventilation was continued with pure oxygen. Postoperatively all patients were ventilated. RESULTS: The incidence of VAE was similar in both groups: VAE occurred in five patients in group 1 and in six patients in group 2. In isolated cases distinct increases in the CO2 difference (PaCO2 - PE'CO2) or the O2 quotient (PAO2 - PaO2/PAO2) resulted, with no significant difference between the groups. In patients with VAE the aspirated gas volume (median 6.0 ml in group 1, 75.5 ml in group 2; P less than 0.01) and the duration of aspiration (median 5.0 min in group 1, 22.5 min in group 2; P less than 0.05) were significantly different in the two groups. HR was significantly lower in group 2 1 and 4 h after the beginning and at the end of the operation. MAP was significantly lower in group 2 3 and 4 h after the beginning and at the end of the operation. CVP was significantly higher in group 2 3 h after the start of the operation. The total dose of fentanyl, flunitrazepam and droperidol administered was higher in group 1 than in group 2 (P less than 0.05). The duration of postoperative ventilation was similar in both groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

[The diagnostic significance of disordered gas exchange in inhalation trauma].

52 patients with burn injuries were prospectively investigated. In all cases intubation was necessary because of clinical signs of smoke inhalation. We studied whether a correlation could be established between the clinical signs and bronchoscopic findings and the degree of gas exchange disorder. The disturbed oxygenation was defined by the average alveolo-arterial oxygen quotient of the first 24 hours. The inhalation injury was classified by clinical signs and bronchoscopic findings (inhalation injury score). The average alveolo-arterial O2-quotient of the first 24 hours and the inhalation injury score showed a high correlation coefficient (r = 0.77). No correlation was seen between the severity of gas exchange disorder and the amount of burned body surface area (r = 0.20) respectively the age of the patients (r = 0.27). According to these results early onset of disorders in gas exchange after burn injury reflects smoke inhalation. Therefore the gas analysis from arterial blood can be a very helpful diagnostic method and allows to estimate the degree of pulmonary damage by inhalation injury.

Adolescent↗
PubMed1989

[An increase in intracranial pressure following fentanyl].

We report an unusual fentanyl-induced reaction in an 8-year-old boy who had to be sedated and hyperventilated because of a severe head injury. Following the intravenous administration of a bolus of fentanyl, the intracranial pressure rose markedly for about 10 min. Simultaneously, the arterial blood pressure fell and heart rate increased, critically reducing the cerebral perfusion pressure temporarily. This reaction could be due to histamine-induced vasodilation.

Child↗