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R Hofmockel

Publications and source records attributed to R Hofmockel.

At least 19 recordsLinked to original sources
PubMed2007

Incidence and duration of residual paralysis at the end of surgery after multiple administrations of cisatracurium and rocuronium.

In a randomised, controlled, double-blind, multicentre trial in 338 patients, we assessed the incidence of residual paralysis following administration of cisatracurium or rocuronium. The incidence at the end of surgery was significantly lower in patients treated with rocuronium (62 of 142 patients, 44%) than in those given cisatracurium (99 of 175 patients, 57%) (p < 0.05). In contrast, with rocuronium the mean (SD) time between skin closure and extubation was 28 (28) min vs 18 (19) min for cisatracurium, and the duration 0.9 (time from administration of last top-up dose to recovery of the train-of-four ratio to 0.9) was significantly longer and more variable for rocuronium than for cisatracurium. Thus, after repeated administration, the duration and variability of duration of action are greater with rocuronium compared with cisatracurium. These pharmacodynamic differences do not necessarily translate into a higher incidence of residual paralysis, because clinicians compensate for the longer duration of action and variability of rocuronium by terminating administration of the neuromuscular blocking earlier.

Androstanols↗
PubMed2006

Onset properties of mivacurium measured by mechanomyography depend on the twitch height of the adductor pollicis muscle.

INTRODUCTION: The influence of the twitch height of the adductor pollicis muscle during baseline measurements on the pharmacodynamic parameters of mivacurium was prospectively evaluated. PATIENTS AND METHODS: Fifty adult patients were anaesthetized with propofol and alfentanil. Neuromuscular function was monitored mechanomyographically by measuring the force of the adductor pollicis muscle following stimulation of the ulnar nerve. Following a stabilization period of 20 min, the individual twitch height of the adductor pollicis muscle was determined before a single bolus of mivacurium (75 microg kg-1) was administered. Patients were divided into two groups. The data of patients whose thumb adduction force was below the median value of all patients were the 'low force' group (9.1 +/- 1.4 N) and the data of all other patients were the 'high force' group (13.7 +/- 1.8 N). RESULTS: In the 'high force' group, maximum neuromuscular blockade of mivacurium was deeper (0.97 +/- 0.05 vs. 0.93 +/- 0.06; P < 0.05) and onset faster (2.9 +/- 1.1 min vs. 4.0 +/- 1.2 min; P < 0.05). Neuromuscular recovery did not differ between the groups. CONCLUSION: The different onset speeds reflect either different sensitivity to neuromuscular blocking agents with respect to patients' muscle power or a problem of the mechanomyographic measuring technique.

Adult↗
PubMed2006

[Depth of anaesthesia during intubation: comparison between propofol and thiopentone].

In order to study the depth of anaesthesia during endotracheal intubation, 30 patients received either thiopentone or propofol for anaesthesia induction. The BIS value as a parameter for the depth of anaesthesia and the rate pressure product (RPP) were acquired online. Patients who received thiopentone for anaesthesia induction showed significantly higher BIS values at the moment of intubation and reached BIS values >60 significantly more frequently than patients receiving propofol. The RPP in the propofol group lay significantly below that of the thiopentone patients. For all patients there was an mean increase in BIS values of 8 index points and an increase in the RPP. Therefore, BIS values around 50 should be achieved before intubation in order to avoid the critical BIS value for awareness of >60 despite the increase caused by the intubation procedure. Within 24 h of intubation all patients were interviewed for possible signs of awareness. None of the patients was able to remember the intubation or reported other experiences that indicated an unconscious awareness. Nevertheless, the progress of BIS values in a standardized intubation as performed in the normal clinical routine, shows that the use of thiopentone for initiating anaesthesia results in a very flat level of anaesthesia during intubation. The risk for patients to experience awareness should therefore, not be underestimated. Therefore, when using thiopentone it is recommended to also use a rapid acting muscle relaxant or to select a high ED95 to compensate for the flat level of anaesthesia. Alternatively, repetetive boluses of the hypnotic shortly before intubation should be considered or to revert to propofol. The dosage and pharmacokinetics of the analgesic should also be taken into consideration because an insufficient analgesia leads to a faster flattening of the depth of anaesthesia.

Adolescent↗
PubMed2006

[Muscle relaxants in Germany 2005: a comparison of application customs in hospitals and private practices].

Aim of this study was to evaluate application customs of muscles relaxants in hospitals compared to their use in private practice. Of the 3,260 questionnaires sent-out, 66.9% could be analyzed. Of these 54% were from anesthetists in private practice, 41% from heads of hospital anesthesia departments and 5% from heads of level one hospital anesthesia departments. The first difference between private practices and hospitals was the number of available muscle relaxants: 87% of private practices use 1-3 relaxants, whereas 79% of hospitals use 3-5. Another apparent difference was the relationship between general anesthesia and the number of intubations: 60% of private practices have over 80% of general anesthesia cases, but only 50% of these patients are intubated. On the contrary, two thirds of the hospitals have 50-80% general anesthesia cases and 60-70% of patients are intubated. The main wish for an ideal muscle relaxant was independent of private practice or hospital, short onset time, followed by fast recovery. In accordance 74% of anesthetists in hospitals and 72% of anesthetists in private practice voiced the wish for a non-depolarizing succinylcholine substitute. The results of this nationwide survey suggest that time pressure in combination with an increased specialization of anesthetists in private practice are the main factors for availability and use of muscle relaxants in routine anesthesia.

Anesthesia↗
PubMed2006

Comparison of invasive and less-invasive techniques of cardiac output measurement under different haemodynamic conditions in a pig model.

BACKGROUND AND OBJECTIVE: Despite the introduction of various less-invasive concepts of cardiac output measurement, pulmonary arterial thermodilution is still the most common measurement technique. METHODS: This prospective controlled study was designed to compare different methods of cardiac output measurement simultaneously. Pulmonary arterial thermodilution, transpulmonary thermodilution (PiCCO), trans-oesophageal echo-Doppler probe (HemoSonic) and partial carbon dioxide rebreathing technique (NICO monitor) were evaluated against a peri-aortic transit-time flow-probe as reference method in a clinically relevant animal model. After approval from the Local Ethics Committee on Animal Research, the investigations were conducted in nine anesthetized domestic pigs. Systemic haemodynamics were modulated systematically by the application of catecholamines, caval occlusion and exsanguination. Statistical analysis was performed with Bland-Altman and linear regression. RESULTS: A total of 366 paired cardiac output measurements were carried out at a reference cardiac output between 0.5 and 7 L min(-1). The correlation coefficients for pulmonary arterial and transpulmonary thermodilution against reference were 0.93 and 0.95, for trans-oesophageal Doppler and partial rebreathing technique 0.84 and 0.77. Pulmonary arterial thermodilution and transpulmonary thermodilution showed comparable bias and limits of agreement. Where HemoSonic showed an overestimation of cardiac output at a higher precision, NICO overestimated low and underestimated higher cardiac output values. CONCLUSIONS: Our data suggest that pulmonary arterial thermodilution and PiCCO may be interchangeably used for cardiac output measurement even under acute haemodynamic changes. The method described by Bland and Altman demonstrated an overestimation of cardiac output for both thermodilution methods. HemoSonic and NICO offer non-invasive alternatives and complementary monitoring tools in numerous clinical situations. Trend monitoring and haemodynamic optimizing can be applied sufficiently, when absolute measures are judged critically in a clinical context. The use of the NICO system seems to be limited during acute circulatory changes.

Algorithms↗
PubMed2004

[Feedback control of muscle relaxation with a varying on-off controller using cisatracurium].

BACKGROUND: Under clinical conditions constant neuromuscular blockade can also be maintained by a simple closed-loop system. However, delayed onset time, non-linearity of the dose-response curve and different sensitivity to muscle relaxants for each patient are limiting factors. METHODS: In 20 patients who underwent elective surgical procedures under continuous propofol/alfentanil anaesthesia and relaxation with cisatracurium, the maintenance of an electromyographically controlled cisatracurium block of 90% was achieved by a varying on-off control system. Using an own computer-aided measuring device, the course of the neuromuscular blockade and deviations from the desired neuromuscular block were registered. RESULTS: Over a period of 64.2+/-14.0 min, neuromuscular block could be controlled on average at a T(1)-level of 10% (90% block). The mean error of the deviation of the obtained neuromuscular blockade from the set-point was -1.6+/-0.9% on average. To maintain this neuromuscular blockade, a dose rate of 1.4+/-0.9 micro g x kg(-1) x min(-1) cisatracurium was necessary. CONCLUSIONS: It can be concluded that a simple closed-loop system allows the safe use of the intermediate term muscle relaxant cisatracurium for the performance of surgical procedures.

Adult↗
PubMed2003

[The use of muscle relaxants for routine induction of anesthesia in Germany].

The aim of this study was to evaluate the use of muscle relaxants during induction of anesthesia in patients without risk of aspiration of stomach contents. Of the 2,996 questionnaires sent out, 2,054 (68.6%) could be analysed and the results show that succinylcholine is used regularly in 13.6% of anesthesia departments. The next most commonly used muscle relaxants are atracurium, vecuronium and mivacurium, followed by cis-atracrium, rocuronium and pancuronium. Alcuronium is the least frequently used muscle relaxant. During induction of an elective anesthesia procedure, a priming technique is used by 19% of anesthesiologists, 22% utilize precurarization, and a timing technique is performed in 7.1%. The use of muscle relaxants for on-going relaxation follows the same pattern as for induction of neuromuscular blockade and succinylcholine is used in 1.4% if further relaxation is needed. The desire for specific qualities of muscle relaxants is correlated with higher use of the specific substance: short onset time for rocuronium, good controllability with mivacurium, no side-effects with cisatracurium and economical aspects with alcuronium. Of the participants 76.6% voiced the desire for a non-depolarizing replacement for succinylcholine.Private practices use mivacurium more often than hospitals, level one hospitals use rocuronium and cisatracurium more often. This survey could not show a definite standard of use in terms of muscle relaxants for an elective case.Precurarization, priming and timing are used frequently in patients not at risk of aspiration. This should be reduced by on-going teaching.

Anesthesia↗
PubMed2003

[Application of muscle relaxants in Germany. A survey of German anaesthesia departments].

AIM: The aim of this study was to evaluate the use and application of muscle relaxants and neuromuscular monitoring in Germany. METHODS: A total of 2,996 questionnaires were sent out to the heads of German anaesthesia departments and private anaesthesia practices. The questions covered frequency of muscle relaxants used,how they were used, and neuromuscular monitoring. Influences on the way muscle relaxants were used could be derived from the desire for specific properties of a muscle relaxant, the desire for different monitoring conditions and from the size of the institution. We correlated these features with application practice using logistic regression analyses. RESULTS: Of the 2,996 questionnaires 2,058 could be analysed (68.6%). Amongst those were 102 level one hospitals (5%) and 903 private practices (44%). The replies from 350 (17%) departments were based on surveyed data, 1,613 (78.5%) were based on estimations. The desire for certain properties of muscle relaxants correlated with the use in practice, as were the desire for a non-depolarizing replacement for succinylcholine, the size of the department and the frequency of use of neuromuscular monitoring. Over 50% of all German anaesthesia departments limited the use of muscle relaxants to three. The use of laryngeal masks reduced the use of muscle relaxants. CONCLUSIONS: The survey regarding use of muscle relaxants in Germany could for the first time give an overview on the use of anaesthesia-specific substances in Germany. From the different frequencies of use and use modalities,conclusions could be drawn towards a standard of application for the year 2000. Changes in this standard would raise the need for further trend surveys. The methods of statistical analysis and survey evaluation can be used as a base for further surveys.

Anesthesia↗
PubMed2003

[Application of muscle relaxants for rapid-sequence induction of anaesthesia].

The present study evaluates the use of muscle relaxants for rapid-sequence induction (RSI) and different application techniques (pre-curarisation, priming, timing) as a part of a nationwide survey in Germany. In 86.8% of anaesthesia departments succinylcholine is used for RSI and an average of 56.5% of respondents used only succinylcholine for RSI. Of all non-depolarising muscle relaxants rocuronium is the most frequently used alternative. Of the anaesthesia departments 2.6% use rocuronium regularly in patients with increased risk for aspiration of stomach contents; level one centres significantly more than others, 12.9% answered that pre-curarisation techniques were never used, whereas 45.6% use non-depolarising neuromuscular blocking drugs before giving succinylcholine in 80-100% of cases. Priming is not used by 64.4% of respondents, as opposed to 9.8% who utilise this technique regularly. The statements regarding timing are 71.1% and 5.4%, respectively. Alcuronium is used for RSI in departments in which the financial aspect is the primary decision criteria. Despite ist known side-effects and the on-going discussion over the past years, succinylcholine is still the most frequently used muscle relaxants for RSI. Priming is often declined by anaesthetists in Germany, most probably due to the absence of clear advantages and the possibility of severe complications. It is the opinion of the authors that timing but also drugs with a slow onset (e.g., alcuronium and Pancuronium) are obsolete in the context of RSI.

Alcuronium↗
PubMed2003

[The use of neuromuscular monitoring in Germany].

AIM: As there are no reliable epidemiological data for the use of muscle relaxants in Germany,we conducted a mailing study. The aim of the study was to compare the use of muscle relaxants between German anaesthesia departments. In the present part of the presentation we focused on neuromuscular monitoring (NMM) and management of residual paralysis. METHODS: A total number of 2,996 questionnaires were sent to all registered anaesthesiological facilities in Germany and the return was 68.6% (2054 questionnaires). RESULTS: In 574 of the returned questionnaires (28%) the regular use of NMM was confirmed. Intraoperative monitoring of neuromuscular block and assessment of neuromuscular recovery were the most frequent applications of NMM, i.e. 25% and 18% of returned questionnaires, respectively. Clinical signs, however, are still the most popular way to estimate the degree of neuromuscular blockade. Moreover, routine reversal at the end of surgery with a neostigmin/atropine mixture was not practiced in 75% of the anaesthesia departments. CONCLUSIONS: This survey revealed that NMM is still very rarely used in daily clinical practice. Especially the seldom use of NMM to assess residual paralysis has to be improved.

Anesthesiology↗
PubMed2003

[The syringe pump as actuator--a practical application problem of feedback control systems].

Based on a computer simulation programme, the accuracy of the Graseby 3400 syringe pump was tested for its use in a feedback control system of the neuromuscular block. Firstly, a calculation of errors to determine the difference between the target and actual flow rates was carried out. Next, the characteristic curves of the syringe pump were determined under different flow and sampling rates to correct the application software of the feedback controller with a view to obtaining the correct flow rates online. It was discovered that, particularly with short 12 s sampling rates, dose-dependent errors of almost 100% were provable. Therefore, the application of a robust controller and integration of the characteristic curves at the outlet of the controller software are required. For the adoption of syringe pumps in medical feedback control systems, definite determination of the actual infusion quantity using an exact calculation of errors is required. Especially in cases of short sampling rates in combination with low infusion quantities, the syringe pump comes almost to a standstill, which results in extreme differences between target and actual flow rates.

Computer Simulation↗
PubMed2002

Double-blind comparison of the variability in spontaneous recovery of cisatracurium- and vecuronium-induced neuromuscular block in adult and elderly patients.

BACKGROUND: This study was designed to compare variability in the offset of two neuromuscular blocking agents with different elimination pathways. METHODS: The spontaneous recovery profiles of cisatracurium and vecuronium were compared in adult (18-64 years) and elderly (> or =65 years) patients receiving N2O/O2/fentanyl/propofol anaesthesia. Patients were randomised to receive an initial bolus dose and maintenance doses of 3xED95, respectively, 0.6xED95 for cisatracurium (0.15 and 0.03 mg.kg-1) or 2xED95, respectively, and 0.4xED95 for vecuronium (0.1 and 0.02 mg.kg(-1)), as recommended in their prescribing information. Administration of the study drugs was double-blinded, and neuromuscular transmission was monitored using mechanomyography of the evoked response of the adductor pollicis, following ulnar nerve stimulation. RESULTS: The clinically effective duration (minutes) of the initial bolus dose, defined as the mean time to 25% T1 recovery (+/-SD), for the adult and elderly patients was 53.5+/-9.8 and 57.3+/-11.5 for cisatracurium, respectively, and 34.1+/-9.0 and 47.5+/-14.4 for vecuronium, respectively. The duration of spontaneous sufficient recovery (SSR), defined as the mean (+/-SD) time interval in minutes from 25% T1 recovery to a T4:T1 ratio > or =0.8 after the last bolus dose, for the adult, respectively, elderly patients was 28.3+/-8.0 and 31.7+/-10.0 for cisatracurium and 38.5+/-13.2 and 60.3+/-26.1 for vecuronium. CONCLUSION: Whereas both the clinically effective duration and the duration of SSR are comparable between the adult and the elderly patients receiving cisatracurium, they differ substantially between these two age groups for vecuronium. Furthermore, the variability in offset is significantly lower in patients receiving cisatracurium, especially in the elderly, which may be of particular clinical interest.

Adolescent↗
PubMed2002

[Oral and rectal premedication of children with midazolam]].

Premedication in children continues to be a problem in anaesthesiology. Apart from the application of premedication drugs, a strongly committed anaesthetist and sound psychological work are decisive prerequisites for adequate premedication. In this randomized study, 329 children aged between 1 and 14 who were scheduled for small surgical procedures were examined. Based on the results of a preliminary trial using different dosages of midazolam, the children were premedicated either orally with 0.4 mg/kg BW midazolam or with 0.3 mg/kg BW midazolam as a rectal solution and the premedication effect was recorded according to the classification of Lindgren. These reduced doses of midazolam, which were much lower than those described in the literature, led to very good premedication effects, too. Regarding cardiovascular behaviour, an increasing anxiolysis and the effect of premedication led to a significant decline in mean arterial blood pressure and heart frequency. The circulatory changes that occurred were at no time clinically relevant in any child, and therefore no treatment was needed. Based on the measured oxygen saturation, no significant respiratory changes were seen during the observation period. The frequency and extent of the registered side-effects were classified as slight. Side-effects such as singultus, salivation and ataxia/gesticulations were of no danger during the entire perioperative period.

Adjuvants, Anesthesia↗
PubMed2002

[Quantitative assessment of neuromuscular block of the orbicularis oculi muscle].

In a prospective clinical study neuromuscular block at the orbicular ocular muscle was examined qualitatively and quantitatively by an AMG approach. The signals were recorded, visualized and evaluated simultaneously under PC-support after TOF-stimulation in 20 s intervals. Fifty ASA I and II patients were included into the study. After oral premedication with midazolam 10-15 mg, anaesthesia was induced with propofol 2 mg/kg and alfentanil 0.02 mg/kg and maintained by means of propofol 6-8 mg/kg/h and alfentanil 0.02 mg/kg/h. After intubation and signal stabilization, mivacurium 0.75 mg/kg was administered and neuromuscular blockade was recorded online. The measured acceleration at the orbicular ocular muscle amounted 0.9 g on average. Maximal neuromuscular block was registered at 78.5% and the TOF-ratio of 0.8 was achieved after 14.1 min. The low values of the AMG-signals of the orbicular ocular muscle requiring very high technical demands on the measuring instrument. Additional problems arise through the considerable temporal expenditure for discovering the optimal location of stimulation. During the AMG monitoring the position dependence of the measured values of the sensors must be taken into consideration. These technical problems restrict the suitability of the AMG at the orbicular ocular muscle as a quantitative neuromuscular monitoring tool.

Adolescent↗
PubMed2001

[Clinical administration of muscle relaxants for intubation].

Muscle relaxants are used for tracheal intubation, surgical procedures and in the intensive care unit. This review describes muscle relaxants available in Germany, with special focus on their use in endotracheal intubation. We compare the advantages and disadvantages of succinylcholine (the only depolarising agent) with those of short- and intermediate-acting non-depolarising agents in an attempt to define the characteristics of the ideal muscle relaxant. The effective doses required to attain 95% neuromuscular block and maximum effect (onset time) are compared for adults and children. It is documented that, with non-depolarising agents, increasing the dose and using either the priming or timing principle possibly reduce the onset time of neuromuscular block during a rapid sequence induction. The advantages and disadvantages of using non-depolarising instead of depolarising agents are discussed using data from our studies and those of other research groups. Possible side-effects due to the chemical structure and the necessary dosage for intubation of different agents are also discussed. Two points are emphasized: firstly, the use of non-depolarising agents for intubation requires the possibility of safe ventilation of the patient via mask, and, secondly, it is important that procedures be performed by an experienced anaesthetist.

Adult↗
PubMed1998

[Sore throat after use of the laryngeal mask and intubation].

The laryngeal mask was developed by Brain in 1981 and described for the first time in 1983. It has been applied a few million times worldwide since 1988. One of the main complication is soreness of the throat. Two hundred unselected patients who had gynaecological procedures under general anaesthesia--100 under laryngeal mask airway and 100 under intubation--were surveyed to ascertain the incidence of sore throats under laryngeal mask airway. Each patient was asked about soreness of the throat during the next two days. The incidence and duration of sore throats were recorded using a pain scale (0-100). After narcoses with the laryngeal mask, 63 patients had no complaints. Thirty-seven had sore throats with an average pain score of 8.1 +/- 13.8 on the day of operation. The average pain scores showed a decreasing tendency (4.2 +/- 9.5 and 0.4 +/- 2.6) for the first and second postoperative day. After intubation narcoses, we recorded sore throats significantly more frequently (p < 0.05) and the average pain score on the day of operation was significantly higher (13.2 +/- 17.5; p < 0.05) than after narcoses with the laryngeal mask. Also after narcoses with the laryngeal mask, the average pain scores decreased quickly on the first and second postoperative days (5.1 +/- 9.0 and 0.2 +/- 1.4). There were no differences regarding sore throats between narcoses with the laryngeal mask or intubation on these two postoperative days. Using both anaesthesiological methods, sore throat was not related to duration of anaesthesia or the experience of the anaesthetist.

Adolescent↗
PubMed1997

[Comparison of dosage relations of prilocaine and bupivacaine for axillary plexus anesthesia].

The effects of 40 ml of prilocaine 1% compared to 30 ml prilocaine 1% added to 10 ml bupivacaine 0.5% and 20 ml prilocaine 1% added to 20 ml bupivacaine 0.5% after injection into the brachial plexus sheath were evaluated. In a prospective study, 90 patients who underwent surgery on the upper limb were randomly allocated to one of these three groups. In each group 15 patients were treated using nerve stimulation with an immobile needle and 15 using a plexus catheter. We assessed the sensory and motor blockade of the appropriate nerves every 5 minutes after injection for a period of 45 minutes (pin-prick testing or strength of the appropriate muscles). Postoperatively the patients documented the strength of their pain on a score of 0 to 10 four hours, six hours and 24 hours after injection. There were no differences in onset time between the groups, the operation normally starting after about 30 minutes. Compared to other nerves, blockade of the musculocutaneous nerve was delayed and not as complete. The quality of the blockade of the radial nerve was not worse than that of the ulnar and median nerve. Eighty-four patients were operated on in regional anaesthesia, 74 patients without supplementary measures. There were no differences in postoperative pain between the two different techniques. Significant differences, however, were found between the three drug groups: Patients given 40 ml of prilocaine 1% documented pain (0.75) 4 hours after injection; the other two groups reported nearly none. Six hours after injection the patients who had received 40 ml of prilocaine 1% had significantly more pain (2.25) than patients who had received 30 ml of prilocaine 1% plus 10 ml of bupivacaine 0.5% (0.96); patients who had received 20 ml of prilocaine 1% plus 20 ml of bupivacaine 0.5% had nearly no pain (0.19). We can conclude that mixing of prilocaine 1% with bupivacaine 0.5% is a useful way to achieve adequate duration of anaesthesia and to reduce postoperative pain without extending onset times for axillary plexus block. Postoperative application of analgetics can often be avoided completely.

Adult↗