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J M Wierda

Publications and source records attributed to J M Wierda.

At least 19 recordsLinked to original sources
PubMed2001

Biphasic EEG changes in relation to loss of consciousness during induction with thiopental, propofol, etomidate, midazolam or sevoflurane.

The time course of four EEG effect variables, amplitude in the 2-5 Hz and in the 11-15 Hz band, spectral edge frequency 95% (SEF95), and bispectral index (BIS), in response to increasing concentrations of thiopental, propofol, etomidate, midazolam, or sevoflurane during a 10 min induction of anaesthesia was studied in 25 patients to determine the existence of a biphasic effect and to study the relationship of the EEG effect to the moment of loss of consciousness. A biphasic effect, that is, an initial increase of the effect variable followed by a decrease at higher concentrations, during the transition from consciousness to unconsciousness was found in EEG amplitude (both frequency bands) and in SEF95 for all anaesthetics except midazolam. There was a concentration-related decrease in BIS for all anaesthetics. There was no consistent relationship between the time of occurrence of the peak EEG effect, or the value of the EEG variable and the moment of loss of consciousness. With rapidly changing drug concentrations during the induction of anaesthesia, none of these EEG effect variables could be correlated to the moment of loss of consciousness.

Adolescent↗
PubMed2001

Predictability of processed electroencephalography effects on the basis of pharmacokinetic-pharmacodynamic modeling during repeated propofol infusions in patients with extradural analgesia.

BACKGROUND: Pharmacokinetic-pharmacodynamic (PKPD) modeling can be used to characterize the concentration-effect relation of drugs. If the concentration-effect relation of a hypnotic drug is stable over time, an effect parameter derived from the processed electroencephalographic signal may be used to control the infusion for hypnosis. Therefore, the stability of the propofol concentration-electroencephalographic effect relation over time was investigated under non-steady state conditions. METHODS: Three propofol infusions (25 mg x kg(-1) x h(-1) for 10 min, 22 mg x kg(-1) x h(-1) for 10 min, and 12.5 mg x kg(-1) x h(-1) for 20 min) were administered to 10 patients during extradural analgesia. Each successive infusion was started immediately after the patient had regained responsiveness after termination of the preceding infusion. Electroencephalography was recorded from bilateral prefrontal to mastoid leads. Electroencephalographic amplitude in the 11- to 15-Hz band and the Bispectral Index were used as electroencephalographic effect variables. PKPD parameters were calculated with use of parametric and nonparametric models based on electroencephalographic data and arterial propofol concentrations derived during the initial infusion, and these were used to predict electroencephalographic effect during the subsequent infusions. The predictability of the electroencephalographic effects was determined by the coefficient of determination (R2) and of the -2 log likelihood of the sequential infusions. RESULTS: The direction of electroencephalographic changes in response to the infusions was reproducible. Although PKPD parameters could be estimated well during the initial infusion (median [range] parametric R2 = 0.74 [0.56-0.95] for electroencephalographic amplitude and 0.90 [0.27-0.99] for Bispectral Index), none of the modeling techniques could predict accurately the electroencephalographic effect during subsequent infusions (R2 = 0.00 [-0.31-0.46] for electroencephalographic amplitude and 0.15 [-.46-0.57] for Bispectral Index; P < 0.01). CONCLUSIONS: The relation between blood propofol concentrations and the electroencephalographic effect under non-steady state conditions is not stable over time and is too complex to be modeled by any of the applied PKPD models.

Adult↗
PubMed2001

A practical clinical approach to management of the difficult airway.

Difficult airway management represents a challenge in anaesthesia. In the last decades airway difficulty awareness has improved as a result of better anticipation and decision-making. Airway algorithms and protocols have a more prominent role in training and in clinical anaesthesia practice. In addition, several new instruments and therefore new techniques have been developed. These have improved possibilities for the clinician to secure the airway. Clinicians should become familiar with this equipment and techniques by using them on a regular basis in elective cases. The instruments available must be selected by the characteristics of the patient population, the local circumstances and the experience of the anaesthesiologist. The aim of this paper is to provide some practical guidelines with respect to airway difficulty predictors and airway instrument choice.

Airway Obstruction↗
PubMed2000

The relationship between rate of administration of an intubating dose of rocuronium and time to 50% and 90% block at the adductor pollicis muscle.

OBJECTIVE: To determine the relationship between the rate of rocuronium injection and the onset time of neuromuscular block. METHODS: After intravenous induction, 60 female patients (ASA I-II) were assigned randomly into 3 groups for rocuronium administration within 1-15, 15-30 or 30-60 seconds. Acceleromyography of the thumb was performed using train-of-four (TOF) stimulation. Times to 50% and 90% twitch depression of the first twitch of the TOF stimulation (T1) were recorded. RESULTS: Injection time significantly influences time to 50% relaxation, but not time to 90% relaxation. Body mass index is negatively correlated with time to 50% and 90% relaxation. CONCLUSIONS: We conclude that rate of injection influences only the initial phase of development of the block and that slower injection times do not significantly affect time to 90% relaxation at the adductor pollicis muscle.

Adolescent↗
PubMed2000

The effect of single twitch and train-of-four stimulation on twitch forces during stable neuromuscular block.

OBJECTIVE: We investigated whether the response to a single twitch (ST) stimulus or the first response (T1) to a train-of-four (TOF; 4 stimuli at 2 Hz) stimulus following a stimulus interval of 10 s (i.e., the time between two consecutive ST or TOF stimuli) is influenced by the preceding stimulus in the presence of a stable 50% neuromuscular block. In addition, we determined whether ST and TOF stimulation yield different results under these circumstances. METHODS: Twitch forces were measured in both tibialis anterior muscles of six cats. In the presence of a stable 50% neuromuscular block the stimulation pattern (ST or TOF) or stimulus interval (3.3, 10 or 30 s) was varied every 30 min. A linear mixed model was used for statistical analysis. RESULTS: ST forces with a stimulus interval of 3.3 s were 10.3% (95% CI: 7.3-13.3%) smaller than those with a stimulus interval of 10 s. For T1 forces this effect was 15.2% (95% CI: 12-18.4%). There was no significant difference between twitch forces with stimulus intervals of 30 and 10 s. For a stimulus interval of 3.3 s the ST forces exceeded the T1 forces by 7.6% (95% CI: 4.4-10.8%); no significant differences were found between the ST and T1 forces for stimulus intervals of 10 and 30 s. CONCLUSIONS: The ST or T1 force during stimulation with a stimulus interval of 10 s or more during a stable 50% neuromuscular block in the tibialis anterior muscle of the cat is not affected by the preceding stimulus. In addition, ST and T1 forces do not differ when employing a stimulus interval of 10 s or more under these circumstances. Our results thus indicate that the known differences between ST and T1 forces after a bolus injection of a muscle relaxant can not be explained by differences in acetylcholine release when the stimulus interval exceeds 10 s.

Anesthesia, General↗
PubMed2000

Urinary, biliary and faecal excretion of rocuronium in humans.

The excretion of rocuronium and its potential metabolites was studied in 38 anaesthetized patients, ASA I-III and 21-69 yr old. Rocuronium bromide was administered as an i.v. bolus dose of 0.3 or 0.9 mg kg-1. In Part A of the study, the excretion into urine and bile, and the liver content were studied. Plasma kinetics (n = 19) were similar to those reported previously. Urinary recovery within 48 h after administration was 26 (8)% (mean (SD)) (n = 8) of the dose. In bile obtained from T-drains, the recovery within 48 h was 7 (6)% (n = 11). The rocuronium concentration in bile declined bi-exponentially, with half-lives of 2.3 (0.7) and 16 (11) h respectively (n = 6). In three patients from whom stoma fluid was collected, the amount of rocuronium recovered ranged from 0.04 to 12.0% of the dose. In liver tissue obtained from four patients undergoing hemihepatectomy, the estimated amount of rocuronium at 2-5 h after administration ranged between 6.3 and 13.2% (n = 4). In the second part of the study (Part B), urine and faeces were collected over 4-8 days and the recovery was 27 (13)% and 31 (23)% of the dose respectively (n = 10). In most samples, irrespective of the type of biological material, only small amounts of the metabolite 17-desacetyl-rocuronium was found. The results demonstrate that rocuronium is taken up by the liver and excreted into bile in high concentrations. The faecal and urinary excretion of unchanged rocuronium are the major routes of rocuronium elimination.

Adult↗
PubMed2000

Rapacuronium 2.0 or 2.5 mg kg-1 for rapid-sequence induction: comparison with succinylcholine 1.0 mg kg-1.

The purpose of this nine-centre study in 602 patients was to show that the frequency of acceptable intubating conditions after rapacuronium 2.0 or 2.5 mg kg-1 is not more than 10% lower than the frequency after succinylcholine 1.0 mg kg-1 during rapid-sequence induction of anaesthesia with fentanyl 1-2 micrograms kg-1 and thiopental 2-7 mg kg-1. Laryngoscopy and intubation were carried out 60 s after administration of muscle relaxant by an anaesthetist blinded to its identity. Intubating conditions were clinically acceptable (excellent or good) in 91.8% of patients given succinylcholine and in 84.1 and 87.6% of patients given rapacuronium 2.0 and 2.5 mg kg-1 respectively. With respect to the percentage of clinically acceptable intubating conditions, the estimated difference (and the upper limit of the one-sided 97.5% confidence interval) between succinylcholine and rapacuronium 2.0 mg kg-1 was 7.8 (14.4)% and between succinylcholine and rapacuronium 2.5 mg kg-1 it was 4.0 (10.2)%. For both comparisons, the upper limit of the one-sided confidence interval exceeded the predefined 10% difference. Hence, it could not be demonstrated that the intubating conditions with either of the two doses of rapacuronium were not inferior to those with succinylcholine 1.0 mg kg-1. The increase in heart rate was significantly greater during the first 5 min in the rapacuronium groups, but the arterial pressure increased significantly only in the succinylcholine group (P < 0.001). Respiratory side-effects were observed in 4.0, 13.5 and 18.5% of patients after succinylcholine and rapacuronium 2.0 and 2.5 mg kg-1 respectively (P < 0.05). As the non-inferiority of intubating conditions after rapacuronium 2.0 and 2.5 mg kg-1 could not be proven, succinylcholine should be considered the neuromuscular blocking agent that provides better intubating conditions for rapid-sequence induction.

Adolescent↗
PubMed2000

Structure-pharmacokinetics relationship of series of aminosteroidal neuromuscular blocking agents in the cat.

To obtain more insight in the relationship between physicochemical properties of neuromuscular blocking agents (NMBAs) and their pharmacokinetic characteristics, a series of 12 aminosteroidal NMBAs, supplemented with data on five related NMBAs from the literature, was investigated in anaesthetized cats. After i.v. bolus injection, plasma concentration decreased very rapidly, showing a biphasic pattern, with half-lives ranging from 0.4 to 1.4 min, and from 3 to 10 min, respectively. Clearance was in the range from 24 to 58 ml. min(-1). kg(-1). Compounds containing an acetyl-ester group at position 3 were partly metabolized to the 3-OH derivative. The urinary excretion of the parent drug and metabolites amounted to <10% for each of the compounds. The parent drugs were excreted in large amounts into bile, along with smaller amounts of 3-OH derivatives. The terminal half-life of the urinary and biliary excretion rate were markedly longer than the apparent terminal half-life in plasma, ranging from 11 to 40 min, and from 119 to 489 min in urine and bile, respectively. Lipophilicity of the NMBAs, expressed as the partition coefficient octanol/Krebs (log P), was found to be correlated positively with unbound plasma clearance and unbound initial plasma clearance, and negatively with plasma half-life, volume of distribution at steady state, and mean residence time. The increase of the unbound plasma clearance with increasing lipophilicity is counteracted by the concurrent increase in plasma protein binding.

Animals↗
PubMed1999

Transient nerve damage following intubation for trans-sphenoidal hypophysectomy.

PURPOSE: To describe a case of transient lingual and hypoglossal nerve damage following intubation for a trans-sphenoidal hypophysectomy. CLINICAL FEATURES: A 56-yr-old acromegalic man was scheduled for trans-sphenoidal hypophysectomy. He had been treated with octreotide six months previously which had reduced the swelling of the tongue to an acceptable degree to the patient. During the anesthetic procedure there were no problems. The intubation was performed without any difficulty, no force had been used to place the endotracheal tube, a throat pack was inserted and, before extubation, an oro-gastric tube was inserted. Three days after surgery the patient complained of numbness and swelling of the left side of the tongue, he had difficulty in moving the tongue, speaking difficulties and problems in swallowing food were noted. Also taste was lost on this side of the tongue. Left lingual and hypoglossal nerve damage was diagnosed, which was confirmed by the neurologist. After four months of intensive physiotherapy and speech therapy, the symptoms disappeared. CONCLUSION: This is a report of a very rare complication of lingual and hypoglossal nerve damage in an acromegalic patient. This incident suggests forceful laryngoscopy, hyperextension of the head and the throat pack (tightly packed in the oropharynx) can result in injury of the lingual and the hypoglossal nerves.

Acromegaly↗
PubMed1999

Prevention of hypotension after induction of anesthesia after preoperative tune-up. A preliminary report of the Groningen Tune-up Study.

OBJECTIVE: To investigate whether the frequently occurring hypotension after induction of anesthesia can be prevented by preoperative treatment at the ICU guided by hemodynamic data obtained from a pulmonary artery (PA) catheter. DESIGN: Prospective controlled open randomized single center study. SETTING: University tertiary referral hospital. PATIENTS: Thirty-one patients undergoing major vascular- or abdominal surgery. INTERVENTIONS: Patients were randomized to either the control group or the ICU group. Patients allocated for the ICU group were admitted to the ICU the day before the operation and treatment was started aimed at a CI > or = 4.0 l/min/m2. No special treatment was given to the control group the day before the operation. Anesthesia was induced with etomidate, rocuronium and sufentanil. MEASUREMENTS AND MAIN RESULTS: Seventeen patients were allocated for the control group and 14 for the ICU-group. Mean ages were 65 +/- 2.5 and 66 +/- 2.5 years, respectively. Both groups were comparable regarding age, sex, blood pressure and type of operation. Filling pressures at admission on the ICU were: central venous pressure 3 +/- 2 mm Hg and pulmonary capillary wedge pressure 8 +/- 3 mm Hg while CI was 3.2 +/- 0.8 l/min/m2. The hemodynamic goal was achieved in all 14 patients of the ICU-group preoperatively with a background infusion of three l/24 h crystalloids, after a mean infusion of 1623 +/- 552 ml colloids, and in seven patients a median dose of 3 micrograms/kg/min (range 2-6) dopamine. Blood pressure before induction was comparable in both groups. The fall in systolic BP 10 min after induction of anesthesia was 22 +/- 18 in the ICU-group versus 41 +/- 17 mm Hg in the control group (p = 0.004). The fall in diastolic BP was 11 +/- 6 mm Hg in the ICU group versus 25 +/- 11 mm Hg in the control group (p = 0.0003). No differences between the groups in changes of heart rate were observed: a decrease of 13 +/- 7 bpm (95% confidence intervals 8.5 to 17.0) in the ICU group versus 15 +/- 14 (95% confidence intervals 7.6 to 21.9) bpm in the control group (p = 0.6). CONCLUSIONS: Hypotension after induction of anesthesia is significantly attenuated by preoperative treatment aiming at a CI > or = 4.0 l/min/m2 in high risk patients planned for major vascular- or abdominal surgery.

Aged↗
PubMed1999

The effect of maintaining a constant preload or a constant degree of thumb abduction in the isometric twitch force of the thumb.

OBJECTIVE: To investigate the effects of maintaining a constant preload and of maintaining a constant degree of thumb abduction on the isometric twitch force during mechanomyography of the thumb, we monitored neuromuscular function in patients anaesthetized without the use of a neuromuscular blocking agent. In addition, we studied the relationship between the degree of thumb abduction, twitch force and preload. METHODS: Fourteen patients were divided randomly into two groups, determining the sequence of the experiments in respect of correcting the preload and maintaining a constant degree of abduction after allowing the twitch forces to stabilize. Both experiments lasted 15 minutes. In both groups the relationship between the degree of thumb abduction, twitch force and preload was studied. RESULTS: We found a progressive increase in twitch force both with (6.6%; CI: 3.7-9.3%; p < 0.001) and without (1.9%; CI: 0.4-3.5%; p = 0.020) continuous correction of the thumb preload. A significant greater increase in twitch force was seen when the preload had been corrected than when it was not (4.7%; CI: 0.8-8.7%; p = 0.023). In addition, both twitch force and preload appeared to depend on the degree of thumb abduction both before and at the time of measurement. CONCLUSIONS: Changes in length of the contracting muscle fibres and creep phenomena in the connective tissue of the muscles, both leading to changes in the sarcomere length of the muscle fibres, may explain the observations in this study. In general, a stabilized preload at a constant degree of abduction seems to be required in order to obtain a stable twitch force.

Adult↗
PubMed1999

Increase in twitch force of the adductor pollicis muscle with stabilized preload at constant thumb abduction before and after administration of muscle relaxant.

OBJECTIVE: To determine whether the twitch force of the adductor pollicis remains stable when 0.1 Hz single twitch stimulation is started after stabilization of the thumb preload at a constant degree of thumb abduction; also to study any possible increase in twitch force before the onset of and after the recovery from neuromuscular block. METHODS: Measurements were performed in thirty patients under general anaesthesia. Twitch forces were first allowed to stabilize after allowing the preload to drift to its resting tension at a constant degree of thumb abduction. Three groups of ten patients then each received either vecuronium (2, 4, 8, 16 and 32 microg/kg(-1), successively at intervals of 2 min), d-tubocurarine (5, 10, 20, 40 and 80 microg/kg(-1), successively at intervals of 2 min), or suxamethonium (0.025, 0.05, 0.1, 0.2 and 0.4 mg/kg(-1), successively at intervals of 2 min). Measurements were continued until twitch forces had recovered from neuromuscular block and were stable. RESULTS: Twitch forces stabilized at 114% (sd = 8.9) of the initial value after 10.9 (6.1) min of stimulation. Increase in twitch force before the onset of neuromuscular block was seen in two patients receiving vecuronium and in two patients receiving d-tubocurarine. Increase in twitch force after recovery from neuromuscular block was seen in all patients receiving suxamethonium. CONCLUSIONS: Twitch forces may increase when stimulation is started after stabilization of thumb preload at a constant degree of thumb abduction. In some patients twitch forces may increase before the onset of neuromuscular block with vecuronium or d-tubocurarine; twitch forces increase after recovery from suxamethonium.

Adult↗
PubMed1999

Do plasma concentrations obtained from early arterial blood sampling improve pharmacokinetic/pharmacodynamic modeling?

In pharmacokinetic/pharmacodynamic (PK/PD) modeling the first blood sample is usually taken 1 to 2 min after drug administration (late sampling). Therefore, investigators have to extrapolate the plasma concentration to Time 0. Extrapolation, however, erroneously assumes instantaneous and complete mixing of drug in the central volume of distribution. We investigated whether plasma concentrations obtained from early arterial blood sampling would improve PK/PD modeling. In 14 pigs, one of five neuromuscular blocking agents (NMBAs) was administered into the right ventricle within 1 sec and arterial sampling was performed every 1.2 sec (1st min). The response of the tibialis muscle was measured mechanomyographically. The influence of inclusion of data from early arterial sampling on PK/PD modeling was determined. Furthermore, the concentrations in the effect compartment at 50% block (EC50) derived from modeling were compared to the measured concentration in plasma during a steady state 50% block. A very high peak in arterial plasma concentration was seen within 20 sec after administration of the NMBA. Extensive modeling revealed that plasma concentrations obtained from early arterial blood sampling improve PK/PD modeling. Independent of the type of modeling, the EC50 and KeO based on data sets that include early arterial blood sampling were, for all five NMBAs, significantly higher and lower respectively, than those based on data sets obtained from late sampling. Early arterial sampling shows that the mixing of the NMBA in the central volume of distribution is incomplete. A parametric PD (sigmoid Emax) model could not describe the time course of effect of the NMBAs adequately.

Animals↗
PubMed1999

The use of neuromuscular blocking agents in noncardiac surgery after dynamic cardiomyoplasty.

Dynamic cardiomyoplasty is a surgical treatment to improve cardiac performance in patients with end-stage heart failure by wrapping the latissimus dorsi muscle around the heart. The use of skeletal muscle raises concerns about the safety of neuromuscular blocking agents used during general anaesthesia in noncardiac surgery in patients after cardiomyoplasty. We describe the administration of rocuronium to a patient undergoing carotid endarterectomy 18 months after cardiomyoplasty. No clinically relevant effects on haemodynamics were observed. We conclude that the use of nondepolarising neuromuscular blocking agents for noncardiac surgery in patients after cardiomyoplasty does not compromise cardiac performance in a clinically relevant way, although the time between the cardiomyoplasty procedure and the use of nondepolarising neuromuscular blocking agents remains a concern.

Androstanols↗
PubMed1999

Pharmacokinetics and pharmacokinetic-dynamic relationship between rapacuronium (Org 9487) and its 3-desacetyl metabolite (Org 9488).

UNLABELLED: Rapacuronium (Org 9487) is a rapid-onset and short- to intermediate-acting muscle relaxant. Its 3-desacetyl metabolite, Org 9488, also exerts neuromuscular-blocking activity that may become apparent after prolonged maintenance of relaxation with rapacuronium. In this study, the pharmacokinetic behavior (n = 7) of this metabolite and the pharmacokinetic/pharmacodynamic (PK/PD) relationship of rapacuronium (n = 10) and Org 9488 (n = 7) were investigated in humans. Similar protocols were used for three study groups regarding the anesthetic technique, blood and urine sampling, and pharmacokinetic and PK/PD analyses. The time course of action was measured mechanomyographically using the adductor pollicis muscle. The median clearance of rapacuronium was 7.28 mL x kg(-1) x min(-1) x with an excretion fraction in the urine of 6.2%. The clearance (studied in two groups) of Org 9488 was 1.28 and 1.06 mL x kg(-1) x min(-1) with an excretion fraction in the urine of 51.9% and 53.5%, respectively. The median rate constant of transport between plasma and the biophase of rapacuronium (0.449 min(-1)) is markedly larger than that for Org 9488 (0.105 min(-1)). The modeled concentration in the biophase at 50% effect as a measure of potency is higher for rapacuronium (4.70 microg/mL) than for Org 9488 (1.83 microg/mL). The lower clearance of the metabolite will gradually prolong the time course of the neuromuscular blockade during maintenance with rapacuronium. IMPLICATIONS: We investigated the concentration-time-effect relationship of the relaxant rapacuronium and the contribution of its metabolite. Clearance, rate constant of transport between plasma and the biophase, and modeled concentration in the biophase at 50% effect of rapacuronium are consistent with its rapid onset and short to intermediate duration. The lower clearance of the metabolite will gradually prolong the time course of the neuromuscular blockade during maintenance with rapacuronium.

Adult↗