Comparison of train-of-four ratios measured with Datex-Ohmeda's M-NMT MechanoSensor™ and M-NMT ElectroSensor™.

Neuromuscular blockade is usually monitored using train-of-four (TOF) stimulation pattern. A TOF ratio of higher than 90 % is recommended to reduce the risk of adverse effects after anaesthesia. TOF ratio 90 % is used in clinical practice with all different neuromuscular monitors. Kinemyography (KMG) is one commercialized method to obtain numerical TOF values. We compared the KMG data obtained with Datex M-NMT MechanoSensor™ module, to the EMG data collected with Datex ElectroSensor™, during clinical anaesthesia. Ipsilateral comparisons of the sensors were performed in 20 female patients during clinical procedures in propofol-remifentanil anaesthesia. After initial bolus dose of rocuronium (0.6 mg/kg), the spontaneous recovery of TOF ratio and T1 % were monitored. KMG gave higher TOF values than EMG. The difference was significant at KMG TOF values of 40 % or higher. After anaesthetic induction, but before administration of rocuronium, both TOF sensor values drifted from the TOF value of 1.0, showing either significant spontaneous fade (T1 > T4) or tendency of reverse fade (T1 < T4). KMG overestimates the recovery from neuromuscular blockade when compared with EMG. KMG and EMG cannot be used interchangeably, and TOF ratio 90 % cannot be considered as adequate level of recovery with all monitoring devices.

Imaging requirements for medical applications of additive manufacturing.

Additive manufacturing (AM), formerly known as rapid prototyping, is steadily shifting its focus from industrial prototyping to medical applications as AM processes, bioadaptive materials, and medical imaging technologies develop, and the benefits of the techniques gain wider knowledge among clinicians. This article gives an overview of the main requirements for medical imaging affected by needs of AM, as well as provides a brief literature review from existing clinical cases concentrating especially on the kind of radiology they required. As an example application, a pair of CT images of the facial skull base was turned into 3D models in order to illustrate the significance of suitable imaging parameters. Additionally, the model was printed into a preoperative medical model with a popular AM device. Successful clinical cases of AM are recognized to rely heavily on efficient collaboration between various disciplines - notably operating surgeons, radiologists, and engineers. The single main requirement separating tangible model creation from traditional imaging objectives such as diagnostics and preoperative planning is the increased need for anatomical accuracy in all three spatial dimensions, but depending on the application, other specific requirements may be present as well. This article essentially intends to narrow the potential communication gap between radiologists and engineers who work with projects involving AM by showcasing the overlap between the two disciplines.

[Medical applications of rapid prototyping--three-dimensional bodies for planning and implementation of treatment and for tissue replacement]. / Teollisen pikavalmistuksen lääketieteelliset sovellukset.

The possibilities of medical applications of rapid prototyping are continuously expanding and developing. In current applications, five main groups are distinguished: (1) preoperative planning, surgical training and teaching, (2) inert implants, (3) surgical instruments and special equipment associated with the operations, (4) postoperative guides, long-term supports and aids and (5) artificial tissue. The first four of these are already in general use, whereas the last one is still under investigation.

Pharmacokinetic-pharmacodynamic relationship of dobutamine and heart rate, stroke volume and cardiac output in healthy volunteers.

BACKGROUND AND OBJECTIVE: Dobutamine causes an increase in cardiac output (CO) by augmenting stroke volume (SV) through enhanced left ventricular contractility and by decreasing systemic vascular resistance. However, in some patients, the dominant mechanism by which dobutamine improves left ventricular performance is an increase in the subject's heart rate (HR). We therefore decided to evaluate the pharmacokinetic-pharmacodynamic relationship of dobutamine plasma concentrations and heart rate, SV and CO in healthy volunteers. METHODS: We enrolled 23 subjects who received dobutamine at a dose of 2.5, 5 and 10 microg/kg/min for three consecutive periods of 60 minutes each. Dobutamine plasma concentrations were determined from 22 blood samples drawn during each study session. Echocardiography was used to measure CO before administration of dobutamine and once during each infusion period. RESULTS: There was a clear linear relationship between dobutamine plasma concentrations and CO (r(2) = 0.628; p < 0.001). In most subjects, HR remained stable at dobutamine plasma concentrations produced by the lowest infusion rate but increased markedly thereafter so that overall there was a linear relationship between dobutamine plasma concentrations and HR (r(2) = 0.540; p < 0.001). However, SV increased significantly at the dobutamine plasma concentrations produced by the lowest infusion rate but remained mostly stable or even decreased thereafter. Although clinically slight, the overall increase in SV was statistically significant (r(2) = 0.062; p < 0.05). CONCLUSION: Low plasma concentrations of dobutamine resulted in an increase in CO almost solely due to improved left ventricular contractility. However, at higher plasma concentrations of dobutamine, SV remained stable or even decreased, and the linear increase in CO was entirely based on increased HR.

Intravenous hypertonic saline to reduce intraocular pressure.

PURPOSE: To quantitate the effect of intravenous hypertonic saline (IVHTS) injection on elevated intraocular pressure (IOP). METHODS: Nineteen patients (median age, 65 years; range, 41-84 years) with glaucoma and an IOP 30 mmHg or higher were recruited. A bolus of IVHTS (sodium chloride concentration 23.4%) was injected in an antecubital vein over 10-20 seconds. The IOP and systolic and diastolic blood pressure (BP) were measured frequently for 2 hr. The dosage was 0.5 mmol/kg sodium in 11 patients (Group 1) and 1.0 mmol/kg in eight patients (Group 2). RESULTS: In both groups, a median absolute IOP reduction of 7 mmHg was achieved in 5 min. The maximum median reduction was 7 mmHg (range, 4-16) and 9 mmHg (range, 3-14) at 5 and 16 min after IVHTS in Group 1 and 2, respectively, at which point the median IOP had reduced from 38 and 35 mmHg to 31 and 27 mmHg (p < 0.001), respectively. In both groups, the IOP remained 7 mmHg reduced 2 hr after IVHTS. Systolic BP increased a median of 14.5 mmHg at 3 min and was comparable with baseline after 6 min. CONCLUSION: Intravenous hypertonic saline solution reduces IOP moderately within minutes for up to 2 hr.

Intravitreal triamcinolone acetonide as an adjuvant therapy to panretinal photocoagulation for proliferative retinopathy with high risk characteristics in type 1 diabetes: case report with 22 weeks follow-up.

PURPOSE: To describe a new treatment protocol to deliver panretinal photocoagulation that may avoid further deterioration of vision in patients with type 1 diabetes mellitus with proliferative retinopathy with high risk characteristics for severe visual loss and cystoid macular oedema. METHODS: Fundus photography, measurement of foveal thickness with optical coherence tomography and best corrected visual acuity (BCVA) determined by Snellen and ETDRS charts were measured before and after treatment in a 28-year-old man. RESULTS: Over 9 weeks, BCVA improved from 0.05 to 0.25 and the number of letters read at 2 metres from four to 39 after panretinal photocoagulation and adjuvant intravitreal triamcinolone injection under intraconal anaesthesia. Foveal thickness decreased from 691 microm to 239 microm and cysts disappeared by 15 weeks. By 22 weeks, foveal thickness had increased to 282 microm and small cysts had reappeared, but BCVA remained at 0.2 and the number of letters read at 30. CONCLUSION: Proliferative retinopathy regressed, cystoid macular oedema disappeared and vision improved after panretinal photocoagulation and adjuvant intravitreal triamcinolone acetonide injection under intraconal anaesthesia. This represents a feasible option in cases where pain during laser treatment and impairment of vision afterwards due to cystoid macular oedema result in poor compliance with standard laser treatment under topical anaesthesia.

A rapid increase in the inspired concentration of desflurane is not associated with epileptiform encephalogram.

UNLABELLED: The large inspired concentration of sevoflurane (S) during mask induction of anesthesia can induce epileptiform electroencephalogram (EEG) associated with tachycardia. Tachycardia is also seen when the concentration of desflurane (D) is abruptly increased. It is not known whether this is associated with epileptiform EEG similar to S. We studied EEG and heart rate (HR) during rapidly increased concentrations of S or D in 31 females during the postintubation period of anesthesia. Anesthesia was induced with propofol and remifentanil, and the tracheas were intubated. Patients were randomized to receive either S or D in nitrous oxide-oxygen mixture after intubation, at a small dose first. After 10 min, S or D vaporizer was advanced to the highest reading of the vaporizer (7% for S, 18% for D) for 5 min. HR and EEG were recorded. Epileptiform EEG activity was recorded in eight of 15 patients in group S and in none in group D (P < 0.05). HR increased in both groups. In group S, HR increased gradually and the highest HR value was 84 bpm at 5 min after the increase in sevoflurane concentration. In group D, HR increased to 93 bpm 2 min after the increase in desflurane concentration (no significant difference, S versus D). A rapid increase in the concentration of S frequently induces epileptiform EEG during normoventilation. Tachycardia during increasing concentrations of D is not associated with epileptiform EEG. IMPLICATIONS: A rapid increase in the concentration of sevoflurane induces epileptiform encephalogram (EEG) with tachycardia. A rapid increase in the concentration of desflurane also induces tachycardia but is not associated with epileptiform EEG.

Long-term effects of and physiological responses to nitrous oxide gas treatment during alcohol withdrawal: a double-blind, placebo-controlled trial.

BACKGROUND: Nitrous oxide gas (N2O) has been proposed to be effective in the treatment of the alcohol withdrawal syndrome (AWS). This has not been proved, however, in studies performed according to good clinical practice guidelines. Moreover, previous studies have not measured end tidal N2O concentrations or physiologic responses during N2O treatment. We have recently reported that in a double-blind, randomized, controlled setting, N2O was not superior to placebo in relieving AWS symptoms. In this previous study, we did not find significant differences between the treatments either in the Clinical Institute Withdrawal Assessment of Alcohol scores or in the total use of benzodiazepines (diazepam and temazepam). The aim of the present study was to characterize other effects and side effects of the N2O treatment using several objective measures and to study the possible long-term efficacy of the treatment. METHODS: A total of 105 inpatients who had AWS and were admitted to the A-Clinic detoxification center were included in the study. The subjects were randomly assigned to one of the following three treatments: (1) N2O/oxygen (from 30 to 70% in oxygen), (2) air/oxygen (30%/70%), and (3) medical (normal) air. During the single 45-min treatment period, end-tidal N2O, carbon dioxide, and oxygen concentrations were measured. The physiologic responses were studied by measuring heart rate, blood pressure, pulse oximetric saturation, frontal muscle electromyographic activity, and plethysmographic pulse amplitude. Long-term effects were studied by measuring craving with the Obsessive-Compulsive Drinking Scale; severity of dependency with Severity of Alcohol Dependence Data; and liver enzymes with aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltransferase 3 and 6 months after the treatment. RESULTS: Patients in the N2O group demonstrated significantly higher facial muscle electromyographic activity and higher pulse amplitude than the air-treated subjects. Self-reported side effects between the gas treatments, however, did not differ between the groups. Regarding long-term effects of the treatments, there were no differences between the groups. CONCLUSIONS: Contrary to previously published data, N2O treatment did not decrease craving or liver enzymes during the 6-month follow-up. At the concentration used, N2O treatment produced signs of arousal instead of strong sedation.

Monitoring Seizure Duration During Electroconvulsive Therapy.

Three alternative monitoring methods for assessing the duration of seizures during electroconvulsive therapy were studied. The mean integrated amplitude of the electroencephalogram, facial muscle electromyogram, and "cuff method" were compared with the reference single-channel unprocessed electroencephalogram in 78 sessions with 17 patients. The measures of seizure duration differed significantly (p < 0.001). The mean integrated electroence phalographic amplitude differences were small and an artifact of the sampling procedure. Larger, but clinically unimportant, discrepancies were obtained with the facial electromyogram amplitude. In contrast, there were marked differences between the electroencephalogram and the "cuff method," which suggest that the latter technique may be of limited usefulness.