Journal of clinical monitoring and computing
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J Clin Monit Comput · Jul 1999
Nonlinear model-based predictive control of non-depolarizing muscle relaxants using neural networks.
Neuromuscular blockade can be relatively easily measured in the clinical setting. Consequently, closed-loop control can be exercised by measuring the neuromuscular activity, calculating the dose of drug necessary to achieve a predefined degree of neuromuscular blockade and finally directing an infusion pump. Recently introduced short-acting blocking agents like mivacurium provide benefits for the clinical routine due to a small onset time and half life. ⋯ In a clinical study the EMG module within a Datex AS/3 monitor was used to measure the blockade and a Grasepy 3500 infusion pump for i.v. administration of mivacurium to 35 patients (ASA I-III). The performance of the novel system (mean of the T1 error: -0.32 +/- 1.7) compares favourably with closed-loop controllers demonstrated in the past. These promising results and the easy adaption to other blocking agents encourage to apply this technology even for delivering hypnotic drugs.
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J Clin Monit Comput · Jul 1999
Increase in twitch force of the adductor pollicis muscle with stabilized preload at constant thumb abduction before and after administration of muscle relaxant.
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. ⋯ 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.
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J Clin Monit Comput · May 1999
Optimal sequencing of urgent surgical cases. Scheduling cases using operating room information systems.
Optimal sequencing of urgent cases (i.e., selecting which urgent case should be performed first and which second) may enhance patient safety, increase patient satisfaction with timeliness of surgery, and minimize surgeons' complaints. Before determining the optimal sequence of urgent cases, an operating room (OR) suite must identify the primary scheduling objective to be satisfied when prioritizing pending urgent cases. ⋯ We provide mathematical structure which can be used to program a computerized surgical services information system to assist in optimizing the sequence of urgent cases. We use an example to illustrate that the optimal sequence varies depending on the scheduling objective chosen.
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J Clin Monit Comput · May 1999
Amount of air infused to patient increases as fluid flow rates decrease when using the Hotline HL-90 fluid warmer.
The intraoperative use of fluid warming devices has been recommended to avoid perioperative hypothermia and related adverse outcomes. To evaluate whether these devices might introduce risks of their own, we measured the volume of air escaping from a warmed intravenous solution that might be delivered to a patient. ⋯ We conclude that the use of the Hotline fluid warmer can result in infusion of air into the patient, introducing possible risk of air embolism.
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J Clin Monit Comput · May 1999
Comparative StudyTranscranial Doppler monitoring compared with invasive monitoring of intracranial pressure during acute intracranial hypertension.
To determine whether a simple transcanial Doppler waveform variable-pulsatility difference (systolic - diastolic blood flow velocity) can serve as a measure of critical changes in cerebral perfusion. ⋯ In pigs with induced diffuse intracranial hypertension, noninvasive transcranial Doppler waveform monitoring of pulsatility difference can identify increased cerebral oxygen extraction and dangerously decreased cerebral perfusion pressure.