Journal of clinical monitoring
-
We developed a two-compartment model to simulate neuromuscular function and heart rate following the administration of four nondepolarizing neuromuscular blocking agents (atracurium, vecuronium, pancuronium, and d-tubocurarine), three neuromuscular block reversal agents (edrophonium, neostigmine, and pyridostigmine), and two anticholinergic agents (atropine and glycopyrrolate). Twitch depression, train-of-four ratio, and heart rate were modeled during fentanyl, halothane, enflurane, or isoflurane anesthesia, optionally supplemented with nitrous oxide. Simulation results, compared with published values for each drug, fell within the clinical accuracy range (onset time 6.1 +/- 3.9% [mean +/- SEM]; duration, 1.7 +/- 3.5%, 50% effective dose, 0.5 +/- 5.7%; and 95% effective dose, 2.1 +/- 1.1%). ⋯ When inhalational agents are given concomitantly, the task becomes even more difficult, since potentiation changes with anesthetic uptake. Recurarization, tachycardia, or bradycardia may be seen with the simulation if an improper drug regimen is followed. Concurrent simulation of two identical patients allows comparison of different modes of administration, choice of anesthetic agents, and drug doses.
-
The pulse oximeter is commonly used in the operating room. We evaluated the use of a pulse oximeter to monitor systolic blood pressure in 20 healthy volunteers and 42 anesthetized patients. ⋯ The best correlation was found with Doppler ultrasound (r = 0.996) and the worst with arterial cannulation (r = 0.880). We conclude that this method can be used intraoperatively to measure systolic blood pressure.
-
An alternative method is described for measurement of central venous pressure by insertion of a right atrial catheter with a connection to a fluid-column manometer. With this method, the central venous pressure can be monitored by visual inspection of the manometer column; the stopcock does not need turning; the manometer column does not need refilling; and the catheter is always being flushed, eliminating the risk of clotting.