ABSTRACT
BACKGROUND: The motivation for this study was the current difficulty in estimating the total age-related MAC for a patient in a clinical setting. METHODS: Age-related iso-MAC charts for isoflurane, sevoflurane and desflurane were developed for the clinically useful MAC range (0.6-1.6), age range 5-95 yr, and put in a convenient form for use by practising anaesthetists. The charts are based on Mapleson's meta-analysis (1996) of the available MAC data and can be used to allow for the contribution of nitrous oxide to the total MAC. RESULTS: The charts indicate the influence of age on anaesthetic requirements, showing, for example, that a total MAC of 1.2 using isoflurane and nitrous oxide 67% in oxygen requires an end-expired isoflurane concentration of only 0.25% in a patient of 95 yr vs 1% in a 5-yr-old patient. Colleagues found the charts to be helpful and simple to use clinically. CONCLUSIONS: The iso-MAC charts show clearly how patient age can be used to guide the choice of end-expired agent concentration. They also allow a consistent total MAC to be maintained when changing the inspired nitrous oxide concentration, thereby reducing the chance of inadvertent awareness, particularly at the extremes of age.
Subject(s)
Aging/metabolism , Algorithms , Anesthetics, Inhalation/pharmacokinetics , Isoflurane/analogs & derivatives , Pulmonary Alveoli/metabolism , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Anesthetics, Inhalation/administration & dosage , Child , Child, Preschool , Desflurane , Drug Administration Schedule , Humans , Isoflurane/administration & dosage , Isoflurane/pharmacokinetics , Methyl Ethers/administration & dosage , Methyl Ethers/pharmacokinetics , Middle Aged , Reference Values , SevofluraneABSTRACT
Airway fires are an uncommon but real and devastating complication of tracheostomy. One such fire in a 31-year-old man is described. Surgical fires are discussed, and 15 reported cases of tracheostomy fire are reviewed. A tracheostomy protocol, adopted by our department and designed to avoid this life-threatening complication, is described. Surgeons and anaesthetists involved in tracheostomy must understand the fire hazard and how to avoid it.
Subject(s)
Electrocoagulation/adverse effects , Fires/prevention & control , Tracheostomy/adverse effects , Adult , Anesthesia, General/methods , Hemostasis, Surgical/adverse effects , Humans , Male , Oxygen/adverse effectsABSTRACT
Visual latency difference was determined directly in normal volunteers, using the rotating Pulfrich technique described by Nickalls [Vision Research, 26, 367-372 (1986)]. Subjects fixated a black vertical rod rotating clockwise on a horizontal turntable turning with constant angular velocity (16.6,33.3 or 44.7 revs/min) with a neutral density filter (OD 0.7 or 1.5) in front of the right eye. For all subjects the latency difference associated with the 1.5 OD filter was significantly greater (P < 0.001) with the rod rotating at 16.6 rev/min than at 33.3 revs/min. The existence of an inverse relationship between latency difference and angular velocity is hypothesized.
Subject(s)
Motion Perception/physiology , Optical Illusions/physiology , Adult , Filtration , Humans , Middle Aged , Optics and Photonics , Rotation , Time Factors , Vision, BinocularABSTRACT
Three complications of the use of narrow bore nasogastric feeding tubes are described. Clinical tests to determine correct placement are noted to be unreliable and the importance of radiological confirmation is stressed. A number of suggestions are made for safe use of these tubes.
Subject(s)
Enteral Nutrition/adverse effects , Intubation, Gastrointestinal/adverse effects , Adult , Aged , Female , Humans , Lung/diagnostic imaging , Male , Middle Aged , Pleural Effusion/etiology , Pneumothorax/etiology , Radiography , Stomach/diagnostic imagingABSTRACT
A new percutaneous infraclavicular approach for cannulating the axillary vein is described. The technique was devised using surface landmarks established by cadaver dissection. This is a relatively safe procedure with no risk of pneumothorax, provided that the tip of the needle remains inferior to the clavicle.
Subject(s)
Axillary Vein , Catheterization/methods , Axillary Vein/anatomy & histology , Clavicle , Humans , Shoulder/anatomy & histologySubject(s)
Resuscitation/methods , Acquired Immunodeficiency Syndrome/prevention & control , First Aid , Humans , Masks , MouthABSTRACT
A rotating Pulfrich effect is described and analysed in relation to the Fertsch-Pulfrich latency difference theory. Although some of the predictions conflicted with observations described by Pulfrich [Naturwissenschaften 10, 553-564 (1922)], they were confirmed by experiment, and led to a simple and sensitive method of determining visual latency differences.
Subject(s)
Illusions/physiology , Motion Perception/physiology , Optical Illusions/physiology , Fixation, Ocular , Humans , Methods , Models, Neurological , RotationABSTRACT
This paper describes an experiment performed by J. Pal of Vienna in 1900, which showed that physostigmine reverses the neuromuscular blocking properties of curare. Pal's original article is translated from the German.
