CURRENT LITERATURE

Abstracts

Effect of Short-term Smoking Halt on Carboxyhemoglobin Levels and P, Values. Kambam JR, Chen LH, Hyman SA. Anesth Analg 65: 1186, 1986

Cigarette smoking is associated with increased blood levels of carboxyhemoglobin leading to a leftward shift of the oxyhemoglobin dissociation curve. Fifteen otherwise healthy smokers were studied to investigate the effect of a 1Zhour cessation of smoking on carboxyhemoglobin levels and on the oxyhemoglobin dissociation curve. Blood carboxyhemoglobin concentration and percent he- moglobin saturation was determined for each subject. A two-point saturation curve was constructed and from this the P,, was determined. The 15 participants were then asked to cease smoking for 12 hours after which the car- boxyhemoglobin concentration and P,,, were again deter- mined; After cessation of smoking, carboxyhemoglobin levies decreased from 6.55 2 0.40% to 1.06 + 0.16% and the P,, increased from 22.92 ? 0.25 mm Hg to 26.41 ? 0.14 mm Hg (normal, 27 mm Hg). Carbon monoxide from cigarette smoke causes a leftward shift of the oxyhemo- globin dissociation curve by a direct effect and also by re- ducing.the amount of erythrocyte 2, 3 DPG. The authors concluded that cessation of smoking for as little as 12 hours preoperatively is enough to nearly normalize the P 50. The authors also suggested that smokers cease smoking for at least 12 hours prior to donaung blood as bank blood collected from smokers has significant car- boxyhemoglobin levels.- S. J. MCKENNA

Reprint requests to Dr. Kambam: Department of Anesthesia, Vanderbilt University Hospital, Nashville, TN 37232.

Histological Changes in Temporomandibular Joints from Elderly Individuals. Akerman S, Kopp S, Rohlin M. Acta Odontol Stand 44:23 1, 1986

A study was undertaken to investigate the microscopic appearance of the temporomandibular joint (TMJ) in el- derly individuals. Autopsy specimens from 21 individuals (13 men, eight women) were prepared for microscopic ex- amination. Particular attention was paid to disc form and position, and structural changes in the articulating sur- faces and evidence of inflammation. Most discs were normally positioned. Anterior displacement was found in 11 joints. The form of the disc varied greatly, but 11 discs were concave and one was convex through the entire joint; no disc was of even thickness through the entire joint. Anterior displacement was positively correlated with a convex disc form especially in the lateral and cen- tral disc. Most normally positioned and three displaced discs were concave. In some of the joints with disc dis- placement, the posterior attachment was thin and elon- gated. Most of the joints showed no structural changes. In one-sixth of the joints, there was disc perforation. The perforation was localized to the posterior attachment in five joints and to the central disc in one joint. There was a positive correlation between anterior displacement and perforation of the posterior attachment. Four of the five joints with both anterior displacement and perforation showed marked structural changes in the condyle and temporal component of the joint. Structural changes con- sisted of increased thickness of the soft tissue articular lining of the eminence and condyle with associated bone resorption. There was no correlation between anterior

displacement and these structural changes. No cellular signs of inflammation could be found in any of the joints. The authors concluded that in the elderly anterior disc displacement and structural changes such as disc perfora- tion are common. Anterior disc displacement is fre- quently associated with a convex disc form and perfora- tion of the posterior attachment.-S. J. MCKENNA

Reprint requests to Dr. Akerman: Departments of Stomatog- nathic Physiology Oral Radiology, School of Dentistry, Univer- sity of Lund, Malmo. Sweden.

Densities in Dependent Lung Regions During Anesthesia: Atelectasis or Fluid Accumulation? Strandberg A, Heden- stierna G, Tokics L, et al. Acta Anaesth Stand 30:256, 1986

In previous studies these authors demonstrated in- trathoracic densities in dependent lung regions by means of transverse computed tomography (CT scanning) within five minutes of induction of general anesthesia. This study was designed to differentiate between com- pression atelectasis and interstitial edema as to the eti- ology of these densities. Six unpremeditated patients free from cardiopulmonary disease were anesthetized with barbiturate induction, given muscle relaxant, intubated, and maintained on an inhalation agent in preparation for abdominal surgery. Four patients were then given IV contrast medium. The remaining two patients were in- jected with contrast into the pleural space and studied postoperatively. CR exposures were made at nine-second intervals and attenuation determinations made for normal lung, lung densities, and aorta. Intravenous contrast during anesthesia demonstrated increased, followed by decreased, attenuation in the densities similar to that of the pulmonary vessels and a more constant increase in the aorta. The normal lung was without change. Intra- pleural injection of contrast showed the densities to be located entirely within the lung parenchyma. The authors suggest that the densities represent a capillary-rich net- work within the lung secondary to poor aeration. This supports the hypothesis that dependent lung compression atelectasis occurs on induction of general anesthesia rather than interstitial edema.-R. MACK, JR.

Reprint requests to Dr. Standberg: Department of Surgery, Hud- dinge University Hospital, S-141 86 Huddinge, Sweden.

Glycopyrrolate During Ketamine/Diazepam Anesthesia. Mogensen F, Muller D, Valentin N. Acta Anaesth Stand 30:332, 1986

A group of 30 surgical patients above the age of 50 years undergoing alloplastic hip or knee surgery were prospectively studied to compare the effect of glycopyr- relate and atropine before, during, and after IV infusion anesthesia with ketamine and diazepam. The protocol consisted of premeditation with oral diazepam and IM atropine or glycopyrrolate given in a randomized se- quence using a double-blind technique. Anesthetic induc- tion was accomplished with IV diazepam and a ketamine and diazepam infusion. Neuromuscular blockade was maintained with gallamine. A second dose of test drug was given with neostigmine for reversal of neuromuscular blockade. The two drugs were equally effective in re-

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