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LEAKAGE I N ANESTHETIC CIRCUITS To the Editor: The paper by Cottrell et all clearly focuses on certain areas where gas leakage occurs from the anesthesia circuit. We agree with the observations of the authors regarding the disposable rebreathing circuits. The only one we found to show minimal leaks, less than 50 ppm of N,O, a t 30 to 40 cm water pressure in the circuit 10 cm from the plastic swivel-type Y-connector was the Penlon Circuit. In a recent issue2 we described a waste gas scavenging valve which, according to our studies, is quite efficient. Different areas in the anesthetic circuit that also may be a source of pollution in the atmosphere were monitored, utilizing an Ohio Trace Gas Analyzer. Ten consecutive determinations were made at various pressures a t 10 to 25 cm from the vulnerable areas. Other areas of concern are: (1) The Ohio Scavenger Valve System, where exhaust gases are removed by suction. The outer corrugated hose, about 218 cm long, 22 mm I D (volume 700 to 800 ml) , constitutes a reservoir for the overflow of gases from the valve. Readings of over 300 ppm at 10 cm from the distal end of this reservoir hose were recorded when the reservoir bag was emptied rapidly. To eliminate this source of gas spillover the following system was devised (figure). The 218 cm of corrugated hose was replaced

lor

with a 100-cm hose (a) A T-adaptor* (b) was inserted with an inspiratory one-way valve?. (c) on the sidearm which serves as an inlet for air. A 3 to 4 L rebreathing bag (d) with a nipple at the tip is fitted on the other end of the T-adaptor. The suction tubing (el is passed through the T-adaptor, the rebreathing bag, and the nipple of the rebreathing bag (f), which fits snugly around the suction tubing. (2) A major source of pollution is leakage of gases from connectors utilized with

piped gas systems. In our experience readings were consistently higher than 300 ppm with the Schrader connectors.

S. N. Albert, MD, Chairman Alex M. Kwan, MD James W. Dadisman, Jr. Department of Anesthesiology Greater Southeast Community Hospital Washington, D. C. *T-Adaptor, Aerosol T-Adaptor #1077, Hudson Oxygen Therapy Sales Co., 2016 Seville Rd., Wadsworth, Ohio 44281 ?One-way valve obtained from the disposable T-piece with two one-way valves, Cat. #395945, OEM Med. Inc., 29 Meridian Rd., Edison, New Jersey 08817

REFERENCES 1. Cottrell JE, Chalon J, Turndorf H: Faulty anesthesia circuits: a source of environmental pollution in the operating room. Anesth Analg 56:359362, 1977 2. Albert CA, Kwan A, Kim C, et al: A waste gas scavenging valve for pediatric systems. Anesth Analg 56:291-292, 1977

LATERAL TILT I N CESAREAN SECTION To the Editor:

TO SUCTION

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Anesth Analg Vol. 56, Nov.-Dec. 1977

I refer to the excellent article entitled “A Comparison of General Anaesthesia and Lumbar Epidural Analgesia for Elective Cesarean Section,” by Francis James and his colleagues.1 The authors were kind enough to quote work from this department’ regarding a statement that there is no difference between the right and left lateral tilt position for cesarean section. This in fact was not our claim, as we did not investigate this particular aspect at the time. We have since compared the merits of

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right versus left lateral tilt at cesarean section,2 and are pleased to confirm the sentiments expressed by James et al,l namely, that a leftward tilt with the right hip supported is preferable to both mother (less hypotension) and infant (improved biochemical status).

J. W. Downing Professor of Anaesthetics University of Natal P.O. Box 17039, Congella 4013 Durban, South Africa

REFERENCES 1. James FM, Crawford JS, Hopkinson R, et al: A comparison of general anaesthesia and lumbar epidural analgesia for elective cesarean section. Anesth Analg 56:228-235, 1977

2. Downing JW, Coleman AJ, Mahomedy MC, et al: Lateral table tilt for caesarean section. Anaesthesia 29:696-703, 1974 3. Buley FUR, Downing JW, Brock-Utne JG, et al: Right versus left lateral tilt for caesarean section. Br J Anaesth (in press)

PITUITARY ADENOLYSIS To the Editor: Corssen and his colleagues’ report1 on alcohol-induced adenolysis of the pituitary gland is a major contribution to the control of cancer pain because of its success rate and relative ease and safety of implementation. However, we would like to point out that keeping the needle tip “in close proximity to, but not in direct contact with, the midline structures” will not always ensure avoidance of trauma to important structures. While the cavernous sinuses are located laterally, there occur intercavernous connections within the sella which pass anterior, posterior, and inferior to the gland.‘ Although intraoperative bleeding encountered by the authors did not have significant se-

quelae, the location of these sinuses across the midline does increase the potential for this complication. It also provides a portal of entry for venous air embolism, during both transphenoidal adenolysis and surgical hypophysectomy. We have recently reported 3 cases of entrainment of air in patients undergoing transphenoidal hypophysectomy in the semisitting position.“ In addition, even the midline approach will not guarantee “a minimum of bony resistance” since anatomical variations in the sphenoid sinus also occur.$ The sphenoidal cavity is actually absent in the concha type, seen in 3 percent of cases, and entirely filled with cancellous bone. In the presellar type, comprising 11 percent of cases, the basilar bone extends under the sella turcica to the anterior aspect of the floor in line with the tuberculum sellae, necessitating indirect location of the sellar floor fluoroscopically. Preoperative elucidation of the anatomy of the sphenoid sinus by tomography may E helpful. Philippa Newfield, MD Joseph C. Maroon, MD Maurice S. Albin, MD, MSc (Anes. Neuroanesthesia Service Department of Anesthesiology and Department of Neurosurgery, Presbyterian-University Hospital University of Pittsburgh School of Medicine Pittsburgh, Pennsylvania

REFERENCES 1. Corssen G, Holcomb MC, Moustapha I, et al: Alcohol-induced adenolysis of the pituitary gland: a new approach to control of intractable cancer pain. Anesth Analg 56:414-421, 1977 2. Renn WH, Rhoton AL: Microsurgical anatomy of the sellar region. J Neurosurg 43:288-298 3. Newfield I?, Albin MS, Chestnut J, et al: Air embolism during transphenoidal hypophysectomy. Neurosurgery (in press)

4. Hamburrrer CA. Hammer G. Noorlen G. et al: Transphenoidal hypophysectomy. Arch Otolaryngol 74:2-8, 1961