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New Inventions

GRAVITY-OPERATED PUMP FOR TUBE FEEDING

THE conventional gravity drip apparatus for continuoustube feeding has two disadvantages : first, a thick feedmay

" sludge " behind the regulating clip ; and second,

controlling a slow rate of flow is often difficult. Boththese factors may prevent the administration of thecorrect daily volume of feed ; and uneven administrationis a common cause of colic and diarrhoea, particularly injejunal feeding.To meet these objections many types of expensive and

complex forced-feed pumps have been devised. 12 Aftermuch experience of pumping jejunal feeds containinggastric and duodenal aspirate, a simple gravity-operated

Clamo .

apparatus has been designed which not only has theminimum of moving parts but also does not require aregulating clip or valve in the delivery system.The pump (see figure) consists of two vessels, A and B,

containing a total of 250 ml. ’mercury, mounted on aplatform which is pivoted at its midpoint. By incliningthe plane, the mercury can be made to run from onevessel to the other at a rate determined by the pressureof a brass plate on a spiral of fine rubber tubing. Latexrubber balloons within A and B contain the feed. The

1. Snyder, C. C. Plast. reconstr. Surg. 1951, 8, 73.2. Fallis, L. S., Barron, J. Bull. int. Chir. 1956, 15, 9.

arrangement of the valve C is such that if A is filled withmercury, and the balloon in B with a suitable feed, theflow of mercury into B will displace the feed at a constantrate into the patient ; at the same time the balloon in Awill be filled by the feed from the reservoir.When all the mercury has passed from A into B, the

pressure in B will fall to approximately that of theatmosphere ; the balloon in A is then full of feed and thevessel B with mercury. If the platform and the valve Care now rotated anticlockwise through 90°, A will refillwith mercury, displacing the feed from the reservoir.The complete cycle, which is illustrated, can be repeatedas often as required. At a feed rate of 1 ml. per minutethe platform is tipped every 4 hours.If a balloon should tear, mercury cannot reach the

patient because the outlet tube is carried above thelevel of the upper container.

Contamination of the feed by mercury passing acrossthe balloon has not occurred after periods of exposureof up to 11 hours.To control the rate of rotation of the platform, and

thus to prevent damage to the vessels A and B, a modifiedpiston from a Potter-Buckey X-ray screen is mountedbetween the platform and the base so that the assemblycan be tipped only slowly.

Department of Surgery,University of Edinburgh

D. C. SIMPSONB.SC., PH.D. Edin.

External Staff,Medical Research Council

H. A. F. DUDLEYM.B. Edin., F.R.C.S.E.

A RESUSCITATION TABLE FOR THE NEWBORN

RESUSCITATION of the newborn after anaesthesia forlabour or csesarean section is becoming more and more

of the anaesthetist.If this delicateprocedure is to becarried out effici-ently, the tiny pa-tient must be inthe correct posi-tion, at the rightheight for theoperator, and withthe head fixed sothat suction andmanual ventila-tion can be quicklyand atraumatic-ally applied.Many tables andpieces of appara-tus have beendesigned for thispurpose, butmost have dis-advantages.The table illus-

trated here (seefigure) is of a con-venient height forgeneral use withthe anaesthetiststanding ; it is

equally satisfactory for laryngoscopy when he is sittingbefore it. Laryngoscopy is facilitated by fixing thebaby’s head in the hole in the mattress-a mostimportant factor since an anoxic child is always wellrelaxed and, owing to the presence of amniotic fluid,very slippery. The hole is oval and measures 11 X9 cm. Fixation by this method is good enough to preventa healthy baby from rolling off the table even whenstruggling and kicking.The top of the table is covered by a 5 cm. thick mattress

made of sponge nylon, in which the hole for the child’shead is cut. It is also fixed in a 10° Trendelenburgslope, which can be altered, but for most cases 10° issatisfactory, provided efficient suction is available.The table is equipped with an oxygen cylinder which

has both a suction unit and a flowmeter attached. Thesuction is effective for both pharyngeal and trachealwork, and the flowmeter is connected to a bag and maskof a special light-weight type designed for babies.1The tube from the flowmeter to the bag incorporates asafety device in the form of a blow-off valve or water-seal set at a pressure of 15-20 cm. of water. This preventsany excessive pressure from reaching the baby whenartificial respiration is being applied with the bag andmask. -

A clock on the table enables an accurate check to bemade of the time which passes before normal respirationstarts, and draws attention to the need to avoid delayin suction from the bronchial tree or in ventilation.

Other equipment includes a water jug for clearingthe suction catheter and a drawer beneath the table

1. Secher, O., Nyrop, M. Anesthesiology, 1955, 16, 808