45

THE NEWBORN INFANT’S OXYGEN-SUPPLY

R. E. BONHAM CARTERMAVIS GUNTHER.

Department of Child Welfare,University College Hospital,

London.

SIR,-While we are grateful for your leader of June 29we would like, for the sake of completeness, to re-empha-sise the evidence in favour of a high cardiac output(stroke volume) being a factor in the erection of pul-monary capillaries at or immediately after birth. Thereis the cine-radiographic film of Lind and Wegelius showingthe startling diminution in the heart size during thefirst 2 or 3 breaths and the finding of high caval venouspressure in premature babies who do well with respiratorydifficulty. Clearly if a high cardiac output is normallynecessary and more necessary in asphyxia with increasedperipheral vascular resistance, a blood volume whichcan be varied by as much as 47% of the expected totalwill be a considerable factor in maintaining this cardiacoutput.

Lastly, we are not clear that hyaline membrane andall of the pulmonary syndrome of the newborn are thesame thing, for ultimately the diagnosis of hyalinemembrane is histological and some infants sufferingfrom the pulmonary syndrome live. And it should beborne in mind that a histological appearance may haveseveral causes.

THE ARCHITECTURAL FUNCTION OF THEPULMONARY CAPILLARIES

J. KEITH CARTER.Mental Hospitals’ Group Laboratory

West Park Hospital,Epsom.

SIR,-I must point out a minor inaccuracy in Dr.Bonham Carter’s article (June 22).The pulmonary circuit is not an electrical one, hence

Ohm’s law cannot be said to apply. The correct formulais due to Poiseuille for the flow of liquid through a

capillary : _

V nr4 Pt 817]

where t is the time required for the volume V of liquidof viscosity 7) to flow through the capillary of radius rand length 1, under pressure P.

It must be fascinating for the student of analogies tofind an electrical circuit used to exemplify the flow ofliauid through a tube !

TOBACCO-SMOKING AND LUNG CANCER

W. A. BALL.

SiR,—The report of the Medical Research Council ontobacco-smoking and cancer of the lung can give us anopportunity to survey our knowledge of cancer and toassa,y its value.

It is a melancholy thought that hundreds of research-workers spending hundreds of millions of money havebeen at work for well over thirty years on this problemand at the end of this period we have advanced so little,if at all. The very volume of money and effort has builtup an organised research which is no longer original. Itsvery bulk forces it through the well-worn channels.To one who has been in practice for nearly thirty years

the theory that cancer is, in its essence, a tumour causedby a carcinogen is most unsatisfactory. Carcinogens arelaboratory factors. We see in practice a large numberof cases of cancer but the cases where a carcinogenicfactor can ever be surmised, let alone proved, are nil orinfinitesimal.

Surely cancer is not primarily a tumour ; the tumouris a symptom. In practice all have seen cases with avery small tumour and very severe cancer symptoms and,on the other hand, cases with a large tumour and thevery minimal symptoms ; often we diagnose or suspectcancer before the tumour is discoverable.Two quotations from the report are of interest :

"... it- must be borne in mind that a very long period,20 years or more, may elapse between exposure to a

carcinogenic agent and the production of a tumour."And "... five substances have already been foundwhich are known to be capable in certain circumstancesof causing cancer in animals."

Thirty, forty years of work and that is the quality ofour harvest.

Let us hope that the self-interest of the tobacco tradewill separate the grain from the chaff of our researchand open up new avenues of attack.The report admits that we have not proved the

presence of a human carcinogen in tobacco-smoking.Surely we must admit that it is a possibility that subjectswith carcinoma of the lung smoke heavily because theyderive some benefit, either real or imaginary. Manypeople suffer from carcinoma of the lungs ; some are

smokers and some non-smokers ; some consider thatthey derive benefit from smoking and are claimed asheavy smokers. Surely, this is just as correct statisticallyas the conclusions of the Medical Ttese.a.T’ch f!onnf,i1.

1. Cunningham’s Text-Book of Anatomy. Edited by J. C. Brashand E. B. Jamieson. London, 1943 ; p. 645.

2. Gray’s Text-Book of Anatomy. Edited by T. B. Johnston andJ. Whillis. London, 1946 ; p. 1409.

3. Buchanan’s Manual of Anatomy. Edited by F. Wood Jones,London, 1949 ; p. 803.

4. Jamieson, E. B. A Companion to Manuals of Practical Anatomy.London, 1950 ; p. 646.

SURGERY OF CHRONIC PANCREATITIS

SIR,-In the operative treatment of chronic pancreatitis,Prof. Ian Aird (June 8) has found that " retrogradepancreaticojejunostomy

"

(implanting the body or theneck of the pancreas, after transection, into the jejunum)has been more satisfactory than " caudal pancreatico-jejunostomy " (amputating the tip of the tail of the

gland and implanting the cut end into the jejunum).In none of his cases had it been convenient to implantthe tail of the gland into the jejunum.

Professor Aird describes the tail of the pancreas as

really very short, being that part of the gland whichlies between the two layers of the lienorenal ligament.It is of some significance surgically, apart from pan-creaticojejunostomy, for operations involving the upperleft quadrant of the abdomen, in particular splenectomy,may be associated with damage to it. This may causeliberation of pancreatic ferments, with resulting fatnecrosis and a lowered resistance to infection, predispos-ing to subphrenic inflammation. The descriptions givenby different authorities of the left extremity of the pan-creas are found to vary considerably. The tail of the

pancreas is described as : an abrupt blunt ending, butsometimes elongated and narrow 1; narrow, usuallylying in contact with the inferior part of the gastricsurface of the spleen 2 ; the pointed and free left

extremity of the body 3 ; and the thickened rather thanattenuated left end of the pancreas.4

In view of these varying accounts, 38 specimens ofthe lateral end of the pancreas were recently dissectedin the Anatomy Department, Edinburgh University,through the kind interest of Prof. G. J. Romanes. Ofthese specimens, 17 were found to have a definite tail,as contrasted with the rest of the organ..

4 of these tails were triangular and tapered rapidly to apoint ; 8 were prismatic in shape with sharp or roundedborders and clearly distinct from the body of the gland onaccount of their smaller dimensions. In 2 the tail was ashort blunt tag separated from the body by a vascular groove,and in 2 a flattening in the anteroposterior plane constituteda distinct tail. In 1 case there was a bifid tail, with no vesselor other structure lying between the two portions.In 17 specimens there was no narrowing of the bodyof the pancreas appreciable enough to be termed a

" tail."

In 8 of these the body ended with a rounded contour, andin 9 the body ended abruptly as if cut off by a scalpel.