acidosis and its significance

1
30 to hospital; these, however, have been so success- fully dealt with that contagious diseases of all kinds were responsible for less loss at the time of signing of the armistice than at any other period of the war. ____ ACIDOSIS AND ITS SIGNIFICANCE. THE seventh report of the " Special Investigation Committee on Surgical Shock and Allied Condi- tions," which was appointed by the Medical Research Committee in August, 1917, deals with the con- troversial question of " acidosis." The name itself is a somewhat unfortunate one for the state which it is used to designate-namely, that in which the normal reserve of potential alkali, practically sodium bicarbonate, in the blood has become reduced below about 70 per cent. pf its proper value. It suggests that the reaction of the blood has been changed towards the acid side. This is very rarely the case. We have but to remember that, putting the matter somewhat crudely, blood is made alkaline by the sodium bicarbonate, acid by the dissolved carbon dioxide ; so that, if the former goes down, it is only necessary to reduce the latter in pro- portion in order to maintain the hydrogen-ion con- centration at its normal value. The removal of carbon dioxide is effected, as is well known, by increased activity of the respiratory centre. Since it is actual increase of hydrogen-ion concentration that is responsible for the physiological effects of acidity, as shown in Section VI. of the report, it is difficult to see how, apart from this, a reduction in the concentration of sodium bicarbonate should have such serious results as are attributed to the state of acidosis. But it has been found that not only in wound-shock, but after anaesthesia and in diabetes, the alkaline reserve is reduced, and certain observers have held the state of wound- shock to be essentially due to this factor. It is obvious that an important question of treatment is involved. If the decrease in bicarbonate is the actual cause of the state, no further treatment should be required than the administration of alkali. It was therefore necessary to subject the question to a thorough experimental and critical examination. The results of this are given in the report before us. The original report must be consulted for the methods used and details of the experiments. We must be content here with a summary of the conclusions arrived at. The first point tested was whether the reduction of the alkaline reserve in normal animals has any serious consequences. Although this was reduced by the injection of acid to a lower level than that of the most severe cases of diabetic coma reported, the cats and rabbits used showed no abnormal symptoms, except some slight dyspnoea on exertion. This conclusion is the more convincing because some members of the committee had at one time obtained shock-like symptoms by the injection of acid, but they were ultimately completely convinced that their results were not due to acidosis. The next question discussed is, " Does acidosis favour the production of shock by other agencies, such as haemorrhage, histamine, peptone, adrenalin, vaso-motor para- lysis ?" No evidence was found that there is any such effect, except perhaps that acid may exaggerate the depressant action of some anaesthetics. If, then, we are led to the conclusion that acidosis does not produce shock, either directly or indirectly, it is necessary to account for the fall of bicarbonate f reserve observed in shock. Evidence is given in the report that this is the result of defective supply of oxygen to the tissues, brought about by the slowed circulation. Details are given of experi- ments in which a low blood pressure was produced in different ways, with the result of acidosis of varying degrees of severity. The experiments of Wright and Colebrook, pub- lished in these pages,l confirm this conclusion. The next section is a valuable account of the factors controlling the reaction of the blood, show- ing the distinction that is to be made between a reduction of bicarbonate reserve and a real increase in acidity ; while the final section describes briefly the methods in use for the actual determination of either of these properties. From the practical point of view emphasis is laid on the cardinal importance of maintaining an adequate oxygen supply to the tissues. Since an increase in the acidity of the blood stimulates the respiratory centre to increased ventilation of the lungs, the production of acid in the tissues tends to correct itself in this way, so that the introduction of alkali may even be injurious. But a significant conclusion drawn from experimental evidence is that "oxidation in the tissues is far more easily rendered inadequate by defective circulation through the capillaries than by a reduction either of the oxygen-carrying power of the blood or of oxygen-tension in the inspired air." As much as 75 per cent. of the total blood volume can be removed from the circulation with- out harm, provided that it is replaced by gum- saline solution. The value of measurements of the bicarbonate reserve is that they indicate deficient circulation and the need for increasing the volume of the blood. A good supply of oxygen by the blood to the tissues is obviously of importance in restricting the spread of infection by anaerobic organisms. The question of gas gangrene is discussed in a special section, and experiments are given which show that the failure of the circulation cannot be attributed to the production of acid. MR. HENRY SANDFORD. ON Christmas Eve, at his house, Bladen, Bromley, Mr. Henry Sandford, the solicitor to this journal, died in the 86th year of his age. Nearly ninety years ago Thomas Wakley, the Founder of THE LANCET, in one of the worst of his many legal embroilments, turned to the firm, of which Mr. Henry Sandford was the senior representative at his death, for help and advice. The firm then included one of Wakley’s cousins, and from that time the same firm, now under the style of Potter, Sandford, and Kilvington, has advised the pro- prietors and editor of THE LANCET to our great benefit. ALOIS EPSTEIN. Professor A. Epstein, whose recent death in his seventieth year has escaped general notice, was not only director of the principal children’s clinic in Bohemia but had at his disposal the whole of the Prague Foundling Institute for teaching purposes. This combination accounts for the fact that his clinical teaching was so fruitful in result at home and so widely accepted over the world. Epstein’s life was, in fact, devoted to the physiology and pathology of the new-born child, and the immediate result of his medical direction of the foundling institution was a drop in mortality from almost incredible figures to 5 per cent., where it has since 1 THE LANCET, 1918, i., 763.

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Page 1: ACIDOSIS AND ITS SIGNIFICANCE

30to hospital; these, however, have been so success-fully dealt with that contagious diseases of allkinds were responsible for less loss at the time ofsigning of the armistice than at any other periodof the war.

____

ACIDOSIS AND ITS SIGNIFICANCE.

THE seventh report of the " Special InvestigationCommittee on Surgical Shock and Allied Condi-tions," which was appointed by the Medical ResearchCommittee in August, 1917, deals with the con-troversial question of

" acidosis." The name itself

is a somewhat unfortunate one for the state whichit is used to designate-namely, that in which thenormal reserve of potential alkali, practically sodiumbicarbonate, in the blood has become reduced belowabout 70 per cent. pf its proper value. It suggeststhat the reaction of the blood has been changedtowards the acid side. This is very rarely the case.We have but to remember that, putting the mattersomewhat crudely, blood is made alkaline by thesodium bicarbonate, acid by the dissolved carbondioxide ; so that, if the former goes down, itis only necessary to reduce the latter in pro-portion in order to maintain the hydrogen-ion con-centration at its normal value. The removal ofcarbon dioxide is effected, as is well known, byincreased activity of the respiratory centre. Sinceit is actual increase of hydrogen-ion concentrationthat is responsible for the physiological effects ofacidity, as shown in Section VI. of the report, it isdifficult to see how, apart from this, a reduction inthe concentration of sodium bicarbonate shouldhave such serious results as are attributed to thestate of acidosis. But it has been found that notonly in wound-shock, but after anaesthesia and indiabetes, the alkaline reserve is reduced, andcertain observers have held the state of wound-shock to be essentially due to this factor. It isobvious that an important question of treatment isinvolved. If the decrease in bicarbonate is theactual cause of the state, no further treatmentshould be required than the administration ofalkali. It was therefore necessary to subject thequestion to a thorough experimental and criticalexamination. The results of this are given in thereport before us. The original report must beconsulted for the methods used and details of the

experiments. We must be content here with asummary of the conclusions arrived at.The first point tested was whether the reduction

of the alkaline reserve in normal animals has anyserious consequences. Although this was reducedby the injection of acid to a lower level than thatof the most severe cases of diabetic coma reported,the cats and rabbits used showed no abnormalsymptoms, except some slight dyspnoea on exertion.This conclusion is the more convincing becausesome members of the committee had at one timeobtained shock-like symptoms by the injectionof acid, but they were ultimately completelyconvinced that their results were not dueto acidosis. The next question discussed is, "

Does acidosis favour the production ofshock by other agencies, such as haemorrhage,histamine, peptone, adrenalin, vaso-motor para-lysis ?" No evidence was found that there is anysuch effect, except perhaps that acid may exaggeratethe depressant action of some anaesthetics. If, then,we are led to the conclusion that acidosis does notproduce shock, either directly or indirectly, it isnecessary to account for the fall of bicarbonate freserve observed in shock. Evidence is given in

the report that this is the result of defective supplyof oxygen to the tissues, brought about by theslowed circulation. Details are given of experi-ments in which a low blood pressure was

produced in different ways, with the resultof acidosis of varying degrees of severity. The

experiments of Wright and Colebrook, pub-lished in these pages,l confirm this conclusion.The next section is a valuable account of thefactors controlling the reaction of the blood, show-ing the distinction that is to be made between areduction of bicarbonate reserve and a real increasein acidity ; while the final section describes brieflythe methods in use for the actual determination ofeither of these properties. From the practicalpoint of view emphasis is laid on the cardinalimportance of maintaining an adequate oxygensupply to the tissues. Since an increase in theacidity of the blood stimulates the respiratorycentre to increased ventilation of the lungs, theproduction of acid in the tissues tends to correctitself in this way, so that the introduction of alkalimay even be injurious. But a significant conclusiondrawn from experimental evidence is that "oxidationin the tissues is far more easily rendered inadequateby defective circulation through the capillaries thanby a reduction either of the oxygen-carrying powerof the blood or of oxygen-tension in the inspiredair." As much as 75 per cent. of the total bloodvolume can be removed from the circulation with-out harm, provided that it is replaced by gum-saline solution. The value of measurements of thebicarbonate reserve is that they indicate deficientcirculation and the need for increasing the volumeof the blood. A good supply of oxygen by the bloodto the tissues is obviously of importance in

restricting the spread of infection by anaerobicorganisms. The question of gas gangrene isdiscussed in a special section, and experiments aregiven which show that the failure of the circulationcannot be attributed to the production of acid.

MR. HENRY SANDFORD.

ON Christmas Eve, at his house, Bladen, Bromley,Mr. Henry Sandford, the solicitor to this journal,died in the 86th year of his age. Nearly ninetyyears ago Thomas Wakley, the Founder ofTHE LANCET, in one of the worst of his manylegal embroilments, turned to the firm, of whichMr. Henry Sandford was the senior representativeat his death, for help and advice. The firm thenincluded one of Wakley’s cousins, and from thattime the same firm, now under the style of Potter,Sandford, and Kilvington, has advised the pro-prietors and editor of THE LANCET to our greatbenefit.

ALOIS EPSTEIN.

Professor A. Epstein, whose recent death in hisseventieth year has escaped general notice, was notonly director of the principal children’s clinic inBohemia but had at his disposal the whole of thePrague Foundling Institute for teaching purposes.This combination accounts for the fact that hisclinical teaching was so fruitful in result at homeand so widely accepted over the world. Epstein’slife was, in fact, devoted to the physiology andpathology of the new-born child, and the immediateresult of his medical direction of the foundlinginstitution was a drop in mortality from almostincredible figures to 5 per cent., where it has since

1 THE LANCET, 1918, i., 763.