REPORT ON "TRENCH FOOT."

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1 635 REPORT ON "TRENCH FOOT." By CAPTAIN W. WALLER. Royal Army Medical Corps. AND LIEUTENANT E. K. RIDEAL (Unattached). PROVISIONAL DEFINITION OF THE CAUSES OF "TRENCH FOOT." OUR only first-hand clinical data are derived from a questionnaire of twelve cases of recovering "trench foot" seen in the Hampstead Hospital two or three weeks after the onset. The symptoms appear to be fairly constant and we have grouped them provisionally as follows: (1) Early symptoms mainly due to circulatory disturbance; these are swelling, numbness and pain. (2) Symptoms, outlasting the early symptoms, chiefly nervous in character, and mainly due to prolonged action of water on the skin; these are pain, parresthesia, blunting of sensation, lowering of excitability of the " motor points" on the leg to faradism, and contracture of the toes or ankle seen in the more severe cases. The early symptoms are said to be similar to those of frost-bite. Frost-bite, however, proceeds either towards necrosis or recovery in a comparatively short time, whereas the condition we have to deal with lasts for a month or longer. We assume, therefore, that water itself is an important cause of "trench foot," because of its action on the skin, apart from its cooling action. It is said that the condition has occurred in cases where water has been excluded, and these cases are attributed to the action of sweat in an unventilated boot. All the cases we questioned either had no trench boots, or if they had, their feet were thoroughly wet when they changed from their marching boots into the trench hoot. Moreover, the level of the water came above the top of the trench boot. " Trench foot," therefore, may provisionally be defined as a condition due to prolonged action of water on the skin combined with circulatory disturbance due to cold and inaction. Our work has been confined to a study of the action of water and the means of prevention. Action of Water on the Foot. (1) Physical Considerations.-Water is an abnormal environment for the skin. Theoretically, there are three actions of the water: (1) Loss of heat due to increase of conductivity and thermal

2 636 Report on "Trench Foot" capacity of the surrounding medium; (2) effusion of salts from the skin; (3) infusion of water into the skin. A normal skin can, of course, resist these actions, but when the exposure is prolonged and the circulation is diminished the osmotic action may become important. This is proved by experience and by the experiments to be described. Fishermen and otter-hunters find that after several hours' contact with cold water there may be some pain, tenderness, and even swelling of the feet, lasting perhaps a day or two. Workers in paper manufactories, who have to stand for a day at a time in several inches of warm water and paper pulp, have similar symptoms. These are not entirely due to circulatory disturbance. (2) Experimental Data.-In order to study the action of water on our own feet, we have worn ordinary" gum boots" for five to twelve hours, the boots being filled to the same level with water and salt water on either side. We find that ordinary tap-water has a more marked effect in a given time than four per cent seasalt solution. There have been three subjects of the experiment, and in each case the procedure was the same. The boot on one side was filled to a level of about four inches above the ankle with tap-water, and the other boot was filled to the same level with the artificial sea-water. The subject proceeded with his ordinary occupations during the day, and the feet were examined by unprejudiced observers in the evening. One of the subjects showed a marked contrast between the two feet, one of them showed a definite but less marked contrast, and the third showed hardly any difference. The following is a resume of the experiments :- (1) Subject R. H. G.-Eight hours'immersion during the day. Ordinary activity and a walk of one mile. Left foot in tap-water: Whiter, more wrinkled and more sodden than right, also less sensitive to touch alltd slightly colder to objective. Right foot almost normal, objective effect passed off in about half an hour. Three hours later, after a half-mile walk, cramp was felt at the base of the left toes. (2) Subject W. W. W.-Duration five hours. Left foot in tapwater. The feet were examined by observers who were ignorant of the purpose of the experiment. The left foot was described as being paler and more sodden than the right foot. The right foot appeared more normal. The difference passed off in half an hour. There was no subjective change. (3) Subject W. W. W.-Duration eight hours. Right foot in tap-water. Similar changes were described in the right foot. No subjective change.

W. Waller and E. K. Rideal 637 (4) Subject E. K. R-Duration eight hours. Left foot in tapwater. The difference between the feet was too slight to be described as definite.

3 W. Waller and E. K. Rideal 637 (4) Subject E. K. R-Duration eight hours. Left foot in tapwater. The difference between the feet was too slight to be described as definite. In these experiments the circulation was as normal as possible. The water remained in equilibrium at a temperature of 28 C. to ::100 C. and the feet never felt uncomfortably cold. With a temperature of 40 C., the contrast between the action of salt w!lter and tap-water is more marked. The difference is evidentj in the feet (W. W. W.) in about one hour, and very definite in two hours. In all these experiments the exposure was not prolonged enough to cause any lasting effect, but the difference constantly found indicates that, with prolonged exposure, the action of salt water might be slight, and that of ordinary water serious. We have made measurements of the increase of conductivity of tap-water in which the hand or the foot is soaking. This gives a measurement of the salt emission from the hand. The first measurements were taken ten minutes after immersion of the limb, so as to ensure the removal of superficial salt. At high dilutions the effect of non-electrolytes on conductivity is negligible. Assuming that the increase is due to NaCI, the chief electrolyte in the sweat, the following results were obtained :- Experiment I.-Subject W. W. W. Hand in vessels containing 1 25 litres of tap-water at 40 0 C. Samples of seventy cubic centimetres of the water were taken at twenty minutes' intervals for measurementb at 18 0 C., and each sample was then poured back into the large vessel. Decrease of resistance in two hours equals fifteen ohms, equivalent to fifteen milligrammes of salt. Experiment 2.-With the temperature at 18 0 C., the decrease of resistance measured at 18 was thirteen ohms, equals thirteen milligrammes of salt. Experiment 3.-Subject E. K. R Hand in 1 25 litres of tapwater at 40 0 C. Differences of resistance at 18 0 equals eight ohms, equivalent to eight milligrammes of salt emitted. Expet iment 4.-Subject W. W. W. Foot in three litres of tapwater at 40 C. Difference equals 16t ohms in two hours, equivalent to thirty-eight milligrammes of salt. In all these :experiments the chief difference occurs in the first hour, after which there is a slower change, and by the end of the second hour no further increase of conductivity can be measured. The effect of the water' on the hand also becomes visible in about an hour's time, and it seems probable that when the salt has

4 638 Report on "Trench Foot" stopped diffusing out from the hand the water begins to soak into the skin, producing the transient changes described above. Of the two subjects, E. K. R. shows a lower susceptibility to the effect of tap-water and also shows a lower salt emission. Protection of the Foot from Water. We are not concerned here with the various kinds of waterproof boots and socks. We have been told that "trench foot" occurs in cases where water has been excluded, and it was suggested that we should experiment with various kinds of grease in order to find one which should be impermeable to sweat, and should thus prevent the accumulation of sweat in the sock. It was suggested that sweat which has a salt concentration of, say, 0'5 per cent has the same injurious effect on cold feet as stagnant water. It would no doubt be possible to find a varnish impermeable to water in either direction-e.g., collodion-but we have only experimented with the natural fats, lard and tallow and whale oil, with spermaceti and whale oil, and with paraffin. We cannot find any constant difference in the action of lard, tallow, whale oil, paraffin, or mixtures of whale oil and tallow. They all cause a diminution of about fifty per cent of the transpiration. We may presume, therefore, that there is no marked difference in their relative permeabilities to water from outside. Owing to the extreme variability of the sweat it is difficult to get concordant results. The most constant results were obtained at 36 C. with a nearly saturated atmosphere. Several experiments were done at lp C., 40 C. and 45 C. They showed diminution of sweat by fat of the same order of magnitude. Method.-Hand and forearm enclosed in plethysmograph immersed in a water-bath, upper end of plethysmograph projecting into the air. Air, previously dried by sulphuric acid and warmed to temperature of the water-bath, was drawn at a constant rate through the plethysmograph and then through two weighed CaC1 2 tubes in series. A by-pass tube was fitted in parallel with the CaC1 2 tubes. In each case fifteen minutes were given to establish equilibrium, and then the air from the plethysmograph was cut off from the by-pass and sent through the CaCI 2 At the end of the experiment the hand was drawn out and plethysmographed, dried by the current of air, its open end being closed by a large glass stopper. For each ointment tested a control experiment was previously made on the naked hand. The average amount of sweat was three

5 W. Waller and 'E. K. Rideal 639 grammes per hour without ointment, and one and a half grammes per hour with ointment. Ointment Lard Tallow Whale oil Whale oil and tallow Lard + 4 per cent sea salt Tallow + 4 per cent sea-salt Spermaceti + whale oil (50 per cent) Percentage reduction. Average of three experiments 45 per cent 42 " 55 " 52 " 60 " 60 " 58 " All the above experiments were done at 36 C. with a flow of air of one and a half litres per minute. At the higher temperatures with same rate of air-flow the normal transpiration actually became slightly less on the same day:- Temperature 36" O. 40' 42" 45" 36 Rate of perspiration 3'41 grammos per hour 2'98 2'75 2'07 2'95 " " " " The reason for this fall is probably that at the higher temperature the air was less saturated, and consequently the sweat was evaporated in a more" economical" way at the skin surface. The diminution produced by fat was about the same at the higher temperatures. At a temperature of 11 C. an output of sweat of about one and a half grammes per hour in a saturated atmosphere was diminished by sixty-five per cent. It is impossible to compare the amounts at different temperatures owing to the difference in degree of saturation. These experiments were of short duration, i.e., fifteen minutes' preparation, fifteen minutes' test and fifteen minutes' drying after taking the hand out. With longer experiments no doubt the resistance of the ointment to water would be broken down, but our object has been to compare different ointments. Incidentally we have tried the effect of lard on the heat emission of the hand and forearm immersed in a constant-flow water calorimeter. We find that the calorie emissions varying from 150 to 300 calories per minute were not appreciably affected by smearing lard over the skin. Subjectively, however, the water felt warmer when the arm was smeared with lard, though the water temperature remained the same. This is probably due to the

6 Report on " Trench Foot" temperature gradient being less steep with the greased hand and the effective protecting layer being thicker. Salt~d Ointment.-Having found that salt water had less effect on the skin than tap-water, we have tried lard with four per cent sea-salt made up into an ointment. The figures given above show an apparent reduction of sixty per cent of transpiration compared with fifty per cent for ordinary lard. It is extremely probable that the real transpiration is not diminished but possibly slightly increased, and that the apparent decrease is due to the lowering of the vapour pressure of the sweat by the salt. The following calculation appears to confirm this hypothesis.. Percentage lowering of vapour pressure is given approximately by. the formula:- Percentage lowering = 100 X N- where n mols of salt are dissolved in N mols of water. In fifteen minutes ~: mols of water are formed, and since about five grammes of four per cent ~2. salt lard are used 58 mols of salt are present. This gives a percentage lowering of vapour tension of eight per cent, a figure which agrees with that experimentally found. We have also tried the effect of tap-water in a gum boot on the legs, one leg being smeared with lard and the other with salted lard. The difference in appearance is in this case much slighter, after eight to twelve hours, than it was with tap-water and salt water on the non-greased skin. Ignorant observers were, however, easily able to distinguish which was the more normal foot. The foot with salted lard recovered its colour quicker than the other and was slightly less wrinkled and less puffy. CONCLUSION. We suggest that a salted ointment such as salted lard would be beneficial in protecting the foot against water. The salt would further act as an antiseptic. A liberal amount of ointment would be necessary, e.g., 100 grammes for each leg with five or ten per cent salt. We assume that all other practical precautions have been taken, such as foot inspection, so as to ensure the men using the ointment, provision of dry socks with the waterproof trench boots, loosening of the puttees, etc. N.B.-Officers' spiral puttees contract five to six per cent of their length when they are soaked in water.

1 V. W CLller and E. Ii. R ideal 641 R. H. O.'s feet after eight hours'immctsion.-right foo t in six per cent sea-g:tlt solution ; left foot in tap.water. Tho water was put into the" gum boot!

7 1 V. W CLller and E. Ii. R ideal 641 R. H. O.'s feet after eight hours'immctsion.-right foo t in six per cent sea-g:tlt solution ; left foot in tap.water. Tho water was put into the" gum boot!!" at room temperature and was 29 0 C. a.t the end of the experiment.. Desc,;'pticnt of!eei.-i.joft wrinkled, whiter than normal with I'odden skin; right slightly wrinkled, normal colour. General appearance pract.ically normal. J R Army Med Corps: first published as /jramc on 1 May Downloaded from on 4 April 2019 by guest. Protected by copyright.

(fig. 3) must be at the same temperature as the water in this chamber CALORIMETRIC STUDIES OF THE EXTREMITIES

(fig. 3) must be at the same temperature as the water in this chamber CALORIMETRIC STUDIES OF THE EXTREMITIES CALORIMETRIC STUDIES OF THE EXTREMITIES II. EXPERIMENTAL APPARATUS AND PROCEDURES' By ROY KEGERREIS (Received for publication July 1, 1926) The calorimeter used in these experiments is a modification of