Fluid and Electrolyte Replacement for the Surgical Patient

FLUID AND ELECTROLYTE REPLACEMENT FOR THE SURGICAL PATIENT JAMBS WALKER, JR.,

M.D. *

The general concepts governing fluid exchange in the surgical patient have been discussed in a recent review article by Ravdin and Walker.l There is general agreement as to the care of the simple surgical case. However, the care of the patient with exceptionally large losses of fluid from the stomach and small bowel remains, at times, a difficult problem, and this present report is devoted largely to it. A method of handling such a case is outlined and some general principles in the management of such cases are discussed. REPORT OF A CASE

L. Me. A. was a 68 year old white ma:[l admitted following a four day history of generalized abdominal pain, distention, nausea and vomiting. Upon admission he was found to markedly dehydrated, with evidence of small bowel obstruction. His blood volume was two liters below normal, with an hematocrit reading of 70 per cent cells. Determination of "thiocyanate available fluid" showed a deficit of about. 4 liters. His plasma chloride level was 94 milliequivalents per liter. Prior to operation he was given a liter of blood, 650 ml. of plasma, 1100 inl. of physiological saline solution and 1100 ml. of 5 per cent glucose in water by intravenous route. At operation he was found to have an appendiceal abscess obstructing the blood supply to about 3 feet of terminal ileum with resulting gangrene of this portion of the small bowel. The nonviable ileum was resected, a double barrelled ileostomy being formed. The appendiceal abscess was drained and the appendix removed. On the third postoperative day, the ile::lstomy began to drain 3 to 4 liters and an additional 1500 ml. were removed from the stomach through a Levine tube. Figure 614 illustrates the amounts of electrolyte being lost by this p:1tient. During this period of marked fluid and electrolyte loss, it was necessary to collect all drainages and to analyze aliquots for their electrolyte content. As nearly as possible, a qua:[ltitative replacement was made of the fluid lost. It was helpful to estimat.e the total chloride requirement initially from the "thiocyanate available fluid" and the plasma chloride level, and to keep a record of the chloride exchange for estimation of daily fluid requirements. A graphic representation of this chloride exchange is shown in Figure 615 and the figures illustrated are listed in Table 1. It will be seen that this patient exchanged from one-half to twocthirds. of his total extracellular chloride within a twentyfour hour period. From the Harrison Department of Surgical Research, Schools of Medicine, University of Pennsylvania and the Surgical Clinic of the Hospital of the Universi.ty of Penn_sylvania, Philadelphia. '" l:[lstructor in Surgery, School of Medicine, University of Pennsylvania; Resident in General Surgery, Hospital of the University of Pennsylvania. 1849 10

1850

JAMES WALKER, JR.

I Electroll,lbz

Loss i.n a. Surgi.co.l futtent (L.McA.l

I

150-

HO130 1~0-

110 100 -

Ca= K

90130~ IS

'lO-

.:::::

60-

-

No

,.j.J

rj

~

50 -

~

40-

I

;co -

30-

lO-

rP

~R

f-

Cl

URINE

rOB

TOTAL meQ. K lZ·8 lost / ;(4 hrs. No. 10'9

P ;(3·2 Cl 1'14·3

GASTRIC DRAINAGE 1·49'7 11'1,4-

3·4 189'5

ILEOSTOMY

SWEAT

13'1 18·4

1·8

465·4

6·2.

17·3 444·4

'1·8

Fig. 614.-The maximum twenty-four hour electrolyte loss in a surgical patient draining small bowel content from an enterostomy. This figure shows graphically the relative concentration of the common electrolytes in urine, gas tric drainage, ileostomy drainage and in sweat in the case of the patient reported. The stick graph gives concentrations in milliequivalents per liter of the respective fluids. The subscript lists the total amounts of electrolyte lost by this patient in a given twenty-four hour period. This represents the maximum loss during the period of drainage which lasted for several weeks. Quantitative collection was made of urine and drainage. The sweat electrolyte content was estimated by analysis of filter paper patches placed on the patient's skin.

It was possible to maintain this patient with large volumes of intravenous electrolyte solution, including Ringer's solution and potassium chloride. Repeated blood transfusions were also necessary. Eventually it was possible to close the ileostomy and this patient has made a complete recovery.

This case is illustrative of the small percentage of general surgical patients whose fluid balance problems are not easily handled. The patient with a fistula at some point in the stomach or small intestinal

1851

FLUID AND ELECTROLYTE REPLACEMENT

I I

f

1

~

~

3

4

5

6

'Z

8

~

9

10

--Da.ys---Fig. 615.-Total exchange in extracellular chloride. This figure illustrates the exchanges occurring in the total extracellular chloride in the case reported. By "total extracellular chloride," the author means that amount of chloride found in the plasma volume and in the interstitial fluid. This is calculated clinically by measuring the "thiocyanate available fluid" and the plasma chloride concentration. The total extracellular chloride is calculated on the assumption that the concentration of chloride in the interstitial fluid is the same as that in the plasma. The horizontal line at the upper limit of the graph indicates the level of total extracellular chloride for this patient in the normal state. On the first day this patient's actual extracellular chloride was calculated and on the basis of this and a measurement of the total chloride loss and intake on succeeding days, the fluctuations in total extracellular chloride were calculated and plotted as the curving line. As a check on the reliability of such calculations, additional determinations of the "thiocyanate available fluid" and of plasma chloride were made at sveeral points, and the calculated total extracellular chloride on the basis of the data is plotted on the graph as a small square. It will be seen from inspection that there is a reasonably ~lose agreement between the value calculated from loss and gain of, chloride:each day, and the value calculated from the actual measurement of total extnibellular chloride.

tract loses large amounts of :water and electrolyte which would be normally reabsorbed. There is often serious impairment of nutrition. The escape of intestinal secretions may take place through an abnormal passage, created by trauma, infection or operation. The loss of secretions

l852

JAMES WALKER, JR.

may occur quite as readily when prolonged suction is applied to an indwelling tube in the stomach or small bowel. These patients may lose as much as 7 liters of electrolyte solution each day. The maintenance of normal water and salt relationships is often a difficult matter in such cases. I have found it helpful to estimate the deficits in these cases of (1) total circulating plasma protein and red cell mass, (2) water, particularly the interstitial water, and (3) the sodium and chloride ions. ESTIMATION OF DEFICITS IN DEHYDRATED PATIENTS

Estimation of Circulating Blood Volume.-The determination of total circulating plasma protein and red cell mass necessitates measuring the plasma volume or total blood volume. The technic for measurement of any volume of fluid within the body is based on the principle of dilution. A known mass of a traceable substance is introduced, which by its chemical or physical properties is presumed to be confined to the fluid space in question. After adequate mixing of the test substance within the fluid compartment, a sample of the fluid is analyzed for the test substance and the effective volume of the fluid in question can be determined from the concentrations measured. Plasma volume may be conveniently measured by the use of the blue dye T-1824. 2 , 3 This substance mixes with the circulating plasma volume in the normal patient within about fifteen minutes. It is slowly lost from the circulation at a rate which is a constant for the given patient under the conditions of the given day. It has been found necessary to know accurately the amount of dye given and to obtain plasma dye concentrations at three different times following injection (usually fifteen, thirty and forty-five minutes). In addition, any samples showing hemolysis should be discarded. Knowing the plasma volume and the plasma protein concentration, one may calculate the effective circulating plasma protein. In a similar manner, using the hematocrit reading, one may obtain a value for red cell mass or total blood volume. These figures thus obtained are compared with a theoretical normal figure related to height and ideal weight. From such comparisons the deficit is measured and replacement therapy can then be instItuted. Estimation of the Interstitial Water.-This flUId volume is also measured with a dilution technic, using a test substance which has the ability to diffuse uniformly throughout the extracellular space, including the plasma volume. Substances employed fall into two general groups; the inert carbohydrates and electrolytes. In the former group are such substances as inulin and mannitol, whils the electrolytes used commonly are sodium, chloride and thiocyanate. The determination of the carbohydrates is time-consuming, whereas, the electrolytes are more easily determined! None of the electrolytes are ideal for they all pass into cells

FLUID AND ELECTROLYTE REPLACEMENT

1853

to some extent. However, here again, as with the T -1824 technic, if the normal values are determined in the same manner, one obtains reliable data on relative shifts in this fluid compartment. For purposes of the present study, 0.7 gm. of thiocyanate 4 (20 m!. of a 5 per cent solution of sodium .thiocyanate) were injected following withdrawal of a blank blood specimen. Allowing one hour for equilibration, a second blood specimen was taken, as well as a quantitative collection of urine voided during the hour. The "thiocyanate available fluid" space was then calculated from the concentrations, allowing for urinary loss. Care was taken to avoid determination of the thiocyanate space while patients were receiving intravenous glucose solution. Other investigators have shown in experimental animals that an infusion of 5 per cent glucose in water increases permeability of muscle ll.nd skin cells for thiocyanate, thereby producing a spuriously high result. This observation has been confirmed in the human subject in the present series of observations. Apparently the effect is noticeable only at the time that the glucose infusion is in progress. By subtracting the plasma volume from the "thiocyanate available fluid" volume, one may obtain the interstitial fluid volume. Estimation of Sodium and Chloride Deficits (Knowing the "thiocyanate available fluid" volume and the plasma volume).-In the case of the markedly dehydrated patient seen for the first time in the hospital, one is faced immediately with the problem of correcting such a state and possibly of preparing this patient for emergency operation. It has been found helpful to make an immediate estimate of the patient's plasma and blood volume, serum sodium and chloride, and of the "thiocyanate available fluid". These determinations require about one and one-half hours time during which replacement of blood and of salt solutions may be in progress, the total amount replaced being subject to the results of the analysis. An index to the amount of salt-containing fluid needed in such emergency cases may be obtained from the "thiocyanate available space" and the plasma chloride concentration. Assuming for the purposes of rough. calculation that the chloride concentration in the extracellular space~s the same as that of the plasma, then the following formula will give the required chloride replacement in milliequivalents. Where

W

body weight in kilograms plasma chloride concentration in milliequivalents E = measured thiocyanate space in liters

P

= =

Then: 21 \V - PE = chloride deficit in milliequivalents.

Replacement of this· chloride deficit is then accomplished with physiological saline solution on the baSIS that 1 liter of 0.9 per cent sodium chloride contains approximately 154 milliequivalents. The advent of the flame photometer has greatly simplified determination of sodium and potassium content of biological fluids. Knowing

1854

JAMES W AL:K:ElR, JR.

sodium concentrations of plasma, it is possible to calculate sodium deficits in these patients in a manner similar to that used for total extracellular chloride. MAGNITUDE OF WATER AND ELECTROLYTE LOSS

The pattern of electrolyte depletion is dependent naturally on the volume and salt content of the secretion lost. Table 1 illustrates the relative concentrations of some electrolytes in secretions lost from the upper gastro-intestinal tract. TABLE 1 TOTAL EXTRACELLULAR CHLORIDE AND CHLORIDE EXCHANGE (MEQ,)

L. Mc. A. 68 kg. Theoretical normal extracellular space 14,300 ml.

Day

1 2 3 4 5 6 7 8 9 10 11

Thiocyanate Space

Measured Extracellular Chloride

Estimated Extracellular Chloride

mEq./l.

ml.

mEq.

mEq.

92 88 87 87 85 92 106

12,300

1110

13,700

1190

14,400

1320

109 95 102

15,300

1420

1268 1378 1219 13B9 1350 1299 1491 1675 1480

Out

In

Plasma Chloride

mEq.

mEq.

151 263 658 711 565 466 535 155 456 353 268

309 373 509 861 546 415 727 339 261 320 420

In general, gastric juice contains a preponderance of chloride although sodium and phosphate are lost in conmderable quantity. The patient with pyloric obstruction, therefore, will develop an alkalosis, due to the loss of excessive quantities of chloride ion. There will be a marked dehydration accompanied by some lowering of total base as the result of sodium loss and as a compensatory action by the body to avoid extreme alkalosis. . The loss of bile and pancreatic juice in addition to gastrIc juice increases the volume of fluid and electrolyte lost. Because of the composition of these secretions, the loss of sodium is proportionately greater than in the loss of gastric juice alone. The volume of secretion lost is as important as the electrolyte concentrations. Patients with pyloric obstruction will lose 2 to 3.5 gm. of sodium and 6 to 10 gm. of chloride in a total volume of 1.5 to 2.5 liters. The patient with a duodenal or high jejunal fistula will lose 6 to 10 gm. of sodium and 10 to 20 gm. of chloride in a volume of 3 to 5 liters of fluid.

FLUID AND ELECTROLYTE REPLACEMENT

1855

The patient with a low small intestinal fistula will lose a secretion approximating mammalian Ringer's solution. The volume of fluid lost will be much greater than at a point high in the gastrointestinal tract, amounting to as high as 6 to 8 liters a day, containing as much as 35 gm. of sodium chloride. The problem of replacement therapy in these patients is almost an individual matter. In general, it is obvious that they must have water TABLE 2 CONCENTRATION OF ELECTROLYTES LOST IN GASTRIC SECRETION Milliequivalents per Liter

Patient P. B. J.K. M.E. H. deG. C. B. A. P. H.M.

Na

K

CI

P

88 66 57 116 110 70 54

6 15 6 6 16 11 5

34 88 112 126 68 25 10

10 89 28 51 1 15 3

--- --- --- --Pyloric Pyloric Pyloric Gastric Gastric Gastric Gastric

obstruction obstruction obstruction stlCtion resection resection resection TABLE 3

THE CONCENTRATION OF CERTAIN IONS IN A NUMBER OF SOLUTIONS COMMONLY USED FOR 'INTRAVENOUS ADMINISTRATION .. -

~

-

-

Na

PSS ................. Amigen ....... , ...... Ringer's ............. Na and KCI. ........ Plasma .............. Blood ............... 2% NH 4CI. .......... M/6 Na Lactate .....

K

Grams per 100m!.

mEq./!.

3.33 0.79 3.11 1.67 3.34 1.84

145 34 135 73 145 80

3.83

162

CI

Grams per 100 m!.

mEq.!!.

Grams per 100m!.

I mEq./l.

0.07 0.24 3.14 0.15 0.20

1.8 8 80 3.8 5.1

5.17 1.21 4.30 5.43 3.65 2.91 13.3

145 34 121 153 103 82 372

and the proper salt replacement to overcome dehydration. The use of glucose is preferred to other sources of caloric intake because it supplies added water in the course of metabolism. The use of protein in the dehydrated patient has the disadvantage that its metabolism requires water for excretion of nitrogenous wastes. No two patients with pyloric obstruction will lose fluid of the same electrolyte pattern. This is equally true for fluid loss from any part of the boweI.T~ble 2 illustrates the electrolyte content of gastric drainage

1856

JAM.I!lt:l WALK.I!llt, Jlt.

in a gro.UP of patients with pyloric o.bstruction, and in a few patients who. have had delayed gastric emptying fo.llo.wing gastric resection. The difference in gastric acidity alo.ne is respo.nsible for much variation. The same variation in electro.lyte co.ntent is fo.und amo.ng patients lo.sing fluids fro.m o.ther parts o.f the bo.wel. In addition, patients may lose secretio.ns from more than o.ne portio.n and their to.tal lo.ss will be co.rrespo.ndingly greater. Because o.f these variatio.ns, it has been fo.und advisable to. have available a variety o.f so.lutio.ns for co.rrectio.n of l1uid deficits. A list o.f so.me so.lutio.ns with their salt co.ntents is given in Table 3. Using these singly o.r in co.mbinatio.n, co.rrectio.ns may be made fo.r deficits in circulating blo.od vo.lume, dehydratio.n and co.existing alkalo.sis o.r acido.sis. THE OCCURRENCE OF POTASSIUM DEFICITS IN DEHYDRATION

The patient o.n parenteral fluid replacement, taking no.thing by mo.uth fo.r lo.ng perio.ds o.f time, will frequently develo.p lo.w serum po.tassium levels. Values o.f the o.rder o.f 2 milliequivalents per liter are co.mmo.nly seen, the no.rmal range being 3.5 to. 5 milliequivalents. In sp~te o.f a co.mplete absence o.f potassium in the intake, these patients will continue to lo.se potassium in the urine. There is apparently little or no attempt on the part o.f the kidney to. conserve this catio.n. There is also. a continued loss in gastrointestinal secretions which, with the urinary loss, may total several grams daily. The objective evidence for a state of potassium depletion exists in observation of electrocardiographic changes in these patients and in measurement of the amount o.f retention of administered potassium. 6 • 6 Patients in diabetic acidosis o.r patients with low serum potassium levels during a period of pro.longed parenteral feeding without potassium replacement will develop characteristic Ekg changes, such as prolongation of the S-T segment and flattening or inversion of the T waves. These changes are reversed upo.n administration o.f potassium s011.1t~n~. 7. 8. 9 These same. patien.ts when given pota~siu~. solution .~ill retam the greater portIOn o.f It, whereas, normal mdIvIduals excrete much of the added electrolyte. Apparently this state o.f potassium depletion is mediated in large part by the kidney in the absence of potassium intake. Regardless o.f the lack of potassium in the intake in these patients, the kidney continues to excrete 0.5 to 1 gram of potassium daily. In a state of dehydration, water is lost from the plasma volume and extracellular fluid volume initially. As dehydration advances, there is a loss of water from the intracellular space with a re~tiltant shift of sodium into the cells and potassium out of the cells. The potassium thus displaced is immediately excreted. The effect of this so-called depletio.n is as yet not clearly understoo.d. States of otherwise unexplained alkalosis have been noted with hypochlo.remia which Were refractory to therapy until potassium is also given. With plasma s~dium concentrations in the normal o.r low

FLUID AND

ELEC~ROLYTE

REPLACEMENT

1857

normal range, such patients develop blood pH of the order of 7.55 and show clinical tetany in extreme cases. REPLACEMENT OF OTHER IONS

The question may be logically raised as to the importance of replacing all substances lost in abnormal fluid drainage. Obviously this is ideal, but with the methods available at the present time it has seemed impractICal from the point of view of the number of patients requiring such care and the time and effort required to do the requisite analyses to make up the fluids for replacement. In cases of prolonged fluid loss from such routes as duodenal fistula or ileostomies, it has been customary to use a mammalian Ringer's solution and to supply additional fluid and ions as required to correct obvious imbalance. COMMENT

In the management of the simple surgical case, one may assume certain average fluid losses and base replacement therapy upon these figures with reasonable assurance. In a small percentage of surgical cases, there is an exceptionally large loss of fluid and electrolyte by abnormal routes. These patients present complex problems in the estimation of existing deficits and in estimation of daily replacement needs. It is believed that one may obtain information useful in the handling of this type of patient from a few estimations. An estimate of the plasma volume is helpful when considered in conjunction with determination of plasma protein and the hematocrit reading. One may calculate deficits not only in the fluid volume of the plasma but also in the total circulating protein and in the red cell mass or total circulating blood volume. An estimate of the "thiocyanate available fluid" gives a clue to the state of hydration of the interstitial space. The "thiocyanate available fluid" minus the plasma volume is the interstitial space. In the normal individual, the "thiocyanate available fluid" is about 21 per cent of the body weight. Determination of plasma chloride and sodium in conjunction with the "thiocyanate available fluid" permits the calculation of total extracellular chloride and sodium. This is useful as a base line estimate of electrolyte deficiency and makes possible more reliable estimates of the needs of the body for sodium and chloride than have been possible by clinical methods based on ionic concentrations alone. By starting with an estimation of the total extracellular chloride and, keeping a careful record of volume and electrolyte content of all secretions lost, the clinician can estimate the patient's daily fluid and electrolyte replacement needs.

1858

JAMES WALKER, JR.

The observation of urinary electrolyte excretion or of plasma electrolyte levels alone will often give incomplete or actually misleading information. Iq th~ patient who is receiving parenteral replacement for long periods of time, it is believed that the administration of potassium in addition to other ions is warranted. The kidney in such patients continues to excrete potassium mobilized from the cells, in spite of an apparent overall deficit. In replacing potassium, one must exercise care in the case of patients with poor renal function, as such individuals unpredictably retain potassium and hyperpotassemia is a potential cause of cardiac arrest. SUMMARY

In patients with severe fluid imbalance, determinations of plasma volume i:tnd of "thiocyanate available fluid," in addition to the usual determinations of the hematocrit and of the concentrations in the plasma of chloride carbon dioxide and protein, are of great assistance. They permit much more quantitative estimations of the patients requirements for red cells, plasma protein, water and salt. The flame photometer makes practical the determination of sodium and plasma in body fluids and affords additional information of great value. On the basis of data obtained in this way, it appears that the replacement of potassium ions is warranted in most patients receiving prolonged parenteral replacement therapy. REFERENCES 1. Ravdin, I. S. and Walker, Jr., J.: Fluid and Electrolyte Balance. S. CLIN.

NORTH AMERICA 29: 1583 (Oct.), 1949. 2. Gibson, 2nd., J. G. and Evelyn, K. A.: Clinical Studies of the Blood Volume. IV-. Adaptation of the Method to the Photoelectric Microcolorimeter. J. Clin. Investigation 17:153, 1938. 3. Krieger, H., Storaasli, J. R., FriedeII, H. L. and Holden, W. D.: Comparative Study of Blood Volume in Dogs. Proc. Soc. Exper. BioI. & Med. 68:511, - 1948. 4. Cranda.lI, Jr., L. A. and Anderson, M. X.: Estimation of the State of Hydration of the Body by the Amount of Water Available for the Solution of Sodium Thiocyanate. Am. J. Digest. Dis. & Nutrition 1:126,1934. 5. Frenkel, M., Green, J. and Willebrands, A. F.: Low Serum Potassium Level During Recovery from Diabetic Coma with Special Reference to Its Cardiovascular Manifestations. Arch. Int. Med. 80:728, 1947. 6. Hepburn, J. and Graham, D.: Electrocardiographic Study in 123 Cases of Diabetes Mellitus. Am. J. M. Sc. 176:782, 1928. 7. Nadler, C. S., BeIIett, S. and Lanning, M.: Influence of Serum Potassium and Other Electrolytes on EKG in Diabetic Acidosis. Am. J. Med. 5:838, 1948. 8. Nicholson, W. M. and Branning, W. S.: Potassium Deficiency in Diabetes. J. A. M. A. 134:1292, 1947. 9. Butler, A. M., Talbot, N. B., Burnett, C. H., Stansbury, J. B. and MacLachlan, E. A.: Metabolic Studies in Diabetic Coma. Tr. Assoc. Am. Phys. 60:102, 1947.