PARKLAND FORMULA AS A GUIDE FOR RESUSCITATION

loannovich 1, Alexakis D., Parker 1, Mantas N.

Centre of Plastic and Reconstructive SurgerV and MicrosurgerV, Athens General Hospital, Greece

SUMMARY. During a two-year period (1987-1988) 180 patients with bum injury were admitted to our clinic for acute care, 64 of them (35.5%) considered to be major injuries (over 25% T13SA), requiring fluid resuscitation. In this series all admissions were included, regardless of age, concomitant injuries or pre-existing diseases. Initial resuscitation was accomplished using the Parkland formula as a guide for resuscitation. This formula employs Ringer's lactate alone for the first 24 hour period giving a total amount of 4 ml/kg/% burn area. For the second 24 hour period it employs plasma at the amount of 0.5 ml/kg/% bum area and 5% glucose in an amount enough to maintain adequate. urine output. After the initial resuscitation, fluids were limited to the maintenance solutions. The efficacy of initial therapy was estimated by the determination of.. a) the accuracy of the resuscitation guides; b) the response of various organ systems (cardiovascular system, urinary system, pulmonary system, the balance of fluids and electrolytes; c) early mortality; and d) the complications encountered during the entire first, week post-burn period. According to our results the Parkland resuscitation formula provides a satisfactory urinary output, diminishes the development and accelerates the regression of the oedema. Thus it minimizes the possibility of renal failure and brain oedema. It contributes also to good electrolyte balance and is less expensive than the other formulae. On the other hand it necessitates large amount of fluids, which need a well organized team work with the nursing staff and a close monitoring of the clinical and laboratory paremeters for the control of the massive fluid infusion.

It is a well accepted axiom in the treatment of burns that the efficacy of resuscitation diminishes the frequency and severity of complications, resulting in a reduction of mortality. The improvement of the understanding of burn pathophysiology has led to the development of various formulae for the initial treatment of hypovolaernia.

Moyer et at. (1965) proved the contribution of the Na+ ion in the intra- and extracellular distribution of electrolytes and water during the initial period of burn disease. As a consequence Baxter (1974) introduced the Parkland formula for fluid volume replacement.

This formula has become popular and many investigators are still lauding its advantages (Pruit 1978, Goodwin et al. 1983, Bowser-Wallace and Caldwell 1986).

During the two-year period, 1987-1988, 180 adult patients with burn injuries were admitted to our department for acute care. 64 of them (35.5%) were over 25% TI1SA, requiring fluid resuscitation. In this series all admissions were included, regardless of age, concomitant injuries or pre-existing diseases. Initial resuscitation was accomplished using the Parkland formula as a guide.

The first 48 post-burn hours are divided into six 4-hour periods in order to facilitate the nursing routine and eliminate possible complications arising from the large volumes of fluid infused. According to the formula we administer Ringer's lactate alone for the first 24 hours post-burn, giving a total amount of 4 ml/kg/% TI1SA (Fig. 1). For the second 24-hour post-burn we begin administering plasma in an amount of 0.5 ml/kg/% TBSA, during the first two periods in order to "expand" the intravascular volume (Fig. 2). Adequate urine output (50-100 ml/h) is maintained with the administration of 5%-glucose, according to the formula of SDSP (Scott, McDougall, Slade and Pruit 1978).

The rate of fluid administration is in accordance with Baxter's proposal (1979) in order to maintain the functional extracellular fluid volume within + 10% of the individually calculated volume. 50% of the calculated volume of Ringer's lactate is given during the first two periods and the rest is evenly administered over the remaining 4 periods.

Monitoring during the first post-burn days is focused to determine the possible complications and the efficacy of the initial therapy (Fig. 6). Many such parameters have been proposed, some of which, in our view, are not totally justified, since they give academic and scientific information, without substantial benefit to the patient's care. For this reason we estimate routinely the efficacy and the side effects of the initial therapy by the determination of:

1. Cerebral function, according to clinical criteria
2. Hourly urine output, ranging between 50-100 ml/h, in relation to urine specific gravity and creatinine value
3. Central venous pressure, every three hours, as a relative parameter only, since the pulmonary artery wedge pressure (PAWP), although accurate, is accompanied by a high complication rate especially when the Swan-Ganz catheter is inserted through burned areas

Haematocrit, every 6 hours, as a parameter of efficacy of the reduction of haemoconcentration c) Vital signs every hour (pulse rate, blood pressure, surface temperature and respiration rate).

Fig. 1

Fig. 2

Results

The overall fluid requirement was within 4 ml/kg/% T13SA, since the difference between the calculated and the given fluid volumes was not statistically significant (Fig. 3).

Taking into consideration the mean value (4.04 nil) and the standard deviation (0.89 ml), we observed a considerable discrepancy between the given and the calculated fluid volumes in 4 cases. An 18-year-old patient with electrical burns of an extent of 35% T13SA required 4,700 nil Ringer's lactate more than the calculated volume (5.9 ml/kg/% T13SA). A p = <0.10 20-year-old woman with thermal burns of 35% T13SA, treated on an air-fluidized bed, required 2,500 nil Ringer's lactate more (5.42 ml/kg/% T13SA). A comatose 83-year-old woman with 22% T13SA, burned as a result of a fall following a cerebrovascular accident, required 2,000 nil more (5.80 ml/kg/% T13SA). The fourth case was a 28-year-old man with 30% T13SA who attempted suicide during a severe depression of manic depressive psychosis; he required 2,600 nil more (5.23 ml/kg/% T13SA).

Fig. 3

The lethal potential of inadequate resuscitation was considered to last for only 7 days. During this period 12 patients, with varying extent of T13SA, died (Fig. 4). However it should be stressed that the average age of deaths in the group up to 75% T13SA was 78.4 years, while the overall average age of the patients in these groups was 43.4 years. It is of course ' evident that the mortality rate in the group with over 76% T13SA was extremely high (66.6%).

As regards the cause of death (Fig. 5), 5 died from acute renal failure, between the Ist and 7th post-burn day, despite attempts at haemodialysis in two cases. Two patients died from cardio-pulmonary arrest in the first 12 hours, probably due to cerebral oedema. One of these cases had exudative pericarditis, which was confirmed on post mortem. One patient, a 71-year-old nephrectomized woman with pulmonary oedema, died on the second post-bum day as a result of excessive fluid administration. This is the only case where our parameters remained within normal limits but failed to indicate the onset of such a complication. Two cases with burns of over 90% T13SA died from multiple organ failure during the first post-burn day.

The urine output during the first 24 hours was adequate, ranging between 40 and 55 ml/h, while on the second day a steady increase in output was noted after the administration of the calculated plasma volume.

Fig. 5

The specific gravity of the urine showed some fluctuation, but resulted in a fairly steady decrease from 1020 to 10 15.
The central venous pressure showed fluctuations during both the first and second post-bum days, independent of the urine output and haematocrit.

Fig. 6

The haematocrit seemed to fall on the second post-burn day, while during the first day it remained at relatively high levels.

Despite the large load of sodium during the first day, the levels remained constant and within normal limits. It is of interest that on the second post-burn day the levels also remained constant although the administered sodium rate by plasma is much reduced.
The potassium rate remained, during the first two days, within normal limits and hyperkaliaemia was never observed, even when the initial therapy was started 5-6 hours after the accident.

Fig. 7

A mild metabolic acidosis was a common observation, especially during the first 3 post-bum hours. The combination of Ringer's lactate with an enrichment of NaHC03 resulted in a final stabilization of the pH within the first 24 hours, which remained also normal during the second day.
While P02 did not seem to be affected, PC02 showed a steady diminution during the first 12 hours, and then remained stable within normal limits.

Fig. 8

Discussion

Since Coop and Moore (1942) the goal of burn resuscitation has been to maintain adequate tissue perfusion, which has been achieved by the previously proposed formulae of Evans, Mount Vernon, Brooke etc. The investigations of Moyer et al. and Baxter brought to light the importance of the sodium/potassium pool and the contrib~tion of the Na+ ion in the intra- and extracellular distribution of electrolytes and water. This led to the differentation in the conception of the administration of crystalloid solutions in the initial period of burn shock resuscitation. Thus, we adopted the use of crystalloid solutions according to the Parkland formula, since it is based upon the pathophysiology of bum disease by supplying an adequate amount of sodium during the first 24 hours.
According to our statistical evaluation, the accuracy of the calculated administered fluid volume was high. The discrepancy observed in 4 cases, where the administered volume was between 1.4 and 1.9 ml/kg/% T13SA, was due to other concomitant factors. In two of the four cases the reasons for the discrepancy were clear: the case of electrical burn, where the estimation of the burn surface area produced calculated fluid volumes considerably less than those required in practice, and the case of the patient nursed on an air-fluidized bed, where increased fluid loss due to evaporation caused by the bed is a well-established fact which should always be taken into consideration.
Analysing the early mortality, we found that up to an extent of 75% TBSA the average age was 78.4 years and the rate 12.9%. There were no deaths during this period in all the other age groups (average age 43.7 years). In burns over 76% T13SA the mortality rate was 83.3% and the overall average age was 34.3 years.
In burns up to 75% TBSA, almost all observed complications presented in elderly patients (over 65 years). In the younger age group there was one case of pulmonary oedema which was successfully treated, whilst in the older group the majority of the complications was also the cause of their early mortality.
Of the parameters evaluating fluid volume administration, urine output seems to be one of the most reliable indicators.
Comparing the mean value of urine volumes, there was a tendency in the extensive bums for the output to diminish gradually to less than 30 ml/h between 18 and 24 hours post-burn, indicating the necessity of beginning earlier plasma administration.
The specific gravity of the urine has a steady tendency to decrease but the fluctuations observed during the first two days did not exactly parallel the other more reliable parameters; however, its value was taken into consideration along with those of the hourly urine output and creatinine.
Central venous pressure was an unreliable parameter, but did help as a relative value during the administration of large amounts of fluid.
The curve of haematocrit values was observed to be a practically mirror image of that of the hourly urine output. Though it remained at high levels, despite the administration of large fluid volumes throughout the first 24 hours, it showed steady reduction after the administration of plasma at the beginning of the second 24 hours. We thus consider our division of the first 48 hours into 4-hourly periods of practical value, as it ensures even distribution of the fluid volumes administered and prevention of persistence of extreme haemoconcentration.
In conclusion, comparing our parameters with others in the literature (Baxter 1978, 1979, Pruitt 1978, Goodwin 1983), we have come to the conclusion that ' the Parkland formula is easily manipulated, even with the simplest clinical and laboratory parameters, and leads to successful resuscitation with the following advantages:

1. It is based upon the pathophysiology of burn disease by supplying an adequate amount of sodium.
2. The rate of administration of the large volumes of necessary fluids is easily regulated.
3. It limits the oedema of the extracellular compartment and thus the indications of escharotomy.
4. It provides the possibility of fast fluid administration after a delayed start of treatment, reducing the incidence of renal damage.
5. It diminishes the complication rate in both acute and later post-burn periods (acute vasomotor nephropathy, pulmonary oedema, gastric haemorrhage, etc.).
6. It retains a stable electrolyte balance without the necessity of additional administration.
7. It reduces the toxicity of myoglobulin in the renal tubular system by retaining a high urine output.
8. It facilitates early enteric nutrition (elemental or semi-elemental) by minimising the oedema of the g.i. mucosa.
9. Easy administration - low cost.

The only disadvantages observed, chiefly in extensive burns, are:

1. It requires intensive monitoring while administering the large fluid volume, particularly in infants and the elderly.
2. There is a rapid reduction of plasma albumin.

RESUME. Dans une période de deux ans (1987/88), 180 patients avec brûlures en phase aiguë ont été hospitalisés dans notre clinique, dont 64 (35.5%) avec lésions considérées graves (brûlures en plus de 25% de la surface corporelle) qui avaient besoin de réanimation liquide. Cette série incluait tous les patients hospitalisés, indépendamment de l'âge, des lésions concomitantes ou des maladies préexistantes. Pour la réanimation initiale la formule de Parkland a été utilisée comme guide réanimatoire. Cette formule prévoit l'emploi seul du lactate de Ringer dans la première période de 24 heures, avec l'administration d'une quantité de 4 ml/kg/% BSA. Dans la second période de 24 heures elle emploie le plasma dans la mesure de 0.5 ml/kg/% BSA et le glucose à 5% en quantité suffisante pour maintenir une production urinaire adéquate. Après la réanimation initiale les liquides ont été limités aux solutions de maintenance. L'éfficacité de cette thérapie initiale a été évaluée en déterminant: a) la précision des guides réanimatoires; b) la réponse des divers systèmes organiques (systèmes cardiovasculaire, urinaire et pulmonaire, équilibre des liquides et des électrolytes; c) la mortalité précoce; d) les complications rencontrées pendant l'entière première semaine après la brûlure. Selon les résultats exposés la formule de réanimation de Parkland permet une production urinaire suffisante, réduit le développement de l'oedème et en accélère la regression. Elle minimise ainsi le risque de l'insuffisance rénale et de l'oedème cérébrale. Elle est utile pour établir un bon équilibre électrolytique et son coût est inférieur à celui des autres formules. Par contre, elle nécessite une grande quantité de liquides, ce qui requiert un travail d'équipe bien organisé en collaboration avec les infirmiers et un monitorage attentif des paramètres cliniques et de laboratoire pour le contrôle de l'infusion massive des liquides.

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