Body fluid compartment changes following neonatal surgery

Body Fluid Compartment Changes Following Neonatal Surgery By Arnold G. Coran and Robert A. Drongowski

Ann Arbor, Michigan Q The neonate is born w i t h an excess of total body w a t e r (TBW) in the range of 75% t o 85% of body w e i g h t (v 60% in t h e adult), which is due t o a large extracellular fluid volume (ECF) of 40% to 50% of body w e i g h t (v 20% in t h e adult). In an a t t e m p t t o define t h e changes t h a t occur in TBW and ECF following neonatal surgery, the following prospective study was carried out. T w e n t y newborns w i t h major congenital anomalies (gastroschisis, 10; esophageal atresia, 4; ileal atresia. 3; omphalocele, 2; a n d m a l r o t a t i o n . 1 ) w e r e studied w e e k l y for 4 w e e k s following surgery w h i l e being maintained on a standard protocol of total parenteral nutrition (TPN). Total body w a t e r was measured using deuterium oxide, and extracellular fluid v o l u m e was assayed w i t h sodium bromide; both w e r e expressed as percent body w e i g h t (BW). Weight gain or maintenance was observed in all infants. TBW remained unchanged 9 (from 85.4% to 83.0%), and ECF decreased f r o m 61.2% to 36.7% during the observation period 9 The TBW in t h e ten gastroschisis infants decreased from 87.3% to 78.0% v t h e t e n o t h e r newborns, in w h o m t h e r e was no change (84.0% to 85.0%). The ECF changes w e r e m o r e dramatic, decreasing f r o m 51.6% to 32.3% in the gastroschisis infants, v 50.8% t o 45.5% in t h e o t h e r neonates (P = ,0156l. There w e r e no differences b e t w e e n t h e t w o groups in t h e intake and o u t p u t of fluids. The following conclusions w e r e drawn: (1) Following major surgery, newborns s h o w a steady decrease in ECF and minimal change in TBW in spite of adequate w e i g h t gain w h i l e receiving TPN. (2) Gastroschisis infants postoperatively experience a significant drop in ECF, which is accompanied by a moderate decrease in TBW. (3) This ECF deficit in the gastroschisis infants might be related to sequestration of fluid in the walls of the agglutinated, inflamed bowel and in the peritoneal cavity. 9 1989 by W.B. Saunders Company. INDEX WORDS: Fluid volume, neonate.

NFANTS ARE BORN with a total body water

I (TBW) content in the range of 75% to 80% of total body weight, which decreases to a value of 60% in the adult. 13 This large TBW is due to a large extracellular fluid volume (ECF) in the range of 45% to 50%, as compared with 20% in the adult. 47 The TBW of malnourished infants after the surgical treatment of congenital abnormalities of the alimentary tract was reported to be significantly increased, relative to normal infants, in spite of observable dehydration and wasting) In another study, however, there were no significant differences in TBW content between infants with intestinal obstruction in comparison with other newborns? All these factors make estimation of fluid requirements in neonates following major surgery very complicated, especially if a major dissection with

Journa/of Pediatric Surgery, Vo124, No 8 (August), 1989: pp 829-832

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StudyW e e k s Fig 1. Mean body weight; dark area denotes gastroschisis, shaded area denotes other.

tissue trauma occurs9 In these instances, the "normal" maintenance volume of 4 m L / k g / h often must be increased by a factor of four. ~~ Infants undergoing surgical repair of anterior abdominal wall defects might be expected to have complicated fluid requirements due to at least three factors: (1) the operation itself, (2) significant evaporative loss from the exposed intestines, and (3) sequestration of fluid in the walls of the agglutinated, inflamed bowel and in the peritoneal cavity. Survival of these infants has improved markedly with the use of prosthetic materials and the advent of intravenous (IV) total parenteral nutrition. H However, it has been reported that some of the observed morbidity results from difficulties of assessing fluid volume deficits in the early postoperative period.12 This study was undertaken to ascertain body fluid compartment changes in infants following neonatal surgery and to determine whether these changes are different in infants with gastroschisis as compared with a group of newborns with other surgically correctable anomalies.

From the Section of Pediatric Surgery, C.S. Mott Children's Hospital, University of Michigan Medical School, Ann Arbor. Presented at the 37th Annual Meeting of the Surgical Section of the American Academy of Pediatrics, San Francisco, California, October 15-17, 1988. Address reprint requests to Arnold G. Coran, MD, F7516 Mott Children's Hospital, University of Michigan Medical Center, Ann Arbor, MI 48109-0245. 9 1989 by W.B. Saunders Company. 0022-3468/89/2408-0023503.00/0

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CORAN AND DRONGOWSKI

2001

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Fig 3. Mean output volume; dark area denotes gastroschisiSo shaded area denotes other.

Fig 2. Mean input volume; dark area denotes gastrosehisis, shaded area denotes other.

MATERIALS AND METHODS

of 0.4% of injected volume over the three-hour equilibration period 14 using the following formula:

Twenty infants receiving peripheral or central total parenteral nutrition (TPN) following major surgery were studied prospectively for 4 weeks, after obtaining informed consent from the parents and in accordance with the standards established by the Human Use Committee. There were ten infants with a diagnosis of gastroschisis (group 1) and ten other neonates (group 2) with the following diagnoses: esophageal atresia, 4; ileal atresia, 3; omphalocele, 2; and malrotation, 1. The infants were studied prior to the administration of TPN and weekly during the TPN therapy. Following a baseline blood sample, deuterium oxide at 1.5 mL/kg and 5% sodium bromide at 2.0 mL/kg were injected IV. After three hours of equilibration, a second blood sample was drawn. The blood samples were centrifuged at 2,000 rpm for 15 minutes at 4~ and the serum removed. Serum bromide was measured by ion chromatography via a conductivity detector (Dionex Corp, Sunnyvale, CA). The extraeellular fluid volume (ECF) was calculated as the corrected bromide space by using the intracellular factor, 0.9, as reported by Fink and Cheek. t3 Deuterium oxide was measured by infrared spectrometry (Foxbore, Miran 1FF). Total body water was calculated given the known weight of injected deuterium oxide, the serum concentration of deuterium oxide, and the established deuterium oxide excretion rate

V

C]V] - C.V. C2

where, V = total body water in liters; Cj = concentration of injected deuterium oxide (0.997); Vj = volume of deuterium oxide injected corrected to 37~ (grams of deuterium oxide solution injected divided by its density at 37~ 1.10098 g/L); C,V, = total amount of excreted deuterium oxide from time of injection to time of sampling, ie, 3.0 hours (this represents insensible water loss plus urine loss and equals 0.4% of injected deuterium oxide [C]Vd); C2 = study serum concentration of deuterium oxide at equilibration. Daily weights as well as 24-hour fluid input and output were recorded during the study period. These data were subsequently reported as mean weekly values over each of the four seven-day periods. Statistical analysis was performed using the Student's t test, with a P value <.05 considered significant.

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T B W and ECF (all

BODY FLUID CHANGES AFTER NEONATAL SURGERY

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0 Fig 5. T B W and ECF for group I and 2 patients.

-1 Study Weeks

RESULTS

There were no significant changes in mean weekly body weight between group 1 (gastroschisis) and group 2 (other neonates) patients. Body weight increased slightly in group 1 infants but remained unchanged in group 2 neonates (Fig 1). Mean weekly volume of input and output (mL/kg) did not differ significantly between the two study groups (Figs 2 and 3). Mean T B W in all patients decreased slightly after the first week but then remained essentially unchanged for the remaining 3 weeks. In contrast, the mean extracellular fluid volume decreased steadily during the observation period from 51.2% to 36.7% body weight (Fig 4). The T B W in group 1 (gastroschisis) newborns decreased from 87.3% to 78.0% body weight in comparison with group 2 (other neonates), in whom there was no change (84.0% to 85.0%). The ECFs decreased from 51.6% to 32.3% body weight in group 1 patients, compared with a decrease from 50.8% to 45.5% body weight in Group 2 infants (P = .0156) (Fig 5). DISCUSSION

In our experience studying postsurgical infants receiving TPN, TBW decreases slightly during the

first week and then usually returns toward baseline values (about 80% body weight) during the first month of life. 4 In contrast, the ECF decreases from a value close to 60% of body weight to approximately 40% body weight during this time period. 4 These data indicate that the excess of T B W in neonates is due to a large extracellular space. Mean body weight increases during this same period, indicating that weight gain from IV nutrition is due to tissue accretion rather than fluid accumulation in these neonates. In comparing patients with gastroschisis with other infants undergoing major gastrointestinal (GI) surgery, the TBW changes are the same; however, the ECF decreases more dramatically in those infants with gastroschisis. In contrast, there were no significant differences observed in mean fluid input, output, or body weight. One possible explanation for this greater decrease in ECF in gastroschisis infants is the sequestration of fluid in the wall of the agglutinated, inflamed bowel and in the peritoneal cavity. This observation suggests that infants with gastroschisis might require more fluid both preoperatively and postoperatively than other newborns undergoing surgery for major GI anomalies. These data are consistent with the clinical observation that infants with gastroschisis require more colloid resuscitation before and after surgery than infants with other GI abnormalities.

REFERENCES

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and extracellular fluid volume in infants receiving total parenteral nutrition. J Podiatr Surg 19:771-776, 1984

water

5. Rhodin AGJ, Coran AG, Weintraub WH, et ali Total body water changes during high volume peripheral hyperalimcntation. Surg GynccolObstet 148:196-200,1979 6. PolicyTZ Jr, BennerJW, Rhodin AGJ, et ai: Changes in total body water in infants receivingtotal intravenousnutrition. J Surg Res 26:555-559, 1979 7. DrongowskiRA, Coran AG, WesleyJR: Modificationof the

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serum bromide assay for measurement of extraeellular fluid volume in small subjects. J Surg Res 33:423-426, 1982 8. Tsingoglou S, Phillips H, Wilkinson AW: Total body water in malnourished infants after surgical treatment. J R Coll Surg Edinb 26:272-277, 1981 9. Tsingoglou S, Phillips H, Wilkinson AW: Total body water content of neonates with obstruction of alimentary tract. Arch Dis Child 47:941-945, 1972 10. Coran AG, Behrendt DM, Weintraub WH, et al: Surgery of the Neonate. Boston, Little, Brown, 1978 11. Filler RM, Coran AG: Total parenteral nutrition in children:

CORAN AND DRONGOWSKI

Central and peripheral approaches. Surg Clin N Am 56:395-412, 1976 12. Philippart AI, Canty TG, Filler RM: Acute fluid volume requirements in infants with anterior abdominal wall defects. J Pediatr Surg 7:553-558, 1972 13. Fink CW, Cheek DB: The corrected bromide space (extracellular volume) in the newborn. Pediatrics, 26:397-400, 1960 14. Schloerb PR, Friis-Hansen BJ, Edelman IS, et al: The measurement of total body water in the human subject by deuterium dilution with a consideration of the dynamics of deuterium distribution. J Clin Invest 29:1296-1310, 1950