Nutritional assessment and surgical risk makers in children submitted to cardiac surgery

In order to assess the nutritional status of children with heart diseases and to evaluate nutritional parameters for predicting postoperative complications, 50 children undergoing to cardiac surgery and classified in high and low surgical risk prospectively evaluated. Assessment parameters included anthropometry and plasma proteins albumin, transferrin and prealbumin. The nutritional classification according to Waterlow's modified criteria showed a high prevalence of'malnutrition in the population studied (78%). The measures of arm circumference when located below the 5th percentile showed a significant association with general postoperative complications in the high risk group (arm circumference, p = 0,0019; arm muscle circumference, p = 0,0419). The percentage of weight per height, serum albumin and transferrin has not played a prognostic role conc~rning postoperative morbidity. The mean value of prealbumin was significantly lower in high risk group patients developing postoperative infections (p < 0,01) compared to those who did not. The sensitivity-specificity analysis of prealbumin as risk indicator for postoperative infection was 87.5% and 59% respectively. The nutritional risk classification seems to be a good way to identify the subgroups of children with additional postoperative surgical risk. However, more specific and sensitive tests are desirable to provide an individual identification of these children.


C
haracteristics such as malnutrition and growth retardation are frequently associated to congenital cardiopathies considering factors that may have contributed for this condition, besides a poor caloric nutrition (14,20), low vitamin and oligoelements (10), other reasons have been outlined such as hypermetabolism, cellular hypoxemia (18,19) and reduction of the intestinal absorption of the nutrients.

Address for correspondence:
Heitor Pons Leite Rua Rio Grande, 50 -Apto.84 Sao Paulo -SP -Brasil -CEP 04018-000 In cardiopathic children, malnutrition effects may be clinically much more important in situ~tions of metabolic stress, as 'it occurs when they are submitted to great surgeries.The surgical stress added up to a precedent hazardous nutritional status may become even more problematic, causing serious consequences tq the patient (15).This situation influences directly the hospital evolution parameters, causing delay in cicatrization (26), increase of postoperati ve infection rates (16), longer confinement period and morbidity rates increase (6).
There are very few works published regarding cardiosurgery (1,3) and literature does not present specific studies bearing pediatric aged patients.Based on evidences upon which malnutrition status may affect prognostic of • patients undergoing to surgery, it seems reasonable to believe that identification of patients with tendency to complications due to malnutrition, may enable a more approximate estimative of the surgical risk and help in his recuperation.We have considered opportune a study 9f the nutritional status of cardiopathic children selected for cardiosurgery and the parameters of nutritional evaluation as being risk indicators of postoperativ~complications of these children.

CASUISTIC AND METHODS
This study was approved by the ethics committee of the Escola Paulista de Medicina.

Sketch of the study
In a prospective study made during the period of October 90 till October 92, 50 cardiopathic children, chosen for a selective cardiosurgery at the Hospital Sao Paulo, were evaluated.Before surgery, each patient has been submitted to a nutritional evaluation and has been followed regarding his postoperative evolution till leaving hospital.Nutritional assessment comprised anthropometric and plasmatic protein dosage.

Patients
Patients were classified in two groups of surgical risk (high and low) according evaluation during pre, intra and postoperative periods, performed by the Cardiology Dept. of the Escola Paulista de Medicina, based on cardiopathies, clinical status and kind of surgery, based on the work of KIRKLIN & BARRATT-BOYES (11).Children identified with at least one of the items below were considered as pertaining to high surgical risk group: -Presence of previous cardiac insufficiency.
-Presence of outstanding lung hypertension, defined as a relation between the systolic pressure of the pulmonary trunk and the aortic pressure of more than 0.6, or a relation of the systolic pressure of the right ventricle over the left, higher than 0.6.
-Extracorporeal circulation presenting long perfusion time (more than 70 minutes).
-Unstableness of haemodynamic during intra or postoperati ve: shock, cardioinsufficiency, persistent arrhythmia or cardiac arrest during surgery.
Children not identified with at least one of these items, were classified as pertaining to low surgical risk group.The following were excluded from the study: patients born with less than 2.500 gr.weight, presenting renal and hepatic insufficiency, central paralysis, congenital immunology deficiency or infective process, and those who were submitted to blood transfusion during the last 30 days period.
High risk group, a total of 30 children, was mainly composed by patients presenting cyanotic cardiopathies and other cardiac diseases associated to significan~lung hypertension.The low risk group, formed by 20 children, was mainly composed by patients presenting acyanotic cardiopathies with pulmonary overflow.Table 1 shows children according cardiopathies and type of surgery performed.A control group was formed, composed by 20 eutrophic children submitted to a selective iniguinal or umbilical herniorraphy, who were laboratorie evaluated exactly according the same patterns as the children pertaining to the study group were submitted to.

Anthropometric
parameters considered weight, height, cutaneous triciptal plica, arm circumference and arm muscle circumference.For classification of nutritional condition, modified criteria of Water low were used (25,2).As reference for measures of weight, height and correspondent relation, standards adopted by the WORLDWIDE HEALTH ORGANIZATION were used (7).The percentage of weight per height located below percentile 10 was considered indicative of postoperative complications risk.Anthropometric measures of arm and calculation of brachial muscle circumference were obtained according procedures indicated in literature (8).
Cutaneous triciptal plica was obtained using the Lange's plicometer.Measures of the cutaneous triciptal plica, brachial circumferences and adipose and muscle areas of the arm in children less than 1 year old, were compared to FRISANCHO (8) standards, considering percentile less than 5 ~s postoperative morbidity risk indicator.All the anthropometric measures were taken by the same examiner.

Serumuria
dosage was obtained through green bromocresol (7)   Partigen@ Prealbumin and Nor-Partigen@ Transferrin (Behring) plaques.For the analysis of these proteins, a curve was outlined using three progressive dilutions of a standard serum.A 0.05% or 5% level was fixed for all the tests, in case of parity theory rejection.Protein plasmic evaluations as indicati ve of postoperati ve surgical risk were based on a previous sensibility and specificity analysis (9).Sensibility was defined as the percentage of patients presenting very high postoperative risk, selected according a high risk indicator of postoperative problems, among those who ~ave suffered complications.Specificity was defined as the percentage of patients selected according a low risk indicator of postoperative problems, among all who have not shown complications.Following were the values considered as being abnormal: albumin presenting" concentration below 3.5 g/dl and transferrin presenting concentration lower than 200 mg/dl.In what refers to .prealbumin, medium concentration of the high surgical risk group was considered as being the limit (19.6 mg/dl).

RESULTS
The main characteristics of the two surgical risk groups and frequency of postoperative complications are shown on tables 2 and 3 respectively.
Classification of the nutritional status may be observed on table 1, showing the nutritional condition of children presenting, respectively, high and low surgical risk.Prevalence of malnutrition was of 78%, 90% pertaining to the high risk group and 60% to the low risk group.In the high risk group 83.3% of the patients presented height x age below percentile 10 and same

DISCUSSION
firmly registered, it is limited in situations of ferrum deficiency, when its concentration is increased.In this study, 82% of the cardiopathic children carrying no cyanotic cardiopathies, presented hemoglobin values below normal levels, fact that may explain the normal serum transferrin value.The high prevalence of malnutrition in children studied are in accordance with literature data on proteincaloric malnutrition in cardiopathic children (13).The prevalence of malnutrition in the high risk group in comparison to the observed in the low risk grl)up may be explained by the fact that the first group was composed by children with more serious cardiopathies and the higher haemodynamic consequences.Another important factor distinguishing malnutrition situation between children of both groups was the prevail of low height in children showing high surgical risk.These data, in addition to the higher chronic malnutrition frequency, incline favorably for a previous and most intensive nutritional involvement in children presenting high surgical risks, probably associated to the cardiopathic seriousness.
Serum albumin rates in both surgical risk groups, although inferior to the control group, appeared within normal rates.Serum albumin, having a long lifetime and due to extravascular "pool" redistribution, does not reflect adequately the protein/caloric malnutrition, unless very late and 'when the protein offer is almost none.
Preoperati ve concentrations of transferrin appeared between normal levels in all the children studied (cardiopathies and control group).Although the value of this parameter for the malnutrition determination has been Sao Paulo Medical Journal/RPM 113(1) Jan/Feb 1995 Medium concentrations of prealbumin, similar in both of the surgical risk groups, were lower than the showed in the control group.'SALZER et al. (20), studying 16 children presenting congenital cardiopathies, observed that although presenting a shortage in weight x height and height x age, prealbumin values were within normal rates.In the present study, medium concentration of albumin in cardiopathic children was lower than the observed in the control group, nevertheless some of the children showing weight deficiency in comparison to their height, presented normal values of this protein.This result, in addition to the study previously reported, suggests that the prealbumin relevance in the individual nutritional assessment is already pending on a definition.
In the present study, parameters of the expected weight x height has not played a prognostic role concerning postoperative morbidity.Although a significant association between the measures of brachial and the brachial muscle circumferences, modified, and the postoperative morbidity, this calls for a very careful understanding.Anthropometric arm measures were only performed in children older than 1 year, in a total of 15 children of the high risk group, a number that may not be enough for considering the association observed as clinically significant.
It was not possible to separate children studied by the usual anthropological parameters based on weight and height, in groups of higher morbidity risk.This can be due, probably, to the fact that high risk group was composed, quite all, by children submitted to poor diet.As few patients showed normal rates, these parameters have probably lost their differential purpose.
Studies perform the malnutrition diagnose.More important, however, is identification of the nutritional parameters associated to the morbidity increase.This could enable a correct nutritional support to these children during a certain period before the surgery, improving their nutritional conditions so that they may face surgical trauma in more favorable conditions.In this study, the nutritional assessment enabled identification, within a group of patients basically malnutritioned and under high surgical risk, a subgroup of children with an additional postoperative morbidity risk.Need persists, however, in the identification of a parameter sufficiently sensitive ~nd specific, to characterize these patients individually.
.V. closure Total correction and ligature of the arterial channel Blalock Taussig Ligature of the arterial channel and closing of the CIV and CIA Closing of the C.I.V.Total correction Bipulmonary-cava anastomose CIV closure; aorta-VE tunneling Ventriculoplasty and aorta-VE tunneling Surgery of Senning Closing of CIV,CIA:ligature of the arterial channel Closing of C.I.V. and C.I.A.Total correction of OAVC and ligature of the arterial channel Mitral valve plastya Mitral plastya and change of the aortic valve C.I.V.closure Aorta-VE tunneling, C.I.V. and C.I.A. closure Implantation of pulmonary arteria in the pulmonary trunk and ligature of the arterial channel Ventriculoseptop Iasty Mitral plasty Total correction.of the anomalous drainage C.I.V. closure Ligature of the arterial channel Ligature of the fistule and the aneurysmal saccus Ligature of the arterial channel Aortic commissurotomy Bipulmonary-cava anastomose Ligature of the arterial channel Atrioseptoplasty and ligature of the arterial channel Blalock ,Taussig Transaortic myomectomy Ressection of muscle's band Bipulmonary-cava anastomose C.I.V.: intraventricular communication P.C.A.: arterial channel persistence D.A.V.P.: anomalous drainage of pulmonary vein E.M.: mitral stenosis H.P.: pulmonary hypertension O.A.V.C.: common osteo:-atrioventricular T.G.V.B.: transposition of the great base vases C.I.A.: intraarterial communication D.V.S.V.D.: double outlet of the right ventricle E.Ao.: aortic stenosis I.M.: mitral insufficiency E.P.: pulmonary stenosis D.V.E.V.E.: double inlet of the left ventricle

Figure 1 -
Figure 1 -Nutritional condition according Waterlow.scriterion based on the surgical risk

Table 1 Children according diagnose and surgery performed Surgery
method.Prealbumin and transferrin dosages were made through the single radial immunodiffusion method (12) using, respectively, M-n Diagnose

Table 2
C.E.C.: Extra-corporeal circulation 15% o o Sao Paulo Medical Journal/RPM 113(1) Jan/Feb.1995 Analysis of variance -Scheffe test * control> high risk and low risk t low risk> high risk

Table 5
Brachial circumference percentile in children of high risk group in the presence of postoperative complications

Table 7
(24) in what refers to prognostic capability of nutritional parameters in surgical patients.SYMRENG et al.(24)" studying adult patients submitted to selective surgeries, of different seriousness and risks, found lower albumin and prealbumin rates in the preoperative period in those who developed postoperative complications, the .ativeplasmatic protein levels as indicators of postoperati ve complications suggest that albumin is a very few sensible and specific parameter and transferrin has no value for this, once values were normal in all of the children.Prealbumin was a sensible parameter, although Preoperative values of prealbumin (mg/dl), tranferrin (mg/dl) and albumin (g/dl) in the high risk group in what refers to postoperative complications incidence specific in the prognostic of infectious complications in children pertaining to high surgical risk,' during the postoperati ve cardiosurgeries period.