Original Article
Electrolyte Status in Birth Asphyxia Pallab Basu, Sabyasachi Som1, Harendranath Das and Nabendu Choudhuri1 Departments of Biochemistry and 1Pediatrics, Burdwan Medical College and Hospital, Burdwan, West Bengal, India
ABSTRACT Objective. To study electrolyte status in asphyxiated newborns of different severity in early neonatal period and compare with controls. Methods. Sodium, potassium and total calcium levels were estimated in the serum samples of asphyxiated newborns of different severity and control group immediately after birth. Results. Mean serum sodium level was significantly lower (122.1 ± 6.0 mEq/L vs 138.8 ± 2.7 mEq/L; P < 0.001), mean serum potassium was higher (5.05 ± 0.63 mEq/L vs 4.19 ± 0.40 mEq/L; P < 0.001) and mean serum calcium level was found lower (6.85 ± 0.95 mg/dl vs 9.50 ± 0.51 mg/dl; P < 0.001) in cases than controls. Among cases, a strong positive linear correlation was found between the serum sodium, serum calcium levels and their Apgar scores, between sodium levels and total calcium levels and significant negative linear correlation between Apgar scores and serum potassium level. Conclusion. Among cases, hyponatremia and hypocalcemia developed early and simultaneously and the decrease in their serum levels was directly proportional to each other and to the degree of asphyxia. Though, mean potassium level was within the normal limit, the value was higher among cases than controls and directly proportional to asphyxia. [Indian J Pediatr 2010; 77 (3) : 259-262] E-mail: basu_pallab@ yahoo.co.in;
[email protected]; Dr.pallab_basu@ rediffmail.com
Key words: Apgar score; Serum sodium; Serum potassium; Serum total calcium; Perinatal asphyxia
Perinatal asphyxia one of the most common primary cause of mortality (28.8%) and morbidity among neonates in India and is the commonest cause of stillbirths (45.1%).1 An Apgar score of less than 7 at one minute and at 5 minutes respectively is seen in 8.4% and 2.45 cases in India.1, 2 This study was done to evaluate electrolyte status in asphyxiated babies immediately after birth when normal babies require no additional electrolytes. Sodium, potassium and calcium are the major electrolytes in human body, and any deviation from their normal levels in blood might cause convulsions, shock and other types of metabolic abnormalities. Calcium is an important second messenger in our body and also helps carrying out muscle function and acts as cofactor for several enzymatic activities. Body should maintain optimum level of these electrolytes in blood. Gupta et al showed lower serum sodium levels among
Correspondence and Reprint requests : Dr. Pallab Basu, Akriti, Grond Floor Flat, 13, Dr. Nilmoni Sarkar Street, Kolkata – 700090, West Bengal, India. [DOI-10.1007/s12098-010-0034-0] [Received June 6, 2008; Accepted October 24, 2008]
Indian Journal of Pediatrics, Volume 77—March, 2010
asphyxiated babies as compared to the control group and no statistically significant difference in the serum potassium levels between cases and controls.3 Jajoo et al showed a significant low serum calcium levels in asphyxiated babies than controls. 4 They have not mentioned whether the reduced sodium and calcium levels were in proportion to the severity of asphyxia or they were randomly decreased. Studies to find out changes in sodium, potassium and calcium levels in different degree of asphyxia are still lacking. No previous studies were simultaneously done on serum sodium, potassium and calcium. The present study was undertaken to assess the electrolyte status of newborn immediately after birth to find out any correlation of levels of serum sodium,potassium and calcium with different severity of asphyxia. MATERIAL AND METHODS This was a hospital based case control study following simple random sampling method where the cases and controls were selected in equal numbers on a particular day in a week applying inclusion and exclusion criteria. In a series of 100 newborns selected, 50 babies were asphyxiated and other 50 were healthy. The study was 259
Pallab Basu et al approved by the Institutional Ethical Committee, and informed consent was obtained from the parents of each subject. Both cases and controls were full-term newborn babies of 2.5 kg or more, admitted to the (NICU) Neonatal Intensive Care Unit. Cases had Apgar scores less than 7 and controls were with Apgar scores 7 or more at 5 minutes of birth. Babies with congenital malformations, serum creatinine levels more than 1.5 mg/dl, suspected metabolic disease, treated with diuretics and those born to mothers having hypertension, diabetes mellitus, toxemia of pregnancy, receiving general anesthesia, Pethidine, phenobarbitone, magnesium sulphate and other drugs likely to cause depression in babies, and mother with history of febrile attack within 2 weeks before delivery were excluded from the study. Babies of mothers having pre and immediate post delivery abnormal serum electrolyte status were excluded from the present study. Babies in the present study or control groups did not receive any medications except vit. K prior to the collection of blood samples. Serum total calcium was estimated in auto-analyzer (model ERBA XL 600) by end point coloriometric (OCresolpthalein Complexone or OCPC) method.5 Serum sodium and potassium were estimated in ion-selectiveelectrode in an electrolyte analyzer (model AVL 9181) which is based on the principles of potentiometry.6 Serum creatinine was estimated by modified kinetic Jaffe’s method in auto-analyzer.7 The results of the cases and control groups were compared in order to evaluate whether there was any difference in the sodium, potassium and total calcium levels between these groups. The results of the patients and controls were compared with their Apgar scores in order to determine whether the values of those electrolytes had any variation in different severity of asphyxia. The statistical data analysis was done using SPSS [Statistical Package for the Social
Sciences (SPSS Inc.)] software for windows, version 10. RESULTS Of the 50 cases male were 32 and female 18, mean birth weight was 2.62 ± 0.44 kg, 20 were delivered vaginally and rest were delivered by emergency cesarean section. Of the 50 controls males were 29 and rest were females, mean birth weight was between 2.76 ± 0.52 kg, 46 were delivered vaginally and rest 4 by elective cesarean section. Statistical comparisons of measured values between the two groups were performed by the two tailed unpaired ‘t’ test of the means. It was found that the mean serum sodium level was significantly lower in cases than controls. Within the asphyxia patients, significant positive correlations were found between the serum sodium level and the Apgar score. Mean serum potassium was slightly higher among cases than controls. Mean serum calcium level was found lower among cases as compared to the mean value in controls. There was significant negative correlation between Apgar score and serum potassium level and strong positive correlation between Apgar score and serum calcium level. Bivariate distribution analysis was used to determine the correlations and correlation coefficients. Simple linear regression was used to show the correlation and dependence between the values of the electrolytes and Apgar score. Table 1 and 2, Fig. 1, 2 and 3 detail the above results. DISCUSSION Hypoxic ischemic brain injury is the most important consequence of perinatal asphyxia. Normal serum levels of these three electrolytes in a newborn baby within 24 hours after birth are serum sodium level is between 134 –
TABLE 1. Mean Values of Electrolytes in Cases and Controls Parameters
Cases (N=50) Mean ± Standard Deviation (x ± S.D)
Controls (N=50) Mean ± Standard Deviation (x ± S.D)
P – values
Serum sodium Serum potassium Serum calcium
122.1 ± 6.0 mEq/L 5.05 ± 0.63 mEq/L 6.85 ± 0.95 mg/dl
138.8 ± 2.7 mEq/L 4.19 ± 0.40 mEq/L 9.50 ± 0.51 mg/dl
<0.001 <0.001 <0.001
TABLE 2. Correlation Coefficients and their Significance in Cases and Controls Parameters (r = correlation coefficient, P = Probability) CASES P values CONTROLS P values
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Correlation of serum Sodium & Apgar score (r, P) r=0.763, P<0.001 r=-0.052 P>0.7
Correlation of serum Potassium & Apgar score (r, P) r=-0.524 P<0.002 r=0.058 P>0.7
Correlation of serum Calcium & Apgar score (r, P) r=0.788 P<0.001 r=0.061 P>0.7
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Electrolyte Status in Birth Asphyxia Correlation of Apgar Score & Serum Sodium
Fig. 1. Linear regression analysis showing changes in serum sodium in relation to changes in Apgar scores in asphyxiated babies.
Correlation of Apgar Score & Serum Calcium
146 mEq/L,8 serum potassium and total calcium levels are between 3.0 – 7.0 mEq/L and between 9.0 – 11.6 mg/dl respectively. 9,10 In the present study it was found that there was significant decrease in extracellular sodium and calcium levels in the asphyxiated babies and the decrease was directly proportional to the degree of asphyxia. Although the serum potassium levels were within normal limits both in asphyxiated and control babies, the potassium levels among cases were higher than the levels in controls and were statistically significant. Also the values of serum potassium among the asphyxiated babies were directly proportional to the severity of asphyxia or inversely proportional to the Apgar scores. It was also found that rise in the serum potassium level was not of clinical significance, and its changes in the serum levels were not at par with the decrease in the levels of other two electrolytes. Also this hyponatremia and hypocalcemia, which developed perinatally, proportionally contribute to the development of more and more severe asphyxia if not rectified immediately. Control babies were discharged after 3 rd day of hospital stay; cases were discharged according to their recovery, 6 cases out of 50 died as per hospital records. CONCLUSION
Fig. 2. Linear regression analysis showing changes in serum total calcium in relation to changes in Apgar scores in asphyxiated babies.
Correlation of Apgar Score & Serum Potassium
It can be concluded that babies with perinatal asphyxia, develop hyponatremia (when serum sodium level less than 130 mEq/L) and hypocalcemia (when serum calcium level is less than 7 mg/dl) simultaneously soon after birth in proportion to the severity of asphyxia and grossly asphyxiated babies develop severe sodium and calcium deficits which may require immediate medical interventions.11, 12 So far the potassium level is concerned; further studies are required to reach any definite conclusion. At this stage it can only be said that there was no definite hyperkalemia (when the serum value is more than 6 mEq/L) of medical emergency.13 Acknowledgements Dr. Aninda Dasgupta, Associate Professor, Burdwan Medical College, had helped in statistical analysis by SPSS software. Mr. B. B. Mukherjee, Statistician, Dept. of Community Medicine, Burdwan Medical College, helped in different statistical analysis. Staff- nurses in baby nursery and labor room helped in collecting samples, Dr. Mousumi Tripathi helped in compiling data.
Fig. 3. Linear regression analysis showing changes in serum potassium in relation to changes in Apgar scores in asphyxiated neonates.
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Contributions: PB had done all biochemical analysis and laboratory tests, statistical analysis by SPSS software. He collected blood and other test materials from patients and took necessary consent from party, compiled data, master chart, and prepared the entire manuscript. SS guided PB in the whole procedures. HD and NC had finally proof-read the manuscript and had given valuable guidance during the research work period. Conflict of Interests : None. Role of Funding Source: None.
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