European Journal of Cardiovascular Medicine

Even after much research, pneumonia has been a source of constant challenge for medical science, making it one of the longest recognized diseases to humans. In both the developed and developing worlds, childhood pneumonia is a major source of illness and mortality. It is also known as the "forgotten killer" or the "silent killer" since the death rate has stayed relatively constant throughout time. Childhood acute respiratory tract infections are referred to as the "Cinderella of communicable diseases" by R.M. Douglas.¹

All inflammatory conditions affecting the lungs, including the visceral pleura, connective tissue, airways, alveoli, and vascular systems, are strictly referred to as "pneumonia" or "pneumonitis." According to estimates from the World Health Organization (WHO), there are 156 million occurrences of pneumonia among children under the age of five each year, with up to 20 million cases being severe enough to necessitate hospitalization. According to estimates, the annual incidence of pneumonia in the industrialized world is 14.5 per 10,000 in children aged 0 to 16 and 33 per 10,000 in children under five.²

The most prevalent electrolyte imbalance among hospitalized patients, hyponatremia has been linked to a higher death rate. Hyponatremia is defined as a blood sodium concentration ([Na+]) of less than 135 mEq/L.3. Homeostatic systems including thirst, anti-diuretic hormone, and the renal processing of filtered sodium generally maintain serum sodium levels and serum osmolality under exact control.⁴

Both viral and malignant lung illnesses are commonly associated with hyponatremia. A recent single-center cohort research on pneumonia revealed that 28% of patients with community-acquired pneumonia (CAP) had hyponatremia upon hospital admission.⁵ This finding was linked to both an increase in hospital mortality and a longer hospital stay.⁶ In a prospective cohort research involving all patients hospitalized with CAP, Nair and colleagues discovered that 28% of the 342 study participants had hyponatremia, which was linked to an increased risk of hospital death.⁵

In 1920, lobar pneumonia was linked to water retention, a decrease in serum concentrations of fixed base and chloride, and a decrease in osmolality. Subsequent research has also linked pneumonia to an increase in extravascular fluid and plasma volume, as well as severe hyponatremia. Variations in fluid and electrolyte levels have been hypothesized to be caused by improper antidiuretic hormone (SIADH) secretion.^7,8 In India, pneumonia in children is a major source of both mortality and morbidity. Additionally, hyponatremia affects 1/4 of CAP cases and has been linked to a worsening of the disease's course and increased severity.

It is critical for clinicians to recognize common electrolyte imbalances in a timely manner in order to administer appropriate therapy and achieve better outcomes

Hence, aim of this study was to study the occurrence of hyponatremia in children suffering from severe pneumonia.

This present prospective cross-sectional study was carried out in Paediatric Ward (SNM) and PICU of Burdwan Medical College and Hospital, Burdwan, West Bengal, India between November 2019 to August 2021.

Study population and sampling technique : Children aged between 1-5 years, diagnosed to have severe pneumonia admitted in SNM of Burdwan Medical College and Hospital between 1st January 2020 to 31st December 2020 were enrolled for the present study.

Inclusion criteria : Children aged between 1-5 years with severe pneumonia admitted in SNM ward and PICU at Burdwan Medical College and Hospital. Criteria for selection of cases of severe pneumonia- Tachypnoea, Chest Indrawing, Nasal Flaring, Cyanosis, Granting etc.

Exclusion criteria : Children with evidence and diagnosed case of CHD. Associated congenital lung anomaly. Gross neurodeficit (like CP) or, condition like scoliosis, kyphosis where the normal respiratory pattern is different. Diagnosed case of CRF, Nephrotic Syndrome and endocrine disorders. Patients of uncooperative mothers.

Data Collection: This study was carried out in children aged between 1-5 years. The cases of severe pneumonia were studied, and cases confirmed by clinical examination like- tachypnoea, chest indrawing, nasal flaring, cyanosis, grunting, unable to feed etc. Written consent was taken from the parents. All cases were evaluated using the following variables like age, sex, tachypnoea, CRP, total leucocyte count.

Participants of the study were chosen randomly from those who were hospitalized from 1st January 2020 to 31st December 2020. Information on sociodemographic variables including child age and gender and also clinical features of severe pneumonia; such as the presence and duration of fever, cough, nasal congestion, thoracic and abdominal pain and duration of hospitalization also recorded. Moreover, laboratory examination, including nonspecific markers of inflammation, such as WBC, ESR, CRP and also biochemical examination like electrolytes like sodium, potassium were performed in order to find possible predictors of pneumonia severity and outcome. Moreover laboratory examinations were done at the admission of the child to the hospital, irrespective of the time of admission.

Data Analysis plan- Data was analyzed using Statistical Package for Social Sciences, version 21 (SPSS). Results for continuous variables are presented as mean and standard deviation, whereas results for categorical variables are presented as frequency and percentage. All parametric data was analyzed using Student’s t-test. All non-parametric data was analysed by Chi-square test. A p-value of <0.05 was considered statistically significant.

Table 1: Age and gender wise distribution of the study population (n=141)

A total of 141 cases of severe pneumonia were selected for the present study. Patients were aged between 12 to 60 months. The most common age group was 12-24 months involving 41.1% (58) cases followed by 37-48 months (24.8%). The mean age of the study participants was 32.21 ±13.67 months. In the present study we observed a male preponderance with 63.8% male participants and 36.2% female participants. (Table 1)

Table 2: Clinical Presentation and Complications seen along with Pneumonia (n=141)

Difficulty breathing, high respiratory rate and chest retraction was present in all cases (100%). The other manifestations were chest pain (28.4%), nasal congestion (26.2%) and fever (16.3%). Majority of the study subjects had no additional complication (74.5%) while 12.8% had pneumothorax, 8.5% had pleural effusion and 4.3% had empyema. (Table 2)

Table 3: Finding of different counts

Majority of the study subjects had TLC count between8000- 11000 cu/mm (58.2%) while 29.8% had TLC count between 4000-8000 cu/mm and 12% had TLC count >11000 cu/mm. In the present study acute phase reactants CRP was positive in 86.5% of the children. In the present study a low level of serum sodium level was observed in 45 (31.9%) patients. Hence the prevalence of hyponatremia in the present study was 31.9%. Majority of them had moderate hyponatremia (60%), while 33.3% had mild hyponatremia and 6.7% had severe hyponatremia. (Table 3)

 Table 4: Association of Age with grading of Hyponatremia

The above observation suggests that young children are more prone to develop severe hyponatremia. (Table 4)

Table 5: Association of Sex with grading of Hyponatremia

Above analysis we found there was no significant association between severity of hyponatremia and gender suggesting no particular gender is significantly associated with severity of hyponatremia (p value = 0.922). (Table 5)

Table 6: Association of Total Leukocyte Count with grading of Hyponatremia

Above analysis we found there was a significant association between TLC level and severity of hyponatremia. This observation suggests that the level of TLC increases with increasing grade of hyponatremia (p value = <0.0001. (Table 6)

Table 7: Association of CRP with grading of Hyponatremia

The observation of the present study suggests that CRP is significantly associated with severity of hyponatremia as CRP positivity was significantly high among patients with hyponatremia with normonatremia (p value = 0.05). (Table 7)

Table 8: Association of various parameters with grading of Hyponatremia.

The observation of the present study reveals that serum sodium level decreases significantly with increasing grades oh hyponatremia (p value = <0.0001). on the other hand mean ESR level, mean body temperature at admission, time for defervescence, duration of oxygen requirements, duration of tachypnoea and duration of hospital stay significantly increases with increasing grade of hyponatremia. (Table 8)

Pneumonia is one of the leading causes of mortality in childhood and it cause death of 19 % (2 million) of children under 5 years age. If we add neonatal period to this the overall death estimate will increase to 29 %. Pneumonia affects every region of the world but its prevalence is mostly seen in South Asia and sub-Saharan Africa where it cause 85% of deaths.⁹

In the present study majority of the children with severe pneumonia are aged less than 2 years (41.1%). This is understandable, as in usual practice, we tend to find pneumonia cases more in younger age group patients. In the present study we observed a male preponderance with 63.8% male participants and 36.2% female participants.

This distribution is similar to studies done by Mandal et al. and Duru et al. showing 62 % and 57 % males respectively in their studies.^10,11 Praneetha CK et al. in their study reported Among 122 children included in the study, 73 were males (60%) and 49 (40%) were females.¹² The role of sex as a risk factor for Community Acquired Pneumonia (CAP) remains unclear, and no consensus has been reached in the literature. Males are more likely to develop lower respiratory tract infections.

In the present study majority of the study subjects had no additional complication (74.5%) while 12.8% had pneumothorax, 8.5% had pleural effusion and 4.3% had empyema. In a study conducted by Rabia A. Ahmed, Thomas J. Marrie, Jane Q. Huang, on patients of CAP a diagnosis of empyema was made in 47 patients (1.3%) by the attending physician; 24 patients (0.7%) met criteria for definite cases. The in-hospital mortality rate for patients with definite empyema was 4.2%.¹²

In the present study out of 141 cases with severe pneumonia we found 45 had hyponatremia. Hence the prevalence of hyponatremia in the present study was 31.9% and was comparable with some studies done in India where the frequency was 27- 31%.^13,14

This was similar to the result obtained by the study conducted by Singhi and Dhawan et al, in 1989 where hyponatremia was seen in 27% and hypernatremia in 3.7%.^15,16 Till date only few studies exist which concern with the correlation of hyponatremia and pneumonia in children. It was first described by Stormont and Waterhouse in 1962.¹⁷

Out of 45 cases of hyponatremia majority of them had moderate hyponatremia (60%), while 33.3% had mild hyponatremia and 6.7% had severe hyponatremia This findings are close to the study conducted by Afroditi Sakellaropoulou et al. in 2008 on 54 patients where 33.33% of children had mild hypo-natremia and 1 child (1.90%) had moderate hyponatremia.¹⁸

The Hyponatremic (mild, moderate and severe) and the normonatremic (NN) group were compared by statistical analysis. Age and sex had no correlation with hyponatremia in our study. This was comparable to study by Don M in age, gender or body weight.¹⁹

Patients of HN group had higher initial body temperature similar to another study.¹⁹ In our study all the clinical parameters taken to assess the severity of pneumonia, were significantly longer in the Hyponatremic group. On admission HN group had higher- body temperature, mean duration of tachypnoea, time for defervescence, greater length of hospital stay, longer duration of oxygen requirement.

Among the laboratory parameters studied by us e.g.- Mean ESR, CRP value, WBC Count, Neutrophil proportion, taken as surrogate marker of severity of illness, were significantly higher in HN group.

Don M also found higher white blood cell count, neutrophil percentage, serum C-reactive protein and serum procalcitonin in hyponatremic patients on admission.¹⁹ Nair et al. showed higher white blood cell count in the hyponatremic group.²⁰

Recently, few studies are being done to find out the exact cause of hyponatremia in community acquired pneumonia. Swart RM et al. in their article on hyponatremia and inflammation mentioned data supporting a role in the non osmotic release of vasopressin and thought that this mechanism may play role in clinically significant forms of hyponatremia.²⁰

However, whatever is the cause of hyponatremia in community acquired pneumonia, various studies including the present study have consistently shown hyponatremia being a common electrolyte imbalance in community acquired pneumonia and is associated with severe illness and increase in the morbidity and mortality. The major limitation of the present study was the cause of hyponatremia in pneumonia not studied.

Hyponatremia is prevalent in children with pneumonia. The children admitted with pneumonia have higher morbidity when associated with hyponatremia. In our study too hyponatremia was detected in children with pneumonia that was statistically significant. Estimation of serum sodium, plasma and urine osmolality with urinary sodium level is necessary to manage a case of Severe Pneumonia on account of the deleterious effect that hyponatremia has on the overall outcome.

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