Lower respiratory tract infection (LRTI) is infection below the level of the larynx and it includes bronchiolitis, pneumonia and empyema. It is inflammation of the airways/pulmonary tissue, commonly due to viral, bacterial or fungal infection(1).
ARIs are the major cause of mortality among children aged less than 5 years especially in developing countries. Worldwide, 1 million (16%) mortality among children aged less than 5 years is attributed to respiratory tract infections predominantly pneumonia associated. Southeast Asia stands first in number for ARI incidence accounting for more than 80% of all incidences together with sub-Saharan African countries(2, 3). Children with ARI account for 30% to 50% of the children attending outpatient clinics and 20% to 40% of admissions into hospitals(4).
According to Nepal demographic health survey 2016, prevalence of symptoms of ARI among children under age 5 in Nepal fell from 5% in 2011 to 2% in 2016. Prevalence of symptoms of ARI was the highest among children age 6-11 months and age 12-24 months (4% each), followed by children age 24-35 months (2%)(5).
LRTI comprises bronchiolitis, pneumonia and empyema. Bronchiolitis is one of the common childhood illness and Respiratory syncytial virus is the most common etiologic agent. Hospitalization due to bronchiolitis is required in approximately 1% of affected children, primarily because of associated dehydration, inadequate oral intake, or respiratory insufficiency. Among those admitted, 10-15% requires intensive care due to impending respiratory failure(6).
Pneumonia is a form of acute respiratory infection that affects the lungs Pneumonia is usually preceded by upper respiratory tract infection, which promote invasion of lower respiratory tract by virus, bacteria or other pathogens that trigger an immune response. (7).
Empyema is defined as collection of pus in pleural cavity. Common pathogens are Streptococcus pneumonia , Staphylococcus aureus and Streptococcus pyogenes. Empyema starts as moderate to large exudative parapneumonic effusion, which can progress to being loculated with further development of a fibrinous peel. This can be associated with fever, fast breathing and respiratory distress(8).
LRTI can be complicated as lung abscess, pneumatocele, pneumothorax, apnoea, hyperinflation, atelectasis, respiratory failure. Complications beside respiratory include sepsis, meningitis, pericarditis, endocarditis, osteomyelitis, septicarthritis, and electrolyte imbalance(9, 10).
Fluids and electrolytes are the main pillars in the maintenance of body homeostasis. Most important among electrolytes is sodium which is the abundant cation of the extracellular fluid. Hyponatremia is the most common electrolyte abnormality seen in the intensive care unit (ICU), with an incidence as high as 30% in some reports(11, 12).
Hyponatremia is defined as serum sodium (Na) concentration of less than 135mEq/L (9-10).A major consequence of hyponatremia is influx of water into the intracellular space, resulting in cellular swelling that can lead to cerebral edema and encephalopathy. The clinical manifestations of hyponatremia are primarily neurologic and related to cerebral edema caused by hypo- osmolality(13).
Hyponatremia associated with pediatric pneumonia is most commonly due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This syndrome is characterized by hyponatremia and hypo-osmolality. It results from the inappropriate and continued secretion and/or action of antidiuretic hormone despite normal or increased plasma volume (14, 15).
Hyponatremia associated with bronchiolitis is due to hyperinflation of lungs. Hyperinflation reduces blood flow to the right atrium and stimulates the release of vasopressin(AVP)from the posterior pituitary causing accumulation of intravascular fluid leading to dilutional hyponatremia(16,).
In a study done by Shingi S et.al to determine the frequency of electrolyte disturbance in pneumonia in 264 hospitalized children in chandigrah, India found hyponatremia in 71(27%) children with pneumonia. It was associated with two fold increase in complications and 3.5 times higher mortality(17).
Single-center retrospective cohort study was done in Children’s Hospital Colorado, USA comprising children age 1month to 2 years admitted to the PICU between January 2009 and April 2011. Study was done to characterize the relationship between hyponatremia and clinical outcome in bronchiolitis. One hundred and two children with bronchiolitis were enrolled. Twenty-three patients (22%) were diagnosed with hyponatremia. Mortality (13% vs 0%; P = .011), ventilator time (8.41 ± 2 days vs 4.11 ± 2 days; P = .001), duration of stay in the PICU (10.63 ± 2.5 days vs 5.82 ± 2.09 days; P = .007), and noninvasive ventilator support (65% vs 24%; P = .007) were significantly different between subjects with Hyponatremia than those without (18).
Acute respiratory tract infection is one of the serious health problems leading to hospitalization and mortality. In developing countries, 7 out of 10 deaths happen due to ARI in under 5-year age group(19).
Acute respiratory infection is classified by World Health Organization (WHO) as no pneumonia(child presenting as cough and cold), pneumonia(child with cough an fast breathing and or chest indrawing) and severe pneumonia or very severe disease( child with cough, fast breathing, chest indrawing and danger signs like unable to drink, convulsions, stridor)(20).
In Nepal, according to the most recent Annual Health Report by Department of Health Services (DOHS), in fiscal year 2073/74, a total of 1,810,722 ARI cases were registered, out of which 10.5% were categorized as pneumonia cases and 0.29% were severe pneumonia cases. The incidence of pneumonia at national level was 66 per 1000 under five children(21).
Pneumonia
Pneumonia is a form of acute respiratory infection that affects the lungs. (7). The physiological intrapulmonary shunting of de-oxygenated blood and ventilation perfusion mismatch following these pathological changes results in hypoxemia(22).
Causes of pneumonia in children are Bacteria- Escheriichia coli,Group B Streptococcus Listeria monocytogens in birth to 20days, Bacteria-Chlamydia trachomatis,Sterptococcus pneumonia Viruses Adenovirus,Influenza, Parainfluenza virus 1,2,3 from 3 weeks to 3 months, Bacteria-Chlamydia pneumonia,Mycoplasmapneumonia,Streptococcus pneumonia from 4 months to 5 years and from 5 years to adolescence Bacteria-Chlamydia pneumonia,Mycoplama pneumonia,Streptococcus pneumoniae(23) Etiology of Bronchiolitis(24):Respiratory syncital virus(50%cases), Rhinovirus, Adeno virus, Influenza, Parainfluenza, Human metapneumovirus, Human Bocavirus, Mycoplasma pneumoniae, Chlamydophila pneumonia, Chlamydophila trachomatis.
Bronchiolitis is a common cause of illness and is the leading cause of hospitalization in infants and young children. RSV infection is common in children older than two years(25).
Hypoxia, co-morbid condition such as diarrhea, age below 1 year, inability to feed, presence of loose stools and severe malnutrition are known factors for adverse outcome in children with lower respiratory tract infection. These factors increases duration of stay at hospital and if not managed properly can lead to death (26, 27).
Hyponatremia
Table 1: Severity of hyponatremia
Severity of Hyponatremia
|
Sodium(mEq/L)
|
Mild
|
131-135
|
Moderate
|
126-130
|
Severe
|
<125
|
Hyponatremia is defined as serum sodium (Na) concentration of less than 135 mEq/L. The effect of ADH on plasma osmolality depends on intact kidney function, which is required for appropriate retention or excretion of free water. (28).
SIADH syndrome is characterized by hyponatremia and hypoosmolality and results from the inappropriate and continued secretion and/or action of antidiuretic hormone despite normal or increased plasma volume presumably due to inflammatory cytokines, such as interleukin-6 (29), stress, and hypoxemia(30, 31). Hyperinflation of the lungs, a hallmark of the bronchiolitis, wheezing, reduces blood flow to the right atrium and stimulates the release of vasopressin(AVP)from the posterior pituitary causing accumulation of intravascular fluid leading to dilutional hyponatremia(32).
Pediatric Respiratory Severity Score (PRESS score)
This score was devised for a study done in National Hospital Organization Yokohama Medical center, an urban emergency hospital in Japan, in 2010-2011 to establish and examine the utility for assessing severity in children with respiratory symptoms (33).
The World Health Organization has suggested that children suspected of having infective illnesses and presenting not only with drowsiness, feeding difficulties, vomiting, convulsion but respiratory complains as dyspnoea should be hospitalized quickly(34). For calculating the score, objective signs such as respiratory rate, wheezing, retraction (accessory respiratory muscle use), SpO2, and feeding difficulties are assessed with each component given a score of 0 or 1, and total scores classified as mild (0–1), moderate (2–3), or severe (4–5). Using PRESS score, hospitalization rate was higher in moderate to severe cases and duration of oxygen therapy was significantly longer in severe cases compared with mild and moderate cases.
Table 2 : Pediatric Respiratory Severity Score ( PRESS ) (33)
Score component
|
Operational definition
|
0 or 1
|
Respiratory rate
|
Month
|
RR
|
|
< 12
|
>60
|
12- 36 months
|
>40
|
>36 months
|
> 30
|
Wheezing/ Crepitations
|
Based on auscultation
|
|
Accessory muscle use
|
Subcostal retraction, intercostal recession, suprasternal recession
|
|
Spo2
|
Less or more than 95 %
|
|
Feeding difficulties
|
Refusing feedings or not
|
|