Pediatric acute infectious laryngitis is a diffuse inflammation of the mucous membrane of the larynx caused by viral or bacterial infections, most often occurring in the lower part of the vocal cords, mostly in the spring and winter, and commonly in children aged 1 to 3 years. The disease starts rapidly, progresses rapidly, and is easily complicated by laryngeal obstruction causing asphyxia, which can be life-threatening if not treated properly. This article provides a brief introduction to the etiology, clinical manifestations, laboratory tests, diagnosis and differential diagnosis and treatment of pediatric acute infectious laryngitis.
1. Etiology
The most common cause of pediatric acute infectious laryngitis is a viral infection of the upper respiratory tract, often followed by a bacterial infection on top of the viral infection. Common viruses include parainfluenza virus, influenza virus and adenovirus, and common bacteria include Staphylococcus aureus, Streptococcus and Streptococcus pneumoniae. The anatomical characteristics of the larynx in children are also an important factor in their susceptibility to acute infectious laryngitis: the laryngeal cavity in children is narrower and longer than in adults, with the narrowest part at the vocal cords, measuring only l4-15 mm in cross section;
The laryngeal cartilage is underdeveloped and weak, the larynx and vocal cords are rich in blood vessels and lymph nodes in the mucosa, and the submucosa is loose, which can easily cause congestion and edema. Since the immune organs of children are not yet mature, their resistance to infection and immunity are lower than those of adults, and the inflammatory response to laryngeal infection is severe. The coughing function of children is not strong, resulting in secretions not easily discharged and easily blocking the respiratory tract.
2.Clinical manifestations
2.1 Symptoms
Children develop fever, hoarseness, barking cough and inspiratory laryngeal tinnitus after acute upper respiratory tract infection or acute infectious disease. Some children have sudden onset with severe loss of voice or hoarseness. In severe cases, inspiratory dyspnea may occur. Dyspnea often worsens at night because the laryngeal muscles are relaxed after sleep and secretions are easily trapped in the larynx, which stimulates laryngospasm. A small number of children have choking phenomenon, choking and coughing when breastfeeding or drinking water, choking and coughing when eating solid food is relatively light.
2.2 Physical signs
Children often show irritability, and in severe cases, they have dyspnea, nasal flapping, inspiratory trigeminal signs (soft tissue depression in the upper and lower sternum, supraclavicular fossa, and intercostal space), cyanosis and so on. On auscultation of the lungs, inspiratory laryngeal sounds and dry rales can be heard, and wet rales can be heard if there is inflammation of the lower respiratory tract. Direct or indirect laryngoscopy shows acute congestion of the laryngeal mucosa, marked redness and swelling of the subglottis mucosa, narrowing of the glottic fissure, and visible mucous secretions.
2.3 Laboratory tests and instrumental examinations
The peripheral blood leukocytes are mostly significantly elevated, the proportion of neutrophils is increased, and there may be left shift of the nucleus. Children with laryngeal obstruction of degree II or above are mostly associated with hypoxemia, and carbon dioxide retention may be present in degree III or above. x-ray chest examination may show different degrees of emphysema or pulmonary atelectasis, and peribronchial inflammation and thickened lung texture may also be seen. For pediatric acute laryngitis, laryngoscopy is not used as a routine diagnostic tool, but only when tracheal intubation or incision is performed, because surgical operation and local stimulation can aggravate hypoxia or induce laryngospasm.
3. Diagnosis and differential diagnosis
The onset of acute infectious laryngitis in children is sudden and has its special symptoms: hoarseness, laryngeal tinnitus, barking cough and inspiratory dyspnea, which are generally diagnosed without difficulty.
According to the severity of inspiratory dyspnea, laryngeal obstruction is divided into 4 degrees.
① Grade I laryngeal obstruction: the child is normal in quiet time, and inspiratory laryngeal whine and dyspnea appear only after activity, with clear respiratory sounds on lung auscultation; if combined with lower respiratory tract infection, retching and sputum sounds can be heard, and heart rate may not change.
② Ⅱ degree laryngeal obstruction: the child may also have laryngeal whine and inspiratory dyspnea in quiet time.
③m degree laryngeal obstruction: In addition to the symptoms of Ⅱ degree laryngeal obstruction, the child has paroxysmal irritability due to hypoxia, cyanosis of lips and fingers and toes, perioral whitening, or pallor, fear, sweating, significantly reduced or inaudible respiratory sounds on chest auscultation, and inaudible retching sounds, low blunted heart sounds, heart rate above 14o~16o beats/min.
④ Ⅳ degree laryngeal obstruction: the child has severe respiratory distress, gradually becomes exhausted, semi-comatose or lethargic state; because the child is unable to breathe, the performance is temporarily quiet, the trigeminal sign is also not obvious, but the face is pale or gray, at this time the respiratory sounds almost completely disappeared, only tracheal conduction sounds, heart rate or fast or slow, irregular, weak and extremely blunt heart sounds, if the misdiagnosis can lead to death. The disease should be distinguished from acute laryngobronchitis, bronchitis, laryngeal diphtheria, acute membranous laryngitis, laryngeal edema, laryngospasm, acute epiglottitis, laryngeal or tracheal foreign body and other infantile laryngeal obstruction.
4.Treatment
Acute infectious laryngitis in pediatric patients develops rapidly and is easily complicated by laryngeal obstruction; therefore, prompt treatment with antibacterial drugs and adrenocorticotropic hormones (hormones) is required to rapidly relieve symptoms.
4.1 General treatment
Monitor the child’s condition closely, monitor vital signs, cyanosis, respiratory distress and the degree of respiratory distress, and if necessary, use a vital signs monitor to monitor ECG, respiration, terminal SaO 2 and other indicators; keep the airway open, maintain the room temperature and humidity, and do not treat in a dry environment. If the body temperature is high, give physical or medication to lower the temperature. Eat liquid or semi-fluid easily digestible food, drink more water, and if necessary, give fluids to ensure sufficient fluid and heat supply. Give oxygen to those with cyanosis and respiratory distress.
4.2 Antibacterial drug treatment
Antimicrobial drug therapy is a symptomatic treatment for pediatric acute infectious laryngitis that cannot be ignored. Because dehydration will make the respiratory secretions of children sticky, sputum is more difficult to discharge, thus aggravating airway obstruction. Nebulized inhalation can be used for those with sticky and dry sputum. In rural primary care hospitals, steam inhalation can be used instead of nebulized inhalation, which can also relieve symptoms, but attention needs to be paid to the control of temperature, to prevent burns.
Commonly used empirical medications are penicillin, erythromycin or cephalosporin antibiotics, generally a single drug can be used, only in serious cases to consider the application of two kinds of antibacterial drugs in combination. Subsequently, sensitive antibacterial drugs can be selected according to the results of pharyngeal swab culture and drug sensitivity test.
4.3 Adrenocortical hormone therapy
Hormones have the effect of anti-inflammation and inhibition of metaplasia, and are effective in treating laryngitis, but the dosage should be large enough, otherwise it is not easy to work. There are two main methods of systemic and inhalation medication.
4.3.1 Systemic medication
All children with dyspnea with laryngeal obstruction of degree II or above are treated with hormones, such as prednisone, dexamethasone or hydrocortisone. For children with dyspnea with degree II laryngeal obstruction, prednisone 1 mg,/kg can be given orally every 4-6 hours. Generally, after 6-8 doses, symptoms such as laryngeal tinnitus and dyspnea can be relieved or disappeared.
For children with second-degree laryngeal obstruction, dexamethasone 2-5 mg can be injected intramuscularly and then prednisone can be given orally. For children with more severe obstruction, dexamethasone 2-5 mg (increase or decrease according to age) or hydrocortisone 5-10 mg/kg should be administered intravenously for 4-6 hours.
4.3.2 Inhalation therapy
Budesonide is commonly used, which has the effect of constricting microvessels, reducing the exudation of inflammation, reducing edema and capillary dilation, inhibiting the movement of inflammatory cells to the site of inflammation, preventing the release of allergic mediators and reducing the activity of various allergic mediators, etc. It can effectively clear respiratory inflammation. Its non-specific anti-inflammatory and anti-allergic strength is 20-30 times that of dexamethasone and 600 times that of hydrocortisone.
It is a more effective drug for the treatment of asthma and can also be used for the treatment of laryngitis, mainly for local treatment, with the advantages of high local drug concentration, rapid action and avoiding the systemic adverse effects of hormones. Studies have shown that inhaled budesonide is fast and effective in the treatment of acute infectious laryngitis in children, and can reduce the chance of tracheotomy.
4.4 Sedative drugs
Children with acute infectious laryngitis are more agitated due to respiratory distress and hypoxia, so sedative drugs are appropriate. Isopropazine orally or by injection, in addition to sedation, can also reduce laryngeal edema and laryngospasm, most children with good results. Chlorpromazine and morphine have the effect of inhibiting respiration and affect the degree of observing respiratory distress, so it is better not to use them in children with acute infectious laryngitis.
4.5 Direct laryngoscopic aspiration
In children with respiratory distress with Ⅲ degree laryngeal obstruction, due to poor cough reflex, secretions are often retained in the larynx or trachea, which can be aspirated under direct laryngoscopy to relieve mechanical obstruction and reduce laryngospasm caused by secretion stimulation, which can mostly relieve respiratory distress immediately. At the same time of direct laryngoscopy and aspiration, 1% ephedrine can be inhaled by spray to reduce swelling of the larynx and relieve respiratory distress. After aspiration, the change of condition should be closely observed and tracheotomy should be performed if necessary.
4.6 Other treatments
It has been reported that serum calcium in children with acute infectious laryngitis is significantly lower than that in healthy children, which is the main cause of laryngeal cartilage softening, so children with hypocalcemia should be given calcium supplements and vitamin D treatment if necessary; those with acidosis should be corrected promptly. Children with severe disease can be given blood or plasma transfusion, gammaglobulin, etc. to enhance supportive treatment. Acute infectious laryngitis belongs to the category of laryngeal rash in Chinese medicine, and treatment with Chinese medicine and acupuncture is also effective.