Community-acquired pneumonia (CAP) is an inflammation of the infected lung parenchyma (including the alveolar wall, i.e., the interstitial lung in the broad sense) that occurs outside the hospital, including pneumonia that develops within an average incubation period after hospital admission due to a pathogenic infection with a defined incubation period.
I. Clinical diagnosis of CAP based on
1, Newly developed cough and sputum, or aggravation of symptoms of pre-existing respiratory disease with purulent sputum; with or without chest pain.
2, fever ≥ 38 degrees.
3, Solid lung signs and/or wet rales.
4, WBC>10×10^9/L or <4×10^9/L with or without left shift of nucleus.
5, Chest X-ray shows lamellar or patchy infiltrative shadows or interstitial changes with or without pleural effusion.
The clinical diagnosis can be established by any of the above items 1 to 4 plus item 5, and excluding tuberculosis, lung tumor, non-infectious interstitial lung disease, pulmonary edema, pulmonary atelectasis, pulmonary embolism, pulmonary eosinophilic infiltrates, and pulmonary vasculitis.
After the diagnosis is established, a rapid and accurate assessment of the condition is needed to decide whether to admit to hospital depending on its severity.
Evaluation of the severity of CAP
The presence of one of the following conditions, especially the coexistence of two conditions, often indicates the severity of the disease or the presence of risk factors for exacerbation of pneumonia, and hospitalization is recommended if conditions permit.
1. Age >65 years.
2, presence of underlying disease and related factors: chronic obstructive pulmonary disease, diabetes mellitus, chronic cardiac or renal insufficiency; inhalation or aspiration-prone factors; history of hospitalization for CAP within the last 1 year; altered mental status; post-splenectomy status; chronic alcoholism or malnutrition, etc.
3, abnormal signs: respiratory rate > 30 times/min; pulse ≥ 120 times/min; blood pressure < 90/60 mmHg; body temperature ≥ 40°C or < 35°C; impaired consciousness; presence of extra-pulmonary infectious lesions such as sepsis, meningitis.
4. Laboratory and imaging abnormalities. Blood routine: WBC>20×10^9/L, or <4×10^9/L, or neutrophil count<1×10^9/L; PaO2<60mmHg, PaO2/FiO2<300 or PaCO2>50mmHg when breathing air; blood creatinine (Scr)>106μmol/L or blood urea nitrogen (BUN)>7.1mmol/L; Hb<90g/L or erythrocyte pressure product (HCT) <30%; plasma albumin <2.5g/L; evidence of sepsis or diffuse intravascular coagulation (DIC). For example, positive blood cultures, metabolic acidosis, prolonged prothrombin time (PT) and partial thromboplastin time (PTT), thrombocytopenia; x-ray chest lesions involving more than one lobe of the lung, cavitation, rapid spread of lesions, or the presence of pleural effusion.
The following conditions are mostly manifestations of severe pneumonia, suggesting possible respiratory failure, pulmonary encephalopathy, circulatory disorders, renal failure, systemic inflammatory response syndrome and other conditions, which need to be closely observed and actively treated.
1, Impaired consciousness.
2, Respiratory rate >30 times/min.
3.PaO2<60 mmHg, PaO2/FiO2<300, need to carry out mechanical ventilation treatment.
4.Blood pressure <90/60 mmHg.
5, chest X-ray shows bilateral or multi-lobe lung involvement, or lesion enlargement ≥ 50% within 48 hours of admission.
6, oliguria: urine volume <20ml/h, or <80ml/4h, or acute renal failure requiring dialysis treatment.
Third, the choice of antibiotics
Due to the influence of various factors, mainly the irrational application of antibiotics, resulting in the emergence of a large number of drug-resistant strains of community-acquired pneumonia, so that the treatment faces difficulties, so repeatedly revised and updated treatment guidelines at home and abroad, comprehensive evaluation of the disease and determine the treatment guidelines, to avoid the confusion of empirical treatment of medication, to correct the phenomenon of excessive and inappropriate use of drugs, to reduce the pressure of antibiotic selection, to prevent drug resistance, improve the prognosis and save The following are some of the most important factors that should be considered
Empirical treatment: In the early stages of the disease, when pathogenic evidence is not yet available, empirical treatment is required, and the principles of antibiotic selection are: early, effective, full course, and adequate dosage, taking into account the side effects of antibiotics.
Community-acquired pneumonia has a broad spectrum of pathogens, and according to large-scale clinical studies, it is confirmed that Streptococcus pneumoniae, Mycoplasma, Chlamydia, and Haemophilus influenzae are still the bacteria with the highest detection rates. Therefore, the clinical selection of drugs is often preferred to antibiotics that can comprehensively cover the pathogenic bacteria, in order to control the symptoms as soon as possible, shorten the course of treatment, and reduce the side effects and organ damage caused by the long-term application of antibiotics.
It is often chosen β-lactams combined with macrolides, and studies have shown that fluoroquinolones alone can achieve the same effect as the combination of the above two drugs. Clinically, according to the patient’s age (quinolones are contraindicated in patients under 16 years of age), underlying disease (previous illness, with structural changes in the lung, such as bronchial dilatation of patients often combined with Pseudomonas aeruginosa, etc.), previous drug use, sensitivity, tolerance Select as appropriate.
If conventional treatment is ineffective for 3-5 days, consider changing antibiotics. The detection rate of Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli spp. is increasing, especially in patients with severe pneumonia, where Streptococcus pneumoniae, aerobic gram-negative bacilli, Legionella pneumophila, Mycoplasma pneumoniae, respiratory viruses, and Haemophilus influenzae are common causative agents. For this situation, a timely switch to sensitive antibiotics should be made in conjunction with drug sensitivity testing and a combination of the patient’s own factors.
Note that patients with severe pneumonia are often in a hypermetabolic state, and nutritional support is very important. The nutritional state of the organism is the basis for ensuring effective drug metabolism. Organ support is key. As the disease progresses to the stage of systemic inflammatory response, all organs will be damaged and timely symptomatic management will have a positive impact on the prognosis.
In patients with atypical symptoms of community-acquired pneumonia, slow progression of the disease, late detection, and already formed mechanistic changes, appropriate application of blood-activating drugs can promote the absorption of the lesions, prevent the formation of permanent local damage, and restore their normal function as much as possible.
The high incidence of community-acquired pneumonia, the expanding spectrum of pathogenic bacteria and the emergence of more and more drug-resistant strains pose certain difficulties for clinical treatment, and the increasing number of patients with severe pneumonia due to such changes require us to apply antibiotics appropriately to improve the success rate of early empirical treatment, shorten the course of the disease and improve the prognosis.
We remind everyone to seek timely medical consultation and regular treatment.