Hospital-acquired pneumonia

Ventilator-associated pneumonia is a new pulmonary infiltrate with clinical signs of infection developing more than 48 hours after endotracheal intubation, driven by gram-negative bacilli and Staphylococcus aureus; empiric antipseudomonal therapy is started immediately from a semiquantitative respiratory culture and paired with ventilator-bundle prevention.

Community-acquired pneumonia is a lower respiratory tract infection acquired outside the hospital that is diagnosed by a compatible clinical syndrome plus a new infiltrate on chest imaging, risk-stratified with CURB-65 or the Pneumonia Severity Index to guide site of care, and treated with empiric antibiotics chosen by site of care and comorbidity, escalating to cover MRSA or Pseudomonas aeruginosa when risk factors are present.

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection, identified by an acute rise in SOFA score of 2 points or more in a patient with known or suspected infection. Survival depends on recognizing the pattern early and completing the hour-1 bundle: lactate, blood cultures before antibiotics, broad-spectrum antibiotics such as cefepime 2 g IV every 8 hours, and 30 mL/kg crystalloid for hypotension or a lactate of 4 mmol/L or higher.

ARDS is acute (within 1 week), bilateral, non-cardiogenic hypoxemic respiratory failure from diffuse alveolar damage, diagnosed by the 2012 Berlin criteria and graded by the Pao2/Fio2 ratio. Management is lung-protective ventilation, PEEP titration, early prone positioning for severe disease, conservative fluid strategy, and treatment of the inciting insult.

Lung abscess is a necrotic, pus-filled cavity in the lung parenchyma, most often from aspiration of oropharyngeal anaerobes in a patient with impaired airway protection, diagnosed by a cavity with an air-fluid level on imaging and treated with prolonged anaerobe-covering antibiotics plus postural drainage.

Acute kidney injury is a sudden rise in serum creatinine or fall in urine output from prerenal, intrinsic, or postrenal causes, defined and staged by KDIGO criteria. Management targets the underlying cause, corrects volume and electrolyte derangements, and escalates to renal replacement therapy for refractory hyperkalemia, acidosis, volume overload, or uremia.

Pseudomonas aeruginosa is a nosocomial, opportunistic gram-negative bacillus that causes hot-tub folliculitis, malignant otitis externa, ventilator-associated pneumonia, febrile-neutropenia bacteremia with ecthyma gangrenosum, and device-associated infections. Empiric therapy requires an antipseudomonal agent and, in resistance-risk or unstable patients, double coverage until susceptibilities return.

An acute exacerbation of COPD is a change in baseline dyspnea, cough, or sputum that requires a change in therapy, most often triggered by viral or bacterial respiratory infection. Severity is graded by the treatment required, and management is a stepwise sequence of bronchodilators, glucocorticoids, targeted oxygen, and, when hypercapnic acidosis is present, noninvasive ventilation.

Legionella pneumophila is an intracellular, water-borne gram-negative bacillus causing severe community-acquired pneumonia with prominent gastrointestinal and hepatic features, confirmed by urinary antigen testing and treated with a macrolide or fluoroquinolone rather than a beta-lactam.

Delirium is an acute, fluctuating disturbance of attention and awareness caused by an underlying medical, toxic, or metabolic insult. Diagnosis rests on the Confusion Assessment Method; management is identification and treatment of the precipitating cause plus withdrawal of deliriogenic drugs, reserving antipsychotics for safety only.