Snapshot A 55-year-old alcoholic man presents to the emergency department acutely altered. Upon initial workup it is noted that the patient has a Glasgow coma scale of 7 and is hypoxic and hypercapneic. He is subsequently intubated and mechanically ventilated. Secondary exam reveals a patient covered in vomit and urine who smells like alcohol. (Acute respiratory distress syndrome). Introduction Clinical definition a ventilator that mechanically oxygenates/ventilates the patients with settings determined by the physician Therapeutic indications for intubation and mechanical ventilation include failure to oxygenate failure to ventilate inability to protect airway GCS < 8 (less than 8, intubate) suspected clinical course requiring intubation and ventilation Main modes assist-control (volume-cycled or pressure-targeted) volume cycled settings: tidal volume (TV), flow rate, flow waveform, fraction of inspired oxygent (FiO2), positive end-expiratory pressure (PEEP), and frequency airway pressures and auto-PEEP are dependent on respiratory system pressure-targeted settings: pressure target, inspiratory time, inspiratory rise rate, FiO2, PEEP, and frequency tidal volume and auto-PEEP are dependent upon respiratory system pressure-support ventilation usually with set continuous positive airway pressure (CPAP) spontaneous mode where support can be adjusted cannot set frequency or tidal volume these are dependent upon patient effort, strength, and compliance of respiratory system tolerated well because flow, depth, and length are all patient controlled synchronized intermittent mechanical ventilation (SIMV) combination of spontaneous breathing and set number of ventilator breaths that are fully supported but coincide with spontaneous efforts Complications Cardiovascular impairment positive intrathoracic pressure can decrease venous return, decreasing cardiac output Barotrauma (trauma from high pressures) findings subcutaneous emphysema pneumomediastinum pneumothorax pneumoperitoneum interstitial emphysema etiologies high mean alveolar pressure high peak airway pressures necrotizing lung pathology high minute ventilation longer duration of mechanical ventilation Ventilator-induced lung injury (atelectrauma or trauma caused by atelectasis) PEEP to prevent widespread alveolar unit closure and atelectasis Acid-base status derangements generally, changing the respiratory rate is preferred for responding to derangements (because TV is based on height) increase respiratory rate metabolic acidosis respiratory acidosis decrease respiratory rate (assuming adequate oxygenation) respiratory alkalosis Infections ventilator-associated pneumonia broader antibiotic coverage for Staphylococcus aureus, Pseudomonas aeruginosa, and other gram-negative bacilli P. aeruginosa: cefepime, piperacillin-tazobactam, and imipenem/meropenem Expanded gram-negative coverage: aminoglycosides MRSA: vancomycin, linezolid daptomycin cannot be used because it is inactivated by surfactant in the respiratory tract