Acute Respiratory Failure, ARDS, and Mechanical Ventilation

Vocabulary flashcards detailing key terminology, physiological parameters, clinical manifestations, pharmacological agents, and mechanical ventilation modes for acute respiratory failure and ARDS.

Room Air Fraction of Inspired Oxygen ($\text{FiO}_2$)

The concentration of oxygen present in ambient room air, which is measured at $21\%$.

Partial Pressure of Arterial Oxygen ($\text{PaO}_2$)

The measurement of oxygen tension in arterial blood obtained through an arterial blood gas ($\text{ABG}$), reflecting the amount of oxygen bound to hemoglobin being transported to tissues.

Hypoxemia

A decrease of oxygen tension in arterial blood, characterized on an arterial blood gas by a $\text{PaO}_2$ value less than $60\,\text{mmHg}$.

Hypoxia

A condition in which there is inadequate oxygen delivery to bodily tissues, assessed clinically through altered mental status, capillary refill, and peripheral pulses.

Circumoral Cyanosis

A bluish discoloration surrounding the mouth and lips, presenting as a late sign of worsening hypoxemia and respiratory compromise.

Ventilatory Failure

A category of acute respiratory failure caused by mechanical air movement problems such as central nervous system depression, neuromuscular disorders, or musculoskeletal chest wall injuries.

Oxygenation Failure

A category of acute respiratory failure where air movement occurs but pulmonary gas exchange is impaired due to conditions such as pneumonia, pulmonary embolism, heart failure fluid overload, or ARDS.

Tidal Volume ($V_T$)

The specific volume of air delivered or inhaled during a single respiratory cycle, averaging around $500\,\text{mL}$ in a normal adult breath.

Positive End-Expiratory Pressure ($\text{PEEP}$)

The positive pressure maintained inside the lungs at the end of expiration to prevent alveolar collapse and preserve alveolar recruitment, standardly set at a minimum of $5\,\text{cm}\,\text{H}_2\text{O}$.

Colorimetric $\text{CO}_2$ Detector

A device placed on the hub of an endotracheal tube immediately after intubation that changes to yellow in the presence of carbon dioxide to verify placement in the trachea rather than the esophagus.

Carina

The anatomical bifurcation of the trachea into the primary bronchi, where an endotracheal tube tip must sit approximately $2\,\text{cm}$ above to prevent tracheal mucosal damage and necrosis.

Endotracheal Tube Cuff

The inflatable balloon near the distal tip of an endotracheal tube inflated to seal the airway and prevent oral and pharyngeal secretions from entering the lower airways and lungs.

Ventilator-Associated Pneumonia ($\text{VAP}$) Bundle

A cluster of preventive nursing interventions for intubated patients that includes oral care every $4\,\text{hours}$, repositioning every $2\,\text{hours}$, prophylactic $H_2$ blockers or proton-pump inhibitors, and deep vein thrombosis prophylaxis.

Richmond Agitation-Sedation Scale ($\text{RASS}$)

A standardized scoring tool used to evaluate and titrate agitation and sedation levels in mechanically ventilated patients, with common target ranges between $0$ and $-2$.

Acute Respiratory Distress Syndrome ($\text{ARDS}$)

A severe systemic inflammatory process of the lungs that causes diffuse alveolar damage, pulmonary edema, surfactant degradation, reduced compliance, and refractory hypoxemia not responsive to high concentrations of inspired oxygen.

Surfactant

A lipoprotein complex in the alveoli that reduces surface tension, prevents alveolar collapse upon exhalation, and maintains lung compliance.

Prone Positioning

An intervention for severe ARDS that positions the patient face down for $12$ to $18\,\text{hours}$ per cycle to redistribute pulmonary infiltrates, shift alveoli forward, and improve gas exchange.

RotoProne Bed

A specialized kinetic therapy bed engineered to automatically rotate and maintain critically ill, intubated patients in a prone position.

Propofol (Diprivan)

A short-acting intravenous lipid-based sedative-hypnotic with a half-life of $2$ to $3\,\text{minutes}$, requiring continuous mechanical ventilation and IV tubing changes every $12\,\text{hours}$.

Train-of-Four ($\text{TOF}$)

A peripheral nerve stimulation assessment providing four electrical impulses to evaluate the depth of neuromuscular blockade, typically titrated to achieve $2$ out of $4$ visible muscle twitches.

Assist-Control ($\text{AC}$) Mode

A mandatory ventilator mode delivering a preset tidal volume with every breath, applied both to machine-timed breaths and to spontaneous patient-triggered breaths.

Synchronized Intermittent Mandatory Ventilation ($\text{SIMV}$)

A ventilator mode that delivers a programmed rate and tidal volume for mandatory breaths while allowing the patient to take spontaneous breaths in between at their own tidal volume using pressure support.

Continuous Positive Airway Pressure ($\text{CPAP}$)

A spontaneous breathing mode in which the patient initiates and controls all breaths while the ventilator provides continuous positive airway pressure and pressure support to overcome circuit tubing resistance.

Airway Pressure Release Ventilation ($\text{APRV}$)

A specialized ventilator mode maintaining continuous high airway pressure to recruit alveoli and optimize oxygenation, paired with brief cyclic pressure releases to vent out carbon dioxide.

Ventilator High Pressure Alarm

An audible ventilator alert indicating resistance to airflow, commonly caused by bronchospasm, tubing kinks, biting on the tube, or mucus plugging.

Ventilator Low Pressure Alarm

An audible ventilator alert indicating that delivered airway pressures have dropped, typically caused by a circuit disconnection or an endotracheal tube cuff leak.