Medical Surgical III: Mechanical Ventilation & Alarms

Flashcards covering mechanical ventilation principles, settings, modes, alarm causes, and extubation/weaning criteria from Medical Surgical III lecture notes.

What is the primary function of mechanical ventilation regarding treating underlying pulmonary conditions?

It is supportive only and not curative; it does not treat the underlying condition itself.

What arterial blood gas (ABG) criteria indicate acute respiratory failure requiring mechanical ventilation?

$\text{pH} < 7.25$ with $\text{pCO}_2 > 50\,\text{mmHg}$

What Glasgow Coma Scale (GCS) threshold indicates neurological dysfunction requiring mechanical ventilation?

$$\text{GCS} < 8$$

How does volume-cycled mechanical ventilation deliver breaths?

It delivers a predetermined tidal volume ($V_T$) with each inspiration, maintaining consistent volume from breath to breath while airway pressure varies.

What defines pressure-cycled ventilation?

The ventilator delivers air until a preset pressure is reached, at which point inspiration ends and the ventilator cycles off.

What mechanical ventilation cycling method is depicted in this flow waveform graph?

Flow-cycled ventilation (the ventilator cycles into expiration when inspiratory flow drops to a predetermined percentage of peak flow, such as $20\%$).

What are the two pressure levels delivered during Bilevel Positive Airway Pressure (BiPAP) therapy?

Inspiratory Positive Airway Pressure (IPAP/PS) and Expiratory Positive Airway Pressure (EPAP/PEEP).

What is the primary purpose of the Expiratory Positive Airway Pressure (EPAP) setting in BiPAP?

To keep the airways open and prevent airway collapse.

Why is Non-Invasive Positive Pressure Ventilation (NIPPV) contraindicated in obtunded patients?

Obtunded patients have depressed gag reflexes, creating a significant risk for aspiration.

Why is Continuous Positive Airway Pressure (CPAP) considered the most effective treatment for obstructive sleep apnea?

Continuous positive pressure acts as a splint to keep the upper airway and trachea open during sleep.

What is the standard baseline calculation for tidal volume ($V_T$) in a patient with normal lungs?

$6\text{--}8\,\text{mL/kg}$ (approximately $500\,\text{mL}$).

Why is a lower tidal volume setting of $4\text{--}6\,\text{mL/kg}$ used for patients with ARDS?

To ensure tolerance and prevent volutrauma, which could worsen ARDS.

How is baseline tidal volume adjusted for a $60\,\text{kg}$ patient to account for dead space?

Baseline tidal volume is $360\,\text{mL}$ ($6\,\text{mL/kg} \times 60\,\text{kg}$), plus an additional $100\,\text{mL}$ to accommodate dead space.

What are the normal Inspiratory to Expiratory (I:E) time durations for a normal $1:2$ ratio?

Inspiratory time is $0.8\text{--}1.4\,\text{seconds}$ and Expiratory time is $1.6\text{--}2.8\,\text{seconds}$.

How does excessive Positive End Expiratory Pressure (PEEP) decrease cardiac output?

Excessive PEEP increases intrathoracic pressure, leading to compression of the heart and a vasovagal response that results in poor cardiac output and hypotension.

What sensitivity settings are used for flow-triggered and pressure-triggered breaths?

Flow-triggered: $1\text{--}3\,\text{L/min}$; Pressure-triggered: $0.5\text{--}1.5\,\text{cm H}_2\text{O}$.

What is the defining characteristic of Controlled Mandatory Ventilation (CMV)?

Breaths are delivered at a preset rate and preset tidal volume ($V_T$) independent of the patient's ventilatory effort.

What complication can occur in Assist Control Ventilation (A/C) if a patient breathes rapidly?

Hyperventilation leading to respiratory alkalosis, because the machine forces full tidal volume breaths with every patient attempt.

Which ventilator mode is primarily used to wean patients from mechanical ventilation by synchronizing mandatory breaths with patient effort?

Synchronized Intermittent Mandatory Ventilation (SIMV).

According to this clinical algorithm, what is the immediate nursing intervention if a ventilated patient is in respiratory distress or hemodynamically unstable?

Remove the patient from the ventilator, manually resuscitate/ambubag with $100\%\,\text{O}_2$, and perform a rapid assessment.

How long after mechanical ventilation initiation can Ventilator-Associated Pneumonia (VAP) develop if secretions are not properly suctioned?

$$48\text{--}72\,\text{hours}$$

What are common causes of a High Pressure ventilator alarm?

Secretions in ETT, condensation in tubing, kinked tubing, biting the ETT, coughing/gagging, bronchospasm, or pneumothorax.

What are common causes of a Low Pressure ventilator alarm?

Disconnected ventilator tubing, air leaks, or a displaced ETT or tracheostomy tube.

How is an oral airway correctly measured prior to insertion?

From the victim's earlobe to the corner of the mouth.

What ventilator parameter targets indicate readiness for mechanical ventilation weaning or extubation?

$\text{FiO}_2 < 50\%$, $\text{PEEP} < 8\,\text{cm H}_2\text{O}$ (preferably $3\text{--}5\,\text{cm H}_2\text{O}$), $\text{PaO}_2 > 75\,\text{mmHg}$, and $\text{pH} > 7.25$.