Overview

Mechanical ventilation delivers positive-pressure breaths through an endotracheal or tracheostomy tube when a client cannot maintain adequate gas exchange. Three NCLEX modes: Assist-Control (AC) gives the full set tidal volume to every breath the client triggers or at the set rate, risking respiratory alkalosis if tachypneic; SIMV gives mandatory breaths at a set rate but lets spontaneous breaths run at the client's own volume (useful for weaning); Pressure Support (PS) boosts each client-initiated breath with preset pressure and sets no mandatory rate (weaning / intact drive). Master one rule: FiO2 fixes oxygenation, rate and tidal volume fix CO2.

Indications

respiratory failure

inadequate gas exchange

acute hypoxemic respiratory failure

e.g. ARDS

inability to protect airway

COPD exacerbation with hypercapnia

alert client -> trial BiPAP first

During — Monitoring

The nurse monitors the core settings and titrates oxygen to target. FiO2 starts high then titrates down to keep SpO2 at or above 94% (88-92% for chronic CO2 retainers).

goal >= 94%

hypoxemic

CO2 retainer target

standard target

100

% SpO2

Interpretation

Ventilator alarms split into two pressure categories pointing in opposite directions: high pressure = something blocking outflow; low pressure = air escaping or not arriving. Assess the client first, then the equipment.

High-pressure vs low-pressure alarm

High-pressure alarmLow-pressure alarm

ProblemObstruction / resistanceLeak / disconnection

Typical causesSecretions, kink, biting, bronchospasmDisconnect, cuff leak, extubation

First nurse actionAssess client, then suction / unkink / repositionCheck connections + client, bag-valve-mask if extubated

Memory hookBlocked -> grab suctionLoose -> grab the bag

High-pressure alarm

Problem: Obstruction / resistance
Typical causes: Secretions, kink, biting, bronchospasm
First nurse action: Assess client, then suction / unkink / reposition
Memory hook: Blocked -> grab suction

Low-pressure alarm

Problem: Leak / disconnection
Typical causes: Disconnect, cuff leak, extubation
First nurse action: Check connections + client, bag-valve-mask if extubated
Memory hook: Loose -> grab the bag

Technique

High-pressure alarm: work simple to complex, client first.

After — Complications

barotrauma

ventilator-associated pneumonia

keep HOB 30-45 degrees

atelectasis

respiratory alkalosis

AC mode with tachypnea

PEEP-induced hypotension

high PEEP reduces venous return / cardiac output

post-extubation laryngeal edema

respiratory muscle fatigue

failed spontaneous breathing trial

Patient Teaching

inflated cuff prevents speech

provide communication board or writing pad

explain alarms are expected

reassure to reduce anxiety

weaning readiness signs

alert, stable, low PEEP/FiO2, cause resolving

Report Nowescalate immediately

tension pneumothorax Hallmark

absent unilateral breath sounds, tracheal deviation away, JVD; needs needle decompression

tracheal deviation Hallmark

absent unilateral breath sounds

subcutaneous emphysema

accidental extubation

bag-valve-mask, call for help

circuit disconnection

post-extubation inspiratory stridor

laryngeal edema; ready for reintubation

rapidly falling SpO2 with cyanosis

disconnect vent, manually ventilate with 100% O2

new hypotension after PEEP increase

spontaneous breathing trial failure

RR > 35, HR change > 20%, accessory/paradoxical breathing -> resume full support

Clinical Pearl

FiO2 fixes O2, rate fixes CO2 - and when an alarm screams, assess the client before the machine: block grabs suction, leak grabs the bag.