Intro to RT exam 3

What does IPAP stand for?

Inspiratory Positive Airway Pressure — the HIGH pressure setting during NIPPV/BiPAP

What does EPAP stand for?

Expiratory Positive Airway Pressure — the LOW pressure setting during NIPPV/BiPAP

What is the formula for Pressure Support?

Pressure Support = IPAP − EPAP (the difference between the two pressures drives ventilation/Vt)

A larger pressure support gap means what?

Greater ventilation — larger tidal volume (Vt) and higher minute ventilation (Ve)

What does EPAP primarily control?

Oxygenation — it functions similarly to PEEP

What does Pressure Support (IPAP−EPAP) primarily control?

Ventilation — it affects tidal volume and CO₂ elimination

To improve oxygenation WITHOUT changing pressure support, what do you do?

Raise EPAP AND raise IPAP by the same amount. Example: 10/5 → 12/7 (PS stays at 5)

To improve ventilation WITHOUT changing oxygenation, what do you do?

Raise IPAP only, keeping EPAP the same. Example: 10/5 → 12/5 (PS increases from 5 to 7)

To improve BOTH oxygenation and ventilation, what do you do?

Raise IPAP more than EPAP. Example: 10/5 → 14/7 (PS increases from 5 to 7, EPAP increases for O₂)

What does a high HCO₃ on an ABG almost always indicate?

COPD patient (chronic CO₂ retainer). Do NOT blow off CO₂ too aggressively — risk of alkalosis.

What is the SpO₂ target for CO₂ retainers (COPD)?

88–92% (NOT the standard 95%+ target)

When should EPAP be used as the secondary oxygenation tool?

When FIO₂ is already at 60% and the patient is still hypoxic (refractory hypoxemia)

What are the 3 main indications for CPAP?

1) Hypoxemic respiratory failure (atelectasis/airway collapse), 2) Acute cardiogenic pulmonary edema (CHF), 3) Obstructive sleep apnea (OSA)

What are the main indications for NIPPV/BiPAP?

1) Hypercapnic respiratory failure (↑ CO₂), 2) Hypoxemic failure with increased WOB despite O₂, 3) Post-extubation bridge, 4) DNI patients needing temporary support

What does ST mode stand for in BiPAP?

Spontaneous/Timed — S = patient triggers breaths; T = machine delivers backup breath if patient doesn't breathe within the set interval

For BiPAP to work, what must the patient be doing?

Spontaneously breathing — the backup rate is ONLY a backup, not the primary trigger

What is the maximum acceptable leak on NIPPV?

Less than 50 L/min

What are the NIPPV alarm settings for respiratory rate?

High: 10–15 above total RR | Low: 5–10 below total RR

What are the NIPPV alarm settings for PIP (peak inspiratory pressure)?

High: 10–15 above PIP | Low: 5–10 below PIP

What are the NIPPV alarm settings for tidal volume (Vt)?

High: 100 mL above Vt | Low: 100 mL below Vt

What are the NIPPV alarm settings for minute ventilation (Ve)?

High: 2 L above Ve | Low: 2 L below Ve

What is the apnea/LIPt alarm setting?

20 seconds

What do you do if PIP is 26 and you need to set a high pressure alarm?

26 + 15 = 41 cmH₂O (within the 10–15 above range)

What can a low Vt or low Ve alarm indicate?

Mask leak beyond what the machine can compensate, or decreased lung compliance

What is the CPAP pressure range?

5–20 cmH₂O. Above 20 risks gastric insufflation.

How do you wean CPAP?

Decrease in increments of 1–2 cmH₂O down to 5 cmH₂O, then discontinue and switch to conventional O₂ therapy

What is the IPAP range for NIPPV?

10–20 cmH₂O. IPAP must always be 5+ cmH₂O above EPAP. Above 20 risks gastric insufflation.

What is the EPAP range for NIPPV?

5–15 cmH₂O

What does HFNC stand for and what are its other names?

High-Flow Nasal Cannula — also called HHFNC, HHF (Heated High Flow), HFOT (High-Flow Oxygen Therapy), HOT

Does HFNC increase tidal volume?

No — HFNC washes out CO₂ from anatomic dead space but does NOT add tidal volume

What is the HFNC PEEP-like rule of thumb?

Every 10 L/min of flow ≈ 1 cmH₂O of PEEP-like effect

What is the flow range for HFNC?

20–60 L/min. Start lower until patient is comfortable, then titrate up.

How do you wean HFNC?

Reduce flow by 5–10 L/min increments; when at ~20 L/min, transition to conventional nasal cannula

Patient has inspiratory crackles. Do you give a bronchodilator?

NO. Crackles = fluid or secretions → think suction or Lasix (furosemide), NOT a bronchodilator

Patient has expiratory AND/OR inspiratory wheezing. What do you give?

A bronchodilator (e.g., albuterol/levalbuterol)

Name 5 absolute contraindications to NIV

Apnea/cardiopulmonary arrest, facial burns, facial/cranial trauma, inability to protect airway/vomiting, need for immediate intubation, hemodynamic instability/arrhythmias, severe epistaxis, severe respiratory acidosis (pH <7.20), upper GI bleeding, fixed upper airway obstruction

Name 4 relative contraindications to NIV

Anxiety/claustrophobia, inability to tolerate mask interface (dementia), bowel obstruction, copious secretions, inability to clear secretions

What are the complications of NIPPV?

Aspiration, hypotension (cardiac embarrassment from high pressures), pneumothorax, uncontrolled leaks, dry upper airway, gastric distension, skin breakdown (especially bridge of nose)

What is "cardiac embarrassment" in the context of NIPPV?

Hypotension and/or tachycardia caused by high positive pressures reducing venous return and cardiac output — always monitor BP and HR

What does a low minute ventilation alarm most likely indicate on NIPPV?

Potential leak around the mask

What does a drug overdose patient with high CO₂ and low O₂ have in common with a COPD patient?

Both have hypercapnic + hypoxic respiratory failure, but the cause is different. Drug OD = respiratory muscle suppression. Management differs — OD patients may need intubation if airway unprotected.

What is Kussmaul breathing and what causes it?

Deep, rapid breathing seen in DKA — the body compensates for metabolic acidosis by blowing off CO₂ (an acid)

What is the formula to target a desired FIO₂ based on PaO₂?

PaO₂ / FIO₂ = constant ratio. Use current PaO₂/FIO₂ to solve for desired FIO₂ when targeting a specific PaO₂.

When should you NOT use BiPAP for a drug overdose patient?

If the patient cannot protect their airway, has a depressed gag reflex, or is at risk of vomiting → intubate instead

What does "ventilation first" mean?

Oxygenation is meaningless without ventilation. Always ensure the patient is ventilating (moving CO₂) before focusing on oxygenation.

What are signs that NIPPV is working (signs of improvement)?

Decreased RR, decreased WOB, decreased HR/BP, improved SpO₂/PaO₂, improved pH, decreased CO₂, improved dyspnea

What does it mean if a patient on NIPPV is NOT improving within a reasonable time?

Consider need for invasive ventilation (intubation)

What is the most common mask interface used in acute care for NIPPV?

Full face mask (covers mouth and nose) — nasal masks are less effective when patients breathe through their mouth

What is a slight mask leak during NIPPV?

Normal and actually desired — machines are designed to compensate for a small amount of leak; problems arise when leak exceeds 50 L/min

Air trapping is noted on the V60. What are two ways to address it?

1) Decrease pressure support (smaller Vt = less time to deliver), 2) Decrease I-time. NOTE: you cannot increase flow rate on the V60 — there is no flow button.

NIPPV initial example: settings 10/5. What is the pressure support?

PS = 10 − 5 = 5 cmH₂O

NIPPV example: you change settings from 10/5 to 14/5. What happened to PS and why?

PS increased from 5 to 9. IPAP went up while EPAP stayed the same → more ventilation (higher Vt)

NIPPV example: you change settings from 10/5 to 12/7. What happened to PS and why?

PS stayed the same (12−7=5). Both IPAP and EPAP raised equally → improved oxygenation without changing ventilation