Vents/ards

What does ventilation refer to? | Movement of air in and out of the lungs, not gas exchange or oxygenation.
Primary parameter to assess ventilation? | PaCO₂.
Effect of low CO₂ on cerebral vessels? | Causes vasoconstriction, may reduce ICP.
Risk of excessive hyperventilation? | Cerebral edema.
What is respiration? | Exchange of O₂ and CO₂ at the alveolar level.
What determines oxygenation? | Molecular O₂ absorption; influenced by FiO₂, Hgb, and diffusion barriers.
Indications for mechanical ventilation? | Respiratory failure, fatigue, refractory hypoxia, ↑ WOB, neuromuscular weakness, trauma, need for PEEP.
Main function of HFNC? | Provides heated, humidified O₂ with mild PEEP and dead-space washout.
Typical starting flow and max tolerated flow? | Start 30–40 L/min, titrate up to 60 L/min.
Starting FiO₂ and SpO₂ goal? | Start 100%, titrate to maintain SpO₂ > 90–92%.
Typical HFNC temperature setting? | 34–37 °C.
Best clinical use for HFNC? | Hypoxemic respiratory failure (pneumonia, COVID-19).
When to avoid HFNC? | Severe hypercapnia or altered mental status.
What does CPAP do? | Provides continuous pressure to keep alveoli open during inspiration and expiration.
What does BiPAP do? | Provides higher inspiratory and lower expiratory pressures to assist ventilation and oxygenation.
Indications for NIPPV? | Dyspnea, RR > 24, hypercapnia, hypoxemia, reversible failure (COPD, asthma, CHF, pneumonia, OSA, CF).
Contraindications for NIPPV? | Coma, arrest, shock, GI bleed, poor airway protection, secretion retention, AMS, anaphylaxis, obstruction.
Initial BiPAP settings for COPD/asthma? | 10/5 → 15/8 → 18/8.
Initial BiPAP settings for CHF? | 10/5 → 15/10 → 18/15 (↑ EPAP offloads LV).
Normal tidal volume? | 6 cc/kg ideal body weight.
Normal minute ventilation? | 6–7 L/min.
Common mask issues in NIPPV? | Facial/nasal pressure sores from tight seal — use breaks and dressings.
How to prevent gastric distention on NIPPV? | Keep peak inspiratory pressure < 25 cm H₂O.
When to avoid BiPAP due to aspiration risk? | During active vomiting or GI bleeding.
Mucosal dryness management? | Provide humidification and daily oral care.
Meds to improve NIPPV tolerance? | IV Precedex, Haldol, Ketamine, Fentanyl, Benzos.
CMV characteristics? | Delivers preset Vt + rate; no spontaneous breaths (paralyzed pts).
Assist-Control (AC) characteristics? | Delivers preset Vt at preset rate; patient-triggered breaths get full Vt.
SIMV characteristics? | Preset Vt + rate; allows spontaneous breaths without mandatory volume.
PSV characteristics? | Provides preset inspiratory assist; patient controls Vt + RR.
Pressure-Control (PCV) characteristics? | Set inspiratory pressure; Vt varies; improves comfort and alveolar filling.
APRV characteristics? | Alternates P-High (≤ 30 cm H₂O) and P-Low (0–5 cm H₂O); for refractory hypoxemia.
Minute ventilation formula? | VA = (Vt − VD) × f ≈ Vt × RR.
Example minute ventilation (0.5 L × 12)? | 6 L/min.
Main goal in COPD vent management? | Allow long exhalation to prevent air trapping.
Typical Vt and rate in COPD? | 8 mL/kg; RR ≈ 10 bpm.
I:E ratio for COPD vent? | 1:4 – 1:5.
PEEP setting for COPD? | 0 (ZEEP).
Permissive hypercapnia limit? | pH ≥ 7.1 acceptable.
Vent approach for asthma? | Same as COPD: low rate, long expiration, ZEEP, permissive hypercapnia.
Key vent strategy in DKA? | Match or exceed pre-intubation RR to maintain minute ventilation and prevent acidosis.
Why track EtCO₂ before intubation in DKA? | Use baseline value to guide post-intubation ventilation.
Common causes of ARDS? | Sepsis, aspiration, pneumonia, trauma, transfusion, overdose.
Berlin diagnostic criteria for ARDS? | Onset ≤ 1 wk, bilateral infiltrates, not cardiac, PaO₂/FiO₂ < 300.
Findings suggesting cardiogenic cause? | S3/S4, JVD, Kerley B lines, cardiomegaly, ↑ BNP, abnormal echo.
Ventilation strategy for ARDS? | Low Vt (6 mL/kg), PEEP 5, FiO₂ 100% → titrate, open-lung approach.
Purpose of recruitment maneuver? | Sustained inspiration (~30 s) to reopen alveoli.
Supportive care in ARDS? | Sedation, paralysis, DVT/GI prophylaxis, nutrition, glucose and fluid control.
Effect of prone ventilation? | Improves oxygenation; no mortality benefit; ↑ risk of aspiration and pressure sores.
Inclusion criteria for ARDS protocol? | PaO₂/FiO₂ < 300, bilateral infiltrates, no LA HTN.
Starting tidal volume for ARDS? | 8 mL/kg → reduce to 6 mL/kg.
Target pH range for ARDS? | 7.30–7.45.
If pH < 7.15 in ARDS? | ↑ Vt by 1 mL/kg or give NaHCO₃.
If pH > 7.45 in ARDS? | Decrease RR.
I:E ratio goal in ARDS? | Inspiration ≤ expiration duration.
PBW formula (male)? | 50 + 2.3 × (height in – 60).
PBW formula (female)? | 45.5 + 2.3 × (height in – 60).