Final Considerations to Ventilator Setup – Specific Patient Populations

32 question-and-answer flashcards covering ventilator setup and management for COPD, asthma, neuromuscular disorders, closed head injury, ARDS, and congestive heart failure, along with related physiologic concepts such as auto-PEEP, permissive hypercapnia, CPP, and PEEP/FiO₂ titration.

Why is non-invasive ventilation (e.g., BiPAP) preferred initially for COPD exacerbations requiring ventilatory support?

It avoids complications of artificial airways while providing adequate pressure support for chronic pulmonary disorders.

In volume-controlled CMV for COPD, what peak inspiratory flow and flow pattern should be set to meet patient demand?

60 L/min with a descending (decelerating) flow pattern.

What PEEP range is recommended at initiation of mechanical ventilation for most COPD patients?

5–8 cm H₂O.

For COPD or asthma, what initial tidal-volume and respiratory-rate ranges help minimize air trapping?

VT 4–8 mL/kg and RR 8–16 breaths/min.

Which plateau pressure (Pplat) limit should be respected in COPD to avoid alveolar over-distention?

What PaO₂ and FIO₂ goals are appropriate for ventilated COPD patients?

Maintain PaO₂ 55–75 mm Hg (or patient’s baseline) with FIO₂ <0.5 if possible.

How can clinicians minimize dynamic hyperinflation (auto-PEEP) in COPD?

Provide the lowest VE that gives acceptable gas exchange, allow long expiratory times, and monitor for intrinsic PEEP.

Why may PC-CMV have an advantage over PSV during the acute phase of COPD ventilation?

PC-CMV guarantees flow on demand and a set inspiratory pressure, whereas PSV may give breaths that are too long or short as patient effort varies.

What adjunctive care is essential for COPD patients on the ventilator besides settings?

Adequate hydration, bronchodilators, corticosteroids, secretion clearance, and appropriate antibiotics for infection.

Which ventilator modes are acceptable immediately after intubation of a patient in acute severe asthma?

VC-CMV or PC-CMV (pressure control makes airway pressure easier to limit).

In ventilating asthma, what plateau pressure limit is critical despite potentially high peak pressures?

Keep Pplat <30 cm H₂O.

What range of permissive hypercapnia is generally accepted in severe asthma if pH ≥7.20?

PaCO₂ 45–80 mm Hg.

List four ventilator adjustments that reduce air trapping in ventilated asthma.

Low RR (<8 breaths/min), VT 6–8 mL/kg, TI ≤1 s, high inspiratory flow 80–100 L/min with descending waveform.

What complications of severe air trapping should be monitored for in ventilated asthma patients?

Barotrauma such as pneumothorax, pneumomediastinum, and subcutaneous emphysema.

Why do neuromuscular-disorder patients often require mechanical ventilation?

Respiratory-muscle weakness leads to ineffective cough, secretion retention, atelectasis, pneumonia, and eventual ventilatory failure.

Give typical initial ventilator settings for a neuromuscular-disorder patient (VT, RR, flow, PEEP).

VT 6–8 mL/kg, RR 8–16/min, inspiratory flow ≥60 L/min (TI ≈1 s), PEEP ≈5 cm H₂O.

What trigger sensitivity issue commonly arises in ventilated neuromuscular patients?

Trigger threshold set too high causes missed efforts; flow or pressure trigger must be adjusted for weak patient effort.

State the formula for cerebral perfusion pressure (CPP).

CPP = Mean arterial pressure (MAP) − Intracranial pressure (ICP).

What PaCO₂ range may be temporarily targeted to lower ICP after an acute closed head injury?

25–30 mm Hg (controlled hyperventilation).

Why is PEEP generally limited (≤5 cm H₂O) in patients with closed head injuries?

High intrathoracic pressure can impede cerebral venous return and raise ICP.

Initial ventilator settings for closed-head-injury patients include what VT, RR, and FiO₂ values?

VT 6–8 mL/kg, RR 15–20/min (to maintain normal pH), FiO₂ 1.0 then titrate to PaO₂ 70–100 mm Hg.

List three characteristic pathophysiological findings of ARDS.

Severe hypoxemia, increased pulmonary vascular permeability with bilateral opacities, and decreased lung compliance.

What low-tidal-volume strategy is recommended for ARDS to keep Pplat <30 cm H₂O?

VT 4–6 mL/kg (can use 6–8 mL/kg if Pplat remains below 30 cm H₂O).

What SaO₂ goal and adjunctive measure (with rationale) are used in ARDS to improve oxygenation while limiting FIO₂?

Maintain SaO₂ ≥88–90% using PEEP high enough to prevent alveolar collapse and permit lower FIO₂.

When ARDS oxygenation remains inadequate, which supportive steps may improve outcomes?

Sedation, paralysis, prone positioning, optimization of cardiac output and hemoglobin.

What inspiratory flow or TI guideline helps balance oxygenation and avoid auto-PEEP in ARDS?

Flow >60 L/min in VC or TI 0.8–1.2 s in PC ventilation.

How are PEEP and FIO₂ often titrated together in ARDS management?

Use higher PEEP with lower FIO₂ or lower PEEP with higher FIO₂ according to PEEP-FIO₂ tables to maintain adequate oxygenation while minimizing oxygen toxicity.

Why can positive pressure ventilation (especially PEEP) benefit patients with acute cardiogenic pulmonary edema/CHF?

It reduces venous return and left-ventricular preload, decreasing myocardial work and improving oxygenation.

What non-invasive mode is frequently adequate for acute CHF with pulmonary edema?

Mask CPAP (or bilevel NIV) to decrease WOB and improve oxygenation.

Provide initial invasive-ventilation settings for CHF (VT, RR, PEEP, FiO₂).

VT 6–8 mL/kg, RR ≥10/min, PEEP 5–10 cm H₂O, FiO₂ 1.0 then titrate to SpO₂ 90–92%.

What clinical parameters should be closely monitored in ventilated CHF patients besides ABGs and SpO₂?

Urine output, electrolytes, and systemic hemodynamics to assess cardiac and renal function.

What waveform finding indicates trigger asynchrony caused by auto-PEEP?

Negative pressure or flow deflections that fail to trigger a breath while expiratory flow is still present.