AS11.1-6 | Oxygen Therapy and Airway Management Foundations — Practice Quiz

The Venturi mask is a fixed-performance device that delivers a precise, predetermined FiO₂ regardless of the patient's breathing pattern. The 28% adaptor is appropriate for titrated oxygen therapy in COPD, avoiding uncontrolled hyperoxia.

The Venturi mask is the fixed-performance device of choice when a precise FiO₂ is required — especially in COPD patients who may rely on hypoxic drive. The delivered FiO₂ is fixed by the jet size; increasing the oxygen flow beyond the specified rate does not improve FiO₂ precision.

The Venturi mask is the only device listed that guarantees a fixed FiO₂ in COPD. Nasal cannula and simple mask are variable-performance devices whose FiO₂ changes with respiratory rate and tidal volume. The non-rebreather mask delivers very high FiO₂ (60–90%) and is inappropriate here.

The simple face mask has exhalation ports but no one-way valves, so exhaled CO₂ accumulates in the mask reservoir. A minimum flow of 5 L/min is required to flush this dead-space gas and prevent rebreathing of CO₂.

The simple face mask must never be run at less than 5 L/min; below this threshold, exhaled CO₂ accumulates in the mask body (volume ~100–200 mL) and is re-inhaled on the next breath. Adequate flow both delivers oxygen and flushes the dead space.

The reservoir bag belongs to the non-rebreather mask, not the simple mask. Adding valves to the simple mask would convert it to a different device. At 5 L/min via nasal cannula, FiO₂ is only ~40% — lower than a simple mask at adequate flow. The correct answer is maintaining a minimum 5 L/min flow through the simple mask.

In suspected cervical spine injury, the jaw thrust (without head tilt) is the recommended primary airway manoeuvre because it opens the airway by displacing the mandible anteriorly without extending the neck, thereby minimising cervical cord movement.

The jaw thrust is the correct basic airway manoeuvre when cervical spine injury is possible. It opens the airway without cervical extension. If the jaw thrust alone is insufficient to maintain the airway, a cautious head tilt may be added — airway patency takes priority over spinal precautions.

The head-tilt chin-lift is contraindicated in suspected cervical spine injury as it extends the neck. Oropharyngeal airway insertion is an adjunct, not an opening manoeuvre, and requires a patent airway to be effective. Immediate intubation comes after basic manoeuvre failure. Neck extension is exactly what should be avoided.

In adults, the OPA is inserted with the concave side facing the palate (upward) to avoid pushing the tongue posteriorly. Once the tip reaches the soft palate, it is rotated 180° so the concave side faces downward, following the tongue curvature into the oropharynx.

Adult OPA insertion uses a 180° rotation technique: insert concave-side-up to glide along the palate, then rotate as the tip passes the soft palate so the curved flange follows the tongue. This prevents the tongue from being pushed posteriorly.

Inserting the OPA concave-side-down from the start can push the tongue backward and worsen obstruction. In children, a tongue depressor is used instead of the rotation technique (to avoid palatal injury), but in adults the rotation method is standard. A 90° lateral insertion is not the standard technique.

Retching and coughing indicate an intact gag reflex. The OPA is contraindicated in patients with an intact gag reflex due to risk of vomiting and aspiration. The NPA is better tolerated in semi-conscious patients because it does not contact the oropharynx.

The gag reflex is the OPA/NPA decision gate. An intact gag reflex (retching, coughing on OPA insertion) means the OPA is contraindicated. Switch to a nasopharyngeal airway, which is better tolerated in semi-conscious patients as it lies outside the oropharynx.

Holding an OPA in place in a gagging patient risks vomiting and aspiration. Sedation to suppress gag reflexes is a major intervention with its own risks and is not appropriate as a first-line response to a wrongly placed airway adjunct. Downsizing the OPA does not remove the stimulus to the oropharynx — the gag reflex is the decision gate, not the size.

This patient meets the criteria for advanced airway management: inability to oxygenate (SpO₂ <90% despite BVM + 100% O₂), inability to protect the airway (GCS ≤8), and failure of basic manoeuvres. Endotracheal intubation is the definitive airway.

Advanced airway management is indicated when basic manoeuvres fail and any of: inability to oxygenate (SpO₂ <90% despite NRM/BVM), inability to ventilate (progressive hypercapnia), or failure of airway protection (GCS ≤8). Endotracheal intubation provides the most secure definitive airway.

Basic adjuncts have already failed; continuing with BVM or adjuncts alone will not resolve the problem. A non-rebreather mask requires a spontaneously breathing patient. Recovery position is for the unconscious patient with a patent airway — it does not solve active respiratory failure. IV fluids do not address airway or oxygenation failure.

Tidal volume for mechanical ventilation should be based on ideal body weight (IBW), not actual body weight. Lung-protective ventilation uses 6–8 mL/kg IBW. For a patient with IBW of 70 kg, 560 mL represents 8 mL/kg IBW — an appropriate lung-protective starting tidal volume.

Tidal volume for mechanical ventilation must be calculated using ideal body weight (IBW), not actual body weight. Lung-protective VT is 6–8 mL/kg IBW. An obese patient's lungs are not bigger — using actual weight risks volutrauma and ventilator-induced lung injury.

Using actual body weight in an obese patient would result in VT far exceeding lung capacity, causing ventilator-induced lung injury (VALI). 10 mL/kg is the older, now-abandoned target. While minute ventilation is relevant to CO₂ clearance, tidal volume is specifically set per IBW to avoid volutrauma.

The ABG shows respiratory acidosis (low pH, elevated PaCO₂) with normal HCO₃⁻ (no metabolic compensation yet), indicating acute hypoventilation. PaO₂ is adequate (88 mmHg on FiO₂ 0.4). The priority is to increase alveolar ventilation — most safely achieved by increasing respiratory rate.

When the ABG shows respiratory acidosis (high PaCO₂, low pH, normal HCO₃⁻), the ventilator adjustment needed is an increase in alveolar ventilation — either by increasing respiratory rate or tidal volume. Increasing RR is often preferred as it avoids increasing VT above safe lung-protective limits.

PaO₂ is acceptable; increasing FiO₂ does not address the high PaCO₂. PEEP primarily addresses oxygenation and alveolar recruitment, not CO₂ clearance. Decreasing tidal volume will worsen hypoventilation and further raise PaCO₂. The problem is insufficient minute ventilation causing CO₂ retention.