Mechanical and Advanced Ventilatory Support - NREMT Paramedic Level

1. What is the correct formula for minute ventilation ($\dot V_E$) used when setting a ventilator?

   $\dot V_E=V_T\times RR$. This calculates total gas volume moved per minute to guide ventilation settings.

2. What is the correct formula for mean arterial pressure (MAP) used when reassessing ventilated patients?

   $MAP=DBP+\frac{1}{3}(SBP-DBP)$. This formula estimates average arterial pressure to monitor perfusion in ventilated patients.

3. What is pressure support ventilation (PSV) intended to do for spontaneous breaths?

   Augment spontaneous breaths with preset inspiratory pressure. This reduces inspiratory work by providing pressure assistance during patient-triggered breaths.

4. What is the primary contraindication to noninvasive ventilation (CPAP/BiPAP) in the field?

   Inability to protect airway (e.g., vomiting, altered mental status). This increases aspiration risk, necessitating invasive ventilation for airway protection.

5. Which parameter primarily determines ventilation (CO2 removal): FiO2, minute ventilation, or PEEP?

   Minute ventilation primarily determines CO2 removal. This controls CO2 elimination by determining alveolar ventilation rate.

6. Which capnography finding most strongly suggests esophageal intubation?

   Absent or rapidly diminishing ETCO2 waveform despite ventilation. This indicates lack of CO2 from the trachea, confirming improper tube placement in the esophagus.

7. Which parameter primarily determines oxygenation: FiO2, tidal volume, or respiratory rate?

   FiO2 (and PEEP) primarily determine oxygenation. These settings enhance oxygen delivery and alveolar recruitment to improve arterial oxygenation.

8. Which ventilator mode delivers a set tidal volume (or minute ventilation) with mandatory breaths?

   Volume-controlled ventilation (VC/AC or CMV). This mode ensures consistent tidal volume delivery regardless of changing lung compliance.

9. What is the correct formula for static compliance ($C_{stat}$) when plateau pressure is available?

   $C_{stat}=\frac{V_T}{P_{plat}-PEEP}$. This assesses lung distensibility by relating volume to pressure difference at zero flow.

10. What is the key functional difference between CPAP and BiPAP (NIV) settings?

    BiPAP provides two pressures (IPAP and EPAP); CPAP provides one. BiPAP assists inspiration and expiration separately, improving ventilation over constant CPAP.

11. Which condition is suggested by rising ETCO2 with increasing airway pressures and worsening hypoxia?

    Hypoventilation or increased dead space; consider obstruction/bronchospasm. This reflects CO2 retention from impaired gas exchange or increased airway resistance.

12. Identify the typical initial adult tidal volume target used for lung-protective ventilation.

    $6$-$8$ mL/kg ideal body weight. This range minimizes volutrauma while ensuring adequate ventilation in protective strategies.

13. Which ventilator adjustment most directly increases expiratory time to reduce auto-PEEP?

    Decrease respiratory rate (and/or decrease tidal volume). This prolongs exhalation phase to allow complete lung emptying and prevent air trapping.

14. What is auto-PEEP (dynamic hyperinflation) most commonly caused by on a ventilator?

    Insufficient expiratory time, often from high RR or large tidal volume. This leads to air trapping and hyperinflation due to incomplete exhalation.

15. Which ventilator alarm condition is most consistent with circuit disconnection or a cuff leak?

    Low pressure or low exhaled tidal volume (low-pressure alarm). This alarm indicates a system leak preventing adequate pressure or volume delivery.

16. What is PEEP (positive end-expiratory pressure) defined as on a mechanical ventilator?

    Positive pressure maintained at end-expiration to prevent alveolar collapse. This improves oxygenation by increasing functional residual capacity and alveolar recruitment.

17. What is SIMV (synchronized intermittent mandatory ventilation) designed to allow between mandatory breaths?

    Spontaneous breaths between synchronized mandatory breaths. This promotes patient-ventilator synchrony and facilitates weaning from mechanical support.

18. Which ventilator mode delivers a set inspiratory pressure and allows tidal volume to vary?

    Pressure-controlled ventilation (PC/AC). This mode limits barotrauma by controlling pressure while adapting to lung mechanics.

19. What is CPAP (continuous positive airway pressure) defined as for a spontaneously breathing patient?

    Continuous positive pressure throughout the entire respiratory cycle. This maintains airway patency and enhances oxygenation in patients with spontaneous respirations.

20. What is the primary clinical goal of mechanical ventilation in the prehospital setting?

    Maintain oxygenation and ventilation while reducing work of breathing. This ensures adequate gas exchange and minimizes patient effort in acute respiratory failure.

21. What is the most reliable immediate method to confirm correct endotracheal tube placement after intubation?

    Continuous waveform capnography (ETCO2). This provides real-time CO2 detection to confirm tracheal placement and monitor ventilation.

22. What immediate action should you take if a ventilated patient suddenly deteriorates and the cause is unclear?

    Disconnect and ventilate with a BVM and $100\%$ oxygen. This allows manual oxygenation and rapid assessment using the DOPE mnemonic for troubleshooting.

23. What is the correct immediate management for suspected ventilator-associated tension pneumothorax?

    Needle decompression (or finger thoracostomy per protocol) and reassess. This relieves intrathoracic pressure to restore venous return and lung expansion.

24. Identify the most likely cause when ETCO2 suddenly drops to near zero with an abrupt loss of waveform.

    Ventilator/circuit disconnection or extubation (loss of exhaled CO2). This suggests sudden interruption of gas flow from the patient's airway to the capnograph.

25. Which ventilator alarm condition is most consistent with a kinked tube or mucus plugging?

    High peak inspiratory pressure (high-pressure alarm). This alarm triggers from increased airway resistance obstructing flow.

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