emDOCs Podcast: Episode 48 – Ventilator Management

Today on the emDOCs cast with Brit Long, MD (@long_brit) and Skyler Lentz, MD (@SkylerLentz), we cover managing the ventilator in the ED setting.

Episode 48: Ventilator Management

Background:

• Managing the ventilator and ensuring appropriate settings are vital; these have a significant impact on patient outcomes.
• LOV-ED Trial: Quasi-experimental, before-after study, evaluating a multifaceted ED-based mechanical ventilator protocol. This targeted lung-protective tidal volume, appropriate setting of positive end-expiratory pressure, rapid oxygen weaning, and head-of-bed elevation.
  • Authors found increased ventilator-free days, ICU-free days, and hospital-free days with protocol.
  • The mortality rate was 34.1% in the preintervention group and 19.6% in the intervention group with the protocol (adjusted OR 0.47; 95% CI 0.35 to 0.63).
  • Fuller BM, Ferguson IT, Mohr NM, Drewry AM, Palmer C, Wessman BT, Ablordeppey E, Keeperman J, Stephens RJ, Briscoe CC, Kolomiets AA, Hotchkiss RS, Kollef MH. Lung-Protective Ventilation Initiated in the Emergency Department (LOV-ED): A Quasi-Experimental, Before-After Trial. Ann Emerg Med. 2017 Sep;70(3):406-418.e4

Goals:

• Utilize appropriate tidal volume
• Limit and measure plateau pressure
• Set appropriate PEEP
• Avoid hyperoxia, ventilate appropriately
• Head of bed up, OG to decompress stomach and decrease aspiration
• Appropriate analgesia and sedation

Settings:

• Tidal Volume
  • Tidal volume 6-8 ml/kg IDEAL body weight
  • Modes: Volume vs. pressure (most In ED use volume, which gives a guaranteed volume).
  • Assist control vs. SIMV – pick a setting that allows set volume and respiratory rate (RR).
• Respiratory Rate
  • 10 to 30 breaths per minute (depends on underlying etiology)
  • Lower RR for obstructive lung disease (permissive hypercapnia) and higher RR for metabolic acidosis (compensation to blow off CO2).
  • Effects minute ventilation and expiratory time.
  • Watch for air trapping in obstructive lung disease.
• PEEP
  • 5 cm H20 for most
  • Obese or severely hypoxemic from ARDS (bilateral infiltrates) need more start at 8-10 cm H2O
• FiO2
  • Avoid hyperoxia – reduce FiO2 as soon as feasible and safe.
• Pressures
  • Peak pressure goal < 30-35 cm H20
    • This is the sum of all pressures in volume targeted modes, includes airway resistance.
  • Plateau pressure goal < 30 cm H2O
    • This is the pressures in the small airways and alveoli; what we are primarily concerned with.
    • Measure with end-inspiratory hold
  • Alarms:
    • High peak and normal plateau – resistance problem
    • High peak and high plateau – compliance problem

Putting it all together:

• Acute lung injury/ARDS-bilateral infiltrates
  • Problem: Injured alveoli cannot accept volume and exchange oxygen as well as healthy alveoli
  • Higher PEEP, plateau < 30 cm H20, Vt 4-6 ml/kg
• Obstructive lung disease
  • Problem: Obstruction and limitations in exhalation.
  • Lower RR, monitor for air trapping, permissive hypercapnea/pH 7.2 is ok