Skip to main content

Table 1 Exhaled air dispersion distances during various treatments and conditions, with usual set-up

From: Knowledge translation tools to guide care of non-intubated patients with acute respiratory illness during the COVID-19 Pandemic

Condition

Distance (mm)

Mechanism of dispersion

Coughing [18]

  

 No mask

680

Forward jet

 Wearing surgical mask

300

Sideway leakage

 Wearing N95 mask

151

Sideway leakage

Simple oxygen mask [19]

  

 2 LPM

200

Lateral leakage from side vents

 4 LPM

220

 

 8 LPM

300

 

 10 LPM

400

 

HFNO [21] (normal lung condition*)

  

 10 L/min

65

 

 30 L/min

130

 

 60 L/min

172

 

 Displaced interface tube: 60 L/min

620

 

NIV—CPAP [21]

  

 Swift FX nasal pillows: CPAP 5 cm H2O

207

 

 Swift FX nasal pillows: CPAP 20 cm H2O

332

 

 ResMed Quattro Air oronasal mask: CPAP 5 cm H2O

Negligible

 

 ResMed Quattro Air oronasal mask: CPAP 20 cm H2O

Negligible

Circular vent holes; no distinct jet

NIV—Bi-PAP/ total facemask [20]

  

 Respironics Full Face IPAP/EPAP: 10/5 cm H2O

618

Simulated for mild lung injury

 Respironics Full Face IPAP/EPAP: 18/5 cm H2O

812

Simulated for mild lung injury

NIV—Bi-PAP/oronasal mask [22]

  

 Respironics Comfort 2 mask IPAP/EPAP: 10/4 cm H2O

650

 

 Respironics Comfort 2 mask IPAP/EPAP: 18/4 cm H2O

850

 

 Respironics Image 3 mask + Whisper Swivel

  

  IPAP/EPAP: 10/4 cm H2O

950

 

  IPAP/EPAP: 18/4 cm H2O

 > 950

Diffuse dispersion

NIV—Bi-PAP/ helmet [20]

  

 Sea-Long helmet IPAP/EPAP: 12/10 cm H2O

150

Dispersion through neck interface

 Sea-Long helmet IPAP/EPAP: 20/12 cm H2O

230

 

StarMed CaStar R helmet

Negligible

Better neck seal using air cushion

  1. All studies by David Hui
  2. Airflow was marked with intrapulmonary smoke for visualization using a human patient stimulator (HPS) to mimic different devices and severity of lung injury
  3. *Less exhaled distances with more severe lung injury at all flows during HFNO