This study evaluated the effects of prehospital continuous positive airway pressure (CPAP) on physiologic measures in 109 patients with acute dyspnea. CPAP improved respiratory rates in 46.4% of patients with an initial rate over 25 breaths per minute. Oxygen saturation improved to over 95% in 34.2% of patients with an initial saturation under 90%. End-tidal carbon dioxide levels improved to under 40 mmHg in 38.9% of patients with initial levels over 40 mmHg. Intubation was required for 11% of patients. The study found that prehospital CPAP resulted in similar levels of improvement in oxygenation and ventilation parameters as seen in previous studies.

1. Effect of Prehospital Continous Positive Airway Pressure (CPAP)
On Physiologic Measures Including Capnography
David E. Slattery, MD 1,2,5; Ryan Hodnick, DO 1,2; Bryan Bledsoe, DO 1,2,3; Eric Anderson, MD 4; Larry Johnson, NREMT-P 1,3,4 ;
Eric Dievendorf, NREMT-P 1,4; Stephen Johnson, NREMT-P 1,3
1 University of Nevada School of Medicine; 2 University Medical Center of Southern Nevada, 3 MedicWest Ambulance; 4American Medical Response, Las Vegas, Nevada;
5Las Vegas Fire and Rescue
BACKGROUND
Continuous positive airway pressure (CPAP) devices
for noninvasive ventilation (NIV) have become
increasingly more common in the prehospital
setting.1-2 It has been demonstrated to be effective
in the management of acute pulmonary edema as
well as other respiratory conditions.3-5 CPAP has
been shown to be cost-effective and reduces the
need for intubation.6-8
OBJECTIVE
To determine the effects of prehospital CPAP on
objective physiologic measures, including
capnography (ETCO2), in shortness of breath
patients.
METHODS
Prospective, observational, non-blinded study of
patients age >18 evaluated by EMS for acute
dyspnea. Inclusion Criteria: Patients meeting 2
or more of the following criteria were enrolled:
retractions or accessory muscle use, respiratory
rate (RR) greater than 25 breaths/minute, or
SpO2 less than or equal to 94% (see Figure 1).
Patients were excluded for: inability to follow
commands, apnea, vomiting/GI bleed, and major
trauma. Paramedics applied the CPAP (Pulmodyne
O2-ResQ™) (see Figure 2) and used a standardized
data collection tool to record initial and repeat
physiologic parameters at 5-minute intervals.
The following data were captured: blood pressure ,
heart rate, RR, SpO2, and ETCO2. The primary
outcome measure was the proportion of patients
with an initial RR >25 who improved (defined as a
decrease in the final RR by >5) after CPAP.
Secondary outcome measures: Proportion with
improved SPO2-defined as those with initial
SPO2 <90% improved to >95%; proportion with
improved ETCO2 (>40 to <40); the proportion who
required intubation by EMS or immediately
upon ED arrival; and subjective assessment of
efficacy by treating EMS personnel.
RESULTS
•109 patients were enrolled.
•42 % (46/109) were female.
•Average age = 67.1 (range 21-96 years)
Conditions treated based on paramedic
impression included:
•Asthma 22%,
•COPD 42%,
•CHF 49%, and
•Pneumonia 23%.
Primary outcome measure:
•Of those with an initial RR >25, 45/97
(46.4% 95%CI=37-56) improved.
Secondary measures:
•Of those with an initial SPO2 <90,
improvement was achieved in 26/76 (34.2%
95%CI=25-45); for those with ETCO2>40,
7/18 (38.9 % 95%CI=20-61) improved;
12/109 (11% 95%CI= 6-18 )
required EMS intubation. (see Figure 3)
Limitations
Small study size, incomplete ETCO2 data,
hospital intubation rates and length of stay
not measured, non blinded, no comparison
group.
CONCLUSIONS
In our cohort, prehospital CPAP application
for acute dyspnea resulted in a similar level
of improvement in oxygenation and
ventilation parameters.
REFERENCES
1. National Association of EMS Physicians. Noninvasive positive pressure
ventilation. Prehosp Emerg Care. 201115:418.9
2. Daily JC, Wang HE. Noninvasive positive pressure ventilation: resource
document for the National Association of EMS Physicians position statement.
Prehosp Emerg Care. 2011;15:532-538.
3. Hubble MW, Richards ME, Jarvis R, Millikan T, Young D. Effectiveness of
continuous positive airway pressure in the management of acute pulmonary
edema. Prehosp Emerg Care. 2006;10:430‐439.
4. Kallio T, Kuisma M, Alaspää A, Rosenberg PH. The use of prehospital
continuous positive airway pressure treatment in presumed acute severe
pulmonary edema. Prehosp Emerg Care. 2003;7:209‐213.
5. Gray A, Goodacre S, Newby DE, et al. Noninvasive ventilation in acute
cardiogenic pulmonary edema. N Engl J Med. 2008;359:142‐151.
6. Hubble MW, Richards ME, Wilfong DA. Estimates of cost--effectiveness of
prehospital continuous positive airway pressure in the management of acute
pulmonary edema. Prehosp Emerg Care. 2008;12:277‐285.
7. Simpson PM, Bendall JC. Prehospital non-invasive ventilation for acute
cardiogenic pulmonary oedema: an evidence-based review. Emerg Med J.
2011;28:609‐612.
8. Wang HE, Balasubramani GK, Cook LJ, Yealey DM, Lave JR. Medical
conditions associated with out‐of‐hospital intubation. Prehosp Emerg Care.
2011;15:338-346..
Figure 3. Initial RR >25, 45/97 (46.4% 95%CI=37-56) improved >5,
initial SPO2 <90, improvement (>95%) achieved in 26/76 (34.2%
95%CI=25-45); for those with ETCO2 >40,7/18 (38.9 % 95%CI=20-61)
improved to ETCO2 < 40; 12/109 (11% 95%CI= 6-18 ) required EMS
intubation.
Figure 1. Protocol used by both Agencies
Percentage
Figure 2: Pulmodyne O2-ResQ™
CPAP Device
NAEMSP Disclosure Statement: Authors have no conflicts of interest to disclose.
Funding: .
• No input or interpretation of data results
• No investigators received financial compensation