The purpose of this study is to describe the safety and efficacy of nitrous oxide
administration for pain and anxiety before propofol in patients requiring any procedure
under sedation in the Emergency Department. Procedural sedation is the use of sedative,
analgesic, and/or dissociative agents to relieve anxiety and pain associated with diagnostic
and therapeutic procedures. Propofol is commonly used and is a sedative and amnestic, but
provides no analgesia. Short acting opioids may be used for pain relief, but come with the
risk of respiratory depression. An optimum analgesic to relieve pain in patients who need
procedural sedation should be short acting, easy to administer and safe. Nitrous oxide may
be a suitable agent, but literature supporting or rejecting its use in adults is lacking.
This study aims to fill this gap. Adult patients capable of consenting, coming to the
Emergency Department with painful condition requiring procedural sedation are the targeted
population. Eligible patients who consent to the study will receive Nitrous Oxide gas
delivered through a hand held mask before they receive propofol for the procedure.
Information regarding their vitals, pain scores and medical condition will also be
This pilot study will be conducted in a prospective, non-randomized fashion using a
convenience sample of 100 subjects undergoing sedation for Emergency Department procedures.
Recruitment Methods The research associates as well as the health care team (both residents
and attending physicians) will screen patients who may need procedural sedation in the
Emergency Department and may qualify for the study. Research associates will use the Medical
Procedures Involved in the Research Initial medical assessment will be made in accordance
with established clinical procedures, including the history, physical examination, and vital
signs. If by clinical assessment the patient meets eligibility criteria, then they will be
approached by a research associate for enrollment in the study. After informed consent is
obtained and prior to starting the sedation, standard vital sign monitoring will be placed
on the patient (electrocardiogram, non-invasive blood pressure monitoring, pulse oximetry,
and capnography). Level of consciousness will be determined using the modified Ramsay scale,
which will be assessed at baseline. The Entitled Carbon Di Oxide (CO2) monitor will be used
as the primary device to measure Entitled Carbon Di Oxide (CO2), with a nasal cannula
capable of delivering supplemental oxygen and measuring Entitled CO2.
The Nitrous Oxide gas mixer system will be used as the primary nitrous oxide delivery
device. It will mix and deliver nitrous oxide and oxygen in a 1:1 ratio, at a fixed
concentration of 50%/50%. It uses a patient driven demand valve system that is hand held.
This device provides a consistent, fixed 50%/50% blend of nitrous oxide (N2O) and oxygen
(O2), eliminates the need to titrate, and provides fixed concentrations for controlled and
consistent dosing. The device comparator detects dosing imbalance to protect against hypoxic
mixtures, it cannot deliver nitrous gas without concurrent oxygen, and the device has an
anti-asphyxia valve override. The on demand valve requires patient inspiration to trigger
dosing. This portable device scavenges exhaled waste gases for environmental safety, as well
as a key mechanism that renders the system inoperable without it for security.
After informed consent, the patient will fill out a pre procedure questionnaire and a 100 mm
VAS baseline pain scale. The patient will be given the mask for delivery of nitrous oxide,
and instructed on its use. The research associate will mark the time the patient began using
the device electronically. Once IV access is established, and the team and patient are ready
to begin the procedure, the nitrous oxide mask will be removed, and a 100% non rebreather
mask delivering 15 liters a minute of supplemental oxygen will be placed on the patients
face. The loading dose of propofol will then be administered immediately. All sedations in
this trial will use propofol 1.0 mg/Kg initial dose, with 0.5 mg/Kg doses titrated to deep
sedation. Once the patient is deeply sedated, the procedure will begin.
The subject's clinical data and sedation information (refer to data management) will be
entered into a standardized data collection form. The data will be continuously recorded
throughout the sedation and recovery periods. Study will end when the subjects recovers back
to baseline mental status.
Vital signs will be flagged electronically when a physician intervenes for clinical
respiratory depression. Respiratory depression will be defined as peripheral Oxygen
saturation below 92%, Entitled CO2 level above 50, a rise or decrease of 10% above or below
baseline, the loss of the Entitled CO2 waveform for more than 15 seconds. Level of
consciousness will be determined using the modified Ramsay scale, which will be recorded at
baseline and at the point of deepest sedation. Once the procedure is complete, and the
patient is deemed back to their mental status baseline, they will fill out a post procedure
satisfaction questionnaire, and a 100 mm VAS scale. They will be asked about procedure
recall. The physician and nurse involved will also fill out a post procedure questionnaire.
System for screening, and they will be in charge of informed consent, enrollment, placement
of the capnography monitor, as well as data collection. The health care team will be in
charge of the procedural sedation and all other management.
- Spontaneous respirations
- 18 years of age and older
- American Society of Anesthesiologists (ASA) Physical Status Classification 1 or 2,
who will be receiving sedation for an Emergency Department procedure.
- Ability to provide informed consent.
- Comorbidities that affect ventilation, perfusion, or metabolism
- Cardiopulmonary instability
- Major trauma
- American Society of Anesthesiologists (ASA) class 3, 4, and 5.
- Inability to provide informed consent
- Nursing home residents
- Age less than 18 years
- Non English speaking
- Pregnant women
- Under police custody