Replacing Several single function Oxygen delivery masks with a

2013
BLS Systems Limited
Edward J. Reesor, RRT, MBA
Director of Marketing
REPLACING SEVERAL SINGLE
FUNCTION OXYGEN DELIVERY
MASKS WITH A SINGLE MULTIFUNCTION DEVICE
This document will discuss the current healthcare culture of applying several single function oxygen
delivery masks, their function and the ability to deliver superior therapy using a single multifunction
device.
Executive Summary
The regular use of single function non-rebreather masks, simple masks and small volume nebulizer
masks significantly lower the efficiency of healthcare delivery while unnecessarily inflating costs.
Qualitative research suggests that common oxygen masks deliver significantly lower oxygen
concentrations than assumed, providing an obstacle for quality healthcare and potentially place patients
at increased risk of harm. The FLO2MAX and O-Mask High Concentration Oxygen Masks by BLS Systems
Limited combine four single function oxygen delivery devices into one device, thus improving patient
care while maintaining organizational efficiency.
The FLO2MAX and O-Mask series of masks provide superior function than any single function mask
while reducing the number of devices staff are responsible for. The FLO2MAX and O-Mask High
Concentration oxygen masks simplify healthcare delivery, optimize therapeutics, reduce occupational
exposure to airborne contaminants and reduce costs associated with maintaining several SKU’s.
Key differences are captured in the following chart:
Small
NonMedium
volume
rebreather concentration
nebulizer
mask
(Simple) Mask
mask
Oxygen
concentration
55-60% (Garcia,
Earl)
FLO2MAX
O-Mask
43-69%
35-50%
24-99%
24-99%
Automatic
with
integrated
filter
Ability to
connect
standard filter
Ability to
filter exhaled
particles
None. Have
been associated
with spreading
organisms
None. Have been
associated with
spreading
organisms
None. Have
been strongly
associated
with
spreading
organisms
Number of
functions
1
1
1
5
4
Common sizes
Adult, Child
Adult, Child
Adult, Child
Large Adult,
Small Adult,
Child
Large Adult,
Small Adult,
Child
Sole function
Yes
(now
available with
MDI port)
Yes
Ability to
Deliver
Medications
None
None
2
Introduction
Hospitals rely on many types of oxygen delivery devices to treat patients effectively and to the best of
the abilities of the healthcare provider. Unfortunately there is an industry wide dependency on
inefficient, single function devices to perform the necessary therapeutics, leading to the application of
several single function devices on a patient through their care plan. The supply management, staff
instruction, inventory control and waste management costs associated with several similar but separate
single function products unnecessarily increase the cost of healthcare delivery.
The most common types of masks used to deliver oxygen and medication are the non-rebreather mask,
the medium concentration (simple) mask and the aerosol/small volume nebulizer (SVN) mask. These
masks are normally available in two sizes; adult and child, and are used by all healthcare providing
facilities in considerably large numbers. The average patient may use two or more of these single
function masks during their admission. Investigation into the 2003 SARS outbreak identified these
masks as contributing to the spread of respiratory borne particles.
The FLO2MAX and O-Mask High Concentration Oxygen Therapy Masks were designed and developed to
combine the above mentioned mask types into one unit while offering superior performance. This
document will describe each mask type and the issues that are experienced during normal application.
3
Conventional Non-rebreather Mask
The conventional non-rebreather mask is the most widely recognized oxygen mask in healthcare. It was
designed to deliver maximum oxygen concentrations above the 21% found in common room air. First
reported in 1919 as the Haldane Reservoir Oxygen Mask and later modified in the form of the BLB
Mask, this medical device has been used largely unmodified since the 1930’s. The non-rebreather mask
was designed with a series of one-way valves to direct gas from an oxygen reservoir into the mask on
inhalation while minimizing room air entrainment. During exhalation, two one-way valves located on
the side of the mask open to release the exhaled breath into the surrounding area. Due to a concern for
patient safety in the event that the source gas was interrupted or disconnected, one of the exhalation
valves is commonly removed to provide anti-suffocation protection. When one valve is removed, the
resulting non-valved port acts as a continuous room air entrainment port, significantly affecting
performance. Although manufactures often offer masks in both configurations, many organizations
specify this safety feature during procurement processes.
Mask with two exhalation valves
(circled in red)
Mask with one exhalation valve
removed for patient safety
(circled in red)
Performance
Many textbooks report oxygen delivery values for the non-rebreather mask at 80-95%, however these
values are non-referenced assumptions based on the original design. Published research have revealed
4
that these masks deliver far lower gas concentrations than assumed, primarily due to the removal of
one exhalation valve. Several studies have revealed that they significantly underperform to the extent
that patients inhale as much room air as oxygen. Because room air contains 21% oxygen, a 1:1 ratio of
room air and oxygen delivers a concentration of 60% to the patient. Garcia et al, CHEST 2005 (Appendix
1) revealed that a conventional non-rebreather mask operating at the prescribed oxygen flow of 8-10
Lpm resulted in 57-68% oxygen being delivered to the patient. A second study presented by John Earl,
RRT at the 2003 Association of American Respiratory Care (AARC) conference (Appendix 2) stated 5056% oxygen being delivered under similar conditions. These findings concluded that patients actually
inhale more air than oxygen during the inspiratory phase. A third abstract presented at the 2007 AARC
conference (Moody et al) revealed oxygen delivery between 53-71% despite using higher gas flows of
12-15 Lpm. These lower oxygen concentrations are based on the necessary removal of one exhalation
valve.
The conventional non-rebreather mask therefore delivers significantly lower oxygen levels despite
having the sole function of offering maximum oxygen concentrations to the patient during acute and
critical episodes of distress. While not all patients require maximum oxygen delivery, the most acute
crises require the ability to offer it. The result of using sub-therapeutic oxygen levels include further
deterioration of the patient’s condition leading to application of more advanced therapeutic regimens
by the attending healthcare professional or premature death. Subsequent treatment plans as a result of
inefficient oxygen delivery devices can include the application of more expensive equipment such as
non-invasive mechanical ventilation or endotracheal intubation and mechanical ventilation. These
approaches carry significant risk to the patient while incurring additional and unnecessary costs as well
as increased length of hospital stay.
The non-rebreather mask is stocked and used by all ambulances and hospitals worldwide despite the
documented performance statistics due to tradition, professional dogma and lack of affordable
alternatives. This poor performance is tolerated by those who subscribe to the belief that the device
delivers maximal oxygen concentration, often feeling secure that more advanced therapeutics are
available as a backup safety mechanism.
5
Medium Concentration or “Simple” Mask
The medium concentration or simple mask is a single function device which was designed to deliver a
lower amount of oxygen when 100% oxygen is not indicated. They are applied throughout the
healthcare industry to patients who are more stable and therefore less critical. These masks have a
simpler design in that they do not have a gas reservoir bag nor a series of one-way valves to direct gas
into and out of the mask during the respiratory cycle. The design allows more room air to entrain into
each inhaled breath, diluting the 100% oxygen fed into the mask. Traditional belief reports oxygen
delivery in the 40-60% range, depending on oxygen gas flow, which have been confirmed by the Garcia
studies. As with all single function products, the attending healthcare professional is forced to apply
additional devices offering higher concentrations if the patient’s condition deteriorates.
These masks are used in considerable numbers in the prehospital and hospital setting and are
commonly available in adult and child sizes.
A Medium Concentration or “Simple” Mask)
(Note: no exhalation valves on the side ports
and no reservoir bag)
6
Aerosol or Small Volume Nebulizer Mask
Aerosol or Small Volume Nebulizer Masks have the single function of aerosolizing liquid medications for
direct inhalation by patients with the intent of administering them directly to the bronchial mucosa.
Common medications include fast acting bronchodilators, steroids and some potent anti-biotics, which
are commonly applied in cases of acute or chronic respiratory disease. These devices are assembled
using three key parts; tubing to the oxygen flowmeter, a small volume nebulizer (SVN) and the mask
itself. There are no valves used to direct the medication flow and the mask typically has two large holes
on the sides for exhalation (see figure left, below).
Aerosol Mask with Small Volume Nebulizer Attached.
Note the large holes on each side of the mask.
Aerosol Mask with large bore tubing attached to
demonstrate loss of medication through side holes
Source: Dispersal of Respiratory Droplets With Open vs Closed Oxygen Delivery
Masks* Implications for the Transmission of Severe Acute Respiratory Syndrome
Ron Somogyi, BSc; Alex E. Vesely, MSc; Takafumi Azami, MD, PhD; David Preiss, MSc; Joseph
Fisher, MD; Joe Correia, RT; and Robert A. Fowler, MD, MS. (CHEST 2004; 125:1155–1157)
The SVN containing the medication is connected to the mask where the medication is aerosolized using
6-8 Lpm oxygen. Several nebulizer designs have defined individual products, however the mask
interface reduces any efficiency that the nebulizer may provide. Because the nebulizer operates on a
continuous source gas flow, a significant amount of medication is lost through the side ports during the
exhalation phase (see figure right, above), decreasing the amount of available medication to the patient.
The escaping effluent from the mask through the inhalation and exhalation phases of respiration
significantly exposes the surrounding healthcare workers to aerosolized medication and any exhaled
7
contagions that may be present. In addition, any effluent originating from the mask has the potential to
unnecessarily contaminate the surrounding surfaces.
As seen with non-rebreather mask and medium concentration masks, a significant amount of room air
is entrained through the side holes of inhalation, significantly lowering the amount of oxygen being
delivered to the patient. For patients that require a higher concentration of oxygen, the healthcare
provider must choose between removing a medium to high oxygen concentration device in place of a
aerosol mask that has the potential to compromise the patient. Medication administration can last for
20-30 minutes, after which the previous oxygen delivery device would be replaced on the patient.
This device (mask, nebulizer and tubing) are normally presented in adult and child sizes and prices may
approach that of a non-rebreather mask. These devices are designed for a single function of delivering
medications on a periodic basis. The typical patient is required to have oxygen delivery devices changed
between single function oxygen masks to medication delivery devices regularly through their hospital
admission, creating discomfort while increasing the potential for error.
8
Infection Control and Filtered Oxygen Masks
The primary strategy to protect healthcare workers from respiratory borne illnesses is through the use
of personal protective face masks, most commonly the N95 certified variety. Although these masks are
considered to be the standard for protecting the individuals who wear them, they are not designed nor
intended to be worn by patients who are suspected of carrying respiratory borne infectious diseases. In
fact, these masks are known to have a high inspiratory work of breathing to the degree that patients
suffering from respiratory distress may not be able to comfortably breathe while wearing them. They
are therefore contraindicated for patient use. Stable patients suspected of carrying infectious diseases
may be expected to don surgical mask when they are in public areas of the hospital, however the
requirement for oxygen delivery would conflict with the use of such devices. Therefore, contradictory
strategies collide when patients carrying infectious respiratory illnesses require oxygen therapy. While
international standards prescribe the placing of patients with confirmed diagnoses in negative pressure
isolation rooms, safe patient transport cannot be performed without exposing all surfaces along the
transport route to exhaled particulates.
The 2003 SARS outbreak led to the development and manufacture of oxygen masks designed to trap or
contain exhaled particles. The inability to provide filtration of exhaled respiratory particles on those
patients carrying infectious disease (confirmed or unknown) was an unrecognized danger until postSARS evaluations revealed that air currents generated by oxygen masks contributed to the spread of the
virus. Research by Somogyi (see attached article) and Hui both demonstrated that exhaled breaths
through oxygen masks aided by pressurized gas flow may allow particles to travel considerable
distances. As a result, many organizations began to implement filtered oxygen masks for patients
suspected of carrying a potentially infectious respiratory borne illness. The initial versions of these
masks were significantly more expensive than conventional oxygen masks and therefore were allocated
only upon confirmation that the healthcare providers were in danger of being exposed to potentially
infectious particles.
Several other masks incorporating filters at or near the exhalation port have become available, however
most models are variations of non-rebreather masks and very few of them are designed for multifunction use.
9
FLO2MAX 5-in-1 High Concentration Oxygen Mask
The FLO2MAX High Concentration Mask was designed to incorporate all the functionality of the above
mentioned masks while improving performance of any single function device. The FLO2MAX was
designed to act as a highly efficient non-rebreather mask, medium concentration mask and small
volume nebulizer mask while having the capability of filtering all exhaled particles and medications.
Designed to eliminate room air mixing during inhalation, the FLO2MAX device has no side ports
commonly seen on conventional oxygen masks and relies on a patented series of one way valves to
direct gas flow from the reservoir bag to the patient.
1. Filtration
Exhalation is directed through a 3M filter placed before the dedicated one-way valve, preventing release
of exposure to the surrounding staff and surfaces. The filter used in the FLO2MAX has a verified
Bacteria Filtration Efficiency (BFE) of 99.997% and Viral Filtration Efficiency of 99.993% and is made of
hydrophobic material. The placement of the filter medium upstream of the exhalation port ensures that
all exhaled particles are captured.
2/3. Medium and High Concentrations Easily Delivered
To prevent suffocation in the event of source gas failure, a calibrated anti-suffocation valve is designed
to open only if the gas in the reservoir has been evacuated. This mechanism also permits intentional
blending with room air in the event that the healthcare provider has achieved and wishes to maintain
acceptable blood oxygen levels. Tests have confirmed that a wide range of oxygen concentrations can
be attained to meet the needs of the healthcare provider and patient, far above the 60% experienced
with conventional non-rebreather masks. This allows the healthcare provider to assess the level of
acuity with greater accuracy and titrate the oxygen delivery through a wider spectrum of options. The
FLO2MAX therefore acts as both a medium concentration and a true high concentration delivery device.
10
4. Aerosolized Medications
Several types of small volume nebulizers are available to healthcare professionals, however they often
rely on the same type of open oxygen mask. The design of the FLO2MAX mask improves medication
delivery by preventing loss through the side holes, containing the medication for inhalation. Excess
medication is filtered out, minimizing exposure to healthcare professionals. For patients requiring
maximum gas concentration, a “Y” Connector (P/N 6500) was developed to allow both a reservoir and
nebulizer to be applied to the mask at the same time. This method allows nebulization of medication
while maximizing the gas concentration to the patient. Use of the “Y” Connector does not compromise
filtration of exhaled particles in any manner.
5. Metered Dose Medications
Released in January 2012, the FLO2MAX oxygen mask was updated to include a metered dose inhaler
port that allows “puffer” style medications to be administered directly into the reservoir component of
the mask, acting as a reservoir. This allows metered dose medications to be administered in an efficient
fashion without having to remove the mask from the patient’s face. Currently, this feature is available in
the large Adult (6100) and Small Adult (6105) models only.
Specialty Applications
Hospitals administer specialty gases (heliox, nitric oxide) for the purpose of relieving shortness of
breath. Maintaining a consistent concentration for effective use is difficult, can be costly and
complicated. Because of these difficulties, some have chosen to avoid this type of therapy or use a
conventional non-rebreather mask. The FLO2MAX mask allows easily application of high concentration
gas delivery with the ease and flow rates similar to conventional non-rebreather masks, with improved
results through less room air dilution.
The FLO2MAX 5-in-1 High Concentration Oxygen Mask is a simple substitution that requires minimal
instruction and training to apply. Combining several masks into one product decreases the amount of
product required to order, inventory and maintain as significantly reduces costs associated with the
11
removal of medical waste. They are available in three sizes (Large Adult, Small Adult and Child) and is
delivered complete with mask, reservoir and 2m crush proof tubing.
FLO2MAX 5-in-1 High Concentration
Oxygen Mask with reservoir
(as delivered)
FLO2MAX oxygen mask with small
volume nebulizer configuration
12
O-Mask 4-In-1 High Concentration Oxygen Mask
The O-Mask oxygen mask offers the same functionality as the FLO2MAX 5-in-1 High Concentration
Oxygen Mask with the exception that there is no integral filter within the valve assembly. The O-Mask
was designed to accept a filter of the healthcare provider’s choosing in the event that constant filtration
is required as part of their policy and procedure.
The O-Mask uses a simpler valve design to attain a full complement of oxygen concentrations from 2499% while offering the same convertibility to nebulization of medications. Also available in three sizes,
the same modifications proposed for the FLO2MAX are proposed for the O-Mask.
Because of the simpler design of the O-Mask and the lack of filter, the O-Mask has a lower cost than the
FLO2MAX series of masks. This series of mask offers improved healthcare delivery while reducing costs
associated with ordering, stocking and maintaining several separate SKU’s.
O-Mask in High Concentration oxygen
mask configuration (as delivered)
O-Mask with small volume
nebulizer configuration
O-Mask with small volume
nebulizer and expiratory filter
13
Appendix 1
THE OXYGEN CONCENTRATIONS DELIVERED BY DIFFERENT
OXYGEN THERAPY SYSTEMS
Chest 128 (4): 389S (2005)
Juan A. Garcia, MD*, Donna Gardner, RRT, David Vines, RRT, David Shelledy, PhD, Richard
Wettstein, PhD and Jay Peters, MD
University of Texas Health Science Center at San Antonio, San Antonio, TX
PURPOSE: To test the oxygen concentrations delivered by some of the available oxygen therapy
systems in normal subjects.
METHODS: Two different groups of ten healthy volunteers participated in two parts of this
study. Nasal cannula (NC) O2 delivery was tested in the first group Simple masks (SM) and nonrebreathing (NRB) masks were tested in the second group. Each subject had a # 8 French nasal
catheter inserted through a nare with the tip positioned immediately behind the uvula. The
nasal catheter’s proximal end was connected to a syringe stopcock "T" piece system with the
oxygen analyzer in line. Oxygen was administrated via the high flow NC (model ref 1600, Salter
Labs, Alvin, Ca) at flows 6-15 L/min. For the SM (Hudson RCI, Temecula, Ca), oxygen was
administer at 6-12 L/m, and for the NRB mask (Hudson RCI, Temecula, Ca), the flow was 6-15
L/min. At each different oxygen flow the subject breathed normally for five minutes. Using the
oxygen sampling system, three gas samples (60 mL each) were withdrawn from the pharynx
during inspiration and directed to the oxygen analyzer. The average FiO2 delivered was
recorded for each one of the oxygen flows administered with the different systems.
RESULTS: Table 1 shows the means ± SD for each device. Figure 1 shows the comparison
between the different devices.
CONCLUSION: The HFNC was able to provide higher mean FiO2 than the SM at flows of 6-10
L/min; at 12 L/min the delivered FiO2 was equal. HFNC compared to NRB mask delivered equal
mean FiO2 at flows 8-15 L/min, and was superior at 6 L/min. Both masks will deliver less variable
FiO2 than HFNC.
CLINICAL IMPLICATIONS: If needed, HFNC can deliver similar FiO2 than NRB mask. Medical
personnel should be aware of the high FiO2 variability this system may deliver. When switching
from HFNC to SM, a higher O2 flow should be selected to achieve similar delivered FiO2. The
simple rule for estimating delivered FiO2 with different oxygen systems is not accurate.
14
Table 1
Nasal
cannula FiO2
O2 flow % (mean ± Range
(L/min)
SD)
FiO2 %
Simple
Mask FiO2
% (mean ±
SD)
NonRange rebreather FiO2 Range
FiO2 % % (mean ± SD) FiO2 %
Predicted
FiO2 %
6
54 ± 13
35-89
43 ± 2.6
38-47
45 ± 2.9
40-49
45
8
58 ± 14
33-87
41 ±2.6
37-47
57 ± 4.6
51-65
53
10
66 ± 13
40-88
57 ± 3
52-63
68 ± 2.3
64-71
61
12
69± 13
37-93
69 ± 3.3
64-74
68 ± 2.7
64-73
69
15
75 ± 13
39-98
Not tested
74 ± 2.4
68-77
77
DISCLOSURE: Juan Garcia, None.
15
Appendix 2
DELIVERY OF HIGH FIO2
Author: John W. Earl RRT, BS
Director Respiratory Care Service (retired)
VA Medical Center, White River Jct. Vermont 05009
Objectives. To determine oxygen flow rate needed to provide an FiO2 greater than 90% using a nonrebreather mask (NRB), simple mask (SM), and a simple mask with side ports taped (SMT).
Methods: Flow rates of 10, 15, 30, 45, and 60 LM were tested. Each test was performed using a
healthy subject wearing a firmly secured mask while performing quiet breathing at a rate of 12-18
breaths per minute at tidal volumes of 300-500 mls. Each test was performed for 5 minutes. A fiveminute time frame was established by having participant perform an N2 washout (<1.5% N2) within 3
minutes. Nitrogen (N2) washout method was used to determine the partial pressure of oxygen (PO2)
contained in the lungs following each test. The study was performed using Sensor Medics V-Max ® N2
washout system. Calibration was performed per manufacturers recommendations. N2 washout
measurements were taken following a final deep breath exhaled into a closed system. Each test was
separated by a 10-minute interval per previous established criteria.
Results: Expired PO2:
Litre Flow
FiO2
(Simple Mask )
FiO2
(Non-breather)
10 Lpm
51
15 Lpm
51
30 Lpm
55
45 Lpm
73
60 Lpm
86
50
56
77
78
89
Simple Mask Taped
to face = 93
Discussion: 60 LM came closest to providing >90% FiO2. It is apparent that a simple mask can be
almost as effective as a NRB mask using high flow, and more so with ports taped shut. Taping or
providing reservoirs to the side ports of mask works well to increase FiO2 and does not incur
backpressure or increased work of breathing. It must also be noted that resting minute ventilation was
performed which is rarely observed of patients suffering SOB from fluid filled lungs or pneumonia.
Conclusions: It would seem prudent to provide a taped simple or NRB mask operating above 60 LM
to ensure maximum supply of FiO2 over the short term. Flow meters will deliver 90 LM on flush
setting. Current thinking that a NRB mask running at 15 Lm is an acceptable way to deliver high FIO 2
is not valid and should be revised.
American Association of Respiratory Care Open Forum Abstracts (2003)
16
Appendix 3
PERCEPTIONS OF NON-REBREATHING MASK FIO2 VS. ESTIMATED FIO2 USING THE REVERSE ALVEOLAR AIR
EQUATION
K. Moody1, C. Trippe1, D. Pursley1, A. Light1
Background: We surveyed 38 randomly selected RRTs and RNs and asked them the following question: “What
FIO2 does a non-rebreathing mask (NRBM) deliver to a patient’s airway at 12-15 L/m?” The 20 RRTs had an
average of 20 years of experience, while the 18 RNs had a mean of 12 years of experience. On average, the RNs
said the NRBM gave 96% while the RRTs believed that it gave 84%, with 32 of the respondents answering “90100%”. However, the reality is that “modern disposable non-rebreathers normally do not provide much more
than approximately 70% oxygen” (Wilkins, et al., 2003, p. 840). Because the disposable NRBM is actually a low
flow oxygen system, we agree that it delivers a more moderate FIO 2 and thought it would be interesting to
calculate the estimated FIO2 from the PaO2 of persons breathing oxygen from this device. Method: We
recruited ten healthy, non-smoking, normothermic volunteers between 21-29 years of age and had them
breathe oxygen from a NRBM at either 12 L/m or 15 L/m. The subjects were told to relax and breathe normally
for a period of fifteen minutes. At the end of the fifteen minute period, we performed a radial artery blood gas
and measured PaCO2 and PaO2 using an IL GEM 3000 blood gas analyzer. Assuming our subjects had normal
cardiopulmonary anatomy and physiology, we estimated PAO 2 by dividing PaO2 by a normal a/A ratio of 0.9 to
reflect a 10% higher partial pressure of oxygen in the alveolus than in the arterial blood (Wilkins, et al., 2003, p.
231). Knowing approximate alveolar partial pressure of oxygen, we then calculated FIO 2 based on what we call
the reverse alveolar air equation: FIO2 = *(PaO2 ÷ 0.9) + (PaCO2 • 1.25)+ ÷ (PB - 47).
Results: Our results indicate that the NRBM delivered an average FIO2 of 0.60 in young, healthy non-smokers.
FIO2 varied from 0.53 to 0.71 in our ten subjects.
Conclusion: Contrary to the opinion of the healthcare professionals in our survey, the NBRM tended to deliver
more moderate concentrations of oxygen in our young, healthy volunteers. Patients with high minute
ventilation placed on a NRBM will theoretically receive an even lower tracheal FIO2 due to additional dilution of
room air with oxygen. In this situation, high flow devices which meet or exceed the patient’s inspiratory flow
demand may provide a more suitable method of delivery to give high concentrations of oxygen. Wilkins, et al.
(2003). Egan's Fundamentals of Respiratory Care, 8th Edition. Mosby.
Age/
Gender
28/Female
23/Female
29/Male
22/Male
25/Male
25/Female
26/Female
21/Male
26/Female
25/Male
L/M
12
12
12
12
12
15
15
15
15
15
Height
5'8"
5'7"
6'2"
5'7"
5'9"
5'6"
5'1"
6'1"
5'9"
6'2"
VE
(L/m)
6.41
8.10
6.40
6.55
7.45
6.17
11.2
12.8
8.90
11.6
VT (mL)
712
810
582
595
497
560
800
853
890
967
f
9
10
11
11
15
11
14
15
10
12
PB
(mmHg)
PaO
(mmHg)
PaCO
(mmHg)
730
730
730
730
730
730
730
730
730
730
292
299
301
316
293
396
397
304
335
349
33
37
40
42
42
39
40
34
37
41
2
2
Estimated
FIO2
0.53
0.55
0.56
0.59
0.55
0.71
0.71
0.55
0.61
0.64
American Association of Respiratory Care Open Forum Abstracts (2007)
17