Pulse Oximeter Validation Study for the Perin Health Patch
Conditions: Hypoxia
Sponsor: Perin Health Devices

Date last updated: October 24, 2024 
Date v1.0 implemented: January 1, 1986 
UCSF IRB: 21-35637 
WHO Protocol ID: ERC.0004026 
Protocol: Basic pulse oximeter hypoxemia (lab) 
performance study 
Citation: UCSF Hypoxia Lab, Protocol for basic pulse oximeter hypoxia performance study. May 
2024. https://openoximetry.org/study-protocols/  
Abstract/Description 
Pulse oximeters were introduced clinically around 1982 and are routine in most clinical settings 
including surgery, recovery, intensive care, and other special applications where patients may 
be at risk of inadequate oxygenation or ventilation. There are numerous manufacturers of these 
devices. The instruments intended for clinical use are required by the US FDA and multiple 
other bodies to be tested per ISO 80601-2-61 over the range of SpO2 70-100%. The 
instruments are calibrated by design at the factory and generally do not need or permit 
recalibration. 
This study protocol was started in 1986 to determine the performance of pulse oximeters and to 
help generate data to improve performance and safety. More than 3000 subjects have been 
studied, using more than 100 different manufacturers’ devices. Because of continuing 
improvements in pulse oximeter design, continuing introduction of new products to the market, 
and ongoing challenges in performance, the testing is still needed to ensure and improve safety 
and performance of pulse oximeters.  

Update history 
October 24, 2024 - Updated sampling to more accurately describe practice of blood gas sample 
analysis 
September 26, 2024 - Updated Section 4 to specify that all fingers on either hand, including in 
the presence of an arterial line, are used to test pulse oximeter performance. Also updated our 
timing for achieving plateau stability  
June 10, 2024 - Removed methylene blue as an exclusion criteria 
May 28, 2024 - Updated Step 1 of the protocol to include our recruitment practices (i.e. use of 
the UCSF Clinical and Translational Science Institute (CTSI) Participant Recruitment Program 
(PRP), TrialFacts as well as other general recruitment strategies). Other minor edits to the steps 
were made to reflect the current practices of the Hypoxia Lab in terms of arterial line insertion, 
blood sampling, assessing participants’ vital signs, control of the gas mixtures, etc. 
May 23, 2024 - Updated protocol for running arterial blood samples on ABL machines (see 
bullet point 8 of steps). Also, added the Nihon Kohden and Philips IntelliVue as reference 
devices. 
May 17, 2024 - Added that we quantify skin color on areas of the skin free of any product, 
including sunscreen, makeup, etc. 
April 3, 2024 - Added the WHO Protocol ID: ERC.0004026 to page 1 
February 5, 2024 - Included that we record observed skin tone of subjects on the day that they 
complete the study. 
January 29, 2024 - Updated step 4 to say that we record averaging time for reference devices 
and any changes to the settings. Also, specified the averaging time settings for the references in 
the materials section. 
January 25, 2024 - Updated exclusion criteria with the methylene blue exclusion
 

Guidelines 
This protocol was designed by the UCSF Hypoxia Lab and was the original model for the FDA 
and later ISO80601-2-61 requirements and standards for pulse oximetry performance. We 
continuously update this protocol with the intention of meeting and exceeding requirements by 
ISO 14155, ISO 80601-2-61 and FDA 510k as they evolve. 
Before starting 
Ensure IRB approval, consent, forms meet ISO15155 and are approved by IRB. Ensure safety 
protocols, trained personnel (anesthesia and/or critical care) and access to emergency 
resuscitation equipment are immediately present, checked and functioning. All equipment must 
be calibrated in accordance with manufacturers’ specifications. This includes oxygen and CO2 
gas analyzers as well as blood gas analyzers and of course emergency equipment. Ambient 
temperature, humidity and barometric pressure must be measured and accounted for.  
Safety warnings 
This protocol involves placing arterial catheters and administering hypoxic gas mixtures. This 
protocol should only be implemented by personnel with relevant experience and training, safety 
equipment and safety protocols.  
Materials 
1x Mass spectrophotometer CO2 
1x Mass spectrophotometer O2 
2-3x Hemoximeter(s) (ABL90, Radiometer - or equivalent) 
22g arterial cannulas and associated transducers 
Multimodal automated vitals sign monitor with alarms (BP, ECG, HR, RR, SpO2, ABP) 
Reference pulse oximeters  
Nellcor PM1000N, set to default averaging time 
Masimo Radical-97 (x2), set to default averaging time 
Nihon Kohden, set to default averaging time 
Philips A01 Philips FAST SpO2 Module, set to default averaging time 
National Instruments Labview software 
National Instruments Labview digital to analog converters 
Computer 
Gas flow control system for nitrogen, air, oxygen and carbon dioxide 
Heparinized 3mL syringes 
Colorimeters/melaninometers/spectrophotometers 

Study Design 
1.​ Subject recruitment & diversity  
a.​ 10-14 healthy adult (18-50yo) volunteer paid participants are recruited to ensure 
adequate diversity and data sample size. This was the default for most studies up 
until 2022. Starting in 2022, we aimed to recruit at least 24 participants per study 
cohort and in some cases >100 depending on study design 
b.​ We typically recruit 10-20% more subjects than is required to power the study, to 
account for data loss due to participant drop out or data quality, among other 
factors.  
c.​ Participant data is recorded including baseline vital signs, weight, skin color and 
finger diameters   
d.​ Skin color  
i.​
Skin color assessment is performed by one or more clinical research 
coordinators and/or the study physician assigning for each subject a skin 
color category using two visual-analogue printed color scales - perceived 
Fitzpatrick Scale (pFP) and Monk Skin Tone (MST) Scale. The assessed 
portion of skin is cleaned of any product, including sunscreen, makeup, et 
cetera. When using the pFP or MST, the color scale next to the patient's 
skin (forehead, ear, nose, arm, and fingers). Skin color is also assessed 
by measuring color with a Konica Minolta 700d skin spectrophotometer 
that reports color in the LAB colorspace (and is used to calculate 
individual typology angle (ITA) - a surrogate for skin melanin content). The 
spectrophotometer is applied to the skin in a manner that uses minimal 
force to ensure circumferential contact. The device shines visible light 
onto a non-identifiable 3mm section of skin, and measures the color of 
reflected light. Skin color observed on the day of the study should be 
recorded for each new data entry. We aim to recruit ~30% of study 
participants per device tested in each of 3 bins of skin color defined by the 
Monk Skin Tone Scale (ABC, DEFG, HIJ). Given known limitations in 
subjective skin color scales, we will also objectively measure ITA and 
ensure 30% of participants have an ITA<-30, a previously established 
cutoff for dark skin pigment. We also aim to ensure half of subjects in the 
‘dark pigment’ category have an ITA < -50. Both ITA and MST are done 
on the forehead and at the site of pulse oximeter placement. We collect 
data using skin melaninometry, colorimetry and spectrophotometry to 
quantify skin color on areas of the skin free of any product, including 
sunscreen, makeup, et cetera. Protocol updates are in progress to better 
define and recruit adequate diversity for this study protocol (See Skin 
Color Quantification Protocol separately). 

e.​ We collaborate with the UCSF Clinical and Translational Science Institute (CTSI) 
Participant Recruitment Program (PRP) to ensure best practices. This includes 
optimizing study recruitment materials and strategies. Through the PRP, the 
study is being advertised via social media (Facebook ad posts, Craigslist, etc.) 
and through the electronic health record system at UCSF. We also utilize a 
specialized recruitment service vendor. For equity among interested participants, 
information is sent both electronically and through paper mail. Subjects new to 
the study will also be recruited via flyers posted on university campuses in the 
San Francisco Bay Area or emailed electronically to student based affinity 
groups. Some subjects may also be recruited via word of mouth from previous 
study subjects. 
f.​
Inclusion criteria: 
i.​
The subject is aged ≥ 18 and < 50. 
ii.​
The subject is in good general health with no evidence of any medical 
problems. 
iii.​
The subject is fluent in both written and spoken English (we are actively 
working to expand access to this study to subjects who prefer other 
languages). 
iv.​
The subject has provided informed consent and is willing to comply with 
the study procedures. 
g.​ Exclusion criteria: 
i.​
The subject has a BMI > 35.    
ii.​
The subject has a known history of heart disease, lung disease, kidney 
disease or liver disease. 
iii.​
Diagnosis of asthma, sleep apnea, or use of CPAP.   
iv.​
Subject has diabetes. 
v.​
Subject has a clotting disorder. 
vi.​
The subject a hemoglobinopathy or history of anemia, per subject report 
or the first blood sample, that in the opinion of the investigator, would 
make them unsuitable for study participation. 
vii.​
The subject has any other serious systemic illness.   
viii.​
The subject is a current smoker. 
ix.​
Any injury, deformity, or abnormality at the sensor sites that in the opinion 
of the investigators’ would interfere with the sensors working correctly.   
x.​
The subject has a history of fainting or vasovagal response.   
xi.​
The subject has a history of sensitivity to local anesthesia.   
xii.​
The subject has a diagnosis of Raynaud’s disease.   
xiii.​
The subject has unacceptable collateral circulation based on an exam by 
the investigator (Allen’s test).   
xiv.​
The subject is pregnant, lactating or trying to get pregnant. 

xv.
The subject is unable or unwilling to provide informed consent, or is
unable or unwilling to comply with study procedures.
xvi.
The subject has any other condition, which in the opinion of the
investigators’ would make them unsuitable for the study.
xvii.
Subjects are screened for COVID-19 before coming in for testing. Fully
vaccinated subjects are recruited for this study. Subjects will be asked if
they have any symptoms related to COVID-19 and if they have any
symptoms or are sick they cannot participate and a temperature will be
taken before the study.
2.
Arterial catheter insertion
a.
After ensuring subjects do not have drug allergies, the study physician uses local
anesthesia (1mL of 1% lidocaine injected subcutaneously via 25-gauge needle)
and sterile technique, to place a 22-gauge catheter in one radial artery. An Allen's
test and/or sonographic identification of patent ulnar and radial arteries are
performed prior to catheter insertion in order to maximize safety.
3.
Monitoring
a.
Oxygen saturation (SpO2), heart rate, blood pressure, respiratory rate and
temperature are recorded at baseline. Heart rate, ECG, SpO2, blood pressure
and respiratory rate are recorded throughout the study either at time intervals or
continuously in accordance with ISO80601-2-61.
4.
SpO2 probe placement site selection
a.
Probes are placed on sites selected by randomization or sponsor preference,
with at least one device capable of measuring pulsatility amplitude (i.e.,
sometimes commonly referred to as perfusion index) on the same hand and/or
adjacent digit. All fingers, including the thumb and pinky, are used to test the
performance of pulse oximeters, and, in some cases, placement occurs on the
same side as the arterial line. One or both of the lab’s FDA 510(k)/CE reference
oximeters are always used for all studies.
i.
After Fall 2022 UCSF Hypoxia Lab is using Nellcor PM1000N with the
DS-100A1 Adult Reusable SpO2 Sensor and Masimo Radical-97 with the
RD Set DCl Adult Reusable Sensor 3ft purchased in Fall 2022.
Depending on study design, the Masimo Adult Reusable Ear Sensor or
Nellcor Max-Fast Forehead Sensor may also be used.
ii.
Prior to Fall 2022 UCSF Hypoxia Lab reference pulse oximeters were
Nellcor N-595 and Masimo Rad 7 non-color, non-touch screen.
b.
Adjacent finger pulse oximeter probes are optically isolated from each other
using a custom isolation divider made of molded kydex and a modified Masimo
disposable optical light shield (Image 1). Averaging time for devices is also
recorded on the day of the study, if changes to the settings are made. In general,
devices are kept on default averaging time settings, unless otherwise noted.

5.​ Patient positioning  
a.​ Subjects lie semi-supine and breathe through a mouthpiece while the nose is 
obstructed by a nose clip. A viral filter is placed in the breathing circuit to prevent 
cross contamination between subjects and/or study personnel. Subjects are 
instructed to increase minute ventilation during all runs, breathing at ~20 breaths 
per minute with 2-3 times deeper breaths than baseline to speed alveolar gas 
equilibration and provide frequent end tidal samples for analysis by mass 
spectrometry and computer calculation of saturation. 1-4% CO2 is added to 
inspired air to prevent significant hypocapnia. A pneumotach is sometimes used 
to measure minute ventilation and respiratory rate. This flow sensor is used in 
accordance with its manufacturer approved labeling as a component of the 
breathing circuit.  
b.​ When pulse oximeters are tested on the extremities, those extremities are at or 
more commonly below the level of the phlebostatic axis. Depending on study 
objectives, if multiple devices are being tested on adjacent digits, then shielding 
may be placed between devices to prevent device-to-device visible and IR light 
contamination. Shielding from ambient laboratory lighting is not routinely done. 
c.​ By default we do not warm the hands or fingers of study participants. For devices 
tested as part of the OpenOximetry.org project, hand warming was not routinely 
performed unless the study was shared with a sponsoring manufacturer who 
requested warming be done. Warming was performed with a commercially 
available consumer grade heating pad placed under or around the hand. 
6.​ Controlling hypoxemia   
a.​ (Figure - Desaturation Step Protocols) The study investigator (anesthesiologists 
and/or critical care physician MD) controls the delivered oxygen concentration by 
adjusting nitrogen, oxygen, carbon dioxide and room air flow meters via a custom 
breathing circuit setup to deliver a desired oxygen concentration. Gas 
concentrations are adjusted to achieve different steady state levels of hypoxemia 
from 70-100% (due to variability in subject physiology and device performance 
accuracy this may sometimes result in saturations in the 65-70% range). A 
computer program displays a breath by breath, calculated arterial oxygen 
saturation, (cSaO2) of the study subject. The cSaO2 is computed from 
end-expired PO2 and PCO2 as determined by mass spectrometer gas analysis 
(AEI Technologies, S3A - 0.01% accuracy, calibrated daily). This information 
permits the inspired gas mixture of air, plus CO2 and nitrogen, to be adjusted by 
an operator watching the value computed after each expiration on an analog 
meter (of note this cSaO2 is not used in place of measured SaO2 by 
hemoximetry). This computer-estimated saturation is adjusted by the operator to 
one of 6 levels of predicted saturation. The calculated oxygen saturation and gas 
flows are held constant, and SpO2 values are allowed to reach a steady plateau.  

7.
Plateau Stability
a.
The time period for stability is at least 60 seconds but typically 60-180 seconds
prior to sampling at each plateau (of note, in patients with lower perfusion, the
plateau may be held for longer ~120-240 seconds to ensure adequate SpO2
stabilization). The 6 target plateaus are achieved in two separate desaturation
'runs' as outlined in the supplementary figure. Each "run" lasts ~15 min. Plateaus
are typically sought to be evenly distributed among the three SaO2 decades of
70% to 80%, 80% to 90% and 90% to 100%.
b.
A calculated saturation (ScO2) based on end tidal O2, end tidal CO2, assumed
A-a gradient, and p50, is used in addition to SaO2 and SpO2 data from reference
devices to estimate plateau stability in real time. Study investigator visually
inspects ScO2 and reference device SpO2 curves in real time to ensure stable
plateaus prior to and during sampling. A custom configuration of labview
interprets ScO2 and SpO2 of reference devices in real time to calculate slope for
the past 20 seconds and predict SpO2 change over the next 1 minute. A green
light is displayed to indicate if predicted SpO2 change is < 2% and ScO2 change
is < 2%. A red light is otherwise displayed. Generally, these indicators are used
to determine sampling along with the discretion of the study investigator
c.
SaO2 from ABLs is also analyzed in real time in Labview, and a red indicator is
displayed if SaO2 changes by more than 1.5% between samples, indicating
instability
8.
Blood sampling
a.
During controlled hypoxemia, up to 30 1.5-2 mL arterial blood samples from each
subject (<70mL total) are obtained at different steady-state levels of hypoxemia
from 70-100%. Prior to the study sample being drawn, a discard sample (~0.5 -
1mL) of ~2-3x the circuit dead space is drawn. Blood samples are withdrawn in
<5 seconds into a 3mL heparinized syringe. Samples are visually inspected, air
bubbles are expelled through a vented tip cap, and the syringe is gently mixed
(by inverting and rolling). Syringes contain lyophilized balanced Li-heparin with a
goal of 20IU/mL blood (liquid heparin may impact/dilute results including pO2).
Samples are drawn after stability as measured by reference oximeter SpO2
(Nellcor PM1000N with DS-100A1 Adult Reusable SpO2 Sensor, Masimo
Radical 97 with RD Set DCl Adult Reusable Sensor 3ft) and calculated saturation
as outlined above. Blood samples obtained from the arterial line are immediately
analyzed by co-oximetry (Radiometer ABL90 Flex Plus) to determine true
functional saturation (SaO2) value. If sample is not run immediately (e.g.,
running the sample on a third ABL90 to confirm results) then it is gently mixed
via vortex prior to analyzing. Readings from the test pulse oximeters are
recorded and compared to these functional saturation (SaO2) "gold-standard"
blood values. (Note: Some manufacturers and labs have been known to use

fractional saturation O2Hb instead of functional saturation for calibration). Up to 
three blood gas analyzer machines are used in parallel to confirm readings 
(ABL90 Flex plus, Radiometer). A single blood sample is initially run on two of the 
ABLs; if there is >0.5% difference in the SaO2 values, the sample is run a third 
time on an additional ABL it was not originally run on. Amongst the three, if two of 
the SaO2 values are not within 0.5% of each other, then that data point is 
excluded during data cleaning. If two SaO2 values are within 0.5% then the 
average of those two results are recorded as the sample’s SaO2.  
9.​ Return to baseline  
a.​ Inspired oxygen is abruptly changed when blood sampling is completed, either to 
a lower level or, at the final plateau of each run, to 100% oxygen.  At the end of 
the study, the arterial line is removed and pressure is applied to the site for 10 
minutes or until hemostasis. Vital signs are repeated at the end of each study. 
Subjects are monitored in the lab for at least 15 minutes after each study to 
ensure hemostasis and absence of symptoms. 
b.​ Coban wrap is applied to subject wrist and subjects are instructed to remove after 
an hour. Subjects are advised to avoid strenuous exercise or weight lifting for the 
rest of the day.  
10.​Carbon dioxide (CO2 ) control  
a.​ For most pulse oximeter hypoxia studies, CO2 is delivered into the circuit by the 
investigator to maintain normal end tidal and arterial CO2 to prevent symptomatic 
hypocapnia and promote regular respiratory pattern. For some studies, hyper- 
and hypocapnia are targeted and controlled as follows. To reduce PCO2, subjects 
voluntarily hyperventilate during the test, to an end tidal PCO2 goal of 25 mmHg. 
The study doctor observes end-tidal PCO2 values on a breath-by-breath basis 
using a CO2 gas analyzer (AEI Technologies, CD-3A and P61-B - calibrated 
daily, Accuracy: ± 0.02% CO2 0 – 7% CO2) and directs to the subjects breathing 
to achieve a PCO2 of the desired level.  For higher PCO2 values, CO2 is metered 
into the breathing circuit to increase end tidal PCO2 by 10-15 mmHg from 
baseline.  These interventions each last 6-8 minutes. 
11.​Pulsatility/Perfusion assessment 
a.​ By default we do not alter pulsatility or perfusion of participants. For some 
studies, peripheral vascular perfusion is modified by 1) elevation of the hand plus 
systemic hypotension with nitroprusside if needed; 2) clamp compression of the 
brachial artery (often avoided due to potential venous compression); 3) brachial 
cuff inflation (often avoided due to venous compression); 4) intraarterial 
norepinephrine or phenylephrine (NE); 5) cooling/warming the room or patient’s 
extremity (with forced air cooler and liquid cooling systems) 6) by placing their 
hand in an ice bucket or controlled cooling device. Perfusion is measured using a 
Nellcor PM1000N pulsatility amplitude signal output, Masimo Radical-97 

perfusion index, and a custom raw PPG device as ‘reference’ perfusion devices 
(expanded protocol on perfusion is coming soon). One reference device is placed 
on each hand so that pulsatility data are available for at least each hand. Prior to 
initiation of each study, perfusion dates are recorded with one reference device 
for all fingers on both hands. When testing study devices that do not measure 
perfusion, a reference device is placed on the same hand, and when possible on 
an adjacent finger to approximate perfusion for the study device digit. This 
technique has limitations that are currently being optimized.  
12.​Motion  
a.​ By default for most studies subjects are asked to remain as motionless as 
possible. For some studies, affixing the subject’s arm to a motion machine and 
rhythmically moving the arm in a repeatable and controlled manner during the 
study is used to evaluate impact of motion on performance (expanded protocol 
on motion is coming soon).  Depending on study objectives, other methods may 
be used to induce or simulate motion, though this is not part of the standard 
protocol. 
13.​Data Recording & Cleaning 
a.​ Hemoximeter (SaO2) data from the ABLs, SpO2 data from reference oximeters, 
ECG waveform  (Philips Intellivue MX 750), arterial line waveform (Philips 
Intellivue MX 750), RR  (Philips Intellivue MX 750), EtO2 (AEI Technologies), 
S3A, EtCO2 (AEI Technologies, CD-3A and P61-B) are routed directly into 
custom configuration of Labview (National Instruments, Austin, Tx) 
b.​ Data are used to estimate calculated oxygen saturation (ScO2) (as described 
above) at 1hz 
c.​ SaO2 and SpO2 data from the reference devices (Nellcor PM1000N and 
Masimo Rad-97) are cleaned using an algorithm that checks for plateau 
stability. Data points are flagged if their difference from both the previous and 
next readings exceeds a predefined threshold. If the data point is the first or 
last in the session, the difference from the subsequent or preceding reading, 
respectively, will be checked. The threshold for flagging SaO2 data points is 
1.5, while the threshold for SpO2 data from the references is 2. Any data 
point flagged for either SaO2 or SpO2 from Nellcor PM1000N will be 
excluded from the analysis and undergoes manual review. 
d.​ Finally, sessions will be flagged for review if they contain at least one data 
point from devices under test that meets any of the following criteria: 1) an 
absolute bias greater than 20, 2) a bias difference of ≥5 compared to both the 
previous and next samples, or 3) an SaO2 value of 80% or higher with an 
absolute bias greater than 10. Flagged sessions will be reviewed manually by 
the Principal Investigator, and data points will be excluded based on their 

instructions. These criteria were determined after manual analysis of >600 
sessions (>10,000 data points).  
e.​ For some studies, sponsors may request to record the subject's face during the 
desaturation study. These recordings will be used to determine if blood oxygen 
saturation can be determined through facial recordings. These recordings will be 
kept by the sponsor for a period of 2 years after completion of the study. 
Timestamps will be used to correlate to the subject number.   
f.​
For some studies, the protocol may video record the hands and/or wrists through 
the study period. This is to record data from pulse oximeters with displays on the 
wrist and hands (i.e. to record the data output directly from the display). This 
information would be kept by sponsors/investigators for the length of the IRB 
approved period. The subject faces would not be recorded at any point for this 
purpose.  Timestamps from the video recording will be used to correlate video 
recordings to the subject number.   
 
 
  
                 
Device Calibration 
 
1.​ Konica Minolta  
a.​ Device undergoes yearly factory calibration. 
b.​ Before data collection, the device is turned on and, when prompted, zero 
calibration is completed with the zero calibration cap/cylinder purchased from 
Konica Minolta. White calibration is then completed with the white calibration cap 
when prompted by software.  
2.​ Radiometer ABL90 FLEX - completed the day before each study 
a.​ Test is completed to calculate machine’s hemolyzer frequency and ensure ensure 
it is within acceptable range 
b.​ Calibration performed 
c.​ Iternal quality controls 1, 2 & 3 performed 
d.​ Ampule (external) quality controls 1, 2 & 3 performed 
e.​ tHb calibration performed 
f.​
If at any point calibrations or QCs do not pass, consumables are changed and/or 
a Radiometer representative is contacted to fix the issue. ABLs are only used 
once they pass all calibrations and QCs. 

Image 1u 
Study participant, UCSF Hypoxia Research Lab, finger shielding of adjacent devices with kydex 
plastic mold, lined with Masimo finger shield sleeves (Note: top left open for data recording; for 
handheld and tabletop devices, full circumference finger shields may be used).

References 
Errors in 14 pulse oximeters during profound hypoxia. 
Severinghaus JW, Naifeh KH, Koh SO. 
J Clin Monit. 1989 Apr;5(2):72-81. doi: 10.1007/BF01617877. 
PMID: 2723709 
 
Accuracy of response of six pulse oximeters to profound hypoxia. 
Severinghaus JW, Naifeh KH. 
Anesthesiology. 1987 Oct;67(4):551-8. doi: 10.1097/00000542-198710000-00017. 
PMID: 3662082 
 
Improved accuracy of methemoglobin detection by pulse CO-oximetry during hypoxia. 
Feiner JR, Bickler PE. 
Anesth Analg. 2010 Nov;111(5):1160-7. doi: 10.1213/ANE.0b013e3181f46da8. Epub 2010 
Sep 14. 
PMID: 20841412 
  
Accuracy of methemoglobin detection by pulse CO-oximetry during hypoxia. 
Feiner JR, Bickler PE, Mannheimer PD. 
Anesth Analg. 2010 Jul;111(1):143-8. doi: 10.1213/ANE.0b013e3181c91bb6. Epub 2009 Dec 
10. 
PMID: 20007731 
 
Dark skin decreases the accuracy of pulse oximeters at low oxygen saturation: the effects of 
oximeter probe type and gender. 
Feiner JR, Severinghaus JW, Bickler PE. 
Anesth Analg. 2007 Dec;105(6 Suppl):S18-23, tables of contents. doi: 
10.1213/01.ane.0000285988.35174.d9. 
PMID: 18048893 
 
Effects of skin pigmentation on pulse oximeter accuracy at low saturation. 
Bickler PE, Feiner JR, Severinghaus JW. 
Anesthesiology. 2005 Apr;102(4):715-9. doi: 10.1097/00000542-200504000-00004. 
PMID: 15791098 Clinical Trial. 
 
Pulse oximeter failure thresholds in hypotension and vasoconstriction. 
Severinghaus JW, Spellman MJ Jr. 
Anesthesiology. 1990 Sep;73(3):532-7. doi: 10.1097/00000542-199009000-00025. 
PMID: 2393137 
 
Effect of anemia on pulse oximeter accuracy at low saturation. 
Severinghaus JW, Koh SO. 
J Clin Monit. 1990 Apr;6(2):85-8. doi: 10.1007/BF02828282. 
PMID: 2352007 

Comparison of Transcranial Doppler and Ultrasound-Tagged Near Infrared Spectroscopy for 
Measuring Relative Changes in Cerebral Blood Flow in Human Subjects. 
Lipnick MS, Cahill EA, Feiner JR, Bickler PE. 
Anesth Analg. 2018 Feb;126(2):579-587. doi: 10.1213/ANE.0000000000002590. 
PMID: 29189269 
Preanalytical considerations in blood gas analysis 
Geoffrey Baid, Biochem Med. 2013; 23(1):19-27 
Low perfusion and missed diagnosis of hypoxemia by pulse oximetry in darkly pigmented 
skin: A prospective study 
M Koa Gudelunas, Michael Lipnick, Carolyn Hendrickson, Sky Vanderburg, Bunmi Okunlola, 
Isabella Auchus, John R. Feiner, Philip E. Bickler 
MedRxiv, 2022. doi: https://doi.org/10.1101/2022.10.19.22281282 
Agache 2017 Measuring the Skin, Chapter 6 “The Measurement of Skin Color”:  
Chau et al 2019 Cutaneous Colorimetry as Gold Standard for Skin Color Measurement:  
Visscher 2017 Skin color and pigmentation in ethnic skin   
Wilkes et al 2015 Fitzpatrick Skin Type, Individual Typology Angle, and Melanin Index in an  
African Population: Steps Toward Universally Applicable Skin Photosensitivity Assessments