diferentes respuestas spo2 hiportermia.pdf

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136 CANADIANJOURNALOF ANESTHESIA

Purpose:Several new pulse oximeters using updated algorithms

are marketed as being resistant to motion and hypoperfusion.

The purpose of this study was to compare the performance

of three pulse oximeters under conditions of hypothermia and

altered perfusion.

Methods: Ten male volunteers were enrolled in this study

after Institutional approval and obtaining informed consent.The probe of the Dolphin 2100, Nellcor N-595, or Masimo

SET radical version 4.2 was attached to the left index finger.

Time from power on to acquire the pulse wave and oxygen

saturation (SpO2), time from the application of air tourniquet

with 250 mmHg on the upper arm to loss of pulse wave and

SpO2, and time from the release of the tourniquet to acquire

the pulse wave and SpO2were measured. Then, the patients

left hand and arm were cooled gradually to 27C dermal tem-

perature in a room at 19C. The temperatures at loss of the

pulse wave and SpO2were recorded.

Results: The Nellcor N-595 was the slowest to detect SpO2

and pulse wave at power on. The Masimo SET showed pulse

wave and SpO2longer than the other two monitors after tour-niquet on. The Nellcor N-595 was the fastest to show pulse

wave and SpO2following tourniquet release.

Conclusion:The Masimo SET was the slowest to respond to

the changes in perfusion, and the Nellcor N-595 responded the

fastest. However, the Nellcor N-595 was the slowest to show

SpO2and pulse wave at power on.

Objectif: De nouveaux sphygmo-oxymtres qui utilisent des

algorithmes rcents sont vendus comme insensibles au mouvement

et lhypoperfusion. Nous avons compar la performance de trois

sphygmo-oxymtres dans des conditions dhypothermie et de perfu-

sion modifie.

Mthode: Dix volontaires masculins ont accept de participer

ltude approuve par linstitution. La sonde du Dolphin 2100, duNellcor N-595 ou du Masimo SET de version radicale 4,2 a t

fixe lindex gauche. Le temps coul depuis la mise en marche

jusqu lacquisition de londe pulse et de la saturation en oxygne

(SpO2), depuis lapplication du garrot sur le bras avec une pression

de 250 mmHg jusqu la perte de londe pulse et de la SpO2et,

enfin, depuis le retrait du garrot jusqu lacquisition de londe pul-

se et de la SpO2ont t mesurs. Puis, la main et le bras gauches

ont t refroidis graduellement jusqu une temprature cutane

de 27 oC dans une pice chauffe 19 oC. La temprature a t

note au moment de la perte de londe pulse et de la SpO2.

Rsultats: Le Nellcor N-595 a t le plus lent dtecter la SpO2

et londe pulse au moment de la mise en marche. Aprs la pose

du garrot, le Masimo SET a t plus lent que les deux autresmoniteurs montrer londe pulse et la SpO

2. Le Nellcor N-595

a t le plus rapide afficher londe pulse et la SpO2 aprs le

relchement du garrot.

Conclusion : Le Masimo SET a t le plus lent rpondre aux

changements de perfusion et le Nellcor N-595 le plus rapide. Par

contre, le Nellcor N-595 a t le plus lent montrer la SpO2

et

londe pulse au moment de la mise en marche.

136 GENERALANESTHESIA

CAN J ANESTH 2006 / 53: 2 / pp 136138

Pulse oximeters demonstrate different responsesduring hypothermia and changes in perfusion

[Les sphygmo-oxymtres affichent des rponses diffrentes pendant lhypothermie etles changements de perfusion]

Tomoki Nishiyama MDPhD

From the Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.Address correspondence to:Dr. Tomoki Nishiyama, 3-2-6-603, Kawaguchi, Kawaguchi-shi, Saitama, 332-0015, Japan. Phone: 81-3-5800-8668;

Fax: 81-3-5800-9655; E-mail: [email protected] external funding samples were used in support of this study.

Assessed April 11, 2005.Revision accepted for publication August 23, 2005.Final revision accepted September 8, 2005.
http://%20mailto:[email protected]/http://%20mailto:[email protected]/


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The Masimo SET might be more resistant thanother monitors to the altered perfusion induced by atourniquet. However, the Nellcor N-595 respondedfaster than the others when perfusion returned, and theMasimo SET was the slowest to recover. Application oftourniquet pressure at 250 mmHg might induce com-plete occlusion of blood flow rather than hypoperfu-sion in patients with normal blood pressure. Therefore,it might be possible that the response to loss of bloodflow and to reflow was the slowest in the Masimo SET,

which enabled the Masimo SET to show the pulsewave and SpO

2 longer than the other monitors, even

when blood flow was occluded. This does not implythat the Masimo SET could detect the pulse wave andSpO2better than the other two systems at a reducedstate of perfusion. Different blood pressures mightinfluence the effects of the tourniquet. Althoughblood pressure was not measured in the present study,

volunteers were young without hypertension, and eachdevice was repeated for each subject. Therefore, theeffects of blood pressure should be small.

Cooling the hand to 27C, which was the lowerlimit in awake volunteers, had no effect on detect-ing pulse wave and SpO2 in each monitor tested.However, it was unclear how the perfusion decreasedat 27C, though fingers were cyanosed. Methodsusing a tourniquet or cooling might be differentfrom clinical situations with hypoperfusion, such ashypovolemia, deep anesthesia or shock secondary tosepsis etc., because humoral or neural responses mightalso bear an influence in such clinical situations.

There are several studies comparing the Masimo SETwith conventional pulse oximeters. Using the coolingenvironment and tapping and rubbing motions, theMasimo SET performed significantly better duringmotion and hypoperfusion than the other pulse oxim-eters (Nellcor N-395, Tyco Healthcare, Pleasanton,CA, USA; Datex-Ohmeda AS/3, Datex-Ohmeda,Madison, WI, USA; Marquette 8000, GE HealthcareIT, Milwaukee, WI, USA).4In a study comparing theMasimo SET, Nellcor N-395, N-20PA, and D-25, timeto loss of signal during blood pressure measurement bycuff was longer in the Masimo SET.3 The MasimoSET and the Nellcor N-395 showed shorter times to

recover than the other monitor types.3These studiessuggest that the Masimo SET could offer advantagesover conventional pulse oximeters. However, therehave been no studies comparing the Masimo SET withother pulse oximeters using the new technologies.

Conventional pulse oximetry derives SpO2from theratios of emitted vstransmitted light (Lambert-Beerslaw), whereas the Masimo SET utilizes a patenteddiscrete saturation transform algorithm to process the

SpO2.2The Masimo SET calculates SpO2without first

referencing the pulse rate, whereas recognition of astable pulse is prerequisite to conventional oximeters.Therefore, response time was faster with the MasimoSET than the conventional oximeters. The MasimoSET pulse rate and SpO

2

algorithms are so robust thatthey capture more true bradycardiac and hypoxemicevents than conventional pulse oximeters during bothmotion and hypoperfusion.5The Nellcor N-595 has adigital tip in the sensor (OxiMaxTM, Tyco Healthcare,Pleasanton, CA, USA).6Each sensor of the OxiMaxTMcontains all the calibration and operating characteris-tics for that individual sensor. It allows an informa-tion exchange between the sensor and the monitor,improving monitoring performance.6 Therefore, theNellcor N-595 had a faster response than the MasimoSET. The Dolphin 2100 uses oximetry noise elimina-tion (ONETM, Dolphin Medical, Hawthorne, CA,

USA) technology, in which light signals are digitalizedin the sensor. The different responses at hypoper-fusion or occlusion of blood flow of these threemonitors could not be related to the differences intechnologies, due to lack of basic studies and detailsfrom the manufacturers. To better discriminate theclinical differences of these pulse oximeters, furtherstudies using quantitative motion, hypoperfusion, anddeeper cooling should be performed.

In conclusion, for the monitors tested, the MasimoSET was the slowest to respond to changes of perfu-sion, and the Nellcor N-595 responded the fastest.The Nellcor N-595 was the slowest to show SpO2and

pulse wave at power on.

References

1 Barker SJ. Motion-resistant pulse oximetry: a com-

parison of new and old models. Anesth Analg 2002;

95: 96772.

2 Dumas C, Wahr JA, Tremper KK. Clinical evaluation

of a prototype motion artifact resistant pulse oximeter

in the recovery room. Anesth Analg 1996; 83: 26972.

3 Kawagishi T, Kanaya N, Nakayama M, Kurosawa S,

Namiki A. A comparison of the failure times of pulse

oximeters during blood pressure cuff-induced hypoper-

fusion in volunteers. Anesth Analg 2004; 99: 7936.

4 Barker SJ. Standardization of the testing of pulse oxim-eter performance. Anesth Analg 2002; 94(1 Suppl):

S1720.

5 Goldstein MR. Left heart hypoplasia. A life saved with

the use of a new pulse oximeter technology. Neonatal

Intensive Care 1998; 12: 147.

6 Mannheimer PD, Bebout DE. The OxiMax System.

Nellcors new platform for pulse oximetry. Minerva

Anestesiol 2002; 68: 2369.


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