Effect of nail polish on oxygen saturation determined by pulse oximetry in
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Resuscitation (2007) 72, 82—91 CLINICAL PAPER Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients夽 Jochen Hinkelbein ∗, Harald V. Genzwuerker, Reiner Sogl, Fritz Fiedler University Clinic for Anesthesiology and Intensive Care Medicine, Faculty of Clinical Medicine Mannheim, Ruprecht-Karls-University Heidelberg, University Hospital Mannheim, Theodor-Kutzer-Ufer 1-3, D-68167 Mannheim, Germany Received 16 February 2006 ; received in revised form 30 May 2006; accepted 13 June 2006 KEYWORDS Summary Nail polish; Introduction: Nail polish of different colours may alter accuracy and precision of Pulse oximetry; pulse oximetry as previous data in healthy volunteers suggest. This trial evaluates Monitoring; the oxygen saturation determined by pulse oximetry and haematoximetry with nail Hematoximetry; polish of nine different colours applied. Bias; Material and methods: Fifty critically ill and mechanically ventilated patients in an ICU were investigated in a prospective clinical—experimental trial. On nine ﬁnger Functional oxygen nails polish of different colours was applied in a predetermined consecutive order. saturation; Functional oxygen saturation was determined by pulse oximetry (SpO2 ) on each ﬁnger Intensive Care Medicine; for each colour with the ﬁnger sensor probe both in the normal position and at a SaO2 ; 90◦ rotation. Simultaneously oxygen saturation was determined by haematoximetry SpO2 (SaO2 ). Accuracy (bias, S = SaO2 −SpO2 ) and precision (standard deviation, S.D.) of pulse oximetry were analyzed with the t-test. A value of P < 0.05 was considered signiﬁcant. Results: While black (S = +1.6 ± 3.0%), purple (S = +1.2 ± 2.6%) and dark blue nail polish (S = +1.1 ± 3.5%, each N = 50) had the greatest effect (P < 0.05), all other colours, including colourless nail polish, had a smaller effect (mean bias +0.2 to +0.9%). A rotation of 90◦ reduced the bias from +2.8 to +1.3% (N = 10, n.s.). Conclusion: Nail polish does not alter pulse oximetry readings in mechanically ven- tilated patients to a clinically relevant extent. The mean error of measurement for all colours was within the manufacturers’ speciﬁed range of ±2%. A 90◦ rotation of the sensor probe does not eliminate errors in measurement. To remove nail polish might be helpful to decrease the error of measurement in some cases. © 2006 Elsevier Ireland Ltd. All rights reserved. 夽 A Spanish translated version of the summary of this article appears as Appendix in the ﬁnal online version at 10.1016/j.resuscitation.2006.06.024. ∗ Corresponding author. Tel.: +49 621 383 2415; fax: +49 621 383 732740. E-mail address: firstname.lastname@example.org (J. Hinkelbein). 0300-9572/$ — see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.resuscitation.2006.06.024
Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients 83 Introduction patients. Only a few studies, all performed with a small number of volunteers, have substantiated Since improvements to the pulse oximeter in the these results. Studies involving mechanically venti- early 1970s by Takuo Aoyagi from the Nihon Kohden lated and critically ill patients, have not been pub- Corporation, pulse oximetry has become a stan- lished to date. Furthermore, newer and improved dard monitoring technique during anaesthesia in pulse oximeters and sensors and new nail polish the operating room (OR), treatment in the ICU products require further evaluation and an accu- and emergency medical resuscitation of critically racy validation of the bias induced by nail polish. ill patients.1,6,9,21,28,33 Pulse oximeters determine A prospective experimental clinical trial in the percentage of oxygenated haemoglobin within mechanically ventilated critically ill patients in an pulsatile arterial blood, which is known as func- intensive care unit was performed using haema- tional (or partial) oxygen saturation. By means of toximetry and pulse oximetry to evaluate the mea- haematoximetry — widely considered a reference — surements using the two techniques with different the functional oxygen saturation may also be deter- nail polish colours. mined. During patient monitoring using pulse oximeters the early detection of untoward events is most Material and methods important, as it may contribute to the prevention of hypoxic insults,6 and therefore improve patient Patients safety.9,21 Since the deleterious effects of peri- operative hypoxaemia has been recognised, the use This study was approved by the local ethics com- of pulse oximetry has become standard in operating mittee for human research and was performed in rooms.33 accordance with the ethical standards laid down It must be noted however, that circumstances in the 1964 Declaration of Helsinki. Relatives were exist in which the pulse oximeter may give inac- informed about the procedure and asked for writ- curate or misleading information about arterial ten informed consent prior to inclusion in the oxygen saturation. Until now, many factors have study. been described which can lead to erroneous results Data were collected on all patients of the ICU in measurement of oxygen saturation by pulse meeting inclusion within 1 year. The inclusion cri- oximetry. One of these factors is the use of nail teria were an age of at least 18 years, white skin polish.8,12,13,27,34 Blue, green, and black coloured colour (Caucasian race), and mechanical ventila- nail polish are considered especially to result in tion for at least 24 h via a tracheal tube. All patients inaccurate measurements. had been admitted to the ICU at least 24 h before Today the effect of nail polish on pulse oximetry inclusion. Five ﬁngers on each upper extremity is discussed extensively but has not been inves- without nail polish applied prior to the trial were tigated in critically ill or mechanically ventilated essential to participate. Carboxyhaemoglobin and Figure 1 Absorption spectra of all colours used: (1) black, (2) dark green, (3) purple, (4) dark blue.
84 J. Hinkelbein et al. Figure 2 Absorption spectra of all colours used: (5) red, (6) light blue, (7) colourless, (8) light green, (9) yellow. methaemoglobin values each had to be less than and module SIREM, Siemens Medical Electronics, 4.0% when determined by haematoximetry. Danvers/USA) connected to a re-usable ﬁnger sen- If the plethysmographic waveform was of poor sor probe NELLCORTM DS-100A Durasensor® (Nell- quality (by visual analysis of a ﬂat or irregu- cor Puritan Bennett Inc., Pleasanton, USA). This lar signal waveform or difference to ECG heart sensor probe contains two different light emit- rate of more than 3 beats per minute), the ting diodes (LED), emitting light at wavelengths patient was excluded. If there was a nail myco- of 660 and 920 nm, and a photo detector diode sis, severe anaemia (Hb < 6.0 g/dl), severe hypoten- (PDD) that measures light passing through the sion (systolic blood pressure 40 mg/dl), To facilitate assignment of colours, the ﬁngers or hypothermia (temperature < 34 ◦ C), the patient were numbered consecutively from left to right was also excluded because interference had been (thumb of left hand = no. 1, second ﬁnger of the left reported previously for these factors when using hand = no. 2, middle ﬁnger of the left hand = no. 3, pulse oximetry.18,23,24,28,31,32 and thumb of right hand = no. 6, etc.). On 9 of 10 ﬁn- gers, nail polish of a different colour was applied in Nail polish two coats by the same investigator. Order of appli- cation was standardised to ensure that among the Due to the great number of nail polish brands patients, each ﬁnger was studied at least once with and types available, it was impractical to test all each colour: variations in colour and pigment composition. We Subject #1: ﬁnger 1 = colour 1; ﬁnger 2 = colour selected nine different colours of nail polish over 2; ﬁnger 3 = colour 3; and so on. No nail polish was the full colour spectrum: black, dark blue, light applied on ﬁnger 10. For subject #2, the colours blue, dark green, light green, yellow, red, pur- and ﬁngers were changed: ﬁnger 1 = colour 2; ﬁnger ple, and colourless (Table 1) available internation- 2 = colour 3; ﬁnger 3 = colour 4; and so on. No nail ally. The spectral analysis for each colour (maxi- polish was applied on ﬁnger 9, and ﬁnger 10 = colour mum peak and minimum absorption wavelength) 1. This rotation sequence was applied for all further was performed three times with a spectrophotome- patients. ter (LS 500, DRLANGE, Germany) between 500 and Each coat was allowed to dry completely 950 nm (Figures 1 and 2) analysing standardised two for 2 min between the applications (completely layers of nail polish. None of the suppliers of nail dry and not sticky; tested by the investigator). polish were involved in this study. After the second coat was completely dried, the measurements were taken. The remaining Measurement ﬁnger without nail polish served as a control for the SpO2 of the ﬁngers with nail polish All readings with pulse oximetry were obtained applied and additionally for the SaO2 obtained by with a SIEMENS pulse oximeter (monitor SC1281 haematoximetry.
Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients Table 1 Characteristics of different colours used Colour Black Dark blue Light blue Dark green Light green Yellow Red Purple Colourless None Name Diamant Diamant FABIANI no. 2 Super Quick Dry FABIANI no. 3 KRON 79 MISSLYN no. 34 FABIANI no. 5 CHICOGO 581 n.a. Sensation 975 Sensation 550 no. 85 Clear Manufacturer COTY ASTOR, COTY ASTOR, Dobner Kosmetik, Lady Manhattan Dobner Kosmetik, INTERCO, INTERCO, Dobner Kosmetik, Rimmel, London, n.a. Barcelona, Spain Barcelona, Spain Albaching, Cosmetics GmbH, Albaching, Wiesbaden, Wiesbaden, Albaching, UK Germany Stuttgart, Germany Germany Germany Germany Germany Wavelength (peak max, 830 690 710 720 500 640 550 530 890 n.a. nm) Wavelength min (nm) 520 500 950 510 950 500 950 950 500 n.a. SpO2 ± S.D. (%) 96.2 ± 3.2 96.6 ± 3.6 96.8 ± 2.7 96.9 ± 2.5 97.2 ± 2.7 97.0 ± 2.4 96.9 ± 2.4 96.6 ± 2.9 97.1 ± 2.5 97.5 ± 2.2 Bias ± S.D. (%) 1.6 ± 3.0 1.1 ± 3.5 0.9 ± 2.2 0.9 ± 2.3 0.6 ± 2.3 0.8 ± 2.1 0.8 ± 2.0 1.2 ± 2.6 0.7 ± 2.2 0.2 ± 1.5 Bias maximum 10.6% 9.1% 8.5% 9.1% 9.5% 6.5% 5.4% 12.5% 7.5% 4.1% Bias minimum −4.1% −5.7% −2.9% −4.4% −5.1% −3.1% −2.9% −3.1% −5.1% −2.9% Bias in the deﬁned 26 (52%) 23 (46%) 31 (62%) 34 (68%) 39 (78%) 36 (72%) 36 (72%) 34 (68%) 35 (70%) 42 (84%) interval, S < ±2% Bias, S > +2% (n)/% 19 (38%) 18 (36%) 15 (30%) 13 (26%) 9 (18%) 12 (24%) 12 (24%) 14 (28%) 12 (24%) 6 (12%) Bias, S < −2% (n)/% 2 (4%) 7 (14%) 3 (6%) 2 (4%) 2 (4%) 1 (2%) 2 (4%) 1 (2%) 3 (6%) 2 (4%) Limits of agreement: 1.6 ± 6.0 1.1 ± 7.2 0.9 ± 4.4 0.9 ± 4.6 0.6 ± 4.6 0.8 ± 4.2 0.8 ± 4.0 1.2 ± 5.2 0.7 ± 4.4 0.2 ± 3.0 S ± 2S.D. (%) Limits of agreement (%) −4.4 to +7.6 −6.1 to +8.3 −3.5 to +5.3 −3.7 to +5.5 −4.0 to +5.2 −3.4 to +5.0 −3.2 to +4.8 −4.0 to +6.4 −3.7 to +5.1 −2.8 to 3.2 Limits of agreement: 12.0 14.4 8.8 9.2 9.2 8.4 8.0 10.4 8.8 6.0 dimension (%) Total number (n) 50 (100%) 50 (100%) 50 (100%) 50 (100%) 50 (100%) 50 (100%) 50 (100%) 50 (100%) 50 (100%) 50 (100%) Signiﬁcance of SpO2 to P < 0.002 P < 0.04 P < 0.008 P < 0.02 n.s. P < 0.02 P < 0.006 P < 0.004 P < 0.04 n.s. SaO2 85
86 J. Hinkelbein et al. The ﬁnger sensor probe was applied directly to of measurement error were calculated.3,29 As an the center of the ﬁngernail on each foreﬁnger to indicator for the spread of readings, the difference ensure that light passed the ﬁnger from dorsal to between the minimum bias and the maximum bias volar side (standard position, top-to-bottom posi- was calculated for each colour. A value of P < 0.05 tion). When stable pulse oximeter readings of oxy- was considered signiﬁcant. gen saturation were obtained for at least 20 s, the Statistical analysis was performed with reading was recorded. STATISTIKA® (V 6.0, StatSoft Inc., USA). The In 10 randomly selected patients, the probe was T-test for paired values was used to analyze the additionally rotated by 90◦ , so that the optical path signiﬁcance of variables. Values are expressed as cut laterally through the ﬁnger and not through the means ± standard deviation (range). nail bed (side-to-side position). When a stable mea- surement of oxygen saturation was reached for at least 20 s another reading in the lateral position was Results recorded. At the same time as the pulse oximetry mea- Patient characteristics surement, an arterial blood sample for analysis was drawn by a second person. The time-point was stan- A total of 50 critically ill patients with ventilation dardised and scheduled between the pulse oxime- support (19 female and 31 male) in our ICU were try measurement at ﬁnger no. 5 and ﬁnger no. 6. included in this clinical study, representing 500 data The blood samples were obtained in all patients points (i.e. 10 ﬁngers and readings each) between via an arterial catheter already in place as part August 1st and December 31st , 2003. A total of 212 of the routine clinical management in the right patients had to be excluded because they were or left radial artery and functional arterial oxy- not mechanically ventilated (N = 184), presented gen saturation (SaO2 ) was determined optically by a no sufﬁcient plethysmographic pulse wave signal haematoximeter (Radiometer Copenhagen ABL Sys- (N = 16), relatives declined to participate (N = 6), tem 625, Radiometer, Brønshøj, Denmark). For fur- were younger than 18 years (N = 4) or were not ther analysis, the functional oxygen saturation of of Caucasian race (N = 2). No patient had to be both techniques was compared. excluded due to dyshaemoglobinemia, nail myco- sis or amputation of ﬁngers. Statistical data analysis All participating patients suffered from surgical diseases and surgical interventions as the reasons The functional oxygen saturation (SaO2 ) is deﬁned for admission to the ICU (Table 2). The mean as the concentration of oxyhaemoglobin divided by fraction of inspired oxygen (FiO2 ) was 49 ± 15% the total present haemoglobin able to carry oxygen: (range, 21—100%) resulting in a mean arterial SaO2 = oxyhaemoglobin [O2 Hb]/(oxyhaemoglobin partial oxygen pressure of 104.6 ± 29.2 mmHg [O2 Hb] plus desoxyhaemoglobin [dHb]).22 SaO2 is (range, 73.1—213.1 mmHg) and a measured usually used as a reference for functional oxygen mean oxygen saturation SaO2 of 97.8 ± 1.3% saturation determined by pulse oximetry (SpO2 ). (range, 94.3—100.0%). The mean temperature was Statistical analysis of the data focused on the dif- 37.1 ± 0.4 ◦ C (range, 36.4—38.1 ◦ C, N = 50), the ference in oxygen saturation between the ﬁngers to signal quality of pulse oximetry readings was not which nail polish had been applied, and the corre- impaired by severe hypothermia. sponding ﬁnger without nail polish in the subject, and the oxygen saturation determined by haema- Analysis of accuracy toximetry. To assess the congruence of measurement All colours of nail polish showed a different impair- between the two techniques, different analytical ment of the readings of pulse oximetry. Mean SaO2 methods were used: the method described by Bland (97.8 ± 1.3%, range 94.3—100.0%, N = 50) correlated and Altman3 was used to calculate the mean differ- well with the mean SpO2 of the unpainted ﬁnger ence between SaO2 and SpO2 and hence measure- (S = +0.2 ± 1.5% [range, −2.9 to +4.1%], N = 50, ment accuracy (accuracy, bias, S = SaO2 − SpO2 ). n.s.). To assess the precision of measurements, stan- While black (S = +1.6 ± 3.0% [range, −4.1 dard deviation of the differences (S.D., variability) to +10.6%], P < 0.002), purple (S = +1.2 ± 2.6% between SpO2 and SaO2 , the number of outliers [range, −3.1 to +12.5%], P < 0.004) and dark blue (bias-values above and below the manufacturers’ nail polish (S = +1.1 ± 3.5% [range, −5.7 to +9.1%], given interval of ±2%), and the limits of agree- P < 0.04) revealed the greatest effect, all other ment (bias ± 2S.D.) in all used colours as an index colours reached a mean bias below 1% (Table 1).
Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients 87 Table 2 Demographical and epidemiological data of all participating patients Number (N) (%) Sex Male (N) 31 (62%) Female (N) 19 (38%) Diagnosis Subarachnoid hemorrhage (N) 12 (24%) Trauma (N) 7 (14%) Carcinoma (N) 5 (10%) ARDS (N) 4 (8%) Shock (N) 4 (8%) Sepsis (N) 2 (4%) Other (N) 16 (32%) Ventilation Intubation/tracheostomy and mechanical ventilation (N) 50 (100%) Demographic Age (years) 59 ± 14.2 (20—82) Ventilation FiO2 (%) 49.4 ± 15.3 (21.0—100.0) Circulation Systolic blood pressure (mmHg) 138 ± 27 (86—199) Temperature (◦ C) 37.1 ± 0.4 (36.4—38.1) Haematoximetry and arterial blood gases Oxygen saturation (SaO2 ) (%) 97.8 ± 1.3 (94.3—100.0) paO2 (mmHg) 104.6 ± 29.2 (73.1—213.1) paCO2 (mmHg) 43.9 ± 6.9 (29.9—60.0) pH 7.438 ± 0.067 (7.259—7.624) COHb (%) 1.6 ± 0.6 (0.4—3.1) MetHb (%) 0.8 ± 0.3 (0.2—1.8) Haemoglobin (g/dl) 9.0 ± 1.5 (6.4—12.0) Plasma bilirubin (mg/dl) 1.96 ± 3.85 (0.17—19.88) Subgroups Patients with parenteral nutrition (lipids) (ml/h), N = 20 70 ± 18 (42—110) Patients with Noradrenaline (nor epinephrine) (g/kg/min), N = 17 22.4 ± 29.3 (1.3—100.0) Data are given as number (N) and percentage (%) or as mean ± standard deviation (S.D.) and range. Light green nail polish (S = +0.6 ± 2.3% [range, There was a wide range for the spread of each −5.1 to +9.5%], n.s.) had the smallest effect of of the colours’ bias values (minimum bias to maxi- all colours used. With the exception of light green mum bias of each reading) with a maximum of 15.6% and the unpainted nail, a statistically signiﬁcant (range, −3.1 to +12.5%) with the colour purple. The difference to the SaO2 was found for all colours minimum range of bias values (8.3%) was achieved (Figure 3). with red nail polish (range, −2.9 to +5.4%). The mean bias was always inside the speciﬁed limit of ±2% and was positive (S > 0%) for all mea- surements implicating that pulse oximetry usually Analysis of outliers underestimates the actual oxygen saturation deter- Concerning the outliers (i.e. the number of bias val- mined by haematoximetry (SaO2 > SpO2 ). ues over and below the speciﬁed manufacturers’ range of ±2%20 ), the results of our study show that Analysis of precision SpO2 usually tends to underestimate SaO2 in criti- cally ill ventilated patients with nail polish applied. The standard deviation of functional oxygen satu- Of all readings, a total of N = 130 readings (i.e. ration in each colour ranged from 2.0% (red nail 26 ± 7.7% [range, 12—38%] from N = 500) had a bias polish) to 3.5% (dark blue nail polish). The standard greater than the speciﬁed +2% with a SpO2 lower deviation at the unpainted ﬁnger was lowest (1.5%). than SaO2 . In contrast, only N = 25 readings (i.e.
88 J. Hinkelbein et al. Figure 3 Mean bias depending on the colour of nail polish. The whiskers show maximum and minimum bias, the thick black horizontal line the mean bias. Top and bottom of the box describe the 25 and 75% quartiles. 5 ± 3.4% [range, 2—14%] from N = 500) had a bias Discussion below −2% (SpO2 higher than SaO2 ). With black nail polish, the bias was greater than Takuo Aoyagi was the ﬁrst engineer to develop an +2% in N = 19 (38%) measurements while with dark apparatus and sensor able to perform real-time blue there were N = 18 (36%) measurements out- pulse oximetry for routine clinical use.1,28 Today side the manufacturers interval. The fewest out- pulse oximetry has become a standard monitoring liers >+2% were found (N = 6, 12%) if no nail polish technique during anaesthesia, intensive care ther- was applied. apy and emergency medical treatment. Many factors which can affect values of oxygen Analysis of the limits of agreement saturation obtained by pulse oximetry have been previously described: extreme anaemia,15,16,18,31 The dimension of the limits of agreement was cal- pharmacotherapy with catecholamines,15,31 culated as the bias ± 2S.D. The limits of agreement carboxyhaemoglobinaemia and elevated COHb- range between 6.0% for the unpainted ﬁngernail levels,2,4,19,23 dried blood at sensor site,26 indicating a small variation of all readings, and hyperbilirubinaemia,23,32 hypotension and 14.4% for the dark blue colour nail polish, indicating hypoperfusion,11,15,31 hypoxia,28,30 intravenous a great variation of the differences. dyes,23 motion23 and methaemoglobinaemia and elevated MetHb level.10,23 Additionally, the sensor Analysis of reliability and variability after site inﬂuences measurement due to variable kinet- 90◦ rotation ics, although the effect is small and may be not clinically relevant.7,14,25 In the 10 patients randomly selected for evalua- Nail polish has been reported to interfere tion of a 90◦ rotation of the ﬁnger sensor probe with pulse oximetry.5,8,27,34 There is ongoing (ﬁve male, ﬁve female, mean age 64 ± 12 [range, controversy,17 especially since all studies per- 42—76] years) a mean SaO2 of 97.7 ± 1.1% [range, formed to date only involved healthy volunteers but 95.6—99.3%] was measured. In 40 out of a total did not include critically ill patients on ventilatory of 100 values, the calculated bias was above +2% support. or below −2%. These data sets were chosen for Theoretically, there should be no inﬂuence further investigation. In these data pairs, the bias of nail polish on pulse oximetry, because pulse was calculated as S = +2.8 ± 3.7% [range, −2.8 to oximetry uses the pulsatile light-absorption of +9.5%] (N = 40), and after rotation of the ﬁnger sen- haemoglobin to determine oxygen saturation. How- sor probe by 90◦ as S = +1.3 ± 2.2% [−1.4 to +4.6%] ever, our results show that there is an interference (N = 40, P > 0.05). that is most signiﬁcant for black, purple and dark
Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients 89 Figure 4 Overall relationship between SaO2 (x-axis) and SpO2 (y-axis) at the unpainted ﬁnger. blue nail polish. All other colours, and colourless sibly black and brown-red nail polishes interfere nail polish, had a lesser effect on pulse oximetry with pulse oximetry. These colours reduced the readings. SpO2 reading up to 6% with an underestimation of In all colours tested, pulse oximetry (SpO2 ) SaO2 . This effect was clinically relevant and was tended to underestimate the oxygen saturation attributed to the fact that these colours had higher determined by haematoximetry (SaO2 ). Readings absorbance near 660 nm causing the oximeter to obtained by pulse oximetry were generally lower artiﬁcially detect a higher proportion of desoxy- compared to SaO2 readings if nail polish is applied, haemoglobin. The authors concluded that removal while values correlated well when no nail polish is of nail polish is mandatory before a pulse oximeter applied (Figure 4). A possible explanation for the sensor is attached to prevent erroneous oximeter slight decrease in oxygen saturation readings with readings.8 nail polish present could be a decrease of pulse Brand et al.5 also tested healthy subjects. Ten wave signal quality due to an increased absorption different colours of nail polish with three coats of light. were applied on the three inner ﬁngers. The index Most manufacturers (e.g. SIEMENS for the SC1281 ﬁnger of the opposite side was used for control mea- used in this study) specify that their pulse oxime- surements. In contrast to Coté et al.,8 Brand et al.5 ter readings are reliable with a deviation of ±2% in found impairment of not more than 1% in green and the saturation range from 70 to 100%.20 Even with blue nail polish. black, purple and dark blue nail polish applied on Important limitations of all the studies described the ﬁngernails of critically ill patients, the devia- are the lack of patient data and the small number tion or mean bias was within the speciﬁed range of of subjects studied. There is no study published to ±2%. Average measurements were always within a date investigating the inﬂuence of nail polish on clinically acceptable range. pulse oximetry readings in critically ill patients. In First reports on the inﬂuence of nail polish on addition, no study is available which includes crit- pulse oximetry can be found in letters from the mid ically ill patients on ventilation support and eval- to late 1980s17,27 and the results described were uates the error in measurement with nail polish in controversial. Kataria and Lapkins found no signiﬁ- this patient group. cant error in the measurement in 15 volunteers with In mechanically ventilated and critically ill nail polish applied, and therefore stated that nail patients with multiple factors inﬂuencing pulse polish does not affect pulse oximeter saturation.17 oximetry, accurate readings are essential. In this Rubin et al. described effects of nail polish of population a lower accuracy and lower precision of 31 different colours on oxygen saturation deter- the measurement (i.e. due to application of cate- mined by pulse oximetry. However, one female cholamines, haemodynamic changes, etc.) is possi- volunteer was the sole subject of this study.27 ble. Since the available data obtained in healthy Both studies did not quantify the degree of the volunteers may not be applicable to critically ill impairment. and mechanically ventilated patients, we evaluated Coté et al.8 investigated 14 male and female the accuracy and precision of pulse oximetry in this volunteers and reported that blue, green and pos- patient population.
90 J. Hinkelbein et al. The comparison of measurements of pulse Conclusion oximetry with the oxygen saturation determined by haematoximetry in ﬁngers with nail polish has also The nine colours of nail polish tested did not inter- not been described so far. fere with pulse oximetry to a clinically relevant Our trial identiﬁed black, purple, and dark blue extent. The mean error of measurement for all as the most inﬂuencial colours. Coté et al.8 found colours was within the manufacturers’ speciﬁed black and blue to have a signiﬁcant inﬂuence as range of ±2%. The actual oxygen saturation tends well. Blue was also identiﬁed by Brand et al.5 In to be underestimated if nail polish is applied com- addition, both authors reported green to lead to a pared to SaO2 measurements. signiﬁcant bias. In this trial we found dark green Clinically signiﬁcant deviations in pulse oximeter (not light green) to inﬂuence the measurement sig- readings rarely seem to be caused by nail polish. To niﬁcantly, but with a smaller bias than black, purple remove nail polish might be helpful to decrease the and dark blue. error of measurement in some cases. While Brand et al.5 reported the bias to be below 1%, Coté et al.8 found the bias to be up to 6%. Consequently, our results from critically ill Acknowledgements patients are largely in accordance with Coté et al.8 However, in contrast to Coté et al.8 we cannot No ﬁnancial or material support was received for recommend that nail polish generally is removed, this study from the companies mentioned. We wish because the mean bias is below 2% compared to to thank the patients and staff of our ICU as well as haematoximetry, although there were some severe the members of the Institute of Clinical Chemistry outliers with a great bias. at the University Hospital Mannheim who performed the photo spectral analysis of the nail polishes, for Elimination of faulty results their support. Preliminary results were presented at The Sec- To eliminate faulty pulse oximetry results in sub- ond Mediterranean Emergency Medicine Congress jects with nail polish applied, White et al.34 and 2003 at Sitges/Spain13 and at the Annual Meeting Brand et al.5 recommended rotating the sensor of the European Society of Anaesthesiologists 2004 probe by 90◦ . We found that a rotation of the ﬁn- in Lisboa,12 as both an abstract and oral presenta- ger sensor probe by 90◦ from the standard posi- tion. tion can reduce faulty readings, but the changes are without clinical and statistical signiﬁcance. In contrast to the results of other authors,5,34 our References results revealed no signiﬁcant change in reliability, variability and accuracy of pulse oximetry readings 1. Aoyagi T, Kishi M, Yamaguchi K, Watanabe S. Improvement after 90◦ rotation; the underlying reasons remained of an ear piece oximeter. In: Abstracts of the 13th annual unclear. meeting of the Japanese Society for Medical Electronics and Biological Engineering. 1974. p. 90—1. 2. Barker SJ, Tremper KK. The effect of carbon monoxide Limitations inhalation on pulse oximetry and transcutaneous PO2 . Anes- thesiology 1987;66:677—9. We tested nine different colours of nail polish in 3. Bland JM, Altman DG. Statistical methods for assessing 50 critically ill ventilated patients. Different man- agreement between two methods of clinical measurement. ufacturers are assumed to use different chemical Lancet 1986;I:307—9. 4. Bozemann WP, Myers RAM, Barish RA. Conﬁrmation of the components. Although none of the nail polishes pulse oximetry gap in carbon monoxide poisoning. Ann Emerg tested had a clinically signiﬁcant effect on pulse Med 1997;30:608—11. oximetry readings, other nail polishes with differ- 5. Brand TM, Brand ME, Jay GD. Enamel nail polish does not ent chromatogenes may inﬂuence the accuracy of interfere with pulse oximetry among normoxic volunteers. J the pulse oximeter to a greater extent. If nail pol- Clin Monit Comput 2002;17:93—6. 6. Cheng EY, Hopwood MB, Kay J. Forehead pulse oximetry ish is not applied in the standardised two layers as compared with ﬁnger pulse oximetry and arterial blood gas in our study, the inﬂuence on the accuracy of pulse measurement. J Clin Monit 1988;4:223—6. oximetry may also vary. 7. Clayton DG, Webb RK, Ralston AC, Duthie D, Runciman WB. Unfortunately, we were only able to perform the A comparison of the performance of 20 pulse oximeters study in Caucasian patients with a SaO2 between under conditions of poor perfusion. Anaesthesia 1991;46: 3—10. 94.3 and 100%. Our ﬁndings may therefore be not 8. Coté CJ, Goldstein EA, Fuchsman WH, Hoaglin DC. The applicable to patients with a SaO2 outside this range effect of nail polish on pulse oximetry. Anesth Analg or non-Caucasian patients. 1988;67:683—6.
Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients 91 9. Eichhorn JH. Prevention of intraoperative anesthesia acci- randomized, controlled trials. Anesth Analg 2003;96: dents and related severe injury through safety monitoring. 426—31. Anesthesiology 1989;70:572—7. 22. Pologe JA. Functional saturation versus fractional sat- 10. Eisenkraft JB. Pulse oximeter desaturation due to methe- uration: what does pulse oximetry read? J Clin Monit moglobinemia. Anesthesiology 1988;68:279—82. 1989;5:298—9. 11. Hinkelbein J, Genzwuerker HV, Fiedler F. Detection of a sys- 23. Ralston AC, Webb RK, Runciman WB. Potential errors in pulse tolic pressure threshold for reliable readings in pulse oxime- oximetry III: effects of interference, dyes, dyshaemoglobins try. Resuscitation 2005;64:315—9. and other pigments. Anaesthesia 1991;46:291—5. 12. Hinkelbein J, Genzwuerker HV, Fiedler F. How nail polish 24. Ramsing T, Rosenberg J. Pulse oximetry in severe anaemia. alters oxygen saturation determined by pulse oximetry in Intens Care Med 1992;18:125—6. the ICU setting. Eur J Anaesthesiol 2004;21:42 (abstract). 25. Reynolds LM, Nicolson SC, Steven JM, Escobar A, McGonigle 13. Hinkelbein J, Genzwuerker HV, Fiedler F. Nail polish: bias ME, Jobes DR. Inﬂuence of sensor site location on pulse evaluation and accuracy validation for the measurement of oximetry kinetics in children. Anesth Analg 1993;76:751—4. oxygen saturation determined by pulse oximetry. J Emerg 26. Rosewarne FA, Reynolds KJ. Dried blood does not affect pulse Med 2004;26:377 (abstract). oximetry. Anaesthesia 1991;46:886—7. 14. Hinkelbein J, Hose D, Fiedler F. Comparison of three differ- 27. Rubin AS. Nail polish color can affect pulse oximeter satura- ent sensor sites for pulse oximetry in critically ill patients. tion. Anesthesiology 1988;68:825. Int J Intens Care 2005;12:159—63. 28. Severinghaus JW, Astrup PB. History of blood gas analysis. 15. Hinkelbein J, Osika A, Fiedler F. Accuracy and precision of Int Anesthesiol Clin 1987;25:1—224. pulse oximetry in ventilated patients of an intensive care 29. Severinghaus JW, Kellerher JF. Recent developments in pulse unit. Eur J Anaesthesiol 2004;21:179 (abstract). oximetry. Anesthesiology 1992;76:1018—38. 16. Jay GD, Huges L, Renzi FP. Pulse oximetry is accurate in acute 30. Severinghaus JW, Naifeh KH, Hoh SO. Errors in 14 pulse anemia from hemorrhage. Ann Emerg Med 1994;24:32—5. oximeters during profound hypoxia. J Clin Monit 1989;5: 17. Kataria BK, Lapkins R. Nail polish does not affect pulse 72—81. oximeter saturation. Anaesth Analg 1986;65:824. 31. Severinghaus JW, Spellman MJ. Pulse oximeter failure 18. Lee S, Tremper KK, Barker SJ. Effects of anemia on pulse thresholds in hypotension and vasoconstriction. Anesthesi- oximetry and continuous mixed venous haemoglobin satura- ology 1990;73:532—73. tion monitoring in dogs. Anesthesiology 1991;75:118—22. 32. Taylor MB, Whitwam JG. The current status of pulse oxime- 19. Lee WW, Mayberry K, Crapo R, Jensen RL. The accuracy of try. Anaesthesia 1986;41:943—9. pulse oximetry in the emergency department. Am J Emerg 33. van de Louw A, Cracco C, Cerf C, Harf A, Duvaldestin P, Med 2000;18:427—31. Lemaire F, et al. Accuracy of pulse oximetry in the inten- 20. Moyle JTB. Pulse oximetry. 2nd ed. London: BMJ Books; 2002. sive care unit. Intens Care Med 2001;27:1606—13. 21. Pedersen T, Moller AM, Pedersen BD. Pulse oxime- 34. White PF, Boyle WA. Nail polish and oximetry. Anesth Analg try for perioperative monitoring: systematic review of 1989;68:545—7.
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