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PubMed1997

[Role of nocturnal oximetry in screening for sleep apnea syndrome in pulmonary medicine. Study of 329 patients].

Nocturnal oximetry can show nocturnal oxygen desaturation. This examination was proposed as an investigation for the early detection of the sleep apnoea syndrome (SAS). We have compared the results of nocturnal oximetry and polysomnography in 329 consecutive patients seen in the department of thoracic medicine for the early detection of the SAS between June 1990 and June 1995. The diagnosis of SAS was confirmed at the time of polysomnography using an hypopnoea/apnoea index (IAH) greater or equal to 15 per hour. Two parameters of oximetry were well correlated with IAH less than 15 per hour: if the mean oxygen saturation is greater than 92% and for less than five per cent of the time of the examination there was a saturation of less than 90%. The sensitivity was 89.7% and the specificity was 57.8%. Among the 48 false positive cases on oximetry 17 patients were found to be suffering from COPD and 31 patients were probably suffering from a syndrome of upper airways resistance or possibly from the hypoventilation obesity syndrome. Amongst the 22 false, negatives to oximetry 10 non COPD patients with an IAH of greater than 30 per hour and diurnal somnolence had important anomalies of the oro-pharyngeal pathway as the origin of their nocturnal apnoea. The 12 other false negatives were patients with moderate SAS with an IAH of between 15 and 20 per hour. Logistical analysis has shown the association of the two oximetric criteria (mean oxygen saturation or percentage of time with a saturation of less than 5%) with clinical criteria (body mass index and formation on diurnal somnolence from a questionnaire) would enable a probable diagnosis of SAS in 75% of cases. Our study shows that nocturnal oximetry used an early diagnosis test, associated with clinical and respiratory function data enables the number of requests for polysomnography to be reduced.

Female↗
PubMed1996

[Usefulness of the visual analysis of night oximetry as a screening method in patients with suspected clinical obstructive sleep apnea syndrome].

Conventional polysomnography (CPS) is a complex, costly procedure that is not widely available, meaning that it is difficult to apply it in patients suspected of having obstructive sleep apnea syndrome (OSAS). Various procedures have therefore been proposed for screening candidates for CPS. We studied the usefulness of visual analysis of nocturnal oximetry in 96 patients suspected of having OSAS. The OSAS diagnosis was confirmed by CPS in 67 (69.8%). Oximetry was positive in 70 cases. Sixty-one patients were positive by both oximetry and CPS, while 9 and positive oximetry results and a negative CPS. We conclude that nocturnal oximetry has a 91% sensitivity and 69% specificity for OSAS, with a positive predictive value of 87% and a negative predictive value of 77%. We believe that nocturnal oximetry may be a useful way of screening for OSAS, in order to decrease the number of CPS performed on patients without the disease.

Adult↗
PubMed1989

Pulse oximetry in methemoglobinemia.

Pulse oximetry is a major improvement in the assessment of oxygenation. The device uses plethysmography and light absorbance measurements at two wavelengths to estimate oxygen saturation. It is inaccurate, however, when more than two types of hemoglobin are present. This article describes two infants with methemoglobinemia in whom pulse oximetry overestimated oxygen saturation. We discuss the mechanism of this systematic error and emphasize that pulse oximetry should not be used to estimate true oxygen saturation in the presence of methemoglobin. However, a disparity between oxygen saturation estimates by pulse oximetry and by calculations based on the arterial partial pressure of oxygen and the oxygen-hemoglobin dissociation curve can provide an important clue to the presence of such abnormal types of hemoglobins. Therapy should be based on direct measurements of oxyhemoglobin by cooximetry and not on measurements of oxygen saturation by pulse oximetry or on saturations calculated from the Pao2 and the oxyhemoglobin dissociation curve.

Carboxyhemoglobin↗
PubMed1996

Pulse oximetry: accuracy of methods of interpreting graphic summaries.

Although pulse oximetry has been used to determine the frequency and extent of hemoglobin desaturation during sleep, movement artifact can result in overestimation of desaturation unless valid desaturations can be identified accurately. Therefore, we determined the accuracy of pulmonologists' and technicians' interpretations of graphic displays of desaturation events, derived an objective method for interpreting such events, and validated the method on an independent data set. Eighty-seven randomly selected desaturation events were classified as valid (58) or artifactual (29) based on cardiorespiratory recordings (gold standard) that included pulse waveform and respiratory inductive plethysmography signals. Using oximetry recordings (test method), nine pediatric pulmonologists and three respiratory technicians ("readers") averaged 50 +/- 11% (SD) accuracy for event classification. A single variable, the pulse amplitude modulation range (PAMR) prior to desaturation, performed better in discriminating valid from artifactual events with 76% accuracy (P < 0.05). Following a seminar on oximetry and the use of the PAMR method, the readers' accuracy increased to 73 +/- 2%. In an independent set of 73 apparent desaturation events (74% valid, 26% artifactual), the PAMR method of assessing oximetry graphs yielded 82% accuracy; transcutaneous oxygen tension records confirmed a drop in oxygenation during 49 of 54 (89%) valid desaturation events. In conclusion, the most accurate method (91%) of assessing desaturation events requires recording of the pulse and respiratory waveforms. However, a practical, easy-to-use method of interpreting pulse oximetry recordings achieved 76-82% accuracy, which constitutes a significant improvement from previous subjective interpretations.

Adolescent↗
PubMed1993

Failure rate of pulse oximetry in the postanesthesia care unit.

OBJECTIVE: The objective of this study was to prospectively examine the incidence of patient-related failure of pulse oximetry in the postanesthesia care unit (PACU). METHODS: We studied 2,937 patients who, after receiving anesthesia, were admitted to the PACU at the University of Washington Medical Center from December 1989 through May 1990. Pulse oximetry readings were recorded using a Nellcor N-200 oximeter without electrocardiographic synchronization. Failure was defined as the inability to obtain a pulse oximetry reading for 2 or more 15-minute periods after eliminating probe position or mechanical malfunctions. RESULTS: The overall failure rate in our study was 0.64%, with 19 patient-related pulse oximetry failures from 2,937 cases. Patients on whom the device failed were significantly older (62 +/- 18 vs 46 +/- 19 yr [mean +/- SD]; p < 0.01), had higher median American Society of Anesthesiologists status (3 vs 2), and had longer operations than nonfailure patients (328 +/- 182 vs 185 +/- 127 min; p < 0.01). There was no difference in the duration of PACU times for both groups. CONCLUSIONS: The failure rate and patient characteristics compare favorably with a previously published study of intraoperative pulse oximetry failure. We conclude that while the pulse oximeter is a reliable instrument for the measurement of blood oxygenation, there is a small but consistent incidence of patient-related failure with this monitoring device in the PACU.

Age Factors↗
PubMed1985

Pulse oximetry in critically ill children.

To confirm the clinical applicability of a commercial pulse oximeter, we compared arterial hemoglobin saturation values determined by in-vitro oximetry and pulse oximetry in 15 critically ill children. One hundred ninety-two paired hemoglobin saturations were determined by both noninvasive pulse oximetry and direct measurement of arterial blood samples. The correlation between these two methods of measurement was statistically significant (r = 0.895; p less than 0.001). The mean percentage difference between the two measurements was 1.8%. Pulse oximetry was found to be safe and less cumbersome than other methods of monitoring arterial oxygen content. Overall, pulse oximetry was precise and provided a clinically satisfactory noninvasive method for continuously monitoring arterial hemoglobin saturation in critically ill children.

Child↗
PubMed1993

Experimental and predicted dual oximetry variability.

OBJECTIVE: We wished to determine whether the individual bias (mean difference) and precision (standard deviation of the difference) values of 2 variables, arterial oxygen saturation (SaO2) and mixed venous oxygen saturation (SvO2), could be used to predict the bias and precision values of the combined dual oximetry variable (SaO2-SvO2). METHODS: We simultaneously measured SaO2 by pulse oximetry and arterial blood gas co-oximetry and SvO2 by fiberoptic reflectance oximetry pulmonary artery catheter and venous blood gas co-oximetry in 238 data sets from 55 patients. Three different methods were used to predict the standard deviation of the difference of (SaO2-SvO2) [s delta(SaO2-SvO2)]: simple sum, root mean square (RMS) error, and RMS error with correction term. We derived the equation for the RMS error with correction term because initial results showed that the simple sum and RMS error methods did not predict s delta(SaO2-SvO2) well. The correction term accounts for the non-independence of simultaneous SaO2 and SvO2 measurements. RESULTS: The observed overall bias of the SaO2, SvO2, and (SaO2-SvO2) measurement methods were 0.17, -1.76, and 1.94, respectively. The observed overall s delta(SaO2-SvO2) of the (SaO2-SvO2) measurement method was 5.12. The simple sum method overestimated the actual s delta(SaO2-SvO2) by 38%, the RMS error method differed from the actual s delta(SaO2-SvO2) by 3%, and the RMS error with correction term method matched the actual s delta(SaO2-SvO2). CONCLUSION: The bias of a (SaO2-SvO2) measurement method is simply the bias of the SaO2 measurement method less the bias of the SvO2 measurement method. s delta(SaO2-SvO2) is best predicted by the derived equation, RMS error with correction term. The same principles and equations also apply to other situations in which 2 variables with the same dimensions are combined into 1 variable, such as (PaCO2-EtCO2) gradients and perfusion-pressure gradients. Although the difference between the s delta(SaO2-SvO2) predicted by the RMS error equation and the derived RMS error equation with correction term was small, the difference may be significant for other combined variables.

Oximetry↗
PubMed1997

[Cerebrovascular fiberoptic catheter oximetry in an intracranial pressure model in swine. New aspects of a clinical routine].

UNLABELLED: The reliability of continuous fibreoptic oximetry in cerebral venous blood and its correlation with intracranial and cerebral perfusion pressures (pressure-volume curve) were examined in an experimental porcine study. METHODS: The pressure in the infratentorial compartment of 13 domestic pigs (18-24 kg) was gradually increased by inflating a Fogarty balloon catheter placed on the surface of the right cerebellar hemisphere and below the tentorium. Single volumes of 0.4 ml saline were injected into the inflatable balloon at 1-min intervals up to a total volume of 7 ml. Intracranial pressure (ICP), arterial blood pressure, cerebral perfusion pressure (CPP), and cerebral venous saturation measured continuously by fibreoptic oximetry and intermittent blood-gas analyses (SjO2 superior sagittal sinus) were monitored during balloon inflation. All data were down-loaded onto a PC and evaluated off-line by a commercial statistical software package. RESULTS: Over the whole pressure-volume curve, two phases of SjO2 behaviour were registered by continuous fibreoptic oximetry (Oximetrix 3, Abbott) (Fig. 1). CPP ranges of less than 50% reduction from the initial value showed a linear correlation (rmittl. = 0.712, P < 0.01) between both parameters (CPP-SjO2). In CPP ranges below a crucial point of about 50 mmHg no such correlation was found (rmittl = 0.176, P < 0.5). In contrast, in 3 pigs a very good correlation was found between CPP and SjO2 over the whole pressure-volume curve as measured by blood-gas analyses of samples from the cerebrovenous catheter (rmittl. = 0.84, P < 0.05). DISCUSSION: We conclude that in physiological CPP ranges down to 50 mmHg, SjO2 measurement is a reliable method of detecting oxygen desaturation in cerebrovenous blood. Below that CPP value, the fibreoptic catheter showed repeated false-high oxygen saturation values. The accuracy of SjO2 measurement seems to depend on sufficient cerebral blood flow (CBF): with decreasing CBF the amount of cerebral venous outflow is diminished. We believe this is why we could not find a correlation in low CPP ranges with the oximetry catheter. This flow-dependency is a new aspect of fibreoptic cerebrovenous oximetry. The authors recommend that rising SjO2 values after desaturation events be confirmed by blood-gas analyses.

Animals↗
PubMed2004

Accuracy of pulse oximetry readings in an animal model of low perfusion caused by emerging pneumonia and sepsis.

OBJECTIVE: To test the effects of low perfusion caused by emerging sepsis on the performance of two new pulse oximetry techniques: Masimo SET in comparison with Nellcor Oxismart XL. DESIGN: Cohort study with random allocation of two pulse oximetry devices to two sensor sites. SETTING. University animal research facility. SUBJECTS: Twenty-five adult, anesthetized, ventilated rabbits. INTERVENTIONS: Pneumonia/sepsis was induced by tracheal instillation of E. coli. MEASUREMENTS AND RESULTS: Oxygen saturation was measured by pulse oximetry (SpO(2)) and recorded continuously until death. Arterial oxygen saturation (SaO(2)) was measured hourly by CO oximetry and whenever a difference of >5% between the devices occurred. SpO(2) sensors were positioned at both forelegs and switched hourly. There was no difference in total signal dropout time [median 3.8 min (range 0.4-66.6 min) vs 3.3 min (range 0-94.5 min), Masimo SET vs Oxismart XL]. There were fewer episodes with a false SpO(2) reading [1 (range 0-7) vs 2 (range 0-17)] using the Masimo SET vs the Oxismart XL as verified by CO oximetry; p<0.05. Average bias (SpO(2)-SaO(2)) was significantly different between the two devices, and variability of bias values increased across time with both devices. CONCLUSIONS: Both devices were capable to measure SpO(2) during most of the experimental time in this model of low perfusion and therefore appear to be highly sensitive to pick up a signal; however, low perfusion caused by emerging sepsis may result in inaccurate measurements with both devices. These episodes were less common with the Masimo SET vs the Oxismart XL.

Animals↗
PubMed2006

Decreased accuracy of pulse oximetry measurements during low perfusion caused by sepsis: Is the perfusion index of any value?

OBJECTIVE: To evaluate the effects of deteriorating perfusion caused by sepsis on the accuracy of pulse oximetry measurements using two more recently available techniques (Nellcor N-395 and Masimo Radical) and to evaluate the perfusion index as a marker of impaired peripheral perfusion to indicate that accuracy of pulse oximetry readings may be affected. DESIGN AND SETTING: Interventional cohort study in a university animal research facility. SUBJECTS: Thirty-seven adult anesthetized, ventilated rabbits. INTERVENTIONS: Pneumonia/sepsis was induced by tracheal instillation of Escherichia coli. MEASUREMENTS AND RESULTS: Oxygen saturation and perfusion index as a marker of peripheral perfusion were measured by pulse oximetry (SpO2) and recorded continuously for 8 h. Arterial oxygen saturation (SaO2) was measured every 30 min by CO oximetry, and bias (SpO2 - SaO2) was calculated at each time point for each device to assess time-dependent changes in bias. Bias increased significantly across time for both devices tested comparing the first with the second half of the experimental period. Bias measurements during the second half of the experimental time were beyond the +/-3% error limit in 21.4% of cases with Nellcor and in 22.6% with Masimo. A lower perfusion index was associated with increased bias, but sensitivity, specificity, and positive and negative predictive values of this marker for increased bias was very limited. CONCLUSIONS: We conclude that accuracy of pulse oximetry measurements was considerably affected with both devices with progressively deteriorating hemodynamics in this animal model of severe sepsis. Perfusion index as a marker for increased risk of bias was not a useful tool.

Animals↗
PubMedDate not supplied

Combining pulse oximetry and clinical examination in screening for congenital heart disease.

The objective of this study was to evaluate combined pulse oximetry and clinical examination as a screening method for congenital heart disease (CHD) in asymptomatic newborns. Asymptomatic newborns were screened for CHD using pulse oximetry and clinical examination before their discharge from the nursery. Oxygen saturation > or =94% was considered normal. Echocardiography was done for newborns with abnormal readings and for those with significant murmurs. Data concerning undetected cases were collected from the pediatric referral hospital. A total of 5211 cases were screened. Echocardiographic evaluations were done based on low pulse oximetry in five cases and on murmur detection in ten others. The sensitivity of the combined method of screening was 77%, whereas it was 31% for oximetry alone and 46% for clinical examination alone. Specificity was approximately 100% for all methods. The positive predictive value of the combined tool was 66.7%. We conclude that combining pulse oximetry and clinical examination can enhance the clinician's ability to detect life-threatening CHD in a timely manner. This screening method should become a part of the discharge plan for every newborn.

Echocardiography↗
PubMed1990

Value and accuracy of dual oximetry during pulmonary resections.

During thoracic surgery, one-lung ventilation (1LV) is often required. The purpose of this prospective study was to examine the usefulness and accuracy of dual-oximetry during 1LV. Prior to the induction of anesthesia, 30 patients had a radial artery and a fiberoptic pulmonary artery catheter (15 Edwards, 15 Spectramed by randomization) inserted. Arterial O2 saturation (SpO2) was monitored by pulse oximetry, and mixed venous O2 saturation (SvO2) by oximetry (Edwards or Spectramed). Arterial and mixed venous blood gases were obtained and immediately analyzed by an OSM3-Hemoximeter. Measurements, including hemodynamics and blood gases, were obtained before induction, during two-lung ventilation (2LV) in the supine and lateral decubitus positions, during 1LV, and following extubation. The change from 2LV to 1LV was associated with significant increases in cardiac index (CI) and oxygen delivery index (DO2I), whereas PaO2 and arterial and mixed venous oxygen saturation decreased. The ratio of oxygen consumption to delivery remained stable. Continuous oximetry when compared with in vitro measurements yielded a correlation coefficient for arterial oxygen saturation of r = 0.794 (P less than or equal to 0.001) and a value of bias and precision of -0.5% +/- 1.7%; for mixed venous oxygen saturation of r = 0.874 (P less than or equal to 0.001) and -1.3% +/- 2.8% for the two-wavelength Edwards catheter; and, r = 0.862 (P less than or equal to 0.001) and -0.1% +/- 3.2% for the two-wavelength Spectramed catheter. These findings demonstrate that dual-oximetry is an on-line, reliable method to measure SpO2 and SvO2. SpO2 less than 95% reflects hypoxygenation and hypoxia (PaO2 less than or equal to 70 mm Hg). SvO2 is determined primarily by oxygenation (r = 0.005; P less than or equal to 0.05) rather than by CI (r = 0.001, ns). Since DO2I increased during 1LV to maintain the oxygen supply and demand balance, SvO2 monitoring might be useful as an early indicator in identifying high-risk patients with compromised DO2I resulting from decreased CI.

Adult↗
PubMed1988

Continuous monitoring of gas exchange and oxygen use with dual oximetry.

The utility of integrated pulse and pulmonary artery oximetry, known as dual oximetry, was evaluated by monitoring 10 critically ill surgical patients for a total of 208 patient hours. The ventilation-perfusion index (VQI), an estimate of venous admixture, and the oxygen extraction index (O2EI), an estimate of tissue oxygen utilization coefficient, previously described, were calculated on-line from arterial and mixed venous oxyhemoglobin saturations using a computer. Effective monitoring was accomplished 85% of the total time. The dual oximetry device was nonfunctional owing to equipment failure only 15% of the time, even though no undue attention was given to instructing the staff on operation of the oximeters. Accuracy of VQI and O2EI was reconfirmed by this study. Drift in the saturations, VQI, and O2EI during the 6-h period between calibrations was negligible. The 95% range of random variability was +/- 2% for SaO2, +/- 3% for SvO2, +/- 5% for VQI, and +/- 0.04 for O2EI. Thirty-six episodes of arterial blood desaturation below 90% were detected by continuous oximetry. In contrast, 74 routine arterial blood samples revealed only four such episodes. Dual oximetry appears to be a technically reliable and accurate method of monitoring pulmonary gas exchange and tissue oxygen utilization. The equipment provided stable readings for at least six hours without recalibration. Random variability is sufficiently small to allow early detection of alterations in pulmonary and circulatory function without blood sampling.

Anesthesia, General↗
PubMed2005

Pulse oximetry in the adult ED patient with sickle cell.

We performed a retrospective chart review of adult patients with sickle cell presenting with vasoocclusive crisis to determine the association between pulse oximetry and emergency department (ED) disposition. Subjects were divided into a NORMAL (pulse oximetry > or = 95%) and a LOW (pulse oximetry <95%) group. Two hundred ten consecutive charts showed no significant difference between NORMAL (n = 163) and LOW (n = 47) groups regarding admission or discharge from the ED ( P > .05). A higher percentage in the LOW group received chest radiographs (40.9% vs 29%, P < .05), suggesting that pulse oximetry may have influenced ordering of this test. No significant differences in historical and physical exam characteristics were found. The pulse oximetry level does not appear to be associated with a particular ED disposition in adult sickle cell anemia.

Adult↗
PubMed2006

The effect of intrapartum fetal pulse oximetry, in the presence of a nonreassuring fetal heart rate pattern, on operative delivery rates: a multicenter, randomized, controlled trial (the FOREMOST trial).

OBJECTIVE: The objective of the study was to compare operative delivery rates for nonreassuring fetal status between 2 groups of laboring women: those having conventional cardiotocograph monitoring and those having cardiotocograph monitoring plus fetal pulse oximetry. STUDY DESIGN: The intrapartum fetal oximetry prospective, multicenter, randomized, controlled trial (the FOREMOST trial) was conducted in 4 Australian maternity hospitals. The primary outcome was operative birth rates for nonreassuring fetal status. RESULTS: There was a statistically significant 23% relative risk reduction in operative delivery for nonreassuring fetal status in the fetal pulse oximetry + cardiotocograph group (n = 75 of 305, 25%), compared with those in the cardiotocograph-only group (n = 95/295, 32%) (relative risk 0.77, 95% confidence interval 0.599, 0.999, P = .048). There were no significant between-group differences in overall operative births (fetal pulse oximetry + cardiotocograph group 73%, cardiotocograph-only group 71%, relative risk 1.04, 95% confidence interval 0.94, 1.15, P = .478) or neonatal outcomes. CONCLUSION: The use of fetal pulse oximetry to augment fetal well-being assessment during labor resulted in a statistically significant reduction in the operative intervention for nonreassuring fetal status, compared with the use of conventional cardiotocograph monitoring alone. This reduction was achieved with no significant difference in neonatal outcomes.

Adult↗
PubMed2005

Detection of a systolic pressure threshold for reliable readings in pulse oximetry.

OBJECTIVE: To determine the error of measurement in pulse oximetry with a decreased arterial perfusion and to identify a systolic pressure threshold for (1) initial detection and (2) a reliable reading of oxygen saturation. DESIGN: An experimental clinical prospective study. The study was approved by the local ethics committee. SETTING: Eighteen bed intensive care unit at a University hospital. PATIENTS AND PARTICIPANTS: Twenty-five adult mechanically ventilated and critically ill patients in the ICU during a 3-month period. INTERVENTIONS: A blood pressure cuff at the upper arm (same side as an arterial catheter already in place) was inflated to decrease the arterial pulsatile flow. The cuff was deflated stepwise and the resulting oxygen saturation was measured simultaneously. The error of measurement [delta S = SpO2 (baseline)-SpO2 (indicated)] was calculated for each 5 mmHg of blood pressure (BP). MEASUREMENTS AND RESULTS: Twenty-five patients (9 female, 16 male, 48 +/- 15.9 years old) with a mean SpO2 of 98.3 +/- 1.5% and a BP of 129 +/- 18.4 mmHg participated. The mean systolic BP to obtain initial readings with pulse oximetry was 45.8 +/- 17.7 (range, 25-101) mmHg (35% of the baseline pressure) resulting in lower readings of pulse oximetry (mean -11.5 +/- 13.6%, range -45 to +4%). With a systolic BP > 80 mmHg the mean bias was within the manufacturers limits of +/-2%. CONCLUSIONS: Pulse oximetry is reliable with a systolic blood pressure > 80 mmHg. The lower the BP, the lower the pulse oximetry readings leading to a bias of up to -45%.

Adult↗
PubMed2006

Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients.

INTRODUCTION: Nail polish of different colours may alter accuracy and precision of pulse oximetry as previous data in healthy volunteers suggest. This trial evaluates the oxygen saturation determined by pulse oximetry and haematoximetry with nail polish of nine different colours applied. MATERIAL AND METHODS: Fifty critically ill and mechanically ventilated patients in an ICU were investigated in a prospective clinical-experimental trial. On nine finger nails polish of different colours was applied in a predetermined consecutive order. Functional oxygen saturation was determined by pulse oximetry (SpO2) on each finger for each colour with the finger sensor probe both in the normal position and at a 90 degrees rotation. Simultaneously oxygen saturation was determined by haematoximetry (SaO2). Accuracy (bias, DeltaS = 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 (DeltaS = +1.6+/-3.0%), purple (DeltaS = +1.2+/-2.6%) and dark blue nail polish (DeltaS = +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 degrees reduced the bias from +2.8 to +1.3% (N = 10, n.s.). CONCLUSION: Nail polish does not alter pulse oximetry readings in mechanically ventilated patients to a clinically relevant extent. The mean error of measurement for all colours was within the manufacturers' specified range of +/-2%. A 90 degrees 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.

Adult↗
PubMed2003

Use of pulse oximetry to predict in-hospital complications in normotensive patients with pulmonary embolism.

PURPOSE: A simple method is needed to risk stratify normotensive patients with pulmonary embolism. We studied whether bedside clinical data can predict in-hospital complications from pulmonary embolism. METHODS: We performed a multicenter derivation phase, followed by validation in a single center. All patients were normotensive; the diagnosis of pulmonary embolism was established by objective imaging. Classification and regression analysis was performed to derive a decision tree from 27 parameters recorded from 207 patients. The validation study was conducted on a separate group of 96 patients to determine the derived criterion's diagnostic accuracy for in-hospital complications (cardiogenic shock, respiratory failure, or death). RESULTS: Mortality in the derivation phase was 4% (n = 8) at 24 hours and 10% (n = 21) at 30 days. A room-air pulse oximetry reading <95% was the most important predictor of death; mortality was 2% (95% confidence interval [CI]: 0% to 6%) in patients with pulse oximetry >or=95% versus 20% (95% CI: 12% to 29%) with pulse oximetry <95%. In the validation phase, the room-air pulse oximetry was <95% at the time of diagnosis in 9 of 10 patients who developed an in-hospital complication (sensitivity, 90%) and >or=95% in 55 of 86 patients without complications (specificity, 64%). CONCLUSION: Mortality from pulmonary embolism in normotensive patients is high. A room-air pulse oximetry reading >or=95% at diagnosis is associated with a significantly lower probability of in-hospital complications from pulmonary embolism.

Blood Pressure↗