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PubMed2000

Routine pulse oximetry during methacholine challenges is unnecessary for safety.

BACKGROUND: Methacholine-induced bronchoconstriction is associated with significant hypoxemia, which can be assessed noninvasively by transcutaneous oxygen tension and pulse oximetry. OBJECTIVES: To assess the value of the monitoring of finger pulse oximetry during routine methacholine challenges in a clinical pulmonary function laboratory with regard to both safety and the possibility that a significant fall in oxygen saturation as measured by pulse oximetry (SpO(2)) might be a useful surrogate for determining the response to methacholine. METHODS: Two hundred consecutive patients undergoing diagnostic methacholine challenges in the pulmonary function laboratory of a tertiary-care, university-based referral hospital were studied. Methacholine challenges were performed by the standardized 2-min tidal breathing technique, and the DeltaFEV(1) was calculated from the lowest postsaline solution inhalation to the lowest postmethacholine inhalation value. SpO(2) was measured immediately prior to each spirogram, and the DeltaSpO(2) was measured from the lowest postsaline solution inhalation value to the lowest postmethacholine inhalation value. We examined the data for safety (ie, any SpO(2) value < 90). Based on previous reports, we used a DeltaSpO(2) of > or = 3 as significant and looked at the sensitivity, specificity, and positive and negative predictive values for DeltaSpO(2) > or = 3 vis-à-vis a fall in FEV(1) of > or = 15%. RESULTS: There were 119 nonresponders (DeltaFEV(1), < 15%) and 81 responders. The baseline FEV(1) percent predicted was slightly but significantly lower in the responders (responders [+/- SD], 91.6 +/- 15%; nonresponders, 96.4 +/- 14%; p < 0.05). DeltaSpO(2) was 3.1 +/- 1.6 in the responders and 1.6 +/- 1.8 in the nonresponders (p < 0. 001). There was a single recording in one patient of SpO(2) < 90 (88). A DeltaSpO(2) > or = 3 had a sensitivity of 68%, a specificity of 73%, a positive predictive value of 63%, and negative predictive value of 77% for a fall in FEV(1) > or = 15%. CONCLUSIONS: Pulse oximetry is not routinely useful for safety monitoring during methacholine challenge. DeltaSpO(2) is not helpful in predicting a positive spirometric response to methacholine. However, the negative predictive value is adequate to allow the DeltaSpO(2) to be used as an adjunct in assessing a negative result of a methacholine test in patients who have difficulty performing spirometry.

Adolescent↗
PubMed1990

Reliability of pulse oximetry during exercise in pulmonary patients.

To evaluate the reliability of pulse oximetry during exercise, we studied 101 patients primarily with chronic pulmonary diseases. Three devices were used on different patients. Radial arterial blood was sampled at rest and maximal exercise simultaneously to pulse oximetric determination. Measured blood oxygen saturation was significantly different from noninvasive saturation at rest and also at exercise for each device. Nevertheless, changes in pulse oximetry from rest to exercise were significantly correlated with measured saturation for all three devices. Direction of changes in saturation from rest to exercise was correctly evaluated by transcutaneous oximetry in all but six instances where changes were less than 4 percent. Although measured and transcutaneous saturations are significantly different, we conclude that pulse oximetry reliably estimates changes in arterial saturation between rest and exercise for a clinical purpose. None of the three tested devices was better compared with the others in estimating saturation changes at exercise.

Adolescent↗
PubMed2005

Indications and limitations for a neonatal pulse oximetry screening of critical congenital heart disease.

AIMS: Critical congenital cardiovascular malformations (CCVMs) require surgical correction during the first month of life, physical examination is unable to detect >50% of affected infants. An oximetry screening has been previously proposed. Our aim was to verify the usefulness and consistency of a pulse oximetry screening for early detection of CCVMs in a small size nursery. METHODS: A single determination of SpO2 was performed on 5292 consecutive apparently healthy newborns, discharged from nursery at a median age of 72 h during the period May 1, 2000 and November 30, 2004. Infants showing signs of congenital heart disease before the screening and those with a prenatal diagnosis were excluded. Cardiac ultrasound was performed on all infants with SpO2< or =95% at >24 h. The accuracy of the screening in identifying CCVMs was assessed by receiver-operating characteristic (ROC) curves analysis. RESULTS: We found 2 (0.038%) true positives, 1 (0.019%) false negative, 1 (0.019%) false positive, and 5288 (99.92%) true negatives. Prevalence of critical CCVMs was 1 in 1764. Clinical follow-up showed no evidence of CCVMs in the negative cases. A pulse-oximetry cut-off value of < or =95% showed 66.7% sensitivity (95% CI: 11.6-94.5), 100% specificity (95% CI: 99.9-100.0), 50% positive predictive value, 100% negative predictive value and AUC of 0.833 (standard error: 0.145) (95% CI: 0.823 to 0.843) in identifying CCVMs. CONCLUSIONS: Our findings indicate that pulse oximetry is a non-invasive and specific screening tool for an early detection of CCVMs, and is easily applicable to a small size nursery.

Female↗
PubMed2006

Electron paramagnetic resonance oximetry as a quantitative method to measure cellular respiration: a consideration of oxygen diffusion interference.

Electron paramagnetic resonance (EPR) oximetry is being widely used to measure the oxygen consumption of cells, mitochondria, and submitochondrial particles. However, further improvement of this technique, in terms of data analysis, is required to use it as a quantitative tool. Here, we present a new approach for quantitative analysis of cellular respiration using EPR oximetry. The course of oxygen consumption by cells in suspension has been observed to have three distinct zones: pO(2)-independent respiration at higher pO(2) ranges, pO(2)-dependent respiration at low pO(2) ranges, and a static equilibrium with no change in pO(2) at very low pO(2) values. The approach here enables one to comprehensively analyze all of the three zones together-where the progression of O(2) diffusion zones around each cell, their overlap within time, and their potential impact on the measured pO(2) data are considered. The obtained results agree with previously established methods such as high-resolution respirometry measurements. Additionally, it is also demonstrated how the diffusion limitations can depend on cell density and consumption rate. In conclusion, the new approach establishes a more accurate and meaningful model to evaluate the EPR oximetry data on cellular respiration to quantify related parameters using EPR oximetry.

Animals↗
PubMed2003

Effectiveness of pulse oximetry screening for congenital heart disease in asymptomatic newborns.

OBJECTIVE: To determine the sensitivity, specificity, predictive value, and accuracy of a program of pulse oximetry screening of asymptomatic newborns for critical congenital cardiovascular malformation (CCVM). METHODS: Pulse oximetry was performed on asymptomatic newborns in the well-infant nurseries of 2 hospitals. Cardiac ultrasound was performed on infants with positive screens (saturation 24 hours). Data regarding true and false positives as well as negatives were collected and analyzed. RESULTS: Oximetry was performed on 11 281 asymptomatic newborns, and 3 cases of CCVM were detected (total anomalous pulmonary venous return x2, truncus arteriosus). During the study interval, there were 9 live births of infants with CCVM from a group of 15 fetuses with CCVM detected by fetal echocardiography. Six infants with CCVM were symptomatic before screening. There was 1 false-positive screen. Two infants with negative screens were readmitted (coarctation, hypoplastic left pulmonary artery with aorto-pulmonary collaterals). Other cardiac diagnoses in the database search were nonurgent, including cases of patent foramen ovale, peripheral pulmonic stenosis, and ventricular septal defect. The prevalence of critical CCVM among all live births was 1 in 564 and among the screened population was 1 in 2256 (sensitivity: 60%; specificity: 99.95%; positive predictive value: 75%; negative predictive value: 99.98%; accuracy: 99.97%). CONCLUSIONS: This screening test is simple, noninvasive, and inexpensive and can be administered in conjunction with state-mandated screening. The false-negative screen patients had lesions not amenable to detection by oximetry. The sensitivity, specificity, and predictive value in this population are satisfactory, indicating that screening should be applied to larger populations, particularly where lower rates of fetal detection result in increased CCVM prevalence in asymptomatic newborns.

Evaluation Studies as Topic↗
PubMed2005

Evaluating of veterinarians' and veterinary students' knowledge and clinical use of pulse oximetry.

RATIONALE FOR THE STUDY: We hypothesized that veterinarians and veterinary students may lack key knowledge about pulse oximetry, which may result in this type of patient monitor not being used on appropriate patient populations or to its full capabilities. METHODOLOGY: A questionnaire was developed to assess an individual's knowledge and understanding of pulse oximetry. Residents and specialists in anesthesiology and critical care at several academic institutions were surveyed first to assess the questionnaire for clarity and to serve as a control group. General veterinary practitioners (GPs) attending continuing education courses at the University of Georgia were surveyed over a 24-month period. Students entering their senior-year anesthesiology rotation at the University of Georgia were also surveyed. RESULTS: Residents and specialists (69% correct responses) scored significantly higher than senior students (46%), who scored significantly higher than GPs (34%). Only 15% of GPs and 21% of senior students reported that they had received training in pulse oximetry in school. Those who had received training scored significantly higher than those who had not. Many GPs did not report using a pulse oximeter on their critical patients under anesthesia, a group that would be expected to benefit from its use. CONCLUSIONS: Veterinarians have a poor understanding of how pulse oximetry works, the information it provides, and how best to apply it to their patients. Furthermore, the respondents did not use pulse oximeters in a manner that would yield the most information and result in the greatest benefit to the patient relative to the cost of the instrument. Didactic training in veterinary curricula and during continuing education opportunities continues to be necessary in order to produce veterinarians who have an understanding of the technologies available to improve patient care.

Animals↗
PubMed1990

Pulse oximetry: application in the pediatric and neonatal critical care unit.

The use of pulse oximetry in the pediatric and neonatal intensive care units has grown tremendously in recent years. Opinions about this growth are divergent. Arriving at a generalized statement about the accuracy of pulse oximeters is difficult, but it has generally been found to be acceptably accurate in most patient populations under most conditions. However, there are limitations to its application. Pulse oximetry accuracy can be adversely affected by elevated levels of certain abnormal hemoglobin varieties as well as motion artifact and low peripheral perfusion. Some authors suggest a caveat against the use of pulse oximetry to prevent hyperoxemia in the neonatal population, whereas others suggest it is an important advancement. The affect of the use of pulse oximetry on respiratory morbidity and mortality has not been established, and suggestions that all mechanically ventilated patients should be continuously monitored are unsubstantiated.

Child↗
PubMedDate not supplied

Pulse oximetry evaluation of vitality in primary and immature permanent teeth.

Present methods of assessing pulp vitality (electric and thermal testing) are of limited use with children, often resulting in false positive or false negative results. Pulse oximetry is a proven, atraumatic method of measuring vascular health by evaluating oxygen saturation (SaO2). This pilot study explores the use of a modified pulse oximetry ear probe to assess pulpal vascular oxygen saturation in primary and immature permanent teeth. Pulse oximetry readily differentiated between known vital and nonvital teeth. Vital teeth consistently provided SaO2 values that were lower than the values recorded on the patients' fingers. Further study of the SaO2 changes in traumatized teeth, with a probe designed specifically for teeth, is warranted by these initial results. Although additional research is indicated, pulse oximetry is already an objective, atraumatic clinical alternative to the present electrical and thermal methods of assessing pulp vitality in children's teeth.

Child↗
PubMed1999

Oximetry spectral analysis in the diagnosis of obstructive sleep apnoea.

Using spectral analysis of oximetry data, we prospectively evaluated the validity of this methodology in patients clinically suspected of suffering from obstructive sleep apnoea (OSA). A total of 233 outpatients were studied. Nocturnal oximetry was performed simultaneously with conventional polysomnography for all participants. The power density of oxygen saturation was analysed using Fast-Fourier transformation of the oximetric signal. Nocturnal oximetry test results were considered as abnormal (suspicion of OSA) if a peak in the spectrum between the period boundaries 30 and 70 s was observed. A normal test result was defined as the absence of the 30-70 s peak from the spectrum. Single-blind evaluation was performed by three independent observers, and agreement of two or more of these was considered definitive. The peak amplitude and the ratio of the area enclosed in the 30-70 s peak to the total area of the spectrum (r(S)) were measured. The presence of a peak has a sensitivity of 78%, a specificity of 89%, a positive predictive value of 89% and a negative predictive value of 78%. Apnoea-hypopnoea indexes were correlated significantly with peak amplitude (r=0.74; P<0.001) and with r(S) (r=0.69; P<0.001). For a peak amplitude threshold of 0.7%(2), the sensitivity was 94% and the specificity was 65% for OSA diagnosis. Using a threshold for r(S) of 0.15, the sensitivity was 91% and the specificity was 67%. Thus the spectral analysis of nocturnal oximetry and identification of a peak at 30-70 s could be useful as a diagnostic technique for OSA subjects.

Adult↗
PubMed2000

[Predictive value of nocturnal pulse oximetry in sleep apnea screening].

The monitoring of overnight oxygen saturation is widely used for sleep apnoea screening. The point of this screening has been questioned as a wide range of sensitivity has been reported in the literature. In a prospective study 70 subjects presenting with a possible sleep apnoea-hypopnoea syndrome had overnight oximetry followed by polysomnography 2 to 4 months later. Compared to polysomnography, the sensitivity of oximetry for sleep apnoea-hypopnoea was 85.2%, the specificity 77.8% and the predictive value positive 96.3%. When short, non-significant, repetitive desaturations have been declared pathologic, sensitivity increased to 91.8%. In the hands of an expert user, oximetry represents an excellent instrument for detecting patients with sleep apnoea-hypopnoea. Patients with pathological nocturnal oximetry are candidates for nCPAP treatment and therefore should undergo a sleep laboratory investigation.

Adult↗
PubMed2001

Prolonged interference of patent blue on pulse oximetry readings.

BACKGROUND: We evaluated the effect of intra-arterial injection of Patent Blue (PB) on pulse oximetry. METHODS: Ten consecutive female patients who underwent intra-arterial insertion of catheter for chemotherapy were enrolled in this study. All patients received general anesthesia and ECG, pulse oximetry, and direct arterial blood pressure were monitored throughout the perioperative period. Baseline arterial blood saturation (SpO2), haemoglobin concentration (Hgb), estimated arterial saturation (SaO2), arterial oxygen partial pressure (PaO2) were obtained through arterial blood gas analysis, and true arterial saturation (ScoO2) through CO-Oximetry analysis. The subsequent values obtained at various points of time following the intra-arterial administration of PB were compared with the baseline data. RESULTS: The SpO2 readings taken after intra-arterial injection of PB were significantly lower than the baseline reading. The extent of the reduction of SpO2 readings two hours after the administration of PB was relevant to the total accumulative dosage of PB (rs = -0.846, P < 0.05). However, the reduction of SpO2 bore no significant relation with Hgb concentration or with the ratio of PB dosage to Hgb concentration. CONCLUSIONS: Intra-arterial administration of PB interferes with pulse oximetry readings and the effect lasts for a variable duration. The extent of desaturation may be related to the total accumulative dosage of intra-arterial PB injected.

Adult↗
PubMedDate not supplied

Laser oximetry: A novel noninvasive method to determine changes in penile hemodynamics in an anesthetized rabbit model.

This study was designed to determine the utility and validity of laser oximetry in measuring changes in penile hemodynamics. Anesthetized male New Zealand White Rabbits were divided into 2 groups, and penile hemodynamics were assessed by either laser oximetry (oxyhemoglobin, deoxyhemoglobin concentration, and oxygen saturation) or intracavernosal pressure (ICP) monitoring during penile erection induced by pelvic nerve stimulation (PNS) or intracavernosal administration of phentolamine, nitroprusside, papaverine, or sildenafil. PNS caused significant frequency-dependent increases in penile ICP. PNS also caused significant increases in penile tissue oxyhemoglobin concentrations and tissue oxygen saturation in a frequency-dependent manner. The changes in oxyhemoglobin concentrations and oxygen saturation correlated with frequency-dependent increases in ICP. Intracavernosal vasoactive drug administration produced significant increases in ICP, tissue oxyhemoglobin concentration, oxygen saturation, and duration of response as a function of increasing drug concentration. Laser oximetry permits reproducible and valid assessment of changes in penile hemodynamics comparable to conventional ICP measurements. Thus, we consider laser oximetry a reliable technique in evaluating penile hemodynamics. Its sensitivity in detecting small changes in oxyhemoglobin concentration and its noninvasive nature make it advantageous over invasive methods such as ICP monitoring and laser Doppler flowmetry.

Animals↗
PubMed2002

Design and validation of pulse oximetry for low saturation.

As pulse oximetry migrates into new areas of patient care, it becomes increasingly important to rigorously test performance in the environment of use before claiming success. If evaluated only under tightly or ideally controlled laboratory or bench-top conditions, results may have little relationship to real-world behavior. As an example, fetal pulse oximetry sensors are subject to challenges not typically found with air-breathing patients. The "presenting part" is an attractive site for fetal oximetry, however the presence of resolvable pulses by itself does not ensure accurate readings. This study explores the effects of physiological and mechanical perturbations at low saturation expected during use on fetuses with such sensors. Numerical modeling and animal studies demonstrate that at 40% true arterial saturation (SaO2), calculated saturation values (SpO2) may err by more than 30%, even in the presence of otherwise normal pulse oximetry signals.

Computer Simulation↗
PubMed2003

Assessing need for long-term oxygen therapy: a comparison of conventional evaluation and measures of ambulatory oximetry monitoring.

BACKGROUND: Appropriate identification of hypoxic patients with chronic obstructive pulmonary disease (COPD) is important because of the demonstrated survival benefit of long-term oxygen therapy (LTOT) and its associated cost. Resting oxygen saturation (measured via pulse oximetry [S(pO2)]) and lowest exercise S(pO2) (during a 6-min walk test) is the standard method of determining LTOT requirements, but that method does not measure the patient's oxygenation during sleep or activities of daily living. We hypothesized that values obtained via the standard method would correlate poorly with values obtained via ambulatory oximetry monitoring. METHODS: We conducted a prospective, cohort study in an out-patient pulmonary clinic in a tertiary care referral center, with 20 stable COPD patients who were being evaluated for LTOT with conventional evaluation versus 16-24 hours of ambulatory oximetry. RESULTS: The resting S(pO2) did not correlate well with mean ambulatory S(pO2) (r = 0.64) or the percent of monitored time spent with S(pO2) < 88% (r = 0.49). The lowest exercise S(pO2) also did not predict mean ambulatory S(pO2) (r = 0.39) or the percent of monitored time spent with S(pO2) < 88% (r = 0.32). Conventional evaluation overestimated LTOT requirements with 16 of the 20 patients developing an S(pO2) < 88%, most of them with exercise only (ie, most had normal resting S(pO2)). With ambulatory monitoring, however, only 3 of the 16 patients spent > 10% of the monitored time with S(pO2) < 88%. CONCLUSION: There was a poor relationship between the conventional oxygenation assessment method and continuous ambulatory oximetry during LTOT screening with COPD patients.

Activities of Daily Living↗
PubMed2003

Neonatal and pediatric pulse oximetry.

The pulse oximeter has become a vital instrument in the care of infants and children with cardiopulmonary disease. Recent advances in pulse oximetry technology have improved some aspects of pulse oximeter performance. However, the reliability, accuracy, and clinical utility of pulse oximetry remain problematic in some types of patients under certain conditions. Improved signal processing technology has substantially improved the ability of certain oximeters to work reliably under conditions of poor perfusion and motion artifact. There is a growing body of evidence describing the effect of pulse oximeter utilization on processes and outcomes. This article describes the principles, limitations, current state of oximetry technology, and the impact of oximetry data and alarms on diagnosis and clinical decision-making.

Artifacts↗
PubMed2003

Does ambient light affect the accuracy of pulse oximetry?

OBJECTIVE: Determine whether ambient light affects the accuracy of pulse oximetry readings. DESIGN: Prospective, repeated-measures study. SETTING: A photographic darkroom. SUBJECTS: Forty-five faculty and students at a university, none of whom had pale skin, dark skin, or evidence of cardiopulmonary disease. Any nail polish was removed. METHODS: Five light sources were individually tested: incandescent, quartz-halogen, infrared, fluorescent, and bilirubin light. A pulse oximetry probe was placed on the subject's finger, and the finger and probe were placed sideways under each light source, on a predetermined mark. RESULTS: The greatest difference in pulse oximetry reading between any of the light sources was 0.5%. Repeated-measures analysis of variance yielded a p value of 0.204. CONCLUSIONS: Ambient light has no statistically significant effect on pulse oximetry readings. Even had the differences been statistically significant, the magnitude of the differences was small and thus clinically unimportant.

Adult↗
PubMed2003

Accuracy of pulse oximetry and capnography in healthy and compromised horses during spontaneous and controlled ventilation.

The objective of this prospective clinical study was to evaluate the accuracy of pulse oximetry and capnography in healthy and compromised horses during general anesthesia with spontaneous and controlled ventilation. Horses anesthetized in a dorsal recumbency position for arthroscopy (n = 20) or colic surgery (n = 16) were instrumented with an earlobe probe from the pulse oximeter positioned on the tip of the tongue and a sample line inserted at the Y-piece for capnography. The horses were allowed to breathe spontaneously (SV) for the first 20 min after induction, and thereafter ventilation was controlled (IPPV). Arterial blood, for blood gas analysis, was drawn 20 min after induction and 20 min after IPPV was started. Relationships between oxygen saturation as determined by pulse oximetry (SpO2), arterial oxygen saturation (SaO2), arterial carbon dioxide partial pressure (PaCO2), and end tidal carbon dioxide (P(et)CO2), several physiological variables, and the accuracy of pulse oximetry and capnography, were evaluated by Bland-Altman or regression analysis. In the present study, both SpO2 and P(et)CO2 provided a relatively poor indication of SaO2 and PaCO2, respectively, in both healthy and compromised horses, especially during SV. A difference in heart rate obtained by pulse oximetry, ECG, or palpation is significantly correlated with any pulse oximeter inaccuracy. If blood gas analysis is not available, ventilation to P(et)CO2 of 35 to 45 mmHg should maintain the PaCO2 within a normal range. However, especially in compromised horses, it should never substitute blood gas analysis.

Anesthesia, General↗
PubMed2004

Meconium-stained amniotic fluid and fetal oxygen saturation measured by pulse oximetry during labour.

BACKGROUND AND AIM OF THE WORK: The high false-positive rate of electronic fetal heart rate monitoring is the major obstacle to the correct prediction and diagnosis of intrapartum fetal distress. Fetal pulse oximetry is a safe and accurate indicator of fetal oxygenation. The aim of this study was to evaluate the clinical use of this technique for the diagnosis of fetal hypoxia and for prevention of fetal metabolic acidosis and asphyxia during labour, in the presence of meconium-stained amniotic fluid with or without abnormal fetal heart rate patterns, using a threshold value of 30% oxygen saturation. METHODS: Fetal blood oxygen saturation levels (SpO2) of 58 term fetuses with non-reassuring fetal status were measured during labour by fetal pulse oximetry. In 35 cases the amniotic fluid was stained with meconium at onset of labour. Mean SpO2 levels at the different stages of labour were matched against fetal heart rate patterns, the amniotic fluid status, and neonatal outcome. The 35 cases with meconium-stained amniotic fluid were compared with a control group of 28 pregnant women at term who had meconium-stained amniotic fluid during labour but were not monitored by pulse oximetry. RESULTS: When the fetal heart rate tracings were abnormal, mean SpO2values were significantly lower in the first 30 minutes of application and in the last 30 minutes of labour or before Cesarean section. Meconium-stained amniotic fluid was associated with lower SpO2values only when fetal heart monitoring showed a "non-reassuring" pattern. No cases were observed with severe neonatal acidosis, with Apgar score <7 at 5 minutes, or with other adverse neonatal events. In patients with meconium-stained amniotic fluid, neonatal outcomes were better in the group monitored by pulse oximetry versus the control group, although the differences were not statistically significant. CONCLUSIONS: Continued monitoring of fetal oxygen saturation combined with fetal heart rate monitoring may improve accuracy in the evaluation of fetal well-being. As a result, labour could be more safely managed in pregnancies with non-reassuring fetal status as measured by conventional methods, especially in the presence of meconium-stained amniotic fluid.

Adult↗