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PubMed1998

Pulse oximetry as a fifth vital sign in emergency geriatric assessment.

OBJECTIVE: To determine the utility of pulse oximetry as a routine fifth vital sign in emergency geriatric assessment. METHODS: Prospective study using pulse oximetry to measure O2 saturation in geriatric patients presenting to ED triage. Saturation values were disclosed to clinicians only after they had completed medical evaluations and were ready to release or admit each patient. The authors measured changes in medical management and diagnoses initiated after the disclosure of pulse oximetry values. The study included 1,963 consecutive adults aged > or = 65 years presenting to triage at a university ED. Measurements included changes in select diagnostic tests: chest radiography, complete blood count (CBC), spirometry, arterial blood gases (ABGs), pulse oximetry, and ventilation-perfusion scans; treatments: antibiotics, beta-agonists, and supplemental O2; and hospital admission and final diagnoses that occurred after complete ED evaluation when physicians were informed of triage pulse oximetry values. RESULTS: 397 (20.2%) geriatric patients had triage pulse oximetry values <95%. Physicians ordered repeat oximetry for 51 patients, additional chest radiography for 23, CBC for 16, ABGs for 15, spirometry for 5, and ventilation-perfusion scans for none. Physicians ordered 49 new therapies for 44 patients, including antibiotics for 14, supplemental O2 for 29, and beta-agonists for 6. Nine patients initially scheduled for ED release were subsequently admitted to the hospital. Physicians changed or added diagnoses for 27 patients. CONCLUSIONS: Using pulse oximetry as a routine fifth vital sign resulted in important changes in the diagnoses and treatments of a small proportion of emergency geriatric patients.

Aged↗
PubMed2000

Pulse oximetry: a new tool to assess patients with leg ulcers.

The objective of the study was to investigate pulse oximetry as a guide to assessing patients with leg ulcers before treatment. Graduated elastic compression is the treatment of choice for uncomplicated venous leg ulcers, but is contra-indicated in patients with significant arterial disease. The standard assessment of arterial insufficiency by Doppler ultrasound ankle branchial pressure index (ABPI) has shortcomings which prompted this investigation of pulse oximetry as a possible additional, or alternative, method of assessment of patients with leg ulcers, prior to treatment with compression. The study, carried out on a population of patients attending hospital leg ulcer clinics, was designed to evaluate pulse oximetry assessment in the selection and monitoring of patients with venous leg ulceration leading to a prospective controlled study of ulcer healing in groups of patients with reduced and normal ABPI, selected for compression therapy by pulse oximetry criteria. Outcome measurement required follow-up of patients selected for compression therapy by pulse oximetry to record time to healing and rate of healing of leg ulcers. Results from the study show a fair correlation between the toe-finger oximetry index (TFOI) and Doppler ABPI. There is no difference between ulcer healing in patients with reduced and normal ABPI selected for treatment on the basis of pulse oximetry maximum compression pressure (MCP). In conclusion, pulse oximetry is an aid to the selection of patients who will benefit from compression therapy, but would be excluded on the basis of Doppler ABPI.

Humans↗
PubMed1995

Effect of routine emergency department triage pulse oximetry screening on medical management.

PURPOSE: To determine the utility of routine triage pulse oximetry screening in emergency department (ED) patients. DESIGN: Prospective study using pulse oximetry to measure oxygen saturation of ED patients at triage. Saturation values were disclosed to physicians only after they completed medical evaluations and were ready to discharge or admit each patient. We measured changes in medical management initiated after disclosure of pulse oximetry values. SETTING AND PARTICIPANTS: The study included 14,059 consecutive patients presenting to triage at a university ED. MEASUREMENTS: Changes in select diagnostic tests: chest radiography, CBC count, spirometry, arterial blood gases, pulse oximetry, and ventilation-perfusion scans; treatments: antibiotics, beta-agonists, supplemental oxygen; and hospital admission and final diagnoses that occurred after disclosure of triage pulse oximetry values. RESULTS: Of 1,175 patients having triage pulse oximetry values less than 95%, physicians ordered repeat pulse oximetry on 159 (13.5%), additional chest radiography on 5.4%, CBC count on 3.1%, arterial blood gases on 2.9%, spirometry on 0.9%, and ventilation-perfusion scans on 0.3%. Physicians ordered 178 new therapies on 134 patients (11.4%), including supplemental oxygen for 6.5%, antibiotics for 3.9%, and beta-agonists for 1.8%. Thirty-five patients (3.0%) initially scheduled for hospital discharge were subsequently admitted. Physicians changed or added diagnoses in 77 patients (6.6%). CONCLUSIONS: Providing physicians with routine triage pulse oximetry measurements resulted in significant changes in medical treatment of these patients.

Adolescent↗
PubMed1998

Cost-effectiveness analysis of nocturnal oximetry as a method of screening for sleep apnea-hypopnea syndrome.

STUDY OBJECTIVE: Determine the utility of nocturnal oximetry as a screening tool for sleep apnea-hypopnea syndrome (SAHS) compared with polysomnography (PSG). DESIGN: Cost-effectiveness analysis based on retrospective review of overnight sleep studies. SETTING: United States Air Force tertiary teaching hospital. PATIENTS: One hundred consecutive patients evaluated for SAHS by overnight sleep study. INTERVENTION: Participants underwent PSG and oximetry on the same night. Patients with obstructive sleep apnea had a continuous positive airway pressure trial. MEASUREMENTS: Oximetry was abnormal when > or =10 events per hour occurred. Two criteria were evaluated. A "deep" pattern of > 4% change in oxyhemoglobin saturation to < or =90%, and a "fluctuating" pattern of repetitive short-duration fluctuations in saturation. The diagnostic accuracy of both methods was compared with PSG. Cost-effectiveness of screening oximetry was compared with PSG alone and use of split-night studies. RESULTS: The fluctuating pattern had a greater sensitivity and negative predictive value, while the deep pattern had a greater specificity and positive predictive value. Oximetry screening using the fluctuating pattern was not as sensitive as PSG for detecting patients with mild disease; 17 of 28 patients (61%) with normal oximetry results had treatable conditions detected by PSG. Cost analysis showed that screening oximetry would save $4,290/100 patients but with considerable loss of diagnostic accuracy. CONCLUSION: Screening oximetry is not cost-effective because of poor diagnostic accuracy despite increased sensitivity using the fluctuating pattern. Greater savings, without loss of diagnostic accuracy, may be achieved through increased utilization of split-night PSGs.

Adult↗
PubMed2005

Prospective evaluation of nocturnal oximetry for detection of sleep-related breathing disturbances in patients with chronic heart failure.

BACKGROUND: Because patients with chronic heart failure (CHF) can benefit from specific treatment for coexisting obstructive and central sleep apnea (CSA), there is a need to develop accurate screening tools to identify or exclude these sleep-related breathing disturbances (SRBDs) in patients with CHF. OBJECTIVES: To evaluate, prospectively, the diagnostic value of nocturnal home oximetry in identifying SRBD in CHF patients and in distinguishing central events from obstructive events. DESIGN: Blinded comparison of hospital and home oximetry, and polysomnographic nocturnal recordings SETTING: Cardiac heart failure and sleep clinics in three tertiary referral centers. PATIENTS: Fifty consecutive patients who were investigated for participation in the Canadian Continuous Positive Airway Pressure Trial for Congestive Heart Failure with Central Sleep Apnea and were recruited from three different centers. MEASUREMENTS AND RESULTS: Patients underwent two oximetry recordings, one at home and one during a polysomnographic study. The criterion for an SRBD was the presence of > 15 apneas and hypopneas per hour of sleep during polysomnography or an oxygen desaturation index of > 10 events per hour during oximetry. The pattern of desaturation/resaturation during oximetry was also examined to distinguish obstructive events from central events. Using a 2% fall in pulse oximetric saturation as the criterion for oxygen desaturation, home oximetry had a 85% sensitivity and a 93% specificity (p < 0.001) for detecting an SRBD. However, the desaturation/resaturation pattern did not accurately distinguish between obstructive events and central events (eg, 100% sensitivity, 17% specificity for identifying CSA). The interpretation of the oximetry recording was highly consistent between scorers (p < 0.001). CONCLUSIONS: Overnight home oximetry is a sensitive and specific tool for identifying SRBDs in patients with CHF, but not for distinguishing between obstructive and central events in such patients.

Adolescent↗
PubMed1997

Pulse oximetry as a fifth pediatric vital sign.

PURPOSE: To determine the utility of pulse oximetry as a routine fifth vital sign in acute pediatric assessment. DESIGN: Prospective study using pulse oximetry to measure oxygen saturation in children presenting to emergency department triage. Saturation values were disclosed to clinicians only after they had completed medical evaluations and were ready to discharge or admit each child. We measured changes in medical treatment and diagnoses initiated after the disclosure of pulse oximetry values. SETTING AND PARTICIPANTS: The study included 2127 consecutive children presenting to triage at a university emergency department. MEASUREMENTS: Changes in select diagnostic tests: chest radiography, complete blood count, spirometry, arterial blood gases, pulse oximetry, and ventilation-perfusion scans; treatments: antibiotics, beta-agonists, supplemental oxygen; and hospital admission and final diagnoses that occurred after disclosure of triage pulse oximetry values. RESULTS: Of 305 children having triage pulse oximetry values less than 95%, physicians ordered second oximetry for 49, additional chest radiography for 16, complete blood counts for 7, arterial blood gas measurements for 4, spirometry for 2, and ventilation-perfusion scans for 2. Physicians ordered 39 new therapies for 33 patients, including antibiotics for 15, supplemental oxygen for 11, and beta-agonists for 8. Five patients initially scheduled for hospital discharge were subsequently admitted. Physicians changed or added diagnoses in 25 patients. CONCLUSIONS: Using pulse oximetry as a routine fifth vital sign resulted in important changes in the treatment of a small proportion of pediatric patients.

Adolescent↗
PubMed1993

Utility of nocturnal home oximetry for case finding in patients with suspected sleep apnea hypopnea syndrome.

OBJECTIVE: To evaluate prospectively the validity of home oximetry for case finding in patients clinically suspected of having the sleep apnea hypopnea syndrome (SAHS). DESIGN: Blinded comparison of home oximetry and polysomnographic nocturnal recordings. SETTING: Sleep clinic of a tertiary referral center. PATIENTS: A total of 240 outpatients referred because of reported sleep disturbances or daytime hypersomnia compatible with the diagnosis of SAHS. MEASUREMENTS: All participants had nocturnal home oximetry followed by a conventional polysomnographic study. The two recordings were interpreted blindly. Home oximetry test results were classified as abnormal (suspicion of sleep-related breathing abnormalities) in the presence of repetitive, short-duration arterial oxyhemoglobin saturation. (SaO2) fluctuations without any absolute or relative decrease in the SaO2 threshold. The diagnosis of SAHS was confirmed when the apnea-plus-hypopnea index was greater than 10. RESULTS: Based on the results of the polysomnographic sleep study, 110 patients had SAHS (apnea-plus-hypopnea index, 38.1 +/- 2.5/h; mean +/- SE). Home oximetry test results were interpreted as abnormal in 176 patients (this included 108 patients with SAHS and 68 without SAHS) and were read as normal in 62 patients without SAHS and in 2 with SAHS. Home oximetry testing had a sensitivity of 108/110 or 98.2% (95% Cl, 93.6% to 99.8%); a specificity of 62/130 or 47.7% (Cl, 38.8% to 56.6%); a positive predictive value of 108/176 or 61.4%; and a negative predictive value of 62/64 or 96.9%. CONCLUSIONS: A negative home oximetry test result is helpful in ruling out the diagnosis of SAHS in patients clinically suspected of having this syndrome, because a negative test result reduced the probability from 54.1% to 3.1% in our patients. However, a positive oximetry test increased the probability from 46% to 61.4% in our group of patients.

Adult↗
PubMed2005

Does perioperative pulse oximetry improve outcome? Seeking the best available evidence to answer the clinical question.

The aim of this chapter is to clarify the effect of perioperative monitoring with pulse oximetry and to identify the adverse outcomes that might be prevented or improved by its use. Trials were identified by computerized searches of The Cochrane Library, MEDLINE and EMBASE, and by checking the reference lists of trials and review articles. All controlled trials that randomized patients to either pulse oximetry or no pulse oximetry during the perioperative period, including the operating and recovery room, were included in the search. Pulse oximetry monitoring was shown to substantially reduce the extent of perioperative hypoxaemia, enabling the detection and treatment of hypoxaemia and related respiratory events, and promoting several changes in patient care. The implementation of perioperative pulse oximetry monitoring does not significantly reduce the number of postoperative complications, but the question remains whether pulse oximetry can improve outcomes in other situations. Pulse oximetry has been adopted all over the world in clinical practice as a tool that guides anaesthesiologists in the daily management of patients: in teaching situations, in emergencies, and especially in the care of children. Given the relatively small number of patients studied in these trials and the rare events being sought, the studies of perioperative monitoring with pulse oximetry were not able to show an improvement in the outcomes studied.

Evidence-Based Medicine↗
PubMed2005

Use of fetal pulse oximetry among high-risk women in labor: a randomized clinical trial.

OBJECTIVE: The purpose of this study was to determine the clinical role of fetal pulse oximetry to reduce cesarean delivery for a nonreassuring fetal heart rate tracing. STUDY DESIGN: Singletons > or =28 weeks were randomized to fetal pulse oximetry plus electronic fetal heart rate monitoring (monitoring + fetal pulse oximetry) or monitoring alone. RESULTS: Overall, 360 women in labor were recruited: 150 cases with monitoring+fetal pulse oximetry and 177 cases with monitoring alone were analyzed. Most demographic, obstetric, and neonatal characteristics were similar. Specifically, the gestational age, cervical dilation, and station of the fetal head were not differential factors. In addition, cesarean delivery for nonreassuring fetal heart rate tracing was not different between the group with monitoring+fetal pulse oximetry (29%) and the group with monitoring alone (32%; relative risk, 0.95; 95% CI, 0.75, 1.22). Likewise, cesarean delivery for arrest disorder was similar between the group with monitoring+fetal pulse oximetry (22%) and the group with monitoring alone (23%; relative risk, 1.05; 95% CI, 0.79, 1.44). However, the decision-to-incision time was shorter for the group with monitoring+fetal pulse oximetry (17.8 +/- 8.2 min) than for the group with monitoring alone (27.7 +/- 13.9 min; P < .0001). CONCLUSION: The use of fetal pulse oximetry with electronic fetal heart rate monitoring does not decrease the rate of cesarean delivery, although it does alter the decision-to-incision time.

Adult↗
PubMed1995

The role of pulse oximetry. Its use as an indicator of severe respiratory disease in Peruvian children living at sea level. Respiratory Group in Peru.

OBJECTIVE: To evaluate pulse oximetry as a technique for diagnosing pneumonic and nonpneumonic acute lower respiratory tract infection (ALRI) in Peruvian children. DESIGN: Children with acute respiratory infection were diagnosed with hypoxemia by pulse oximetry, with ALRI by the World Health Organization (WHO) algorithm and clinical examination, and with pneumonia by radiographic examination. Diagnoses were compared using kappa analysis. SETTING: Pediatric emergency department. PATIENTS: Peruvian pediatric patients with acute respiratory infection (n = 269) and well children (n = 162). MAIN OUTCOME MEASURES: Hypoxemia (arterial oxygen saturation < 96.6% of the mean arterial oxygen saturation of well children -2 SD). RESULTS: Children with pneumonic and nonpneumonic ALRI (59%, 160/269) had a mean (+/- SD) arterial oxygen saturation significantly lower than well children (93.8% +/- 3.5% vs 98.7% +/- 1.51%; P < .01). Pulse oximetry detected 88% and the WHO algorithm 90% of cases of pneumonic ALRI. The WHO algorithm and pulse oximetry detected 72% of radiologic pneumonia. Pulse oximetry misclassified notably fewer well children than did the WHO algorithm (4% vs 35%). Pulse oximetry and the WHO algorithm together (SATWHO) detected 99% and 87% of pneumonic ALRI and radiologic pneumonias, respectively, and both methods detected 94% of all cases of pneumonic and nonpneumonic ALRI diagnosed clinically. CONCLUSIONS: Pulse oximetry and the WHO algorithm are practical, helpful, and appropriate for use in developing countries to identify children with pneumonic and non-pneumonic ALRI who require treatment. The SATWHO is highly sensitive for detecting children with ALRI.

Acute Disease↗
PubMed1989

Evaluation of the palmar circulation by pulse oximetry.

The usual method of substantiating collateral circulation of the hand is with Allen's test. We used the pulse-detecting capability of the pulse oximeter to assess the presence of collateral circulation of the hand. Thirty-one patients undergoing radial artery cannulation for intraoperative monitoring were evaluated before cannulation with a modified Allen's test and by pulse oximetry. After the collateral circulation of the hand was tested by the modified Allen's test, a pulse oximeter probe was placed on the index finger. Both radial and ulnar arteries were occluded until no perfusion was detected by the pulse oximeter. The test was repeated twice on each hand, once for each artery. The time to reperfusion after arterial release was recorded. Reperfusion times greater than 15 seconds were considered abnormal. This sequence was repeated postoperatively after the radial artery cannulae were removed. A total of 68 tests were performed before cannulation; 3 showed an abnormal Allen's test, a finding confirmed by pulse oximetry evaluation. The Allen's test was indeterminate 13 times. In all of these cases, pulse oximetry demonstrated collateral blood flow. When collateral circulation was determined to be present by Allen's test, it was also found to be present with pulse oximetry. Three days after cannulation was discontinued, 8 patients had abnormal Allen's test results, a finding again confirmed by pulse oximetry evaluation. Of 15 patients with indeterminate Allen's test results, 12 had collateral blood flow determined by pulse oximetry and 3 had abnormal results. The ability of pulse oximetry to detect collateral circulation was significantly different (P less than 0.001) when compared with Allen's test both before and after radial artery cannulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Intrapartum fetal pulse oximetry: present and future.

Pulse oximetry is widely used to monitor the patient's well-being in anesthetic and neonatal practice. As a result of recent technologic and theoretical advances, it has emerged as a clinical tool in intrapartum fetal monitoring. Oximeters record both pulse rate and arterial oxygen saturation of the fetus and they may be adapted to derive an estimate of peripheral perfusion. Reflectance oximetry is more accurate than transmission oximetry in intrapartum fetal management. This method uses the pulsatile changes of red and infrared light reflected from tissue to estimate arterial oxygenation. Pulse oximetry is cheap, non-invasive, simple to operate, relatively accurate and has a fast response time. Factors adversely affecting the accuracy of the pulse oximeter output include transducer displacement, peripheral vasoconstriction, hypotension, anemia, presence of intravascular dyes, meconium staining, fetal hair and scalp edema. Fetal pulse oximetry is limited by a wide normal range and inadequate calibration. The amniochorionic membranes however do not affect oximetry readings so that this method may be applied before rupture of the membranes, i.e. before labor. Once successfully developed, fetal pulse oximetry could potentially be used in combination with other monitoring techniques to reduce instrumental and operative interventions during labor and improve perinatal outcome.

Female↗
PubMed2005

Pulse oximetry does not reliably detect aspiration on videofluoroscopic swallowing study.

OBJECTIVE: To examine the reliability of pulse oximetry for identifying aspiration by comparing it with the videofluoroscopic swallowing study (VFSS). DESIGN: Nonrandomized, prospective, double-blind study. SETTING: VFSS laboratory in a teaching hospital. PARTICIPANTS: Sixty patients from among 130 patients with clinically diagnosed dysphagia between September and December 2002. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Simultaneously monitoring the arterial oxygen saturation (Sp o 2 ) by pulse oximetry while patients were performing VFSS. A decrease in Sp o 2 exceeding 3% was considered as significant desaturation. Bolus or portion of bolus passing through the vocal cords and entering the subglottic space was defined as aspiration on VFSS. The results of pulse oximetry and VFSS were compared. RESULTS: No significant correlation existed between desaturation measured by pulse oximetry and aspiration on VFSS (chi 2 test, P =.87). The positive predictive rate of pulse oximetry in detecting aspiration on VFSS was 39.1%, and the negative predictive rate was 59.4%. CONCLUSIONS: Aspiration occurring on VFSS cannot be predicted based on decrease in Sp o 2 in pulse oximetry. The application of pulse oximetry to detect aspiration during regular meals requires further investigation.

Deglutition↗
PubMed1998

Transcranial cerebral oximetry during carotid endarterectomy: agreement between frontal and lateral probe measurements as compared with an electroencephalogram.

OBJECTIVE: Transcranial cerebral oximetry, which is considered a novel technique, was evaluated during carotid endarterectomy. For practical reasons, the use of a single probe attached to the forehead and overlying the territory of the anterior cerebral artery is recommended. Other monitoring systems (transcranial Doppler, electroencephalograms (EEG)) focus more on the territory of the middle cerebral artery. The aim of this study was to evaluate whether a probe in the frontal area is as representative for monitoring cerebral ischaemia during carotid cross-clamping as a probe in the lateral area. DESIGN: Clinical prospective study. MATERIALS: Sixty patients who underwent carotid endarterectomy were studied with continuous and simultaneous EEG and transcranial cerebral oximetry. Forty-three patients (72%) simultaneously underwent frontal and lateral transcranial cerebral oximetry. The lateral probe was only used in 17 patients. METHODS: The percentage decrease of transcranial cerebral oximetry was calculated during cross-clamping. Using the EEG findings as the gold standard in order to detect cerebral ischaemia during carotid cross-clamping, the relationship with transcranial cerebral oximetry was described in terms of sensitivity, specificity and the area under the curve in a receiver operating characteristic curve. RESULTS: The 95% confidence interval of the area under the curve of the receiver operating characteristic of the lateral probe was 0.61-1.00 and that of the frontal probe was 0.65-1.00; therefore there is virtually no difference between the two methods. In 18% of the cases the lateral transcranial cerebral oximetry was hindered by practical failures. CONCLUSION: Considering the lack of additional information and the practical problems experienced with the lateral probe, it was concluded that transcranial cerebral oximetry with a single frontal probe is a practical non-invasive monitoring system and is at least as representative for monitoring cerebral ischaemia during carotid cross-clamping as a lateral probe.

Brain↗
PubMed1999

Endoluminal pulse oximetry of the sigmoid colon and the monitoring of the colonic circulation.

Colonic ischaemia is a frequently observed serious complication following abdominal aortic reconstruction. For adequate treatment of this disorder, early diagnosis and resection of the diseased colon is essential. The purpose of this study was to evaluate a new method, based on pulse oximetry, to detect colonic ischaemia at an early preclinical stage. During a 7-year period (1989-1995) colonoscopy and pulse oximetry were performed in all patients at risk of colonic ischaemia: complicated acute or elective aortic reconstructions, colostomies with superficial necrosis and in patients who underwent uncomplicated aortic reconstruction and non-ischaemic colonic problems (n = 90). The sensitivity, specificity and positive predictive values, and negative predictive value, were calculated. All patients, except four for whom an acute relaparotomy was necessary, subsequently underwent colonoscopy combined with endoluminal pulse oximetry. Of the 90 patients, 30 had colonic ischaemia according to endoscopy (n = 26) or relaparotomy (n = 4), and in 33 patients the absence of pulsatile signal was detected by means of pulse oximetry. Thus, in three patients, pulse oximetry was falsely positive for colonic ischaemia. The calculated sensitivity and specificity of pulse oximetry were 100 and 95%, respectively. In comparison to other methods used for early detection of colonic ischaemia, pulse oximetry appears to be a promising method for the evaluation and monitoring of colonic ischaemia because it is non-invasive and easy to apply with a high sensitivity and specificity.

Adult↗
PubMed2006

Do clinicians know how to use pulse oximetry? A literature review and clinical implications.

Pulse oximetry has become one of the most commonly used tools in the clinical environment for assessing patients' oxygenation status. It is employed almost continuously in critical care areas and frequently in the general ward environment. Although it is a much better tool for determining hypoxia than the human eye, its use is limited if clinicians do not understand relevant physiological principles, such as the oxyhaemoglobin dissociation curve and the inherent limitations of the device. Furthermore, the risk for compromised patient safety is significant if clinicians fail to recognise the potential for false or erroneous readings. This paper explores the research which has examined clinicians' comprehension of pulse oximetry. Fourteen studies examining clinicians' knowledge of pulse oximetry were reviewed. These studies revealed significant knowledge deficits about pulse oximetry amongst nurses, doctors and allied health professionals, all of whom used this technology frequently. Alarmingly, those lacking an adequate understanding of pulse oximetry included senior, experienced clinicians. The studies were limited by their use of convenience sampling and small sample sizes. Further research is needed to better understand the significance of this problem and to examine how principles of pulse oximetry are taught to nurses and other health professionals at the undergraduate and postgraduate levels. Educators and clinicians alike must ensure that a safe level of knowledge for the use of pulse oximetry is maintained in order to ensure that patient outcomes are not compromised.

Clinical Competence↗
PubMed2000

Masimo signal extraction pulse oximetry.

OBJECTIVE: To describe a new pulse oximetry technology and measurement paradigm developed by Masimo Corporation. INTRODUCTION: Patient motion, poor tissue perfusion, excessive ambient light, and electrosurgical unit interference reduce conventional pulse oximeter (CPO) measurement integrity. Patient motion frequently generates erroneous pulse oximetry values for saturation and pulse rate. Motion-induced measurement error is due in part to widespread implementation of a theoretical pulse oximetry model which assumes that arterial blood is the only light-absorbing pulsatile component in the optical path. METHODS: Masimo Signal Extraction Technology (SET) pulse oximetry begins with conventional red and infrared photoplethysmographic signals, and then employs a constellation of advanced techniques including radiofrequency and light-shielded optical sensors, digital signal processing, and adaptive filtration, to measure SpO2 accurately during challenging clinical conditions. In contrast to CPO which calculates O2 saturation from the ratio of transmitted pulsatile red and infrared light, Masimo SET pulse oximetry uses a new conceptual model of light absorption for pulse oximetry and employs the discrete saturation transform (DST) to isolate individual "saturation components" in the optical pathway. Typically, when the tissue under analysis is stationary, only the single saturation component produced by pulsatile arterial blood is present. In contrast, during patient motion, movement of non-arterial components (for example, venous blood) can be identified as additional saturation components (with a lower O2 saturation). When conditions of the Masimo model are met, the saturation component corresponding to the highest O2 saturation is reported by the instrument as SpO2. CONCLUSION: The technological strategies implemented in Masimo SET pulse oximetry effectively permit continuous monitoring of SpO2 during challenging clinical conditions of motion and poor tissue perfusion.

Artifacts↗
PubMed2003

Feasibility of simultaneous application of fetal electrocardiography and fetal pulse oximetry.

BACKGROUND: Fetal pulse oximetry measures arterial oxygen saturation during delivery. The fetal electrocardiogram STAN S21 analyzes the repolarisation segment of ECG (ST) waveform, which is altered by the intramyocardial potassium release resulting from metabolic acidemia. This study aimed to evaluate the feasibility of a simultaneous application of pulse oximetry and fetal electrocardiography and to estimate any agreement between both methods indicating fetal compromise. METHODS: In an observational trial 35 fetuses were simultaneously monitored by pulse oximetry (OBS-500) and electrocardiography. The evaluation focused on signal output and on the coincidence of desaturation in fetal pulse oximetry and on ST events. Desaturation was defined as a drop of at least 20% of oxygen saturation from base line level occurring within 1 min (steep desaturation) or duration of time (s) with oxygen saturation below the threshold of 30%. Statistical analysis was performed with the Mann-Whitney U-test for continuous variables. RESULTS: Signal output of the simultaneous application of both sensors was not significantly reduced in the electrocardiogram and in pulse oximetry (8% vs. 12% reduction). In 15 of the 35 fetuses, ST events indicating fetal hypoxia occurred. In these cases, pulse oximetry showed significantly more episodes of desaturation in comparison with fetuses without ST events. Median saturation during the ST events was significantly lower than in the recordings without ST events (60% vs. 74%, p < 0.05). In the umbilical artery these neonates showed significantly lower pH (7.19 vs. 7.33, p < 0.001), significantly higher lactate (5.1 vs. 3.4 mmol/l, p < 0.05) and significantly lower base deficit (-9.4mmol/l vs. -4.0 mmol/l, p < 0.001) levels. CONCLUSIONS: The combination of fetal pulse oximetry and fetal electrocardiography appears feasible and indicates signs of intermittent hypoxia. These findings may encourage the development of technology that combines these different methods of monitoring.

Adult↗