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PubMed2004

Factors influencing fetal pulse oximetry performance.

Fetal pulse oximetry shares many problems with traditional pulse oximetry, but also poses unique challenges that may compromise accurate SpO2 determination and data availability. The purpose of this review is to characterize the factors that may influence fetal pulse oximetry and their relationship to sensor design. A review of the literature of pulse oximetry identifies the factors that have been shown to influence fetal pulse oximetry performance, as well as other factors from traditional pulse oximetry that may also be expected to have an effect. Sensor design choices, including monitoring site, wavelength, and configuration, are related to the incidence and mitigation of these factors. Sensor designs may be characterized by monitoring site, means of retention, and operating mode (reflectance versus transmission). The factors influencing fetal pulse oximetry may be categorized as follows: fetal physiology, tissue characteristics at the monitoring site, sensor-tissue interface, and external influences. Monitoring site selection is of paramount importance in reducing the impact of interfering factors on fetal pulse oximetry performance. Many factors of importance in traditional pulse oximetry have yet to be characterized as far as their potential for interference in fetal pulse oximetry.

Equipment Design↗
PubMed1993

Randomized evaluation of pulse oximetry in 20,802 patients: II. Perioperative events and postoperative complications.

BACKGROUND: The authors describe the effect of pulse oximetry monitoring on the frequency of unanticipated perioperative events, changes in patient care, and the rate of postoperative complications in a prospective randomized study. METHODS: The study included 20,802 surgical patients in Denmark randomly assigned to be monitored or not with pulse oximetry in the operating room (OR) and postanesthesia care unit (PACU). RESULTS: During anesthesia and in the PACU, significantly more patients in the oximetry group had at least one respiratory event than did the control patients. This was the result of a 19-fold increase in the incidence of diagnosed hypoxemia in the oximetry group than in the control group in both the OR and PACU (P < 0.00001). In the OR, cardiovascular events were observed in a similar number of patients in both groups, except myocardial ischemia (as defined by angina or ST-segment depression), which was detected in 12 patients in the oximetry group and in 26 patients in the control group (P < 0.03). Several changes in PACU care were observed in association with the use of pulse oximetry. These included higher flow rate of supplemental oxygen (P < 0.00001), increased use of supplemental oxygen at discharge (P < 0.00001), and increased use of naloxone (P < 0.02). The rate of changes in patient care as a consequence of the oximetry monitoring increased as the American Society of Anesthesiologists physical status worsened (P < 0.00001). One or more postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group (difference not significant). The two groups did not differ significantly in cardiovascular, respiratory, neurologic, or infectious complications. The duration of hospital stay was a median of 5 days in both groups (difference not significant). An equal number of inhospital deaths were registered in the two groups. Questionnaires, completed by the anesthesiologists at the five participating departments, revealed that 18% of the anesthesiologists had experienced a situation in which a pulse oximeter helped to avoid a serious event or complication and that 80% of the anesthesiologists felt more secure when they used a pulse oximeter. CONCLUSIONS: This study demonstrated that pulse oximetry can improve the anesthesiologist's ability to detect hypoxemia and related events in the OR and PACU and that the use of the oximeter was associated with a significant decrease in the rate of myocardial ischemia. Although monitoring with pulse oximetry prompted a number of changes in patient care, a reduction in the overall rate of postoperative complications was not observed.

Adult↗
PubMed1996

Predictors of pulse oximetry data failure.

BACKGROUND: Pulse oximeters have been reported to fail to record data in 1.12-2.50% of cases in which anesthesia records were handwritten. There is reason to believe that these may be underestimates. Computerized anesthesia records may provide insight into the true incidence of pulse oximetry data failures and factors that are associated with such failures. METHODS: The current study reviewed case files of 9,203 computerized anesthesia records. Pulse oximetry data failure was defined as the presence of at least one continuous gap in data > or = 10 min in duration in a case. A multivariate logistic regression model was used to identify predictors of pulse oximetry data failure, and a modified case-control method was used to determine whether extremes of blood pressure and hypothermia during the procedure were associated with pulse oximetry data failure. RESULTS: The overall incidence of cases that had at least one continuous gap of > or = 10 min in pulse oximetry data was 9.18%. The independent preoperative predictors of pulse oximetry data failure were ASA physical status 3,4, or 5 and orthopedic, vascular, and cardiac surgery. Intraoperative hypothermia, hypotension, hypertension, and duration of procedure were also independent risk factors for pulse oximetry data failure. CONCLUSIONS: Pulse oximetry data failure rates based on review of computerized records were markedly greater than those previously reported. Physical status, type of surgery, and intraoperative variables were risk factors for pulse oximetry data failure. Regulations and expectations regarding pulse oximetry monitoring should reflect the limitations of the technology.

Humans↗
PubMed2006

Continuous monitoring of central venous oxygen saturation in neonates and small infants: in vitro evaluation of two different oximetry catheters.

BACKGROUND: Accurate assessment and monitoring of the cardiocirculatory function are essential during major pediatric and pediatric cardiac surgery. Monitoring of the central venous oxygen saturation (ScvO(2)) may be a better indicator of tissue oxygenation and derangement of cellular oxygen utilization than the more commonly used vital parameters. Therefore, we compared oxygen saturation measurements with thin fiberoptic oximetry catheters and standard blood gas oximetry in an in vitro setting. METHODS: Two different size continuous fiberoptic oximetry catheters (2-4-F) were inserted in an extracorporeal circuit filled with human red blood cells in normal saline (haematocrit 30%, flow 600 ml.min(-1)). The results of fiberoptic oximetry were then compared with standard blood gas oximetry for a wide range of different oxygen saturations using linear regression. RESULTS: The oxygen saturations found ranged from 9% to 100%. The results of the two different fiberoptic oximetry catheters correlated significantly (r = 0.99, P < 0.0001) with standard blood gas oximetry. CONCLUSION: The results of fiberoptic oximetry are nearly identical with standard blood gas oximetry for a wide range of different oxygen saturations. Thin oximetry catheters can be inserted percutaneously even in neonates and small infants. The continuous monitoring of ScvO(2) may be beneficial, especially in patients who are in danger of developing low cardiac output or sudden cardiovascular collapse.

Blood Gas Monitoring, Transcutaneous↗
PubMed1997

Confirmation of the pulse oximetry gap in carbon monoxide poisoning.

STUDY OBJECTIVES: To demonstrate the degree to which pulse oximetry overestimates actual oxyhemoglobin (O2Hb) saturation in patients with carbon monoxide (CO) poisoning. This phenomenon has been reported in fewer than 20 humans in the English medical literature. METHODS: A retrospective chart review of 191 patients evaluated for CO poisoning at a regional hyperbaric center identified 124 patients 10 years of age and older who had had both arterial blood gas and pulse oximetry measurements and who had received either high-flow oxygen through a nonrebreather mask or 100% inspired oxygen through an endotracheal tube. Blood gas measurements, including direct spectrophotometric determination of O2Hb and carboxyhemoglobin (COHb) saturation values, were compared with finger-probe pulse oximetry readings. RESULTS: Measured O2Hb saturation (mean +/- SD, 88.7 +/- 10.2%; range, 51.4% to 99.0%) decreased linearly and predictably with rising COHb levels (10.7 +/- 10.4%; range, .2% to 46.4%). Pulse oximetry saturation (99.2% +/- 1.3%; range, 92% to 100%) remained elevated across the range of COHb levels and failed to detect decreased O2Hb saturation. The pulse oximetry gap, defined as the difference between pulse oximetry saturation and actual O2Hb saturation (10.5% +/- 9.7%; range, 0% to 40.6%), approximated the COHb level. CONCLUSION: There is a linear decline in O2Hb saturation as COHb saturation increases. This decline is not detected by pulse oximetry, which therefore overestimates O2Hb saturation in patients with increased COHb levels. The pulse oximetry gap increases with higher levels of COHb and approximates the COHb level. In patients with possible CO poisoning, pulse oximetry must be considered unreliable and interpreted with caution until the COHb level has been measured.

Adolescent↗
PubMed2003

Pulse oximetry for perioperative monitoring: systematic review of randomized, controlled trials.

Monitoring with pulse oximetry might improve patient outcome by enabling an early diagnosis and, consequently, correction of perioperative events that might otherwise cause postoperative complications or even death. The aim of the study was 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, 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 in the operating and recovery room, were included in the study. The search identified six reports. Of these 6 reports, 4 studies with data from 21,773 patients were considered eligible for analysis. Two studies specifically addressed the outcomes in question; both found no effect on the rate of postoperative complications using perioperative pulse oximetry. Hypoxemia was reduced in the pulse oximetry group both in the operating room and in the recovery room. During observation in the recovery room, the incidence of hypoxemia in the pulse oximetry group was 1.5-3 times less. There were postoperative complications in 10% of the patients in the oximetry group and in 9.4% in the control group. The duration of hospital stay was a median of 5 days in both groups, and an equal number of in-hospital deaths was registered in both groups. The studies confirmed that pulse oximetry could detect hypoxemia and related events. However, given the relatively small number of patients studied and the rare events being sought, the studies were not able to show an improvement in various outcomes.

Blood Gas Analysis↗
PubMed2004

Planning adenotonsillectomy in children with obstructive sleep apnea: the role of overnight oximetry.

OBJECTIVE: Obstructive sleep apnea (OSA) in children is usually effectively treated by adenotonsillectomy (T&A). However, there may be a waiting list for T&A, and the procedure is associated with an increased risk of postoperative complications in children with OSA. Needed is a simple test that will facilitate logical prioritization of the T&A surgical list and help to predict children who are at highest risk of postoperative complications. The objective of this study was to develop and validate a severity scoring system for overnight oximetry and to evaluate the score as a tool to prioritize the T&A surgical list. METHODS: This study comprised 3 phases. In phase 1, a severity score was developed by review of preoperative overnight oximetry in children who had urgent T&A in 1999-2000. In phase 2, the score was validated retrospectively in 155 children who had polysomnography (PSG) before T&A in 1992-1998. In a phase 3, a 12-month prospective evaluation of a protocol based on the score was conducted. RESULTS: In phase 1, a 4-level severity score was developed on the basis of the number and the depth of desaturation events (normal to severely abnormal, categories 1-4). In phase 2, the McGill oximetry score correlated with severity of OSA by PSG criteria. In phase 3, a clinical management protocol was developed based on the score. Of 230 children tested, 179 (78%) had a normal/inconclusive oximetry (category 1) and went on to have PSG. Those with a positive oximetry (categories 2-4; 22%) had no additional sleep studies before T&A. Timing of T&A was based on oximetry score, leading to a significant reduction in waiting time for surgery for those with higher oximetry scores. Postoperative respiratory complications were more common with increasing oximetry score. CONCLUSIONS: Overnight pulse oximetry can be used to estimate the severity of OSA, to shorten the diagnostic and treatment process for those with more severe disease, and to aid clinicians in prioritization of T&A and planning perioperative care.

Adenoidectomy↗
PubMed2005

Use of ambulatory overnight oximetry to investigate sleep apnea in a general internal medicine practice.

OBJECTIVE: To examine how clinical factors and results from ambulatory overnight oximetry related to recommendations for further sleep evaluation in patients with clinically suspected obstructive sleep apnea syndrome. PATIENTS AND METHODS: We reviewed 100 medical records selected randomly from 375 consecutive patients for whom ambulatory overnight oximetry had been ordered by internists and completed between September 1, 2001, and May 1, 2002. We analyzed relationships among clinical Information, oximetry results, resultant recommendations, and patient follow-up data. RESULTS: Only 21 of 100 patients had normal results from ambulatory overnight oximetry; 5 were referred for further sleep consultation. Abnormal results from ambulatory overnight oximetry were seen in 79 patients, but only 51 were referred for further sleep evaluation. Abnormal results from ambulatory overnight oximetry were associated with only a small increased likelihood of referral (likelihood ratio, 2.7; confidence interval, 1.2-6.0). Those with an oxygen desaturation index (number of desaturation events per hour of recording time) of greater than 15 received sleep consultation at a median of 8 days after completion of oximetry, whereas those with an oxygen desaturation index of 6 to 10 were evaluated in a median of 42 days (P=.60). All 17 patients who had minimum oxygen saturation of less than 80% were referred for further evaluation. CONCLUSIONS: Abnormal results from ambulatory overnight oximetry per se may not substantially influence internist referral of patients with clinically suspected sleep apnea for further sleep evaluation. Rather, severity of oximetry abnormalities is used along with other patient-related factors and sleep study accessibility to prioritize the need and urgency of further evaluation.

Female↗
PubMed1994

Anesthesia related hypoxemia. The effect of pulse oximetry monitoring on perioperative events and postoperative complications.

The objectives of the present investigation were to evaluate the extent of perioperative hypoxemia and to investigate the impact of pulse oximetry monitoring on the extent of hypoxemia and on perioperative morbidity in adults. To accomplish these objectives a number of prospective studies were carried out. The incidence, duration, and severity of hypoxemia were evaluated in two single blinded observer studies in the operating room (N = 296) (I) and in the Postanesthesia Care Unit (N = 200) (II). Pulse oximetry monitoring's effect on the extent of hypoxemia was evaluated in a randomized blinded observer study of 200 patients (III). The impact of pulse oximetry on the frequency of perioperative events, changes in patient care, and post-operative complications were studied in a randomized evaluation of 20,802 patients (IV-V). Finally, a subgroup of 736 patients already included in the randomized evaluation was psychologically evaluated pre- and postoperatively (VI). In the observer studies in the OR and PACU mild hypoxemia (SpO2 86-90%) was recorded in 53% and 55% of the patients, respectively. Severe hypoxemia with SpO2 values < 81% was recorded in 20% and 13% of the patients, respectively. In the randomized blinded observer study, patients with pulse oximeter data available had a significantly reduced incidence of perioperative hypoxemia when compared to patients where the data were unavailable. Most noteworthy was that in the available group extreme hypoxemia (SpO2 < 76%) was not encountered in the OR and both severe (SpO2 76-80%) and extreme hypoxemia were not observed in the PACU. In the randomized evaluation of pulse oximetry significantly more patients in the oximetry group experienced at least one respiratory event than did control patients in both the OR and in the PACU. This was a result of a 19 fold increase in the incidence of diagnosed hypoxemia in the oximetry group than in the control group. In the OR cardiovascular events were observed in a similar number of patients in both groups, except myocardial ischemia, which was detected in 12 patients in the oximetry group and in 26 patients in the control group (P < 0.03). Several changes in PACU care were observed in association with the use of pulse oximetry. These included higher flow rates of supplemental oxygen (P < 0.00001), increased use of supplemental oxygen at discharge (P < 0.00001), and increased use of naloxone (P < 0.02). One or more postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group (NS).(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia↗
PubMed2005

Pulse oximetry as a potential screening tool for lower extremity arterial disease in asymptomatic patients with diabetes mellitus.

BACKGROUND: Lower extremity arterial disease (LEAD) is common and underdiagnosed in patients with diabetes mellitus and is associated with higher total mortality. METHODS: We compared the accuracy of pulse oximetry, the ankle-brachial index (ABI), and the combination of the two to diagnose LEAD in consecutive outpatients with type 2 diabetes who had no symptoms of LEAD, in a primary care setting. Exclusions were age younger than 40 years, known LEAD, or typical symptoms of LEAD. Fifty-seven patients were enrolled. All patients had (1) ABI measurement; (2) pulse oximetry to measure Sao2 of their index fingers and big toes in the supine position and at 12-in elevation; and (3) Doppler waveform analysis of the lower extremity arteries. The ABI was considered abnormal if it was less than 0.9. Pulse oximetry of the toes was considered abnormal if the Sao2 was more than 2% lower from the finger or on 12-in elevation of the foot. The combination was considered positive if either the ABI or pulse oximetry was positive for LEAD and negative if both were negative. We defined LEAD as monophasic waveforms on waveform analysis. RESULTS: Of our patients, 31% had LEAD. Pulse oximetry had a sensitivity of 77% (95% confidence interval [CI], 61%-88%) and a specificity of 97% (95% CI, 91%-99%); ABI had a sensitivity of 63% (95% CI, 46%-77%) and a specificity of 97% (95% CI, 91%-99%). Positive likelihood ratios were 30 (95% CI, 7.6-121) for pulse oximetry and 24.8 (95% CI, 6.2-99.8) for ABI; negative likelihood ratios were 0.23 (95% CI, 0.12-0.43) for pulse oximetry and 0.38 (95% CI, 0.25-0.59) for ABI. For the combination, sensitivity was 86% (95% CI, 71%-94%) and specificity was 92% (95% CI, 84%-96%). CONCLUSIONS: Pulse oximetry of the toes seems as accurate as ABI to screen for LEAD in patients with type 2 diabetes. Combination of the two tests increases sensitivity.

Adult↗
PubMed2006

Respiratory changes in the pulse-oximetry waveform associated with pericardial tamponade.

BACKGROUND: Timely identification of hemodynamic compromise in patients with acute pericardial effusion and tamponade is critical in patient management. Respiratory variability in pulse-oximetry waveforms has been correlated with pulsus paradoxus, but has not been reported with cardiac tamponade in adult patients. HYPOTHESIS: This study describes changes in respiratory variability in pulse-oximetry waveform pre and post pericardiocentesis in patients with hemodynamically significant pericardial effusions. METHODS: A single-center, catheterization laboratory hemodynamic database was reviewed for all patients who underwent pericardiocentesis for clinically suspected tamponade and had continuous digital pulse-oximetry, electrocardiographic, and respiration waveforms recorded during the procedure. Phasic respiratory changes in pulse-oximetry waveform amplitude (maxima-minima) were expressed as an expiratory/inspiratory ratio and compared pre and post pericardiocentesis. RESULTS: The study population consisted of 12 patients (6 men:6 women, age 60 +/- 10 years) with pericardial effusion documented by echocardiography on the day of pericardiocentesis. Phasic respiratory variability in the pulse-oximetry waveform was evident in all patients prior to aspiration (respiratory ratio = 1.9 +/- 0.5). Following pericardiocentesis (aspirated volume: 650 +/- 300 ml), the respiratory ratio decreased in all patients (1.2 +/- 0. 1, p = 0.001). Receiver operator characteristic curve analysis suggests that pulse-oximetry respiratory ratios > or = 1.5 should raise suspicion of hemodynamic compromise in high-risk populations. CONCLUSIONS: Pulse-oximetry is a commonly used tool for monitoring critically ill patients. The present study suggests that increased respiratory variability in the pulse-oximetry waveform should raise suspicion for hemodynamic compromise in patients at risk for pericardial effusion.

Acute Disease↗
PubMed1995

Intraoperative reflectance oximetry in burn patients.

OBJECTIVE: Transmission oximetry sites for intraoperative monitoring are frequently difficult to find in burn patients, as standard transmission oximetry sites are often burned or contained within the operative field. The objective of this study was to determine if reflectance oximetry is of potential value in monitoring this group of patients. METHODS: A total of 16 operative procedures in a group of acutely burned adult and pediatric patients with an average age of 9.7 years (range, 10 months to 37 years), average burn size of 42% of the body surface (range, 15% to 94%), and average weight of 34.2 kg (range, 9 to 100 kg) were done with simultaneous transmission and reflectance oximetry monitoring. RESULTS: During these 16 procedures in a diverse group of acutely burned adult and pediatric patients, there was no significant difference in saturations derived from transmission and reflectance oximetry probes. In smaller children, adequate signal for reflectance probe monitoring was often detected in hyperemic sites, such as healed partial thickness burn. CONCLUSIONS: This is the first published report documenting both the clinical use of the reflectance oximetry in burn patients and the clinical use of the Nellcor Oxisensor II RS-10 reflectance oximetry probe (Nellcor Corporation, Hayward, CA). This technique can facilitate the intraoperative monitoring of acutely burned adult and pediatric patients in whom standard transmission oximetry sites are difficult to find.

Adult↗
PubMed1995

Exercise oximetry versus spirometry in the assessment of risk prior to lung resection.

BACKGROUND: Spirometry remains a standard method of assessing patient risk prior to lung resection despite its poor sensitivity and specificity. This study compares the relative ability of standardized exercise oximetry and spirometry--forced expiratory volume in the first second--to predict morbidity and mortality after lung resection. METHODS: The study comprised a retrospective review of 396 consecutive patients of whom 299 underwent both oximetry and spirometry. Oximetry was undertaken during standard exercise under the supervision of a single physical therapist. Spirometry identified 46 patients with a forced expiratory volume in the first second of less than 1.5 L who were considered to be high risk. Exercise oximetry was used to identify patients with arterial oxygen desaturation at rest, while walking on level ground, or while climbing two flights of stairs (n = 65). RESULTS: Compared with spirometry, exercise oximetry more reliably predicted home oxygen requirements (p < 0.001), need of admission to the intensive care unit (p < 0.05), prolonged hospital stay (p < 0.001), and respiratory failure (p < 0.05). Oximetry identified 50% of the patients who died, all of whom had a forced expiratory volume in the first second of greater than 1.5 L. Despite its superior predictive value, the sensitivity of oximetry remained low. CONCLUSIONS: We conclude that standardized exercise oximetry is a superior screen of the high-risk patient than spirometry (forced expiratory volume in the first second) prior to pulmonary resection when there are no other risk factors noted on initial history and physical examination. A prospective, randomized trial is required to substantiate this conclusion.

Critical Care↗
PubMed1996

Evaluation of pulse oximetry in sickle cell anemia patients presenting to the emergency department in acute vasoocclusive crisis.

This prospective study was done to evaluate the accuracy of pulse oximetry as an indicator of hypoxemia in sickle cell anemia patients presenting to the ED in acute vasoocclusive crisis. Thirteen patients (age older than 18 years) presenting in crisis, with pulse oximetry readings less than 95% had arterial blood gas (ABG) analysis performed. The mean pulse oximetry reading was 91.4% +/- 3.2% (SD); the mean ABG oxygen saturation (ABG O2 sat) was 95.3% +/- 1.4% (SD). The mean O2 sat difference (ABG O2 sat minus pulse oximetry) was 4.5% (P < .001 versus a control group of ED patients receiving ABG and pulse oximetry). Pulse oximetry correlated with ABG O2 sat (r = 0.889, P < .001) and O2 sat difference (r = -0.927, P < .001). No correlation existed between complete blood count, reticulocyte count, historical and physical examination findings, and O2 sat or O2 sat difference. By linear regression, ABG O2 sat = 0.44 (pulse oximetry) + 55.6. This study suggests that pulse oximetry underestimates oxygenation in sickle cell anemia patients presenting in painful crisis.

Acute Disease↗
PubMed2002

Accuracy of fetal pulse oximetry.

BACKGROUND: The goal of this investigation was to evaluate the agreement of fetal pulse oximetry to saturation readings from hemoximetry at low oxygen saturation. METHODS: Fetal oxygen saturation measurements obtained by pulse oximetry were compared with those obtained by hemoximetry in fetal scalp blood samplings. The prospective observational trial included fetuses with non-reassuring fetal heart rate tracings suggestive of hypoxia and requiring fetal scalp blood samplings. Arterial oxygen saturation was determined by a blinded pulse oximeter (N400, FS14; Nellcor Puritan Bennett, Pleasanton, CA, USA) and continuously stored on a notebook computer. Saturation from fetal scalp blood samples was measured by hemoximetry (Bayer Diagnostics 865; ABL 625, Radiometer). Data analysis focussed on the absolute and relative difference between hemoximetry and pulse oximetry of fetuses, showing the most distinct difference in neonatal outcome. Normal outcome was defined as spontaneous delivery and umbilical artery pH >or= 7.20 + Apgar 5 >or= 7 (n = 42). In contrast, a group of neonates with combined respiratory and metabolic acidemia at birth was defined by pH <or= 7.16 and an additional base excess <or= -9.4 mmol/l in the umbilical artery (n = 18). RESULTS: The correlation coefficient between hemoximetry and pulse oximetry measurements was r = 0.72; p = 0.002 in the acidemic group. The median of absolute differences in saturation was + 5.2% (95%CI 2.5-10.3) saturation. The absolute differences ranged from -21% to + 36% saturation. The median of relative differences amounted to 23% (95%CI 15.1-55.0). The relative differences ranged from -30% to + 217%. Observing the saturation distribution in the two groups (hemoximetry and pulse oximetry, respectively) presented a median hemoximetry pulse oximetry of 38% (42%) in the normal and 26% (39%) in the acidemic group. In this small group of cases, the correlation coefficient between pH and saturation from pulse oximetry in fetal scalp blood from the samplings was r = 0.19. CONCLUSION: Fetal pulse oximetry tends to overestimate arterial oxygen saturation compared with hemoximeter values.

Adult↗
PubMed2003

Combined index of heart rate variability and oximetry in screening for the sleep apnoea/hypopnoea syndrome.

Many sleep centres employ a preliminary screening test in order to reduce the number of polysomnographies required in the routine diagnosis of the sleep apnoea/hypopnoea syndrome (SAHS). We investigated the combination of heart rate and oximetry information as a means of performing this test. A retrospective study of 100 patients with suspected SAHS was made. All patients had in-hospital polysomnography on one night. We estimated the number of respiratory event-related arousals by counting the number of autonomic arousals (assessed on the basis of changes in the heart interbeat interval) that were coincident with a rise in oximetry. The hourly index of such events was denoted the "cardiac-oximetry disturbance index" (CODI). The median apnoea/hypopnoea index (AHI) was 16.5 (range 1.0-93.6) h-1. The CODI correlated significantly with the AHI (Spearman correlation coefficient rs = 0.88, P < 0.01), and the area (+/- standard error) under the receiver operating characteristic (ROC) was 0.94 +/- 0.05. Oximetry alone (based on 4% dips) was a less effective screening test (rs = 0.80, P < 0.01; area under ROC 0.83 +/- 0.06). Using 2% dips in oximetry offered comparable performance with the CODI (rs = 0.91, P < 0.01; area under ROC 0.93 +/- 0.04). The CODI was better correlated with the electroencephalograph arousal index (rs = 0.84, P < 0.01) than was oximetry (2% dips, rs = 0.57, P < 0.01). The CODI algorithm also offers an informal measure of self-validation: a large discrepancy between the number of autonomic arousals and the number of rises in oximetry indicates the presence of autonomic arousals without changes in oximetry (or vice versa). This self-validation mechanism identified several patients in this study, and may be useful in identifying sleep disruption due to chronic pain or other causes.

Adult↗
PubMed1998

Maternal perceptions of labor with fetal monitoring by pulse oximetry in a research setting.

OBJECTIVE: Little research has evaluated maternal experience with fetal pulse oximetry for fetal surveillance. The purpose of this study was to compare maternal perceptions of labor with intrapartal cardiotocography with or without fetal pulse oximetry in a research setting. METHODS: One hundred women with vaginal, vertex deliveries and uncomplicated fetal outcomes were enrolled. The study group was a subset of 50 mothers who had participated in a pulse oximetry trial. The control group of 50 mothers was monitored by cardiotocography only. Both groups were matched for age, parity, weeks of gestation, epidural anesthesia use, and duration of labor. A global measure of maternal perception of labor was established by experience with labor, general attitude toward monitoring devices, satisfaction with monitoring, nursing and medical care, and anxiety, each of which was evaluated separately. The mothers in the study group were also interviewed about aspects related to the fetal pulse oximetry research setting, such as information, movement restriction, discomfort, care, privacy, and safety. The questionnaires were based on a standardized rating scale model, and the interviews were conducted two to four days after delivery. The results were analyzed by chi-squared, paired t test, and ANOVA. RESULTS: No significant differences were observed between the study and control participants in any parameter concerning the maternal perception of labor. Mothers' experiences with pulse oximetry as assessed by interview was overwhelmingly positive. CONCLUSIONS: Fetal monitoring by pulse oximetry in a research setting did not affect maternal perceptions of labor. Mothers' experiences with pulse oximetry were highly positive, suggesting that research in fetal pulse oximetry need not compromise maternal perceptions of labor.

Adult↗
PubMed1987

Relationship of pulse oximetry to arterial oxygen tension in infants.

Pulse oximetry is a useful technique for noninvasive oxygen monitoring in sick infants. We simultaneously measured oxygen saturation by pulse oximetry and on arterial blood samples by co-oximetry as well as PaO2 and the relative content of fetal (F) and adult hemoglobin in order to evaluate the reliability of pulse oximetry. Comparisons were made in triplicate in ten infants with acute cardiorespiratory disease less than 7 days of age and in 11 infants with chronic lung disease greater than 28 days of age. Oxygen saturation pulse oximetry and arterial saturation were well correlated over a wide range of saturation values. In infants with chronic lung disease, PO2 derived from pulse oximetry was within 10 torr of measured PaO2 in 73% of comparisons. In contrast, calculated PaO2 was within 10 torr of measured PaO2 in only 50% of comparisons in patients with acute disorders. The chronic infants all had less than 10% hemoglobin F, but in the acute infants, hemoglobin F ranged from 26% to 83%. Nonetheless, correction of oxygen dissociation curves for type of hemoglobin in these acute infants failed to improve the correlation between calculated and measured PaO2. We conclude that pulse oximetry saturations and their derived PaO2 values correlated well with measured arterial saturation and PaO2 obtained from arterial blood samples in neonates with chronic lung disease and prolonged oxygen dependence. In infants with acute cardiorespiratory problems, pulse oximetry unreliably reflects PaO2, but may be useful in detecting clinical deterioration.

Evaluation Studies as Topic↗