Pulse Oximetry Recordings Research Articles

When to Suspect Sleep Apnea and What to Do About It

Obstructive sleep apnea (OSA), which is characterized by recurrent upper airway obstruction during sleep with resultant hypoxia-reoxygenation and sleep fragmentation, is prevalent among patients with cardiovascular disease. Refractory hypertension, nocturnal angina or arrhythmias, and stroke in particular should prompt consideration of OSA. The symptoms of OSA include snoring and excessive daytime sleepiness; risk factors include obesity and reduced upper airway dimensions. Up to 50% of patients with congestive heart failure (CHF) may manifest OSA, central sleep apnea-Cheyne-Stokes respiration (CSA-CSR), or both. Patients with CSA-CSR may present with fatigue, disrupted sleep, and paroxysmal nocturnal dyspnea. Objective sleep recording is required to document the nature and severity of sleep apnea. The gold standard is in-laboratory overnight polysomnography (PSG), including monitoring of electroencephalography and other signals to determine sleep-wake state, and recording of body position, airflow, respiratory effort, and pulse oximetry. Portable cardiorespiratory recorders are now approved for diagnosis in patients without comorbidities. Full PSG is recommended for diagnosis in all other cases, although OSA and CSA-CSR can be identified from portable recorders in some patients with CHF and other conditions. The objectives of treatment are to improve symptoms, quality of life, and cardiovascular outcomes. The mainstay of treatment for moderate-to-severe OSA is positive airway pressure (PAP). Automated PAP devices may be used in uncomplicated OSA, whereas continuous fixed PAP is the treatment of choice for other patients with OSA, and may also treat a proportion of patients with CSA-CSR. A form of bi-level PAP known as adaptive servoventilation is effective in treating a majority of patients with CSA-CSR.

Signal quality measures on pulse oximetry and blood pressure signals acquired from self-measurement in a home environment.

Recently, decision support system (DSSs) have become more widely accepted as a support tool for use with telehealth systems, helping clinicians to summarize and digest what would otherwise be an unmanageable volume of data. One of the pillars of a home telehealth system is the performance of unsupervised physiological self-measurement by patients in their own homes. Such measurements are prone to error and noise artifact, often due to poor measurement technique and ignorance of the measurement and transduction principles at work. These errors can degrade the quality of the recorded signals and ultimately degrade the performance of the DSS system, which is aiding the clinician in their management of the patient. Developed algorithms for automated quality assessment for pulse oximetry and blood pressure (BP) signals were tested retrospectively with data acquired from a trial that recorded signals in a home environment. The trial involved four aged subjects who performed pulse oximetry and BP measurements by themselves at their home for ten days, three times per day. This trial was set up to mimic the unsupervised physiological self-measurement as in a telehealth system. A manually annotated "gold standard" (GS) was used as the reference against which the developed algorithms were evaluated after analyzing the recordings. The assessment of pulse oximetry signals shows 95% of good sections and 67% of noisy sections were correctly detected by the developed algorithm, and a Cohen's Kappa coefficient (κ) of 0.58 was obtained in 120 pooled signals. The BP measurement evaluation demonstrates that 75% of the actual noisy sections were correctly classified in 120 pooled signals, with 97% and 91% of the signals correctly identified as worthy of attempting systolic and/or diastolic pressure estimation, respectively, with a mean error and standard deviation of 2.53±4.20 mmHg and 1.46±5.29 mmHg when compared to a manually annotated GS. These results demonstrate the feasibility, and highlight the potential benefit, of incorporating automated signal quality assessment algorithms for pulse oximetry and BP recording within a DSS for telehealth patient management.

Response from the authors to the letter "Pulse rate trends in obstructive sleep apnoea: a reliable tool to predict long term response to CPAP?".

To the editor, We appreciate the interest of Dr. Navarro-Esteva in our study (1). We are well aware of the contributions of previous studies within the field by Kufoy et al. (2) and Kawano et al. (3), which described the changes in physiological parameters but no symptomatic response to continuous positive airway pressure (CPAP) in patients with obstructive sleep apnoea (OSA). We believe we have explicitly acknowledged the methodological limitations of pulse oximetries pointed out by Dr. Navarro-Esteva in our paper. However, nocturnal pulse oximetries are easily available, often used in clinical settings and comply with evidence-based guidance to diagnose OSA (4). In addition, in a randomised controlled trial they were found to be non-inferior when compared to inpatient polysomnography (5). Obese patients with lower oxygen saturations are more likely to suffer not only from OSA but also from obesity hypoventilation syndrome (6). This can only be confirmed by nocturnal carbon dioxide measurements, a measurement that is not included in a standard polysomnography setup. Hence, we argue that the contention by Dr. Navarro-Esteva that “for research purposes, diagnosis should be confirmed by polygraphy or polysomnography” is hardly feasible in practice, as the best approach to diagnose OSA remains a controversial issue. The decision over which overnight investigation to employ is influenced by the available resources in the respective health care system. Moreover, in our study any decision to offer treatment was derived from evidence-based guidelines (4) and only 6 out of 58 (10%) patients with mild OSA were offered CPAP following physicians’ review. Dr. Navarro-Esteva is correct in stating that the symptom of hypersomnolence is of multi-factorial aetiological origin (7). Although OSA has got a high prevalence in the general population (8), hypersomnolence affects a larger group of people than those who suffer with sleep-disordered breathing. The main inclusion criteria in our study was a 4% oxygen desaturation index (ODI) greater than 5/h. We added the pulse rise index (PRI) as additional inclusion criteria for the control group to exclude patients with additional conditions which could lead to autonomic arousals from sleep and affect pulse rate variability. Zamarron et al. studied the approximate entropy (ApEn) analysis of heart rate data derived from nocturnal pulse oximetries in OSA. They concluded that ‘(…) the results presented prove that this method is very well suited to recognize the sleep-apnoea-specific cyclic variability of heart rate’. They also postulated that studying the heart rate signal was an effective tool to understand how brain, sleep and autonomic nervous system interact (9). As regards the definition of PR trend that left Dr. Navarro-Esteva uncertain, in the method section of our paper we have defined ‘PR trend’ as the difference between the average pulse rate of the first and the last hour of sleep. We hypothesised that an increase in ‘PR trend’ reflected an increased sympathetic activation throughout the night and that ‘PR trend’ could be a predictor of treatment success in a group of OSA patients treated with CPAP. In our study, there was no significant difference in CPAP compliance between groups. The observed trend towards a longer use in the group with a negative ‘PR trend’ is consistent with the clinical observation that patients who respond better to CPAP treatment are more likely to use it longer. Heart rate variability, pulse rate and the change in nocturnal pulse rate are important markers of autonomic nervous activity in OSA. Combined with the Epworth Sleepiness Scale (ESS), a patient-based symptoms score, and the response to CPAP therapy they are crucial markers to identify patients who are at an increased risk of cardiovascular events. In conclusion, our data support the usefulness of nocturnal pulse oximetry recordings in a clinical setting of a sleep centre. Although polysomnography remains the Gold-standard for the diagnosis of sleep disorders, nocturnal pulse oximetry has been shown to provide reliable results (10). Indeed, pulse oximetry data convey not only data on ventilation and oxygen saturation, but they also provide an insight into autonomic nervous activity at-a-glance with the potential to identify elevated cardiovascular risks. This finding is not negated by the aforementioned methodological limitations.

Accuracy of portable polygraphy for the diagnosis of sleep apnea in multiple system atrophy

ObjectiveTo assess the diagnostic accuracy of portable polygraphy (PG) for the detection of sleep apnea (SA) in multiple system atrophy (MSA). MethodsThirty consecutive patients with probable MSA underwent PG (overnight recording of nasal flow, thoracic/abdominal movements and pulse oximetry), followed 4weeks later by full polysomnography (PSG) (reference standard). The accuracy of PG was first assessed using the same threshold as for PSG (apnea–hypopnea index [AHI]⩾5), then for all possible AHI thresholds using the area under the receiver operating characteristics (AUROC) curve. Inter-rater reliability of PG was assessed using the kappa coefficient. ResultsAmong 30 patients enrolled, seven were excluded for technical problems on PG or PSG and 23 were included in the main analysis. Eight out of 23 had an AHI⩾5 on PSG. With the same threshold, sensitivity, specificity, positive and negative predictive values of PG for the diagnosis of SA were 87.5% (95% confidence interval: 47–99), 80% (52–96), 70% (35–93) and 92.3% (64–99), respectively. The kappa between PG raters was 0.75 (0.49–1.00) indicating good agreement. The AUROC was 0.93 (0.82–1.00). No association was found between sleep and excessive daytime sleepiness questionnaires and SA. ConclusionPortable PG seems to be valuable for ruling out SA in MSA.

Peripheral perfusion index measured using magnetohydrodynamic voltages in 3T MRI

Background The Peripheral Perfusion Index (PFI) has been utilized for early detection of impaired organ perfusion in order to avoid tissue hypoxia, which could lead to organ failure [1]. A decrease in effective circulating blood volume, lowering of PFI levels, can cause vasoconstriction [2]. Strong MRI magnetic field (B0) interactions with flowing blood plasma electrolytes produce a Magnetohydrodynamic voltage (VMHD) [3]. We hypothesized that a processing method which derives VMHD at different segments of the body could provide a direct indicator for PFI as well as local perfusion levels in various body regions. Existing methods for PFI estimation include Pulse Oximetry (PO) and differential temperature recordings, both of which are indirect measurements [4].

Pulse oximetry recording in children with adenotonsillar hypertrophy: usefulness in the diagnostic of obstructive sleep apnea syndrome

Pulse oximetry recording in children with adenotonsillar hypertrophy: usefulness in the diagnostic of obstructive sleep apnea syndrome

Night‐to‐night consistency of at‐home nocturnal pulse oximetry testing for obstructive sleep apnea in children

At-home nocturnal pulse oximetry has a high positive predictive value (PPV) for polysomnographically-diagnosed obstructive sleep apnea (OSA) but no studies have been published testing the night-to-night consistency of at-home nocturnal pulse oximetry for the evaluation of suspected OSA in children. We therefore determined the night-to-night consistency of nocturnal pulse oximetry as a diagnostic test for OSA in children. We prospectively studied 148 children (96 male) aged 4.9 ± 2.4 (1.2-11.8) years, referred for suspected OSA. To evaluate night-to-night consistency, we compared an oximetry analysis method, the McGill Oximetry Score (MOS), from two consecutive at-home nocturnal pulse oximetry recordings. Pulse oximetry metrics were similar on the two nights. The MOS on the two nights showed excellent night-to-night consistency when analyzed as positive for OSA versus inconclusive, 143/148 (Spearman's correlation coefficient = 0.90). A more detailed analysis using four categories (MOS 1, 2, 3, and 4) of OSA severity showed very good night-to-night agreement, 133/148 (Spearman's correlation coefficient = 0.91). Variability was increased in children younger than 4 years of age compared to older children. Night-to-night consistency of nocturnal pulse oximetry as a diagnostic test for OSA showed excellent agreement. Night-to-night consistency of pulse oximetry, as analyzed by the MOS, for diagnosis and severity evaluation further validates this abbreviated testing method for pediatric OSA. Polysomnography (PSG) is required to rule in or rule out OSA in children if a single night oximetry testing is inconclusive.

Comparing methods of respiratory event detection during the treatment of obstructive sleep apnea

Renewed focus on comparative effectiveness research presents a unique opportunity to develop optimal clinical management pathways for patients with obstructive sleep apnea. With this momentum comes the challenge of measuring treatment effect on sleep-disordered breathing, especially in large, multisite studies. In-laboratory polysomnography, the current gold standard sleep assessment of obstructive sleep apnea severity, is costly and imposes significant participant burden. Alternatives include home unattended sleep testing and overnight pulse oximetry recording. Research studies using positive airway pressure treatment have the additional option of using the information recorded by the patient's positive airway pressure device to assess treatment effectiveness. Recent research has shown relatively good agreement between manual identification of residual respiratory events in overnight in-laboratory polysomnography and the automatic event detection utilized in positive airway pressure machines. In addition to assessing the effects of interventions on sleep disordered breathing, obstructive sleep apnea-related comparative effectiveness studies need to assess the impact of the interventions on patient burden, cost of therapy, timeliness of care, improved quality of life and other clinically relevant outcomes.

Sleep quality and nocturnal hypoxaemia and hypercapnia in children and young adults with cystic fibrosis

ObjectivesThe aim of the study was to evaluate sleep quality and nocturnal gas exchange in patients with cystic fibrosis (CF) and to assess if sleep quality and daytime lung function...

Determining presence of lung disease in young children with cystic fibrosis: Lung clearance index, oxygen saturation and cough frequency

BackgroundAccurate assessment of pulmonary status in young children with cystic fibrosis (CF) requires sensitive and objective monitoring techniques. ObjectivesThis study aimed to evaluate the feasibility of lung clearance index (LCI) calculated from multiple breath washout (MBW), home nocturnal pulse oximetry and home nocturnal cough recording in young children with CF, and determine whether these tests can distinguish CF patients from healthy controls. MethodsWe performed a prospective cross-sectional study in 20 CF patients and 30 healthy children aged 0–4years. MBW was performed in awake and unsedated children at the outpatient clinic using a commercially available device. Measurements of nocturnal oxygen saturation and nocturnal cough were done at home using a pulse oximeter and an audiometer. ResultsThere was a significant difference in mean LCI between healthy children and CF patients (LCI 7.1 vs. 9.3, p<0.001). Nocturnal oxygen saturation was normal in both groups and did not significantly differ between the groups. Similarly, cough showed no differences between both groups. Cough varied widely between children and between nights. Success rates for saturation and cough measurements were 90% and were similar for CF patients and healthy children. Success rate for LCI was 75% for CF patients and 50% for healthy children. ConclusionsMeasurements of LCI, nocturnal oxygen saturation and cough were feasible in young children; however LCI was the only variable that showed a significant difference between children with CF and healthy children.

Reference values for pulse oximetry recordings in healthy term neonates during their first 5 days of life

ObjectiveTo determine reference values for pulse oximeter saturation (SpO2) variables and desaturation event indices in healthy term neonates during their first 5 days of life, and to compare two definitions...

Polisomnografía y otros métodos de registro

Additional tests are needed for an accurate diagnosis of most sleep disorders in children. Of these additional tests, especially when study of sleep breathing disorders in children is required, complete overnight polysomnography is currently considered the gold standard for the diagnosis of sleep disorders. There are, however, other simplified tests, although less informative and reliable, which may be acceptable diagnostic alternatives, such as respiratory polygraphy and pulse oximetry recording. This article will explain the main indications, methodology and advantages and disadvantages of the various sleep tests.

Arterial and Plethysmographic Waveform Analysis in Anesthetized Patients with Hypovolemia

Respiratory-induced arterial and plethysmographic (pulse oximetry) waveform changes were shown to be good predictors of cardiac output response to increased preload. The aim of this study was to evaluate the reliability of arterial and plethysmographic waveform variables in patients with mild hypovolemia. Patients undergoing autologous hemodilution were studied. After anesthesia induction, hemodilution was performed by withdrawing blood in steps of 2% of estimated circulating blood volume (ECBV), up to 20%. The patients who did not develop hypotension (systolic blood pressure < 80 mmHg) were studied. Arterial and plethysmographic waveforms were recorded and analyzed off-line at baseline and after each withdrawal of blood. Variations in arterial systolic and pulse pressure were analyzed using standard methods. Plethysmographic waveform variation and delta pulse oximetry plethysmography were determined by using pulse oximetry recordings. There were 33 study participants. Systolic blood pressure decreased by 11%, and heart rate increased from 73 to 76 beats/min after a 20% reduction of ECBV. Systolic pressure and pulse pressure variations increased (P < 0.005) after a 4% reduction of ECBV. The values of arterial pressure and pulse oximetry waveform variables almost doubled in value after a 20% reduction of ECBV. Systolic pressure variation was the most reliable variable during hypovolemia. Plethysmographic waveform variation increased significantly after a 6% reduction of ECBV and delta pulse oximetry plethysmography after an 8% reduction of ECBV. Arterial and pulse oximetry respiratory-induced changes in waveform variables are reliable indicators of mild hypovolemia in anesthetized patients. The pulse oximetry plethysmographic waveforms accurately reflect arterial waveforms during more progressive hypovolemia.

Telemedicine to support end of life in severe chronic respiratory failure patients at home

Tele hospice has been demonstrated useful and cost saving for palliative care. The aim of the present study was to analyze the feasibility of impact of a telemedicine (TM) programme on severe chronic respiratory failure (CRF) patients discharged to home, their family and the healthcare team (HCT) in the terminal phase of life. TM consisted of scheduled phone calls, pulse-oximetry recording, 24h call centre, and specialised nurse and physician second opinion. 21 patients out of 118 died after 6±3.4 months of follow up. Compared to the 97 surviving subjects, the deceased patients presented a higher number of hospitalisations/month (0.36±0.33 vs. 0.09±0.14 p<0.005), ER visits/month (0.31±0.40 vs. 0.02±0.04 p<0.005), exacerbations/month (0.39±0.42 vs. 0.11±018 p<0.003) and urgent calls/month to the GP (0.22±0.34 vs. 0.19±0.05 p<0.02). The TM team was involved in counselling on hospital admissions, discussions and decisions reached in consensus, all care options to avoid a nihilistic position or aggressive and disproportional care choices, GP or home nurse consultations, sedative or morphine prescription, resolving problems with ventilators, the prescription of oxygen saturation monitoring, patient education regarding the severity of the illness, coordination with home nursing services and psychological and spiritual help. A nurse-centred TM programme for terminal patients may: (1) improve communication between hospital staff and the patients’ relatives; (2) optimise the management of pain and respiratory symptoms; (3) improve health care assistance; and (4) rationalise hospitalisations and the health care needs.

Preliminary results from a telemedicine referral network for early diagnosis of sleep apnoea in sleep laboratories

We conducted a feasibility study to find out whether a simple preliminary examination using telemedicine for diagnosis was sufficient to identify sleep-related breathing disorders (SRBD). Night-time pulse oximetry recordings were made in normal home surroundings on patients suffering from sleep apnoea/SRBD by doctors with a range of non-specialist backgrounds. The readings were transmitted to the relevant sleep laboratory, examined and the results returned to the referring doctor. From 80 patients (aged 29 to 60 years), 58 complained about characteristic symptoms (snoring, daytime sleepiness); 33 of these patients showed additional symptoms of associated diseases. In eight patients associated diseases were found without any symptoms. The findings were compatible with SRBD in 58 cases (73%); 12 of these were asymptomatic patients. A total of 57 patients had to be referred to a sleep laboratory for differential diagnosis by full polysomnography. Of the 22 patients (28%) without pathological findings following pulse-oximetry, 12 were symptomatic. The system described here is suitable for the creation of referral networks and for the identification of patients from institutions not trained in sleep medicine, who would otherwise not have been referred for specific diagnosis to a sleep laboratory.

Identification of Patients at Risk for Postoperative Respiratory Complications Using a Preoperative Obstructive Sleep Apnea Screening Tool and Postanesthesia Care Assessment

Patients with obstructive sleep apnea are at risk for perioperative morbidity. The authors used a screening prediction model for obstructive sleep apnea to generate a sleep apnea clinical score (SACS) that identified patients at high or low risk for obstructive sleep apnea. This was combined with postanesthesia care unit (PACU) monitoring with the aim of identifying patients at high risk of postoperative oxygen desaturation and respiratory complications. In this prospective cohort study, surgical patients with a hospital stay longer than 48 h who consented were enrolled. The SACS (high or low risk) was calculated; all patients were monitored in the PACU for recurrent episodes of bradypnea, apnea, desaturations, and pain-sedation mismatch. All patients underwent pulse oximetry postoperatively; complications were documented. Chi-square, two-sample t test, and logistic regression were used for analysis. The oxygen desaturation index (number of desaturations per hour) was calculated. Oxygen desaturation index and incidence of postoperative cardiorespiratory complications were primary endpoints. Six hundred ninety-three patients were enrolled. From multivariable logistic regression analysis, the likelihood of a postoperative oxygen desaturation index greater than 10 was increased with a high SACS (odds ratio = 1.9, P < 0.001) and recurrent PACU events (odds ratio = 1.5, P = 0.036). Postoperative respiratory events were also associated with a high SACS (odds ratio = 3.5, P < 0.001) and recurrent PACU events (odds ratio = 21.0, P < 0.001). Combination of an obstructive sleep apnea screening tool preoperatively (SACS) and recurrent PACU respiratory events was associated with a higher oxygen desaturation index and postoperative respiratory complications. A two-phase process to identify patients at higher risk for perioperative respiratory desaturations and complications may be useful to stratify and manage surgical patients postoperatively.

Effects of hyperbaric oxygen on the replanted extremity subjected to prolonged warm ischaemia

In this investigation, the influence of hyperbaric oxygen (HBO) therapy on the survival of a replanted extremity subjected to prolonged warm ischaemia is evaluated. Among the relative contraindications to replantation are prolonged warm ischaemia time, since an obstruction to blood reflow ('no-reflow phenomenon') may occur in amputated parts that are subjected to more than 6h of warm ischaemia. Twenty-three rat hindlimbs were amputated and subjected to 4h of normothermic ischaemia. The average weight of the animals was 500 gm, and re-plantation of the hindlimb was performed by bone fixation followed by microvascular anastomosis of the femoral vessels. Limb re-vascularisation was confirmed at the end of all procedures by the milk test, clinical assessment and pulse oximetry recordings (>90%). Eleven animals served as a control group and no further therapy was instituted, whereas 12 animals served as the study (replantation) group and were subjected to HBO therapy for 3 days postoperatively. The therapy was conducted in a large animal chamber for 90 min at 2.5 ata. Limb survival was assessed by capillary refill upon compression, skin turgor assessment and colour. Confirmation of clinical findings was conducted with daily pulse oximetry readings of >90%. Animals were followed up for 7 days at which point all animals were euthanized or were euthanized earlier if a non-viable limb was present. Two of the 11 limbs in the control group survived following re-plantation, whereas eight of the 12 limbs in the experimental HBO group survived at least 7 days following replantation. This difference was statistically significant (p=0.0361) using chi-square analysis and Fisher's exact test. Although re-plantation of an amputated extremity after prolonged warm ischaemia is considered a relative contraindication due to the possibility of poor outcomes, our results indicate that the window for replantation may be increased if adjunctive HBO therapy is employed in the postoperative period.

Carbon dioxide monitoring during long-term noninvasive respiratory support in children

Routine monitoring of noninvasive respiratory support relies on nocturnal pulse oximetry and daytime arterial blood gases, without systematic nocturnal carbon dioxide recording. The aim of the study was to assess if overnight pulse oximetry and daytime blood gases are sufficiently accurate to detect nocturnal hypoventilation in children receiving long-term noninvasive respiratory support. Pulse oximetry and carbon dioxide pressure measured by capillary arterialized blood gases and a combined transcutaneous carbon dioxide and pulse oximetry (PtcCO(2)/SpO(2)) monitor were compared in 65 patients (asthma, n = 16, recurrent bronchitis, n = 8, lung infection, n = 8, cystic fibrosis, n = 15, interstitial lung disease, n = 6, neuromuscular disease, n = 12). Daytime capillary arterialized blood gases and nocturnal recording of pulse oximetry and carbon dioxide by means of a combined PtcCO(2)/SpO(2) monitor were performed in 50 other patients receiving nocturnal noninvasive respiratory support at home. A correlation was observed between pulse oximetry (r = 0.832, P < 0.0001) and carbon dioxide pressure (r = 0.644, P < 0.0001) measured by capillary arterialized blood gases and the combined PtcCO(2)/SpO(2) monitor. Twenty-one of the 50 patients (42%) on long-term noninvasive respiratory support presented nocturnal hypercapnia, defined by a PtcCO(2) value >50 mmHg, without nocturnal hypoxemia. Daytime capillary arterialized carbon dioxide levels were normal in 18 of these 21 patients. Nocturnal hypercapnia may occur in children receiving nocturnal noninvasive respiratory support at home. Nocturnal pulse oximetry and daytime arterial blood gases are not sufficiently accurate to diagnose nocturnal hypercapnia, underlying the importance of a systematic carbon dioxide monitoring in children receiving noninvasive respiratory support.

Preoperative Brain Injury in Transposition of the Great Arteries Is Associated With Oxygenation and Time to Surgery, Not Balloon Atrial Septostomy

Preoperative brain injury is an increasingly recognized phenomenon in neonates with complex congenital heart disease. Recently, reports have been published that associate preoperative brain injury in neonates with transposition of the great arteries with the performance of balloon atrial septostomy (BAS), a procedure that improves systemic oxygenation preoperatively. It is unclear whether BAS is the cause of brain injury or is a confounder, because neonates who require BAS are typically more hypoxemic. We sought to determine the relationship between preoperative brain injury in neonates with transposition of the great arteries and the performance of BAS. We hypothesized that brain injury results from hypoxic injury, not from the BAS itself. Infants with transposition of the great arteries (n=26) were retrospectively included from a larger cohort of infants with congenital heart disease who underwent preoperative brain MRI as part of 2 separate prospective studies. Data collected included all preoperative pulse oximetry recordings, all values from preoperative arterial blood gas measurements, and BAS procedure data. MRI scans were performed on the day of surgery, before the surgical repair. Of the 26 neonates, 14 underwent BAS. No stroke was seen in the entire cohort, whereas 10 (38%) of 26 patients were found to have hypoxic brain injury in the form of periventricular leukomalacia. Periventricular leukomalacia was not associated with BAS; however, neonates with periventricular leukomalacia had lower preoperative oxygenation (P=0.026) and a longer time to surgery (P=0.028) than those without periventricular leukomalacia. Preoperative brain injury in neonates with transposition of the great arteries is associated with hypoxemia and longer time to surgery. We found no association between BAS and brain injury.

Fetal pulse oximetry: Correlation with intrapartum fetal heart rate patterns and neonatal outcome

To determine how fetal pulse oximetry behaves in various cardiotocographic (CTG) tracings and correlates with neonatal outcome. Pregnant women undergoing active labor with singleton pregnancies of 32-42 weeks were enrolled. CTG recordings were reassuring or nonreassuring (namely variable or persisting late decelerations). Pulse oximetry values during labor and changing throughout deceleration and recovery phases, duration and frequency of pulse oximetry recordings <30%, and neonatal outcome were determined. One-way anova, Tukey test, chi(2)-test and multiple logistic regression model were used for statistical analysis where appropriate. A total of 156 pregnant subjects were divided into three groups: reassuring fetal heart rate (FHR) patterns (group 1, n=78 [50%]), late decelerations (group 2, n=16 [10.3%]) and variable decelerations (group 3, n=62 [39.7%]). The initial and final pulse oximetry readings, pulse values in first stage of labor, the duration and the frequency of pulse oximetry recordings <30% were significantly different between groups (P<0.001, P<0.001, P<0.001, P=0.001, P<0.001). Fetal acidosis was significantly more frequent with late decelerations (23.1%, P=0.004). A multiple logistic regression model demonstrated that the initial pulse oximetry value during active labor was the most predictive variable of neonatal well-being (P<0.001). Decreased fetal pulse oximetry values, especially prolonged and recurrent recordings <30% are well-correlated with abnormal FHR patterns, indicating an association with fetal compromise and metabolic acidosis. Going through active labor with a lower initial value of FSpO(2) more frequently leads to an altered FHR pattern and subsequent adverse fetal outcome.