Pulse oximetry in preterm infants (original) (raw)
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Effect of fetal haemoglobin on the accuracy of pulse oximetry in preterm infants
Journal of Paediatrics and Child Health, 1992
Pulse oximeters are programmed with a calibration curve derived from studies done in adults. Whether fetal haemoglobin levels affect their reliability is unclear. This study reports the accuracy of pulse oximetry in 22 preterm infants (mean 31 weeks, range 25-36 weeks gestation) between 1 h and 73 days of age. Oxygen saturation obtained from a Nellcor N-200 pulse oximeter (SpO2) was compared with simultaneous arterial values (functional SaO2) measured by a Radiometer OSM3 Hemoximeter over a SpO2 range of 83-99%. Fetal haemoglobin (HbF), carboxyhaemoglobin (HbCO) and methaemoglobin (HbMet) measured by the hemoximeter ranged between 0-100%, 0-3.5% and 0-0.8% respectively. Linear regression analysis revealed a close correlation between SpO2 and functional SaO2 (SpO2 = 0.75 SaO2 + 24.43, r = 0.88, P less than 0.001) over a wide range of values for PCV, heart rate, blood pressure, PaO2, PaCO2 and pH. The mean SpO2-SaO2 difference of 1.3, (s.d. 2.5%, P less than 0.001) was unaffected by HgF, HbCO or HbMet but was increased in infants receiving inotropic support. We conclude that the Nellcor N-200 pulse oximeter gives reliable oxygen saturation measurements unaffected by the HbF level in preterm infants.
From oxygen content to pulse oximetry: Completing the picture in the newborn
Acta Anaesthesiologica Scandinavica, 1995
In recent years clinicians caring for sick preterm infants have come to depend on pulse oximetry to avoid hyperoxia, which means assuming saturation values for critical levels of oxygen tension. This prediction is made difficult by the shape of the haemoglobin-oxygen dissociation curve at critical values for arterial PO, and by the effects of changes in acid-base balance on p50. Combined blood gas and co-oximetry measurements can be used to determine critical limits for pulse oximetry. Fetal haemoglobin has slightly different light absorption characteristics from adult haemoglobin. To adjust for this, adult and fetal matrices are available in the OSMTM3 HEMOXIMETERTM (Radiometer Medical A/& Denmark) but the measurement requires an extra preliminary step to estimate fetal haemoglobin concentration. We sought to determine the importance of this extra procedure for measuring the saturation of newborn blood, and to determine whether the adult or fetal mode should be used for determining saturation for comparison with pulse oximeters. We measured the effect of the correction for fetal haemoglobin by obtaining absorbances from the co-oximeter and multiplying them by the adult and fetal matrices. We demonstrated that, at 90% saturation, failure to use the fetal correction in the presence of high levels of fetal haemoglobin result in a 4% overestimate of saturation, with resultant underestimation of the safe range for pulse oximetry. Published values for extinction coefficients for fetal and adult blood at wavelengths used by pulse oximeters are inconsistent, but it appears that fetal haemoglobin does not bias pulse oximetry readings. Determining saturation limits by co-oximetry for use with pulse oximeters in preterm infants requires the description of the haemoglobin-oxygen dissociation curve with the correction for fetal haemoglobin.
2016
Background Arterial blood gas is usually beneficial to discern the nature of gas exchange disturbances, the effectiveness of com- pensation, and is required for adequate management. Although PaO 2 is the standard measurement of blood oxygenation, oxygen saturation measured by pulse oximetry (SapO 2 ) is now a custom- ary noninvasive assessment of blood oxygenation in newborn in- fants. Objective To compare oxygen saturation measured by pulse oxi- metry (SapO 2 ) and arterial blood gas (SaO 2 ), its correlation with other variables, and to predict arterial partial pressure of oxygen (PaO 2 ) based on SapO 2 values. Methods A cross sectional study was conducted on all neonates admitted to Pediatric Intensive Care Unit (PICU) during February 2001 to May 2002. Neonates were excluded if they had impaired peripheral perfusion and/or congenital heart defects. Paired t-test was used to compare SapO 2 with SaO 2 . Correlation between two quantitative data was performed using Pearson’s correl...
Longitudinal pilot study of oxygen saturation indices in healthy preterm infants
Pediatric Research
Background This study aimed to determine patterns of nocturnal pulse oximetry indices in moderate to late preterm infants, and investigate the relationship between oxygen desaturations, the apnoea hypopnoea index, and both corrected gestational and postnatal age. Methods 21 healthy infants born at 32 + 0 - 36 + 6 weeks gestation underwent serial nocturnal pulse oximetry studies and respiratory polygraphy studies until 40 weeks corrected gestational age (CGA). The main outcome measures were number of >3% oxygen desaturations/hour (ODI3), mean oxygen saturations, and number of apnoeas and hypopnoeas/hour. Results Median ODI3 increased between weeks 1 and 3 from 49.9 to 85.4/hour (p = 0.017). Mean oxygen saturations reached a corresponding nadir of 96.0% in week 3, then increased to 96.8% in week 6 (p = 0.019). Mixed effects modelling demonstrated that ODI3 and mean saturations were influenced by postnatal age but not CGA (p < 0.05). Desaturations frequently occurred without an a...
Directly measured arterial oxygen saturation in the newborn infant
An understanding of oxygen transport is fundamental to the management of the critically ill neonate, because at no other time in life is the oxyhemoglobin dissociation curve in such a state of flux? Current practice relies almost exclusively on oxygen tension as an index of oxygenation, but oxygen content and saturation and the affinity of hemoglobin for oxygen are also important in tissue oxygen delivery. ' We directly measure arterial oxygen hemoglobin saturation with a co-oximeter and calculate P503 (the Po2 at which the blood is 50% saturated) as a guide in the management of oxygen therapy. With this information we establish daily limits for the transcutaneous Po2 monitors in order to maintain HbO2% between 80% and 90%. We were impressed with the high carboxyhemoglobin levels recorded by the co-oximeter, but found that this is a feature of the instrument in the presence of fetal hemoglobin. +,5 This study was undertaken to test the hypothesis that the measured HbCO% is related to the HbF%; we postulated that it could provide an indirect but simple method of determining HbF concentration.
Pulse Oximeter with Longer Averaging Time and Missed Chronic Hypoxia in Preterm Infants
Journal of Nature and Science of Medicine, 2021
Background: Targeted oxygen saturation in preterm infants has been an area of debate for decades. Mild chronic hypoxia exposes some infants to significant comorbidities like pulmonary artery hypertension (PAH). The pulse oximeters vary in technical properties and setting; pulse oximeters with shorter SpO2 averaging time may provide a more accurate oxygen assessment. Aim: To evaluate the readiness of preterm infants for discharge based on the current unit’s protocol which uses standard pulse oximetry with an averaging time of 20s, as opposed to a pulse oximeter with a shorter averaging time (2s). Methods: The study was a prospective observational pilot study included all infants <32 weeks’ postmenstrual age (PMA) with no cardiovascular or respiratory pathology other than related to prematurity, such as bronchopulmonary dysplasia (BPD) and persistent ductus arteriosus. All infants underwent Echocardiography studies after the 2nd week of life and after 36 weeks to exclude PAH. All infants older than 36 weeks PMA who were off oxygen and ready to be discharged home as per unit’s protocol underwent final oxygen assessment for a minimum of 6 h using motion resistant oximeter with a SpO2 short averaging time of 2s. Results: Thirty‑five infants underwent the oxygen pulse oximetry testing. Of them, 42% were found to have chronic hypoxia (defined as 5% of recorded time with SpO2 ≤ 90%) and fulfilled the diagnostic criteria for BPD. Conclusions: A significant number of infants at 36 weeks’ PMA with chronic hypoxia were missed using the current unit’s oxygen assessment. With the prevalence being higher in infants diagnosed with BPD, a future study must be conducted to investigate the correlation between missed chronic hypoxia in infants with BPD and late‑onset PAH.
Factors Affecting the Target Oxygen Saturation in the First Minutes of Life in Preterm Infants
Journal of tropical pediatrics, 2016
The aim of this study was to describe the effect of factors on time to reach a pulse oxygen saturation (SpO2) level of 90% in preterm infants in the delivery room. Preterm (<35 gestational age) infants who did not require supplemental oxygen were included in the study. Continuous recordings were taken by pulse oximetry during the first 15 min of life. Of 151 preterm infants, 79 (52.3%) were female and 126 (83.5%) were delivered by cesarean section. Target saturation level (≥90%) was achieved faster in preductal measurements. Mean times taken to have a preductal and postductal SpO2 level of 90% were significantly lower in preterm babies born by vaginal delivery, with umbilical arterial pH ≥ 7.20 and whose mothers were non-smokers during pregnancy. Differences in achievement of target saturation level were influenced by multiple factors (birth way, probe location, maternal smoking and umbilical blood gas pH) in the delivery room during resuscitation of preterm babies.
Oxygen saturation and outcomes in preterm infants
2013
Background: The clinically appropriate range for oxygen saturation in preterm infants is unknown. Previous studies have shown that infants had reduced rates of retinopathy of prematurity when lower targets of oxygen saturation were used. Methods: In three international randomized, controlled trials, we evaluated the effects of targeting an oxygen saturation of 85 to 89%, as compared with a range of 91 to 95%, on disability-free survival at 2 years in infants born before 28 weeks' gestation. Halfway through the trials, the oximeter-calibration algorithm was revised. Recruitment was stopped early when an interim analysis showed an increased rate of death at 36 weeks in the group with a lower oxygen saturation. We analyzed pooled data from patients and now report hospital-discharge outcomes. Results: A total of 2448 infants were recruited. Among the 1187 infants whose treatment used the revised oximeter-calibration algorithm, the rate of death was significantly higher in the lower-target group than in the higher-target group (23.1% vs. 15.9%; relative risk in the lower-target group, 1.45; 95% confidence interval [CI], 1.15 to 1.84; P=0.002). There was heterogeneity for mortality between the original algorithm and the revised algorithm (P=0.006) but not for other outcomes. In all 2448 infants, those in the lower-target group for oxygen saturation had a reduced rate of retinopathy of prematurity (10.6% vs. 13.5%; relative risk, 0.79; 95% CI, 0.63 to 1.00; P=0.045) and an increased rate of necrotizing enterocolitis (10.4% vs. 8.0%; relative risk, 1.31; 95% CI, 1.02 to 1.68; P=0.04). There were no significant between-group differences in rates of other outcomes or adverse events. Conclusions: Targeting an oxygen saturation below 90% with the use of current oximeters in extremely preterm infants was associated with an increased risk of death. (Funded by the Australian National Health and Medical Research Council and others; BOOST II Current Controlled Trials number, ISRCTN00842661, and Australian New Zealand Clinical Trials Registry numbers, ACTRN12605000055606 and ACTRN12605000253606.).