Detection of Pulsus Paradoxus by Pulse Oximetry in Pediatric Patients After Cardiac Surgery

The presence or absence of pulsus paradoxus (PP), defined as an inspiratory decrease greater than 10 mmHg in systolic blood pressure, can have significant diagnostic and therapeutic implications for many clinical conditions including acute asthma, pericardial tamponade, heart failure, hypovolemia, shock states, and the like. However, PP may be difficult to measure in children. Indwelling arterial catheters facilitate the measurement of PP, but this invasive technique generally is reserved for critically ill patients. This study aimed to assess the use of the pulse oximetry plethysmographic waveform (POPW) for the detection of PP in pediatric patients after cardiac surgery. The study enrolled 40 pediatric patients 18 years of age and younger who had invasive blood pressure monitoring with an intraarterial cannula. Systolic pressure variability (SPV) and changes in POPW amplitude (ΔPOPW%), calculated using five consecutive snapshots from every patient’s monitor, were compared using linear regression, Pearson product–moment correlation, the Spearman rank method, and receiver operating characteristic (ROC) curve analysis. A strong correlation existed between respiratory SPV and ΔPOPW% for the detection of PP (r = 0.682; p < 0.0001). A respiratory variation in ΔPOPW% exceeding 25.44% (about one-fourth the amplitude of the tallest POP waveform) allowed detection of PP with a sensitivity of 86.7% and a specificity of 88%. Pulse oximetry is a readily available and easily performed noninvasive means for detecting PP in children.     

Determination of systolic blood pressure via pulse oximeter in transported pediatric patients.

OBJECTIVE: To compare pulse oximetry waveform systolic blood pressure measurements (POWSBP) to measurements obtained by noninvasive blood pressure measurement (NIBPM) during the transport of children. DESIGN: A prospective, convenience sample. SETTING AND PARTICIPANTS: All patients transported by a dedicated Pediatric Critical Care Transport Team were eligible for inclusion. Senior transport nurses with over 3 years of transport experience who had been instructed by the principal investigator (PI) in the technique, obtained the measurements and recorded the results. A convenience sample was obtained based on the presence or absence of one of the senior nurses on the transport team. METHODS: Measurements of blood pressure were obtained by POWSBP and NIBPM (PROPAQ@; Protocol Systems, Beaverton, OR) on pediatric patients during transport in moving ambulances or fixed wing aircraft. Measurement of systolic blood pressure by pulse oximetry (POWSBP) was obtained on all patients by observing the return of the plethysmographic waveform of the pulse oximeter as the blood pressure cuff deflated. The patients were divided into two groups; in group A POWSBP measurements were obtained by using the automated BP cuff from the PROPAQ@ and in group B by a manual BP cuff. These measurements were compared to NIBPM readings obtained at the same time. Between 3 and 13 paired readings were obtained for each patient. The actual transport time determined the number of measurements obtained. RESULTS: A total of 24 patients were enrolled in the study. Multiple matched pair readings (both POWSBP and NIBPM) were obtained from each patient for a total of 180 data points. A two variable linear regression model was run which identified a significant correlation between POWSBP and NIBPM. Group A, r = 0.7592 and r = 0.9477 for group B significant at P< 0.000001. Further, a corrective equation was developed for use with an automated BP cuff. CONCLUSIONS: The use of pulse oximetry waveform systolic blood pressure measurement is a quick and easy method with which to obtain systolic blood pressure in children during transport and shows a close correlation to the standard noninvasive blood pressure measurement. If an automated blood pressure cuff is used, then a corrective equation [NIBP-S = 41.686 + 0.7377(POBPS)] is required. Further validation in a larger group of patients is recommended.     

The value of pulsus paradoxus in assessing the child with status asthmaticus.

The presence of pulsus paradoxus (PP) in 13 episodes of status asthmaticus in 12 children, ages 13 months to 15 years, was compared sequentially to a clinical score, peak expiratory flow rate (PEFR), heart rate, arterialized capillary pH, carbon dioxide pressure (PCO2), and the ratio of inspired oxygen to oxygen pressure (FIO2)/PO2) during the first 48 hours following admission. There was a significant correlation (P less than .01) between the presence of a PP (greater than or equal to 5 mm Hg) and the clinical score (r = .79), PEFR (r = .55), and heart rate (r = .49). This was particularly striking when the PP was greater than or equal to 20 mm Hg. There was no significant correlation between the mean PP and the PCO2 or FIO2/PO2 ratio. However, a mean PCO2 exceeding 40 mm Hg was associated with a highly significant (P less than .005) difference in mean PP (22.2 mm Hg) compared to the mean PP (12.2 mm Hg) when the PCO2 was below 40 mm Hg. Although the PP technique can easily be learned by physician and nursing personnel, there are potential problems. The difficulties in children are compared to those in adults. The PP is a valuable clinical tool in assessing the severity of airway obstruction in status asthmaticus. The presence of a PP, particularly greater than 20 mm Hg, is associated with moderate to severe airway obstruction. In conjunction with the overall clinical status of the patient and frequent blood gas determinations, the PP allows for better evaluation of the patient with status asthmaticus.     

Noninvasive positive-pressure ventilation in children with lower airway obstruction.

STUDY OBJECTIVES: Mechanical ventilation of patients with severe lower airway obstruction presents significant risks; therefore, avoiding the intubation in these patients has been a principal goal of clinical management. Noninvasive positive-pressure ventilation has been shown to be effective in treating adults with chronic obstructive pulmonary disease, but its use has not been studied prospectively in children with acute obstructive lower airways disease. The objective of this study was to determine whether noninvasive mask ventilation improved respiratory function in children with asthma and other obstructive lower airways diseases. STUDY DESIGN: A prospective, randomized, crossover study. PATIENTS: A total of 20 children admitted to the pediatric intensive care unit with acute lower airway obstruction. METHODS: Children were randomized to receive either 2 hrs of noninvasive ventilation followed by crossover to 2 hrs of standard therapy or 2 hrs of standard therapy followed by 2 hrs of noninvasive ventilation. RESULTS: Using a Clinical Asthma Score, we found that noninvasive ventilation decreased signs of work of breathing such as respiratory rate, accessory muscle use, and dyspnea as compared with standard therapy. There was no serious morbidity associated with noninvasive ventilation. CONCLUSIONS: We conclude that noninvasive ventilation can be an effective treatment for children with acute lower airway obstruction.     

Pulse oximetry for continuous oxygen monitoring in sick newborn infants

We studied 54 neonates with acute cardiorespiratory illness and 21 infants with bronchopulmonary dysplasia, to evaluate the accuracy of a nonheated pulse oximeter in predicting arterial oxygen saturation (SaO2). We also studied the accuracy of transcutaneous oxygen tension (tcPO2) in estimating arterial oxygen tension (PaO2) in infants with bronchopulmonary dysplasia. We compared pulse oximeter SaO2 with simultaneously measured SaO2 (range 78% to 100%) using a co-oximeter. Over a wide range of values for heart rate, blood pressure, hematocrit, PO2, PCO2, and pH, linear regression analysis revealed a close correlation between in vivo pulse oximeter readings and in vitro SaO2 measurements in patients with acute (r = 0.86, Y = 29.64 + 0.68X) and chronic (r = 0.91, Y = 6.29 + 0.96X) disease. Regression analysis of tcPO2 versus PaO2 showed an r value of 0.76 in infants with bronchopulmonary dysplasia. In these patients the mean difference between pulse oximeter SaO2 and in vitro SaO2 was 2.9% +/- 1.8% (SD), whereas the mean difference between tcPO2 and PaO2 was -14.5 +/- 11.1 mm Hg. Fetal hemoglobin ranged from 4.3% to 95%. We conclude that pulse oximetry is an appropriate alternative to tcPO2 for continuous oxygen monitoring in newborn infants with acute cardiorespiratory illnesses and chronic lung disease.     

Use of pulse oximetry for blood pressure measurement after cardiac surgery

Blood pressure measurement using pulse oximeter waveform change was compared with an oscillometric measurement and the gold standard, intra-arterial measurement, in children after cardiac surgery. Forty six patients were enrolled and divided into groups according to weight. Simultaneous blood pressure measurements were obtained from the arterial catheter, the oscillometric device, and the pulse oximeter. Pulse oximeter measurements were obtained with a blood pressure cuff proximal to the oximeter probe. The blood pressure measurements from the pulse oximeter method correlated better with intra-arterial measurements than those from the oscillometric device (0.77-0.96 v 0.42-0.83). The absolute differences between the pulse oximeter and intra-arterial measurements were significantly smaller than between the oscillometric and intra-arterial measurements in children less than 15.0 kg. The pulse oximeter waveform change is an accurate and reliable way to measure blood pressure in children non-invasively, and is superior to the oscillometric method for small patients.     

Pulse oximetry in pediatric intensive care: comparison with measured saturations and transcutaneous oxygen tension

We evaluated a new pulse oximeter designed to monitor beat-to-beat arterial oxygen saturation (SaO2) and compared the monitored SaO2 with arterial samples measured by co-oximetry. In 40 critically ill children (112 data sets) with a mean age of 3.9 years (range 1 day to 19 years), SaO2 ranged from 57% to 100%, and PaO2 from 27 to 128 mm Hg, heart rates from 85 to 210 beats per minute, hematocrit from 20% to 67%, and fetal hemoglobin levels from 1.3% to 60%; peripheral temperatures varied between 26.5 degrees and 36.5 degrees C. Linear correlation analysis revealed a good agreement between simultaneous pulse oximeter values and both directly measured SaO2 (r = 0.95) and that calculated from measured arterial PaO2 (r = 0.95). The device detected several otherwise unrecognized drops in SaO2 but failed to function in four patients with poor peripheral perfusion secondary to low cardiac output. Simultaneous measurements with a tcPO2 electrode showed a similarly good correlation with PaO22 (r = 0.91), but the differences between the two measurements were much wider (mean 7.1 +/- 10.3 mm Hg, range -14 to +49 mm Hg) than the differences between pulse oximeter SaO2 and measured SaO2 (1.5% +/- 3.5%, range -7.5% to -9%) and were not predictable. We conclude that pulse oximetry is a reliable and accurate noninvasive device for measuring saturation, which because of its rapid response time may be an important advance in monitoring changes in oxygenation and guiding oxygen therapy.     

Pulse oximetry: an alternative method for the assessment of oxygenation in newborn infants

Continuous monitoring of oxygenation in sick newborns is vitally important. However, transcutaneous PO2 measurements have a number of limitations. Therefore, we report the use of the pulse oximeter for arterial oxygen saturation (SaO2) determination in 26 infants (birth weights 725 to 4,000 g, gestational ages 24 to 40 weeks, and postnatal ages one to 49 days). Fetal hemoglobin determinations were made on all infants and were repeated following transfusion. SaO2 readings from the pulse oximeter were compared with the SaO2 measured in vitro on simultaneously obtained arterial blood samples. The linear regression equation for 177 paired measurements was: y = 0.7x + 27.2; r = .9. However, the differences between measured SaO2 and the pulse oximeter SaO2 were significantly greater in samples with greater than 50% fetal hemoglobin when compared with samples with less than 25% fetal hemoglobin (P less than .001). The pulse oximeter was easy to use, recorded trends in oxygenation instantaneously, and was not associated with skin injury. We conclude that pulse oximetry is a reliable technique for the continuous, noninvasive monitoring of oxygenation in newborn infants.     

Noninvasive determination of oxygen saturation using pulse oximetry in pediatric cardiology

Pulse oximetry is a relatively new noninvasive method to measure arterial oxygen saturation (SO2). We evaluated the reliability of a pulse oximeter (N-100, Nellcor/Drger, Lübeck) in single and continuous measurements of SO2. During cardiac catheterisation we compared pulse oximeter (puls.SO2) measurements to those in simultaneously taken arterial samples (art.SO2), and obtained 203 pair measurements in 85 patients, mostly newborns and infants; in 20 of them before and during the breathing of oxygen through a mask. We also have 67 pair measurements of capillary blood samples (kap.SO2) and puls.SO2. Continuous measurements with the pulse oximeter were carried out in 17 patients for up to 116 h. Our main results are: 1. In the puls.SO2 range of 66% to 100% the measurements with the pulse oximeter were accurate (r = 0.97, Syx = 2.1). Below 66% the puls.SO2 values were on average much higher than the art.SO2 values, with an increased variance. Intraindividual oxygenation changes before and during the breathing of oxygen were accurately measured. 2. Pulse oximetry is much more informative than kap.SO2 measurements, because its information about the SO2 before blood sampling (= resting value) and following SO2 changes during the painful procedure (= stress values). 3. Continuous measurements with the pulse oximeter are very simple and very reliable and are not associated with skin injury. Because the pulse oximeters responses rapid to oxygenation changes and does not need calibration it is very valuable in the assessment of therapeutic procedures in patients with cyanotic heart disease. We conclude that the pulse oximeter is a very important new diagnostic tool in pediatric cardiology.     

Use of pulse oximetry for blood pressure measurement after cardiac surgery

Blood pressure measurement using pulse oximeter waveform change was compared with an oscillometric measurement and the gold standard, intra-arterial measurement, in children after cardiac surgery. Forty six patients were enrolled and divided into groups according to weight. Simultaneous blood pressure measurements were obtained from the arterial catheter, the oscillometric device, and the pulse oximeter. Pulse oximeter measurements were obtained with a blood pressure cuff proximal to the oximeter probe. The blood pressure measurements from the pulse oximeter method correlated better with intra-arterial measurements than those from the oscillometric device (0.77-0.96 v 0.42-0.83). The absolute differences between the pulse oximeter and intra-arterial measurements were significantly smaller than between the oscillometric and intra-arterial measurements in children less than 15.0 kg. The pulse oximeter waveform change is an accurate and reliable way to measure blood pressure in children non-invasively, and is superior to the oscillometric method for small patients.

     

Pulse oximetry is a poor predictor of hypoxemia in stable children with sickle cell disease

OBJECTIVE: To evaluate the accuracy of the pulse oximeter to detect hypoxemia in patients with sickle cell disease in an ambulatory care setting. STUDY DESIGN: Simultaneous measurements of PaO(2), arterial oxygen saturation by co-oximetry (criterion standard), and pulse oximetry were performed in 21 children with sickle cell disease during 22 outpatient visits. The bias and precision of the pulse oximeter compared with measured arterial oxygen saturation by co-oximetry were determined. The sensitivity, specificity, and positive and negative predictive values of the pulse oximeter to detect hypoxemia (PaO(2) <70 mm Hg) were also calculated. RESULTS: The mean difference between pulse oximetry and measured oxygen saturation (bias) was 5.0% and the SD (precision) was 5.3. Twenty-one patients had a PaO(2) greater than 70 mm Hg; 7 of these (33%) were predicted to be hypoxic by pulse oximetry with values less than 93%, for a specificity to detect normoxia of 67%. CONCLUSION: Making treatment decisions based on pulse oximetry data alone in patients with sickle cell disease who are not acutely ill may be inappropriate.     

Hyperoxemia in newborn infants: detection by pulse oximetry

Pulse oximetry has been proposed as a noninvasive continuous method for transcutaneous monitoring of arterial oxygen saturation of hemoglobin (tcSO2) in the newborn infant. The reliability of this technique in detecting hyperoxemia is controversial, because small changes in saturation greater than 90% are associated with relatively large changes in arterial oxygen tension (PaO2). The purpose of this study was to assess the reliability of pulse oximetry using an alarm limit of 95% tcSO2 in detecting hyperoxemia (defined as PaO2 greater than 90 mm Hg) and to examine the effect of varying the alarm limit on reliability. Two types of pulse oximeter were studied alternately in 50 newborn infants who were mechanically ventilated with indwelling arterial lines. Three arterial blood samples were drawn from every infant during routine increase of inspired oxygen before intratracheal suction, and PaO2 was compared with tcSO2. The Nellcor N-100 pulse oximeter identified all 26 hyperoxemic instances correctly (sensitivity 100%) and alarmed falsely in 25 of 49 nonhyperoxemic instances (specificity 49%). The Ohmeda Biox 3700 pulse oximeter detected 13 of 35 hyperoxemic instances (sensitivity 37%) and alarmed falsely in 7 of 40 nonhyperoxemic instances (specificity 83%). The optimal alarm limit, defined as a sensitivity of 95% or more associated with maximal specificity, was determined for Nellcor N-100 at 96% tcSO2 (specificity 38%) and for Ohmeda Biox 3700 at 89% tcSO2 (specificity 52%). It was concluded that pulse oximeters can be highly sensitive in detecting hyperoxemia provided that type-specific alarm limits are set and a low specificity is accepted.     

Pulse oximetry in ventilated preterm newborns: reliability of detection of hyperoxaemia and hypoxaemia, and feasibility of alarm settings

The aim of our study was to evaluate the reliability of pulse oximetry in detecting both hyper- and hypoxaemic states and to create clinically feasible alarm limits. A total of 792 readings of a pulse oximeter and corresponding values of arterial oxygen tension from 146 (79M, 67F) artificially ventilated preterm newborns with indwelling umbilical artery catheters were compared. Predictive value analysis of pulse oximeter readings related to arterial oxygen tension confirmed the ability of the pulse oximeter to identify both hypoxaemia and hyperoxaemia. However, a clinically feasible and safe range of alarm limits for maintenance of arterial oxygen tension of 40-90 mmHg (5.3-12kPa) could only be established at a sensitivity level less than 0.9. At a level of 0.85, the alarm range on the pulse oximeter was 92.5-95%. Based on these findings, we are concerned about using pulse oximetry as the sole means of oxygen monitoring for preterm infants receiving supplementary oxygen. A combination of the pulse oximetry with other methods of blood-gas monitoring seems mandatory     

The clinical utility of pulse oximetry in the pediatric emergency department setting.

Pulse oximetry provides a noninvasive, painless, accurate, and rapid method for measuring arterial oxygen saturation (SaO2). It has been shown to be valuable in anesthesia and critical care and recently has been used extensively in the outpatient setting. As is often the case with new technologies, little has been published on the basic issues of reliability, reproducibility, and effect on patient care. This prospective clinical study evaluated the basic principles of pulse oximetry in the pediatric emergency department setting and tested the hypotheses that pulse oximetry SaO2 measurements are reliable and provide valuable information, in addition to clinical and laboratory data which affect patient assessment and management. One hundred twenty patients were enrolled in phase 1 and 437 in phase 2 of the study. Pulse oximetry readings were reproducible with an intraclass correlation of 0.87. SaO2 measurements changed the assessed degree of illness in 188 (53%) patients; 47 (13%) were felt to be more ill and 130 (37%) to be less ill than at initial assessment. Sixty-nine (17%) patients were identified in whom SaO2 readings changed management plans; 27 (8%) were managed more aggressively (intubation, surgery, or admission), while 40 (11%) were managed less aggressively (discharged). In three cases, pulse oximetry was instrumental in the diagnosis of a serious illness. The results from this study indicate that pulse oximetry SaO2 readings are stable and reproducible and provide information which impacts significantly on patient assessment and management.     

Hemoglobin desaturation during sleep and daytime in patients with cystic fibrosis and severe airway obstruction

Transcutaneous hemoglobin saturation by pulse oximetry was evaluated during sleep and for 2-3 h during the day in 31 patients with cystic fibrosis (median age 15.2 years; range 7.6-33.6 years) and severe airway obstruction. Pulse oximetry readings were analyzed as a cumulative percentage of time in which oxygen saturation was < 90% during both sleep and daytime. Each patient was also examined using clinical and radiological scores, spirometry and arterial blood-gas analysis. The agreement between arterial and transcutaneous saturation was evaluated in 29 patients. The difference between transcutaneous and arterial saturation was 2.4 +/- 2.0% and it increased as arterial saturation decreased. Clinical and radiological scores and spirometry parameters showed a poor correlation with both overnight and daytime desaturation. An arterial saturation < 94% may indicate a risk of consistent desaturation. This occurred for more than 50% of the time in 11 of 20 patients during sleep and in 5 of 20 patients during daytime hours.     

An automated algorithm for determining respiratory rate by photoplethysmogram in children

Background: We have developed an automated algorithm to allow the measurement of respiratory rate directly from the photoplethysmogram (pulse oximeter waveform). Aim: To test the algorithm's ability to determine respiratory rate in children. Methods: A convenience sample of patients attending a paediatric Accident and Emergency Department was monitored using a purpose-built pulse oximeter and the photoplethysmogram (PPG) recorded. Respiration was also recorded by an observer activating a push-button switch in synchronization with the child's breathing. The switch marker signals were processed to derive a manual respiratory rate that was compared with the wavelet-based oximeter respiratory rate derived from the PPG signal. Results: Photoplethysmograms were obtained from 18 children aged 18 mo to 12 y, breathing spontaneously at rates of 17 to 27 breaths per minute. There was close correspondence between the wavelet-based oximeter respiration rate and the manual respiratory rate, with the difference between them being less than one breath per minute in all children.

Conclusion: Our automated algorithm allows the accurate determination of respiratory rate from photoplethysmograms of a heterogeneous group of children. We believe that our automated wavelet-based signal-processing techniques could soon be easily incorporated into current pulse oximetry technology.     

电子支气管镜在儿童上气道梗阻性疾病中的诊断价值

目的 评价电子支气管镜在儿童上气道梗阻性疾病中的诊断价值及安全性.方法 对91例上气道梗阻患儿行电子支气管镜检查,总结分析病因.结果 (1) 儿童上气道梗阻病因依次为先天性喉气管软化合并感染(45例)、声门下异物(13例)、喉气管占位性病变(9例)、声门区水肿(6例)、气管狭窄(5例)、喉咽腔病变(咽后脓肿3例、肿物2例)、声门区增生(3例)、声门下狭窄(2例)、声带麻痹(2例)、喉蹼(1例);(2) 不同年龄段病因不同:新生儿期依次为声带麻痹、喉气管软化;~6个月依次为先天性喉气管软化、会厌囊肿,其他少见病因如气管狭窄、咽后脓肿、喉蹼等疾病;~1岁依次为喉气管软化、气管狭窄、声门下异物等;~3岁依次为声门下异物、声门区水肿、喉气管软化等;>3岁儿童1例为喉乳头状瘤.(3) 疾病好发的年龄段不同:先天性喉气管软化好发于6个月以下婴儿,气管异物好发于1~3岁幼儿,先天性会厌囊肿多见于3个月以下婴儿.(4) 并发症:16例有一过性血氧饱和度下降,11例出现气管支气管痉挛,术后8例有一过性发热,6例有短期喉鸣加重.结论 电子支气管镜在儿童上气道梗阻性疾病的诊断中起重要作用,可迅速、直观地判断病变部位和性质,避免误诊,有助于指导治疗.

Abstract：

Objective To investigate the diagnostic value and safety of bronchovideoscope in the pediatric upper airway obstruction.Methods Bronchovideoscope was performed in 91 pediatric patients with upper airway obstruction.The etiology was analyzed and summarized.Results (1) Our study showed that the etiology of pediatric upper airway obstruction were as follow in turn:congenital laryngo-trachemalacia (45 cases),subglottic foreign body (13 cases),laryngotracheal occupying lesion (9 cases),vocal area edema (6 cases),tracheal stenosis (5 cases),laryngopharyngeal lesion (3 cases of retropharyngeal abscess,2 cases of tumor),vocal area hyperplasia (3 cases),subglottic stenosis (2 cases),glottic paralysis (2 cases),laryngeal web (1 case).(2) The common etiology of pediatric upper airway obstruction was different with age.Neonatal period:glottic paralysis,laryngomalacia in turn;1~6 month:laryngo-trachemalacia,tracheal stenosis,subglottic foreign body in turn;1~3 year:subglottic foreign body,vocal area edema,laryngo-trachemalacia in turn,>3 year:laryngeal papilloma.(3) Specific disease had predominant age:laryngo-trachemalacia predominated in infants less than 6 month;tracheal foreign body was most common in child aged 1~3 years old;epiglottic cyst was most common in infant less than 3 month.(4) Complication:during procedure,16 patients had transient decrease of saturation of blood oxygen and 11 patients had tracheobronchial spasm.After procedure,8 patients had transient fever and 6 patients had transient aggravation of laryngeal stridor.Conclusion Bronchovideoscope plays an important role in the diagnosis of pediatric upper airway obstruction.It can directly identify position and nature of disease,and then guide treatment.     

Pulse oximetry in very low birth weight infants with acute and chronic lung disease

With improved survival of very low birth weight infants, the incidence of bronchopulmonary dysplasia has significantly increased. Pulse oximetry appears to be an adequate alternative to transcutaneous PO2, for continuous arterial oxygen saturation (SaO2) monitoring in neonates; however, its usefulness has not been very well documented in very low birth weight infants. We studied 68 patients with birth weight less than 1,250 g; 44 neonates had respiratory distress syndrome and 24 had bronchopulmonary dysplasia. Using a Nellcor N-100 pulse oximeter, we compared transcutaneous oxygen saturation with simultaneous arterial samples analyzed for SaO2 (range 78% to 100%) using an IL 282 co-oximeter. Fetal hemoglobin was measured in 66 patients. We also evaluated the accuracy of transcutaneous PO2 in reflecting arterial PO2 in patients with bronchopulmonary dysplasia. Over a wide range of PO2, PCO2, pH, heart rate, BP, hematocrit, and fetal hemoglobin, linear regression analysis revealed a close correlation between pulse oximeter values and co-oximeter measured SaO2 in patients with acute (r = .88, Y = 19.41 + 0.79X) and chronic (r = .90, Y = 9.72 + 0.92X) disease. Regression analysis of transcutaneous v arterial PO2 in infants with bronchopulmonary dysplasia showed an r value of .78. In addition, in these patients with chronic disease, the mean difference between pulse oximeter SaO2 and co-oximeter measured SaO2 was 2.7 +/- 1.9% (SD); whereas the mean difference between transcutaneous and arterial PO2 was -14 +/- 10.7 mm Hg. Our findings indicate that pulse oximetry can be used reliably in very low birth weight infants with acute and chronic lung disease, for SaO2 values greater than 78%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical use of continuous arterial blood gas monitoring in the pediatric intensive care unit

CONTEXT: Continuous arterial blood gas monitoring is a new technology based on the combination of opto-chemical and fiber-optic detectors that can measure pH, PCO2, PO2, and temperature on a continuous basis via a sensor placed in an artery. OBJECTIVE: To evaluate this technology in pediatric patients who would normally require frequent arterial blood gas sampling. DESIGN: A criterion standard study in which the results of arterial blood gas samples measured by the laboratory analyzer were compared with the sensor readings. SETTING: A pediatric intensive care unit of a tertiary referral center. PATIENTS: Children with severe respiratory failure who required frequent arterial blood gas sampling and who had a 20-gauge arterial line in either a radial or femoral site. RESULTS: Twenty-four patients with a mean age of 6.4 years (range 1-21 years) had a sensor placed. Sensors were in place for a mean of 101 +/- 62 hours. Eighteen patients underwent continuous monitoring for at least 24 hours or until no longer clinically necessary. There were 414 pairs of blood gas samples obtained. The bias/precision for pH was 0.005/0.030; for PCO2, -1.8/6.3 mm Hg; and for PO2, 1.2/24 mm Hg. The correlation (r value) between the sensor readings and the blood gases were pH 0. 960, PCO2 0.927, PO2 0.813 (P <.01 for all values). The bias and precision for PO2 levels < 70 mm Hg were 0.057/9.34 mm Hg. There were no complications from sensor placement. Continuous blood gas monitoring allowed immediate recognition of clinical changes. CONCLUSION: The continuous arterial blood gas sensor is capable of clinically accurate blood gas measurements. This technology provides the clinician with immediate data that can allow rapid interventions in unstable patients.     

High-flow nasal cannula in children with asthma exacerbation: A review of current evidence

Asthma is the commonest obstructive airway disease and the leading cause of morbidity in children. In the pediatric population, acute exacerbations of asthma are a frequent cause of presentations and hospital admissions. An acute asthma exacerbation is potentially life-threatening; it is predominantly treated using conventional oxygen therapy with bronchodilators and systemic corticosteroids. The treatment of those who do not respond to conventional therapy is escalated to noninvasive positive pressure ventilation (NIPPV) before invasive ventilation. Although NIPPV has demonstrated benefits and safety, it still has limitations such as treatment intolerance caused mainly by discomfort and complications. High-flow oxygen therapy administered through a nasal cannula (HFNC) provides respiratory support with adequate airway humidity and has demonstrated safety and benefits in clinical practice. In the present review, we discuss HFNC and variations in HFNC use, focusing on its feasibility and current evidence of using it on children with asthma exacerbations.