Pulse oximetry for monitoring infants in the delivery room: a review.
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Delivery, Obstetric↗
Biomedical subjects
C J Morley
Publications and source records attributed to C J Morley.
Predicting successful extubation of very low birthweight infants.
OBJECTIVE: To determine the accuracy of three tests used to predict successful extubation of preterm infants. STUDY DESIGN: Mechanically ventilated infants with birth weight <1250 g and considered ready for extubation were changed to endotracheal continuous positive airway pressure (ET CPAP) for three minutes. Tidal volumes, minute ventilation (V e), heart rate, and oxygen saturation were recorded before and during ET CPAP. Three tests of extubation success were evaluated: (a) expired V e during ET CPAP; (b) ratio of V e during ET CPAP to V e during mechanical ventilation (V e ratio); (c) the spontaneous breathing test (SBT)-the infant passed this test if there was no hypoxia or bradycardia during ET CPAP. The clinical team were blinded to the results, and all infants were extubated. Extubation failure was defined as reintubation within 72 hours of extubation. RESULTS: Fifty infants were studied and extubated. Eleven (22%) were reintubated. The SBT was the most accurate of the three tests, with a sensitivity of 97% and specificity of 73% and a positive and negative predictive value for extubation success of 93% and 89% respectively. CONCLUSION: The SBT used just before extubation of infants <1250 g may reduce the number of extubation failures. Further studies are required to establish whether the SBT can be used as the primary determinant of an infant's readiness for extubation.
Continuous Positive Airway Pressure↗
Volume-targeted versus pressure-limited ventilation in the neonate.
BACKGROUND: Inflammation caused by lung overdistension (volutrauma) is thought to be important in the pathogenesis of bronchopulmonary dysplasia (BPD). Preterm infants with variable lung compliance are particularly at risk. Volume-targeted neonatal ventilators have been developed as alternatives to traditional pressure-limited ventilators. They deliver consistent, appropriate tidal volumes with the aim of reducing lung damage. It is suggested that these would provide an effective, safer means of ventilating the newborn infant. OBJECTIVES: To determine whether volume-targeted ventilation compared with pressure-limited ventilation leads to reduced rates of death and BPD in newborn infants. Secondary objectives were to determine whether use of volume modes affected clinical outcomes such as incidence of airleak, growth, duration of ventilation or cranial ultrasound findings. SEARCH STRATEGY: The search strategy comprised searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2004), MEDLINE PubMed 1966 to November 2004, and hand searches of reference lists of relevant articles and conference proceedings. SELECTION CRITERIA: All randomised and quasi-randomised trials comparing the use of volume-targeted versus pressure-limited ventilation in neonates in the first 28 days of life. DATA COLLECTION AND ANALYSIS: Two authors assessed the methodological quality of eligible trials and extracted data independently. When appropriate, meta-analysis was conducted to provide a pooled estimate of effect. For categorical data the relative risk (RR) and risk difference (RD) were calculated with 95% confidence intervals. Number needed to treat was calculated when RD was statistically significant. Continuous data were analysed using weighted mean difference (WMD). MAIN RESULTS: Four randomised trials were identified that addressed the outcomes of this review, recruiting a total of 178 preterm infants. All were recruited during the first 72 hours of life. Caregivers and those evaluating the outcomes of trials were not masked. All trials report high rates of follow-up, although one trial with uneven patient distribution may have had some post-randomisation attrition. No significant difference was found for death by hospital discharge, and no trials reported the combined outcome of death or BPD. When secondary outcomes were examined, pooled analysis of the trials showed that volume-targeted ventilation resulted in significant reductions in duration of ventilation [WMD -2.93 days (-4.28, -1.57)] and rates of pneumothorax [typical RR 0.23 (0.07, 0.76), RD -0.11 (-0.20, -0.03), NNT 9]. There was also a significant difference in rates of severe (Grade 3 or 4) intraventricular haemorrhage favouring the volume-targeted group [typical RR 0.32 (0.11, 0.90), RD -0.16 (-0.29, -0.03), NNT 6]. There was a reduction in the incidence of BPD (supplemental oxygen at 36 weeks) amongst surviving infants, of borderline statistical significance [typical RR 0.34 (0.11, 1.05), RD -0.14 (-0.27, 0.00), NNT=7]. No significant differences were found for failure of mode of ventilation, use of neuromuscular paralysis, patent ductus arteriosus, airleak of any sort or pulmonary interstitial emphysema alone, cranial ultrasound abnormalities or periventricular leucomalacia. None of the trials addressed growth, death after discharge from hospital or neurodevelopmental outcome. AUTHORS' CONCLUSIONS: Although rates of death and BPD were not significantly different between the two ventilator strategies, statistically significant effects favouring volume targeting were shown for some clinically important outcomes. However, the numbers of trials and infants randomised are small and further studies are required to confirm the role of volume targeting in neonatal ventilation.
Bronchopulmonary Dysplasia↗
Volume guarantee ventilation, interrupted expiration, and expiratory braking.
BACKGROUND: In volume guarantee ventilation with the Dräger Babylog 8000 ventilator, inspiratory and expiratory flows are monitored and the expiratory tidal volume calculated following each inflation. The pressure for the next inflation is modified to ensure the expired tidal volume is close to the set value. AIM: To investigate interrupted expiration observed during volume guarantee ventilation of spontaneously breathing, ventilated infants. METHODS: Spontaneously breathing infants, ventilated with volume guarantee, had recordings of gas flow, ventilator pressures, tidal volume waveforms, oximetry, heart rate, and transcutaneous oxygen and carbon dioxide during 10 minute recordings. RESULTS: A total of 6540 inflations were analysed from 10 infants; 62% were triggered. Two different patterns were found: (1) Normal volume guarantee pattern with 97% of triggered and 91% untriggered inflations. It had a normal expiratory curve and a mean expired tidal volume within 3% of the set volume, but a large variation due to the babies' breathing. (2) A pattern of interrupted expiratory flow after approximately 3% of inflations due to a small inspiration (approximately 1.3 ml/kg) during expiration. This led the ventilator to calculate an inappropriate total expired tidal volume for that inflation and an increase in the pressure for the next inflation. CONCLUSIONS: After about 3% of inflations, with volume guarantee ventilation, interruption of the expiration causes an increased pressure for the next inflation of approximately 4.9 cm H2O, compared with normal volume guarantee inflation. The interrupted expiration is most likely to be due to diaphragmatic braking.
Diaphragm↗
Neonatal resuscitation 1: a model to measure inspired and expired tidal volumes and assess leakage at the face mask.
BACKGROUND: Neonatal resuscitation is a common and important intervention, and adequate ventilation is the key to success. In the delivery room, positive pressure ventilation is given with manual ventilation devices using face masks. Mannequins are widely used to teach and practise this technique. During both simulated and real neonatal resuscitation, chest excursion is used to assess tidal volume delivery, and leakage from the mask is not measured. OBJECTIVE: To describe a system that allows measurement of mask leakage and estimation of tidal volume delivery. METHODS: Respiratory function monitors, a modified resuscitation mannequin, and a computer were used to measure leakage from the mask and to assess tidal volume delivery in a model of neonatal resuscitation. RESULTS: The volume of gas passing through a flow sensor was measured at the face mask. This was a good estimate of the tidal volume entering and leaving the lung in this model. Gas leakage between the mask and mannequin was also measured. This occurred principally during inflation, although gas leakage during deflation was seen when the total leakage was large. A volume of gas that distended the mask but did not enter the lung was also measured. CONCLUSION: This system can be used to assess the effectiveness of positive pressure ventilation given using a face mask during simulated neonatal resuscitation. It could be useful for teaching neonatal resuscitation and assessing ventilation through a face mask.
Education, Medical, Graduate↗
Neonatal resuscitation 2: an evaluation of manual ventilation devices and face masks.
BACKGROUND: The key to successful neonatal resuscitation is effective ventilation. Little evidence exists to guide clinicians in their choice of manual ventilation device or face mask. The expiratory tidal volume measured at the mask (V(TE(mask))) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. AIM: To compare the efficacy of (a) the Laerdal infant resuscitator and the Neopuff infant resuscitator, used with (b) round and anatomically shaped masks in a model of neonatal resuscitation. METHODS: Thirty four participants gave positive pressure ventilation to a mannequin at specified pressures with each of the four device-mask combinations. Flow, inspiratory tidal volume at the face mask (V(TI(mask))), V(TE(mask)), and airway pressure were recorded. Leakage from the mask was calculated from V(TI(mask)) and V(TE(mask)). RESULTS: A total of 10,780 inflations were recorded and analysed. Peak inspiratory pressure targets were achieved equally with the Laerdal and Neopuff resuscitators. Positive end expiratory pressure was delivered with the Neopuff but not the Laerdal device. Despite similar peak pressures, V(TE(mask)) varied widely. Mask leakage was large for each combination of device and mask. There were no differences between the masks. CONCLUSION: During face mask ventilation of a neonatal resuscitation mannequin, there are large leaks around the face mask. Airway pressure is a poor proxy for volume delivered during positive pressure ventilation through a mask.
Air Pressure↗
Neonatal resuscitation 3: manometer use in a model of face mask ventilation.
BACKGROUND: Adequate ventilation is the key to successful neonatal resuscitation. Positive pressure ventilation (PPV) is initiated with manual ventilation devices via face masks. These devices may be used with a manometer to measure airway pressures delivered. The expiratory tidal volume measured at the mask (V(TE(mask))) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. AIM: To assess the effect of viewing a manometer on the peak inspiratory pressures used, the volume delivered, and leakage from the face mask during PPV with two manual ventilation devices in a model of neonatal resuscitation. METHODS: Participants gave PPV to a modified resuscitation mannequin using a Laerdal infant resuscitator and a Neopuff infant resuscitator at specified pressures ensuring adequate chest wall excursion. Each participant gave PPV to the mannequin with each device twice, viewing the manometer on one occasion and unable to see the manometer on the other. Data from participants were averaged for each device used with the manometer and without the manometer separately. RESULTS: A total of 7767 inflations delivered by the 18 participants were recorded and analysed. Peak inspiratory pressures delivered were lower with the Laerdal device. There were no differences in leakage from the face mask or volumes delivered. Whether or not the manometer was visible made no difference to any measured variable. CONCLUSIONS: Viewing a manometer during PPV in this model of neonatal resuscitation does not affect the airway pressure or tidal volumes delivered or the degree of leakage from the face mask.
Air Pressure↗
Monitoring of end tidal carbon dioxide and transcutaneous carbon dioxide during neonatal transport.
OBJECTIVE: To assess the accuracy of measurements of end tidal carbon dioxide (CO2) during neonatal transport compared with arterial and transcutaneous measurements. DESIGN: Paired end tidal and transcutaneous CO2 recordings were taken frequently during road transport of 21 ventilated neonates. The first paired CO2 values were compared with an arterial blood gas. The differences between arterial CO2 (Paco2), transcutaneous CO2 (TcPco2), and end tidal CO2 (Petco2) were analysed. The Bland-Altman method was used to assess bias and repeatability. RESULTS: Petco2 correlated strongly with Paco2 and TcPco2. However, Petco2 underestimated Paco2 at a clinically unacceptable level (mean (SD) 1.1 (0.70) kPa) and did not trend reliably over time within individual subjects. The Petco2 bias was independent of Paco2 and severity of lung disease. CONCLUSIONS: Petco2 had an unacceptable under-recording bias. TcPco2 should currently be considered the preferred method of non-invasive CO2 monitoring for neonatal transport.
Blood Gas Monitoring, Transcutaneous↗
Pharyngeal pressure in preterm infants receiving nasal continuous positive airway pressure.
Pharyngeal pressures in 11 preterm infants, receiving binasal Hudson prong continuous positive airway pressure (CPAP) pressurised by bubbling bottles, were measured. The mean (95% confidence interval) pressure drop from the prongs to the pharynx was 3.2 (2.6 to 3.7) cm H(2)O with mouths open and 2.2 (1.6 to 2.8) cm H(2)O with mouths closed. Mouth closure augments CPAP transmission.
Air Pressure↗
Respiratory function monitoring during neonatal emergency transport.
This study reports for the first time the use of a respiratory function monitor in a prospective observational cohort of ventilated babies during transport. All 17 babies achieved target transcutaneous carbon dioxide tension within 15 minutes. Fifteen babies had improved ventilation with changes guided by the respiratory function monitor. The monitor was easy to use and useful.
Emergencies↗
Obtaining pulse oximetry data in neonates: a randomised crossover study of sensor application techniques.
Pulse oximetry may be useful during neonatal resuscitation. A randomised crossover study was performed to determine the most efficient method of applying the sensor. Applying it to the infant before connecting to the oximeter resulted in quickest acquisition of accurate heart rate. This technique should be preferred during resuscitation.
Cross-Over Studies↗
What do parents think about enrolling their premature babies in several research studies?
OBJECTIVE: To investigate parents' opinions about enrolling their premature baby into several research studies in the few days after birth. METHODOLOGY: A questionnaire was given to parents of premature babies in the neonatal intensive care unit who had been invited to join several studies (two to seven). RESULTS: All 50 mothers and 42 of 48 fathers completed the questionnaire independently; 28% had been asked to join two studies, 32% three, 24% four, 14% five, and 2% six studies. There were 61 babies with mean (SD) gestational age 26.9 (1.6) weeks and birth weight 877 (249) g. Nearly three quarters (71%) of the parents thought it was very good for their baby to be in a hospital that was carrying out a lot of research. Most (93%) thought that their baby would get the same or better care in a study. Only 15% thought their baby was too small for research studies. Almost all (98%) wanted to be involved in the decision about their baby joining a study. Only 22% were worried about the number of studies; 10% would not enroll their baby in any studies, but 74% were willing for their baby to join two or more studies, and 10% would enroll in all the studies. Most (94%) believed that their baby's participation would improve care of future babies. CONCLUSIONS: Most of these parents were willing to join several studies. The majority were not worried about their baby participating in the studies. The profession needs to be aware that parents are supportive of neonatal research and participation in multiple studies.
Adult↗
Nasal continuous positive airway pressure: does bubbling improve gas exchange?
In a randomised crossover trial, 26 babies, treated with Hudson prong continuous positive airway pressure (CPAP) from a bubbling bottle, received vigorous, high amplitude, or slow bubbling for 30 minutes. Pulse oximetry, transcutaneous carbon dioxide, and respiratory rate were recorded. The bubbling rates had no effect on carbon dioxide, oxygenation, or respiratory rate.
Carbon Dioxide↗
Cytomegalovirus remains viable in naturally infected breast milk despite being frozen for 10 days.
Cytomegalovirus culture positive breast milk was obtained from four mothers of very premature babies. The milk was stored at 0-5 degrees C in a domestic refrigerator for 48 hours or frozen for different durations at -20 degrees C. Cytomegalovirus survived in breast milk despite being frozen for 10 days at -20 degrees C.
Adult↗
Neonatal resuscitation: review of ventilation equipment and survey of practice in Australia and New Zealand.
OBJECTIVE: The equipment used to provide positive pressure ventilation at neonatal resuscitation varies between institutions. Available devices were reviewed and their use surveyed in a geographically defined region. The aim of this study was to establish which resuscitation equipment is used at neonatal intensive care units in Australia and New Zealand. METHODS: A questionnaire was sent to a neonatologist at each of the 29 neonatal intensive care units in Australia and New Zealand, asking which resuscitation equipment they used. If it was not returned, follow up was by email and telephone. RESULTS: Data was obtained from all units. Round face masks are used at all centres. Anatomically shaped masks are infrequently used at two of the three centres (10%) that have them. Straight endotracheal tubes are used exclusively at 23 (79%) centres. Shouldered tubes are used infrequently at three of the six centres that have them. The Laerdal Infant Resuscitator self-inflating bag is used at 22 (76%) centres. Flow-inflating bags are used at 12 (41%) centres. The Neopuff Infant Resuscitator is used at 14 (48%) centres. Varying oxygen concentrations are provided at delivery at 6/25 (24%) centres. CONCLUSIONS: There is a paucity of evidence for the efficacy of the equipment used currently to resuscitate newborn infants. This complete survey of the tertiary centres in a geographical region shows considerable variation in practice, reflecting this lack of evidence and consequent uncertainty among clinicians. Further research is necessary to determine which devices are preferable for this most important and common intervention.
Australia↗
Positive pressure ventilation at neonatal resuscitation: review of equipment and international survey of practice.
BACKGROUND: The equipment used to provide positive pressure ventilation to newborns needing resuscitation at delivery varies between institutions. Devices were reviewed and their use surveyed in a sample of neonatal centres worldwide. AIM: To determine which equipment is used to resuscitate newborns at delivery in a sample of teaching hospitals around the world. METHODS: A questionnaire was sent via e-mail to a neonatologist at each of 46 NICUs in 23 countries on five continents, asking which resuscitation equipment they used. If it was not returned, follow-up was by e-mail. RESULTS: Data were obtained from 40 (87%) centres representing 19 countries. Round face masks are used at 34 (85%) centres, anatomically shaped masks are used exclusively at six (15%) and a mixture of types are used at 11 (28%). Straight endotracheal tubes are used exclusively at 36 (90%) centres: shouldered tubes are used infrequently at three of the four centres that have them. The self-inflating bag is the most commonly used manual ventilation device (used at 33 (83%) centres), the Laerdal Infant Resuscitator the most popular model. Flow-inflating bags are used at 10 (25%) centres. The Neopuff Infant Resuscitator is used at 12 (30%) centres. Varying oxygen concentrations are provided during neonatal resuscitation at half of the centres, while 100% oxygen is routinely used at the other half. CONCLUSIONS: This survey shows considerable variation in practice, reflecting this lack of evidence and consequent uncertainty among clinicians. Comparison of the two most popular manual ventilation devices, the Laerdal Infant Resuscitator and the Neopuff Infant Resuscitator, is urgently required.
Cardiopulmonary Resuscitation↗
Devices and pressure sources for administration of nasal continuous positive airway pressure (NCPAP) in preterm neonates.
BACKGROUND: Nasal continuous positive airway pressure (NCPAP) is used to support preterm infants recently extubated, those experiencing significant apnoea of prematurity and those with respiratory distress soon after birth as an alternative to intubation and ventilation. This review will focus exclusively on identifying the most effective pressure source and interface for NCPAP delivery in preterm infants. OBJECTIVES: In preterm infants extubated to NCPAP following intermittent positive pressure ventilation (IPPV) for respiratory distress syndrome (RDS) or in those treated with NCPAP soon after birth, which technique of pressure generation and which type of nasal interface for NCPAP delivery most effectively reduces the need for additional respiratory support? SEARCH STRATEGY: The strategy included searches of MEDLINE (1966-2002), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2002), CINAHL, abstracts from conference proceedings, cross-referencing of previous reviews and the use of expert informants. SELECTION CRITERIA: Randomised or quasi-randomised trials comparing different techniques of NCPAP pressure generation and/or nasal interfaces in preterm infants extubated to NCPAP following IPPV for RDS or treated with NCPAP soon after birth. DATA COLLECTION AND ANALYSIS: Data was extracted and analysed by the first three authors. Dichotomous results were analysed using the relative risk (RR), risk difference (RD) and number needed to treat (NNT). MAIN RESULTS: 1. Preterm infants being extubated to NCPAP following a period of IPPV for RDS: Meta-analysis of the results from Davis 2001 and Roukema 1999a demonstrated that short binasal prongs are more effective at preventing re-intubation than single nasal or nasopharyngeal prongs [typical RR 0.59 (CI: 0.41, 0.85), typical RD -0.21 (CI: -0.35, -0.07), NNT 5 (CI: 3, 14)]. In the single study comparing short binasal prong devices (Sun 1999) the re-intubation rate was significantly lower with the Infant Flow Driver than with the Medicorp prong [RR 0.33 (CI: 0.17, 0.67), RD -0.32 (CI: -0.49, -0.15), NNT 3 (CI: 2, 7)]. 2. Preterm infants primarily treated with NCPAP soon after birth: The one trial identified, Mazzella 2001, found a significantly lower oxygen requirement and respiratory rate in those randomised to short binasal prongs when compared with CPAP delivered via nasopharyngeal prong. The requirement for intubation beyond 48 hours from randomisation was not assessed. No studies comparing different techniques of pressure generation were identified. REVIEWER'S CONCLUSIONS: Short binasal prong devices are more effective than single prongs in reducing the rate of re-intubation. Although the Infant Flow Driver appears more effective than Medicorp prongs the most effective short binasal prong device remains to be determined. The improvement in respiratory parameters with short binasal prongs suggests they are more effective than nasopharyngeal CPAP in the treatment of early RDS. Further studies incorporating longer-term outcomes are required. Studies are also needed to determine the optimal pressure source for the delivery of NCPAP.
Humans↗
In vitro comparison of nasal continuous positive airway pressure devices for neonates.
OBJECTIVE: To compare the resistance in vitro of different devices used for the delivery of nasal continuous positive airway pressure (NCPAP) in neonates. DESIGN: Flows of 4-8 litres/min were passed through a selection of neonatal NCPAP devices (single prong, Duotube, Argyle prong, Hudson prong, Infant Flow Driver), and the resultant fall in pressure measured using a calibrated pressure transducer. RESULTS: The decrease in pressure (cm H(2)O) for each device (size in parentheses) at a constant flow of 6 litres/min was: Duotube: (2.5), 21; (3.0), 6.2; (3.5), 2.3; single prong: (2.5), 4.4; (3.0), 2.1; (3.5), 1.2; Argyle prong: (XS), 3.6; (S), 1.9; (L), 1.5; Hudson prong: (0), 3.1; (1), 1.8; (2), 0.6; (3), 0.4; (4), 0.3; Infant Flow Driver: (small), 0.3; (medium), -0.3; (large), -0.5. CONCLUSIONS: A large variation in the potential fall in pressure may occur in the clinical setting. Devices with short double prongs had the lowest resistance to flow. These results have implications in the selection of the optimal device/s for clinical application and for future comparisons in randomised trials of NCPAP in neonates.
Airway Resistance↗