Jennifer A Dawson

Defining the reference range for oxygen saturation for infants after birth.

OBJECTIVE: The goal was to define reference ranges for pulse oxygen saturation (Spo2) values in the first 10 minutes after birth for infants who received no medical intervention in the delivery room. METHODS: Infants were eligible if a member of the research team was available to record Spo2 immediately after birth. Infants were excluded if they received supplemental oxygen or any type of assisted ventilation. Spo2 was measured with a sensor applied to the right hand or wrist as soon as possible after birth; data were collected every 2 seconds. RESULTS: We studied 468 infants and recorded 61650 Spo2 data points. The infants had a mean ± SD gestational age of 38 ± 4 weeks and birth weight of 2970 ± 918 g. For all 468 infants, the 3rd, 10th, 50th, 90th, and 97th percentile values at 1 minute were 29%, 39%, 66%, 87%, and 92%, respectively, those at 2 minutes were 34%, 46%, 73%, 91%, and 95%, and those at 5 minutes were 59%, 73%, 89%, 97%, and 98%. It took a median of 7.9 minutes (interquartile range: 5.0–10 minutes) to reach a Spo2 value of >90%. Spo2 values for preterm infants increased more slowly than those for term infants. We present percentile charts for all infants, term infants of ≥37 weeks, preterm infants of 32 to 36 weeks, and extremely preterm infants of <32 weeks. CONCLUSION: These data represent reference ranges for Spo2 in the first 10 minutes after birth for preterm and term infants.

Oxygen saturation and heart rate during delivery room resuscitation of infants <30 weeks gestation with air or 100% oxygen.

Background: Because of concerns about harmful effects of 100% oxygen on newborn infants, air has started to be used for resuscitation in the delivery room. Objective: To describe changes in preductal oxygen saturation (Spo2) and heart rate (HR) in the first 10 min after birth in very preterm infants initially resuscitated with 100% oxygen (OX100) or air (OX21). Patients and methods: In July 2006, policy changed from using 100% oxygen to air. Observations of Spo2 and HR before and after the change were recorded whenever a member of the research team was available to attend the birth. Results: There were 20 infants in the OX100 group and 106 in the OX21 group. In the OX100 group, Spo2 had risen to a median of 84% after 2 min and 94% by 5 min. In the OX21 group, median Spo2 was 31% at 2 min and 54% at 5 min. In the OX21 group, 92% received supplemental oxygen at a median of 5 min; the Spo2 rose to a median of 81% by 6 min. In the first 10 min after birth, 80% and 55% of infants in the OX100 and OX21 groups, respectively, had an Spo2 ⩾95%. Increases in HR over the first 10 min were very similar in the two groups. Conclusions: Most very preterm infants received supplemental oxygen if air was used for the initial resuscitation. In these infants, the use of backup 100% oxygen and titration against Spo2 resulted in a similar course to “normal” term and preterm infants. Of the infants resuscitated with 100% oxygen, 80% had Spo2 ⩾95% during the first 10 min. The HR changes in the two groups were very similar.

Improved techniques reduce face mask leak during simulated neonatal resuscitation: Study 2

Background: Techniques of positioning and holding neonatal face masks vary. Studies have shown that leak at the face mask is common and often substantial irrespective of operator experience. Aims: (1) To identify a technique for face mask placement and hold which will minimise mask leak. (2) To investigate the effect of written instruction and demonstration of the identified technique on mask leak for two round face masks. Method: Three experienced neonatologists compared methods of placing and holding face masks to minimise the leak for Fisher & Paykel 60 mm and Laerdal size 0/1 masks. 50 clinical staff gave positive pressure ventilation to a modified manikin designed to measure leak at the face mask. They were provided with written instructions on how to position and hold each mask and then received a demonstration. Face mask leak was measured after each teaching intervention. Results: A technique of positioning and holding the face masks was identified which minimised leak. The mean (SD) mask leaks before instruction, after instruction and after demonstration were 55% (31), 49% (30), 33% (26) for the Laerdal mask and 57% (25), 47% (28), 32% (30) for the Fisher & Paykel mask. There was no significant difference in mask leak between the two masks. Written instruction alone reduced leak by 8.8% (CI 1.4% to 16.2%) for either mask; when combined with a demonstration mask leak was reduced by 24.1% (CI 16.4% to 31.8%). Conclusion: Written instruction and demonstration of the identified optimal technique resulted in significantly reduced face mask leak.

Respiratory Function Monitor Guidance of Mask Ventilation in the Delivery Room: A Feasibility Study

OBJECTIVE To investigate whether using a respiratory function monitor (RFM) during mask resuscitation of preterm infants reduces face mask leak and improves tidal volume (V(T)). STUDY DESIGN Infants receiving mask resuscitation were randomized to have the display of an RFM (airway pressure, flow, and V(T) waves) either visible or masked. RESULT Twenty-six infants had the RFM visible, and 23 had the RFM masked. The median mask leak was 37% (IQR, 21%-54%) in the visible RFM group and 54% (IQR, 37%-82%) in the masked RFM group (P = .01). Mask repositioning was done in 19 infants (73%) of the visible group and in 6 infants (26%) of the masked group (P = .001). The median expired V(T) was similar in the 2 groups. Oxygen was provided to 61% of the visible RFM group and 87% of the RFM masked group (P = .044). Continuous positive airway pressure use was greater in the visible RFM group (73% vs 43%; P = .035). Intubation in the delivery room was done in 21% of the visible group and in 57% of the masked group (P = .035). CONCLUSION Using an RFM was associated with significantly less mask leak, more mask adjustments, and a lower rate of excessive V(T).

Respiratory monitoring of neonatal resuscitation

Video observations and recordings of respiratory signals from mannequin studies and delivery room (DR) resuscitations are described. This article discusses the uses of a respiratory function monitor (RFM) during training and resuscitations along with potential pitfalls and limitations. It adds objectivity to the clinical assessment. A respiratory function monitor provides real-time quantitative information including tidal volume and leak. It may be used to teach correct mask hold and positioning techniques during simulation-based mannequin. Examples demonstrating its potential usefulness during resuscitations are provided. However, further studies are needed to investigate whether it can help improve short-term and long-term outcomes.

Breathing Patterns in Preterm and Term Infants Immediately After Birth

There is limited data describing how preterm and term infants breathe spontaneously immediately after birth. We studied spontaneously breathing infants ≥29 wk immediately after birth. Airway flow and tidal volume were measured for 90 s using a hot wire anemometer attached to a facemask. Twelve preterm and 13 term infants had recordings suitable for analysis. The median (interquartile range) proportion of expiratory braking was very high in both groups (preterm 90 [74–99] vs. term 87 [74–94]%; NS). Crying pattern was the predominant breathing pattern for both groups (62 [36–77]% vs. 64 [46–79]%; NS). Preterm infants showed a higher incidence of expiratory hold pattern (9 [4–17]% vs. 2 [0–6]%; p = 0.02). Both groups had large tidal volumes (6.7 [3.9] vs. 6.5 [4.1] mL/kg), high peak inspiratory flows (5.7 [3.8] vs. 8.0 [5] L/min), lower peak expiratory flow (3.6 [2.4] vs. 4.8 [3.2] L/min), short inspiration time (0.31 [0.13] vs. 0.32 [0.16] s) and long expiration time (0.93 [0.64] vs. 1.14 [0.86] s). Directly after birth, both preterm and term infants frequently brake their expiration, mostly by crying. Preterm infants use significantly more expiratory breath holds to defend their lung volume.

Pulse oximetry for monitoring infants in the delivery room: a review

During the first few minutes of life, oxygen saturation (saturation by pulse oximetry, SpO2) increases from intrapartum levels of 30–40%.1 In algorithms for neonatal resuscitation published by the International Liaison Committee for Resuscitation,2 European Resuscitation Council3 and Australian Resuscitation Council,4 clinical assessment of an infant’s colour (a measure of oxygenation) and heart rate are used as major action points. However, studies have shown that clinical assessment of colour during neonatal transition is unreliable.5,6 O’Donnell et al 6 showed that the SpO2 at which observers perceived infants to be pink varied widely, ranging from 10% to 100%. Assessing colour is difficult and therefore is a poor proxy for tissue oxygenation during the first few minutes of life. Kattwinkel7 suggested pulse oximetry may help achieve normoxia in the delivery room. The American Heart Association8 suggests that “administration of a variable concentration of oxygen guided by pulse oximetry may improve the ability to achieve normoxia more quickly”. Although “normoxia” and an acceptable time to achieve this during neonatal transition have not been defined, Leone and Finer9 advocate a target “SpO2 of 85 to 90% by three minutes after birth for all infants except in special circumstances”—for example, diaphragmatic hernia or cyanotic congenital heart disease. International surveys show that oximetry is increasingly used during neonatal resuscitation.10,11 To date, there are no evidence-based guidelines for using oximetry to measure an infant’s SpO2 and to guide interventions during neonatal transition after birth. We reviewed the literature to evaluate the evidence on the use of SpO2 measurements immediately after birth. Pulse oximetry measures SpO2 continuously and non-invasively, without the need for calibration, and correlates closely with arterial oxygen saturation.12 Pulse oximetry is based on the red and infrared light-absorption …

Effect of sustained inflation duration; resuscitation of near-term asphyxiated lambs

Objective The 2010 ILCOR neonatal resuscitation guidelines do not specify appropriate inflation times for the initial lung inflations in apnoeic newborn infants. The authors compared three ventilation strategies immediately after delivery in asphyxiated newborn lambs. Design Experimental animal study. Setting Facility for animal research. Subjects Eighteen near-term lambs (weight 3.5–3.9 kg) delivered by caesarean section. Interventions Asphyxia was induced by occluding the umbilical cord and delaying ventilation onset (10–11 min) until mean carotid blood pressure (CBP) was ≤22 mm Hg. Animals were divided into three groups (n=6) and ventilation started with: (1) inflation times of 0.5 s at a ventilation rate 60/min, (2) five 3 s inflations or (3) a single 30 s inflation. Subsequent ventilation used inflations at 0.5 s at 60/min for all groups. Main outcome measures Times to reach a heart rate (HR) of 120 bpm and a mean CBP of 40 mm Hg. Secondary outcome was change in lung compliance. Results Median time to reach HR 120 bpm and mean CBP 40 mm Hg was significantly shorter in the single 30 s inflation group (8 s and 74 s) versus the 5×3 s inflation group (38 s and 466 s) and the conventional ventilation group (64 s and 264 s). Lung compliance was significantly better in the single 30 s inflation group. Conclusion A single sustained inflation of 30 s immediately after birth improved speed of circulatory recovery and lung compliance in near-term asphyxiated lambs. This approach for neonatal resuscitation merits further investigation.

Compliance With Alarm Limits for Pulse Oximetry in Very Preterm Infants

OBJECTIVE. The objective of this study was to determine the rate of compliance with hospital guidelines for alarm limits for pulse oximetry in preterm infants on oxygen therapy. METHODS. All infants admitted to the nurseries at the Royal Womens Hospital, Melbourne, Australia, with gestational age <32 weeks or birth weight <1500 g between August 2005 and February 2006 were eligible for inclusion. Data on the alarm limits set for infants on oxygen therapy were collected prospectively. The target saturation range recommended in written hospital guidelines was 88% to 92%, with alarm limits set at 85% and 94%. RESULTS. Data were prospectively collected for 144 subjects with mean (SD) gestational age 29.3 (2.4) weeks and birth weight 1226 (354) g; 1073 alarm limits were collected when infants were on oxygen. The lower alarm limit was set correctly 91.1% of the time. In contrast, the upper alarm limit was set correctly only 23.3% of the time: 76.5% of the time it was too high, and 23.8% of the time it was set at 100%. Infants with an upper alarm limit set correctly on a particular day had a significantly lower birth weight, gestational age, postmenstrual age, and postnatal age than infants who had the upper alarm limit set too high. Use of assisted ventilation, higher inspired oxygen concentrations, and more frequent changes in inspired oxygen concentration were all associated with improved odds of having an appropriately set upper alarm limit. CONCLUSIONS. This study suggests that current guidelines regarding the upper pulse oximeter alarm limit for infants receiving oxygen might be commonly exceeded, although compliance might be better for infants at higher risk of adverse outcomes. However, there might be less variation from guidelines for the lower alarm limit.

Oxygenation with T-Piece versus Self-Inflating Bag for Ventilation of Extremely Preterm Infants at Birth: A Randomized Controlled Trial

OBJECTIVE To investigate whether infants < 29 weeks gestation who receive positive pressure ventilation (PPV) immediately after birth with a T-piece have higher oxygen saturation (SpO₂) measurements at 5 minutes than infants ventilated with a self inflating bag (SIB). STUDY DESIGN Randomized, controlled trial of T-piece or SIB ventilation in which SpO₂ was recorded immediately after birth from the right hand/wrist with a Masimo Radical pulse oximeter, set at 2-second averaging and maximum sensitivity. All resuscitations started with air. RESULTS Forty-one infants received PPV with a T-piece and 39 infants received PPV with a SIB. At 5 minutes after birth, there was no significant difference between the median (interquartile range) SpO₂ in the T-piece and SIB groups (61% [13% to 72%] versus 55% [42% to 67%]; P = .27). More infants in the T-piece group received oxygen during delivery room resuscitation (41 [100%] versus 35 [90%], P = .04). There was no difference in the groups in the use of continuous positive airway pressure, endotracheal intubation, or administration of surfactant in the delivery room. CONCLUSION There was no significant difference in SpO₂ at 5 minutes after birth in infants < 29 weeks gestation given PPV with a T-piece or a SIB as used in this study.