Maintaining normothermia immediately after birth in preterm infants <34 weeks' gestation: A systematic review and meta-analysis

AIM

To evaluate delivery room (DR) interventions to prevent hypothermia and improve outcomes in preterm newborn infants <34 weeks' gestation.

METHODS

Medline, Embase, CINAHL and CENTRAL were searched till 22nd July 2022. Randomized controlled trials (RCTs), non-RCTs and quality improvement studies were considered. A random effects meta-analysis was performed, and the certainty of evidence was evaluated using GRADE guidelines.

RESULTS

DR temperature of ≥23 °C compared to standard care improved temperature outcomes without an increased risk of hyperthermia (low certainty), whereas radiant warmer in servo mode compared to manual mode decreased mean body temperature (MBT) (moderate certainty). Use of a plastic bag or wrap (PBW) improved normothermia (low certainty), but with an increased risk of hyperthermia (moderate certainty). Plastic cap improved normothermia (moderate certainty) and when combined with PBW improved MBT (low certainty). Use of a cloth cap decreased moderate hypothermia (low certainty). Though thermal mattress (TM) improved MBT, it increased risk of hyperthermia (low certainty). Heated-humidified gases (HHG) for resuscitation decreased the risk of moderate hypothermia and severe intraventricular hemorrhage (very low to low certainty). None of the interventions was shown to improve survival, but sample sizes were insufficient.

CONCLUSIONS

DR temperature of ≥23 °C, radiant warmer in manual mode, use of a PBW and a head covering is suggested for preterm newborn infants <34 weeks' gestation. HHG and TM could be considered in addition to PBW provided resources allow, in settings where hypothermia incidence is high. Careful monitoring to avoid hyperthermia is needed.

Effects of tactile stimulation on spontaneous breathing during face mask ventilation

OBJECTIVE

We sought to determine the effect of stimulation during positive pressure ventilation (PPV) on the number of spontaneous breaths, exhaled tidal volume (VTe), mask leak and obstruction.

DESIGN

Secondary analysis of a prospective, randomised trial comparing two face masks.

SETTING

Single-centre delivery room study.

PATIENTS

Newborn infants ≥34 weeks' gestation at birth.

METHODS

Resuscitations were video recorded. Tactile stimulations during PPV were noted and the timing, duration and surface area of applied stimulus were recorded. Respiratory flow waveforms were evaluated to determine the number of spontaneous breaths, VTe, leak and obstruction. Variables were recorded throughout each tactile stimulation episode and compared with those recorded in the same time period immediately before stimulation.

RESULTS

Twenty of 40 infants received tactile stimulation during PPV and we recorded 57 stimulations during PPV. During stimulation, the number of spontaneous breaths increased (median difference (IQR): 1 breath (0-3); p_adj<0.001) and VTe increased (0.5 mL/kg (-0.5 to 1.7), p_adj=0.028), whereas mask leak (0% (-20 to 1), p_adj=0.12) and percentage of obstructed inflations (0% (0-0), p_adj=0.14) did not change, compared with the period immediately prior to stimulation. Increased duration of stimulation (p_adj<0.001) and surface area of applied stimulus (p_adj=0.026) were associated with a larger increase in spontaneous breaths in response to tactile stimulation.

CONCLUSIONS

Tactile stimulation during PPV was associated with an increase in the number of spontaneous breaths compared with immediately before stimulation without a change in mask leak and obstruction. These data inform the discussion on continuing stimulation during PPV in term infants.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trial Registry (ACTRN12616000768493).

Extubation generates lung volume inhomogeneity in preterm infants

OBJECTIVE

To evaluate the feasibility of electrical impedance tomography (EIT) to describe the regional tidal ventilation (V_T) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process of extubation from invasive to non-invasive respiratory support.

DESIGN

Prospective observational study.

SETTING

Single-centre tertiary neonatal intensive care unit.

PATIENTS

Preterm infants born <32 weeks' gestation who were being extubated to nasal continuous positive airway pressure as per clinician discretion.

INTERVENTIONS

EIT measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 min after commencing nasal continuous positive applied pressure (nCPAP). Extubation and pressure settings were determined by clinicians.

MAIN OUTCOME MEASURES

Global and regional ΔEELV and ΔV_T, heart rate, respiratory rate and oxygen saturation were measured throughout.

RESULTS

Thirty infants of median (range) 2 (1, 21) days were extubated to a median (range) CPAP 7 (6, 8) cm H₂O. SpO₂/FiO₂ ratio was a mean (95% CI) 50 (35, 65) lower 20 min after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared with SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). V_T was increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned V_T to pre-extubation patterns.

CONCLUSIONS

EIT was able to describe the complex lung conditions occurring during extubation to nCPAP, specifically lung volume loss and greater use of the dorsal lung. EIT may have a role in guiding peri-extubation respiratory support.

Physiological responses to facemask application in newborns immediately after birth

OBJECTIVE

Application of a face mask may induce apnoea and bradycardia, possibly via the trigeminocardiac reflex (TCR). We aimed to describe rates of apnoea and bradycardia in term and late-preterm infants following facemask application during neonatal stabilisation and compare the effects of first facemask application with subsequent applications.

DESIGN

Subgroup analysis of a prospective, randomised trial comparing two face masks.

SETTING

Single-centre study in the delivery room PATIENTS: Infants>34 weeks gestational age at birth METHODS: Resuscitations were video recorded. Airway flow and pressure were measured using a flow sensor. The effect of first and subsequent facemask applications on spontaneously breathing infants were noted. When available, flow waveforms as well as heart rate (HR) were assessed 20 s before and 30 s after each facemask application.

RESULTS

In total, 128 facemask applications were evaluated. In eleven percent of facemask applications infants stopped breathing. The first application was associated with a higher rate of apnoea than subsequent applications (29% vs 8%, OR (95% CI)=4.76 (1.41-16.67), p=0.012). On aggregate, there was no change in median HR over time. In the interventions associated with apnoea, HR dropped by 38bpm [median (IQR) at time of facemask application: 134bpm (134-150) vs 96bpm (94-102) 20 s after application; p=0.25] and recovered within 30 s.

CONCLUSIONS

Facemask applications in term and late-preterm infants during neonatal stabilisation are associated with apnoea and this effect is more pronounced after the first compared with subsequent applications. Healthcare providers should be aware of the TCR and vigilant when applying a face mask to newborn infants.

TRIAL REGISTRATION NUMBER

ACTRN12616000768493.

Neonatal videolaryngoscopy as a teaching aid: the trainees' perspective

INTRODUCTION

Neonatal intubation is a challenging skill to acquire. A randomised controlled trial (RCT) found junior trainees had higher intubation success rates if their supervisor shared their airway view on a videolaryngoscope screen compared with intubations where the supervisor could not see the videolaryngoscope screen. The intubations in the trial were supervised by a group of experienced neonatologists who developed an intubation teaching package that aimed to be informative, consistent and supportive. We surveyed the trainees to assess their experiences of the intubation attempts.

METHODS

Trainees participating in the RCT completed questionnaires anonymously after each intubation attempt. Questionnaires used 5-point Likert scales and free comment sections. Quantitative analysis was performed using descriptive statistics. In a qualitative analysis, free comments were coded to identify central recurring themes.

RESULTS

Two hundred and six questionnaires were completed by 36 trainees. The majority reported that the guidance received during intubation was helpful, the postprocedure feedback was educational and their confidence levels were increased. Trainees appreciated a controlled environment and calm, consistent guidance. They found intubations in the delivery room, those involving unstable infants, large audiences and parental presence more stressful. Responses were positive whether the videolaryngoscope screen was visible or covered, emphasising the importance of consistent guidance. Overall, 16% of intubations were reported as intimidating.

CONCLUSION

The shared airway view offered by videolaryngoscopy was well received. In addition, taking measures to control the setting, with standardised guidance and feedback, improved confidence and created a more positive learning experience.

Outcomes following antenatal identification of hydrops fetalis: a single-centre experience from 2001 to 2012

OBJECTIVE

To describe the aetiologies and outcomes of pregnancies complicated by hydrops fetalis (HF).

STUDY DESIGN

Case series of all pregnancies complicated by HF managed at The Royal Women's Hospital (RWH), Melbourne, Australia, between 2001 and 2012. Multiple pregnancies, and cases where antenatal care was not provided at RWH were excluded. Cases were identified from neonatal and obstetric databases. Data were extracted from maternal and neonatal case files, electronic pathology and radiology reports, and obstetric and neonatal databases.

RESULTS

Over 12 years, 131 fetuses with HF with a median (IQR) gestational age (GA) at diagnosis of 24 (20-30) weeks were included in the analysis. There were 65 liveborn infants with a median (IQR) GA at birth of 33 (31-37) weeks and a median (IQR) birthweight Z-score of 1.4 (0.4-2.2). Overall survival from diagnosis was 27% (36/131) increasing to 55% (36/65) if born alive.

CONCLUSIONS

The perinatal mortality risk for fetuses and newborn infants with HF is high with important differences dependent on underlying diagnosis and the time at which counselling is provided. Clinicians need to be aware of the outcomes of both fetuses and neonates with this condition.

Pulseless electrical activity: a misdiagnosed entity during asphyxia in newborn infants?

BACKGROUND

The 2015 neonatal resuscitation guidelines added ECG as a recommended method of assessment of an infant's heart rate (HR) when determining the need for resuscitation at birth. However, a recent case report raised concerns about this technique in the delivery room.

OBJECTIVES

To compare accuracy of ECG with auscultation to assess asystole in asphyxiated piglets.

METHODS

Neonatal piglets had the right common carotid artery exposed and enclosed with a real-time ultrasonic flow probe and HR was continuously measured and recorded using ECG. This set-up allowed simultaneous monitoring of HR via ECG and carotid blood flow (CBF). The piglets were exposed to 30 min normocapnic alveolar hypoxia followed by asphyxia until asystole, achieved by disconnecting the ventilator and clamping the endotracheal tube. Asystole was defined as zero carotid blood flow and was compared with ECG traces and auscultation for heart sounds using a neonatal/infant stethoscope.

RESULTS

Overall, 54 piglets were studied with a median (IQR) duration of asphyxia of 325 (200-491) s. In 14 (26%) piglets, CBF, ECG and auscultation identified asystole. In 23 (43%) piglets, we observed no CBF and no audible heart sounds, while ECG displayed an HR ranging from 15 to 80/min. Sixteen (30%) piglets remained bradycardic (defined as HR of <100/min) after 10 min of asphyxia, identified by CBF, ECG and auscultation.

CONCLUSION

Clinicians should be aware of the potential inaccuracy of ECG assessment during asphyxia in newborn infants and should rather rely on assessment using a combination of auscultation, palpation, pulse oximetry and ECG.

Optimal human and system performance during neonatal resuscitation

Performance in the delivery of care to sick neonates in need of resuscitation has long been defined primarily in terms of the extent of the knowledge possessed and hands-on skill demonstrated by physicians and other healthcare professionals. This definition of performance in neonatal resuscitation is limited by its focus solely on the human beings delivering care and a perceived set of the requisite skills to do so. This manuscript will expand the definition of performance to include all of the skill sets that humans must use to resuscitate newborns as well as the often complex systems in which those humans operate while delivering that care. It will also highlight how the principles of human factors and ergonomics can be used to enhance human and system performance during patient care. Finally, it will describe the role of simulation and debriefing in the assessment of human and system performance.

Analysis of unsuccessful intubations in neonates using videolaryngoscopy recordings

OBJECTIVES

Neonatal intubation is a difficult skill to learn and teach. If an attempt is unsuccessful, the intubator and instructor often cannot explain why. This study aims to review videolaryngoscopy recordings of unsuccessful intubations and explain the reasons why attempts were not successful.

STUDY DESIGN

This is a descriptive study examining videolaryngoscopy recordings obtained from a randomised controlled trial that evaluated if neonatal intubation success rates of inexperienced trainees were superior if they used a videolaryngoscope compared with a laryngoscope. All recorded unsuccessful intubations were included and reviewed independently by two reviewers blinded to study group. Their assessment was correlated with the intubator's perception as reported in a postintubation questionnaire. The Cormack-Lehane classification system was used for objective assessment of laryngeal view.

RESULTS

Recordings and questionnaires from 45 unsuccessful intubations were included (15 intervention and 30 control). The most common reasons for an unsuccessful attempt were oesophageal intubation and failure to recognise the anatomy. In 36 (80%) of intubations, an intubatable view was achieved but was then either lost, not recognised or there was an apparent inability to correctly direct the endotracheal tube. Suctioning was commonly performed but rarely improved the view.

CONCLUSIONS

Lack of intubation success was most commonly due to failure to recognise midline anatomical structures. Trainees need to be taught to recognise the uvula and epiglottis and use these landmarks to guide intubation. Excessive secretions are rarely a factor in elective and premedicated intubations, and routine suctioning should be discouraged. Better blade design may make it easier to direct the tube through the vocal cords.

Physical stimulation of newborn infants in the delivery room

OBJECTIVE

Neonatal resuscitation guidelines recommend that newborn infants are stimulated to assist with the establishment of regular respirations. The mode, site of application and frequency of stimulations are not stipulated in these guidelines. The effectiveness of stimulation in improving neonatal transition outcomes is poorly described.

METHODS

We conducted a retrospective review of video recordings of neonatal resuscitation at a tertiary perinatal centre. Four different types of stimulation (drying, chest rub, back rub and foot flick) were defined a priori and the frequency and infant response were documented.

RESULTS

A total of 120 video recordings were reviewed. Seventy-five (63%) infants received at least one episode of stimulation and 70 (58%) infants were stimulated within the first minute after birth. Stimulation was less commonly provided to infants <30 weeks' gestation (median (IQR) number of stimulations: 0 (0-1)) than infants born ≥30 weeks' gestation (1 (1-3); p<0.001). The most common response to stimulation was limb movement followed by infant cry and facial grimace. Truncal stimulation (drying, chest rub, back rub) was associated with more crying and movement than foot flicks.

CONCLUSION

Less mature infants are stimulated less frequently compared with more mature infants and many very preterm infants do not receive any stimulation. Most infants were stimulated within the first minute as recommended in resuscitation guidelines. Rubbing the trunk may be most effective but this needs to be confirmed in prospective studies.

Lung ultrasound immediately after birth to describe normal neonatal transition: an observational study

OBJECTIVE

Lung ultrasound (LUS) has shown promise as a diagnostic tool for the evaluation of the newborn with respiratory distress. No study has described LUS during 'normal' transition. Our goal was to characterise the appearance of serial LUS in healthy newborns from the first minutes after birth until airway liquid clearance is achieved.

STUDY DESIGN

Prospective observational study.

SETTING

Single-centre tertiary perinatal centre in Australia.

PATIENTS

Of 115 infants born at ≥35 weeks gestational age, mean (SD) gestational age of 38^6/7 weeks±11 days, mean birth weight of 3380±555 g, 51 were delivered vaginally, 14 via caesarean section (CS) after labour and 50 infants via elective CS.

INTERVENTIONS

We obtained serial LUS videos via the right and left axillae at 1-10 min, 11-20 min and 1, 2, 4 and 24 hours after birth.

MAIN OUTCOME MEASURES

LUS videos were graded for aeration and liquid clearance according to a previously validated system.

RESULTS

We analysed 1168 LUS video recordings. As assessed by LUS, lung aeration and airway liquid clearance occurred quickly. All infants had an established pleural line at the first examination (median=2 (1-4) min). Only 14% of infants had substantial liquid retention at 10 min after birth. 49%, 78% and 100% of infants had completed airway liquid clearance at 2, 4 and 24 hours, respectively.

CONCLUSIONS

In healthy transitioning newborn infants, lung aeration and partial liquid clearance are achieved on the first minutes after birth with complete liquid clearance typically achieved within the first 4 hours of birth.

TRIAL REGISTRATION NUMBER

ANZCT 12615000380594.

The effect of skin-to-skin care on cerebral oxygenation during nasogastric feeding of preterm infants

AIM

To describe cerebral oxygenation during gavage feeding of preterm infants during incubator and skin-to-skin care.

METHODS

Further analysis of data from two crossover studies comparing cerebral oxygenation, heart rate and oxygen saturation during skin-to-skin care with incubator care. Data were analysed in three epochs; 10 minutes prefeed, during-feed and 10 minutes postfeed. Measurements from infants fed during incubator care were compared with those obtained during skin-to-skin care.

RESULTS

In 39 infants [median (IQR) 27.8 (26.1-30.0) weeks' gestation], there was no difference in cerebral oxygenation between pre-, during- and postfeed. Heart rate increased by three beats per minute postfeed compared with during-feed. Twenty infants received two gavage feeds, one feed in the incubator and another during skin-to-skin care. There was no difference in cerebral oxygenation and heart rate; peripheral oxygen saturation decreased by 3% during feeding whilst skin-to-skin care compared with feeding in the incubator.

CONCLUSION

Cerebral oxygenation remained stable before, during and after gavage feeding in an incubator and during skin-to-skin care. The small decrease in oxygen saturation whilst receiving gavage feeding during skin-to-skin care is unlikely to be clinically important, providing reassurance that preterm infants maintain physiological stability during skin-to-skin care.

Assessing the tongue colour of newly born infants may help to predict the need for supplemental oxygen in the delivery room

AIM

It takes several minutes for infants to become pink after birth. Preductal oxygen saturation (SpO2) measurements are used to guide the delivery of supplemental oxygen to newly born infants, but pulse oximetry is not available in many parts of the world. We explored whether the pinkness of an infant's tongue provided a useful indication that supplemental oxygen was required.

METHODS

This was a prospective observational study of infants delivered by Caesarean section. Simultaneous recording of SpO2 and visual assessment of whether the tongue was pink or not was made at 1-7 and 10 min after birth.

RESULTS

The 38 midwives and seven paediatric trainees carried out 271 paired assessments on 68 infants with a mean (SD) birthweight of 3214 (545) grams and gestational age of 38 (2) weeks. When the infant did not have a pink tongue, this predicted SpO2 of <70% with a sensitivity of 26% and a specificity of 96%.

CONCLUSION

Tongue colour was a specific but insensitive sign that indicated when SpO2 was <70%. When the tongue is pink, it is likely that an infant has an SpO2 of more than 70% and does not require supplemental oxygen.

Comparison of heart rate and oxygen saturation measurements from Masimo and Nellcor pulse oximeters in newly born term infants

AIM

To compare heart rate (HR) measurements from Masimo and Nellcor pulse oximeters (POs) against HR measured via a three lead electrocardiograph (ECG) (HRECG ). We also compared peripheral oxygen saturation (SpO2 ) measurements between Nellcor and Masimo oximeters.

METHOD

Term infants born via elective caesarean section were studied. ECG leads were placed on the infant's chest and abdomen. Masimo and Nellcor PO sensors were randomly allocated to either foot. The monitors were placed on a trolley, and data from each monitor screen captured by a video camera. HR, SpO2 measurements and signal quality were extracted. Bland-Altman analysis was used to determine agreement between HR from the ECG and each oximeter, and between SpO2 from the oximeters.

RESULTS

We studied 44 infants of whom 4 were resuscitated. More than 8000 pairs of observations were used for each comparison of HR and SpO2. The mean difference (±2SD) between HRECG and HRN ellcor was -0.8 (±11) beats per minute (bpm); between HRECG and HRM asimo was 0.2 (±9) bpm. The mean (±2SD) difference between SpO2Masimo and SpO2Nellcor was -3 (±15)%. The Nellcor PO measured 20% higher than the Masimo PO at SpO2 <70%.

CONCLUSION

Both oximeters accurately measure HR. There was good agreement between SpO2 measurements when SpO2 ≥70%. At lower SpO2 , agreement was poorer.

Variability of respiratory parameters and extubation readiness in ventilated neonates

BACKGROUND

A spontaneous breathing trial (SBT) has been used to guide suitability of extubation in VLBW infants. Respiratory variability (RV) has been used to assess extubation readiness in adults but was never investigated in preterms. The combination of a SBT and RV may further improve prediction of successful extubation.

STUDY DESIGN

Using data previously collected during the SBT, the following respiratory variables were analysed: inspiratory time (T(I)), expiratory time (T(E)), T(I)/total breath time, tidal volume (V(T)) and mean inspiratory flow (V(T)/T(I)). RV was quantified using time-domain analysis for each respiratory variable and expressed as a variability index (VI). The sensitivity, specificity, positive and negative predictive values (PPV and NPV) of the SBT, each VI and combined SBT+VI were calculated. Extubation failure was defined as need of re-intubation within 72 h.

RESULTS

A total of 44 infants were included. Successfully (n=36) and unsuccessfully (n=8) extubated infants had similar baseline characteristics and number of breaths analysed. VI for V(T)/T(I)was significantly decreased in the failure group. The combination of the SBT and VI of either T(I)or V(T)were the most accurate predictors of successful extubation with a sensitivity of 100% and specificity of 75% and a PPV and NPV for extubation success of 95% and 100%, respectively.

CONCLUSIONS

A significant decrease in V(T)/T(I)variability occurred in infants requiring re-intubation. The combination of a SBT failure and decreased variability in T(I)or V(T)was highly predictive of failure. This combination is promising but requires prospective evaluation in a larger population.

Determining the best method of Nellcor pulse oximeter sensor application in neonates

AIM

To identify the optimal sensor application method that gave the quickest display of accurate heart rate (HR) data using the Nellcor OxiMax N-600x pulse oximeter (PO).

METHODS

Stable infants who were monitored with an electrocardiograph were included. Three sensor application techniques were studied: (i) sensor connected to cable, then applied to infant; (ii) sensor connected to cable, applied to investigator's finger, and then to infant; (iii) sensor applied to infant, then connected to cable. The order of techniques tested was randomized for each infant. Time taken to apply the PO sensor, to display data and to display accurate data (HR(PO) = HR(ECG) ± 3 bpm) were recorded using a stopwatch.

RESULTS

Forty infants were studied [mean (SD) birthweight, 1455 (872) g; gestational age, 31 (4) weeks; post-menstrual age, 34 (4) weeks]. Method 3 acquired any data significantly faster than methods 1 (p = 0.013; CI, -9.6 to -3.0 sec) and 2 (p = 0.004; CI, -5.9 to -1.2 sec). Method 3 acquired accurate data significantly faster than method 1 (p = 0.016; CI, -9.4 to -1.0 sec), but not method 2 (p = 0.28).

CONCLUSION

Applying the sensor to the infant before connecting it to the cable yields the fastest acquisition of accurate HR data from the Nellcor PO.

Changes in heart rate in the first minutes after birth

The normal range of heart rate (HR) in the first minutes after birth has not been defined. Objective To describe the HR changes of healthy newborn infants in the delivery room (DR) detected by pulse oximetry. Study Design All inborn infants were eligible and included if a member of the research team attended the birth. Infants were excluded if they received any form of medical intervention in the DR including supplemental oxygen, or respiratory support. HR was measured using a pulse oximeter (PO) with the sensor applied to the right hand or wrist immediately after birth. PO data (oxygen saturation, HR and signal quality) were downloaded every 2 sec and analysed only when the signal had no alarm messages (low IQ signal, low perfusion, sensor off, ambient light). Results Data from 468 infants with 61 650 data points were included. Infants had a mean (range) gestational age of 38 (25-42) weeks and birth weight 2970 (625-5135) g. At 1 min the median (IQR) HR was 96 (65-127) beats per min (bpm) rising at 2 min and 5 min to 139 (110-166) bpm and 163 (146-175) bpm respectively. In preterm infants, the HR rose more slowly than term infants. Conclusions The median HR was <100 bpm at 1 min after birth. After 2 min it was uncommon to have a HR <100 bpm. In preterm infants and those born by caesarean section the HR rose more slowly than term vaginal births.

Oral continuous positive airway pressure (CPAP) following nasal injury in a preterm infant

Non-invasive respiratory support is increasingly popular but is associated with complications including nasal trauma. The present report describes a novel method of oral continuous positive airway pressure (CPAP) delivery in an extremely premature infant with severe nasal septum erosion. The distal end of a cut down endotracheal tube was passed through a small hole made in the teat of a dummy (infant pacifier) and sutured in place. The dummy was secured in the infant's mouth and CPAP was delivered to the pharynx. The device was well tolerated and the infant was successfully managed using this technique for 48 days, avoiding endotracheal intubation and ventilation.

Assist control volume guarantee ventilation during surfactant administration

OBJECTIVE

To measure changes in ventilator parameters in preterm infants receiving surfactant during assist control volume guarantee (AC/VG) ventilation.

METHODS

22 preterm infants (up to 32 weeks' gestation) receiving surfactant for respiratory distress syndrome were enrolled in a prospective study of ventilator parameters during AC/VG ventilation at a tertiary neonatal intensive care unit. Ventilator pressures, flow and tidal volume waveforms were recorded from the Dräger Babylog 8000 plus in real time, and compared to pre-surfactant measurements.

RESULTS

Following surfactant administration, 21 of 22 babies experienced completely obstructed endotracheal gas flow. Peak inflation pressure (PIP) increased by a median (IQR) of 8 (4-10) cm H2O, and took 30-60 min to return to baseline. Inspired oxygen concentration was reduced from a median (IQR) of 39% (26%-44%) to 26% (21%-30%) in the first 5 min. The set maximum PIP (Pmax) limited the delivered PIP such that most babies received tidal volumes less than the target value (V(Ttarget)) immediately following surfactant delivery. Four infants, in a subgroup of 11 infants where Pmax was set to less than 10 cm H2O above baseline PIP, were still receiving <90% of V(Ttarget) 20 min post surfactant.

CONCLUSIONS

When giving surfactant during AC/VG ventilation, complete obstruction is common. PIPs increased and remain elevated for 30-60 min. The Pmax setting may restrict tidal volume delivery.

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 (Spo(2)) and heart rate (HR) in the first 10 min after birth in very preterm infants initially resuscitated with 100% oxygen (OX(100)) or air (OX(21)).

PATIENTS AND METHODS

In July 2006, policy changed from using 100% oxygen to air. Observations of Spo(2) 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 OX(100) group and 106 in the OX(21) group. In the OX(100) group, Spo(2) had risen to a median of 84% after 2 min and 94% by 5 min. In the OX(21) group, median Spo(2) was 31% at 2 min and 54% at 5 min. In the OX(21) group, 92% received supplemental oxygen at a median of 5 min; the Spo(2) rose to a median of 81% by 6 min. In the first 10 min after birth, 80% and 55% of infants in the OX(100) and OX(21) groups, respectively, had an Spo(2) > or =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 Spo(2) resulted in a similar course to "normal" term and preterm infants. Of the infants resuscitated with 100% oxygen, 80% had Spo(2) > or =95% during the first 10 min. The HR changes in the two groups were very similar.

Volume-guarantee ventilation: pressure may decrease during obstructed flow

BACKGROUND

Two unexpected observations were made during ventilation with the Dräger Babylog 8000+ in volume-guarantee mode: (a) during complete obstruction to gas flow down the endotracheal tube (ETT), positive inspiratory pressure (PIP) was reduced to half way between the maximum inflating pressure and the positive end expiratory pressure (PEEP) even though the set expired tidal volume had not been achieved; (b) an external Dräger waveform monitor may stop displaying real-time waveforms when a tube-obstructed alarm is activated.

OBJECTIVE

To investigate these phenomena using a test lung.

METHOD

A 50 ml Dräger test lung was attached to the ventilation circuit of a Dräger Babylog 8000+. Partial obstruction to ETT flow was induced by compressing the tubing leading to the test lung, and complete obstruction was achieved by clamping. Recordings were made from the digital output of the ventilator at 125 Hz.

RESULTS

When the ETT flow was completely obstructed during VG ventilation, a constant PIP was set midway between the set maximum and PEEP. This did not happen during partial obstruction. The external waveform monitor display froze when ETT flow was completely obstructed.

CONCLUSIONS

During complete ETT obstruction, the PIP is set to a pressure midway between maximum PIP and PEEP even if this is less than the PIP used before the obstruction. Further research is needed to evaluate whether this reduction in PIP is associated with prolongation of precipitating events.

A trial of spontaneous breathing to determine the readiness for extubation in very low birth weight infants: a prospective evaluation

Extubation failure in premature infants is common. A spontaneous breathing trial (SBT) was prospectively evaluated to determine timing of extubation. Compared with historical controls, infants were extubated at significantly higher ventilator rates and airway pressures using the SBT. No differences in rates of bronchopulmonary dysplasia or duration of ventilation were seen.

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.

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.

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.