Biomedical subjects
Publications and source records attributed to Peter G Davis.
Resuscitation guidelines recommend administration of free-flow oxygen to newly born infants who breathe but remain cyanosed. Self-inflating resuscitation bags are described as unreliable for this purpose. We measured oxygen concentrations >or=80% delivered through a 240 mL Laerdal self-inflating resuscitation bag and from 5 mm tubing inside a cupped hand.
Heart rate (HR) dictates intervention during neonatal resuscitation. Guidelines recommend that HR be assessed by auscultation or palpation. We compared HRs determined clinically with electrocardiography (ECG) in healthy newborns in the delivery room. Clinical assessment by 23 observers randomly allocated to assess HR by one of two methods in 26 infants, was found to be inaccurate and underestimate ECG HR. The mean difference between HR assessed by auscultation and palpation ECG and HR using methodology recommended by the Neonatal Resuscitation Programme was 14 and 22 beats per minute respectively.
OBJECTIVE: Because the optimal concentration of oxygen (FiO2) required for stabilization of the newly born infant has not been established, the FiO2 is commonly adjusted according to the infant's oxygen saturation (SpO2). We aimed to determine the range of pre-ductal SpO2 in the first minutes of life in healthy newborn infants. STUDY DESIGN: We applied an oximetry sensor to the infant's right palm or wrist of term and preterm deliveries immediately after birth. Infants who received any resuscitation or supplemental oxygen were excluded. SpO2 was recorded at 60 second intervals for at least 5 minutes and until the SpO2 was >90%. RESULTS: A total of 205 deliveries were monitored; 30 infants were excluded from the study. SpO2 readings were obtained within 60 seconds of age from 92 of 175 infants (53%). The median (interquartile range) SpO2 at 1 minute was 63% (53%-68%). There was a gradual rise in SpO2 with time, with a median SpO2 at 5 minutes of 90% (79%-91%). CONCLUSION: Many newborns have an SpO2 <90% during the first 5 minutes of life. This should be considered when choosing SpO2 targets for infants treated with supplemental oxygen in the delivery room.
OBJECTIVES: To assess interobserver variability of Apgar scores assigned with video recordings of neonatal resuscitation (AS(video)) and compare the scores assigned by observers of videos to the Apgar score given by staff attending the delivery (AS(del)). STUDY DESIGN: Ten-second clips of 30 newborns taken at 5 minutes were shown to observers. Infants were 23 to 40 weeks' gestation, received varying degrees of resuscitation, and were monitored with pulse oximetry. Forty-two observers (neonatal/obstetric medical/nursing staff) scored infants' respiratory effort, muscle tone, reflex irritability, and color. The value for heart rate was assigned from the oximeter, which was masked in all clips. All 42 AS(video) and the AS(del) were represented graphically for each infant. Interobserver reliability was assessed by use of a variance components model. RESULTS: AS(video) varied widely between observers. Variability was large for all 4 elements of the score observers assigned and was seen irrespective of the infant's level of illness. AS(del) was greater than AS(video) in most cases, on average by 2.4 points. There was no evidence that the level of discrepancy was substantially different between groupings of staff. CONCLUSION: The Apgar score has poor interobserver reliability. More objective and precise measures of newborns' condition are required.
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OBJECTIVE: Postnatal corticosteroid therapy is controversial. The aim of this study was to determine the short-term effects of low-dose dexamethasone treatment among chronically ventilator-dependent neonates. METHODS: Very preterm (gestational age: <28 weeks) or extremely low birth weight (birth weight: <1000 g) infants who were ventilator dependent after the first 1 week of life were eligible and were assigned randomly to receive masked dexamethasone (0.89 mg/kg over 10 days) or saline placebo. Data on ventilator and oxygen requirements and deaths were recorded. RESULTS: Seventy infants were recruited from 11 centers, at a median age of 23 days. More infants were extubated successfully by 10 days of treatment in the dexamethasone group (60%, 21 of 35 patients) than in the control group (12%, 4 of 34 patients) (odds ratio [OR]: 11.2; 95% confidence interval [CI]: 3.2-39.0). Ventilator and oxygen requirements improved substantially, and the duration of intubation was shorter. There was little evidence for a reduction in either the mortality rate (dexamethasone group: 11%; control group: 20%; OR: 0.52; 95% CI: 0.14-1.95) or the rate of oxygen dependence at 36 weeks (dexamethasone group: 85%; control group: 91%; OR: 0.58; 95% CI: 0.13-2.66). There were no obvious effects of low-dose dexamethasone on blood glucose concentrations, blood pressure, or other complications. No infant experienced intestinal perforation. CONCLUSIONS: Low-dose dexamethasone treatment after the first 1 week of life clearly facilitates extubation and shortens the duration of intubation among ventilator-dependent, very preterm/extremely low birth weight infants, without any obvious short-term complications. Combined with recent evidence that infants at very high risk of bronchopulmonary dysplasia may benefit in the long term, our study reopens debate regarding the role of low-dose, late postnatal, corticosteroid therapy.
OBJECTIVE: Endotracheal intubation of newborn infants is a mandatory competence for many pediatric trainees. The Neonatal Resuscitation Program recommends a 20-second limit for intubation attempts. Intubation attempts by junior doctors are frequently unsuccessful, and many infants are intubated between 20 and 30 seconds without apparent adverse effect. Little is known about the proficiency of more senior medical staff, the time taken to determine endotracheal tube (ETT) position, or the effects of attempted intubation on infants' heart rate (HR) and oxygen saturation (Spo2) in the delivery room (DR). The objectives of this study were to determine (1) the success rates and duration of intubation attempts during DR resuscitation, (2) whether experience is associated with greater success rates and shorter time taken to intubate, (3) the time taken to identify ETT position after intubation, and (4) the frequency with which infants deteriorated during intubation attempts and the time at which this occurred. METHODS: We reviewed videos of DR resuscitations; identified whether intubation was attempted; and, when attempted, whether intubation was attempted by a resident, a fellow, or a consultant. We defined the duration of an intubation attempt as the time from the introduction of the laryngoscope blade to the mouth to its removal, regardless of whether an ETT was introduced. We determined the time from removal of the laryngoscope to the clinicians' decision as to whether the intubation was successful and noted the basis on which this decision was made (clinical assessment, flow signals, or exhaled carbon dioxide [ETCO2] detection). We determined success according to clinical signs in all cases and used flow signals that were obtained during ventilation via the ETT or ETCO2 when available. When neither was available, the chest radiograph on admission to the NICU was reviewed. For infants who were monitored with pulse oximetry, we determined their HR and Spo2 before the intubation attempt. We then determined whether either or both fell by > or =10% during the attempt and, if so, at what time it occurred. RESULTS: We reviewed 122 video recordings in which orotracheal intubation was attempted 60 times in 31 infants. We secondarily verified ETT position using flow signals, ETCO2, or chest radiographs after 94% of attempts in which an ETT was introduced. Thirty-seven (62%) attempts were successful. Success rates and mean (SD) time to intubate successfully by group were as follows: residents: 24%, 49 seconds (13 seconds); fellows: 78%, 32 seconds (13 seconds); and consultants: 86%, 25 seconds (17 seconds). Of the 23 unsuccessful attempts, 13 were abandoned without an attempt to pass an ETT and 10 were placed incorrectly. The time to determine ETT position in the DR was longer when clinical assessment alone was used. Infants who were monitored with oximetry deteriorated during nearly half of the intubation attempts. Deterioration seemed more likely when HR and Spo2 were low before the attempt. CONCLUSIONS: Intubation attempts often are unsuccessful, and successful attempts frequently take >30 seconds. Greater experience is associated with greater success rates and shorter duration of successful attempts. Flow signals and ETCO2 may be useful in determining ETT position more quickly than clinical assessment alone. Infants frequently deteriorate during intubation attempts. Improved monitoring of infants who are resuscitated in the DR is desirable.
The Neonatal Review Group of the Cochrane Collaboration is dedicated to improving outcomes of newborn infants through the collection and synthesis of the highest quality evidence. Much has been achieved with limited resources. Future challenges for the group are to maintain and extend current reviews of therapeutic interventions, to develop bridging reviews to assist clinicians in applying current evidence more easily, to expand the scope of the Cochrane Library to include diagnostic tests, and to utilize techniques such as prospective meta-analysis to answer remaining questions in the field. In future, the Neonatal Review Group needs to assist reviewers in developing countries to prepare reviews relevant to their settings that will reduce the global burden of neonatal mortality and morbidity.
Clinical assessment and end-tidal carbon dioxide (ETCO2) detectors are used to verify tracheal intubation in newborn infants. A case is presented in which an ETCO2 detector was misleading in determining endotracheal tube (ETT) position but useful in determining the efficacy of ventilation in an extremely preterm infant.
Application of the sensor to newly born infants before connection to a pulse oximeter increases the reliability and speed with which data are displayed. Data are available in most infants within 90 seconds of birth. Oximetry may be useful in guiding interventions during resuscitation.
OBJECTIVE: To study the frequency and types of adverse reactions to currently available vaccines in very preterm infants. METHODS: Case notes were obtained for very preterm infants < or =30 weeks' gestational age who received their first immunization at the Royal Women's Hospital, Melbourne, during 1999-2003. Data were extracted for the time periods 48 h before and 48 h after immunizations, with the data extraction blinded as to whether the period being evaluated was pre- or post-immunization. Data collected focused on the frequency and severity of apnoea, respiratory support, fever and clinical consequences of adverse reactions. RESULTS: A total of 48 very preterm infants were immunized during the period; 37 infants had Comvax (Haemophilus influenzae type B and hepatitis B vaccine), Infanrix (diphtheria, tetanus and acellular pertussis vaccine) and inactivated poliomyelitis vaccine, and 11 infants had Comvax and Infanrix only. Their mean (SD) gestational age at birth was 26.4 (1.7) weeks with mean birthweight of 872 (235) g. The mean postnatal age at immunization was 76 (20) days. Low-grade fever (>37.5 degrees C per axilla) occurred in 16 (33%) infants after immunization, but none before immunization (P < 0.001). There was no substantial change in recorded apnoea. No serious adverse events were noted. Four (8%) infants underwent a septic work up post-immunization. The C-reactive protein was increased in all four infants, but other tests for sepsis were negative. CONCLUSION: Fever remains a common adverse event following immunization of the preterm infant in spite of the development of a new generation of vaccines.
AIM: Neonatal resuscitation is a common and important intervention. International consensus statements advise how newborns should be resuscitated and suggest equipment to be used. Use of equipment not specifically recommended in these guidelines has been advocated. We wished to determine how widely this supplementary equipment is used in a geographically defined region. METHODS: Each of the 25 tertiary perinatal centres with on-site deliveries in Australia and New Zealand was surveyed. The questionnaire asked about the use of the following items during delivery room resuscitation: pulse oximetry, exhaled carbon dioxide detection, polyethylene wrapping, oxygen blenders, laryngeal mask and oropharyngeal airways. RESULTS: Data were obtained from all centres. Pulse oximetry is used at 12 (48%) centres. Exhaled CO2 detection is used to confirm endotracheal tube placement at three (12%) of the centres. Polyethylene wrapping is used to prevent heat loss in very-low-birthweight infants at delivery at 11 (44%) centres. Oxygen blenders are used to modify the amount of oxygen delivered at nine (36%) centres. Laryngeal mask airways are infrequently used at two (8%) centres. Oropharyngeal airways are infrequently used at five (20%) centres. CONCLUSION: There is considerable variation in the equipment and techniques used to resuscitate newly born infants. Use of equipment not specifically recommended in international consensus statements is widespread. These are potentially effective tools to improve resuscitation. The evidence supporting their use is, however, limited. Urgent evaluation of their efficacy and safety is required before even more widespread use occurs.
OBJECTIVE: In preterm infants, chronic lung disease (CLD) is associated with an increased risk for cerebral palsy (CP). However, systemic postnatal corticosteroid therapy to prevent or treat CLD, although effective in improving lung function, may cause CP. The objective of this study was to determine the effect of systemic postnatal corticosteroid treatment on death and CP and to assess any modification of effect arising from risk for CLD. METHODS: Randomized, controlled trials of postnatal corticosteroid therapy for prevention or treatment of CLD in preterm infants that reported rates of both mortality and CP were reviewed and their data were synthesized. Twenty studies with data on 1721 randomized infants met eligibility criteria. The relationship between the corticosteroid effect on the combined outcome, death or CP, and the risk for CLD in control groups was analyzed by weighted meta-regression. RESULTS: Among all infants who were randomized, a significantly higher rate of CP after corticosteroid treatment (typical risk difference [RD]: 0.05; 95% confidence interval [CI]: 0.02, 0.08) was partly offset by a nonsignificant reduction in mortality (typical RD: -0.02; 95% CI: -0.06 to 0.02). Consequently, there was no significant effect of corticosteroid treatment on the combined rate of mortality or CP (typical RD: 0.03; 95% CI: -0.01 to 0.08). However, on meta-regression, there was a significant negative relationship between the treatment effect on death or CP and the risk for CLD in control groups. With risks for CLD below 35%, corticosteroid treatment significantly increased the chance of death or CP, whereas with risks for CLD exceeding 65%, it reduced this chance. CONCLUSIONS: The effect of postnatal corticosteroids on the combined outcome of death or CP varies with the level of risk for CLD.
We studied the effects of alcohol intake on postexercise muscle glycogen restoration with samples from vastus lateralis being collected immediately after glycogen-depleting cycling and after a set recovery period. Six well-trained cyclists undertook a study of 8-h recovery (2 meals), and another nine cyclists undertook a separate 24-h protocol (4 meals). In each study, subjects completed three trials in crossover order: control (C) diet [meals providing carbohydrate (CHO) of 1.75 g/kg]; alcohol-displacement (A) diet (1.5 g/kg alcohol displacing CHO energy from C) and alcohol + CHO (AC) diet (C + 1.5 g/kg alcohol). Alcohol intake reduced postmeal glycemia especially in A trial and 24-h study, although insulin responses were maintained. Alcohol intake increased serum triglycerides, particularly in the 24-h study and AC trial. Glycogen storage was decreased in A diets compared with C at 8 h (24.4 +/- 7 vs. 44.6 +/- 6 mmol/kg wet wt, means +/- SE, P < 0.05) and 24 h (68 +/- 5 vs. 82 +/- 5 mmol/kg wet wt, P < 0.05). There was a trend to reduced glycogen storage with AC in 8 h (36.2 +/- 8 mmol/kg wet wt, P = 0.1) but no difference in 24 h (85 +/- 9 mmol/kg wet wt). We conclude that 1). the direct effect of alcohol on postexercise glycogen synthesis is unclear, and 2). the main effect of alcohol intake is indirect, by displacing CHO intake from optimal recovery nutrition practices.
Neonatal resuscitation is based on experience with little evidence to support the methods advocated. Current guidelines make no distinction between the techniques for term and very premature infants. The guidelines support the use of 100%, cold, dry oxygen delivered with devices that provide variable peak inspiratory pressures and tidal volumes with no positive end-expiratory pressure (PEEP). It is possible that these techniques damage the lungs. Self-inflating resuscitation bags give no indication about leaks, produce variable inflating pressures, do not provide PEEP and cannot deliver prolonged inflations. Flow-inflating bags will not work if there is leak at the facemask and also have variable inflating pressures. Although they can provide PEEP and deliver prolonged inflations, they require considerable skill to use. The Neopuff is relatively easy to use, provides PEEP and steady inflating pressure and does not achieve the set pressures if there is a mask leak. Continuous positive airway pressure and PEEP are used in the neonatal intensive care unit to maintain lung volume. It is surprising they are not routinely recommended for resuscitation when establishing the lung volume is paramount. Volutrauma is a potential problem in neonatal resuscitation and yet none of the devices give any indication of the tidal volume delivered. There is considerable potential for improvement in techniques of neonatal resuscitation through the application of evidence already available and much scope for further research in this field.
OBJECTIVES: To examine the accuracy of different criteria for the diagnosis of bronchopulmonary dysplasia (BPD), based on the final age at which oxygen therapy was stopped, in predicting pulmonary and neurologic outcomes at 18-month corrected age. STUDY DESIGN: Data were collected prospectively on infants with birth weights between 500 and 999 g enrolled in the Trial of Indomethacin Prophylaxis in Preterms (TIPP) who survived to discharge home. Differing postnatal ages and postmenstrual ages at which supplemental oxygen therapy was no longer required formed the criteria for defining BPD. Diagnostic accuracy of each criterion for defining BPD was calculated for both poor pulmonary and poor neurosensory outcomes. RESULTS: The prevalence of poor pulmonary outcome was 54% and of poor neurosensory outcome was 34% in the 956 infants who were eligible for this analysis. Accuracy of different definitions of BPD was limited but greatest when using supplemental oxygen requirement at 36 weeks' postmenstrual age to predict long-term pulmonary outcome (63%) and 40 weeks to predict long-term neurosensory outcome (68%). CONCLUSIONS: Poor pulmonary outcome and poor neurosensory outcome are common late adverse outcomes in this population. BPD as defined by duration of oxygen therapy is a less accurate surrogate currently than in previous eras.
BACKGROUND: International consensus statements for resuscitation of newborn infants recommend provision of 100% oxygen with positive pressure if assisted ventilation is required. However, 100% oxygen exacerbates reperfusion injury in animals and reduces cerebral perfusion in newborn babies. We aimed to establish whether resuscitation with air decreased mortality or neurological disability in newborn infants compared with 100% oxygen. METHODS: We did a systematic review and meta-analysis of trials that compared resuscitation with air versus 100% oxygen, using the methods of the Cochrane Collaboration. We combined data for similar outcomes in the analysis where appropriate, using a fixed-effects model. FINDINGS: Five trials (two masked and three unmasked), consisting of 1302 newborn infants, fulfilled the inclusion criteria. Most babies were born at or near term in developing countries. In the three unmasked studies, infants resuscitated with room air who remained cyanotic and bradycardic were switched to 100% oxygen at 90 s. The masked studies allowed crossover to the other gas during the first minutes of life. Although no individual trial showed a difference in mortality, the pooled analysis showed a significant benefit for infants resuscitated with air (relative risk 0.71 [95% CI 0.54 to 0.94], risk difference -0.05 [-0.08 to -0.01]). The effect on long-term development could not be reliably determined because of methodological limitations in the one study that followed up infants beyond 12 months of age. INTERPRETATION: For term and near-term infants, we can reasonably conclude that air should be used initially, with oxygen as backup if initial resuscitation fails. The effect of intermediate concentrations of oxygen at resuscitation needs to be investigated. Future trials should include and stratify for premature infants.