Persistent pulmonary hypertension of the newborn: Historical perspectives

For many decades, persistent pulmonary hypertension of the newborn (PPHN) remained a baffling disorder, often confused with cyanotic congenital heart disease, with a very high mortality. Originally described as a condition characterized by clear lung fields and profound hypoxemia, modern diagnostic techniques and novel therapeutics have improved the outcomes of affected newborns. This paper will review the historical aspects of PPHN and enable the reader to see how far we have come but also how far we have to go in conquering this unique disorder.

Hemodynamic management of the micropreemie: When inotropes are not enough

Managing perfusion in the micropreemie is challenging and should be guided by the patho-physiology, gestational and postnatal age of the baby, perinatal history, and the persistence of fetal shunts. The assessment should incorporate bedside tools such as blood pressure, clinical perfusion markers, and functional echocardiography. The multimodal approach to diagnose and identify the cause of hemodynamic compromise paves the way to a targeted approach to treatment. Characterizing the predominant pathophysiologic cause of low cardiac output and impaired cellular metabolism enables a more accurate use of inotropes, vasopressors, and volume support to suit a particular pathophysiologic situation.

The challenging airway: Tracheal agenesis in the newborn

A preterm female presented with severe respiratory distress in the delivery room and was found to have tracheal agenesis with a tracheoesophageal fistula and a congenital heart defect. Tracheal agenesis is uncommon and is often associated with other congenital abnormalities. Although there are surgical options for repair, mortality remains high.

Recurrent late-onset neonatal sepsis traced to breast milk: A case report

Breast milk feeding is an important late-onset sepsis reduction strategy in the Neonatal Intensive Care Unit (NICU). However, multiple studies have reported transfer of bacteria-contaminated breast milk to infants. We describe a case of culture-positive breast milk resulting in persistent Enterococcus bacteremia in an infant. Beyond the development of an infant's innate and specific immunity as well as colonization of the gastrointestinal (GI) tract with commensal organisms, the risk of bacterial translocation from the GI tract into the bloodstream is shaped and modified by maternal health, birth history, and an infant's NICU course. While freezing and/or pasteurizing breast milk reduces or eliminates its bacterial load, it also diminishes its immunologic and nutritional benefits.

New Pharmacologic Approaches to Bronchopulmonary Dysplasia

Bronchopulmonary Dysplasia is the most common long-term respiratory morbidity of preterm infants, with the risk of development proportional to the degree of prematurity. While its pathophysiologic and histologic features have changed over time as neonatal demographics and respiratory therapies have evolved, it is now thought to be characterized by impaired distal lung growth and abnormal pulmonary microvascular development. Though the exact sequence of events leading to the development of BPD has not been fully elucidated and likely varies among patients, it is thought to result from inflammatory and mechanical/oxidative injury from chronic ventilatory support in fragile, premature lungs susceptible to injury from surfactant deficiency, structural abnormalities, inadequate antioxidant defenses, and a chest wall that is more compliant than the lung. In addition, non-pulmonary issues may adversely affect lung development, including systemic infections and insufficient nutrition. Once BPD has developed, its management focuses on providing adequate gas exchange while promoting optimal lung growth. Pharmacologic strategies to ameliorate or prevent BPD continue to be investigated. A variety of agents, to be reviewed henceforth, have been developed or re-purposed to target different points in the pathways that lead to BPD, including anti-inflammatories, diuretics, steroids, pulmonary vasodilators, antioxidants, and a number of molecules involved in the cell signaling cascade thought to be involved in the pathogenesis of BPD.

Assessment of neonatal perfusion

Disorders of perfusion in newborn infants are frequently observed in neonatal intensive care units. The current assessment practices are primarily based on clinical signs. Significant technologic advances have opened new avenues for continuous assessment at the bedside. Combining these devices with functional echocardiography provides an in-depth understanding of perfusion and allows targeting therapy to the pathophysiology rather than monitoring and targeting blood pressure. This change in approach is guided by the fact that perfusion disorders can result from a number of causes and a single management approach might do more harm than good. This approach has the potential to improve long term outcomes but needs to be tested in well-designed trials.

Rescue high frequency ventilation for congenital diaphragmatic hernia

INTRODUCTION

High frequency jet (HFJV) and oscillatory (HFOV) ventilation were used to rescue newborns with congenital diaphragmatic hernia (CDH), who failed conventional mechanical ventilation (CV). Changes in ventilator settings and pulmonary gas exchange were evaluated following transition to high frequency ventilation (HFV).

METHODS

Records of patients with CDH rescued with HFV prior to surgical intervention between 2006 and 2015 were reviewed. Mean airway pressure (Pāw) and arterial blood gases during CV and those obtained within the first hour of HFV were compared. A composite repeated measure analysis was performed to evaluate longitudinal and intergroup variances.

RESULTS

Twenty-seven patients were rescued from CV, 16 by HFJV and 11 by HFOV. The two groups had similar gestational ages and birth weights. Prior to HFV, both groups had similar Pāw, PaCO2, FiO2 and PaO2. HFV was associated with a significant improvement in ventilation, and the rate of decrease of PaCO2 was no different between groups. There was a significantly higher increase in Pāw increase with HFOV compared to HFJV.

CONCLUSIONS

In newborns with CDH rescued with HFV, ventilation improved but Pāw was significantly lower in patients supported with HFJV compared to HFOV.

Systematic Reviews in Neonatal Respiratory Care: Are Some Conclusions Misleading?

An increasing amount of information is currently available in neonatal respiratory care. Systematic reviews are an important tool for clinical decision-making. The challenge is to combine studies that address a specific clinical question and have similar characteristics in terms of populations, interventions, comparators, and outcomes, so that their combined results provide a more precise estimate of the effect that can be validly extrapolated into clinical practice. The concept of heterogeneity is reviewed, emphasizing that it should be considered in a wider perspective and not just as a mere statistical test. A case is made of how well-designed studies of the neonatal respiratory literature, when equivocally combined, can provide very precise but potentially biased results. Systematic reviews in this field and others should be rigorously peer-reviewed before publication to avoid misleading readers to potentially biased conclusions.

Persistent Respiratory Distress in the Term Neonate: Genetic Surfactant Deficiency Diseases

Respiratory distress is one of the most common clinical presentations in newborns requiring admission to a Neonatal Intensive Care Unit (NICU). Many of these infants develop respiratory distress secondary to surfactant deficiency, which causes an interstitial lung disease that can occur in both preterm and term infants. Pulmonary surfactant is a protein and lipid mixture made by type II alveolar cells, which reduces alveolar surface tension and prevents atelectasis. The etiology of surfactant deficiency in preterm infants is pulmonary immaturity and inadequate production. Term infants may develop respiratory insufficiency secondary to inadequate surfactant, either from exposure to factors that delay surfactant synthesis (such as maternal diabetes) or from dysfunctional surfactant arising from a genetic mutation. The genetics of surfactant deficiencies are very complex. Some mutations are lethal in the neonatal period, while others cause a wide range of illness severity from infancy to adulthood. Genes that have been implicated in surfactant deficiency include SFTPA1, SFTPA2, SFTPB, SFTPC, and SFTPD (which encode for surfactant proteins A, B, C, and D, respectively); ABCA3 (crucial for surfactant packaging and secretion); and NKX2 (a transcription factor that regulates the expression of the surfactant proteins in lung tissue). This article discusses the interplay between the genotypes and phenotypes of newborns with surfactant deficiency to assist clinicians in determining which patients warrant a genetic evaluation.

Effect of Sustained Inflations vs Intermittent Positive Pressure Ventilation on Bronchopulmonary Dysplasia or Death Among Extremely Preterm Infants: The SAIL Randomized Clinical Trial

IMPORTANCE

Preterm infants must establish regular respirations at delivery. Sustained inflations may establish lung volume faster than short inflations.

OBJECTIVE

To determine whether a ventilation strategy including sustained inflations, compared with standard intermittent positive pressure ventilation, reduces bronchopulmonary dysplasia (BPD) or death at 36 weeks' postmenstrual age without harm in extremely preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

Unmasked, randomized clinical trial (August 2014 to September 2017, with follow-up to February 15, 2018) conducted in 18 neonatal intensive care units in 9 countries. Preterm infants 23 to 26 weeks' gestational age requiring resuscitation with inadequate respiratory effort or bradycardia were enrolled. Planned enrollment was 600 infants. The trial was stopped after enrolling 426 infants, following a prespecified review of adverse outcomes.

INTERVENTIONS

The experimental intervention was up to 2 sustained inflations at maximal peak pressure of 25 cm H2O for 15 seconds using a T-piece and mask (n = 215); standard resuscitation was intermittent positive pressure ventilation (n = 211).

MAIN OUTCOME AND MEASURES

The primary outcome was the rate of BPD or death at 36 weeks' postmenstrual age. There were 27 prespecified secondary efficacy outcomes and 7 safety outcomes, including death at less than 48 hours.

RESULTS

Among 460 infants randomized (mean [SD] gestational age, 25.30 [0.97] weeks; 50.2% female), 426 infants (92.6%) completed the trial. In the sustained inflation group, 137 infants (63.7%) died or survived with BPD vs 125 infants (59.2%) in the standard resuscitation group (adjusted risk difference [aRD], 4.7% [95% CI, -3.8% to 13.1%]; P = .29). Death at less than 48 hours of age occurred in 16 infants (7.4%) in the sustained inflation group vs 3 infants (1.4%) in the standard resuscitation group (aRD, 5.6% [95% CI, 2.1% to 9.1%]; P = .002). Blinded adjudication detected an imbalance of rates of early death possibly attributable to resuscitation (sustained inflation: 11/16; standard resuscitation: 1/3). Of 27 secondary efficacy outcomes assessed by 36 weeks' postmenstrual age, 26 showed no significant difference between groups.

CONCLUSIONS AND RELEVANCE

Among extremely preterm infants requiring resuscitation at birth, a ventilation strategy involving 2 sustained inflations, compared with standard intermittent positive pressure ventilation, did not reduce the risk of BPD or death at 36 weeks' postmenstrual age. These findings do not support the use of ventilation with sustained inflations among extremely preterm infants, although early termination of the trial limits definitive conclusions.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02139800.

Medico-legal implications of hypothermic neuroprotection in the newborn

Hypoxic-ischemic encephalopathy (HIE) continues to be a significant source of long term neurological sequelae in infants born at or near term. In the past decade, selective head or whole body cooling has shown promising benefit in ameliorating some of the brain injury from intrapartum asphyxial insults and has become standard care in most developed countries. A decision to offer neuroprotective hypothermia (NPH) may engender subsequent litigation because it presupposes an acute intrapartum injury. Conversely, failing to offer cooling may be interpreted as a violation in the standard of care. In this paper, we review the clinical aspects of NPH and the medico-legal scenarios often seen after acute birth injury.

Basics of Infant Conventional Mechanical Ventilation: An Interactive Animated Teaching Module

INTRODUCTION

While conventional mechanical ventilation is a common therapy in the neonatal intensive care unit (NICU), pediatric residents receive insufficient instruction. This stand-alone computer module provides an interactive method of learning basic infant pulmonary physiology and principles of mechanical ventilation.

METHODS

This module runs offline and is compatible with a variety of operating systems. Participants complete a six-question, case-based pretest. The seven-section instructional module is self-paced, narrated, animated, and interactive. Learners can repeat each section as needed. At the conclusion of the module, participants complete the same six-question test and receive feedback. In total, the module requires 15-20 minutes to complete.

RESULTS

The curriculum has been implemented at the beginning of the NICU rotation over a 2-year period within our pediatric residency program. Participants preferred this interactive module and had higher posttest scores when compared to a PowerPoint presentation. After 4 months, there was evidence of knowledge decay.

DISCUSSION

The interactive module is enjoyable, effective, and convenient. It engages participants in active learning and allows them to control the time and pace of their instruction. We have implemented the curriculum within our residency program and believe it would be useful for a variety of NICU health care providers.

Bronchopulmonary dysplasia: Myths of pharmacologic management

Bronchopulmonary dysplasia (BPD) is the leading cause of long-term respiratory morbidity in newborns who require respiratory support at birth. BPD is a multifactorial disorder, and infants are frequently subjected to treatment with multiple pharmacologic agents of dubious efficacy and questionable safety, including diuretics, bronchodilators, corticosteroids, anti-reflux medications, and pulmonary vasodilators. These agents, with narrow therapeutic indices, are widely used despite the lack of an evidence base, and some may do more harm than good. It is incumbent on the clinician to establish a risk:benefit ratio and to avoid drugs that have little efficacy and a high rate of toxicity.

Pulmonary diagnostics

Term infants with respiratory distress may have extremely varied etiologies of their illnesses. These range from anatomical malformations to infectious or inflammatory conditions to genetic, metabolic, or neurological abnormalities. This article reviews the present array of diagnostic studies available to the clinician, including the physical examination, imaging (radiography, computed tomography, magnetic resonance imaging, ultrasound, and nuclear scanning techniques), lung mechanics and function testing, evaluation of gas exchange (blood gases, pulse oximetry, transcutaneous monitoring, and end-tidal carbon monoxide measurements), and anatomical studies (bronchoscopy and lung biopsy). These tests and procedures are reviewed and a stepwise approach recommended.

Congenital chylothorax

Congenital chylothorax (CC) results from multiple lymphatic vessel anomalies or thoracic cavity defects and may accompany other congenital anomalies. Fetal chylothorax may increase the risk of death and complications from pleural space lymphatic fluid accumulation, which compromises lung development, pulmonary, and cardiovascular function and from complications arising from the loss of drained lymphatic contents. Prenatal interventions might improve survival in severe cases of fetal chylothorax. The neonatal treatment strategy is generally supportive with interventions that include thoracostomy drainage and attempts to decrease chyle flow using a stepwise approach that begins with the least invasive means. Evidence-based treatment choices are lacking and are much needed. Most cases of CC resolve with time even without specific lymphatic system studies to identify the exact pathology. Expertise in performing lymphatic studies is not universally available. Data on both efficacy and safety of the various therapeutic options are needed to determine the best approach to the treatment of CC.

Administration of Inhaled Pulmonary Vasodilators to the Mechanically Ventilated Neonatal Patient

Pulmonary hypertension is a life-threatening condition that affects people of all ages that can occur as an idiopathic disorder at birth or as part of a variety of cardiovascular and infectious disorders. It is commonly treated with inhaled pulmonary vasodilators such as nitric oxide and less frequently using formulations and analogs of prostacyclin. To minimize systemic effects and preserve pulmonary vasodilation, vasodilators are often administered directly into the airway. Nitric oxide is the only USA Food and Drug Administration-approved inhaled pulmonary vasodilator that can be used during mechanical ventilation. Over the past two decades, interest has grown in the use of aerosolized prostacyclin and prostacyclin analogs for the treatment of pulmonary hypertension during mechanical ventilation. Clinicians who administer inhaled prostacyclin may not have a clear understanding of its risks because of the lack of data from large clinical trials examining safety and efficacy; moreover, its safe use remains poorly documented. The off-label use of drugs is legitimate, but prescribers must recognize the potential complications and liability in doing so. This manuscript aims to address potential problems related to the aerosol administration of pulmonary vasodilators in the mechanically ventilated neonatal patient.

Continuous Positive Airway Pressure: To Bubble or Not to Bubble?

Continuous positive airway pressure (CPAP) systems can be broadly grouped into continuous flow or variable flow devices. Bubble CPAP (bCPAP) is a continuous flow device and has physiologic properties that could facilitate gas exchange. Its efficacy has been reported to be similar to variable flow CPAP systems when used as a primary mode of respiratory support. Post-extubation bCPAP is reported to significantly reduce extubation failure rates among preterm infants ventilated for less than 2 week when compared to Infant flow driver CPAP (variable flow). bCPAP has been successfully used in resource-poor settings. The success on CPAP is however dependant on good nursing care and clear management protocols for weaning and escalation of care.

Real-time pulmonary graphics

Real-time pulmonary graphics now enable clinicians to view lung mechanics and patient-ventilator interactions on a breath-to-breath basis. Displays of pressure, volume, and flow waveforms, pressure-volume and flow-volume loops, and trend screens enable clinicians to customize ventilator settings based on the underlying pathophysiology and responses of the individual patient. This article reviews the basic concepts of pulmonary graphics and demonstrates how they contribute to our understanding of respiratory physiology and the management of neonatal respiratory failure.

Sildenafil for pulmonary hypertension complicating bronchopulmonary dysplasia

Sildenafil, a phospohodiesterase-5 inhibitor, is widely used to treat pulmonary hypertension in infants with bronchopulmonary dysplasia despite a lack of evidence to support either safety or efficacy and US FDA advice against its use.

Neonatal hypotension: dopamine or dobutamine?

Controversy surrounds the assessment of perfusion and the methods currently utilised to define hypotension, especially blood pressure. There is growing agreement to assess heart function when selecting inotropic therapy and use bedside tools such as echocardiography for assessing at-risk infants. Both dopamine and dobutamine have comparative efficacy, and in certain disease states with immature myocardium there could be potential advantages in using dobutamine. The concomitant use of hydrocortisone has been shown to be beneficial when escalating doses of first-line inotropes are used. Other inotropes require further study through randomised trials for their safety and efficacy to be established.

Surfactant-associated proteins: structure, function and clinical implications

Surfactant replacement therapy is now the standard of care for infants with respiratory distress syndrome. As the understanding of surfactant structure and function has evolved, surfactant-associated proteins are now understood to be essential components of pulmonary surfactant. Their structural and functional diversity detail the complexity of their contributions to normal pulmonary physiology, and deficiency states result in significant pathology. Engineering synthetic surfactant protein constructs has been a major research focus for replacement therapies. This review highlights what is known about surfactant proteins and how this knowledge is pivotal for future advancements in treating respiratory distress syndrome as well as other pulmonary diseases characterized by surfactant deficiency or inactivation.

Lucinactant for the prevention of respiratory distress syndrome in premature infants

Respiratory distress syndrome (RDS) is the leading cause of neonatal morbidity and mortality in premature infants. It is caused by surfactant deficiency and lung immaturity. Lucinactant is a synthetic surfactant containing sinapultide, a bioengineered peptide mimic of surfactant-associated protein B. A meta-analysis of clinical trials demonstrates that lucinactant is as effective as animal-derived surfactants in preventing RDS in premature neonates, and in vitro studies suggest it is more resistant to oxidative and protein-induced inactivation. Its synthetic origin confers lower infection and inflammation risks as well other potential benefits, which may make lucinactant an advantageous alternative to its animal-derived counterparts, which are presently the standard treatment for RDS.

Esophageal and rectal temperatures as estimates of core temperature during therapeutic whole-body hypothermia

We monitored whole-body cooling concurrently by both esophageal and rectal probes. Esophageal temperature was significantly higher compared with simultaneous rectal temperature during cooling, with a temperature gradient ranging from 0.46 to 1.03°C (median, 0.8°C; IQR, 0.6-0.8°C). During rewarming, this temperature difference disappeared.

Distribution and severity of hypoxic-ischaemic lesions on brain MRI following therapeutic cooling: selective head versus whole body cooling

BACKGROUND

Whole body cooling (WBC) cools different parts of the brain uniformly, and selective head cooling (SHC) cools the superficial brain more than the deeper brain structures. In this study, the authors hypothesised that the hypoxic-ischaemic lesions on brain MRI following cooling would differ between modalities of cooling.

AIM

To compare the frequency, distribution and severity of hypoxic-ischaemic lesions on brain MRI between SHC or WBC.

METHODS

In a single centre retrospective study, 83 infants consecutively cooled using either SHC (n=34) or WBC (n=49) underwent brain MRI. MRI images were evaluated by a neuroradiologist, who was masked to clinical parameters and outcomes, using a basal ganglia/watershed (BG/W) scoring system. Higher scores (on a scale of 0 to 4) were given for more extensive injury. The score has been reported to be predictive of neuromotor and cognitive outcome at 12 months.

RESULTS

The two groups were similar for severity of depression as assessed by a history of an intrapartum sentinel event, Apgar scores, initial blood pH and base deficit and early neurological examination. However, abnormal MRI was more frequent in the SHC group (SHC 25 of 34, 74% vs WBC 22 of 49, 45%; p=0.0132, OR 3.4, 95% CI 1.3 to 8.8). Infants from the SHC group also had more severe hypoxic-ischaemic lesions (median BG/W score: SHC 2 vs WBC 0, p=0.0014).

CONCLUSIONS

Hypoxic-ischaemic lesions on brain MRI following therapeutic cooling were more frequent and more severe with SHC compared with WBC.

When bad things happen: adverse event reporting and disclosure as patient safety and risk management tools in the neonatal intensive care unit

The Institute of Medicine has recommended a change in culture from "name and blame" to patient safety. This will require system redesign to identify and address errors, establish performance standards, and set safety expectations. This approach, however, is at odds with the present medical malpractice (tort) system. The current system is outcomes-based, meaning that health care providers and institutions are often sued despite providing appropriate care. Nevertheless, the focus should remain to provide the safest patient care. Effective peer review may be hindered by the present tort system. Reporting of medical errors is a key piece of peer review and education, and both anonymous reporting and confidential reporting of errors have potential disadvantages. Diagnostic and treatment errors continue to be the leading sources of allegations of malpractice in pediatrics, and the neonatal intensive care unit is uniquely vulnerable. Most errors result from systems failures rather than human error. Risk management can be an effective process to identify, evaluate, and address problems that may injure patients, lead to malpractice claims, and result in financial losses. Risk management identifies risk or potential risk, calculates the probability of an adverse event arising from a risk, estimates the impact of the adverse event, and attempts to control the risk. Implementation of a successful risk management program requires a positive attitude, sufficient knowledge base, and a commitment to improvement. Transparency in the disclosure of medical errors and a strategy of prospective risk management in dealing with medical errors may result in a substantial reduction in medical malpractice lawsuits, lower litigation costs, and a more safety-conscious environment.

Does phenobarbital improve the effectiveness of therapeutic hypothermia in infants with hypoxic-ischemic encephalopathy?

OBJECTIVE

To determine whether phenobarbital (PB) given before therapeutic hypothermia to infants with hypoxic-ischemic encephalopathy (HIE) augments the neuroprotective efficacy of hypothermia.

STUDY DESIGN

Records of 68 asphyxiated infants of 36 weeks' gestation, who received hypothermia for moderate or severe HIE were reviewed. Some of these infants received PB prophylactically or for clinical seizures. All surviving infants had later brain magnetic resonance imaging (MRI). The composite primary outcome of neonatal death related to HIE with worsening multiorgan dysfunction despite maximal treatment, and the presence of post-hypothermia brain MRI abnormalities consistent with hypoxic-ischemic brain injury, were compared between the infants who received PB before initiation of hypothermia (PB group, n=36) and the infants who did not receive PB before or during hypothermia (No PB group, n=32). Forward logistic regression analysis determined which of the pre-hypothermia clinical and laboratory variables predict the primary outcome.

RESULT

The two groups were similar for severity of asphyxia as assessed by Apgar scores, initial blood pH and base deficit, early neurologic examination, and presence of an intrapartum sentinel event. The composite primary outcome was more frequent in infants from the PB group (PB 78% versus No PB 44%, P=0.006, odds ratio 4.5, 95% confidence interval 1.6 to 12.8). Multivariate analysis identified only the PB receipt before initiation of hypothermia (P=0.002, odds ratio 9.5, 95% confidence interval 2.3 to 39.5), and placental abruption to be independently associated with a worse primary outcome.

CONCLUSION

PB treatment before cooling did not improve the composite outcome of neonatal death or the presence of an abnormal post-hypothermia brain MRI, but the long-term outcomes have not yet been evaluated.

Myth: mechanical ventilation is a therapeutic relic

Non-invasive respiratory support techniques such as continuous positive airway pressure (CPAP) have been increasingly used for management of surfactant-deficient lung disease in preterm infants. The successful use of this approach depends upon the condition of the baby at birth and requires the establishment of spontaneous breathing at birth. The reported advantages of CPAP in observational studies demonstrating a reduction in chronic lung disease have not been substantiated in recently reported well-designed randomised trials. This approach is now more established in larger and more mature preterm infants, and proper patient selection with close observation should be exercised when used in extremely low gestational age infants.

Clinical course of symptomatic spontaneous pneumothorax in term and late preterm newborns: report from a large cohort

The purpose of this observational study was to characterize the clinical course of newborn infants with spontaneous pneumothorax and to identify those infants who eventually required further interventions. We performed a retrospective review of newborns with symptomatic spontaneous pneumothorax, born between January 2002 and December 2007. Seventy-six infants ≥36 weeks' gestation were identified with symptomatic spontaneous pneumothorax. Twenty-two (29%) of the 76 infants with spontaneous pneumothorax required either thoracentesis or/and thoracostomy drainage, and 54 (71%) were managed without such intervention. In all, 18 (24%) infants received mechanical ventilation and 12 (16%) infants developed persistent pulmonary hypertension (PPHN) during the course of illness. Ten of the 22 infants requiring thoracentesis and/or thoracostomy for progressively worsening respiratory distress developed PPHN. Seven of these 10 infants with PPHN received inhaled nitric oxide, and four infants subsequently required extracorporeal membrane oxygenation. In contrast, the majority of the infants (50 of 54, 93%) not requiring thoracentesis or/and thoracostomy could be managed simply with supplemental oxygen or close observation. Progressively worsening respiratory distress prompting intervention in infants with spontaneous pneumothorax may indicate presence of PPHN that needs prompt recognition and referral to tertiary-level neonatal units for escalating respiratory support.

Multicenter crossover study of automated control of inspired oxygen in ventilated preterm infants

OBJECTIVE

To determine the efficacy and safety of automated adjustment of the fraction of inspired oxygen (Fio(2)) adjustment in maintaining arterial oxygen saturation (Spo(2)) within an intended range for mechanically ventilated preterm infants with frequent episodes of decreased Spo(2).

METHODS

Thirty-two infants (gestational age [median and interquartile range]: 25 weeks [24-27 weeks]; age: 27 days [17-36 days]) were studied during 2 consecutive 24-hour periods, one with Fio(2) adjusted by clinical staff members (manual) and the other by an automated system (automated), in random sequence.

RESULTS

Time with Spo(2) within the intended range (87%-93%) increased significantly during the automated period, compared with the manual period (40% ± 14% vs 32% ± 13% [mean ± SD]). Times with Spo(2) of >93% or >98% were significantly reduced during the automated period (21% ± 20% vs 37% ± 12% and 0.7% vs 5.6% [interquartile ranges: 0.1%-7.2% and 2.7%-11.2%], respectively). Time with Spo(2) of <87% increased significantly during the automated period (32% ± 12% vs 23% ± 9%), with more-frequent episodes with Spo(2) between 80% and 86%, whereas times with Spo(2) of <80% or <75% did not differ between periods. Hourly median Fio(2) values throughout the automated period were lower and there were substantially fewer manual Fio(2) changes (10 ± 9 vs 112 ± 59 changes per 24 hours; P < .001), compared with the manual period.

CONCLUSIONS

In infants with fluctuations in Spo(2), automated Fio(2) adjustment improved maintenance of the intended Spo(2) range led to reduced time with high Spo(2) and more-frequent episodes with Spo(2) between 80% and 86%.

Surfactant replacement therapy in the neonate: beyond respiratory distress syndrome

Surfactant-replacement therapy is a life-saving treatment for preterm infants with respiratory distress syndrome, a disorder characterized by surfactant deficiency. Repletion with exogenous surfactant decreases mortality and thoracic air leaks and is a standard practice in the developed world. In addition to respiratory distress syndrome, other neonatal respiratory disorders are characterized by surfactant deficiency, which may result from decreased synthesis or inactivation. Two of these disorders, meconium aspiration syndrome and bronchopulmonary dysplasia, might also be amenable to surfactant-replacement therapy. This paper discusses the use of surfactant-replacement therapy beyond respiratory distress syndrome and examines the evidence to date.

Mechanical ventilation of the neonate: should we target volume or pressure?

For more than 40 years conventional mechanical ventilation has been used for the treatment of neonatal respiratory failure. Until relatively recently, this was accomplished with time-cycled pressure-limited ventilation, using intermittent mandatory ventilation. Earlier attempts at volume-targeted ventilation were largely ineffective because of technological limitations. The advent of microprocessor-based devices gives the clinician an option to choose either target variable to treat neonatal patients. This paper reviews the principles of each and the accumulated evidence.

Long term follow-up of very low birthweight infants from a neonatal volume versus pressure mechanical ventilation trial

BACKGROUND

A previous randomised trial showed volume controlled ventilation (VCV) was efficacious in ventilating very preterm and extremely low birthweight babies.

OBJECTIVE

To compare long term survival, pulmonary morbidities and gross neurodevelopmental outcomes of babies randomised to either VCV or pressure limited ventilation (PLV) for treatment of respiratory distress syndrome.

DESIGN/METHODS

Masked evaluation of health status, including frequency of respiratory illness, use of medications, hospital admissions, and gross neurodevelopmental status were obtained using a structured parental questionnaire and verification from medical records.

RESULTS

94 of 109 children (86%) survived to discharge. Three died after discharge (2 VCV, 1 PLV). Modality of ventilation did not affect overall mortality; seven VCV children died (12%) versus 11 PLV (21%) (OR 0.5 (95% CI 0.1 to 1.4), p = 0.13). Respiratory abnormalities were present in 32 (37%), and 26 (30%) required hospital readmission. There was no significant difference in readmission rates between the two groups: VC 13/45 (29%) and PLV 19/40 (47%) (OR 0.4 (0.1 to 1.1), p = 0.07). Modality of ventilation did not affect frequency of respiratory illness: VC 12 (27%) and PLV 14 (35%) (OR 0.46 (0.1 to 1.1), p = 0.09). However, significantly fewer VCV children (13%, n = 6) compared to PLV children (32%, n = 13) required treatment with inhaled steroids/bronchodilators (OR 0.3 (0.1 to 0.9), p = 0.04). Nine children had severe neurodevelopmental disability (cerebral palsy, blindness, deafness) (9.8%; 3 VCV, 6 PLV 6) (OR 0.4 (0.09 to 1.7)).

CONCLUSIONS

The efficacy of VCV in very preterm and low birth babies appears to be maintained on longer term evaluation.

Severe intraventricular hemorrhage in preterm infants: comparison of risk factors and short-term neonatal morbidities between grade 3 and grade 4 intraventricular hemorrhage

Grade 3 intraventricular hemorrhage (IVH) (without parenchymal involvement) and grade 4 IVH (with parenchymal involvement) are often combined into description of a single entity, usually "severe" IVH, despite different long-term neurodevelopmental outcome. Although risk factors for severe IVH have already been well described, it is not known if these risk factors and associated short-term neonatal morbidities are different for grade 3 and grade 4 IVH, and indeed, this clustering of grade 3 and grade 4 IVH into severe IVH precludes further delineation of the potential risk and protective factors that can be altered to reduce the incidence of grade 4 IVH, which is presumably associated with worse outcome compared with grade 3 IVH. We sought to characterize and compare commonly cited risk factors and associated short-term neonatal morbidities between grade 3 and grade 4 IVH in very low-birth-weight (VLBW) infants. We performed a retrospective review of VLBW (birth weight < 1500 g) infants with severe IVH born between January 2001 and March 2007. Fifty-nine (10.5%) of 562 infants surviving beyond 3 days of age had severe IVH as recorded on routine cranial sonography during the first 7 to 10 days of life, 28 had grade 3, and 31 had grade 4 IVH. Infants with grade 4 IVH were younger [gestational age (weeks), grade 4 IVH versus grade 3 IVH: 25.5 +/- 1.7 versus 26.7 +/- 1.7, p = 0.02) and weighed less at birth [birth weight (g), grade 4 IVH versus grade 3 IVH: 860 +/- 214 versus 1007 +/- 253, p = 0.03) compared with infants with grade 3 IVH. Other commonly cited clinical factors that alter the risk for severe IVH, including mode of delivery, pregnancy-induced hypertension, premature and/or prolonged rupture of membranes, maternal fever, maternal bleeding, prenatal steroid administration, maternal magnesium sulfate therapy, 1-minute and 5-minute Apgar scores, need for delivery room resuscitation (epinephrine and chest compressions), surfactant therapy, presence of refractory hypotension, evidence of early onset culture-proven sepsis, use of high-frequency ventilation, presence of pneumothorax, and hemodynamically significant patent ductus arteriosus, were similar between infants with grade 3 and grade 4 IVH. Carbon dioxide tensions (minimum PaC (2), maximum PaCO(2), mean PaCO(2), standard deviation of PaCO(2), and coefficient of variation of PaCO (2)) in infants receiving mechanical ventilation during first 3 postnatal days were also not statistically dissimilar. To determine the variables differentiating grade 3 from grade 4 IVH in the study population, logistic regression analysis confirmed only the independent association of gestational age (odds ratio [OR] 0.6, 95% confidence interval [CI] 0.5 to 0.9, P = 0.012) and maternal magnesium sulfate therapy (OR 0.3, 95% CI 0.07 to 0.9, P = 0.04) with the development of grade 4 IVH. Short-term neonatal morbidities were also similar between infants with grade 3 and grade 4 IVH. Among VLBW infants, the risk of a grade 4 versus grade 3 IVH increases with declining gestational age, but does not appear to be related to other commonly cited clinical factors. This information may be useful for prognostication and may improve the quality of parental counseling.

Neonatal ventilators: how do they differ?

Remarkable technological advances over the past two decades have brought dramatic changes to the neonatal intensive care unit. Microprocessor-based mechanical ventilation has replaced time-cycled, pressure-limited, intermittent mandatory ventilation with almost limitless options for the management of respiratory failure in the prematurely born infant. Unfortunately, much of the infusion of technology occurred before the establishment of a convincing evidence base. This review focuses on the basic principles of mechanical ventilation, nomenclature and the characteristics of both conventional and high-frequency devices.

Pulmonary dysfunction and therapeutic hypothermia in asphyxiated newborns: whole body versus selective head cooling

Compared with whole body cooling (WBC), selective head cooling (SHC) of asphyxiated newborns presumably allows effective brain cooling with less systemic hypothermia and potentially fewer systemic adverse effects. It is not known if pulmonary dysfunction, one of the potential adverse systemic effects of therapeutic hypothermic neuroprotection, differs with the method of cooling. We sought to investigate if pulmonary mechanics and gas exchange during therapeutic hypothermia differ between WBC and SHC. The severity of pulmonary dysfunction was determined in 59 asphyxiated newborns receiving therapeutic hypothermic neuroprotection by either SHC ( N = 31) or WBC ( N = 28). Ventilatory parameters and simultaneous alveolar-arterial oxygen gradient (A-a DO (2)) and partial pressure of carbon dioxide, arterial (PaCO (2)) were measured before the start of cooling (baseline), and at 4, 8, 12, 24, 48, and 72 hours of cooling. The diagnosis of persistent pulmonary hypertension of the newborn (PPHN) was established by echocardiography. Clinical monitoring and treatment during cooling, whether SHC or WBC, were similar. All (96%) but two infants (from the SHC group) required mechanical ventilation of varying duration during cooling, and nine infants (15%) developed PPHN. The baseline ventilator pressures requirement, and A-a DO (2) were similar among the 48 ventilated infants without PPHN (WBC 23, SHC 25) at the start of cooling. Ventilatory requirements remained modest and did not differ with the method of cooling. Similar numbers of infants without PPHN were able to be extubated after improvement in respiratory status while being cooled (WBC 42.8% versus SHC 37.9%, P = 0.79, odds ratio [OR] 1.2, 95% confidence interval [CI] 0.4 to 3.5). Nine infants (WBC 5, SHC 4) developed PPHN. Six of the nine (WBC 4, SHC 2) required inhaled nitric oxide therapy, and one infant from the WBC group subsequently required extracorporeal membrane oxygenation. The incidence of PPHN was similar in both the WBC and SHC groups (17.8% versus 12.9%, P = 0.72, OR 1.5, 95% CI 0.3 to 6.1). Pulmonary dysfunction is common but not severe in asphyxiated infants during therapeutic hypothermia. Pulmonary mechanics and gas exchange do not differ with the method of achieving hypothermia.

The effect of two levels of pressure support ventilation on tidal volume delivery and minute ventilation in preterm infants

OBJECTIVE

To study the effect of different levels of pressure support ventilation (PSV) on respiratory parameters in preterm infants during the weaning phase of mechanical ventilation.

DESIGN/METHODS

In this quasi-experimental crossover study, a total of 19 154 breaths were analysed from 10 ventilated infants of <32 weeks' gestation. Breath-to-breath data on minute ventilation, tidal volume, respiratory rate, peak inspiratory pressure and mean airway pressure were collected during three study epochs: synchronised intermittent mandatory ventilation (SIMV) alone, SIMV with partial PSV (PS(min)), and SIMV with full PSV (PS(max)). PS(min) was set to provide an exhaled tidal volume (V(Te)) between 2.5-4 ml/kg and PS(max) 5-8 ml/kg V(Te). Statistical analyses were performed using analysis of variance (ANOVA) for repeated measures.

RESULTS

The addition of full PSV (PS(max)) was associated with a significant increase in total minute ventilation as compared with SIMV alone (392 ml/kg/min vs 270 ml/kg/min, respectively; p<0.05). This difference in minute ventilation was still present when PS(min) was used (332 ml/kg/min as compared with 270 ml/kg/min in SIMV; p<0.05). There was also a concomitant decrease in the respiratory rate with both PS(max) (59 breaths per minute) and PS(min) (65 breaths per minute) compared with SIMV alone (72 breaths per min) (p<0.05).

CONCLUSIONS

Pressure support ventilation increases total minute ventilation and stabilises breathing in proportion to the level of pressure support used. This may be advantageous and provide a useful ventilation strategy for use during weaning stages of mechanical ventilation in preterm infants.

Medical diagnoses commonly associated with pediatric malpractice lawsuits in the United States

In this article we discuss the medical diagnoses underlying the most common lawsuits involving pediatricians in the United States. Where applicable, specific and general risk-management techniques are noted as a means of increasing patient safety and reducing the risk of medical malpractice exposure.

Newer forms of conventional ventilation for preterm newborns

Although life saving, mechanical ventilation can cause complications such as ventilator-induced lung injury and bronchopulmonary dysplasia in very preterm babies. The ventilator-induced lung injury is multi-factorial. There has been an introduction of a number of newer forms of mechanical ventilation, which are aimed to reduce such complications. These are based on sound physiologic principles and clinicians should familiarize themselves with these advances.

Immediate respiratory management of the preterm infant

Infants born prematurely have underdeveloped lungs characterised by both morphological and biochemical abnormalities. Respiratory distress syndrome (RDS) is the leading cause of morbidity and mortality in this population. Both surfactant replacement therapy with mechanical ventilation and continuous positive airway pressure (CPAP) have been shown to be of benefit. However, considerable controversy exists about how best to use these therapies. This paper will review the pathophysiology of RDS and the evidence supporting each of these treatments.

Intractable respiratory failure in a term newborn

Birth depression unresponsive to conventional resuscitative measures merits careful consideration. The case of a term infant with primary respiratory failure at birth despite extensive intervention is presented. Postmortem examination revealed bilateral pulmonary artery thrombi, which underscores the importance of careful exploration of possible pathogenetic mechanisms.