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.