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.

Should amplitude-integrated electroencephalography be used to identify infants suitable for hypothermic neuroprotection?

OBJECTIVE

Amplitude-integrated electroencephalography (aEEG) has been used adjunctively to identify infants suitable for hypothermic neuroprotection following severe intrapartum asphyxia. To determine whether an early aEEG predicts short-term adverse outcome in infants with significant hypoxic-ischemic encephalopathy (HIE) evaluated for hypothermic neuroprotection.

STUDY DESIGN

The aEEG recordings were obtained within 6 h of birth in infants >or=36 weeks' gestational age during evaluation for possible selective head or whole-body cooling. Recordings were subsequently re-evaluated for both background pattern and voltage abnormalities by a certified reader masked to clinical history and brain-oriented interventions. All infants with moderate or severe HIE evaluated for hypothermic neuroprotection also underwent magnetic resonance imaging (MRI) of the brain at a median postnatal age of 7 days. The predictive value using the aEEG for determining short-term dichotomous outcomes, defined as early death related to HIE, or a characteristic pattern of abnormalities consistent with hypoxic-ischemic injury on the MRI brain scans was assessed.

RESULT

Fifty-four infants with moderate or severe HIE were evaluated with aEEG for hypothermic neuroprotection; 34 infants received selective head cooling, 12 infants underwent total body cooling and 8 infants were not cooled. Outcome data, available for 46 of the 54 infants, revealed a poor correlation between the early aEEG and short-term adverse outcomes, with a sensitivity of 54.8% and negative predictive value (NPV) of only 44%.

CONCLUSION

Because of the poor NPV of an early aEEG for a short-term adverse outcome, its use as an 'additional selection criterion' for hypothermic neuroprotection may not be appropriate.

Is refractory hypotension in preterm infants a manifestation of early ductal shunting?

BACKGROUND

Clinicians frequently use hydrocortisone (HC) to treat vasopressor-resistant hypotension even before establishing its cause.

OBJECTIVE

To identify the etiologic factors leading to development of refractory hypotension, and to assess if patent ductus arteriosus (PDA) is associated with refractory hypotension during the first week of life.

STUDY DESIGN

The medical records of 290 consecutively born infants <or=30 weeks' gestational age (GA) were reviewed to identify the escalating need for vasopressors to maintain mean arterial blood pressure (MABP) at or above a level equal to the GA in completed weeks. Refractory hypotension was defined as MABP unresponsive to fluid boluses and high-dose vasopressors (dopamine and dobutamine at doses 20 microg/kg/min each and/or epinephrine) prompting the use of HC.

RESULTS

Eighty-nine (30.7%) of 290 infants had refractory hypotension between postnatal days 2 and 7. Infants with refractory hypotension were more likely to have a lower birth weight and GA (P<0.001), been treated with surfactant (P=0.004) and received indomethacin for a symptomatic PDA (P<0.001). To identify the etiologic factors, a univariate analysis revealed that the use of high-frequency oscillatory ventilation, presence of air leaks, PDA, sepsis, hyperkalemia and intraventricular hemorrhage (IVH) were significantly associated with refractory hypotension. However, multivariate analysis confirmed the independent association of only PDA (odds ratio (OR) 7.6, 95% confidence interval (CI) 3.3-17.7, P=0.000), severe IVH (OR 2.6, 95% CI 1.1-6.4, P=0.03) and GA (OR 0.7, 95% CI 0.6-0.8, P=0.001).

CONCLUSIONS

Evaluation for early ductal shunting and closure of the ductus, if patent, should be attempted before HC is considered in hypotensive infants with escalating needs for vasopressors.

Surfactant for respiratory distress syndrome: are there important clinical differences among preparations?

PURPOSE OF REVIEW

Respiratory distress syndrome is the leading cause of mortality and morbidity among infants born prematurely. The disorder arises from the developmental and biochemical abnormalities associated with preterm delivery. The decreased number of type II alveolar pneumocytes results in absent or reduced surfactant production, which leads to alveolar instability and a tendency to collapse during expiration and increased work of breathing necessitating the institution of supplemental oxygen therapy and positive pressure mechanical ventilation.

RECENT FINDINGS

Exogenous surfactant replacement therapy has been shown to be effective in the treatment of neonatal respiratory distress syndrome and has become a standard of care in neonatal intensive care units. A number of controversies still exist over a number of issues, however, such as the comparative effectiveness of one surfactant preparation over another, timing of administration, dosing volumes and short versus long-term benefits. Furthermore, the emergence of a newer generation of synthetic, peptide-containing surfactants has opened a new era in surfactant therapy which may have implications for future practice and research.

SUMMARY

This paper discusses these developments and analyses the effectiveness of surfactant therapy against respiratory distress syndrome by appraising the evidence produced from published trials and systemic reviews.

Real-time pulmonary graphic monitoring

Real-time pulmonary graphics allow breath-to-breath assessment of pulmonary mechanics and patient-ventilator interaction. It allows the clinician to customize ventilator settings based on pathophysiology and patient response, and may enable detection of complications before they become clinically apparent. Graphics also provide objective information about the efficacy of pharmacologic agents and changes in patient status over time.

Volume-targeted ventilation of newborns

Traditional management of neonatal respiratory failure has been accomplished with mechanical ventilation delivered by time-cycled, pressure-limited techniques. Although easy to use, this modality results in the delivery of tidal volumes that vary according to pulmonary compliance. In contrast, volume-targeted ventilation delivers a selected tidal volume at variable peak inspiratory pressure, resulting in consistent tidal volume delivery, even in the face of changing compliance. This article reviews salient features of volume-targeted ventilation and a review of the evidence base.

Matching ventilatory support strategies to respiratory pathophysiology

Neonates can suffer from various diseases that impact differently on lung function according to the specific pulmonary pathophysiology. As a consequence, the optimal respiratory support will vary according to disorder. Most randomized trials have only included prematurely born infants who have respiratory distress syndrome (RDS) or infants who have severe respiratory failure. Meta-analysis of the results has demonstrated that for the prematurely born infant who has RDS, prophylactic high-frequency oscillatory ventilation only results in a modest reduction in bronchopulmonary dysplasia, and patient-triggered ventilation (assist/control or synchronized intermittent mandatory ventilation) reduces the duration of ventilation if started in the recovery phase. Whether the newer triggered modes are more efficacious remains to be appropriately tested. In term infants who have severe respiratory failure, extracorporeal membrane oxygenation increases survival, but inhaled nitric oxide only reduces the need for extracorporeal membrane oxygenation. Research is required to identify the optimum respiratory strategy for infants who have other respiratory disorders, particularly bronchopulmonary dysplasia.

In support of pressure support

Present generation mechanical ventilators are available with advanced microprocessor-based technology. Greater emphasis is being placed on the patient controlling the ventilator, rather than the physician controlling it. Pressure support ventilation (PSV) is a form of patient-triggered ventilation that supports spontaneous breathing during mechanical ventilation. It is flow-cycled, allowing the patient to determine the inspiratory time and rate. Each spontaneous breath is terminated when inspiratory flow decelerates to a predefined percentage of peak flow. At present, strict comparisons of the usefulness of PSV with other modalities of synchronized ventilation in newborns remain limited. This article reviews the principles and clinical applications of PSV for newborns who have respiratory failure.

Mechanical ventilation of very low birth weight infants: is volume or pressure a better target variable?

OBJECTIVE

To compare the efficacy and safety of volume-controlled (VC) ventilation to time-cycled pressure-limited (TCPL) ventilation in very low birth weight infants with respiratory distress syndrome (RDS).

STUDY DESIGN

Newborns weighing between 600 and 1500 g and with a gestational age of 24 to 31 weeks who had RDS were randomized to receive either VC or TCPL ventilation and treated with a standardized protocol. The 2 modalities were compared by determining the time required to achieve a predetermined success criterion, on the basis of either the alveolar-arterial oxygen gradient <100 mm Hg or the mean airway pressure <8 cm H(2)O. Secondary outcomes included mortality, duration of mechanical ventilation, and complications commonly associated with ventilation.

RESULTS

The mean time to reach the success criterion was 23 hours in the VC group versus 33 hours in the TCPL group (P = .15). This difference was more striking in babies weighing <1000g (21 versus 58 hours; P = .03). Mean duration of ventilation with VC was 255 hours versus 327 hours with TCPL (P = .60). There were 5 deaths in the VC group and 10 deaths in the TCPL group (P = .10). The incidence of other complications was similar.

CONCLUSION

VC ventilation is safe and efficacious in very low birth weight infants and may have advantages when compared with TCPL, especially in smaller infants.

Can neutrophil responses in very low birth weight infants predict the organisms responsible for late-onset bacterial or fungal sepsis?

OBJECTIVE

To examine neutrophil counts and various neutrophil indices in preterm very low birth weight (VLBW) newborn infants (birth weight <1500 g) with culture-proven late-onset sepsis to determine whether the neutrophil responses could predict the responsible infectious agent.

STUDY DESIGN

Neutrophil parameters were examined during episodes of culture-proven sepsis in a cohort of 1026 VLBW infants, born over a 6-year period and admitted to two different neonatal intensive care units. Revised reference ranges of Mouzinho et al. for circulating neutrophil counts in VLBW infants were used to define the abnormal neutrophil indices.

RESULTS

One hundred sixty-two of 1026 (15.8%) VLBW infants had blood culture-proven late-onset infection. Infections included Gram-positive bacteria (113/162, 70%), Gram-negative bacteria (30/162, 18%) and fungi (19/162, 12%). Of the 162 sepsis episodes, only nine (5.5%) were associated with neutropenia (absolute total neutrophil (ATN) <1100/mm3). Six of the 30 (20%) infants with Gram-negative bacterial sepsis were neutropenic compared to 2.6% infants with Gram-positive bacterial sepsis and none with fungal sepsis (odds ratio: 11; 95% confidence interval: 2.6, 47.3). Neutrophil counts and various neutrophil indices were similar in infants with late-onset Gram-positive bacterial and fungal sepsis; but total white blood cells, and ATN count were significantly lower (P = 0.004 and 0.001, respectively) in infants with late-onset Gram-negative bacterial sepsis.

CONCLUSIONS

In VLBW infants, common organisms causing infection have different effects on neutrophil responses. Occurrence of neutropenia during evaluation of sepsis in sick VLBW infants is more common with Gram-negative bacterial infection.

Fetal-to-neonatal maladaptation

Although the majority of newly born babies will establish normal respiratory and circulatory function without help, 1-2% might run into difficulties because of a disturbance in the normal adaptive processes required for a smooth transition from intrauterine to extrauterine life. An understanding of the normal and abnormal perinatal physiology is important to appreciate the practical differences in the approach to caring for such babies, and also for avoiding actions that might be detrimental in the longer term.

Are newborns receiving premedication before elective intubation?

AIMS

To determine the extent and type of premedication used for elective endotracheal intubation in neonatal intensive care units (NICUs).

METHODS

A pretested questionnaire was distributed via e-mail to the program directors of the neonatology divisions with accredited fellowship programs in Neonatal-Perinatal Medicine in the United States.

RESULTS

Of the 100 individuals contacted, 78 (78%) participated in the survey. Only 34 of the 78 respondents (43.6%) always use any premedication for elective intubation. Nineteen respondents (24.4%) reported to have a written policy regarding premedication. Morphine or fentanyl was used most commonly (57.1%), with a combination of opioids and midazolam or other benzodiazepines used less frequently. Fourteen respondents (25%) also use muscle relaxants with sedation for premedication, but only nine respondents combined paralysis with atropine and sedation.

CONCLUSION

Most neonatology fellowship program directors do not report always using premedication for newborns before elective endotracheal intubation despite strong evidence of physiologic and practical benefits. Only a minority of the NICUs has written guidelines for sedation, which may preclude effective auditing of this practice. Educational interventions may be necessary to ensure changes in clinical practice.

Minimising ventilator induced lung injury in preterm infants

Ventilator induced lung injury continues to occur at an unacceptably high rate, which is inversely related to gestational age. Although the "new BPD" may not be entirely avoidable in the extremely premature infant, recognition of risk factors and adoption of an appropriate ventilatory strategy, along with continuous real time monitoring, may help to minimise lung damage. This paper will review the pathogenesis of ventilator induced lung injury and strategies that may mitigate it.

Lucinactant: a novel synthetic surfactant for the treatment of respiratory distress syndrome

Lucinactant (Surfaxin, Discovery Laboratories) is a synthetic surfactant, which contains the novel peptide, sinapultide, a surfactant-associated protein B mimic. Randomised clinical trials suggest that this compound is a safe and effective treatment for respiratory distress syndrome in preterm infants. It is also being actively investigated for other indications, including meconium aspiration syndrome, treatment of bronchopulmonary dysplasia in neonates, acute respiratory distress syndrome and asthma. A novel aerosol formulation administered with nasal continuous positive airway pressure is also under development for treatment of respiratory insufficiency in neonates. Its non-animal origin may make it an attractive alternative to present animal-derived surfactants by eliminating the risks of infection and immunogenicity related to the latter.

Management of neonatal abstinence syndrome in neonatal intensive care units: a national survey

AIMS

To determine the monitoring and treatment of neonatal abstinence syndrome (NAS) in neonatal intensive care units (NICUs) following opiate or polydrug exposure in utero.

METHODS

A pretested questionnaire was distributed via email to the chiefs of the neonatology divisions with accredited Fellowship programs in Neonatal-Perinatal Medicine in the United States.

RESULTS

Of the 102 individuals contacted, 75 participated in the survey. In all, 41 of the respondents (54.5%) have a written policy regarding the management of neonatal NAS. The method of Finnegan is the most commonly used abstinence scoring system (49 of 75, 65%), while only three respondents use the Lipsitz tool. Opioids (tincture of opium, or morphine sulfate solution) are used most commonly for management of both opioid (63% of respondents) and polydrug (52% of respondents) withdrawal, followed by phenobarbital (32 % of respondents) for polydrug withdrawal and methadone (20% of respondents) for opioid withdrawal. In all, 53 respondents (70%) use phenobarbital, and 19 (25%) use intravenous morphine to control opioid withdrawal seizures, while 61 (81%) use phenobarbital in cases of polydrug withdrawal seizures. Only 53 respondents (70%) always use an abstinence scoring system to determine when to start, titrate, or terminate pharmacologic treatment of neonatal NAS.

CONCLUSION

The management of neonatal psychomotor behavior consistent with withdrawal varies widely, with inconsistent policies to determine its presence or treatment. Only about half of NICUs have written guidelines for the management of NAS, which may preclude effective auditing of this practice. Educational interventions may be necessary to ensure changes in clinical practice.

A crossover analysis of mandatory minute ventilation compared to synchronized intermittent mandatory ventilation in neonates

BACKGROUND

Mandatory minute ventilation (MMV) is a novel ventilator mode that combines synchronized intermittent mandatory ventilation (SIMV) breaths with pressure-supported spontaneous breaths to maintain a desired minute volume. The SIMV rate is automatically adjusted to maintain minute ventilation.

OBJECTIVE

To evaluate MMV in a cohort of infants without parenchymal lung disease alternately ventilated by MMV and SIMV.

DESIGN/METHODS

Neonates >33 weeks' gestational age and electively intubated for medical or surgical procedures were enrolled. Exclusionary criteria included: nonintact respiratory drive or active pulmonary disease. Infants were randomized to receive 2 hours of either SIMV or MMV and then crossed over to the other mode for 2 hours. Ventilator parameters and end-tidal CO(2) (etCO(2)) were measured via inline, mainstream monitoring and recorded every minute.

RESULTS

In total, 20 infants were evaluated. No statistically significant differences were found for overall means between etCO(2), minute volumes, peak inspiratory pressure (PIP), or positive end expiratory pressure (PEEP). However, there was a significant difference in the type of ventilator breaths given and in the mean airway pressure. Additionally, there was a statistically significant negative trend in MMV over time compared to SIMV, although this was subtle and could have been due to extreme cases.

CONCLUSIONS

Neonates with an intact respiratory drive can be successfully managed with MMV without an increase in etCO(2). While this mode generates similar PIP and PEEP, the decrease in mechanical breaths and the mean airway pressure generated with MMV may reduce the risk of some of the long-term complications associated with mechanical ventilation.

Selective serotonin reuptake inhibitor (SSRI) use during pregnancy and effects on the fetus and newborn: a meta-analysis

Selective serotonin reuptake inhibitors (SSRIs) are frequently used to treat depression during pregnancy and the postpartum period. These drugs are capable of crossing the placenta and being transferred to the newborn during lactation. This report reviews the available information regarding the effects of SSRIs on the fetus and newborn; including long-term neurodevelopmental outcomes.

Risk management of severe neonatal hyperbilirubinemia to prevent kernicterus

Our approach for risk management of severe neonatal hyperbilirubinemia to prevent kernicterus--one of the most easily preventable causes of neonatal brain damage--includes management of certain high-risk clinical situations, identification of systems failure, and suggestions for implementation strategies to enhance patient safety.

Medical liability, risk management, and the quality of health care

The medical malpractice situation in many countries is reaching epidemic proportions. This paper examines the concepts of medical liability and professional risk management, as well as the relationship they play in determining the quality of healthcare services. The role of documentation and accurate record keeping is also stressed. High-risk clinical situations and medication errors are also addressed.

Immediate changes in lung compliance following natural surfactant administration in premature infants with respiratory distress syndrome: a controlled trial

OBJECTIVE

To compare immediate changes in lung compliance following the administration of two commercially available natural surfactants.

METHOD

We conducted a prospective, randomized study of 40 preterm infants with respiratory distress syndrome requiring surfactant. Infants received either Infasurf or Survanta. The primary outcome measure was the change in compliance assessed by bedside pulmonary monitoring.

RESULTS

There were no significant changes in dynamic lung compliance within or between the two groups 1 hour after surfactant administration. However, infants given Survanta required more doses per patient (4 vs 2, p=0.05) and were more likely to require >2 doses (57 vs 26%, p=0.05). Infants requiring >1 dose of surfactant had a greater change in airway pressure and improved oxygenation just before the second dose when treated with Infasurf.

CONCLUSIONS

We found no significant difference in acute changes in lung compliance. However, treatment with Infasurf seems to be more long lasting than Survanta.

Can mechanical ventilation strategies reduce chronic lung disease?

Chronic lung disease (CLD) continues to be a significant complication in newborn infants undergoing mechanical ventilation for respiratory failure. Although the aetiology of CLD is multifactorial, specific factors related to mechanical ventilation, including barotrauma, volutrauma and atelectrauma, have been implicated as important aetiologic mechanisms. This article discusses the ways in which these factors might be manipulated by various mechanical ventilatory strategies to reduce ventilator-induced lung injury. These include continuous positive airway pressure, permissive hypercapnia, patient-triggered ventilation, volume-targeted ventilation, proportional assist ventilation, high-frequency ventilation and real-time monitoring.

Severe neutrophilia in an infant with persistent pulmonary hypertension of the newborn

We report the case of a term male infant with severe persistent pulmonary hypertension of the newborn, who developed massive neutrophilia of unknown etiology. An extensive evaluation failed to disclose an obvious cause for his neutrophilia. A bone marrow aspirate was performed and was consistent with a leukemoid reaction. This paper reviews the neonatal leukemoid reaction and its significance.

Gentamicin pharmacokinetics in term newborn infants receiving high-frequency oscillatory ventilation or conventional mechanical ventilation: a case-controlled study

OBJECTIVE

To compare the pharmacokinetics of gentamicin in infants receiving high-frequency oscillatory ventilation (HFOV) with infants receiving conventional mechanical ventilation.

DESIGN

A case-controlled study design was used to compare the pharmacokinetics of gentamicin in critically ill infants receiving HFOV and conventional mechanical ventilation. Medical records of all full-term newborn infants (> or =37 weeks gestational age) who received either high-frequency mechanical ventilation or conventional mechanical ventilation between 1991 and 2001 were reviewed and relevant patient demographics, renal function tests and gentamicin administration and plasma concentration data collected. Elimination rate constant, half-life, volume of distribution and clearance for both groups were calculated using standard kinetics equations.

SETTING

A tertiary care children's hospital.

PATIENTS

Newborn infants, > or =37 weeks gestational age, receiving gentamicin and high-frequency mechanical ventilation or conventional mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

In total, 18 patients were included in the conventional mechanical ventilation group and 15 in the HFOV group. The mean gentamicin dose for conventional mechanical ventilation and HFOV groups infants were 2.52+/-0.07 and 2.5+/-0.07 mg/kg/dose, respectively. Initial dosing interval was 12 hours in all of the conventional mechanical ventilation infants and 13 of the 15 HFOV infants. The dosing interval for the remaining two HFOV infants was 18 hours. No patient in either group demonstrated oliguria. Statistical analysis using the Student t-test for unequal variances yielded significant differences between the two groups with regard to elimination rate constant, half-life, volume of distribution and clearance, with a p value of <0.05 for all the observations. The mean of the highest P(aw) received by each patient in the HFOV group (19.2+/-4.05) was considerably higher than in the conventional mechanical ventilation group (13.4+2.23) (p>0.05).

CONCLUSION

Infants receiving HFOV had reduced gentamicin clearance. Full-term infants receiving HFOV should be initiated at gentamicin dosing intervals of 18 hours rather than the traditional 12 hours recommended for this age group.