Suzanne M. Touch

Assessment of neonatal ventilation during high-frequency oscillatory ventilation.

Objective: To determine alterations in high-frequency oscillatory ventilation (HFOV) performance during clinical ventilator management. Design: Clinical investigation. Setting: Two level III intensive care nurseries in Wilmington, Delaware, and Philadelphia, Pennsylvania. Patients: Thirty infants 1.49 ± 1.01 kg with respiratory distress receiving HFOV. Interventions: Due to the demonstrated benchtop load sensitivity of the HFOV (SensorMedics 3100), we hypothesized that measured tidal volume (Vt/kg) and high-frequency minute ventilation (HFMV) would vary inversely with respiratory rate adjustments and that ventilator performance will be affected with endotracheal tube (ETT) suctioning. Both Vt/kg and HFMV were recorded using a novel hot-wire anemometry technique at the time of ETT suctioning or changes in ventilator settings. Measurements and Main Results: During HFOV it was found that Vt/kg = 2.52 ± 0.68 mL/kg and HFMV = 69 ± 45 ([mL/kg]2 × Hz); effective ventilation was observed in the range of HFMV = 29–113 ([mL/kg]2 × Hz). HFMV decreased with an increase in breathing frequency. Although there was a significant increase in the mean Vt/kg after suctioning events, there was no difference in Vt/kg or HFMV after disconnection of the ETT alone. There were significant alterations in HFOV performance as a result of clinical adjustments in respiratory rate and suctioning. In addition, we found that measured Vt during clinically effective HFOV is at least equivalent to expected deadspace. Conclusions: Measurement of tidal volume and HFMV may be clinically important in optimizing HFOV performance both during ETT suctioning and adjustments to breathing frequency.

Matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase expression profiles in tracheal aspirates do not adequately reflect tracheal or lung tissue profiles in neonatal respiratory distress: observations from an animal model.

Objective: Matrix metalloproteinase (MMP)/tissue inhibitor of matrix metalloproteinase (TIMP) expression in tracheal aspirates (TA) is commonly assayed to represent the protein profile in the lung. This study tests the hypothesis that the profile of MMPs 2, 7, and 9 and the profile of TIMPs 1 and 2 will be different in TA, tracheal tissue, and lung tissue in neonatal respiratory distress. Design: Interventional laboratory study. Setting: An academic medical research facility in northeastern United States. Subjects: Oleic acid–injured, spontaneously breathing newborn piglets. Interventions: Ten piglets (3–4 days old, 2.4 ± 0.4 kg) were instrumented, injured by intravenous administration of oleic acid, and supported on continuous positive airway pressure of 2–5 cm H2O, with or without exogenous surfactant, depending on physiologic requirements. Measurement and Main Results: After 6 hrs, TA, trachea, and lung were obtained for MMP/TIMP analysis by substrate zymography/reverse zymography. TA contained less active (p < .01) and more latent (p < .05) MMP-2 than trachea and lung, and the active/latent ratio was less in TA than in both tissues (p < .01). TA and trachea contained more total (p < .05) and active (p < .01) MMP-9 than did the lung; TA contained more active MMP-9 than trachea (p < .01). MMP-7 was greater in all forms relative to total protein (p < .01) from both tissues compared with TA. Trachea contained more latent MMP-7 than lung (p < .01). TIMP-1 was different across protein sources (p < .01) where TA < trachea < lung. The active MMP-2/TIMP-2 ratio was lower in TA than in lung (p < .01); the MMP-9/TIMP-1 ratio had a significant trend (p < .01) where TA > trachea > lung. Conclusions: The MMP/TIMP profiles in TA do not adequately represent the profiles in either trachea or lung. Thus, MMP/TIMP profiles from TA are limited and should be interpreted for trends rather than actual tissue levels.

Physiologic effects of CPAP: application and monitoring.

Although a wide array of respiratory care modalities has been employed to manage neonatal respiratory distress syndrome (RDS), the recent focus has emphasized strategies that correct lung pathophysiology while protecting the lung from further insult. Continuous positive airway pressure (CPAP) has remained a viable option for NICU infants since its introduction in 1971. Current methods of monitoring allow clinicians to troubleshoot and better understand the physiologic and clinical impact of administering CPAP to neonates with RDS. This article highlights the renewed interest in CPAP therapy and current methods of monitoring.

Thermal Stability and Transition Studies With a Hybrid Warming Device for Neonates

OBJECTIVE: The use of both warmer beds and incubators is common in neonatal intensive care units (NICU), and transferring between these two warming devices is a routine and necessary event. This study was designed to evaluate the efficacy of a new hybrid-warming device, the Versalet™, in transitioning a preterm animal from a warmer bed to an incubator mode and back.STUDY DESIGN: Nine premature lambs were randomized, following delivery, to receive thermal support from a conventional warming bed and an incubator (control group), or from the Versalet™ (study group) in the warmer bed and incubator modes. Core and various surface temperatures, as well as physiological parameters were measured first during warming in the radiant warmer bed mode, Versalet™ or Resuscitaire™ and then during transition to the incubator mode, Versalet™ or Isolette™, and then back to the warmer bed mode.RESULTS: The animals remained stable during all the transitions. Despite careful planning, adverse events occurred in the control group during transfers. There were no significant differences in the temperature or physiologic profiles during any of the transitions in either group.CONCLUSION: Compared with the standard warming technique used in NICUs (separate warmer bed and incubator), the Versalet provides similar thermal and cardiovascular stability without adverse events during transition to different modes of warming. The degree to which this device would contribute to ease of management and improved outcomes in humans needs to be evaluated in a clinical trial.

Managing our first breaths: a reflection on the past several decades of neonatal pulmonary therapy.

Lung disease has been a leading cause of significant morbidity and mortality since neonates first drew breath. Over the past few decades, many treatment options have evolved to aid us in our ability to support neonatal breathing. The history of neonatal pulmonary care, both its successes and controversies, can teach us a great deal about the future of this dynamic field. As new developments occur, we constantly modify the therapies we offer to preterm and term infants. Understanding traditional therapeutic options and knowing what may be on the horizon can help caregivers to better match treatment plans with individual infants. This article reviews advances in mechanical ventilation, adjuvant therapies, and respiratory drugs through the past few decades and speculates on future directions in this field.

Intensive Care Management of the Term Neonate: Are There Regional Differences in Outcome?

The objective of this study was to evaluate the patterns of hospitalization of term infants in 3 major metropolitan areas. We hypothesized that regional practice variation occurred in the care of term infants and that these differences would be reflected in the hospitalization patterns of infants. All infants cared for in an Intensive Care Nursery (ICN) after maternal discharge in 1 of 3 major metropolitan areas followed up by the same neonatal management company were compared (n=4,487). Term infants were grouped into 1 of 2 categories based on illness severity: Group 1 (GI) infants-those who required supplemental oxygen or ventilation for 24 hours or more (n=611); and Group 2 (G2) infants-those infants without an oxygen or ventilation requirement (n=1,549). Excluded were infants in the following categories: birth weight <2,500 grams, major congenital anomalies, surgical patients, extracorporeal membrane oxygenation (ECMO) support, or babies who died before discharge. The number of infants in each of these categories was compared as a percentage of the total number of infants cared for in that region. The average length of stay (ALOS) and percentage of patient days attributed to infants in each category were compared across regions using multiple comparison tests (Tukey). The total ALOS was greatest in City A, as was the ALOS for sick term infants. Patient days for sick term infants were lowest in City C, and healthier term infants comprised the lowest percentage of patient days in City A. This difference resulted in the lowest percentage of patient days for all term admissions in City A. These data demonstrated that significant variation existed in the delivery of care to term neonates among major metropolitan regions. Cities that admitted fewer term infants for observation periods (G2) tended to have sicker term neonates with higher acuity hospitalizations (Gi) and longer lengths of stay (LOS). These findings suggested that a conservative admission policy for this population can decrease overall LOS.

The Intensive Care Management of the Term Neonate: Are There Regional Differences in Outcome?

The Intensive Care Management of the Term Neonate: Are There Regional Differences in Outcome?

Inborn Versus Outborn Neonates in Intensive Care: Is This An Important Variable In Determining Length Of Stay? 1351

We set out to understand some of the factors that alter length of stay(LOS) in the intensive care nursery (ICN). We suspected that the requirement of transport of the neonate during their initial hospitalization may be such a factor, independent of either birthweight or associated diagnosis.

Do Regional Differences in Neonatal Critical Care Effect Length of Stay? 548

The practice patterns in neonatology are often a reflection of training programs, and care may be regionalized. Different styles of neonatal care may result in different outcomes and length of stay (LOS). We hypothesized that regional differences in neonatal practice exist, and that these differences result in variations in LOS.

The Effect of a Practice Guideline on Day of Neonatal Discharge 1157

One of the goals of practice guideline is to unify the timing of nursery discharge. We speculated that an effectively instituted guideline would reduce variability in length of stay (LOS). A guideline for the management of term neonates with sepsis ruled-out was instituted by a disease management system(DM) in three major metropolitan areas.