A randomized comparison of surfactant dosing via a dual-lumen endotracheal tube in respiratory distress syndrome. The Spanish Surfactant Collaborative Group

The Effect of Continuous PEEP Administration during Surfactant Instillation on Cerebral Hemodynamics in Intubated Preterm Infants: A NIRS Study

OBJECTIVE

There is an ongoing debate about the best and comfortable way to administer surfactant. We hypothesized that uninterrupted respiratory support and continuous PEEP implementation while instilling surfactant via endotracheal tube (ETT) with side port will result in higher regional cerebral tissue oxygenation (rcSO2) and the alterations in cerebral hemodynamics will be minimal.

STUDY DESIGN

Preterm infants who required intubation in the delivery room and/or in the first 24 hours of life with gestational age <32 were enrolled. Patients were intubated either via conventional ETT or ETT with side port (Vygon) with appropriate sizes. Following neonatal intensive care unit admission a near-infrared spectroscopy (NIRS) probe was placed on the forehead and each infant was started to be monitored with NIRS. In conventional ETT group, patients separated from the ventilator while surfactant was instilled. In ETT with side port group, respiratory support was not interrupted during instillation. Heart rate, oxygen saturation, rcSO2, cerebral fractional tissue oxygen extraction (cFTOE), and blood pressures were recorded.

RESULTS

A total of 46 infants were analyzed. Surfactant was instilled with conventional ETT in 23 and ETT with side port in 23 infants. Birth weights (1,037 ± 238 vs. 1,152 ± 277 g) and gestational ages (28 ± 2.3 vs. 29 ± 1.6 weeks) did not differ between groups. During instillation of surfactant, rcSO2 levels [61.5 (49-90) vs. 70 (48-85)] and cFTOE levels 0.28 (0.10-0.44) vs. 0.23 (0.03-0.44)] were similar (p = 0.58 and 0.82, respectively).

CONCLUSION

Interruption of respiratory support during surfactant instillation did not significantly alter the cerebral tissue oxygenation. These results did not support our hypothesis and should be confirmed with further studies.

KEY POINTS

· Monitoring intracerebral oxygenation changes during surfactant administration with NIRS is feasible.. · The surfactant administration method does not significantly alter the cerebral oxygenation.. · Surfactant administration itself rather than the method caused a transient drop in cerebral NIRS readings..

Safety and efficacy of a novel double-lumen tracheal tube in neonates with RDS: A prospective cohort study

BACKGROUND

The purpose of this study was to assess the safety and efficacy of a new double-lumen tracheal tube for neonates, with a conventional tracheal tube as a control.

METHOD

Newborns with respiratory distress syndrome (RDS) requiring endotracheal intubation admitted to the tertiary neonatal intensive care unit (NICU) of Qujing Maternal and Child Healthcare Hospital in Yunnan Province between March 2021 and May 2022 were enrolled in this prospective cohort study. Outcome indicators related to effectiveness included mainly the number of intubations, duration of ventilation, duration of oxygenation, and length of stay; safety indicators included any clinical adverse effects during and after intubation. Appropriate stratified and subgroup analyses were performed according to the purpose of intubation, gestational age, and whether the drug was administered via endotracheal tube.

RESULT

A total of 101 neonates were included and divided into two groups based on the choice of tracheal tube: the conventional (n = 50) and new (n = 51) tracheal tube groups. There was no statistical difference between the two groups in terms of adverse effects during and after intubation (p > 0.05). In neonates who were mechanically ventilated without endotracheal surfactant therapy or newborns receiving InSurE technique followed by non-invasive ventilation, no significant differences were found between the two groups regarding any of the efficacy indicators (p > 0.05). However, for neonates on invasive mechanical ventilation, the new tracheal tube allowed for a significant reduction in the duration of mechanical ventilation (96.50[74.00, 144.00] vs. 121.00[96.00, 196.50] hours, p = 0.037) and total ventilation (205.71 ± 80.24 vs. 277.56 ± 117.84 h, p = 0.027), when used as a route for endotracheal drug delivery. Further analysis was performed according to gestational age for newborns requiring intratracheal surfactant administration during mechanical ventilation, and the data showed that for preterm infants, the new tracheal tube not only shortened the duration of mechanical ventilation (101.75 ± 39.72 vs. 155.50 ± 51.49 h, p = 0.026) and total ventilation (216.00 ± 81.60 vs. 351.50 ± 113.79 h, p = 0.010), but also demonstrated significant advantages in reducing the duration of oxygen therapy (9.75 ± 6.02 vs. 17.33 ± 8.43 days, p = 0.042); however, there was no statistical difference in efficacy outcomes between the two groups in full-term infants (p > 0.05).

CONCLUSION

The efficacy and safety of this new tracheal tube are promising in neonates with RDS, especially those requiring surfactant administration via a tracheal tube during mechanical ventilation. Given the limitations of this study, however, the clinical feasibility of this catheter needs to be further confirmed in prospective randomized trials with larger sample sizes.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/showproj.aspx?proj=122073.

Surfactant

Exogenous pulmonary surfactant, widely used in neonatal care, is one of the best-studied treatments in neonatology, and its introduction in the 1990s led to a significant improvement in neonatal outcomes in preterm infants, including a decrease in mortality. This chapter provides an overview of surfactant composition and function in health and disease and summarizes the evidence for its clinical use.

The use of surfactant in the neonatal period- the known aspects, those still under research and those which need to be investigated further

Respiratory distress syndrome is pulmoner insufficiency caused by the lack of surfactant and the main reason of morbidity and mortality in preterm infants. Mothers at high risk of preterm birth should be transferred to perinatal centers with experience for respiratory distress syndrome and ante-natal steroids should be given before 35 weeks' of gestational age. Surfactant treatment should be applied to babies with or at high risk for respiratory distress syndrome. Prophylaxis should be given to infants of <26 weeks of gestational age and to infants requiring entubation in the delivery room. Nasal continuous positive airway pressure should be considered in infants with complete steroid treatment and without entubation need. Early surfactant may be given if entubation is performed during follow-up. Natural forms of surfactant should be preferred when needed. If the infant is stable, early extubation and non-invasive respiratory support should be considered. In this review, the recent studies' current data about surfactant treatment will be discussed.

Delivery and performance of surfactant replacement therapies to treat pulmonary disorders

Lung surfactant is crucial for optimal pulmonary function throughout life. An absence or deficiency of surfactant can affect the surfactant pool leading to respiratory distress. Even if the coupling between surfactant dysfunction and the underlying disease is not always well understood, using exogenous surfactants as replacement is usually a standard therapeutic option in respiratory distress. Exogenous surfactants have been extensively studied in animal models and clinical trials. The present article provides an update on the evolution of surfactant therapy, types of surfactant treatment, and development of newer-generation surfactants. The differences in the performance between various surfactants are highlighted and advanced research that has been conducted so far in developing the optimal delivery of surfactant is discussed.

Surfactants: past, present and future

In 1929 Kurt von Neergaard performed experiments suggesting the presence of pulmonary surfactant and its relevance to the newborn's first breath. Almost 25 years later, Richard Pattle, John Clements and Chris Macklin, each working on the effects of nerve gases on the lungs, contributed to the understanding of the physiology of pulmonary surfactant. About 5 years later Mary Ellen Avery and Jere Mead published convincing evidence that preterm neonates dying of hyaline membrane disease (respiratory distress syndrome, RDS) had a deficiency of pulmonary surfactant. The first trials of nebulized synthetic (protein-free) surfactant to prevent RDS were published soon after Patrick Bouvier Kennedy (son of President John F Kennedy) died of this disorder after treatment in Boston. These trials were unsuccessful; however, Goran Enhorning and Bengt Robertson in the early 1970s demonstrated that natural surfactants (containing proteins) were effective in an immature rabbit model of RDS. Soon after this Forrest Adams showed that a natural surfactant was also effective in an immature lamb model. Working with him was Tetsuro Fujiwara who 2 years later, after returning to Japan, published the seminal article reporting the responses of 10 preterm infants with RDS to a bolus of modified bovine surfactant. During the 1980s there were numerous randomized controlled trials of many different natural and synthetic surfactants, demonstrating reductions in pulmonary air leaks and neonatal mortality. Subsequently natural surfactants were shown to be superior to the protein-free synthetic products. Recently there have been a number of randomized trials comparing different natural surfactant preparations. Commercially available bovine surfactants may have similar efficacy but there is some evidence that a porcine surfactant used to treat RDS with an initial dose of 200 mg per kg is more effective than a bovine surfactant used in an initial dose of 100 mg per kg. Bovine and porcine surfactants have not been compared in trials of prophylaxis. Very recently a new synthetic surfactant with a surfactant protein mimic has been compared with other commercially available natural and synthetic surfactants in two trials. The new surfactant may be superior to one of the older protein-free synthetic surfactants but there is no evidence of its superiority over established natural products and it is currently not approved for clinical use. A number of other new synthetic surfactants have been tested in animal models or in treatment of adults with ARDS, but so far there have been no reports of treatment of neonatal RDS. Natural surfactants work best if given by a rapid bolus into the lungs but less invasive methods such as a laryngeal mask, pharyngeal deposition or rapid extubation to CPAP have showed promise. Unfortunately, delivery of surfactant by nebulization has so far been ineffective. Surfactant treatment has been tried in a number of other neonatal respiratory disorders but only infants with meconium aspiration seem to benefit although larger and more frequent doses are probably needed to demonstrate improved lung function. A surfactant protocol based upon early treatment and CPAP is suggested for very preterm infants. Earlier treatment may improve survival rates for these infants; however, there is a risk of increasing the prevalence of milder forms of chronic lung disease. Nevertheless, surfactant therapy has been a major contribution to care of the preterm newborn during the past 25 years.

[Prenatal corticosteroid and early surfactant therapy in infants born at < or = 30 weeks gestation]

BACKGROUND

Prenatal corticosteroid (PNC) exposure and postnatal surfactant therapy improve outcome in very low birth weight infants (VLBWI). However, the efficacy of PNC in the prevention of chronic lung disease is debated.

OBJECTIVE

To study the effects of PNC exposure on outcome in VLBWI born at < or = 30 weeks' gestation.

PATIENTS AND METHODS

We performed a multicenter, longitudinal study. The Spanish Surfactant Group database (n 5 1,275) was searched and 211 VLBWI born at < or = 30 weeks who received early surfactant therapy (< or = 30 min) were identified. Perinatal events, neonatal management and rates of mortality and complications were evaluated. Data on the subgroup of infants who received PNC (157, 74.4 %) were compared with data on 54 infants who did not receive this therapy.

RESULTS

Mean (+/- SD) birth weight and gestational age were 944 (226) g and 27 (1.8) weeks. Surfactant was given at 16 +/- 13 min (61 % < or = 15 min). A total of 124 infants (58.8 %) developed respiratory distress syndrome. No differences were found in birth weight, gestational age, or Apgar score at 1 and 5 min. However the age at first surfactant dose was lower in infants exposed to PNC. PNC-exposed infants required fewer doses of surfactant, were extubated earlier (58.9 vs. 161 h) and needed a lower FiO2 at 48 h (0.28 vs. 0.35). Moreover, neonatal mortality (15.9 vs. 27.8 %), the incidence of intraventricular hemorrhage (25.2 vs. 50 %), ductus arteriosus (40.3 vs. 63.5 %) and necrotizing enterocolitis (9 vs. 19.2 %) were lower in infants receiving PNC. However, the incidence of chronic lung disease was similar in both groups.

CONCLUSIONS

PNC exposure of VLBWI born at < or = 30 weeks receiving early surfactant therapy reduced mortality and the incidence of certain complications but did not decrease the incidence of chronic lung disease.

Surfactant administration acutely affects cerebral and systemic hemodynamics and gas exchange in very-low-birth-weight infants

OBJECTIVES

To determine whether surfactant administration affects cerebral and systemic hemodynamics and gas exchange in very low birth weight infants and to determine the predominant factor influencing changes in mean cerebral blood flow velocity (mCBFv) after surfactant instillation.

STUDY DESIGN

Fourteen very low birth weight infants with respiratory distress syndrome had continuous monitoring of mCBFv, Paco(2), mean arterial blood pressure (MABP), and Pao(2) before, during, and after the second dose of surfactant. Peak values and relative changes of the 4 variables for 45 minutes after surfactant were calculated. Logistic regression was used to determine the predominant factor influencing changes in mCBFv after surfactant.

RESULTS

Birth weight was 832 +/- 162 grams and gestational age was 25.7 +/- 1.5 weeks. The time from birth to monitoring was 6.9 +/- 1.0 hours. Mean CBFv increased 75.7% +/- 51.6% after surfactant and peaked at 14.4 +/- 5.9 minutes. Paco(2) was highly associated (OR=107.3, P <.0001) with mCBFv; as Paco(2) increased, mCBFv increased. In contrast, MABP (OR=6.7, P=.047) had less impact on mCBFv. Pao(2) was not associated with mCBFv.

CONCLUSIONS

The increases in mCBFv after surfactant administration were predominantly due to increases in Paco(2) and not changes in MABP.

Surfactant therapy for respiratory distress syndrome in premature neonates: a comparative review

Exogenous surfactant therapy has been part of the routine care of preterm neonates with respiratory distress syndrome (RDS) since the beginning of the 1990s. Discoveries that led to its development as a therapeutic agent span the whole of the 20th century but it was not until 1980 that the first successful use of exogenous surfactant therapy in a human population was reported. Since then, randomized controlled studies demonstrated that surfactant therapy was not only well tolerated but that it significantly reduced both neonatal mortality and pulmonary air leaks; importantly, those surviving neonates were not at greater risk of subsequent neurological impairment. Surfactants may be of animal or synthetic origin. Both types of surfactants have been extensively studied in animal models and in clinical trials to determine the optimum timing, dose size and frequency, route and method of administration. The advantages of one type of surfactant over another are discussed in relation to biophysical properties, animal studies and results of randomized trials in neonatal populations. Animal-derived exogenous surfactants are the treatment of choice at the present time with relatively few adverse effects related largely to changes in oxygenation and heart rate during surfactant administration. The optimum dose of surfactant is usually 100 mg/kg. The use of surfactant with high frequency oscillation and continuous positive pressure modes of respiratory support presents different problems compared with its use with conventional ventilation. The different components of surfactant have important functions that influence its effectiveness both in the primary function of the reduction of surface tension and also in secondary, but nonetheless just as important, role of lung defense. With greater understanding of the individual surfactant components, particularly the surfactant-associated proteins, development of newer synthetic surfactants has been made possible. Despite being an effective therapy for RDS, surfactant has failed to have a significant impact on the incidence of chronic lung disease in survivors. Paradoxically the cost of care has increased as surviving neonates are more immature and consume a greater proportion of neonatal intensive care resources. Despite this, surfactant is considered a cost-effective therapy for RDS compared with other therapeutic interventions in premature infants.

Current surfactant use in premature infants

Exogenous surfactant therapy has been a significant advance in the management of preterm infants with RDS. It has become established as a standard part of the management of such infants. Both natural and synthetic surfactants lead to clinical improvement and decreased mortality, with natural surfactants having additional advantages over currently available synthetic surfactants. The use of prophylactic surfactant administered after initial stabilization at birth to infants at risk for RDS has benefits compared with rescue surfactant given to treat infants with established RDS. In infants who do not receive prophylaxis, earlier treatment (before 2 hours) has benefits over later treatment. The use of multiple doses of surfactant is a superior strategy to the use of a single dose, whereas the use of a higher threshold for retreatment seems to be as effective as a low threshold. Adverse effects of surfactant therapy are infrequent and usually not serious. Long-term follow-up of infants treated with surfactant in the neonatal period is reassuring. In the future we are likely to see the development of new types of surfactants. Further research is required to determine the optimal use of surfactant in conjunction with other respiratory interventions.