Mechanical ventilation in special populations

Optimal respiratory support can only be achieved if the ventilator strategy utilized for each individual patient at any given point in the evolution of their disease process is tailored to the underlying pathophysiology. The critically ill newborn infant requires individualized patient care when it comes to mechanical ventilation. This can only occur if the clinician has a good understanding of the different pathophysiologies of a variety of conditions that can lead to respiratory failure. In this chapter we describe the key pathophysiological features of bronchopulmonary dysplasia, meconium aspiration syndrome and lung hypoplasia syndromes with emphasis on congenital diaphragmatic hernia. We review available evidence to guide management an provide specific recommendations for pathophysiologically-based mechanical ventilation support.

Neonatal high frequency ventilation: Current trends and future directions

High frequency ventilation (HFV) in neonates has been in use for over forty years. Some early HFV ventilators are no longer available, but high frequency oscillatory ventilation (HFOV) and jet ventilators (HFJV) continue to be commonly employed. Advanced HFOV models available outside of the United States are much quieter and easier to use, and are available as options on many conventional ventilators, providing important improvements such as tidal volume measurement and targeting. HFJV excels in treating air leak and non-homogenous lung disease and is often used for other diseases as well. High frequency non-invasive ventilation (hfNIV) is a novel application of HFV that remains under investigation. Similar to bubble CPAP, hfNIV has been applied with a variety of high-frequency ventilators. Efficacy and safety of hfNIV with any device have not yet been established. This article describes the current approaches to these HFV therapies and stresses the importance of understanding how each device works and what disease processes may respond best to the technology employed.

Konjenital Diyafragma Hernisi Tanılı Hastalar: 10 Yıllık Tek Merkez Deneyimi

Amaç: Konjenital diyafragma hernisi (KDH), diyafragmanın gelişimsel kusuru olup nadir görülmektedir. Batın içi organların göğüs boşluğuna fıtıklaşmaıs sonucu gelişen akciğer hipoplazisinin şiddeti hastaların prognozunda temel etkendir. Biz bu çalışmamızda, son 10 yıllık süreçte KDH vakalarımızla ilgili deneyimimizi ve mortalite ile ilgili faktörleri değerlendirmeyi amaçladık. Gereç ve Yöntem: Ocak 2012-Aralık 2021 tarihleri arasında KDH tanısı ile yatırılan hastaları retrospektif olarak inceledik. Hastaların demografik özellikleri ile klinik izlem bilgilerini değerlendirip, mortalite üzerinde etkili olan faktörleri inceledik. Bulgular: Toplam 37 KDH’li hastamızdan, 22’sinin exitus olduğun tespit ettik. 19 hastamız başka merkezlerde doğup, tarafımıza sevk edilmişti. Ayrıca 19 hastamızın prenatal tanısı yoktu. Hastalardan 12’si opere edilmeden ilk saatlerde exitus oldu. Exitus olan grupta ek anomali oranı [n=13 (%59.1), n=1 (%6.7) sırasıyla (p=0.002)] istatiksel olarak daha fazlaydı. Opere edilen 25 hastamızdan 15’i taburcu edildi. Opere edilenlerden exitus olan grupta, pulmoner hipertansiyon gelişen hasta sayısı [n=9 (%90), n=4 (%26.7) sırasıyla (p=0.005)] istatiksel olarak daha fazlaydı. Sonuç: Pulmoner hipertansiyon ve ek anomali KDH hastalarında mortalite ile ilişkilidir. Bu hastaların doğumlarının uygun merkezde olması ve deneyimli ekiplerce takip ve tedavilerinin yapılması da önemlidir.

Operative repair in congenital diaphragmatic hernia: How long do we really need to wait?

OBJECTIVE

To analyze preoperative cardiopulmonary support and define preoperative stability relative to timing of surgical repair for CDH neonates not on ECMO.

STUDY DESIGN

We retrospectively analyzed repeated measures of oxygenation index (OI; Paw*FiO₂×100/PaO₂) among 158 neonates for temporal preoperative trends. We defined physiologic stability using OI and characterized ventilator days and discharge age relative to delay in repair beyond physiologic stability.

RESULTS

The OI in the first 24 h of life was temporally reliable and representative of the preoperative mean (ICC 0.70, 95% CI 0.61-0.77). A pre-operative OI of ≤ 9.4 (AUC 0.95) was predictive of survival. Surgical delay after an OI ≤ 9.4 resulted in increased ventilator days (1.4, 95% CI 1.1-1.9) and discharge age (1.5, 95% CI 1.2-2.0). When prospectively applied to a subsequent cohort, an OI ≤ 9.4 was again reflective of physiologic stability prior to repair.

CONCLUSION

OI values are temporally reliable and change minimally after 24 h age. Delay in surgical repair of CDH beyond initial stability increases ventilator days and discharge age without a survival benefit.

LEVEL OF EVIDENCE

Prognosis study, Level III.

Congenital diaphragmatic hernia: a narrative review of controversies in neonatal management

The consequences of most hernias can be immediately corrected by surgical repair. However, this isn't always the case for children born with a congenital diaphragmatic hernia. The derangements in physiology encountered immediately after birth result from pulmonary hypoplasia and hypertension caused by herniation of abdominal contents into the chest early in lung development. This degree of physiologic compromise can vary from mild to severe. Postnatal management of these children remains controversial. Although heavily studied, multi-institutional randomized controlled trials are lacking to help determine what constitutes best practice. Additionally, the results of the many studies currently within the literature that have investigated differing aspect of care (i.e., inhaled nitric oxide, ventilator type, timing of repair, role of extracorporeal membrane oxygenation, etc.) are difficult to interpret due to the small numbers investigated, the varying degree of physiologic compromise, and the contrasting care that exists between institutions. The aim of this paper is to review areas of controversy in the care of these complex kids, mainly: the use of fraction of inspired oxygen, surfactant therapy, gentle ventilation, mode of ventilation, medical management of pulmonary hypertension (inhaled nitric oxide, sildenafil, milrinone, bosentan, prostaglandins), the utilization of extracorporeal membrane oxygenation, and the timing of surgical repair.

Congenital diaphragmatic hernia presenting with symptoms within the first day of life; outcomes from a non-ECMO centre in Denmark

Background

Between 1998 and 2015, we report on the survival of congenital diaphragmatic hernia (CDH)-infants presenting with symptoms within the first 24 h of life, treated at Odense University Hospital (OUH), a tertiary referral non-extracorporeal membrane oxygenation (ECMO) hospital for paediatric surgery.

Methods

We performed a retrospective cohort study of prospectively identified CDH-infants at our centre. Data from medical records and critical information systems were obtained. Baseline data included mode of delivery and infant condition. Outcome data included 24-h, 28-day, and 1 year mortality rates and management data included intensive care treatment, length of stay in the intensive care unit, time of discharge from hospital, and surgical intervention. Descriptive analyses were performed for all variables. Survivors and non-survivors were compared for baseline and treatment data.

Results

Ninety-five infants were identified (44% female). Of these, 77% were left-sided hernias, 52% were diagnosed prenatally, and 6.4% had concurrent malformations. The 28-day mortality rate was 21.1%, and the 1 year mortality rate was 22.1%. Of the 21 non-survivors, nine died within the first 24 h, and 10 were sufficiently stabilised to undergo surgery. A statistically significant difference was observed between survivors and non-survivors regarding APGAR score at 1 and 5 min., prenatal diagnosis, body length at birth, and delivery at OUH.

Conclusions

Our outcome results were comparable to published data from other centres, including centres using ECMO.

Cardiac Function Assessments in Left Bochdalek's Hernia: Clinical Relevance

The objectives of this study were to characterize peri-operative echocardiographic (ECHO) assessments of right ventricular (RV) function and pulmonary hypertension (PH) and ascertain correlation with clinical outcomes in infants with left Bochdalek's hernia (LBH). This retrospective study in a quaternary neonatal intensive care unit involved electronic database search for infants with LBH during January 2009 to July 2017. Demographics, outcomes, and ECHO parameters were accessed from archived databases. Thirty-one infants with mean gestational age and birthweight (BW) 38.4 ± 1.4 weeks and 3079 ± 450 g were included. Postnatal age at surgery was 4.3 ± 2 days. Two infants died before surgery (none after surgery). The survival rate in this cohort of late preterm and term infants with LBH not accompanied by congenital heart disease was 29/31 (93.5%). PH was noted in 28 (90%). Significant changes in biventricular function and pulmonary vascular haemodynamics were noted when reassessed after surgery [RV area change (%), 28 ± 3 vs. 34 ± 4, p = 0.007 and pulmonary artery capacitance (PAC) (ml³ × mmHg^-1), 0.05 ± 0.03 vs. 0.09 ± 0.05, p = 0.02]. The median duration of all respiratory support in those who were operated was 14.7 days (8.5, 25). Significant correlations were noted between pre-operative ECHO assessments and the duration of respiratory support (tricuspid regurgitation, r = 0.63, p = 0.0001 and PAC, r = - 0.52, p = 0.004). Peri-operative functional ECHO provided information about the evolution of cardiac function in infants with LBH.

Prematurity and fetal lung response after tracheal occlusion in fetuses with severe congenital diaphragmatic hernia

OBJECTIVE

To evaluate the independent association of fetal pulmonary response and prematurity to postnatal outcomes after fetal tracheal occlusion for congenital diaphragmatic hernia.

METHODS

Fetal pulmonary response, prematurity (<37 weeks at delivery) and extreme prematurity (<32 weeks at delivery) were evaluated and compared between survivors and non-survivors at 6 months of life. Multivariable analysis was conducted with generalized linear mixed models for variables significantly associated with survival in univariate analysis.

RESULTS

Eighty-four infants were included, of whom 40 survived (47.6%) and 44 died (52.4%). Univariate analysis demonstrated that survival was associated with greater lung response (p=0.006), and the absence of extreme preterm delivery (p=0.044). In multivariable analysis, greater pulmonary response after FETO was an independent predictor of survival (aOR 1.87, 95% CI 1.08-3.33, p=0.023), whereas the presence of extreme prematurity was not statistically associated with mortality after controlling for fetal pulmonary response (aOR 0.52, 95% CI 0.12-2.30, p=0.367).

CONCLUSION

Fetal pulmonary response after FETO is the most important factor associated with survival, independently from the gestational age at delivery.

A simplified formula using early blood gas analysis can predict survival outcomes and the requirements for extracorporeal membrane oxygenation in congenital diaphragmatic hernia

The aims of this study were to investigate whether early arterial blood gas analysis (ABGA) could define the severity of disease in infants with congenital diaphragmatic hernia (CDH). We conducted a retrospective study over a 21-yr period of infants diagnosed with CDH. Outcomes were defined as death before discharge, and extracorporeal membrane oxygenation requirements (ECMO) or death. A total 114 infants were included in this study. We investigated whether simplified prediction formula [PO2-PCO2] values at 0, 4, 8, and 12 hr after birth were associated with mortality, and ECMO or death. The area under curve (AUC) of receiver operating characteristic curve was used to determine the optimum ABGA values for predicting outcomes. The value of [PO2-PCO2] at birth was the best predictor of mortality (AUC 0.803, P < 0.001) and at 4 hr after birth was the most reliable predictor of ECMO or death (AUC 0.777, P < 0.001). The value of [PO2-PCO2] from ABGA early period after birth can reliably predict outcomes in infants with CDH.

A randomized controlled trial of fetal endoscopic tracheal occlusion versus postnatal management of severe isolated congenital diaphragmatic hernia

OBJECTIVE

Severe pulmonary hypoplasia and pulmonary arterial hypertension are associated with reduced survival in congenital diaphragmatic hernia (CDH). We aimed to determine whether fetal endoscopic tracheal occlusion (FETO) improves survival in cases of severe isolated CDH.

METHODS

Between May 2008 and July 2010, patients whose fetuses had severe isolated CDH (lung-to-head ratio < 1.0, liver herniation into the thoracic cavity and no other detectable anomalies) were assigned randomly to FETO or to no fetal intervention (controls). FETO was performed under maternal epidural anesthesia supplemented with fetal intramuscular anesthesia. Tracheal balloon placement was achieved with ultrasound guidance and fetoscopy between 26 and 30 weeks of gestation. All cases that underwent FETO were delivered by the EXIT procedure. Postnatal therapy was the same for both treated fetuses and controls. The primary outcome was survival to 6 months of age. Other maternal and neonatal outcomes were also evaluated.

RESULTS

Twenty patients were enrolled randomly to FETO and 21 patients to standard postnatal management. The mean gestational age at randomization was similar in both groups (P = 0.83). Delivery occurred at 35.6 ± 2.4 weeks in the FETO group and at 37.4 ± 1.9 weeks in the controls (P < 0.01). In the intention-to-treat analysis, 10/20 (50.0%) infants in the FETO group survived, while 1/21 (4.8%) controls survived (relative risk (RR), 10.5 (95% CI, 1.5-74.7), P < 0.01). In the received-treatment analysis, 10/19 (52.6%) infants in the FETO group and 1/19 (5.3%) controls survived (RR, 10.0 (95% CI, 1.4-70.6) P < 0.01).

CONCLUSION

FETO improves neonatal survival in cases with isolated severe CDH.

Perioperative course of pulmonary hypertension in infants with congenital diaphragmatic hernia: impact on outcome following successful repair

BACKGROUND

Pulmonary hypertension (PH) associated with congenital diaphragmatic hernia (CDH) remains a significant cause of morbidity and mortality. For improved outcomes, preoperative stabilization is commonly practiced to control the PH in infants with CDH. Some CDH infants who have been considered stabilized and ready for surgery have nevertheless developed significant PH after surgical repair. In fact, the markers and consequences of the preoperative stabilization are still unclear. Therefore, we examine the perioperative course of PH to evaluate the impact of preoperative PH severity on mortality and morbidity of infants who underwent surgical repair of CDH.

METHODS

The medical charts of all newborns (n = 49) with CDH who were treated at our institution between January 2000 and December 2009 were reviewed. General management and perioperative data were evaluated for all infants. The ratio of estimated pulmonary artery pressure to systemic pressure (P/S ratio or PSR), based on echocardiographic data, was used to assess the PH severity during the perioperative period.

RESULTS

The overall survival rate in our group of infants with CDH was 71.4%. Of the 49 infants with CDH, 9 (18.4%) died during the preoperative phase. Forty infants underwent CDH repair at a median age of 3.5 days (range, 1-46 days). Five of these infants (12.5%) subsequently deteriorated and died after surgery. Using receiver operating characteristic curve analysis, a PSR cutoff value before surgery of 0.9 predicted mortality in CDH infants with a sensitivity of 100% and specificity of 84% and with an area under the curve of 0.93 (P = .002). Accordingly, 2 groups of infants with distinct outcomes were identified, as follows: a low-PSR cohort (PSR ≤0.9) with a survival rate of 100% and a high-PSR cohort (PSR >0.9) with a survival rate of 50% (P = .001). The rate of pneumothorax and the frequency of use of several inotropic agents after surgery were significantly higher in the high-PSR group (P = .001 and .007, respectively). Compared with low-PSR infants, infants with high PSR were operated on later (P = .03) and were postoperatively ventilated longer (P = .01). During the entire perioperative period, significant differences in the PH severity were noted between the 2 PSR groups. During the first week of life, infants in the high-PSR group had significantly higher PSRs than those in the low-PSR group (P = .001); and similar tendencies continued to be significant between the 2 groups after CDH repair (P = .04).

CONCLUSIONS

During the perioperative period, PH severity monitoring via the serial assessment of PSR is beneficial. Better outcomes were observed with a preoperative PSR less than or equal to 0.9, and this association needs to be confirmed by prospective study.

Re-evaluation of stomach position as a simple prognostic factor in fetal left congenital diaphragmatic hernia: a multicenter survey in Japan

OBJECTIVES

To document outcome and to explore prognostic factors in fetal left congenital diaphragmatic hernia (CDH).

METHODS

This was a multicenter retrospective study of 109 patients with prenatally diagnosed isolated left CDH born between 2002 and 2007. The primary outcome was intact discharge, defined as discharge from hospital without major morbidities, such as a need for respiratory support including oxygen supplementation, tube feeding, parenteral nutrition or vasodilators. All patients were managed at perinatal centers with immediate resuscitation, gentle ventilation (mostly with high-frequency oscillatory ventilation) and surgery after stabilization. Prenatal data collected included liver and stomach position, lung-to-head ratio, gestational age at diagnosis and presence or absence of polyhydramnios. Stomach position was classified into four grades: Grade 0, abdominal; Grade 1, left thoracic; Grade 2, less than half of the stomach herniated into the right chest; and Grade 3, more than half of the stomach herniated into the right chest.

RESULTS

Overall intact discharge and 90-day survival rates were 65.1% and 79.8%, respectively. Stomach herniation was classified as Grade 0 in 19.3% of cases, Grade 1 in 45.9%, Grade 2 in 13.8% and Grade 3 in 21.1%. Multivariate analysis revealed that liver position was the strongest prognostic variable for intact discharge, followed by stomach position. Based on our results, we divided patients into three groups according to liver (up vs. down) and stomach (Grade 0-2 vs. Grade 3) position. Intact discharge rates declined significantly from liver-down (Group I), to liver-up with stomach Grade 0-2 (Group II), to liver-up with stomach Grade 3 (Group III) (87.0%, 47.4% and 9.5% of cases, respectively).

CONCLUSION

Current status and outcomes of prenatally diagnosed left CDH in Japan were surveyed. Stomach herniation into the right chest was not uncommon and its grade correlated with outcome. The combination of liver and stomach positions was useful to stratify patients into three groups (Group I-III) with different prognoses.

Early repair of congenital diaphragmatic hernia on extracorporeal membrane oxygenation

BACKGROUND

Timing of repair of congenital diaphragmatic hernia (CDH) in babies that require stabilization on extracorporeal membrane oxygenation (ECMO) remains controversial. Although many centers delay operation until physiologic stabilization has occurred or ECMO is no longer needed, we repair soon after ECMO has been initiated. The purpose of this study is to determine if our approach has achieved acceptable morbidity and mortality.

METHODS

Charts of live-born babies with CDH treated at our institution between 1993 and 2007 were retrospectively reviewed. Data were then compared with The Congenital Diaphragmatic Hernia Study Group and Extracorporeal Life Support Organization registries.

RESULTS

Forty-eight (39%) patients required ECMO Thirty-four of these 48 neonates were cannulated before operative repair. Venoarterial ECMO was used exclusively. The mean (SD) time of repair from cannulation was 55 (21) hours. Survival for this subset of patients was 71%. Three patients (8.8%) who underwent repair on ECMO experienced surgical site hemorrhage that required intervention.

CONCLUSION

Early repair of CDH in neonates on ECMO can be accomplished with acceptable rates of morbidity and mortality.

Congenital diaphragmatic hernia: prognostic indices in the fetal endoluminal tracheal occlusion era

INTRODUCTION

Management of congenital diaphragmatic hernia (CDH) in the UK now includes the possibility of fetal endoluminal tracheal occlusion (FETO) for poor prognosis fetuses. The objective of this study was to investigate the value of variables previously thought prognostic in the FETO era.

METHODS

A retrospective single-centre study was performed of all infants with CDH born between January 1994 and December 2007. Fetal endoluminal tracheal occlusion was available and had been used with parental consent for fetuses with lung-to-head ratio (LHR) of 1.0 or less and a liver-up position from 2002. Univariate analysis was used to predict survival (to leave hospital) using both prenatal (eg, polyhydramnios) and perinatal variables [eg, best oxygenation index on day 1, or BOI (d1)] and their dependence tested in a logistic regression model. Data were quoted as medians (range). P < .05 was regarded as significant.

RESULTS

Eighty-six infants with CDH (1994-2002, n = 35 and 2002-2007, n = 51 "FETO era") were studied. Successful FETO intervention was performed in 31 infants. Univariate analysis showed liver position, birth weight, LHR, and BOI (d1) were significant prognostic predictors (all P < .05); however, only BOI (d1) retained significance using logistic regression analysis (odds ratio, 21; 95% confidence interval, 6-74; P < .001). Best oxygenation index on day 1 was then used as a surrogate marker for outcome to test the relationship with LHR (available since 2002) and showed a significant inverse correlation (r(s) = -0.5; P < .001). There was no difference in median BOI (d1) between the FETO group and all those treated expectantly (40 [34-1046] vs 59 (23-581); P = .3].

CONCLUSION

Best oxygenation index on day 1 is the best early postnatal predictor of survival. The more recently evaluated prenatal index, LHR, has an observable relationship with BOI (d1) when it is used as a surrogate marker of outcome.