Predictors of successful extubation of preterm low-birth-weight infants with respiratory distress syndrome

Predictors of Extubation Failure in Very Low Birth Weight Infants at a Tertiary Care Hospital in Al Ain: A Retrospective Study

OBJECTIVES

To identify and analyze the factors leading to extubation failure among very low birth weight infants in a specific tertiary care setting in Al Ain, emphasizing clinical and demographic variables. The study used medical data of Very Low Birth Weight (VLBW) infants admitted to the Neonatal Intensive Care Unit (NICU) from 1st January 2015 to 31st December 2019, and evaluated the incidence and risk factors associated with extubation failure.

METHODS

Data was collected from the hospital's electronic records and tabulated in Excel sheets, with extubation failure defined as reintubation due to deterioration of respiratory condition within seven days post-extubation. The data was collected from the period of 1st January 2015 to 31st December 2019. Inclusion criteria included babies admitted to the NICU with a gestational age of ≤ 32 weeks, or of birth weight ≤1500 grams who were intubated within the first seven days of life. Results were analyzed using SPSS software, version 9.0 (SPSS Inc., Chicago) to determine the risk factors for extubation failure and short-term outcomes.

RESULTS

Gestational age, birth weight, antenatal steroids, mode of delivery, number of Survanta® (beractant intratracheal suspension) doses, Positive End-Expiratory Pressure (PEEP), Mean Airway Pressure (MAP), Mean Arterial Pressure (Blood Pressure (BP)), and Infectious Diseases (ID) (indicated by a positive blood culture) were found to be the key predictors of extubation failure in very low birth weight infants at a tertiary care hospital in Al Ain. The most common reasons for reintubation were FiO2 > 50% (23.53%), followed by Respiratory Acidosis (20.59%). Other factors, including maternal chorioamnionitis, Apgar scores, indication for intubation, caffeine, and pre-and post-extubation laboratory values, comorbidities, and hemoglobin (Hgb), creatinine and sodium levels were found to have no effect on the success of extubations.

CONCLUSIONS

The results of this research indicate that factors such as gestational age, birth weight, prenatal steroid use, delivery method, the quantity of Survanta® doses, PEEP, MAP, MAP (BP), and ID (+ve blood culture) were the primary determinants of unsuccessful extubation in VLBW babies at a tertiary healthcare facility in Al Ain. The predominant cause for needing reintubation was a FiO2 level above 50%, followed by Respiratory Acidosis. Additional ®®investigations are required to validate these findings and pinpoint other potential predictors of extubation failure within this demographic.

Prediction of extubation failure among low birthweight neonates using machine learning

OBJECTIVE

To develop machine learning models predicting extubation failure in low birthweight neonates using large amounts of clinical data.

STUDY DESIGN

Retrospective cohort study using MIMIC-III, a large single-center, open-source clinical dataset. Logistic regression and boosted-tree (XGBoost) models using demographics, medications, and vital sign and ventilatory data were developed to predict extubation failure, defined as reintubation within 7 days.

RESULTS

1348 low birthweight (≤2500 g) neonates who received mechanical ventilation within the first 7 days were included, of which 350 (26%) failed a trial of extubation. The best-performing model was a boosted-tree model incorporating demographics, vital signs, ventilator parameters, and medications (AUROC 0.82). The most important features were birthweight, last FiO2, average mean airway pressure, caffeine use, and gestational age.

CONCLUSIONS

Machine learning models identified low birthweight ventilated neonates at risk for extubation failure. These models will need to be validated across multiple centers to determine generalizability of this tool.

Risk Factors of Extubation Failure in Intubated Preterm Infants at a Tertiary Care Hospital in Oman

Objectives

This study aimed to determine extubation failure (EF) rate among intubated preterm infants (<37 weeks gestational age [GA]) admitted to a tertiary care neonatal intensive care unit (NICU) in Oman and identify the risk factors associated with EF.

Methods

This retrospective study included all intubated preterm infants (<37 weeks GA) admitted to the NICU at Sultan Qaboos University Hospital (SQUH) from January 2013 to December 2017. EF was defined as reintubation within seven days of planned extubation. Demographics, ventilation parameters, blood gas values and other possible risk factors of EF were collected. Statistical analysis included comparisons between EF and extubation success (ES) groups and a binary logistic regression analysis.

Results

A total of 190 preterm infants were intubated during the study period with 140 eligible for analysis. A total of 106 infants (75.7%) were successfully extubated while 34 (24.3%) failed extubation. GA <28 weeks (P = 0.029), lower 1-minute Apgar score (P = 0.023) and patent ductus arteriosus diagnosis (P = 0.018) were significantly associated with EF. After the multivariate analysis, only GA <28 weeks predicted EF with an adjusted odds ratio of 2.621 (95% confidence interval: 1.118 - 6.146).

Conclusion

EF rate in preterm infants admitted at the NICU of SQUH was within international rates. GA <28 weeks was the only predictor of the identified extubation failure. Neonatal practitioners need to seriously consider extreme prematurity in the extubation process and consider implementing strategies to decrease extubation failure in this group of fragile infants.

The DELUX study: development of lung volumes during extubation of preterm infants

OBJECTIVE

To measure changes in end-expiratory lung impedance (EELI) as a marker of functional residual capacity (FRC) during the entire extubation procedure of very preterm infants.

METHODS

Prospective observational study in preterm infants born at 26-32 weeks gestation being extubated to non-invasive respiratory support. Changes in EELI and cardiorespiratory parameters (heart rate, oxygen saturation) were recorded at pre-specified events during the extubation procedure compared to baseline (before first handling of the infant).

RESULTS

Overall, 2912 breaths were analysed in 12 infants. There was a global change in EELI during the extubation procedure (p = 0.029). EELI was lowest at the time of extubation [median (IQR) difference to baseline: -0.30 AU/kg (-0.46; -0.14), corresponding to an FRC loss of 10.2 ml/kg (4.8; 15.9), p_adj = 0.004]. The biggest EELI loss occurred during adhesive tape removal [median change (IQR): -0.18 AU/kg (-0.22; -0.07), p_adj = 0.004]. EELI changes were highly correlated with changes in the SpO₂/FiO₂ ratio (r = 0.48, p < 0.001). Forty per cent of FRC was re-recruited at the tenth breath after the initiation of non-invasive ventilation (p < 0.001).

CONCLUSIONS

The extubation procedure is associated with significant changes in FRC. This study provides novel information for determining the optimal way of extubating a preterm infant.

IMPACT

This study is the first to examine the development of lung volumes during the entire extubation procedure including the impact of associated events. The extubation procedure significantly affects functional residual capacity with a loss of approximately 10 ml/kg at the time of extubation. Removal of adhesive tape is the major contributing factor to FRC loss during the extubation procedure. Functional residual capacity is regained within the first breaths after initiation of non-invasive ventilation and is further increased after turning the infant into the prone position.

Extubation Readiness in Preterm Infants: Evaluating the Role of Monitoring Intermittent Hypoxemia

Preterm infants with respiratory distress may require mechanical ventilation which is associated with increased pulmonary morbidities. Prompt and successful extubation to noninvasive support is a pressing goal. In this communication, we show original data that increased recurring intermittent hypoxemia (IH, oxygen saturation <80%) may be associated with extubation failure at 72 h in a cohort of neonates <30 weeks gestational age. Current-generation bedside high-resolution pulse oximeters provide saturation profiles that may be of use in identifying extubation readiness and failure. A larger prospective study that utilizes intermittent hypoxemia as an adjunct predictor for extubation readiness is warranted.

Predicting extubation outcomes using the Heart Rate Characteristics index in preterm infants: a cohort study

A strategy of early extubation to noninvasive respiratory support in preterm infants could be boosted by the availability of a decision support tool for clinicians. Using the Heart Rate Characteristics index (HRCi) with clinical parameters, we derived and validated predictive models for extubation readiness and success.Peri-extubation demographic, clinical and HRCi data for up to 96 h were collected from mechanically ventilated infants in the control arm of a randomised trial involving eight neonatal centres, where clinicians were blinded to the HRCi scores. The data were used to produce a multivariable regression model for the probability of subsequent re-intubation. Additionally, a survival model was produced to estimate the probability of re-intubation in the period after extubation.Of the 577 eligible infants, data from 397 infants (69%) were used to derive the pre-extubation model and 180 infants (31%) for validation. The model was also fitted and validated using all combinations of training (five centres) and test (three centres) centres. The estimated probability for the validation episodes showed discrimination with high statistical significance, with an area under the curve of 0.72 (95% CI 0.71-0.74; p<0.001). Data from all infants were used to derive models of the predictive instantaneous hazard of re-intubation adjusted for clinical parameters.Predictive models of extubation readiness and success in real-time can be derived using physiological and clinical variables. The models from our analyses can be accessed using an online tool available at www.heroscore.com/extubation, and have the potential to inform and supplement the confidence of the clinician considering extubation in preterm infants.

Use of extubation bundle including modified spontaneous breathing trial (SBT) to reduce the rate of reintubation, among preterm neonates ≤ 30 weeks

BACKGROUND

Respiratory support in the form of mechanical ventilation is a crucial intervention in premature neonates, with respiratory problems. However, prolonged mechanical ventilation and endotracheal intubation may be associated with major adverse effects. The ideal time for extubation is based on clinical and laboratory parameters assessed at the time of planned extubation. However, such parameters are not very objective, which makes extubation in NICUs a trial-and-error approach.

OBJECTIVE

This work was done to assess the use of extubation bundle including modified spontaneous breathing trial (SBT) (10 minutes) to reduce the rate of reintubation, among preterm neonates≤30 weeks who were mechanically ventilated and extubated to non-invasive ventilation in the NICU, Women's Wellness and Research Center (WWRC), Hamad Medical Corporation (HMC), Doha, Qatar.

METHODS

A prospective study based on the collection of data regarding preterm neonates≤30 weeks gestation admitted to the NICU, Women's Wellness and Research Center (WWRC), from January, 2015 to December, 2017, who were subjected to mechanical ventilation (MV) and extubation. When the clinical team decides a newborn is ready for extubation based on the extubation bundle, a modified SBT (10 min) is used.

RESULTS

This study included 465 premature babies from 24-≤30 weeks recruited in the NICU, Women's Wellness and Research Center (WWRC). Extubation bundle with modified SBT was able to predict success of extubation with 95% sensitivity and 90.4% Positive Predictive Value (PPV) in the gestational age (GA) group 24 -≤27 weeks (245) and 95.3% sensitivity and 90% PPV in the GA group > 27 -≤30 weeks (220). As expected, successfully extubated babies had a higher GA and weighed more at extubation, compared to babies who required re-intubation.

CONCLUSION

We recommend the extubation bundle with modified SBT prior to elective extubation to be used in predicting successful extubation in premature babies. Guidelines for extubation among premature babies are needed in order to reduce unnecessary exposure to adverse effects of mechanical ventilation.

Effects of an extubation readiness test protocol at a tertiary care fully outborn neonatal intensive care unit

Background and objectives

Extubation readiness testing (ERT) in the Neonatal Intensive Care Unit (NICU) is highly variable and lacking standardized criteria. To address this gap, an evidence-based, inter-professionally developed ERT protocol was implemented to assess effectiveness on extubation failure within 72 h and on duration of intubation (DOI).

Methods

A longitudinal retrospective chart review in a level III, fully outborn NICU, of intubated infants admitted 1-year prior (Group 1), and 1 year after implementation (Group 2). Patients were extubated if they passed a 2-stage ERT protocol (3 min continuous positive airway pressure (CPAP) followed by 7 min CPAP + pressure support). Descriptive, comparative statistics, and univariate and multiple logistic regression were completed on all patients and a ≤32 6/7 weeks subgroup (intubated at day-of-life 1); p < 0.05 is considered significant.

Results

All patients (n = 589 (n = 294 Group 1, n = 295 Group 2)) were included (preterm, intubated day of life one subgroup: n = 42 Group 1, n = 38 Group 2). For all patients, extubation failure decreased significantly from 9.9% to 4.1% (p = 0.006); Group 1 patients were 2.42 times more likely to experience extubation failure compared with Group 2. Extubation failure in the preterm subgroup decreased from 21.7% to 2.6% (p = 0.01); Group 1 patients were 10.71 times more likely to experience extubation failure. Median DOI was similar in both groups for all patients and in the preterm subgroup.

Conclusions

A unique two-stage ERT protocol was effective at reducing extubation failure rate, without increasing DOI, largely in preterm infants. The evidence-based, interprofessionally developed ERT protocol and its integration into the NICU culture largely contributed to its success.

Predicting Extubation Outcomes-A Model Incorporating Heart Rate Characteristics Index

OBJECTIVE

To test the hypothesis that in neonates on mechanical ventilation, heart rate characteristics index (HRCi) can be combined with a clinical model for predicting extubation outcomes in neonates.

STUDY DESIGN

HRCi and clinical data for all intended intubation-extubation events (episodes) were retrospectively analyzed between June 2014 and January 2015. Each episode started 6 hours pre-extubation or at the time of primary intubation if ventilation duration was shorter than 6 hours (baseline). The episodes ended at 72 hours postextubation for successful extubations or at reintubation for failed extubations. Mean of 6 hourly epoch HRCi-scores (baseline) or fold-changes (postextubation) were analyzed. Results are expressed as medians (IQR) for continuous data and proportions for categorical data. Multivariable logistic regression mixed model was used for statistical analysis.

RESULTS

Sixty-six infants contributed to 96 episodes (18 failed extubations, 78 successful extubations) in the study. Failed extubations had significantly longer duration of ventilation (65.3 hours, 19.94-158.2 vs 38.4, 16.5-71.3) and more culture positive sepsis (33.3% vs 3.8%) than successful extubations. Baseline HRCi scores (1.68, 1.29-2.45 vs 0.95, 0.54-1.86) and postextubation epoch-1 fold changes (1.25, 0.94-1.55 vs 0.94, 0.82-1.11) were higher in failed extubations compared with successful extubations. Multivariable linear mixed-effects regression was used to create prediction models for success of extubation, using relevant variables.

CONCLUSIONS

The baseline and postextubation HRCi were significantly higher in neonates with extubation failure compared with those who succeeded. Models using HRCi and clinical variables to predict extubation success may add to the confidence of clinicians considering extubation.

Extubation from high-frequency oscillatory ventilation in extremely low birth weight infants: a prospective observational study

OBJECTIVE

To evaluate if weaning from high-frequency oscillatory ventilation (HFOV) directly to a non-invasive mode of respiratory support is feasible and results in successful extubation in extremely low birth weight (ELBW) infants.

DESIGN

Prospective observational study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

One hundred and eight ELBW infants of 26.2±1.4 weeks of gestational age (GA) directly extubated from HFOV.

INTERVENTIONS

All infants were managed with elective HFOV and received surfactant after a recruitment HFOV manoeuvre. Extubation was attempted at mean airways pressure (MAP) ≤6 cm H₂O with FiO₂ ≤0.25. After extubation, all infants were supported by nasal continuous positive airway pressure (6-8 cm H₂O).

MAIN OUTCOME MEASURES

Extubation failure (clinical deterioration requiring reintubation) was defined as shorter than 7 days.

RESULTS

Ninety patients (83%) were successfully extubated and 18 (17%) required reintubation. No significant differences were found between the two groups in terms of birth weight, day of life and weight at the time of extubation. Multivariable analysis showed that GA (OR 1.71; 95% CI 1.04, 2.08) and higher MAP prior to surfactant (OR 1.51; 95% CI 1.06, 2.15) were associated with successful extubation.

CONCLUSIONS

In ELBW infants, direct extubation from HFOV at MAP ≤6 cm H₂O with FiO₂ ≤0.25 is feasible. Our extubation success rate (83%) is higher than conventional mechanical ventilation in this very vulnerable class of infants.

Risk Factors for Extubation Failure in Extremely Low Birth Weight Infants

BACKGROUND

Although antenatal steroids and early use nasal continuous positive airway pressure (NCPAP) have significantly improved outcomes of neonatal respiratory distress syndrome, intubation with ventilator support is still commonly required in extremely low birth weight (ELBW) infants. The optimal timing of extubation in ELBW infants remains unclear.

METHODS

We retrospectively analyzed all ELBW preterm infants who were admitted to our neonatal intensive care unit (NICU) from January 2009 to December 2013. Demographic, ventilation, and arterial blood gas analysis results prior to and 2 hours after extubation were collected. Extubation failure was defined as reintubation due to deterioration of respiratory condition within 7 days after extubation. Risk factors for extubation failure were analyzed.

RESULTS

In total, 173 ELBW infants were born and admitted to our NICU during these 5 years. Among these 173 infants, 77 (44.5%) used NCPAP only during their hospitalization (20 diagnosed with chronic lung disease (CLD), 25.9%). Among the 95 patients that required intubation, 27 patients expired so extubation was not attempted. Sixteen of 68 (23.5%) survival cases required reintubation within 7 days after extubation. We found that gestational age, birth body weight, and sex ratio did not differ between the successful extubation group and the failed extubation group. Univariate analysis showed that the failed extubation group had a lower arterial pH right before and 2 hours after extubation, with a lower bicarbonate level after extubation. Further multivariate logistic regression analysis revealed an association between poor acid-base homeostasis 2 hours after extubation (pH < 7.3 and HCO₃ < 18 mM/L) and extubation failure (odds ratio 4.56 and 6.187 and 95% confidence interval: 1.263∼16.462 and 1.68∼22.791, respectively).

CONCLUSION

This study shows that nearly half of ELBW infants do not require intubation. Among ELBW infants who require invasive ventilator support, those who have lower postextubation arterial pH and bicarbonate levels are at high risk of extubation failure.

A new infant hybrid respiratory simulator: preliminary evaluation based on clinical data

A new hybrid (numerical-physical) simulator of the respiratory system, designed to simulate spontaneous and artificial/assisted ventilation of preterm and full-term infants underwent preliminary evaluation. A numerical, seven-compartmental model of the respiratory system mechanics allows the operator to simulate global and peripheral obstruction and restriction of the lungs. The physical part of the simulator is a piston-based construction of impedance transformer. LabVIEW real-time software coordinates the work of both parts of the simulator and its interaction with a ventilator. Using clinical data, five groups of "artificial infants" were examined: healthy full-term infants, very low-birth-weight preterm infants successfully (VLBW) and unsuccessfully extubated (VLBWun) and extremely low-birth-weight preterm infants without (ELBW) and with bronchopulmonary dysplasia (ELBW_BPD). Pressure-controlled ventilation was simulated to measure peak inspiratory pressure, mean airway pressure, total (patient + endotracheal tube) airway resistance (R), total dynamic compliance of the respiratory system (C), and total work of breathing by the ventilator (WOB). The differences between simulation and clinical parameters were not significant. High correlation coefficients between both types of data were obtained for R, C, and WOB (γ _R  = 0.99, P < 0.0005; γ _C  = 0.85, P < 0.005; γ_WOB = 0.96, P < 0.05, respectively). Thus, the simulator accurately reproduces infant respiratory system mechanics.

Extubating Extremely Preterm Infants: Predictors of Success and Outcomes following Failure

OBJECTIVES

To identify variables that predict extubation success in extremely preterm infants born <28 weeks gestational age (GA), and to compare outcomes between those who had successful or failed extubation.

STUDY DESIGN

A secondary analysis of data from a randomized trial of postextubation respiratory support that included 174 extremely preterm infants. "Extubation success" was defined as not requiring reintubation within 7 days, and "extubation failure" the converse. Predictive variables that were different between groups were included in a multivariable logistic regression model.

RESULTS

Sixty-eight percent of infants were successfully extubated. Compared with those infants who had extubation failure, they had a higher GA and birth weight, were extubated earlier, were more often exposed to prolonged ruptured membranes, more often avoided intubation in the delivery room, had a higher pre-extubation pH, and had lower mean pre-extubation fraction of inspired oxygen and partial pressure of carbon dioxide (PCO2). Only GA and PCO2 remained significant in the multivariable analysis (area under a receiver operating characteristic curve = 0.81). Extubation failure was associated with death, bronchopulmonary dysplasia, severe retinopathy of prematurity, patent ductus arteriosus ligation, and longer durations of respiratory support, oxygen supplementation, and hospitalization. When adjusted for allocated treatment in the randomized trial, GA, and birth weight z-score, extubation failure remained associated with death before discharge and prolonged respiratory support and hospitalization.

CONCLUSIONS

In extremely preterm infants, higher GA and lower pre-extubation PCO2 predicted extubation success. Infants in whom extubation failed were more likely to die and have prolonged respiratory support and hospitalization.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Network: ACTRN12610000166077.

Factors affecting nasal intermittent positive pressure ventilation failure and impact on bronchopulmonary dysplasia in neonates

BACKGROUND

Nasal intermittent positive pressure ventilation (NIPPV) is becoming more important as a mode of ventilation in premature neonates predisposed to development of bronchopulmonary dysplasia (BPD). To the best of our knowledge, there have been no detailed studies characterizing neonates who fail NIPPV.

OBJECTIVE

To determine the differences between neonates who are successfully extubated to NIPPV and those who require re-intubation from NIPPV, and the impact of timing of NIPPV failure on BPD rates.

STUDY DESIGN

This was a retrospective cohort study in which we included infants with gestational age (GA) ⩽ 28 weeks and birth weight ⩽ 1000 g. χ²-test, analysis of variance and multivariate logistic regression models were used.

RESULTS

Two hundred and forty infants were studied; 180 failed NIPPV and of those, 33 (18%), 39 (22%) and 108 (60%) failed NIPPV within 0 to 6 h, ⩾ 6 to 24 h and ⩾ 24 h, respectively. Female sex and increased weight were protective against NIPPV failure (adjusted odds ratio (95% confidence interval): 0.28 (0.14 to 0.58), 0.04 (0.01 to 0.22)). Increased GA at extubation and female sex were both associated with increased time to failure (P=0.008, <0.001, respectively). Apnea was more likely the cause for failure ⩾ 24 h (P=0.015), whereas increased work of breathing/fraction of inspired oxygen requirements were more significant when NIPPV failure occurred earlier (P=0.001). Neonates who failed NIPPV within 24 h did not have any association with likelihood of developing BPD or severity of BPD, after adjusting for confounding variables.

CONCLUSION

Significant differences in neonatal characteristics may help identify which neonates are more likely to fail NIPPV, and their timing of failure.

Prediction of extubation failure for neonates with respiratory distress syndrome using the MIMIC-II clinical database

Extubation failure (EF) is an ongoing problem in the neonatal intensive care unit (NICU). Nearly 25% of neonates fail their first extubation attempt, requiring re-intubations that are associated with risk factors and financial costs. We identified 179 mechanically ventilated neonatal patients that were intubated within 24 hours of birth in the MIMIC-II intensive care database. We analyzed data from the patients 2 hours prior to their first extubation attempt, and developed a prediction algorithm to distinguish patients whose extubation attempt was successful from those that had EF. From an initial list of 57 candidate features, our machine learning approach narrowed down to six features useful for building an EF prediction model: monocyte cell count, rapid shallow breathing index, fraction of inspired oxygen (FiO(2)), heart rate, PaO(2)/FiO(2) ratio where PaO(2) is the partial pressure of oxygen in arterial blood, and work of breathing index. Algorithm performance had an area under the receiver operating characteristic curve (AUC) of 0.871 and sensitivity of 70.1% at 90% specificity.

Role of spontaneous breathing trial in predicting successful extubation in premature infants

BACKGROUND

The ability of clinicians to predict successful extubation in mechanically ventilated premature neonates is limited. Identifying objective criteria for predicting successful extubation may reduce the incidence of failed extubation and the duration of mechanical ventilation.

OBJECTIVE

To evaluate the validity of objective measures of lung function and spontaneous breathing trial (SBT) in predicting successful extubation among premature neonates with attempted extubations within the first 3 weeks of life.

METHODS

Respiratory compliance (Crs) along with SBT was performed prior to elective extubations within 3 weeks of age in premature infants ≤ 32 weeks. Extubation was considered successful if patients remained extubated for > 72 hr. Ventilator settings including mean airway pressure (MAP), set rate, and fraction of inspired oxygen (FiO₂) 24 hr after re-intubation were compared with pre-extubation settings, in patients requiring re-intubation.

RESULTS

Thirty-nine of 49 infants (80%) were successfully extubated. Of 41 babies who passed SBT, only 5 infants failed extubation. SBT had 92% sensitivity, 50% specificity, 88% positive predictive, and 63% negative predictive value for successful extubation. Crs was comparable between infants who were successfully extubated and those who were not.

CONCLUSIONS

A SBT prior to extubation may be a practical objective adjunct in predicting successful extubation in ventilated premature infants.

Inspiratory capacity at inflation hold in ventilated newborns: a surrogate measure for static compliance of the respiratory system

OBJECTIVE

To study appropriateness of respiratory system compliance calculation using an inflation hold and compare it with ventilator readouts of pressure and tidal volume as well as with measurement of compliance of the respiratory system with the single-breath-single-occlusion technique gained with a standard lung function measurement.

DESIGN

Prospective clinical trial.

SETTING

Level III neonatal unit of a university hospital.

SUBJECTS

Sixty-seven newborns, born prematurely or at term, ventilated for a variety of pathologic conditions.

INTERVENTIONS

A standardized sigh maneuver with a predefined peak inspiratory pressure of 30 cm H2O, termed inspiratory capacity at inflation hold, was applied. Using tidal volume, exhaled from inspiratory pause down to ambient pressure, as displayed by the ventilator, and predefined peak inspiratory pressure, compliance at inspiratory capacity at inflation hold conditions could be calculated as well as ratio of tidal volume and ventilator pressure using tidal volume and differential pressure at baseline ventilator settings: peak inspiratory pressure minus positive end-expiratory pressure.

MEASUREMENTS AND MAIN RESULTS

For the whole cohort, the equation for the regression between tidal volume at inspiratory capacity at inflation hold and compliance of the respiratory system was: compliance of the respiratory system = 0.052 * tidal volume at inspiratory capacity at inflation hold - 0.113, and compliance at inspiratory capacity at inflation hold conditions was closely related to the standard lung function measurement method of compliance of the respiratory system (R = 0.958). In contrast, ratio of tidal volume and ventilator pressure per kilogram calculated from the ventilator readouts and displayed against compliance of the respiratory system per kilogram yielded a broad scatter throughout the whole range of compliance; both were only weakly correlated (R = 0.309) and also the regression line was significantly different from the line of identity (p < .05). Peak inspiratory pressure at study entry did not affect the correlation between compliance at inspiratory capacity at inflation hold conditions and compliance of the respiratory system.

CONCLUSIONS

After a standard sigh maneuver, inspiratory capacity at inflation hold and the derived quantity compliance at inspiratory capacity at inflation hold conditions can be regarded as a valid, accurate, and reliable surrogate measure for standard compliance of the respiratory system in contrast to ratio of tidal volume and ventilator pressure calculated from the ventilator readouts during ongoing mechanical ventilation at respective ventilator settings.

Weaning infants from mechanical ventilation

Protracted mechanical ventilation is associated with increased morbidity and mortality in preterm infants and thus the earliest possible weaning from mechanical ventilation is desirable. Weaning protocols may be helpful in achieving more rapid reduction in support. There is no clear consensus regarding the level of support at which an infant is ready for extubation. An improved ability to predict when a preterm infant has a high likelihood of successful extubation is highly desirable. In this article, available evidence is reviewed and reasonable evidence-based recommendations for expeditious weaning and extubation are provided.

Implementation of a neonatal pain management module in the computerized physician order entry system

BACKGROUND

Despite the recommended guidelines, the neonatal management of pain and discomfort often remains inadequate. The purpose of the present study was to determine whether adding a pain and discomfort module to a computerized physician order entry (CPOE) system would improve pain and discomfort evaluation in premature newborns under invasive ventilation.

METHODS

All newborns <37 weeks gestational age (GA) and requiring invasive ventilation were included in a prospective study during two 6-month periods: before and after the inclusion of the pain and discomfort evaluation module. The main outcome measure was the percentage of patients having at least one assessment of pain and discomfort per day of invasive ventilation using the COMFORT scale.

RESULTS

A total of 122 patients were included: 53 before and 69 after the incorporation of the module. The mean age was 30 (3) weeks GA. After the module was included, the percentage of patients who benefited from at least one pain and discomfort assessment per day increased from 64% to 88% (p < 0.01), and the mean number (SD) of scores recorded per day increased from 1 (1) to 3 (1) (p < 0.01). When the score was not within the established range, the nursing staff adapted analgesia/sedation doses more frequently after module inclusion (53% vs. 34%, p < 0.001). Despite higher mean doses of midazolam after module introduction [47 (45) vs. 31 (18) μg/kg/hr, p < 0.05], the durations of invasive ventilation and hospital stay, and the number of nosocomial infections, were not significantly modified.

CONCLUSIONS

Adding a pain and discomfort tool to the CPOE system was a simple and effective way to improve the systematic evaluation of premature newborns who required ventilatory assistance.

[Recommendations for respiratory support in the newborn]

The recommendations included in this document will be part a series of updated reviews of the literature on respiratory support in the newborn infant. These recommendations are structured into twelve modules, with modules 4, 5, and 6 presented here. Each module is the result of a consensus process of all members of the Surfactant and Respiratory Group of the Spanish Society of Neonatology. They represent a summary of the published papers on each specific topic, and of the clinical experience of each one of the members of the group. Each module includes a summary of the scientific evidence available, graded into 4 levels of recommendations.

Work of breathing and different levels of volume-targeted ventilation

OBJECTIVES

The objectives of this study were to determine the impact of different volume-targeted levels on the work of breathing and to investigate whether a level that reduced the work of breathing below that experienced during ventilatory support without volume targeting could be determined.

METHODS

The transdiaphragmatic pressure-time product, as an estimate of the work of breathing, was measured for 20 infants (median gestational age: 28 weeks) who were being weaned from respiratory support by using patient-triggered ventilation (either assist-control ventilation or synchronous intermittent mandatory ventilation). The transdiaphragmatic pressure-time product was measured first without volume targeting (baseline) and then at volume-targeted levels of 4, 5, and 6 mL/kg, delivered in random order. After each volume-targeted level, the infants were returned to baseline. Each step was maintained for 20 minutes.

RESULTS

The mean transdiaphragmatic pressure-time product was higher with volume targeting at 4 mL/kg in comparison with baseline, regardless of the patient-triggered mode. The transdiaphragmatic pressure-time product was higher at a volume-targeted level of 4 mL/kg in comparison with 5 mL/kg and at 5 mL/kg in comparison with 6 mL/kg. The mean work of breathing was below that at baseline only at a volume-targeted level of 6 mL/kg.

CONCLUSIONS

Low volume-targeted levels increase the work of breathing during volume-targeted ventilation. Our results suggest that, during weaning, a volume-targeted level of 6 mL/kg, rather than a lower level, could be used to avoid an increase in the work of breathing.

Feasibility of weaning and direct extubation from open lung high-frequency ventilation in preterm infants

OBJECTIVE

High-frequency ventilation (HFV) is increasingly used in preterm infants, but data on weaning and extubation are limited. We aimed to establish if weaning the continuous distending pressure (CDP) below 8 cm H2O and the Fio2 below 0.30 is feasible in preterm infants on open lung HFV and if these settings result in successful extubation.

DESIGN

Retrospective cohort study.

SETTING

Neonatal intensive care unit in a university hospital.

PATIENTS

Preterm infants ventilated and directly extubated from HFV between January 2003 and August 2005.

MEASUREMENTS AND MAIN RESULTS

Data on patient characteristics, ventilator settings, gas exchange, respiratory support after extubation and the number of patients failing extubation (i.e., reintubation within 48 hr) were retrospectively collected. Two hundred fourteen infants, accounting for 242 ventilation periods, were included in the study. The CDP, but not the Fio2, decreased significantly in the 24-hr period before extubation, resulting in a mean CDP of 6.8 +/- 1.6 cm H2O and a mean Fio2 of 0.25 at the time of extubation. At these settings, 193 (90%) infants were successfully extubated. Multivariate logistic regression analysis showed that birth weight was the only independent variable positively associated with successful extubation.

CONCLUSION

This study shows that weaning the CDP below 8 cm H2O with an Fio2 below 0.30 is feasible during open lung HFV and extubation at these settings can be successful in preterm infants. In our series, a 90% success rate was observed. The value of this approach should be prospectively compared with conventional weaning and extubation strategies.

Medida da freqüência respiratória e do volume corrente para prever a falha na extubação de recém-nascidos de muito baixo peso em ventilação mecânica

OBJETIVO: Verificar se a freqüência respiratória (FR), o volume corrente (VC) e a relação FR/VC poderiam prever a falha na extubação em recém-nascidos de muito baixo peso submetidos à ventilação mecânica. MÉTODOS: Estudo prospectivo, observacional, de recém-nascidos com idade gestacional <37 semanas, peso ao nascer <1.500g, ventilados desde o nascimento por 48 horas a 30 dias. Após a indicação da retirada da ventilação mecânica, o neonato foi colocado em pressão positiva contínua (CPAP) por via traqueal por dez minutos, avaliando-se FR, VC e relação FR/VC por meio de um pneumotacógrafo conectado entre a cânula traqueal e o circuito do ventilador. Em seguida, o recém-nascido foi extubado e colocado em CPAP nasal, considerando-se falha na extubação a necessidade de reintubação em 48 horas. RESULTADOS: Das 35 crianças estudadas, 20 (57%) foram extubadas com sucesso e 15 (43%) necessitaram de reintubação. A FR e a relação FR/VC tenderam a ser maiores no grupo que falhou na extubação; o VC foi similar nos dois grupos. A sensibilidade e a especificidade para falha na extubação foram, respectivamente, 50 e 67% para FR, 40 e 67% para o VC e 40 e 73% para a relação FR/VC. CONCLUSÕES: A FR, o VC e a relação FR/VC apresentaram baixa sensibilidade e especificidade para prever a falha na extubação em recém-nascidos de muito baixo peso.

Lung function measurements in a preterm animal model of respiratory failure: comparison of two different neonatal ventilators

A variety of ventilators are used in the NICU. Ventilator and lung function measures are often applied in weaning protocols or as outcome variables. The effect of different ventilators on these measures has not been well studied. Our objective was to compare ventilator and lung function measurements in a chronic preterm animal model managed with two different neonatal ventilators. Timed baboon pregnancies exposed to antenatal steroids were delivered by C/S at 125 days (term = 185 days). Infants were immediately intubated, given surfactant, and ventilated with low tidal volumes (4-6 ml/kg) for 6-14 days using well-defined protocols. One group was ventilated via InfantStar (IS) and the other by VIP-Bird (VIP). Physiologic and pulmonary function data were serially recorded with the VitalTrends plethysmography system. Between ventilator comparisons were made. InfantStar (IS) was used on 22 infants in 2002-03, VIP was used on 29 infants in 2004-05. No differences were found for gestation, birth weight, gender, paO(2), paCO(2), FiO(2), arterial/alveolar ratio, dynamic compliance, inspiratory resistance, or tidal volumes. From 24 to 336 h, peak and mean airway pressure, ventilator rate, and ventilatory efficiency index (VEI: PIP x R x CO(2)/1,000) were significantly greater in the VIP group at multiple time points. VIP use was associated with a significant increase in expiratory airway resistance (Rexp - cmH(2)O/L/s) at all but one-time points studied. Compared to the IS, use of the VIP-Bird ventilator in surfactant treated immature baboons with RDS was associated with increased expiratory airway resistance and indices of impaired ventilation, but not oxygenation. Ventilator management in the NICU, especially weaning, may be affected by the specific ventilator in use.