Optimal Conventional Mechanical Ventilation in Full-Term Newborns: A Systematic Review

Comparison of Assist/Control Ventilation with and without Volume Guarantee in Term or Near-Term Infants

OBJECTIVES

 This study aimed to compare the effects of volume guarantee (VG) combined with assist/control (AC) ventilation to AC alone on hypocarbia episodes and extubation success in infants born at or near term.

METHODS

 In this prospective cohort study, infants >34 weeks of gestation at birth, who were born in our hospital supported by synchronized, time-cycled, pressure limited, assist/control ventilation (AC) or assist-controlled VG mechanical ventilation (AC + VG) were included. After admission, infants received either AC or VG + AC using by Leoni Plus ventilator. The ventilation mode was left to the clinician. In the AC group, peak airway pressure was set clinically. In the VG + AC group, desired tidal volume was set at 5 mL/kg, with the ventilator adjusting peak inspiratory pressure to deliver this volume. The study was completed once the patient extubated.

RESULTS

 There were 35 patients in each group. Incidence of hypocarbia was lower in the VG + AC compared with AC (%17.1 and 22.8%, respectively) but statistically not significant. Out-of-range partial pressure of carbon dioxide (PCO2) levels were lower in the VG + AC group and it reached borderline statistical significance (p = 0.06). The median extubation time was 70 (42-110) hours in the VG + AC group, 89.5 (48.5-115.5) hours in the AC group, and it did not differ between groups (p = 0.47).

CONCLUSION

 We found combining AC and VG ventilation compared with AC ventilation alone yielded similar hypocarbia episodes and extubation time for infants of >34 gestational weeks with borderline significance lower out-of-range PCO2 incidence.

KEY POINTS

· Underlying lung pathology requiring mechanical ventilation support in term infant is heterogeneous.. · VG ventilation compared with conventional modes yielded similar hypocarbia episodes in term infants.. · Combining VG ventilation lead to borderline significance lower out-of-range PCO2 incidence..

Comparing ventilation modes by electrical impedance segmentography in ventilated children

Electrical impedance segmentography offers a new radiation-free possibility of continuous bedside ventilation monitoring. The aim of this study was to evaluate the efficacy and reproducibility of this bedside tool by comparing synchronized intermittent mandatory ventilation (SIMV) with neurally adjusted ventilatory assist (NAVA) in critically-ill children. In this prospective randomized case-control crossover trial in a pediatric intensive care unit of a tertiary center, including eight mechanically-ventilated children, four sequences of two different ventilation modes were consecutively applied. All children were randomized into two groups; starting on NAVA or SIMV. During ventilation, electric impedance segmentography measurements were recorded. The relative difference of vertical impedance between both ventilatory modes was measured (median 0.52, IQR 0-0.87). These differences in left apical lung segments were present during the first (median 0.58, IQR 0-0.89, p = 0.04) and second crossover (median 0.50, IQR 0-0.88, p = 0.05) as well as across total impedance (0.52 IQR 0-0.87; p = 0.002). During NAVA children showed a shift of impedance towards caudal lung segments, compared to SIMV. Electrical impedance segmentography enables dynamic monitoring of transthoracic impedance. The immediate benefit of personalized ventilatory strategies can be seen when using this simple-to-apply bedside tool for measuring lung impedance.

The effect of high-frequency oscillatory ventilator combined with pulmonary surfactant in the treatment of neonatal respiratory distress syndrome

OBJECTIVE

To investigate the efficacy of high-frequency oscillatory ventilation (HFOV) combined with pulmonary surfactant (PS) in the treatment of neonatal respiratory distress syndrome (NRDS).

METHODS

This study is a retrospective clinical study. Seventy-two NRDS neonates were selected as the subjects from November 2019 to November 2020, and divided into observation group (40 cases, HFOV treatment) and control group (32 cases, conventional mechanical ventilation treatment). All cases were treated with PS and comprehensive treatment. The therapeutic effect, arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2), Percentage of inhaled oxygen concentration (FiO2), mean arterialpressure, oxygenation index (OI), and complications were compared in the 2 groups.

RESULTS

The total effective rate of the observation group was 90.0%, significantly higher than that of the control group. After treatment, the observation group has higher PaO2 levels and lower levels of PaCO2, mean arterial pressure, FiO2, and OI than the control group. There was no significant difference in the incidence of complications between the 2 groups.

CONCLUSION

HFOV combined with PS has a significant effect on NRDS, which can improve the arterial blood gas index without increasing the incidence of complications.

Why we should care about full-term infants admitted to a neonatal intensive care unit

ABSTRACT This study aims to analyze why we should care about full-term newborns admitted to a neonatal intensive care unit. This is a documented, descriptive, and retrospective study of 262 full-term newborns. Variables used: newborns’ characteristics; main diagnosis, length of stay, follow-up by a multidisciplinary team; post-discharge referral. Most newborns were boys (52%), had a 5-minute Apgar score of nine, and most newborns and their mothers were white (61.1% and 48.9% respectively). Respiratory dysfunction was the main diagnosis (28.8%). Length of stay was eight days. There was a significant difference regarding length of stay (p=0.013), in which those with cardiorespiratory and other diseases stayed less time compared to those with malformation or maternal diseases. The social service was the most sought (81.2%) service, whereas physical therapy the least sought (18%). Newborns with higher weight were hospitalized for less time. Those that underwent physical therapy had longer stay (p<0.001). Main outcome was hospital discharge (68.7%) and referrals to the Basic Health Unit (57%). This study outcomes indicated newborns with less severe conditions, low number of specific studies for the full-term population, other diagnoses that refer to non-intensive care.

Por que devemos nos preocupar com os bebês a termo internados em uma unidade de terapia intensiva neonatal

RESUMO O objetivo deste estudo foi analisar a razão pela qual devemos nos preocuparmos com os bebês a termo internados em uma unidade de terapia intensiva neonatal. Trata-se de estudo documental, descritivo e retrospectivo de 262 recém-nascidos (RNs) a termo. As variáveis utilizadas foram: características dos RN; diagnóstico principal, tempo de permanência e acompanhamento pela equipe multiprofissional; e encaminhamento pós-alta. Houve prevalência do sexo masculino (52%), de Apgar 9 no 5º minuto e da raça/cor branca do RN e da mãe (61,1% e 48,9%, respectivamente). O diagnóstico principal foi a disfunção respiratória (28,8%), e o tempo de permanência foi de oito dias. Houve diferença significativa entre os tempos de permanência (p=0,013), em que as doenças cardiorrespiratórias e outras doenças levaram a um menor tempo de internação em relação à má formação ou às doenças maternas. O serviço social foi o mais procurado para o acompanhamento (81,2%) e a fisioterapia, o menos buscado (18%). RNs com maior peso ficaram menos tempo internados, e os acompanhados por fisioterapia apresentaram tempo de permanência mais elevados (p<0,001). O principal desfecho foi a alta hospitalar (68,7%) e encaminhamentos para a Unidade Básica de Saúde (57%). Os achados deste estudo apontam a presença de bebês menos graves, baixo número de estudos específicos para a população a termo e outros diagnósticos que nos remetem a cuidados não intensivos.

Numerical analysis of mechanical ventilation using high concentration medical gas mixtures in newborns

When administered in relatively high concentrations the mechanical properties of inhaled gas can become significantly different from air. This fact has implications in mechanical ventilation where adequate respiration and injury to the lungs or respiratory muscles can worsen morbidity and mortality. Here we use an engineering pressure loss model to analyze the administration of medical gas mixtures in newborns. The model is used to determine the pressure distribution along the gas flow path. Numerical experiments comparing medical gas mixtures with helium, nitrous oxide, argon, xenon, and medical air as a control, with and without an endotracheal tube obstruction were performed. The engineering pressure loss model was incorporated into a model of mechanical ventilation during pressure control mode, a ventilator mode that is often used for neonates. Results are presented in the form of Rohrer equations relating pressure loss to flow rate for each gas mixture with and without obstruction. These equations were incorporated into a model for mechanical ventilation resulting in pressure, flow rate, and volume curves for the inhalation-exhalation cycle. In terms of accuracy, published values of airway resistance range from 50 to 150 cmH₂O/L per second for a normal 3 kg infant. With air, the current results are 55 to 80 cmH₂O/L per second for 0.3 to 5 L/min. It is shown that density through inertial pressure losses has a greater influence on airway resistance than viscosity in spite of relatively low flow rates and small airway dimensions of newborns. The results indicate that the high-density xenon mixture can be problematic during mechanical ventilation. On the other hand, low density heliox (a mixture of helium and oxygen) provides a wider margin of safety for mechanical ventilation than the other gas mixtures. The argon or nitrous oxide mixtures considered are only slightly different from air in terms of mechanical ventilation performance.