Effect of posture on oxygenation and respiratory muscle strength in convalescent infants

Patient positioning and its impact on perioperative outcomes in children: A narrative review

Patient positioning interacts with a number of body systems and can impact clinically important perioperative outcomes. In this educational review, we present the available evidence on the impact that patient positioning can have in the pediatric perioperative setting. A literature search was conducted using search terms that focused on pediatric perioperative outcomes prioritized by contemporary research in this area. Several key themes were identified: the effects of positioning on respiratory outcomes, cardiovascular outcomes, enteral function, patient and carer-centered outcomes, and soft issue injuries. We encountered considerable heterogeneity in research in this area. There may be a role for lateral positioning to reduce respiratory adverse outcomes, head elevation for intubation and improved oxygenation, and upright positioning to reduce peri-procedural anxiety.

Prone Position Minimizes the Exacerbation of Effort-dependent Lung Injury: Exploring the Mechanism in Pigs and Evaluating Injury in Rabbits

BACKGROUND

Vigorous spontaneous effort can potentially worsen lung injury. This study hypothesized that the prone position would diminish a maldistribution of lung stress and inflation after diaphragmatic contraction and reduce spontaneous effort, resulting in less lung injury.

METHODS

A severe acute respiratory distress syndrome model was established by depleting surfactant and injurious mechanical ventilation in 6 male pigs ("mechanism" protocol) and 12 male rabbits ("lung injury" protocol). In the mechanism protocol, regional inspiratory negative pleural pressure swing (intrabronchial balloon manometry) and the corresponding lung inflation (electrical impedance tomography) were measured with a combination of position (supine or prone) and positive end-expiratory pressure (high or low) matching the intensity of spontaneous effort. In the lung injury protocol, the intensities of spontaneous effort (esophageal manometry) and regional lung injury were compared in the supine position versus prone position.

RESULTS

The mechanism protocol (pigs) found that in the prone position, there was no ventral-to-dorsal gradient in negative pleural pressure swing after diaphragmatic contraction, irrespective of the positive end-expiratory pressure level (-10.3 ± 3.3 cm H2O vs. -11.7 ± 2.4 cm H2O at low positive end-expiratory pressure, P = 0.115; -10.4 ± 3.4 cm H2O vs. -10.8 ± 2.3 cm H2O at high positive end-expiratory pressure, P = 0.715), achieving homogeneous inflation. In the supine position, however, spontaneous effort during low positive end-expiratory pressure had the largest ventral-to-dorsal gradient in negative pleural pressure swing (-9.8 ± 2.9 cm H2O vs. -18.1 ± 4.0 cm H2O, P < 0.001), causing dorsal overdistension. Higher positive end-expiratory pressure in the supine position reduced a ventral-to-dorsal gradient in negative pleural pressure swing, but it remained (-9.9 ± 2.8 cm H2O vs. -13.3 ± 2.3 cm H2O, P < 0.001). The lung injury protocol (rabbits) found that in the prone position, spontaneous effort was milder and lung injury was less without regional difference (lung myeloperoxidase activity in ventral vs. dorsal lung, 74.0 ± 30.9 μm · min-1 · mg-1 protein vs. 61.0 ± 23.0 μm · min-1 · mg-1 protein, P = 0.951). In the supine position, stronger spontaneous effort increased dorsal lung injury (lung myeloperoxidase activity in ventral vs. dorsal lung, 67.5 ± 38.1 μm · min-1 · mg-1 protein vs. 167.7 ± 65.5 μm · min-1 · mg-1 protein, P = 0.003).

CONCLUSIONS

Prone position, independent of positive end-expiratory pressure levels, diminishes a maldistribution of lung stress and inflation imposed by spontaneous effort and mitigates spontaneous effort, resulting in less effort-dependent lung injury.

EDITOR’S PERSPECTIVE

Respiratory muscle function in the newborn: a narrative review

Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure-time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. IMPACT: Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.

Effect of prone and supine positioning on the diaphragmatic work of breathing in convalescent preterm infants

OBJECTIVES

To compare the work of breathing in the prone and supine positions in convalescent prematurely born infants.

WORKING HYPOTHESIS

The work of breathing would be lower in the prone compared to the supine position.

STUDY DESIGN

Prospective observational cohort study.

PATIENT-SUBJECT SELECTION

Consecutive preterm infants breathing unsupported in room air with a gestational age of 28-34 weeks in a tertiary neonatal intensive care unit were studied before discharge from neonatal care.

METHODOLOGY

The diaphragmatic pressure time product (PTPdi) was used to assess the work of breathing, calculated as the integration of transdiaphragmatic pressure over the inspiratory time. The PTPdi was measured in prone, supine, and supine with 45° head-up tilt (supine-tilt) positions.

RESULTS

The mean (SD) PTPdi was lower in the prone (259 [68] cm H₂ O*s/min) compared with the supine position (320 [78] cm H₂ O*s/min, p= .005). The mean (SD) PTPdi was lower in the supine-tilt position (262 [76] cm H₂ O*s/min) compared with the supine position (p = .032). The PTPdi was not different between the prone and supine-tilt positions (p = .600). The difference in PTPdi between prone and supine was not independently associated with gestational age (standardized coefficient = 0.262, adjusted p= .335), birth weight (standardized coefficient = -0.249, adjusted p= .394) or postmenstrual age at study (standardized coefficient = -0.025, adjusted p= .902).

CONCLUSIONS

In convalescent preterm neonates, the work of breathing may be lower in the prone and supine-tilt positions, compared with supine.

Aerosol drug delivery to spontaneously-breathing preterm neonates: lessons learned

Delivery of medications to preterm neonates receiving non-invasive ventilation (NIV) represents one of the most challenging scenarios for aerosol medicine. This challenge is highlighted by the undersized anatomy and the complex (patho)physiological characteristics of the lungs in such infants. Key physiological restraints include low lung volumes, low compliance, and irregular respiratory rates, which significantly reduce lung deposition. Such factors are inherent to premature birth and thus can be regarded to as the intrinsic factors that affect lung deposition. However, there are a number of extrinsic factors that also impact lung deposition: such factors include the choice of aerosol generator and its configuration within the ventilation circuit, the drug formulation, the aerosol particle size distribution, the choice of NIV type, and the patient interface between the delivery system and the patient. Together, these extrinsic factors provide an opportunity to optimize the lung deposition of therapeutic aerosols and, ultimately, the efficacy of the therapy.In this review, we first provide a comprehensive characterization of both the intrinsic and extrinsic factors affecting lung deposition in premature infants, followed by a revision of the clinical attempts to deliver therapeutic aerosols to premature neonates during NIV, which are almost exclusively related to the non-invasive delivery of surfactant aerosols. In this review, we provide clues to the interpretation of existing experimental and clinical data on neonatal aerosol delivery and we also describe a frame of measurable variables and available tools, including in vitro and in vivo models, that should be considered when developing a drug for inhalation in this important but under-served patient population.

The Effectiveness of Prone and Supine Nesting Positions on Changes of Oxygen Saturation and Weight in Premature Babies

Introduction: Stress experienced by the baby will affect the body’s function by increasing the body’s metabolism. Nesting is used to reduce stress in premature babies. Nesting can be done in a supine or prone position. Few studies have examined the effects of body position on body weight and oxygen saturation. The objective of the study was to determine the difference in oxygen saturation and weight change on the use of nesting in the prone and supine positions in premature babies.Methods: The research used a quasi-experimental design. The sample consisted of 30 premature babies, which was obtained using a consecutive sample technique. The independent variables were nesting positioning (supine and prone), and the dependent variables were oxygen saturation and body weight. The data of oxygen saturation and the baby’s weight were collected using pulse oximetry; the baby’s weight scale used observation sheets. The data was analysed using the t-test, Wilcoxon Sign Ranks Test, and Mann Whitney U Test.Results: The results showed that there was a difference in oxygen saturation before and after the use of nesting in the supine (p=0.001) and prone position (p=0.000). There was a weight difference before and after the use of nesting in both supine (p=0.000) and prone position (p=0.000). There was no difference in oxygen saturation value and infant weight, before or after, between the supine position and the prone position (p=0.18; p=0.9).Conclusion: The use of nesting in both positions (supine or prone) can increase oxygen saturation and infant weight. Researchers recommend the use of nesting with supine or prone positions routinely in premature babies.

Effect of low tidal volume with PEEP on respiratory function in infants undergoing one-lung ventilation

BACKGROUND

An increasing number of studies have shown that low tidal volume (TV) with positive end-expiratory pressure (PEEP) offers lung protection during one-lung ventilation (OLV). Considering the unique physiological characteristics of infants, we aimed to determine the feasibility and effect of low TV with PEEP in infants undergoing OLV during thoracoscopy.

PATIENTS AND METHODS

We randomized 60 infants to a conventional group (group I: TV, 8-10 ml/kg; RR, 23-45 bpm; PEEP, 0 cmH₂O) or a low TV with PEEP group (group II: TV, 5-7 ml/kg; RR, 23-45 bpm; PEEP, 4-6 cmH₂O). Arterial blood gas analyses were performed at four time points: 5 min of two-lung ventilation (TLV, T₀), and 20 min, 40 min, and 60 min of OLV (T₁, T₂, T₃); hemodynamic parameters (heart rate, mean blood pressure), temperature, as well as gas exchange (SpO₂ and P_ETCO₂) and ventilation parameters (FiO₂, PEEP, P_max) were recorded simultaneously. Lung compliance and shunt were also calculated.

RESULT

No significant difference was found between both groups at T₀. Compared with T₀, P_ETCO₂, P_max, PaCO₂, lactic acid, and intrapulmonary shunt volume (Qs/Qt) were increased while PaO₂ and respiratory system compliance (Cdyx) were decreased noticeably in both groups at T₁, T₂, and T₃. At T₁, T₂, and T₃, P_max and Qs/Qt were much lower while P_ETCO₂, PaCO₂, and Cdyx were higher in group II than in group I. There was no significant difference in lactic acid and PaO₂ measurements between the two groups at T₁, T₂, and T₃.

CONCLUSION

Low TV with PEEP could be an effective intraoperative ventilation strategy for infants undergoing OLV during video-assisted thoracoscopic surgery and may reduce the risk of lung injury. However, this strategy, as well as the influence of intraoperative hypercapnia on infants, needs further investigation.

Effect of time and body position on ventilation in premature infants

BACKGROUND

Infants with respiratory dysfunction undergo regular position changes to improve lung function however it is not known how often a position change should occur. This study measured changes in lung function occurring over time after repositioning in preterm infants.

METHODS

Changes in end-expiratory level (EEL) and ventilation distribution were measured 30 mins, 2 h, and 4 h after repositioning into either prone, quarter turn from prone, or supine using Electrical Impedance Tomography (EIT). Physiological measurements were also taken.

RESULTS

Sixty preterm infants were included in the study. Infants receiving respiratory support (mechanical ventilation or continuous positive airway pressure (CPAP)) had improved ventilation homogeneity after 2 h (P < 0.01), maintained at 4 h. Spontaneously breathing infants had improved homogeneity at 2 h (P < 0.01) and improved global EEL after 4 h (P < 0.01) whereas infants receiving CPAP demonstrated an improved global EEL at 2 h (P < 0.01).

CONCLUSION

Regional ventilation distribution is influenced by time independent of changes due to body position. Differences exist between infants on ventilatory support compared with those who are spontaneously breathing. Infants receiving ventilatory support have a physiological peak in lung function after 2 h which remains above baseline at 4 h. A change in body position facilitates an improvement in lung function in infants on ventilatory support.

Respiratory muscle strength in healthy infants and those with surgically correctable anomalies

Assessment of respiratory muscle strength provides important diagnostic and prognostic information. Normative data in healthy, term infants is, however, limited. Surgically correctable birth defects, congenital diaphragmatic hernia (CDH) and abdominal wall defects (AWD), commonly have impaired diaphragm function. The study aims were to obtain normative data for respiratory muscle strength in healthy, term born infants at birth and at 6 weeks postnatal age (PNA) and to investigate the influence of growth and maturation on inspiratory muscle strength in CDH/AWD infants. Maximal inspiratory (cPimax) and expiratory (cPemax) pressures during crying were measured at birth in 67 healthy, term born infants (mean (SD) gestational age (GA) 39.4 (1.7) weeks) and reassessed in 27 at 6 weeks PNA. cPimax and functional residual capacity (FRC) (22.3 (4.2) ml/kg) were also measured in 23 infants with AWD/CDH (mean (SD) GA 36.9 (2.1) weeks) and reassessed in 16 at median (range) 6.5 (1.5-15) months PNA. In healthy infants, mean (SD) cPimax was 88.8 (19.33) cmH2 O and cPemax 61.8 (13.5) cmH2 O at birth, increasing significantly at followup to 100.9 (15.2) cmH2 O (P < 0.05) and 82.6 (19.4) cmH2 O (P < 0.001) respectively. Mean (SD) cPimax was significantly lower (47.5 (22.4) cmH2 O, P < 0.0001) in AWD/CDH infants compared to healthy infants at birth but had increased significantly to 88.1 (27.6) cmH2 O (P < 0.0001) at followup which correlated significantly with increases in FRC (r(2)  = 0.33, P = 0.0263). Infants with AWD and CDH have significantly reduced inspiratory muscle strength compared to healthy term born infants but strength increases markedly in early life.

One lung ventilation strategies for infants and children undergoing video assisted thoracoscopic surgery

The advantages of video assisted thoracoscopic surgery (VATS) in children have led to its increased usage over the years. VATS, however, requires an efficient technique for one lung ventilation. Today, there is an increasing interest in developing the technique for lung isolation to meet the anatomic and physiologic variations in infants and children. This article aims to provide an updated and comprehensive review on one-lung ventilation strategies for infants and children undergoing VATS. Search of terms such as ‘One lung ventilation for infants and children’, ‘Video assisted thoracoscopic surgery for infants and children’, and ‘Physiologic changes during one lung ventilation for infants and children’ were used. The search mechanics and engines for this review included the following: Kandang Kerbau Hospital (KKH) eLibrary, PubMed, Ovid Medline, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews. During the search the author focused on significant current and pilot randomized control trials, case reports, review articles, and editorials. Critical decision making on what device to use based on the age, weight, and pathology of the patient; and how to use it for lung isolation are discussed in this article. Furthermore, additional information regarding the advantages, limitations, techniques of insertion and maintenance of each device for one lung ventilation in infants and children were the highlights in this article.

Standardizing umbilical catheter usage in preterm infants

BACKGROUND AND OBJECTIVE

Absence of guidelines on umbilical arterial catheter (UAC) and umbilical venous catheter (UVC) use and inability to predict the hospital course may sway the frontline staff to overuse umbilical catheters in preterm infants. Our objective was to evaluate the feasibility of implementing guidelines standardizing the use of umbilical catheters and its impact on the incidence of sepsis and resource use.

METHODS

All inborn infants delivered at <33 weeks' gestation and admitted to the NICU were included in this quality improvement study. The primary outcome was proportion of infants receiving umbilical catheters. Secondary outcomes were central venous catheter (CVC) use and central line-associated bloodstream infection (CLABSI).

RESULTS

The proportion of infants receiving UACs and UVCs was significantly lower in postintervention (sustainment) phase than in the preintervention phase (93 [42.3%] vs 52 [23.6%], P = .0001) and (137 [62.6%] vs 93 [42.3%], P = .0001), respectively. There was no corresponding increase in the proportion of infants receiving peripherally inserted central catheters (PICCs) or surgical CVCs (SCVCs) during the sustainment phase. There was a significant reduction in the proportion of infants receiving CVCs (UVC, PICC, and SCVC) in the sustainment phase. The incidence of CLABSI was similar in the preintervention and sustainment phases.

CONCLUSIONS

Implementation of guidelines standardizing the use of umbilical catheters in the NICU is feasible. Fewer infants were exposed to the risk of UVC or UAC, and fewer resources were used.

Sleeping position and responses to a carbon dioxide challenge in convalescent prematurely born infants studied post-term

OBJECTIVES

To test the hypothesis that the ventilatory response to a carbon dioxide (CO2) challenge would be lower in the prone compared to the supine position in prematurely born infants studied post-term. To determine whether there were postural-related differences in respiratory drive, respiratory muscle strength, thoracoabdominal synchrony and/or lung volume.

DESIGN

Prospective cohort study.

SETTING

Tertiary neonatal unit.

PATIENTS

Eighteen infants (median gestational age 31 (range 22-32) weeks) were studied at a median of 5 (range 2-11) weeks post-term.

INTERVENTIONS

The ventilatory responses to three added carbon dioxide (CO2) levels (0% baseline, 2% and 4%) were assessed in the prone and supine positions.

MAIN OUTCOME MEASURES

The airway pressure change after the first 100 ms of an occluded inspiration (P0.1) (respiratory drive) and the maximum inspiratory pressure during crying with an occluded airway (Pimax) (respiratory muscle strength) were measured. The P0.1/Pimax ratio at each CO2 level and slope of the P0.1/Pimax response were calculated.

RESULTS

The mean P0.1 (p<0.05) and P0.1/Pimax (p<0.05) were higher and the functional residual capacity (p=0.031) lower in the supine compared to the prone position. The mean P0.1 and P0.1/Pimax increased independently of position as the percentage CO2 increased (p<0.001). There was no tendency for the differences in P0.1 and P0.1/Pimax between the prone and supine position to vary by CO2 level.

CONCLUSIONS

Convalescent, prematurely born infants studied post-term have a reduced respiratory drive, but not a lower ventilatory response to a CO2 challenge, in the prone compared to the supine position.

Effect of body position on preterm newborns receiving continuous positive airway pressure

AIM

To evaluate the effect of body position on the cardiorespiratory indicators of preterm newborns receiving nasal continuous positive airway pressure (CPAP).

METHODS

Analytical, observational, prospective, cross-sectional, randomised crossover study was carried out on sixteen newborns that received nasal CPAP. The infants had a mean gestational age of 29.7 ± 2 weeks and birthweight of 1353 ± 280 g. Cardiorespiratory indicators (respiratory rate, heart rate and oxygen saturation) were evaluated in each infant in the supine, prone and right and left lateral decubitus positions at intervals of 10 min over a period of 60 min.

RESULTS

The cardiorespiratory indicators were similar and within the normal range in the four decubitus positions. There was no difference in respiratory or heart rate between body positions. Although they showed desirable values, oxygen saturation was significantly lower in left lateral decubitus (96.6 ± 1.7%) when compared to the supine (97.1 ± 1.3%) and prone positions (97.4 ± 1.1%) (p = 0.00) and was also significantly lower in right lateral decubitus (96.9 ± 1.4%) when compared to the prone position (p = 0.00).

CONCLUSION

We found no preferential decubitus position for preterm newborns receiving nasal CPAP, the supine position may be a choice, but the left and right lateral positions were less advantageous in terms of oxygen saturation.

Physical therapy intervention in the neonatal intensive care unit

This article presents the elements of the Intervention section of the Infant Care Path for Physical Therapy in the Neonatal Intensive Care Unit (NICU). The types of physical therapy interventions presented in this path are evidence-based and the suggested timing of these interventions is primarily based on practice knowledge from expert therapists, with supporting evidence cited. Physical therapy intervention in the NICU is infant-driven and focuses on providing family-centered care. In this context, interventions to facilitate a calm behavioral state and motor organization in the infant, address positioning and handling of the infant, and provide movement therapy are presented.

Respiratory muscle assessment in acute exacerbation of chronic obstructive pulmonary disease and its role as a potential biomarker

BACKGROUND

AECOPD is a life threatening condition for patients with chronic obstructive pulmonary disease (COPD) and lack of specific biomarker hinders effective management. Sputum, blood, breath and urinary biomarkers have all been investigated. We measured maximum respiratory pressure post exacerbation once the patient was compliant with the test and after 6 weeks, to assess any correlations.

METHODS AND RESULTS

The maximum pressures were measured using a closed circuit spirometer with a clean rubber mouthpiece properly placed with the patients lips sealed around it. Patients were properly instructed to exhale slowly and completely, then inspire with maximum possible effort and advised to keep it for nearly 1.5 s for maximum inspiratory pressure (MIP). For maximum expiratory pressures (MEP) patients were instructed to inspire slowly and completely, then expire forcefully with maximum effort. With the recorded values TTI (time tension index) was calculated. This was repeated again after 6 weeks. Using Pearsons correlation coefficient we found that MIP had a negative correlation with TTI and a positive correlation with FEV1. FEV1 had a positive correlation with FVC. MEP showed no significant correlation with TTI, but a positive correlation with FEV1.

CONCLUSION

Acute exacerbations of COPD has a profound effect on the respiratory musculature especially the expiratory muscles but the maximum pressures are not specific enough to be prognostic markers. It might be worthwhile studying transformations of the respiratory musculature at the molecular level. More studies must be conducted to find a specific marker to aid in the management of the condition.

Benefícios do decúbito ventral associado ao CPAP em recém-nascidos prematuros

O objetivo deste estudo foi avaliar os benefícios nas variáveis clínicas do decúbito ventral (DV) associado a pressão positiva contínua nas vias aéreas (CPAP), em recém-nascido pré-termo (RNPT). Foi feito um estudo transversal em RNPT com utilização do CPAP internados na unidade de terapia intensiva (UTI). As frequências cardíaca (FC) e respiratória (FR), SpO2, quantificação do desconforto respiratório pelo boletim de Silverman e Andersen (BSA: quanto maior o valor, pior o desconforto respiratório) foram avaliados em cinco fases. Na fase I foram avaliadas a FC, FR, SpO2 e BSA em decúbito supino. Nas fases II, III, IV e V foram coletadas as mesmas variáveis da fase I após 5, 15, 30 e 60 min, respectivamente. O RNPT foi posicionado em DV logo após a fase I. Foi realizada análise de variância repetida para comparação entre todas as variáveis estudadas nas cinco fases, e utilizado-se teste de Bonferroni para análise post hoc. Foi considerada significância estatística quando p<0,05. No estudo, foram incluídos 13 RNPT, com média idade gestacional 33±1,5 semanas, sendo 7 do gênero masculino. Não houve alteração significante na FC, FR e SpO2, entre todas as fases. Houve redução no BSA nas fases III e IV quando comparadas à fase I: fase 1, 4,6±1,6 vs. fase III, 2,4±0,5 (p=0,02); fase I, 4,6±1,6 vs. fase IV, 2,4±0,5 (p=0,002). Concluiu-se, então, então que DV reduz o desconforto respiratório em RNPT quando associado ao CPAP, quando permanecem por, pelo menos, 15 min, sem alteração na FC, FR e SpO2.

Influência da posição prona na oxigenação, frequência respiratória e na força muscular nos recém-nascidos pré-termo em desmame da ventilação mecânica

OBJETIVO: Verificar a influência do posicionamento do recém-nascido prematuro sobre a força da musculatura respiratória, oxigenação e frequência respiratória. MÉTODOS: Estudo transversal com amostra pareada de recém-nascidos com idade gestacional inferior a 34 semanas, intubados, em processo final de desmame de ventilação mecânica. Foram excluídos aqueles com malformações, síndromes genéticas, doenças neuromusculares, traqueostomizados e em pós-operatório de cirurgias abdominais ou torácicas. As medidas de pressão inspiratória máxima foram aferidas utilizando-se manovacuômetro digital; a frequência respiratória através da observação das incursões respiratórias das crianças em um minuto e a saturação de oxigênio por oxímetro, nas posturas prona e supino. Os testes estatísticos aplicados foram Kruskal-Wallis, o teste t de Student e o coeficiente de correlação de Pearson, sendo significante p<0,05. RESULTADOS: Foram estudadas 45 crianças com síndrome do desconforto respiratório. A idade gestacional média foi de 30,4 semanas e o peso médio ao nascer de 1522g. Os valores de saturação de oxigênio foram mais elevados (p<0,001) e os de pressão inspiratória máxima mais baixos (p<0,001) na posição prona. Os valores de frequência respiratória foram semelhantes nas duas posições estudadas (p=0,072). CONCLUSÕES: Observaram-se menores valores de pressão inspiratória além de aumento da saturação de oxigênio na posição prona quando comparada à supino. Em relação à frequência respiratória, não foi observada variação entre as posturas prona e supino.

Effect of position on oxygen saturation and requirement in convalescent preterm infants

AIMS

To document the effect of position on oxygen saturation and changes in oxygen requirement in convalescent preterm infants.

METHODS

Twelve infants born ≥24 and ≤32 weeks gestation, extubated and without congenital anomaly were studied using nap polysomnography in prone and supine, twice weekly until discharge. Mean oxygen saturation (SpO(2)), minimum SpO(2) , mean minimum SpO(2) and time with SpO(2) < 90% were measured in active sleep.

RESULTS

Eight male and four female infants [median gestation 28 (24-31) weeks and median birthweight 1059 (715-1840) g] had 39 studies. For 21 of 39 studies, the infant was on respiratory support. Four infants had chronic lung disease (CLD). SpO(2) varied with postmenstrual age (PMA) (p = 0.003) but not with position (p = 0.36), and PMA did not influence the effect of position on SpO(2) (p = 0.19). SpO(2) was lower for those with CLD (p < 0.0001) and those on respiratory support (p < 0.001), but there was no effect of position (p = 0.97 and p = 0.67, respectively). From 36 weeks PMA, a change to supine did not increase oxygen requirement.

CONCLUSION

In preterm infants, PMA and residual respiratory disease have greater effects on oxygenation than position. A supine sleep position is not disadvantageous for preterm infants at discharge.

Ventilatory response to added dead space and position in preterm infants at high risk age for SIDS

OBJECTIVE

The vulnerability of prematurely born infants to sudden infant death syndrome (SIDS) in the prone position might be explained by a reduced ability to respond to a stress, such as hypercarbia, in that position; our objective, therefore, was to further explore the influence of position on the response to a stress.

WORKING HYPOTHESIS

The ability of prematurely born infants to respond to added dead space in the prone compared to the supine position would be impaired at the high risk age for SIDS.

PATIENTS

Twenty infants, median gestational age of 30 (range 24-32) weeks were studied at a median postmenstrual age (PMA) of 45 weeks. In addition, comparisons were made to the results of 25 infants studied at 36 weeks PMA.

METHODOLOGY

Infants were studied supine and prone. Breath by breath minute volume was measured at baseline and after a dead space was incorporated into the breathing circuit; the time constant of the response was calculated. The pressure generated in the first 100 msec of an occlusion (P0.1 ), the maximum inspiratory pressure during an airway occlusion and functional residual capacity (FRC) were also measured in both positions.

RESULTS

The median time constant was longer (38 (range 15-85) vs. 26 (range 2-40) sec (P = 0.002)). P0.1 lower (P = 0.003) and FRC higher (P = 0.031) in the prone compared to the supine position. In the prone position, the time constant correlated with PMA (P = 0.047), that is, the rate of response to added dead space was significantly damped with increasing postnatal age up to the critical age for SIDS.

CONCLUSIONS

The dampened rate of response to added dead space in the prone compared to the supine position lends support to the hypothesis that a poorer response to a stress may contribute to prematurely born infants increased risk of SIDS in the prone position.

Position and ventilatory response to added dead space in prematurely born infants

OBJECTIVES

Prematurely born infants are at increased risk of sudden infant death syndrome (SIDS) if slept prone.

WORKING HYPOTHESIS

Prematurely born infants would have an impaired response to an added dead space and lower respiratory muscle strength in the prone compared to the supine position.

STUDY DESIGN

Prospective study. PATIENT-SUBJECT SELECTION: Twenty-five infants, median gestational age of 30 (range 26-32) weeks.

METHODOLOGY

The infants were studied supine and prone at a median of 36 weeks postmenstrual age. Breath by breath minute volume was measured at baseline and after a dead space was incorporated into the breathing circuit; the time constant of the response was calculated. The maximum inspiratory occlusion pressure generated (MIOP) and the pressure generated over the first 100 msec (P(0.1)) during airway occlusion were assessed.

RESULTS

The median time constant was longer (26 (range 8-106) sec vs. 22 (range 6-92) sec (P = 0.045)) and the median MIOP (P = 0.001) and P(0.1) (P = 0.003) were lower in the prone compared to the supine position.

CONCLUSION

Prematurely born infants have a dampened response to tube breathing and reduced respiratory muscle strength in the prone compared to the supine position, which may contribute to their increased vulnerability to SIDS in the prone position.

Positioning of Preterm Infants for Optimal Physiological Development: a systematic review

EXECUTIVE SUMMARY

Positioning of preterm infants is a basic task of neonatal nursing care. A variety of outcomes are affected by different body positioning of preterm infants. This review evaluates the clinical evidence of the effects of positioning of preterm infants with regard to physiological outcomes and sleep states.

OBJECTIVES

To conduct a systematic review to determine the best available evidence related to the positioning of preterm infants. The specific review questions addressed were: the physiological outcomes affected by different positioning, and the best position for promoting sleep.

CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW

This review considered all studies that included infants born before 37 weeks of gestational age in any hospital setting. Outcomes included measures for physiologic effects and sleep state. The review primarily considered any randomized clinical trails (RCTs) that explored different positions in preterm infant but also included quasi-experimental designs.

SEARCH STRATEGY FOR IDENTIFICATION OF STUDIES

The search sought to find published and unpublished studies. The database search included: Pubmed, CINAHL, ProQuest, EMBASE, Science Direct, and Dissertation Abstracts International. Studies were additionally identified from reference lists of all studies retrieved.

ASSESSMENT AND DATA EXTRACTION

All studies were checked for methodological quality by two reviewers and data was extracted using tools developed by the Joanna Briggs Institute.

DATA ANALYSIS

The study results were pooled in statistical meta-analysis using Review Manager Software and summarized in narrative form where statistical pooling was not appropriate or possible.

RESULTS

Thirty two studies were included in the review. The results of this review support the prone position in preterm infants for improvement of arterial oxygen saturation, improved lung and chest wall synchrony of respiratory improvements, decreased incidence of apnea in infants with a clinical history of apnea, promoted sleep, and decreased gastroesophageal reflux. However, the prone position increased postural abnormalities, orthopaedic abnormalities of the feet, and delayed developmental musculature. The combined use of a postural support roll and a postural nappy while very preterm infants are nursed, improved hip and shoulder posture up to term postmenstrual age. The change in body position from horizontal to head-up tilt in very immature and unstable infants may affect the cerebral homodynamic. The management of position per se may not be sufficient for assisting preterm neonates to cope with the painful procedure. Furthermore, preterm infants are susceptible to oxygen desaturation in car seats and carrying slings.

CONCLUSION

Prone positioning was shown to have many advantages for prematurely born infants. But the longer, deep sleep period and fewer awakenings associated with a prone position would support higher vulnerability for preterm infants to sudden infant death syndrome (SIDS). Therefore, all preterm infants placed in the prone position should have continuous cardio-respiratory and oxygen saturation monitoring. Preterm infants should be placed in a properly supported position to ensure functional support of all parts of the body as well as ensuring physical safety. In addition, preterm infants should not be left unattended in car safety seats and carrying slings.

The effect of positioning on infant cries: implications for sudden infant death syndrome

OBJECTIVE

A definitive cause for sudden infant death syndrome (SIDS) has not yet been identified, but some theories point to laryngeal or respiratory causes, in addition to theories of reduced arousal or reduced autonomic response. The occurrence of SIDS has dropped since the movement to place newborns to sleep in the supine position; however, some research has found a respiratory disadvantage for infants in this position. The current paper studied acoustic characteristics of infant pain cries to determine the potential differences related to prone versus supine positioning.

METHODS

Fifty-one newborn infant cries were recorded during and following a blood draw screening procedure, with infants placed either in the supine or prone position. All infants were healthy, full-term infants. Complete crying episodes were audio-recorded, and results were based on compositional analysis and long-time average spectrum analysis across each crying episode.

RESULTS

Spectral analysis revealed acoustic differences related to infant positioning, and acoustic analysis also revealed that there were no respiratory differences between supine-positioned and prone-positioned infants. Overall, the acoustic differences suggest decreased arousal and/or a decreased response to pain for healthy infants recorded in the prone position.

CONCLUSIONS

As decreased arousal and prone positioning have been seen as possible causative factors for SIDS, the current results are seen as a successful step in evaluating the possibility of using acoustic analysis of infant cries as a means of evaluating SIDS risk for healthy infants.

Prone versus supine positioning in the well preterm infant: effects on work of breathing and breathing patterns

Premature infants with respiratory distress oxygenate better and have improved breathing synchrony when they are nursed in the prone position. We investigated whether work of breathing (WOB) is decreased in the prone position in healthy premature infants nearing discharge from the neonatal intensive care unit. Nineteen convalescing premature infants in room air were studied in both supine and prone position. Positioning order was randomized. Mean birth weight was 1358 +/- 332 (SD) g, gestational age 29.7 +/- 2.1 weeks, weight at study 1757 +/- 248 g, and age at study 33.6 +/- 1.4 days. Calibrated respiratory inductance plethysmography (RIP) was used to measure tidal volume; an esophageal catheter estimated pleural pressure. Inspiratory, elastic, and resistive WOB were calculated and were unaffected by prone versus supine positioning (P = 0.46, 0.36, and 0.87, respectively). Similarly, respiratory rate, tidal volume, minute ventilation, and lung compliance did not differ between positions. These data suggest that sleep position recommendations for healthy premature infants discharged home without oxygen should be no different than for term infants.

Effect of posture on respiratory function and drive in preterm infants prior to discharge

Our objective was to determine the effect of posture on respiratory function and drive in prematurely born infants immediately prior to discharge. Twenty infants (6 oxygen-dependent), median gestational age 29 weeks (range, 25-32), were studied at a median postconceptional age (PCA) of 36 weeks (range, 33-39). On 2 successive days, infants were studied both supine and prone; each posture was maintained for 3 hr. The order on each day in which postures were studied was randomized between infants. At the end of each 3-hr period, tidal volume (Vt), inspiratory (Ti) and expiratory (Te) time, respiratory rate, and minute ventilation were measured. In addition, respiratory drive was assessed by measuring the pressure generated in the first 100 msec of an imposed airway occlusion (P(0.1)), and respiratory muscle strength was assessed by recording the maximum inspiratory pressure (Pimax) generated against an occlusion which was maintained for at least five breaths. Overall, tidal volume was higher (P < 0.05), but respiratory rate (P < 0.05), P(0.1) (P < 0.05), and Pimax (P < 0.05) were lower in the prone compared to the supine position. There were no significant differences in Ti or Te between the two postures. In oxygen-dependent infants only, minute volume was higher in the prone position (P < 0.05). In conclusion, posture-related differences in respiratory function are present in prematurely born infants studied prior to neonatal unit discharge.

Effect of posture on oxygenation, lung volume, and respiratory mechanics in premature infants studied before discharge

OBJECTIVES

To determine if the prone versus the supine posture was associated with higher oxygenation levels in prematurely born infants before discharge, whether any such effect was explained by alterations in lung volume or respiratory mechanics, and if the changes were greater in oxygen-dependent infants.

PATIENTS

Twenty infants (10 oxygen-dependent), median gestational age 30 (range: 27-32) weeks, were studied at a median postconceptional age of 35 weeks (range: 32-38 weeks).

METHODS

On 2 successive days, infants were studied both supine and prone; each posture was maintained for 3 hours. Oxygen saturation was continuously monitored and at the end of each 3-hour period; compliance and resistance of the respiratory system and functional residual capacity (FRC) were measured.

RESULTS

Overall, the median oxygen saturation and FRC were significantly higher in the prone position; compliance of the respiratory system and resistance of the respiratory system were not significantly affected by posture. Differences in oxygen saturation and FRC were significantly higher in the prone posture in the oxygen-dependent, but not the nonoxygen-dependent infants.

CONCLUSIONS

Superior oxygenation in the prone posture in oxygen-dependent premature infants studied before discharge could be explained by higher lung volumes.