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.     

Measurement of breath amplitudes: Comparison of three noninvasive respiratory monitors to integrated pneumotachograph

Measurement of breath amplitude (BA) and similarly tidal volume (V_T) in newborn infants is the standard for detection of apnea and hypopneas. The purpose of our study was to compare the accuracy for BA by three frequently utilized noninvasive respiratory monitors: respiratory inductive plethysmography (RIP), mercury in silastic strain gauges (SG), and impedance pneumography (IP). Twenty healthy full-term infants were studied in both supine and prone postures. The RC and AB gain factors for RIP were obtained using qualitative diagnostic calibration (QDC) procedure. The electrical gain of IP was set equivalent to the BA signal of a pneumotachograph (PNT). The three devices were calibrated in the supine posture and measurements were repeated in the prone posture without changing their calibration factors. Compared to PNT, postural change did not significantly alter BA measured by RIP. The accuracy of breath-to-breath BA measurement in the prone posture was worse for IP and SG compared to RIP and PNT. In contrast to SG or IP, the accuracy of BA measurement maintained was by RIP after a postural change from supine to prone in fullterm newborns. Pediatr Pulmonol. 1993; 16:254–258. © 1993 Wiley-Liss, Inc.     

Effect of positioning on pulmonary function of newborns: Comparison of supine and prone position

The effect of positioning on pulmonary function has been previously evaluated, and the prone position has been reported to be preferable for neonates with various respiratory diseases. Studies in healthy neonates have yielded conflicting results. Using a crying pulmonary function test, we examined the effect of positioning on pulmonary function in healthy full-term neonates. Thirty-nine infants with a mean birthweight (± SD) of 3,140 ± 379 g and a mean gestational age (± SD) of 39.8 ± 1.6 weeks were investigated during the first 6 hours of life. Measurements were obtained in both supine and prone positions using a computerized volume-flow system. There were statistically significant decreases in crying vital capacity (CVC) and peak expiratory flow rate (PEF) in the prone compared with the supine position. However, there were no significant differences in forced expiratory flow rate at 75% (V₇₅), 50% (V₅₀), and 25% (V₂₅) of vital capacity between the two positions. These results suggest that prone positioning decreases lung volume and increases resistance of upper airways. We conclude that healthy neonates should be in the supine posture for optimal ventilation. Pediatr Pulmonol. 1996; 21:167–170. © 1996 Wiley-Liss, Inc.     

Interaction between chest wall motion and lung mechanics in normal infants and infants with bronchopulmonary dysplasia.

Asynchronous or paradoxic motion between the rib cage and abdomen may be seen in infants with lung disease. We have recently shown that after bronchodilator administration, the degree of asynchrony decreases proportionately to the improvement in lung mechanics. However, whether such thoraco-abdominal asynchrony (TAA) is a useful indicator of lung function in a cross-sectional population, i.e., whether asynchrony correlates with baseline lung mechanics, is unknown. Therefore, we quantitated the degree of TAA using respiratory inductive plethysmography during quiet sleep in ten infants with bronchopulmonary dysplasia (BPD) and six weight-matched control infants. We displayed abdominal wall (AB) and rib cage (RC) motion on an X-Y recorder, and from the tidal breathing loop we calculated a phase angle phi, between 0 degrees and 180 degrees as an index of asynchrony (synchronous RC/AB motion = 0 degrees, paradox = 180 degrees). Lung resistance (RL) and compliance/kg (CL/kg) were calculated from esophageal and mouth pressure, tidal volume, and tidal flow. As expected, BPD infants had abnormally high RL, and low CL/kg when compared to controls. All infants with BPD displayed marked thoraco-abdominal asynchrony (phi = 102 +/- 16 degrees, mean +/- SEM; range 35 degrees-160 degrees) with controls displayed synchronous chest wall motion (phi = 8 +/- 3 degrees, range 0 degrees-15 degrees) (P less than 0.001). The degree of TAA was significantly correlated with RL (r = 0.773, P less than 0.001) and inversely correlated with CL/kg (r = -0.67, P less than 0.01). We conclude that in infants of similar weight, TAA may be used as a cross-sectional index reflecting both resistive and elastic properties of the lungs.     

A critical assessment of uncalibrated respiratory inductance plethysmography (Respitrace®) for the measurement of tidal breathing parameters in newborns and infants

We have compared results obtained with an uncalibrated respiratory inductance plethysmograph (RIP) with those of a face mask and pneumotachograph (PNT) for the computerized measurement of the time to reach peak tidal expiratory flow as a ratio of total expiratory time (t_pTEF:t_E). Simultaneous measurements were made in 32 healthy neonates aged 0–3 weeks, 35 healthy infants aged 5–82 weeks, and 28 infants aged 15–94 weeks with physician diagnosed recurrent wheeze. The group mean (±SD) values of t_pTEF:t_E determined using a PNT were 0.455 (±0.129), 0.263 (±0.077), and 0.232 (±0.089) for the neonates, healthy infants and infants with recurrent wheeze respectively. RIP gave mean (±SD) values that were 0.055 (±0.044) and 0.025 (±0.104) lower than the PNT in healthy neonates and infants with recurrent wheeze respectively; RIP values were 0.002 (±0.073) higher in the healthy infants over 4 weeks of age than measurements by PNT. Although the difference between the two measurements was not related to the thoracoabdominal phase angle, as measured from Lissajous figures, examination of the RIP ribcage and abdominal signals revealed that many healthy subjects, while appearing clinically in phase, had ribcage and abdominal signals that differed markedly from each other in terms of convexity/concavity during early expiration. This may explain the lack of agreement between the two methods. We conclude that uncalibrated RIP should be used with caution for the determination of t_pTEF:t_E, even in subjects whose ribcage and abdomen appear to move synchronously. The measurement of t_pTEF:t_E did not differentiate between the healthy infants and infants with recurrent wheezing. Pediatr Pulmonol. 1995; 20:119–124 . © 1995 Wiley-Liss, Inc.     

Cardiorespiratory measurements during field tests in CF: Use of an ambulatory monitoring system

Respiratory inductive plethysmography (e.g., LifeShirt) may offer in‐depth study of the cardiorespiratory responses during field exercise tests. The aims of this study were to assess the reliability, discriminate validity, and responsiveness of cardiorespiratory measurements recorded by the LifeShirt during field exercise tests in adults with CF. To assess reliability and discriminate validity, participants with CF and stable lung disease and healthy participants performed the 6‐Minute Walk Test (6MWT) and Modified Shuttle Test (MST) on two occasions. To assess responsiveness, participants with CF experiencing an exacerbation performed the 6MWT at the start and end of an admission for intravenous antibiotics. The LifeShirt was worn during all exercise tests. Reliability and discriminate validity were assessed in 18 participants with CF (mean (SD) age: 26 (10) years; FEV₁ %predicted: 69.2 (23)%) and 18 healthy participants (age: 24 (5) years, FEV₁ %predicted: 92 (8)%). There was no difference in 6MWT and MST performance between days and reliability of cardiorespiratory measures was acceptable (bias: P > 0.05; CV < 10%). Participants with CF demonstrated a significantly greater response to exercise (e.g., ventilation, respiratory rate) compared to healthy participants indicating discriminate validity. Responsiveness was assessed in 12 participants with CF: clinical measurements and 6MWT performance improved (61 (81) min; P < 0.05) however, cardiorespiratory measurements recorded by the LifeShirt remained the same (bias: P > 0.05; CV < 10%). This study provides evidence that cardiorespiratory responses can be measured non‐invasively during field exercise tests in adults with CF. Reliability and discriminate validity of key cardiorespiratory measurements recorded by the LifeShirt were demonstrated. Some information on responsiveness is reported. Pediatr Pulmonol. 2011; 46:253–260. © 2011 Wiley‐Liss, Inc.     

Electromagnetic inductance plethysmography to measure tidal breathing in preterm and term infants

Tidal breathing measurements which provide a non‐invasive measure of lung function in preterm and term infants are particularly useful to guide respiratory support. We used a new technique of electromagnetic inductance plethysmography (EIP) to measure tidal breathing in infants between 32 and 42 weeks postconceptional age (PCA). Tidal breathing was measured in 49 healthy spontaneously breathing infants between 32 and 42 weeks PCA. The weight‐corrected tidal volume (V_T) and minute volume (MV) decreased with advancing PCA (V_T 6.5 ± 1.5 ml/kg and MV 0.44 ± 0.04 L/kg/min at 32–33 weeks, respectively; 6.3 ± 0.9 ml/kg and 0.38 ± 0.02 L/kg/min at 34–36 weeks; and 5.1 ± 1.1 ml/kg and 0.28 ± 0.02 L/kg/min at term, V_T P < 0.001 and MV P < 0.01 for 32–33 weeks PCA vs. term; V_T P = 0.016 and MV P = 0.015 for 34–36 weeks PCA vs. term). Respiratory frequency and the phase angle decreased significantly with advancing PCA but the flow parameter t_PTEF/t_E did not change significantly. Using a new technique to measure tidal breathing parameters in newborn infants, our data confirms its usability in clinical practice and establishes normative data which can guide future respiratory management of newborn infants. Pediatr Pulmonol. 2013; 48:160–167. © 2012 Wiley Periodicals, Inc.     

Diaphragmatic flutter in three babies with bronchopulmonary dysplasia and respiratory syncytial virus bronchiolitis

Abnormalities of respiratory control, especially apnea, have been reported previously in infants with respiratory syncytial virus (RSV) infections. This is the first report of yet another abnormality of respiratory control, diaphragmatic flutter (DF), in infants with RSV infection. The presentation of these infants did not differ from the usual clinical presentation of RSV infection. While being monitored with respiratory inductive plethysmography for occurrences of apnea known to be common in RSV infection, DF was detected. This abnormality consisted of high frequency, diaphragmatic contractions which were intermittent in nature. They lasted no more than 4 days and were not associated with change in arterial oxygen saturation or heart rate. These infants were discharged free of DF and no further episodes have been observed over a 12-month period. © 1995 Wiley-Liss, Inc.     

Occlusion maneuver to detect the relative contribution of the rib cage and abdomen to tidal volume using respiratory inductive plethysmography in infants

Respiratory inductive plethysmography (RIP) records movements of the rib cage (RC) and abdomen (AB). A calibration procedure is needed to determine their relative contribution to tidal volume. We evaluated the hypothesis that the relative contribution of the RC and AB could be defined from respiratory efforts made during a brief occlusion of the airways in 10 infants aged 6.5–19 months, who were studied in quiet sleep. Six occlusions were performed during tidal breathing, with and without a pneumotachograph (PNT) and face mask in place. We analyzed the periods of occluded respiratory effort when RC and AB were in opposite directions (paradoxical movements), plotting RC vs. AB and performing a least-squares linear regression to estimate the ratio of the coefficients of AB/RC. Multiple linear regression of AB and RC over tidal volume during about 100 seconds of tidal breathing provided a reference standard. A ratio of 1 means that AB and RC make equal contributions to tidal volume. The feasibility of the occlusion maneuver was poor; only 51% of occlusions with PNT and 54% without led to a paradoxical movement with a good fit (r > 0.9). The mean coefficient of variation (range) was 9.35% (3.9–15.3%) with PNT and 12.1% (2.5%–26.3%) without it. The accuracy was very poor, with the mean AB/RC value being 0.94 with occlusions and 2.39 with multiple linear regression. The mean difference was 1.45 (SD 0.80), yielding 95% confidence limits for the difference of 0.12–3.01. We concluded that, due to its very poor accuracy and feasibility, the occlusion technique is not a useful method to calibrate RIP in infancy. Pediatr Pulmonol. 1996; 21:132–137. © 1996 Wiley-Liss, Inc.     

Work of breathing and respiratory drive in obesity

Obesity, particularly severe central obesity, affects respiratory physiology both at rest and during exercise. Reductions in expiratory reserve volume, functional residual capacity, respiratory system compliance and impaired respiratory system mechanics produce a restrictive ventilatory defect. Low functional residual capacity and reductions in expiratory reserve volume increase the risk of expiratory flow limitation and airway closure during quiet breathing. Consequently, obesity may cause expiratory flow limitation and the development of intrinsic positive end expiratory pressure, especially in the supine position. This increases the work of breathing by imposing a threshold load on the respiratory muscles leading to dyspnoea. Marked reductions in expiratory reserve volume may lead to ventilation distribution abnormalities, with closure of airways in the dependent zones of the lungs, inducing ventilation perfusion mismatch and gas exchange abnormalities. Obesity may also impair upper airway mechanical function and neuromuscular strength, and increase oxygen consumption, which in turn, increase the work of breathing and impair ventilatory drive. The combination of ventilatory impairment, excess CO(2) production and reduced ventilatory drive predisposes obese individuals to obesity hypoventilation syndrome.     

俯卧位通气的呼吸力学变化趋势

俯卧位通气作为 ARDS 的治疗手段之一,已被证明可以改善氧合、减轻呼吸机相关性肺损伤、提高患者生存率,其中的机制包括俯卧位时呼吸力学的改善。通过对俯卧位通气时呼吸系统的顺应性、胸腹腔压力、肺应力应变、流速、阻力、呼吸功等呼吸力学方面的变化趋势分析发现,对于重度 ARDS患者,俯卧位通气能获得对患者有益的呼吸力学变化,但俯卧位通气的时机等问题仍需进一步探讨。     

腹式呼吸对血压及呼吸性窦性心律不齐的影响

目的 :研究腹式呼吸对血压及呼吸性窦性心律不齐 （RSA）的影响。方法 :采用反馈型腹式呼吸训练仪 ,分析2 5例正常人腹式呼吸训练前后血压及呼吸性窦性心律不齐 （RSA）的动态变化。结果 :腹式呼吸训练 10min ,2 0min后RSA比静息状态显著减少 （ms,4 7± 13vs 36± 10 ,P <0 .0 1;4 8± 16vs 36± 10 ,P <0 .0 1） ,RSA在停止训练后较训练时降低 ,但较训练前显著减少 （ms,4 1± 16vs 36± 10 ,P <0 .0 1） ;训练 10min、2 0min后血压显著下降 ,收缩压更为明显 （kPa,14 .5± 1.5vs 14 .9± 1.3,P <0 .0 5 ;14 .5± 1.2vs 14 .9± 1.3,P <0 .0 5 ） ,舒张压无明显变化。结论 :腹式呼吸能降低血压、增强心副交感神经的兴奋性。     

Synchronized nasal intermittent positive pressure ventilation (SNIPPV) decreases work of breathing (WOB) in premature infants with respiratory distress syndrome (RDS) compared to nasal continuous positive airway pressure (NCPAP)

Synchronized nasal intermittent positive pressure ventilation (SNIPPV) is non-invasive respiratory support that delivers ventilator breaths via the nasal prongs. We hypothesized that SNIPPV is more effective than nasal continuous positive airway pressure (NCPAP) in premature neonates due to decreased work of breathing (WOB). Fifteen infants (BW: 1,367 +/- 325 g, GA: 29.5 +/- 2.4 weeks) were studied on (a) NCPAP at 5 cmH(2)O (NCPAP5) and (b) three increasing SNIPPV settings achieved by NCPAP5 with additional delivered peak inspiratory pressures (PIP) of 10, 12, and 14 cmH(2)O. Tidal volumes and transpulmonary pressures were estimated via calibrated respiratory inductance plethysmography (RIP) and esophageal pressures, respectively. Inspiratory (WOB(insp)), resistive (RWOB), and elastic (WOB(E)) components of WOB were calculated using standard methods. Compared to NCPAP5, (a) WOB(insp) and RWOB were significantly lower with SNIPPV12, and were similarly lower with SNIPPV14 and (b) WOB(E) was significantly lower only with SNIPPV14. WOB components did not differ significantly for the three SNIPPV settings. Tidal volume, respiratory rate (RR), minute ventilation, compliance, and phase angle were similar for all four measurements. In conclusion, compared to NCPAP, the addition of ventilator-delivered PIP during SNIPPV decreases WOB in premature infants.     

Diagnostic accuracy of the rapid shallow breathing index to predict a successful spontaneous breathing trial outcome in mechanically ventilated patients with chronic obstructive pulmonary disease

Objective

To evaluate the diagnostic accuracy of 2 threshold values (105 breaths per minute [bpm]/L and 130 bpm/L) of the rapid shallow breathing index (RSBI) to predict a successful weaning trial outcome in a homogenous group of patients with chronic obstructive pulmonary disease (COPD).

Methods

A consecutive population of patients with COPD who were intubated for hypercapnic respiratory failure during a 2-year period were studied prospectively. RSBI was measured by 2 investigators at minute 5 of the T-piece trial, whereas 2 other physicians evaluated the 30 minute T-piece trial as successful or unsuccessful, according to clinical criteria.

Results

Of 64 patients with COPD (53 male, 11 female) who constituted the study population, 42 patients (35 male, 7 female; aged 70 ± 9.2 years) completed the spontaneous breathing trial (SBT) and remained clinically stable (group 1). The remaining 22 patients (18 male, 4 female; aged 71.9 ± 4.7 years) had to return to ventilatory support by the end of the SBT because of clinical deterioration (group 2). The 2 threshold values that were evaluated had low specificity (38.1% for < 105 bpm/L and 66.7% for < 130 bpm/L), low sensitivity (63.6% for < 105 bpm/L and 54.5% for < 130 bpm/L), and low diagnostic accuracy (46.8% for < 105 bpm/L and 65.6% for < 130 bpm/L) in predicting a successful T-piece trial outcome.

Conclusion

RSBI measured early during an SBT cannot accurately predict the successful outcome of a T-piece trial in a homogenous population of patients with COPD.     

Apnea and periodic breathing in normal full-term infants during the first twelve months

The pediatric pneumogram is a frequently used tool in the diagnosis and management of apnea during infancy. We analyzed 287 pneumographic recordings from 123 full-term infants (63 males) obtained during the first 12 months of life to establish normative values for apnea, periodic breathing, and bradycardia. The results of the analysis were compared by sex and age. The number of infants who exhibited periodic breathing decreased significantly over time (78% at 0-2 weeks vs 29% at 39-52 weeks; P less than 0.05). However, for those infants who did breathe periodically, the percent of sleep time spent in this breathing pattern did not change with age. No apnea greater than or equal to 15 seconds was recorded in any infant, and apnea density (total apnea greater than or equal to 10 seconds in minutes/100 minutes sleep time) did not change with age or sex. Using our definitions, no bradycardia was identified. Normal full-term infants occasionally have apnea of 10, 11, or 12 seconds, and, until 6 months of age, the majority will have a small amount of periodic breathing (less than 1% of sleep time) during sleep at home.     

ARDS患者仰卧位通气与俯卧位通气的对比

目的通过ARDS患者仰卧位通气与俯卧位通气血流动力学指标和血气指标,探讨俯卧位通气在ARDS肺保护作用。方法对19例ARDS患者按机械通气时体位分两组,仰卧位通气组（11例）和俯卧位通气组（8例）,分别检测机械通气开始时（0h时）、2h时、24h时的血流动力学及血气的改变。结果两组对改善血流动力学方面作用不大,两组间MBP、CVP差异无明显性（P〉0．05）,而俯卧位通气对HR的改善在24h时较明显,与仰卧位通气比较差异有显著性（P〈0．05）。仰卧位通气与俯卧位通气均能较好改善PO2、PaO2／FiO2,俯卧位通气与仰卧位通气比较能更好的改善PO2、PaO2／FiO2,在24h时最明显。差异有显著性（P〈0．05）;两组对PCO2改善不显著。结论俯卧位通气较仰卧位通气能明显改善ARDS患者的氧合,对血流动力学改变不明显。俯卧位通气可能通过改善通气／血流比例失调来促进ARDS患者氧合,纠正缺氧。     

Effect of nasal CPAP on thoracoabdominal motion in neonates with respiratory insufficiency.

Thoracoabdominal motion (TAM) profiles were determined in ten infants requiring nasal continuous positive airway pressure (CPAP) and supplemental oxygen, in order to assess the influence of CPAP on chest wall function in infants with respiratory insufficiency. (TAM) was quantitated by respiratory inductive plethysmography, measuring relative motion of the rib cage and abdomen. Baseline pulmonary function (without CPAP support) was assessed from simultaneous measurements of transpulmonary pressure, air flow, and tidal volume. Measurements of (TAM) were acquired at baseline and at nasal CPAP levels of 0, 3, 5, and 8 cm H2O, in randomized order. Without CPAP, relative paradoxical motion occurred, i.e., the rib cage collapsed inward instead of expanding outward early in inspiration. With CPAP, TAM resembled the pattern in preterm infants, without lung disease. We found that nasal CPAP lowers the phase angle in infants with respiratory insufficiency (P less than 0.003), indicating improved synchrony of TAM. In addition, the improvement with nasal CPAP was related to the severity of pulmonary compromise at baseline. We speculate that changes in TAM associated with nasal CPAP arise from an interaction between pulmonary mechanics and an enhanced stability of the chest wall. In this context, the greater synchrony of TAM is suggestive of an improved breathing strategy. This may be a noninvasively obtainable marker of an effective nasal CPAP level in infants with altered pulmonary and chest wall mechanics.     

Effects of pursed-lip breathing and forward trunk lean postures on total and compartmental lung volumes and ventilation in patients with mild to moderate chronic obstructive pulmonary disease: An observational study

This study identified the effects of pursed-lip breathing (PLB), forward trunk lean posture (FTLP), and combined PLB and FTLP on total and compartmental lung volumes, and ventilation in patients with chronic obstructive pulmonary disease (COPD). Sixteen patients with mild to moderate COPD performed 2 breathing patterns of quiet breathing (QB) and PLB during FTLP and upright posture (UP). The total and compartmental lung volumes and ventilation of these 4 tasks (QB-UP, PLB-UP, QB-FTLP, PLB-FTLP) were evaluated using optoelectronic plethysmography. Two-way repeated measures ANOVA was used to identify the effect of PLB, FTLP, and combined strategies on total and compartmental lung volumes and ventilation. End-expiratory lung volume of ribcage compartment was significantly lower in PLB-UP than QB-UP and those with FTLP (P < .05). End-inspiratory lung volume (EILV) and end-inspiratory lung volume of ribcage compartment were significantly greater during PLB-FTLP and PLB-UP than those of QB (P < .05). PLB significantly and positively changed end-expiratory lung volume of abdominal compartment (EELV_AB ) end-expiratory lung volume, EILV_AB, tidal volume of pulmonary ribcage, tidal volume of abdomen, and ventilation than QB (P < .05). UP significantly increased tidal volume of pulmonary ribcage, tidal volume of abdomen, and ventilation and decreased EELV_AB, end-expiratory lung volume, and EILV_AB than FTLP (P < .05). In conclusion, combined PLB with UP or FTLP demonstrates a positive change in total and compartmental lung volumes in patients with mild to moderate COPD.