Reflex control of inspiratory duration in newborn infants

1986 ◽  
Vol 60 (6) ◽  
pp. 2007-2014 ◽  
Author(s):  
P. C. Kosch ◽  
P. W. Davenport ◽  
J. A. Wozniak ◽  
A. R. Stark
Keyword(s):  
Newborn Infants ◽  
Face Mask ◽  
Curvilinear Relationship ◽  
Flow Volume ◽  
Healthy Infants ◽  
Switch Mechanism ◽  
Respiratory Valve ◽  
Reflex Control ◽  
Resistive Loads ◽  
Manifold System

We applied graded resistive and elastic loads and total airway occlusions to single inspirations in six full-term healthy infants on days 2–3 of life to investigate the effect on neural and mechanical inspiratory duration (TI). The infants breathed through a face mask and pneumotachograph, and flow, volume, airway pressure, and diaphragm electromyogram (EMG) were recorded. Loads were applied to the inspiratory outlet of a two-way respiratory valve using a manifold system. Application of all loads resulted in inspired volumes decreased from control (P less than 0.001), and changes were progressive with increasing loads. TI measured from the pattern of the diaphragm EMG (TIEMG) was prolonged from control by application of all elastic and resistive loads and by total airway occlusions, resulting in a single curvilinear relationship between inspired volume and TIEMG that was independent of inspired volume trajectory. In contrast, when TI was measured from the pattern of airflow, the effect of loading on the mechanical time constant of the respiratory system resulted in different inspired volume-TI relationships for elastic and resistive loads. Mechanical and neural inspired volume and duration of the following unloaded inspiration were unchanged from control values. These findings indicate that neural inspiratory timing in infants depends on magnitude of phasic volume change during inspiration. They are consistent with the hypothesis that termination of inspiration is accomplished by an “off-switch” mechanism and that inspired volume determines the level of vagally mediated inspiratory inhibition to trigger this mechanism.

Reflex control of expiratory duration in newborn infants

1985 ◽  
Vol 58 (2) ◽  
pp. 575-581 ◽  
Author(s):  
P. C. Kosch ◽  
P. W. Davenport ◽  
J. A. Wozniak ◽  
A. R. Stark
Keyword(s):  
Airway Pressure ◽  
Newborn Infants ◽  
Neural Mechanism ◽  
Face Mask ◽  
Emg Activity ◽  
Healthy Infants ◽  
Elastic Loading ◽  
Respiratory Valve ◽  
Lung Deflation ◽  
Manifold System

We investigated the effect on expiratory duration (TE) of application of graded resistive and elastic loads and total airway occlusions to single expirations in 9 full-term healthy infants studied on the 2nd or 3rd day of life. The infants breathed through a face mask and pneumotachograph, and flow, volume, airway pressure, and diaphragm electromyogram (EMG) were recorded. Loads were applied to the expiratory outlet of a two-way respiratory valve using a manifold system. Application of all loads resulted in expired volumes (VE) decreased from control (P less than 0.05), and changes were progressive with increasing loads. As VE became smaller, end-expiratory volume (EEV) became greater. TE, measured either from the pattern of airflow or airway pressure, or from diaphragm EMG activity, progressively increased with increasing loads and was greatest with total occlusions (P less than 0.05, compared with control). Resistive loading resulted in a greater accumulated VE history than elastic loading to the same EEV. For equivalent changes in EEV, TE was more prolonged with resistive than with elastic loading. Expiratory loading did not change the inspiratory duration determined from the diaphragm EMG activity of the breath immediately following each loaded expiration. These findings in infants are consistent with an integrative neural mechanism that modulates TE in response to the accumulated VE history, including both EEV and rate of lung deflation.

A VALVE FOR RESPIRATORY STUDIES IN INFANTS

PEDIATRICS ◽  
1961 ◽  
Vol 27 (4) ◽  
pp. 645-647
Author(s):  
Richard J. Golinko ◽  
Abraham M. Rudolph
Keyword(s):  
Dead Space ◽  
Newborn Infants ◽  
Dilution Effect ◽  
Face Mask ◽  
The Body ◽  
Large Head ◽  
The Face ◽  
Residual Capacity ◽  
Respiratory Valve ◽  
Body Plethysmograph

PULMONARY function studies in small infants have been limited in the past by failure to develop practical methods for collecting expired gas samples. Adaption of a respiratory valve suitable for use in small subjects with small tidal volumes has been difficult and has led to the use of techniques with the body plethysmograph, contour face mask and large head chamber. The body plethysmograph offers only indirect data and requires considerable prepration before each study. In addition, it has the disadvantage that once the infant is placed in the plethysmograph chamber further manipulations of the infant are not possible. Systems using the contour face mask on head chamber involve a large dead space which may be quite significant when one considers the small volumes dealt with. In order to overcome the problem of large dead space, Cayler et al., similar to others, circulated air across the face of the contour mask. However, because of the dilution effect, differences in the composition of the inspired and expired gases were very small and therefore the chance for error in the calculations was increased. Berglund and Karlberg, and Geubelle et al., while studying functional residual capacity in infants, found that practically all quiet, healthy newborn infants breathe through the nose and can also tolerate the insertion of small tubes in their nostrils for varying periods. On the basis of these observations, a respiratory valve has been designed for insertion directly into the nostrils, permitting collection of total expired air. The valve, especially adapted for use in small infants, offers minimal resistance to respiration and has a dead space of 0.8 ml.

Effect of changes in lung volume on respiratory system compliance in newborn infants

1989 ◽  
Vol 67 (3) ◽  
pp. 1192-1197 ◽  
Author(s):  
F. Ratjen ◽  
R. Zinman ◽  
A. R. Stark ◽  
L. E. Leszczynski ◽  
M. E. Wohl
Keyword(s):  
Tidal Volume ◽  
Respiratory System ◽  
Lung Volume ◽  
Newborn Infants ◽  
Face Mask ◽  
Flow Volume ◽  
Respiratory System Compliance ◽  
Tidal Breathing ◽  
Volume Changes ◽  
Passive Flow

Total respiratory system compliance (Crs) at volumes above the tidal volume (VT) was studied by use of the expiratory volume clamping (EVC) technique in 10 healthy sleeping unsedated newborn infants. Flow was measured with a pneumotachograph attached to a face mask and integrated to yield volume. Volume changes were confirmed by respiratory inductance plethysmography. Crs measured by EVC was compared with Crs during tidal breathing determined by the passive flow-volume (PFV) technique. Volume increases of approximately 75% VT were achieved with three to eight inspiratory efforts during expiratory occlusions. Crs above VT was consistently greater than during tidal breathing (P less than 0.0005). This increase in Crs likely reflects recruitment of lung units that are closed or atelectatic in the VT range. Within the VT range, Crs measured by PFV was compared with that obtained by the multiple-occlusion method (MO). PFV yielded greater values of Crs than MO (P less than 0.01). This may be due to braking of expiratory airflow after the release of an occlusion or nonlinearity of Crs. Thus both volume recruitment and airflow retardation may affect the measurement of Crs in unsedated newborn infants.

Transition from dynamically maintained to relaxed end-expiratory volume in human infants

1989 ◽  
Vol 67 (5) ◽  
pp. 2107-2111 ◽  
Author(s):  
A. A. Colin ◽  
M. E. Wohl ◽  
J. Mead ◽  
F. A. Ratjen ◽  
G. Glass ◽  
...  
Keyword(s):  
Chest Wall ◽  
Mechanical Characteristics ◽  
Newborn Infants ◽  
Respiratory Pattern ◽  
First Year ◽  
Flow Volume ◽  
Volume Changes ◽  
Human Infants ◽  
Healthy Infants ◽  
First Year Of Life

Newborn infants, in contrast to adults, dynamically maintain end-expiratory lung volume (EEV) above relaxation volume. The purpose of this study was to determine at what age children develop a breathing strategy that is relaxed, i.e., determined by the mechanical characteristics of the lung and chest wall. Forty studies were performed in 27 healthy infants and children aged 1 mo to 8 yr during natural sleep. Volume changes were recorded with the use of respiratory inductance plethysmography (RIP). The volume signal was differentiated to yield flow. Flow-volume representations were generated for a random sample of the recorded breaths to determine the predominant breathing strategy utilized, i.e., relaxed, interrupted, or indeterminate. The respiratory pattern was predominantly interrupted below 6 mo of age and predominantly relaxed over 1 yr of age. Mixed patterns were observed in children 6-12 mo of age. The number of breaths that could not be classified (indeterminate) decreased with age. Respiratory frequency measured from the sample of breaths decreased with age and was accompanied by an increase in expiratory time. We conclude that a relaxed EEV develops at the end of the first year of life and may be related to changes in the mechanical properties of the chest wall associated with growth as well as changes in respiratory timing.

Control of inspiratory duration in premature infants

1988 ◽  
Vol 64 (6) ◽  
pp. 2597-2604 ◽  
Author(s):  
R. E. Fox ◽  
P. C. Kosch ◽  
H. A. Feldman ◽  
A. R. Stark
Keyword(s):  
Premature Infants ◽  
Term Infants ◽  
Single Breath ◽  
Elastic Load ◽  
Resistive Loading ◽  
Elastic Loading ◽  
Measured Flow ◽  
Respiratory Valve ◽  
Reflex Control ◽  
Resistive Loads

We used single-breath mechanical loads and airway occlusions in premature infants to determine whether maturation influences the reflex control of inspiratory duration. We measured flow, volume, airway pressure, and surface diaphragmatic electromyogram (EMG) in 10 healthy preterm infants [33 +/- 1 (SD) wk gestation], 2–7 days of age. Three resistive and two elastic loads and occlusions were applied to the inspiratory outlet of a two-way respiratory valve. Application of all loads resulted in inspired volumes significantly decreased from control (P less than 0.001), and these decreases were progressive with increasing loads. Inspiratory duration (TI) was prolonged from control by all loads and occlusions when measured from the diaphragmatic EMG (neural TI) and by all but the smaller elastic load when measured from the flow tracing (mechanical TI). Similar decreases in inspired volume at the end of neural TI produced by application of both elastic and resistive loads resulted in comparable prolongation of neural TI. In contrast, for comparable volume decrements, resistive loading prolonged mechanical TI more than elastic loading (P less than 0.001). Mechanical and neural TI values of the breath after the loaded breath were unchanged from control values. Comparison of the neural volume-timing relationship in premature infants with our data in full-term infants suggests that the strength of the timing response to similar relative decrements in inspired volume is comparable. We conclude that reflex control of neural TI in premature infants depends on the magnitude of inspired volume and is independent of the volume trajectory.

Detection Latency of Added Loads to Breathing

1982 ◽  
Vol 63 (1) ◽  
pp. 11-15 ◽  
Author(s):  
J. G. W. Burdon ◽  
K. J. Killian ◽  
E. J. M. Campbell
Keyword(s):  
Peak Inspiratory Pressure ◽  
Normal Subjects ◽  
Reciprocal Relationship ◽  
Respiratory Cycle ◽  
Curvilinear Relationship ◽  
Similar Relationship ◽  
Detection Latency ◽  
Mechanical Information ◽  
Resistive Loads ◽  
Comparable Magnitude

1. Detection latency of a range of added elastic (0·95–4·50 kPa/l) and resistive (0·73–3·29 kPa l−1 s) loads to breathing were measured in five normal subjects. Detection latency was defined as the time from the onset of the breath to detection of the load. 2. Detection latency followed a curvilinear relationship when plotted as a function of the magnitude of the added loads. A similar relationship was found with both elastic and resistive loads although detection latencies to added elastances were longer than for added resistances. 3. When the added load was expressed in terms of comparable magnitude (peak inspiratory pressure) detection latencies for added elastances were found to be consistently longer than for added resistive loads. 4. These studies show that the detection latency to added inspiratory loads follows a reciprocal relationship, that detection latencies for elastic and resistive loads are clearly different and suggest that these loads are detected during the respiratory cycle at a time when the mechanical information regarding muscular pressure is greatest.

Renal Injury in Sick Newborn Infants: A Prospective Evaluation Using Urinary β2-Microglobulin Concentrations

PEDIATRICS ◽  
1988 ◽  
Vol 81 (3) ◽  
pp. 432-440
Author(s):  
Eric D. Tack ◽  
Jeffrey M. Perlman ◽  
Alan M. Robson ◽  
Cathy Hausel ◽  
Charles C. T. Chang
Keyword(s):  
Renal Injury ◽  
Confidence Limit ◽  
Newborn Infants ◽  
Tubular Injury ◽  
Creatinine Concentration ◽  
Term Infants ◽  
Urinary Creatinine ◽  
Β2 Microglobulin ◽  
Sick Newborn ◽  
Healthy Infants

Urinary concentrations of β2-microglobulin and creatinine were measured serially in 140 sick infants, of whom 109 were asphyxiated, and in 35 healthy preterm and term infants. First voided urines and samples from days 3 and 7 postpartum were studied. Urinary β2-microglobulin concentrations in healthy infants averaged 1.34 ± 1.34 mg/L (mean ± SD) in first voided specimens and 1.32 ± 0.98 mg/L in day 3 samples; the calculated upper limit of normal (95% confidence limit) was 4.00 mg/L. Elevated values (those exceeding the 95% confidence limit) occurred most often in the sick asphyxiated patients (56%); the first voided sample value in these patients was 10.0 ± 10.4 mg/L. The equivalent value in the sick nonasphyxiated infants was 8.32 ± 7.27 mg/L. Values were significantly and persistently elevated in the sick infants on days 3 and 7. Factoring β2-microglobulin levels by urinary creatinine concentration did not affect the significance of the findings. The increased urinary β2-microglobulin levels were not (1) related to gestational age; low β2-microglobulin values occurred at all gestational ages for both healthy and sick infants; (2) a consequence of urine flow rate; urinary β2-microglobulin did not correlate with urinary creatinine concentration or with urine to plasma creatinine ratio; and (3) a consequence of increased production of β2-microglobulin; urinary and serum β2-microglobulin values did not correlate (r = .03). Thus, we propose that the elevated levels of urinary β2-microglobulin in the sick infants were the consequence of tubular injury. This was associated with hematuria but not with a high incidence of azotemia or oliguria. In the most premature infants (<32 weeks), elevated urinary β2-microglobulin concentrations were associated with significantly increased urinary concentrations of sodium and potassium. These data suggest a higher prevalence of acute tubular injury in sick newborn infants than has been reported in previous studies in which more traditional indices of renal injury were used.

Effects of tactile stimulation on spontaneous breathing during face mask ventilation

2021 ◽  
pp. fetalneonatal-2021-322989
Author(s):  
Vincent D Gaertner ◽  
Christoph Martin Rüegger ◽  
Dirk Bassler ◽  
Eoin O'Currain ◽  
C Omar Farouk Kamlin ◽  
...  
Keyword(s):  
Surface Area ◽  
Tactile Stimulation ◽  
Randomised Trial ◽  
Secondary Analysis ◽  
Newborn Infants ◽  
Face Mask ◽  
Positive Pressure ◽  
Clinical Trial Registry ◽  
Term Infants ◽  
Prospective Randomised Trial

ObjectiveWe sought to determine the effect of stimulation during positive pressure ventilation (PPV) on the number of spontaneous breaths, exhaled tidal volume (VTe), mask leak and obstruction.DesignSecondary analysis of a prospective, randomised trial comparing two face masks.SettingSingle-centre delivery room study.PatientsNewborn infants ≥34 weeks’ gestation at birth.MethodsResuscitations were video recorded. Tactile stimulations during PPV were noted and the timing, duration and surface area of applied stimulus were recorded. Respiratory flow waveforms were evaluated to determine the number of spontaneous breaths, VTe, leak and obstruction. Variables were recorded throughout each tactile stimulation episode and compared with those recorded in the same time period immediately before stimulation.ResultsTwenty of 40 infants received tactile stimulation during PPV and we recorded 57 stimulations during PPV. During stimulation, the number of spontaneous breaths increased (median difference (IQR): 1 breath (0–3); padj<0.001) and VTe increased (0.5 mL/kg (−0.5 to 1.7), padj=0.028), whereas mask leak (0% (−20 to 1), padj=0.12) and percentage of obstructed inflations (0% (0–0), padj=0.14) did not change, compared with the period immediately prior to stimulation. Increased duration of stimulation (padj<0.001) and surface area of applied stimulus (padj=0.026) were associated with a larger increase in spontaneous breaths in response to tactile stimulation.ConclusionsTactile stimulation during PPV was associated with an increase in the number of spontaneous breaths compared with immediately before stimulation without a change in mask leak and obstruction. These data inform the discussion on continuing stimulation during PPV in term infants.Trial registration numberAustralian and New Zealand Clinical Trial Registry (ACTRN12616000768493).

Metabolic Fuel and Hormone Responses to Fasting in Newborn Infants

PEDIATRICS ◽  
1979 ◽  
Vol 64 (5) ◽  
pp. 613-619
Author(s):  
Charles A. Stanley ◽  
Endla K. Anday ◽  
Lester Baker ◽  
Maria Delivoria-Papadopolous
Keyword(s):  
Gestational Age ◽  
Plasma Glucose ◽  
Neonatal Period ◽  
Newborn Infants ◽  
Older Children ◽  
Glucose Levels ◽  
Metabolic Fuel ◽  
Healthy Infants ◽  
Lower Plasma Glucose ◽  
Appropriate For Gestational Age

To examine why newborn infants frequently cannot maintain adequate levels of plasma glucose in the interval between delivery and the time they are first fed, circulating metabolic fuel and regulatory hormone concentrations were determined in 44 healthy infants at the end of an eight-hour postnatal fast. Plasma glucose fell below 40 mg/100 ml prior to eight hours in four of 24 term-appropriate-for-gestational-age (AGA), two of nine preterm-AGA, five of six term-small-for-gestational-age (SGA), and three of five preterm-SGA infants. Fuel and hormone patterns in the premature and SGA infants were not different from those found in term-AGA infants. Results in these neonates differed in two areas from the response to fasting seen later in life. In fasted term-AGA infants, ketones were low (β-hydroxybutyrate 0.29 ± 0.04 mM/liter) despite elevated concentrations of fatty acid precursors (1.4 ± 0.07 mM/liter), and the group of infants studied failed to demonstrate the increase in plasma ketones with lower glucose levels (r = +.23, P = .07) which is found in older children. Levels of glucose precursors were two to three times higher in term-AGA infants (lactate 2.9 ± 0.2 mM/liter; alanine 0.48 ± 0.02 mM/liter) than levels found beyond the neonatal period and, in contrast to older children and adults, were not diminished in infants with lower plasma glucose (lactate, r = -.28, P = .035; alanine, r = -.33, P = .02). These differences between the responses to postnatal fasting and those seen beyond the neonatal period suggest that the capacity for both hepatic ketone synthesis and gluconeogenesis is not fully developed at birth.

Thyroarytenoid muscle activity during hypoxia in awake lambs

1990 ◽  
Vol 69 (6) ◽  
pp. 1998-2003 ◽  
Author(s):  
J. P. Praud ◽  
E. Canet ◽  
D. Dalle ◽  
A. Bairam ◽  
M. Bureau
Keyword(s):  
Lung Volume ◽  
Muscle Activity ◽  
Early Life ◽  
Face Mask ◽  
Flow Volume ◽  
Adductor Muscles ◽  
Thyroarytenoid Muscle

It is generally accepted that hypoxia in early life results in active laryngeal braking of expiratory airflow via the recruitment of glottic adductor muscles. We examined the electromyogram expiratory activity of the thyroarytenoid muscle in seven 11- to 18-day-old awake nonsedated lambs exposed to an inspired O2 fraction of 0.08 for 18 min. The lambs breathed through a face mask and a pneumotachograph. During baseline prehypoxic breathing, the thyroarytenoid muscle was largely inactive in each awake lamb. Unexpectedly, no recruitment of the thyroarytenoid muscle was recorded during hypoxia in any of the seven lambs; simultaneous examination of the flow-volume curves revealed an absence of expiratory airflow braking. Also unexpectedly, marked expiratory activity of the thyroarytenoid muscle was recorded, with each expiration occurring within less than 10 s after the return to room air. The resulting delay of expiration was apparent in the flow-volume loops. Thus, in awake 11- to 18-day-old lambs, 1) active expiratory glottic adduction is absent during hypoxia and 2) a return from hypoxia to room air results in prolonged expiration as well as active glottic adduction that controls end-expiratory lung volume.

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