Volume In Infants Research Articles

The open circuit nitrogen washout technique for measuring the lung volume in infants: methodological aspects

BACKGROUNDLung volume measurement by nitrogen washout is widely used in infants, though a lack of accuracy and changes of calibration over time have been reported. The potential sources of error...

3-D sonographic volume measurement of the cerebral ventricular system: in vitro validation

This in vitro study evaluates the accuracy and observer dependency of a freehand three-dimensional (3-D) ultrasound system for measuring cerebral ventricular volume in infants. A sphere, a cylinder, and three cerebral ventricle phantoms were made of agarose and embedded in an echogenic matrix after measuring true volumes by water displacement. Volumes of the models were calculated by 3-D software after manual contour marking on ultrasound cross-sections. Mean ± SD sonographic volume was 94.6% ± 7.3% ( n = 130) of true volumes. Intraobserver variation ( n = 10) was 2.3%–5.3% for complete investigation (scanning and marking), and 1.8%–4.1% for marking alone. Difference of means ( n = 10) between two observers was 7.6% to 10.8% for complete investigation, and 0.6% to 1.6% for the marking process. We conclude that 3-D freehand ultrasonography may be useful for examining ventricle dilatation in infancy.

Pathophysiology of changes in absolute lung volumes.

Changes in absolute lung volumes are common in lung disease and result in significant impacts on gas exchange, respiratory muscle function, the sensation of dyspnoea, and limitations to maximal exercise. Though our knowledge regarding the magnitude and determinants of changes in lung volumes in health and disease has increased in the past 20 years, a number of important questions remain unanswered. Consideration of the limitations of specific methods for measuring lung volumes is essential when analysing published studies regarding absolute lung volumes in infants, children and adults. Though functional residual capacity is most commonly measured in children and adults with the subject awake and at rest, increasingly attention is being directed to making these measurements under clinically more relevant conditions (e.g. during exercise, sleep, anesthesia, or mechanical ventilation). The relationships between dynamic changes in functional residual capacity, flow limitation during tidal breaths, sensation of dyspnoea and exercise limitation are important to understand, and are the focus of current and future research. Improved understanding of these relationships may lead to improvements in therapy of patients with acute and chronic lung disease and are likely to be particularly important for evaluating the efficacy of and optimal patient selection for new modes of therapy, such as lung volume reduction surgery.

Perioperative assessment of respiratory compliance and lung volume in infants with congenital diaphragmatic hernia: Prediction of outcome

Background/Purpose: Infants who have congenital diaphragmatic hernia (CDH) have high mortality and morbidity. The aim of this study was to determine the relative ability of the results of serial measurements of compliance of the respiratory system (CRS) and lung volume (functional residual capacity (FRC)) to predict poor outcome: death or oxygen dependency at 28 days. In addition, the authors wished to document the evolution of any lung function abnormalities during the perioperative period. Methods: Daily measurements of CRS and FRC were made in the first week of life and subsequently during week 2 in 16 infants who had a median gestational age of 38 weeks and birth weight of 3.2 kg. Results: Seven infants had a poor outcome: five died and two others remained oxygen dependent beyond 28 days. The infants who had a poor outcome were characterized on day 1 by a significantly lower CRS, but not FRC ( P < .05). In comparison with results from day 1, the median CRS of the infants overall had significantly improved only by week 2 ( P < .05), there was no such significant change in FRC with increasing postnatal age. At week 2, only the CRS results differed significantly between those infants who had and who did not have poor outcome ( P < .05). Conclusion: The results of serial measurements of CRS, rather than FRC are the more useful predictor of outcome in infants who have CDH.

Echocardiographic Determinants of Clinical Course in Infants With Critical and Severe Pulmonary Valve Stenosis

Objectives. The purposes of this study were to determine the growth pattern of the pulmonary valve (PV) annulus and right heart structures in patients with critical and severe pulmonary stenosis (PS) after balloon dilation, and to determine any morphometric or hemodynamic differences between cyanotic infants with critical PS and asymptomatic infants with severe PS that may account for their varied clinical presentations.Background. Growth of the PV annulus and right heart structures in patients with critical PS after balloon valvuloplasty has not clearly been defined. In addition, the anatomic and hemodynamic factors that determine whether an infant with severe PS will present with cyanosis or without symptoms are not well understood.Methods. Measurements of the PV annulus, tricuspid valve (TV) annulus and main, right and left pulmonary arteries were obtained from initial and follow-up echocardiograms, and Z values were calculated. Hemodynamic data and balloon pulmonary valvuloplasty techniques were reviewed. Right ventricular (RV) volumes were measured from angiograms.Results. Fourteen patients with critical PS (mean [±SD] age 0.21 ± 0.37 months) and 20 patients with severe PS (mean age 2.6 ± 2.9 months) were evaluated at presentation and at 32 ± 33 and 42 ± 32 months of follow-up, respectively. Balloon pulmonary valvuloplasty was successful in 64% of patients with critical PS and in 90% of patients with severe PS. The PV, TV and pulmonary arteries increased in size after balloon pulmonary valvuloplasty in both groups at a rate that paralleled or exceeded the rate of somatic growth. The initial TV diameter and RV volume were smaller in patients with critical PS than in those with severe PS (p < 0.05 and p < 0.0008, respectively).Conclusions. After balloon pulmonary valvuloplasty in infants with critical and severe PS, right heart structures increase in size at a rate that parallels or exceeds the rate of somatic growth. The primary morphometric differences between these groups are a smaller TV diameter and RV volume in infants with critical PS. This may contribute to increased right to left atrial shunting and account for the variations in clinical presentation.(J Am Coll Cardiol 1997;29:1095–101)© 1997 by the American College of Cardiology

Gastric fluid volume in infants for pyloromyotomy.

To quantify gastric fluid volumes in infants with pyloric stenosis presenting for pyloromyotomy and to demonstrate endoscopically the efficacy of blind aspiration for gastric fluid recovery. We hypothesized that previous diagnostic contrast studies, preoperative nasogastric suction, and fasting interval would not affect these volumes. Seventy-five infants scheduled for pyloromyotomy were given atropine before induction of anaesthesia. For those who had undergone preoperative nasogastric suction, the nasogastric tube was aspirated and removed. A 14 F multiorificed orogastric catheter was blindly passed to aspirate gastric fluid for measurement. Following tracheal intubation, 15/75 subjects underwent gastroscopy to measure residual gastric fluid. Gastric fluid volume removed by blind aspiration averaged 4.8 +/- 4.3 ml.kg-1 with 83% of patients having > 1.25 ml.kg-1. Although 14 of the 15 patients evaluated by endoscope had < or = 1 ml residual gastric fluid, one had 1.8 ml.kg-1. Recovery of total gastric fluid volume by blind aspiration averaged 96 +/- 7%. The large gastric fluid volumes were independent of a history of barium study, preoperative nasogastric suction, and fasting interval. Infants with pyloric stenosis have large gastric fluid volumes which are not substantially reduced by preoperative nasogastric suction. Blind aspiration of gastric contents prior to induction of anaesthesia provides a reliable estimate of total gastric fluid for most of these infants, although the occasional infant may retain a small amount of gastric fluid. The clinical importance of such a residual volume is uncertain.

Ultrasonographic assessment of intragastric volume in neonates: factors affecting the relationship between intragastric volume and antral cross-sectional area.

Measuring antral cross-sectional area by ultrasonography can be an ideal way to evaluate intragastric milk volume in infants. Technical details, however, remain to be established before its clinical application. We investigated the effects of posture and ultrasonographic plane on the correlation between milk volume and antral cross-sectional area. After gastric aspiration through a nasogastric tube, healthy newborns were fed 0, 10, 20, and 40 ml of milk cumulatively, and antral cross-sectional area was measured in either upright, sitting, or right lateral position. To determine the best sonographic plane, subjects were put in the right lateral position and antral cross-sectional area was measured in the plane of the aorta and either the superior mesenteric artery, the superior mesenteric vein, the midline of the abdominal surface, 1 cm right of midline, or 2 cm right of midline. The results showed that antral cross-sectional area reflects intragastric milk volume most accurately, with minimal gas interference when measured in the right lateral position. The area correlates well with milk volume in the plane of the aorta and either the superior mesenteric artery, the superior mesenteric vein, or the midline. Next, we studied the effect of intragastric gas on the antral cross-sectional area in subjects who were given 40 ml of milk followed by an injection of air. More than 20 ml of intragastric gas increases antral cross-sectional area significantly. Ultrasonographic evaluation of intragastric volume requires attention to the above factors.

Diamond-Blackfan Anemia Natural History and Sequelae of Treatment

To define further the natural history of treated Diamond-Blackfan anemia (DBA), a congenital anemia characterized by a paucity of erythroid precursors, we analyzed 76 patients diagnosed or followed at Children's Hospital, Boston, between 1931 and 1992. Although DBA is generally defined as macrocytic, we found that mean corpuscular volume in infants aged <5 months rarely exceeded the normal range and is of little diagnostic value. Macrocytosis in patients aged > or = 5 months was more striking. Nine of 16 patients who never received steroids experienced remissions, sometimes after years of transfusions. Thirty-one of 56 patients receiving corticosteroids responded. Of these 31, 13 experienced remissions, 11 remained steroid dependent and 7 later required transfusions. Most nonresponders maintained transfusion dependence. Patients frequently (64%) experienced treatment-related morbidity, most commonly hemosiderosis. The relative risk of leukemia was profoundly elevated (RR, 200; 95% CI, 54.5-512.1) and hematologic parameters at long-term follow-up were often abnormal. While potential responsiveness to steroids and relative ease of red cell transfusion make DBA one of the most treatable congenital marrow failure syndromes, both disease-related and treatment-related factors contributed to a limited prognosis (median survival, 38 years). Patients should be carefully monitored longitudinally for evidence of leukemia and adverse effects of therapy, and alternative treatment strategies should be considered on an individual basis.

Ventilatory depression by halothane in infants and children.

The purpose of this study was to extend previous observations of a greater decrease in tidal volume in infants than in children during halothane anaesthesia. We analyzed the inspiratory flow waveform recorded during spontaneous ventilation in: infants, two to six months of age, and children, one to five years of age. In addition we analyzed the CO2 signal and the pressure waveform during an occluded inspiration. The pressure generated during the initial 100 msec of inspiratory occlusion, an index of respiratory drive, was analyzed to give some insight into the aetiology of the age-related differences. In 15 infants and 15 children, Flow (V), pressure (Pao) and PCO2 were recorded at three concentrations of inspired halothane (FIH): 0%, 1% and 2% which correspond to an endtidal halothane concentration of about 0.3%, 0.9% and 1.3% respectively. Data were analyzed for minute ventilation (Vi) and parameters of timing (Total time (Ttot), Inspiratory time (Ti)), the amplitude of the neural output (mean inspiratory flow (VT/Ti), tidal volume (VT)) and the shape of the inspiratory breath profile (the inspiratory centroid flow (Ci/Ti), the inspiratory duty cycle (Ti/Ttot)). In some, the airway was occluded at end expiration and the slope of the initial 100 msec of occlusion (dP/dt) together with the maximal negative pressure (PMAX) were measured. Estimates of respiratory mechanics E'rs (PMAX/VT) and (VT/Ti)/(dP/dt) were obtained. The VT and Ttot decreased with increasing FIH in both infants and children (P < 0.05). The PETCO2 increased in both groups and the % increase was greater in infants.(ABSTRACT TRUNCATED AT 250 WORDS)

A new technique to generate and assess forced expiration from raised lung volume in infants.

We have developed a new technique that allows assessment of infant lung function over an extended volume range. The lungs are rapidly inflated to a predetermined inflation pressure (PP) using a modified diaphragm pump. Forced expiratory flow-volume (FEFV) curves are then generated from raised lung volumes using an inflatable plastic jacket. We studied 26 normal infants with a median age of 14 mo (range, 3 to 23 mo). FEFV curves were obtained in each infant from end-tidal inspiration and from lung volumes set by a range of PP (15 to 20 cm H2O). Mean (SE) volume above FRC was 107 ml (9 ml), and mean forced expiratory time was 0.73 s (0.05 s) at end-tidal inspiration. Both measurements increased progressively with increases in PP to 251 ml (13 ml) and 1.04 s (0.06 s), respectively, at 20 cm H2O PP (p < 0.0001). Mean intrasubject coefficient of variation was 15.5% (95% confidence interval, 12 to 19%) for maximal flow at FRC, but it was less than 6% (95% CI, 4 to 8%) for forced expiratory volume-time (FEVt) measurements at all levels of PP. Twenty-seven recurrently wheezy infants with a median age of 13 mo (range, 6 to 18 mo) were subsequently studied using a PP of 17.5 cm H2O. Wheezy infants had a lower VmaxFRC [mean (1.39 ml/s/cm) and 95% CI (1.15 to 1.63 ml/s/cm)] than did normal infants (1.78 ml/s/cm; CI, 1.51 to 2.05) (p < 0.05). FEV1 measurements were all lower in wheezy infants than in normals infants: mean FEV0.5, 1.86 ml/cm (CI, 1.73 to 1.98) and 2.31 ml/cm (CI, 2.15 to 2.48), respectively (p < 0.0001); FEV0.75, 2.20 ml/cm (CI, 2.07 to 2.32) and 2.72 ml/cm (CI, 2.52 to 2.91), respectively (p < 0.0001); FEV1.0, 2.42 ml/cm (CI, 2.26 to 2.58) and 2.84 ml/cm (CI, 2.63 to 3.06), respectively (p < 0.005). The Ci values of each FEVt measurement did not overlap between the wheezy and normal groups; however, the CI values of VmaxFRC overlapped markedly. In addition, FEVt parameters showed greater sensitivity in detecting reduced lung function (71 to 89%) than did VmaxFRC parameters (56%). We conclude that (1) FEVt measurements derived from a lung volume set by a standardized pressure are more reproducible than flow measurements in the tidal volume range; (2) FEVt measurements are significantly lower in wheezy infants than in normal infants, show less overlap than flow measurements in the tidal volume range, and therefore are better able to separate the two populations.

Lung volume measurements in wheezy infants: comparison of plethysmography and gas dilution

The accuracy both of plethysmographic measurements of thoracic gas volume (TGV) and determinations of functional residual capacity (FRC) by gas dilution techniques in infants with obstructive lung disease is subject to continued dispute. We studied 25 wheezy infants and compared TGV derived from end-expiratory airway occlusions (TGVEE), corrected TGV after end-inspiratory airway occlusions (TGVEI), and FRC determined by nitrogen wash-out (FRCN2). Group mean TGVEE and TGVEI differed significantly (25.8 +/- 8.4 versus 24.6 +/- 7.1 ml.kg-1). TGVEE and FRCN2 did not differ significantly. TGVEE and TGVEI, as well as TGVEE and FRCN2, and TGVEI and FRCN2 data, respectively, showed lack of agreement. Based on 95% confidence intervals, calculated from TGVEE data, 14 of the 25 infants showed a significantly higher TGVEI than TGVEE; only one patient had a significantly lower TGVEI. Compared to FRCN1 data, TGVEE and TGVEI measurements yielded lower values in at least one third of our patients. The present study illustrates, that there is no gold standard for the measurement of lung volume in infants with airway obstruction.

Improved detection of abnormal respiratory function using forced expiration from raised lung volume in infants with cystic fibrosis

The raised volume rapid thoracic compression (RVRTC) technique is a recently developed method of measuring lung function in infants. The measurements of forced expiratory volume-time (FEVt) parameters from raised lung volumes have been shown to be less variable than maximal flow at functional residual capacity (VmaxFRC), obtained from the conventional rapid thoracic compression (RTC) technique. Measurements of VmaxFRC are highly variable, and may not be sensitive enough to detect a difference between normal infants and infants with cystic fibrosis (CF). The aim of this study was to determine whether the raised volume rapid thoracic compression technique could detect abnormal lung function in a group of CF infants with no current respiratory symptoms. Twelve CF infants were studied (median age 10.5 months, range 3-18 months), and compared to normative data collected previously on 26 healthy infants (median age 14 months, range 3-23 months). We found that VmaxFRC failed to detect any difference between the two groups. CF infants had significantly smaller FEV0.5 and FEV0.75 measurements at a lung volume set by 17.5 cmH2O predetermined inflation pressure (PP) both as raw values and when expressed as percentage predicted. We conclude that the raised volume rapid thoracic compression technique is a sensitive tool, able to detect abnormal lung function in infants with cystic fibrosis. This abnormality was not demonstrated by measurements derived from the conventional rapid thoracic compression technique in the tidal volume range.

Magnetic Resonance Measurement of Volumes Using a Phantom

Cine magnetic resonance (MR) is an established method for determining cardiac ventricular volumes in adults. The reported section slice thickness may be too thick for accurate measurement of ventricular volumes in infants and young children. In this article, acceptable slice thickness is established for cine MR in children. Balloons filled with a dilute gadolinium solution were immersed in a water bath. The balloons were scanned using a fast scan technique to simulate cine MR. Scanning was performed using different slice thicknesses. Volumes were calculated using previously reported techniques. These calculated volumes were compared to direct measurement of the balloon volumes using graduated syringes. The balloons varied in volume from 0.9 mL to 27.3 mL. Measurements using 3- and 5-mm slice thickness sections were found to be significantly more accurate than 10-mm slice thickness sections. Section thickness should be less than 1-cm when performing cine MR in infants and small children for measurement of ventricular volumes.

Role of positive end-expiratory pressure changes on functional residual capacity in surfactant treated preterm infants.

Both surfactant replacement and positive end-expiratory pressure (PEEP) increase lung volume in infants with respiratory distress syndrome (RDS). We measured pulmonary mechanics and functional residual capacity (FRC) in 21 preterm infants with RDS, > 48 hr post-surfactant therapy (BW, 1,168 +/- 441 g; GA, 28.3 +/- 2.8 weeks; postnatal age, 3-7 days). A non-linear but significant increase in mean FRC was noted as PEEP increased from 2 to 5 cmH2O: 18.4 +/- 4.7 mL/kg at 2 cmH2O; 19.7 +/- 4.3 mL at 3 cmH2O; 22.6 +/- 5.5 ml/kg at 4 cmH2O; and 26.2 +/- 6.2 mL/kg at 5 cmH2O (P < 0.01). Because of the synergistic combined effect on lung volume, surfactant treated neonates should be weaned cautiously from PEEP during ventilatory management. Our study also suggests that the occurrence of inadvertent end-distending pressure during FRC measurement in the ventilated neonate lead to erroneous results.

Systolic blood pressure and blood volume in preterm infants.

Blood volume and systolic blood pressure (SBP) were measured in 43 preterm infants. Mean (SD) blood volume was 83 (19) ml/kg (range 48-119) and SBP 50 (9) mm Hg (range 34-69), showing a significant overall relationship. Blood volume in infants with SBP > 60 mm Hg (110 (6) ml/kg) was significantly higher than in infants with SBP 40-60 mm Hg (78 (16) ml/kg) and in infants with SBP < 40 mm Hg (75 (10) ml/kg). In conclusion, SBP is of limited value in detecting hypovolaemia in very low birthweight infants.

Nongeometric Doppler stroke volume determination is limited by aortic size

Noninvasive stroke volume determination by Doppler echocardiography has traditionally required estimation both of mean flow rate during ejection by Doppler methods and of flow area by cross-sectional or M-mode echocardiography. 1 Spodick and Koito 2 recently reported a method for estimating stroke volume from Doppler echocardiographic tracings alone, which they term non-geometric because no area measurement is used. Instead, mean left ventricular ejection rate is estimated from mean Doppler velocity and is then multiplied by Doppler ejection time to yield stroke volume. We reasoned that if there is a physiologic relation between ejection rate and Doppler velocity, truly independent of aortic size, the nongeometric method should also accurately estimate stroke volume in infants and children, who have a wide range of aortic size.

Gastric residual volume in infants and children following a 3-hour fast

The effect of a 3-hour versus a 10-hour preoperative f asting interval on the gastric residual volume and gastric pH o f pediatric patients was evaluated. Forty-four healthy infants, 1 month to 5 years of age, were randomly assigned to one of two groups. The 3-hour nil per os (NPO) group consisted of 19 infants kept NPO for 3 hours following ingestion of up to 4 ounces of 5% dextrose in water (D5W). The control group consisted of 25 infants who remained NPO an average of 10 hours prior to surgery. Gastric residual volume was calculated using the dye-dilution technique. After the dye marker was injected into the stomach, complete aspiration of the stomach (including the volume of dye marker plus residual gastric contents) was attempted as another method to measure gastric residual volume. There were no significant differences in gastric residual volume between the 3-hour and the 10-hour NPO groups using either the dye-dilution or aspiration methods. However, there were significant differences between the two measuring techniques. Gastric residual volume was significantly greater in volume when measured by the dyedilution technique than it was when measured by the aspiration technique in both the 10-hour ( p < 0.009) and the 3-hour ( p < 0.0009) NPO groups. Complete aspiration of a known volume of fluid injected through the orogastric tube was not possible in 23 of the 44 (52.4%) infants. Mean gastric pH was <2.0 in both groups. It is concluded that in healthy infants and children, a 3-hour NPO period following ingestion of clear liquids does not affect gastric residual volume or gastric pH compared to longer fasting intervals.

Estimation of lung volume in infants by echo planar imaging and total body plethysmography.

Echo planar imaging (an extremely fast method of magnetic resonance imaging) was used to measure lung volume in a group of nine infants, all of whom had had respiratory problems. The mean echo planar imaging estimate of total lung volume was 44 +/- 9 ml/kg. In each case the right lung was larger than the left (ratio 52.8:47.2%). The mean thoracic gas volume was 36 +/- 8 ml/kg. The entire sequence of images of the thorax (about 400) takes five minutes to complete, infants require no sedation, and there are no side effects.

Correlation of right ventricular volume using axial angulated ventriculography to known right ventricular cast volumes in infants and children with congenital heart disease

To calculate right ventricular (RV) volumes from biplane cineangiography obtained in nonstandard views, regression equations were developed from RV casts of known volume. Volumes were calculated using Simpson's rule from casts ranging from 2 to 42 ml from 25 postmortem specimens with various congenital heart diseases. The casts were divided into 2 groups: group 1 (n = 15) with abnormal or group 2 (n = 10) with normal RV hemodynamic measurements. Biplane cinegrams were taken in the anterolateral, anterior and long axis oblique, hepatoclavicular and sitting up projections. The true volume of each cast was determined from its weight and specific gravity. Excellent correlations were obtained between measured and true volumes (r = 0.92 to 0.96) in all projections, although each projection overestimated the true volume (slope value <1). The regression equations obtained from group 1 were not statistically different from those in group 2 in any view. Although the application of different regression equations is required in measuring RV volumes by multiple angulated angiography, these regression equations appear not to be affected by the hemodynamic state of the ventricle. These results are important in assessing RV volume in pediatric patients with congenital heart disease using axial angulated ventriculography.

A modified Pitot tube for the accurate measurement of tidal volume in children.

A device using modification of a Pitot tube has been designed for measurement of tidal volume in infants and small children. Its accuracy was compared both n vitro and n vivo to that of a calibrated pneumotachograph (Fleish #1) designed for a similar flow range. In vitro measurement of air flow with the modified Pitot tube (MPT) was within 5% of the pneumotachograph readings over a range of 1-60 l/min. Similar accuracy was found with measurement of tidal volumes from 20 ml to 1 l, delivered by a calibrated volume-cycled ventilator using a variety of inspiratory flow rates. Tidal volume measurements with the MPT were compared to the pneumotachograph using helium, oxygen, carbon dioxide, and a range of nitrous oxide/oxygen mixtures. A manual control was incorporated into the MPT electronics to allow direct measurements of tidal volume with different nitrous oxide/oxygen concentrations. In vivo, the insertion of the MPT into the patient circuit caused no apparent changes in ventilatory parameters in children under 20 kg. Measurement of tidal volumes with the MPT agreed to within 8% of pneumotachograph readings. The low dead space (1.5 cc) and light weight (12 gm) of the MPT confer advantages over the pneumotachograph (15 ml dead space and a weight of 90 gm) for routine use in pediatric anesthesia.