Technique In Infants Research Articles

Experience with Advanced Endosurgical Procedures in Neonates and Infants

This report reviews the results of advanced endosurgical procedures in neonates and infants weighing less than 5 kg. Over a 2½-year period, 106 patients underwent 111 laparoscopic or thoracoscopic procedures. Ages ranged from 2 days to 20 weeks and weights from 1.5 to 5.0 kg. Procedures (numbers performed [n] and average operative times [t] in minutes) include Nissen fundoplication and gastrostomy (n = 58, t = 54), pyloromyotomy (n = 15, t = 15), patent ductus arteriosus (PDA) occlusion (n = 6, t = 50), pullthrough for Hirschsprung's disease (n = 4, t = 180, Ladd's procedure (n = 5, t = 65), ovarian cystectomy (n = 5, t = 35), lung biopsy (n = 5, t = 35), congenital diaphragmatic hernia repair (n = 3, t = 75), and other (n = 8, t = 12). The majority of procedures were performed with specially designed 3.4-mm instruments and a 2.7-mm 0° scope. Abdominal insufflation was kept at pressures of 10 to 14 mm Hg. All procedures were completed successfully endoscopically and the complication rate was 4.5%. The only death occurred after life support was removed after the results of a lung biopsy. Postoperative hospital stays were significantly shorter than standard open surgery (historical controls). This study demonstrates that advanced endosurgical techniques in infants are safe, effective, and associated with the same minimal morbidity and decreased hospital stays as in older patients.

Experience with endourologic techniques in infants and children

Experience with endourologic techniques in infants and children

Coarctation of the aorta. Repair with polytetrafluoroethylene patch aortoplasty.

The first successful surgical repair of coarctation of the aorta (CoAo) was performed in 1944, but during the years that followed a high incidence of recoarctation was seen, ranging from 20% to 86%. In response to that problem, the patch aortoplasty was introduced in 1957; however, true aneurysms were found in the aortic wall opposite the patch after Dacron patch aortoplasty, particularly when the coarctation ridge was excised. The purpose of our review was to evaluate the results of patch aortoplasty for CoAo using a relatively new material, polytetrafluoroethylene (PTFE), and an operative technique that does not involve resection of the coarctation ridge. Between 1979 and 1993, 125 infants and children underwent PTFE patch aortoplasty for CoAo; 111 of the procedures were primary repairs, and 14 were reoperations. Diagnoses were isolated CoAo (96 patients), CoAo and ventricular septal defect (15 patients), and CoAo with complex intracardiac anomaly (14 patients). Patient age at the time of repair ranged from 4 days to 17 years (mean age, 5.1 +/- 4.5 years). There were no instances of intraoperative mortality or paraplegia. There were 4 deaths from 10 to 40 days postoperatively, all in neonates (mean age, 33 days) who received additional intracardiac procedures for complex associated anomalies. Follow-up has ranged from 6 months to 12.5 years (mean, 4.5 +/- 3.2 years). All children had postoperative chest roentgenograms, 80 (66%) patients have had a postoperative echocardiogram and 16 (13%) a cardiac catheterization. One patient had successful repair of a false aneurysm 4 months postoperatively. No patient has developed a late true aneurysm. Of the patients < 1 month of age at the time of CoAo repair (12 patients), 6 patients had recurrent CoAo (gradient > 20 mm Hg) compared with only 4 recurrences in 97 patients > 1 month of age at the time of repair (P < .001). For children > 1 year of age, PTFE patch aortoplasty remains our procedure of choice for CoAo repair because of the low mortality rate, low recoarctation rate, and absence of late true aneurysms. We have stopped using this technique for infants < 1 month of age because of the high recurrence rate.

Evaluation of the Pulmonary Vasculature and Dynamics with Intravascular Ultrasound Imaging in Children and Infants

The ability to assess the pulmonary vasculature in pulmonary vascular disease by hemodynamic or histologic evaluation is limited. We sought to determine the feasibility of intravascular ultrasound techniques in infants and children and to assess simultaneously the morphology and dynamics of pulmonary arteries. Patients were seen in the Department of Pediatrics, Division of Pediatric Cardiology, Sophia Children's Hospital, Rotterdam, The Netherlands. We performed intravascular ultrasound imaging in 11 pediatric patients with congenital heart disease undergoing cardiac catheterization. Luminal diameter, area, and pulsatility were determined at two to five sites in the pulmonary branches. Pulmonary vascular reaction to 100% oxygen inhalation was studied. Patients weighed 4.1-51.0 kg (21.8 +/- 16.3 kg, mean +/- SD). Luminal diameters, areas, and pulsatilities could be determined reproducibly in arteries with diameters from 1.6 to 9.3 mm. In total 39 sites were studied in 11 patients. Pulsatility was related to vessel size (r = 0.81), although a substantial interindividual variation was present. After 100% oxygen inhalation, pulsatility increased in all arteries (from 20.0 +/- 3.3% to 25.9 +/- 2.9%, p < 0.05), and vasodilatation could be directly visualized, most prominently in the smallest arteries (percentage change in diameter, mean 7.4 +/- 2.8% versus -2.8 +/- 3.1% in the largest arteries, p < 0.001). Measurement of wall thickness was not feasible, but specific changes in the appearance of the wall structure could be recognized in a patient with severely elevated pulmonary vascular resistance. The specific advantages of intravascular ultrasound in assessing pulmonary vascular disease are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Transmission of pressure across the chest wall during the rapid thoracic compression technique in infants

During the rapid thoracic compression maneuver in infants, the transmission of pressure from compression jacket to pleural space and airway is less at functional residual capacity than at end inspiration. To examine whether reduced pressure transmission at functional residual capacity vs. higher lung volumes is explained by passive characteristics of the chest wall rather than by respiratory muscle activity, we assessed the pressure transmitted across the chest wall in nine anesthetized infants and young children after muscle relaxation. We measured esophageal and airway occlusion pressure during chest compressions at different lung volumes determined by varying distending pressure. In six subjects studied under static conditions, there was an approximately linear relationship between distending pressure and the proportion of pressure transmitted to the airway and esophagus from the compression jacket. The mean r2 value (95% confidence interval) was 0.80 (0.09) for pressure transmission to the airway and 0.85 (0.04) for pressure transmission to the esophagus. This relationship between lung volume and pressure transmission observed under static conditions was also demonstrated dynamically. Thus the reduced transmission of pressure from compression jacket to airway and pleural space at low lung volumes occurs independently of respiratory muscle activity.

Influence of duration mechanics measured of occlusion time on respiratory with the single‐breath technique in infants

To determine the effect of the length of end-inspiratory occlusion on the values of respiratory system compliance (Crs) and resistance (Rrs) calculated from the single-breath technique, 6 infants with cystic fibrosis were studied. End-inspiratory occlusions lasted between 0.3 and 1.2 seconds, and between 8 and 32 separate occlusions were made in each infant. Examination of the individual data showed a systematic tendency for Crs to decrease as the length of the airway occlusion increased, with statistical significance reached in two subjects. Using a random effects model, it was demonstrated that there was a decrease of 0.15 mL/cmH2O in Crs for each 0.1 s increase in occlusion time. The influence of length of plateau time for Crs was similar to that of total occlusion time. No such tendency was seen for Rrs. These data reinforce the current emphasis on greater standardization in the methodologies used for infant lung function testing and for more fully reporting methodological details.

Dynamic three-dimensional echocardiographic imaging of congenital heart defects in infants and children by computer-controlled tomographic parallel slicing using a single integrated ultrasound instrument.

Three-dimensional cardiac reconstruction generated from transesophageal interrogation can be performed using an integrated unit that captures, processes, and postprocesses tomographic parallel slices of the heart. This probe was used for infants and young children in the transthoracic position to evaluate the feasibility of producing three-dimensional cardiac images with capability for real-time dynamic display. Twenty-two infants and children (range 1 day-3.5 years) underwent image acquisition using a 16 mm 5 MHz 64 element probe placed over the precordium. Two infants were also imaged from the subcostal position. Data was obtained and stored over a single cardiac cycle after acceptable cardiac and respiratory gating intervals were met. The transducer was advanced in 0.5-1 mm increments over the cardiac structures using identical acquisition criteria. The images were reconstructed from the stored digital cubic format and could be oriented in any desired plane. In 9 of the 22 infants the images obtained were of optimal quality. The images obtained displayed normal cardiac structures emphasizing depth relationships as well as visualization of planes not generally demonstrated by two-dimensional imaging. Several lesions were also depicted in a unique fashion using this technique. Though the method employed was limited by movement artifact and reconstruction time, the quality of the three-dimensional display was excellent and enhanced by real-time demonstration. The transthoracic approach was successful in capturing sufficient data to create three-dimensional images, which may have further application in more accurate diagnosis of complex cardiac abnormalities and generation of planes of view which could duplicate surgical visualization of a lesion. Further assessment of the technique in infants with congenital heart disease is warranted.

Internal jugular vein catheterization in infants undergoing cardiovascular surgery: an analysis of the factors influencing successful catheterization.

Central venous catheterization for pressure monitoring and drug administration is often important in the anesthetic management of infants undergoing cardiovascular surgery. We examined the effects of patient age, weight, and central venous pressure and the experience of the anesthesiologist on the rate of successful catheterization and catheterization time of the internal jugular vein (IJV) in a prospective study. We studied 106 infants undergoing IJV catheterization for cardiovascular surgery over a 7-mo period at our institution. We catheterized the IJV by the high approach. The direct venipuncture or the Seldinger method was used according to the patient's weight. Overall successful catheterization rate was 97.2%, and the average catheterization time was 353 +/- 21 s (mean +/- SEM). Complications included arterial puncture in 12 cases (11.3%), hematoma formation in four cases (3.8%), and catheter malposition in two cases (1.9%), but pneumothorax was not observed. When a patient was younger than 3 mo or weighed less than 4.0 kg, successful catheterization rate decreased significantly to 81.3% and 78.6%, respectively. Catheterization time was inversely correlated with both age and weight, whereas central venous pressure did not affect either successful catheterization rate or catheterization time. We were unable to demonstrate that the experience of the anesthesiologist plays a significant role in the success or complication of the catheterization procedure. Our results indicate that IJV catheterization by the high approach is a reliable and useful technique in infants, and that the weight and age of the patient significantly influence the rate of successful catheterization.

Evaluation of nasal impedance using the forced oscillation technique in infants

By applying oscillations to the respiratory system through a rigid face mask, the infant-adapted Lándsér forced oscillation technique measures impedance of the total respiratory system including the nose, at frequencies from 4 to 52 Hz. The present study was aimed at evaluating nasal impedance in infants from consecutive forced oscillation measurements through both nostrils and each nostril separately, using a simple electrical model. In 30 asthmatic infants with varying degrees of nasal obstruction, aged 1-16 months, calculated nasal resistance (Rn) at 24 Hz ranged from 1 to 16 cm H2O.L-1.s. The ratio of Rn to total respiratory system resistance varied between 1 and 48% (mean: 16%). In seven non-asthmatic infants, aged 0-12 months, Rn was between 1 and 11 cm H2O.L-1.s. Nasal patency (evaluated clinically) was correlated with the calculated Rn (P less than 0.05). Rn showed almost no frequency dependence between 24 and 48 Hz as demonstrated by a mean slope of -0.09 +/- 0.08 cm H2O.s2/L for the asthmatic and of -0.08 +/- 0.07 for the non-asthmatic infants. In seven of the asthmatic infants the differences between two Rn determinations at a 45 min interval ranged from -1.7 to 3.8 cm H2O.L-1.s-1 at 24 Hz and from -3.6 to 1.0 at 48 Hz. Changes in Rn did not correlate with changes in total respiratory system resistance (P greater than 0.05). In conclusion, nasal impedance can be approximated from three consecutive measurements through both nostrils and through each nostril separately.

Balloon aortic valvuloplasty in children

The technique of balloon aortic valvuloplasty has been used in infants, children, and adults since its first description in 1983. Immediate results reported by several workers and intermediate-term results by a few workers appear encouraging. Complications are minimal although potential for arterial complications and aortic insufficiency should be recognized. Significant restenosis rates at intermediate-term follow-up have been reported and could be minimized by reducing the risk factors associated with recurrence. Echo-Doppler studies are useful in follow-up evaluation of balloon valvuloplasty. The results seem to compare favorably with those following surgical valvotomy. The indications are essentially the same as those used for surgery; a gradient in excess of 80 mmHg irrespective of symptoms or a gradient greater than or equal to 50 mmHg with symptoms or ST-T wave changes. Previous surgical valvotomy is not a contraindication for balloon valvuloplasty. The technique is applicable to subaortic membranous stenosis as well. Thus far only one- to two-year follow-up results are available. Five- to ten-year follow-up results to document long-term effectiveness of balloon aortic valvuloplasty are needed. Miniaturization of currently bulky dilating catheter systems and improving rapidity of inflation/deflation of balloons are necessary to increase safety and effectiveness of these techniques in infants and children. Meticulous attention to the details of the technique and further refinement of the procedure may further increase effectiveness and reduce the complication rate.

Computer analysis of physical factors affecting the use of the interrupter technique in infants.

The interrupter technique involves measuring pressure changes at the airway opening following abrupt interruption of airflow, and relies on rapid equilibration of alveolar and airway opening pressures. Following airway occlusion one generally sees a rapid change in airway opening pressure, Pinit, which reflects the resistive pressure drop across the system, followed by a secondary, slower pressure change, Pdif, which reflects the tissue visco-elastic properties together with any redistribution of gases occurring between lung units at different pressure at the time of interruption. Physical factors in the measuring equipment, i.e., the time taken for valve closure and the presence of a proximal compliant compartment, can cause errors in the calculation of resistance and elastance using the interrupter technique. A computer model was used to determine the effects of these factors on the calculation of resistance and elastance in normal infants, premature infants, and infants with bronchopulmonary dysplasia. The elastance from 25 ml of dead space gas did not introduce significant errors into the measurements in any group of infants, but the presence of an unsupported upper airway caused errors of up to 245%. Increasing valve closure time introduced progressively larger errors into the calculation of resistance and elastance. To keep these errors acceptably small, an occlusion valve should close in 20 ms or less.

Evaluation of pulmonary blood supply by nuclear magnetic resonance imaging in patients with pulmonary atresia

Nuclear magnetic resonance (NMR) imaging defines the blood pool without the need for contrast medium. Consequently, it may be useful for defining the pulmonary circulation in patients with pulmonary atresia, in whom opacification of these vessels can be problematic.Ten patients with pulmonary atresia were evaluated by gated NMR imaging. The morphology of the right ventricular outflow tract, the size and the course of the central pulmonary vessels and the source of the collateral supply to the lung were assessed. Central pulmonary arteries were identified and measured in 9 of the 10 patients. One patient had no detectable central pulmonary arteries. Angiography confirmed the NMR findings in all but two patients, in whom NMR scanning visualized a main pulmonary artery that was not seen on angiography. Collateral arteries arising from the aorta or the arch vessels, as well as intracardiac malformations and aortic arch anomalies, were identified in all 10 patients. In six patients with palliative surgery, NMR imaging correctly demonstrated all patent shunts.Nuclear magnetic resonance imaging appears to be an effective noninvasive technique for evaluating patients with pulmonary atresia. However, tomographic thickness and spatial resolution are still limiting factors for this technique in infants.

Tuning curve widths of infants and adults in simultaneous and nonsimultaneous masking

Tuning curve widths were estimated using the pulsation threshold (PT) technique for infants, 6‐month‐olds, and adults. The observer‐based psychoacoustic procedure [L. W. Olsho et al., Dev. Psychol., in press (1987)] was the test procedure. Listeners discriminated a train of alternating masker and probe tone bursts from a train of masker tone bursts presented with a continuous probe tone. These stimuli were presented in a background of broadband noise at 20‐dB pressure spectrum level. The probe level was 10 dB SL. PTs were obtained at the tuning curve tip and at two points, one above and one below the probe frequency, 10 dB above the tip. The resulting Q10s were compared to those obtained in simultaneous masking for 6‐month‐olds and adults [L. W. Olsho, Inf. Behav. Dev. 8, 371–384 (1985)]. Adult Q10s were significantly greater for PT tuning curves at 500, 1000, and 4000 Hz. Infant PT Q10s were significantly greater than simultaneous masking Q10s at 500 and 1000 Hz, but not at 4000 Hz. [Work supported by NIH.]

Ventilatory pattern following diphtheria-tetanus-pertussis immunization in infants at risk for sudden infant death syndrome.

To evaluate the effects of diphtheria-tetanus-pertussis (DTP) immunization on the ventilatory pattern during sleep in infants at increased risk for sudden infant death syndrome (SIDS), we performed overnight pneumograms (recordings of ventilatory pattern and electrocardiogram) on 30 control infants, 46 infants with unexplained apnea, and 33 subsequent siblings of SIDS victims the night before and the night following a DTP immunization. Pneumograms were quantitated for total sleep time, longest apnea (in seconds), total duration of apneas longer than 6 s (in minutes), and total periodic breathing (in minutes). Following the DTP immunization there was no significant change in any criterion quantitated on pneumograms from any group except for a decrease in periodic breathing in the unexplained apnea group. We conclude that DTP immunization does not increase abnormalities of the ventilatory pattern as recorded by the pneumogram technique in infants at increased risk for SIDS.

Closed Circuit Anesthesia in Infants and Children

A closed-system low-flow technique with enflurane, halothane, or isoflurane as the sole anesthetic was used in three groups of ten children each. Anesthesia was induced by injection into the expiratory limb of a priming standard dose of the liquid anesthetic, followed by additional doses at 15, 30, 60, and 90 sec, and 2, 3, and 4 min. Further injections following the "square root of time" sequence were used for maintenance. Volumes of anesthetics used averaged 3.7 +/- 1.1 ml for enflurane, 2.3 +/- 1.1 ml for halothane, and 3.0 +/- 0.9 ml for isoflurane. These volumes were higher than predicted on theoretical grounds, as was the frequency with which anesthetics had to be injected. Closed-system low-flow anesthesia is a practical, economical, and nonpolluting technique in pediatric patients. Complications associated with isoflurane suggest, however, that isoflurane is not as satisfactory as enflurane or halothane when using this technique in infants and children.

Injection technique in infants

Injection technique in infants

Injection Technique in Infants

To the Editor.— The coverage of current controversies surrounding the use of diphtheria, tetanus, pertussis (DTP) vaccine in the MEDICAL NEWS section (1982;248:12) was timely and generally excellent. How very unfortunate, however, that an article concerned with the complications of immunization procedures contained a photograph that depicts a dangerous and obsolete technique of intramuscular (IM) injection. The risk of sciatic nerve injury associated with gluteal injections in young children is substantial.1It is my impression that it is now universally accepted that infants should receive IM injections only in the anterolateral aspect of the midthigh. I am surprised and concerned that the Centers for Disease Control, Atlanta, provided such a photograph.

1396 THE EFFECTS OF PATENT DUCTUS ARTERIOSUS (PDA) ON PULSATILE FLOW IN THE ANTERIOR CEREBRAL ARTERIES (ACA)

The noninvasive measurement of pulsatile flow in the ACA is possible with a transcutaneous Doppler technique in infants with an open anterior fontanel. A pulsatility index (PI), calculated from the systolic and diastolic amplitudes of flow, represents resistance to flow (range 0.0-1.0). The Doppler technique has also been used to diagnose PDA. We have used these techniques to study the relationship between PDA and cerebral blood flow in the ACA. PDA was confirmed by radiological and echocardiographic studies. In an ongoing study, 5 infants (birthweight <1500 g) had increase in PI at the time of development of PDA and decrease in PI to normal after closure of the PDA. PI values (mean ± SD) prior to, during and following closure of the PDA were 0.69 ± 0.03, 0.89 ± 0.04 and 0.69 ± 0.01 respectively (N=0.66 ± 0.06). Serial values of PI in a representative case are shown. Arrow represents therapy for closure of PDA. The above data demonstrate decreased pulsatile flow in the ACA at the time of development of PDA and abrupt return to normal following closure of the PDA. These observations re: rapid fluctuations in cerebral blood flow may have implications for the genesis of ischemic cerebral injury and/or the development of intra-ventricular hemorrhage in the premature infant.

Skin-puncture and blood-collecting techniques for infants.

Skin-puncture and blood-collecting techniques for infants.