Sedated Infants Research Articles

A novel method for infant multiple breath washout: First report in clinical practice.

Lung clearance index (LCI), measured using multiple breath inert gas washout (MBW) is a potentially useful test in infants with respiratory disease, particularly cystic fibrosis (CF). Clinical use is limited however by the need for specialist staff and equipment. We have previously described a novel method for infant MBW suitable for use outside of specialist laboratories. This study describes its performance in vivo in infants with CF and healthy controls, including a limited comparison with the respiratory mass spectrometer. Children aged less than 2 years with CF and controls underwent MBW testing on a single occasion. The practical applicability of the system was determined by the number of successful duplicate tests and within-subject repeatability. Twenty-five children (seven with CF, 18 healthy controls, all sedated with chloral hydrate) attempted MBW. Twenty patients (seven with CF) successfully underwent duplicate testing (80% success rate). Mean within-subject coefficient of variation for functional residual capacity (FRC) was 7.2% and for LCI 5.9%. Comparison of LCI with the mass spectrometer was limited but gave very similar values for LCI and FRC in those patients who underwent technically adequate tests with both methods. We have described a new MBW method that is feasible and reproducible in sedated infants. Results fall within the expected range, and well within accuracy limits set by international guidelines. This could provide a more accessible alternative to previously described systems for infant MBW, and overcomes many of the technical challenges inherent in conventional MBW.

Chapter 34 - Visually evoked potentials

The term visually evoked potential (VEP) refers to electrical potentials recorded from scalp overlying visual cortex that have been extracted from the electroencephalogram by signal averaging. Usually the recording electrode is placed on the midline of the occipital scalp at the back of the head. VEPs are used to quantify the functional integrity of the optic nerves, pathways to the visual cortex of the brain, and occipital cortex. Any abnormality that affects the visual pathways or visual cortex in the brain can affect the VEP. Examples include slowing neuronal transmission, such as produced by myelin plaques common in multiple sclerosis, or gliomas on optic nerves in neurofibromatosis slowing the speed of the VEP wave peaks. Compression of the optic pathways, such as from hydrocephalus or from a pituitary tumor, affects the VEP. There are several methods of recording VEPs. In patients over about 3 years of age VEPs are usually recorded using a video monitor presenting patterned stimuli. In sedated patients and infants, flashes of light from a strobe flash or an array of LEDs are used to stimulate the eye. Multifocal VEPs expand the visual field topographic mapping to beyond 40 degrees of the central visual field.

SU‐F‐T‐83: Infant Total Skin Electron Therapy Using Five Fields Technique

Purpose:We were presented with a 9 month old boy with Relapsed Acute Myeloid Leukemia (AML) involving the skin. The plan was to treat the entire skin using 6 MeV electrons with the infant under complete anesthesia. The purpose of this work is to commission the 6 MeV electron beam and to develop a technique that can be used to deliver total skin dose to infants with minimal patient immobilization.Methods:A baby mannequin phantom that mimics the child's length was used to determine the best technique to treat the infant. The 76 cm long phantom was placed on the floor. The phantom was placed in four unique immobilization devices to simulate four different treatment positions (anterior, posterior, left lateral and right lateral). Radiochromic films were used to determine beam profile in both axial and radial directions, and percent depth dose (PDD). Absolute calibration of the machine output at 214 cm distance was measured using an Exradin A11 parallel‐plate ion chamber. A 1.0 cm plexiglass scatter plate was inserted in the collimator. Mosfet dosimeters were used for dose verification for phantom and and patient.Results:At 214 cm source to surface distance (SSD) using gantry angle of + 20o from vertical beam flatness is + 10% in the radial direction over a region of 70 cm and + 4% in the axial direction over 60 cm. A five field arrangement was determined to optimally deliver the desired dose with > 90% uniformity. The fifth field was used to boost the head vertex.Conclusion:It is possible to treat sedated infants with total skin dose using five positions. Four positions were enough to cover the body and the fifth position boosts the vertex of the head. All fractions can be reproduced accurately daily because of the patient's stable immobilization.

Hémangioblastome rétinien responsable d’un syndrome de traction papillaire au cours d’une maladie de Von Hippel-Lindeau

The term visually evoked potential (VEP) refers to electrical potentials recorded from scalp overlying visual cortex that have been extracted from the electroencephalogram by signal averaging. Usually the recording electrode is placed on the midline of the occipital scalp at the back of the head. VEPs are used to quantify the functional integrity of the optic nerves, pathways to the visual cortex of the brain, and occipital cortex. Any abnormality that affects the visual pathways or visual cortex in the brain can affect the VEP. Examples include slowing neuronal transmission, such as produced by myelin plaques common in multiple sclerosis, or gliomas on optic nerves in neurofibromatosis slowing the speed of the VEP wave peaks. Compression of the optic pathways, such as from hydrocephalus or from a pituitary tumor, affects the VEP. There are several methods of recording VEPs. In patients over about 3 years of age VEPs are usually recorded using a video monitor presenting patterned stimuli. In sedated patients and infants, flashes of light from a strobe flash or an array of LEDs are used to stimulate the eye. Multifocal VEPs expand the visual field topographic mapping to beyond 40 degrees of the central visual field.

40-Hz multiple auditory steady-state responses to narrow-band chirps in sedated and anaesthetized infants

ObjectiveThe general consensus to date has been that a stimulus repetition rate of 40Hz is not appropriate for the recording of auditory steady-state responses (ASSR) in sedated or anaesthetized infants. The aim of this study was to investigate whether reliable 40-Hz ASSR thresholds can be obtained in sedated infants using narrow-band chirp stimuli in the clinical routine. Methods40-Hz auditory brainstem responses (ABR) and 40-Hz ASSR were recorded in 34 infants below the age of 48 months under sedation or under general anaesthesia. ABR were evoked by broad-band chirp stimuli with a flat amplitude spectrum. ASSR were recorded simultaneously from both ears with an adaptive multiple stimulus paradigm using four narrow-band chirps centred at 500, 1000, 2000 and 4000Hz. ABR and ASSR thresholds were evaluated to determine differences between the estimates from the two methods. ResultsDespite of sedation and anaesthesia, large wave V amplitudes of the chirp evoked 40-Hz ABR were found at levels as low as 10dB above the individual ABR threshold. ASSR thresholds for stimulus repetition rates of 40Hz could be consistently estimated in all 34 infants. Thresholds estimated from the ASSR for the four frequencies of the narrow-band chirps and the threshold derived from the broad-band chirp ABR differ, on average by 3.7dB for the frequency range of 1000–2000Hz and 7.1dB for the frequency range from 2000 to 4000Hz. ConclusionIn contrast to the general assumption that 40-Hz ASSR are not appropriate for threshold estimation in infants our results demonstrate that multiple ASSR with a stimulus repetition rate of 40Hz can be recorded in sedated and anaesthetized infants using narrow-band chirps. Threshold estimates obtained with 40-Hz ASSR are, on average, slightly higher than those obtained with chirp evoked ABR but allow for a frequency specific characterisation of the hearing ability.

A Clinical Tool for Reducing Central Nervous System Depression among Neonates Exposed to Codeine through Breast Milk

BackgroundNeonates are commonly exposed to maternal codeine through breast milk. Central Nervous System (CNS) depression has been reported in up to 24% of nurslings following codeine exposure. In 2009, we developed guidelines to improve the safety of codeine use during breastfeeding based on previously established pharmacogenetic and clinical risk factors. The primary objective of this study was to prospectively evaluate the effectiveness of these guidelines in ensuring neonatal safety.Methods and FindingsWomen taking codeine for pain following caesarean section were given safety guidelines, including advice to use the lowest codeine dose for no longer than four days and to switch to a non-opioid when possible. Mothers provided a saliva sample for analysis of genes involved in opioid disposition, metabolism and response. A total of 238 consenting women participated. Neonatal sedation was reported in 2.1% (5/238) of breastfeeding women taking codeine according to our safety guidelines. This rate was eight fold lower than that reported in previous prospective studies. Women reporting sedated infants were taking codeine for a significantly longer period of time (4.80±2.59 days vs. 2.52±1.58 days, p = 0.0018). While following the codeine safety guidelines, mothers were less likely to supplement with formula, reported lower rates of sedation in themselves and breastfed more frequently throughout the day when compared to previously reported rates. Genotyping analysis of cytochrome p450 2D6 (CYP2D6), uridine-diphosphate glucuronosyltransferase (UGT) 2B7, p-glycoprotein (ABCB1), the mu-opioid receptor (OPRM1) and catechol-o-demethyltransferase (COMT) did not predict codeine response in breastfeeding mother/infant pairs when following the safety guidelines.ConclusionsThe only cases of CNS depression occurred when the length of codeine use exceeded the guideline recommendations. Neonatal safety of codeine can be improved using evidence-based guidelines, even in those deemed by genetics to be at high risk for toxicity.

BOLD fMRI in infants under sedation: Comparing the impact of pentobarbital and propofol on auditory and language activation

To elucidate differences in the disruption of language network function, as measured by blood oxygenation level-dependent (BOLD) contrast functional MRI (fMRI), attributable to two common sedative agents administered to infants under clinical imaging protocols. The sedatives pentobarbital (Nembutal) and Propofol, administered clinically to infants at 1 year of age, were compared with respect to BOLD activation profiles in response to passive story-listening stimulation. An intermittent event-related imaging protocol was used with which the temporal evolution of language processing resulting from this stimulation was explored. Propofol and Nembutal were found to have distinct and complementary responses to story-listening. Propofol exhibited more activation in higher processing networks with increasing response toward the end of narrative stimulus. Nembutal, in contrast, had much more robust activation of primary and secondary sensory cortices but a decreasing response over time in fronto-parietal default-mode regions. This may suggest a breakdown of top-down feedback for Propofol versus the lack of bottom-up feed-forward processing for Nembutal. Two popular sedative agents for use in children for clinical fMRI were found to induce distinct alteration of activation patterns from a language stimulus. This has ramifications for clinical fMRI of sedated infants and encourages further study to build a framework for more confident interpretation.

Does the Use of an Immobilizer Provide a Quality MR Image of the Brain in Infants?

Magnetic resonance imaging (MRI) provides key clinical and diagnostic information for care of neonates and young infants. However, to obtain quality images, they need to be motionless in the scanner, often with the aid of sedation medications, which put them at risk for complications. An immobilizer device (an airtight, chambered device that safely and securely fastens around the infant without applying pressure) allows the infant to feel snug and warm, sleepy and motionless, and can be used as an alternative to sedation for this population. We conducted a retrospective, descriptive, comparative study at The Children’s Hospital of Philadelphia MRI Department in the Division of Radiology. Inclusion criteria were infants less than or equal to 90 days of age, weighing at least 2kg, requiring a MRI brain scan that is predicted to take no more than 60min to complete. We obtained data on 36 patients who received sedation medications for their brain MRI scan, and 36 patients who completed their brain MRI scan without the use of sedation medication, but rather were in the “feed and immobilize” group. Results of the study showed that brain MRIs on sedated infants took longer, and those infants were more likely to experience oxygen desaturation and require supplemental oxygen post-MRI. Most importantly, we found that the MR images were considered diagnostic in 100% of the sedated infants and 94% of the immobilized infants, although significantly more immobilized infants had artifact from motion than sedated infants. Implications for practice include potential cost saving and increased patient’s safety (e.g., more stable respiratory status).

Quantitative assessment of chronic lung disease of infancy using computed tomography

The aims of this study were to determine whether infants and toddlers with chronic lung disease of infancy (CLDI) have smaller airways and lower lung density compared with full-term healthy controls. Multi-slice computed tomography (CT) chest scans were obtained at elevated lung volumes during a brief respiratory pause in sedated infants and toddlers; 38 CLDI were compared with 39 full-term controls. For CLDI subjects, gestational age at birth ranged from 25 to 29 weeks. Airway size was measured for the trachea and the next three to four generations into the right lower lobe; lung volumes and tissue density were also measured. The relationship between airway size and airway generation differed between the CLDI and full-term groups; the sizes of the first and second airway generations were larger in the shorter CLDI than in the shorter full-term subjects. The increased size in the airways in the CLDI subjects was associated with increasing mechanical ventilation time in the neonatal period. CLDI subjects had a greater heterogeneity of lung density compared with full-term subjects. Our results indicate that quantitative analysis of multi-slice CT scans at elevated volumes provides important insights into the pulmonary pathology of infants and toddlers with CLDI.

Ventilation homogeneity improves with growth early in life

Some studies have suggested that lung clearance index (LCI) is age-independent among healthy subjects early in life, which implies that ventilation distribution does not vary with growth. However, other studies of older children and adolescents suggest that ventilation becomes more homogenous with somatic growth. We describe a new technique to obtain multiple breath washout (MBWO) in sedated infants and toddlers using slow augmented inflation breaths that yields an assessment of LCI and the slope of phase III, which is another index of ventilation inhomogeneity. We evaluated whether ventilation becomes more homogenous with increasing age early in life, and whether infants with chronic lung disease of infancy (CLDI) have increased ventilation inhomogeneity relative to full-term controls (FT). FT (N = 28) and CLDI (N = 22) subjects between 3 and 28 months corrected-age were evaluated. LCI decreased with increasing age; however, there was no significant difference between the two groups (9.3 vs. 9.5; P = 0.56). Phase III slopes adjusted for expired volume (S(ND)) increased with increasing breath number during the washout and decreased with increasing age. There was no significant difference in S(ND) between full-term and CLDI subjects (211 vs. 218; P = 0.77). Our findings indicate that ventilation becomes more homogenous with lung growth and maturation early in life; however, there is no evidence that ventilation inhomogeneity is a significant component of the pulmonary pathophysiology of CLDI.

Induced Hypothermia for Infants With Hypoxic- Ischemic Encephalopathy Using a Servo-Controlled Fan: An Exploratory Pilot Study

Several trials suggest that hypothermia is beneficial in selected infants with hypoxic-ischemic encephalopathy. However, the cooling methods used required repeated interventions and were either expensive or reported significant temperature variation. The objective of this pilot study was to describe the use, efficacy, and physiologic impact of an inexpensive servo-controlled cooling fan blowing room-temperature air. A servo-controlled fan was manufactured and used to cool 10 infants with hypoxic-ischemic encephalopathy to a rectal temperature of 33 degrees C to 34 degrees C. The infants were sedated with phenobarbital, but clonidine was administered to some infants if shivering or discomfort occurred. A servo-controlled radiant warmer was used simultaneously with the fan to prevent overcooling. The settings used on the fan and radiant warmer differed slightly between some infants as the technique evolved. A rectal temperature of 34 degrees C was achieved in a median time of 58 minutes. Overcooling did not occur, and the mean temperature during cooling was 33.6 degrees C +/- 0.2 degrees C. Inspired oxygen requirements increased in 6 infants, and 5 infants required inotropic support during cooling, but this was progressively reduced after 1 to 2 days. Dehydration did not occur. Five infants shivered when faster fan speeds were used, but 4 of the 5 infants had hypomagnesemia. Shivering was controlled with clonidine in 4 infants, but 1 infant required morphine. Servo-controlled fan cooling with room-temperature air, combined with servo-controlled radiant warming, was an effective, simple, and safe method of inducing and maintaining rectal temperatures of 33 degrees C to 34 degrees C in sedated infants with hypoxic-ischemic encephalopathy. After induction of hypothermia, a low fan speed facilitated accurate temperature control, and warmer-controlled rewarming at 0.2 degrees C increments every 30 minutes resulted in more appropriate rewarming than when 0.5 degrees C increments every hour were used.

Effect of brain magnetic resonance imaging on body core temperature in sedated infants and children

Children undergoing magnetic resonance imaging (MRI) under sedation are at risk of hypo- or hyperthermia. The effect of brain MRI at differing magnetic field strengths on body core temperature in sedated infants and young children has not been reported previously. Two groups of 38 infants and children (aged 1 month to 6 yr 5 months) underwent brain MRI for different indications related to cerebral diseases, at 1.5 Tesla (T) and 3 T MRI units, respectively. All patients received deep sedation comprising midazolam, nalbuphine, and propofol. Pre-scan and post-scan temperatures were measured at the right tympanic and at rectal sites. No active warming devices were used during the procedures. Body core temperature measurements were similar between right tympanic and rectal site before and after the scans. After 1.5 T scans, the median (IQR) increase from pre-scan to post-scan tympanic temperature was 0.2 degrees C (0.1-0.3), and the median (IQR) rectal temperature increase was 0.2 degrees C (0-0.3) (P<0.001). After 3 T scans, the median (IQR) tympanic temperature increase was 0.5 degrees C (0.4-0.7), and the median (IQR) rectal temperature increase was 0.5 degrees C (0.3-0.6) (P<0.001). Body core temperature increased significantly during 1.5 and 3 T examinations; this increase was more profound during 3 T MRI. Patient heating occurred despite minimal efforts to reduce passive heat loss under sedation and without the use of warming devices.

Expired nitric oxide and airway reactivity in infants at risk for asthma

Family histories of atopy, as well as histories of atopic dermatitis and food allergy, are important risk factors for an infant to have asthma. Although atopic sensitization appears to contribute to the development of asthma, it is unclear when the airways become involved with the atopic process and whether airway function relates to the atopic characteristics of the infant. We sought to evaluate whether atopic infants without prior episodes of wheezing have increased expired nitric oxide (eNO) levels and heightened airway reactivity. Infants with eczema were recruited, and atopic status was defined by specific IgE levels to foods or aeroallergens and total IgE levels. eNO, forced expiratory flow at 75% exhaled volume (FEF(75)), and airway reactivity to inhaled methacholine were measured in sedated infants. Airway reactivity was quantified by using the provocative concentration to decrease FEF(75) by 30%. Median age for the 114 infants evaluated was 10.7 months (range, 2.6-19.1 months). Infants sensitized to egg or milk compared with infants sensitized to neither egg nor milk had lower flows (FEF(75): 336 vs 285 mL/s, P < .003) and lower lnPC(30) (mg/mL) provocative concentrations to decrease FEF(75) by 30% (-0.6 vs -1.2, P < .02) but no difference in eNO levels. Infants with total serum IgE levels of greater than 20 IU/mL had higher eNO levels compared with infants with IgE levels of 20 IU/mL or less (14.6 vs 11.2 ppb, P < .023) but no difference in forced flows or airway reactivity. Our findings suggest that atopic characteristics of the infant might be important determinants of the airway physiology of forced expiratory flows, airway reactivity, and eNO.

Combined spinal – epidural anesthesia in major abdominal surgery in high‐risk neonates and infants

Combined spinal-epidural anesthesia (CSE-A) is reportedly safe and effective for the pediatric population in infraumbilical surgery. Our main purpose was to describe our experience of this technique in neonates and infants undergoing elective major upper abdominal surgery. Spinal anesthesia was performed in 28 neonates and infants with isobaric bupivacaine 0.5%, 1 mg.kg(-1) followed by placement of a caudal epidural catheter to thoracic spinal segments. The catheter tip position was confirmed radiographically. Respiratory and hemodynamic data were collected before and after the CSE-A and throughout the operation, as a measure of anesthetic effectiveness. Complications related to the anesthesia technique were collected as a measure of the anesthetic technique safety. Satisfactory surgical anesthesia was achieved in 24 neonates and infants, four patients were converted to general anesthesia. Respiratory and hemodynamic variables did not change significantly during surgery, compared with baseline values: oxygen saturation (P = 0.07), systolic and diastolic blood pressures (P = 0.143, P = 0.198 respectively), heart rate (P = 0.080) and respiratory rate (P = 0.127). However, twenty infants were fussy during the surgical procedures and were calmed with intravenous midazolam; our patients required oxygen supplementation and transient manual ventilation intraoperatively. Combined spinal-epidural anesthesia could be considered as an effective anesthetic technique for elective major upper abdominal surgery in awake or sedated neonates and infants, and could be used cautiously by a pediatric anesthesiologist as an alternate to general anesthesia in high-risk neonates and infants undergoing upper gastrointestinal surgery.

Noninvasive monitoring of chest wall movement in infants using laser

Traditionally, non-invasive monitoring of tidal volume in infants has been performed using impedance plethysmography analyzed using a one or two compartment model. We developed a new laser system for use in infants, which measures antero-posterior movement of the chest wall during quiet sleep. In 24 unsedated or sedated infants (11 healthy, 13 with respiratory disease), we examined whether the analysis of thoracoabdominal movement based on a three compartment model could more accurately estimate tidal volume in comparison to V(T) measured at the mouth. Using five laser signals, chest wall movements were measured at the right and left, upper and lower ribcage and the abdomen. Within the tidal volume range from 4.6 to 135.7 ml, a three compartment model showed good short term repeatability and the best agreement with tidal volume measured at mouth (r(2) = 0.86) compared to that of a single compartment model (r(2) = 0.62, P < 0.0001) and a two compartment model (r(2) = 0.82, P < 0.01), particularly in the presence of respiratory disease. Three compartment modeling of a 5 laser thoracoabdominal monitoring permits more accurate estimates of tidal volume in infants and potentially of regional differences of chest wall displacement in future studies.

Reply to the Editor

We thank Benallal for his comments on our article and appreciate his remarks. Our study was specifically designed to assess the importance of measured oxygen consumption (VO2) in the preoperative diagnostic hemodynamic evaluation during cardiac catheterization and to assess whether published formulas allow a reliable calculation of VO2. We did not intend to develop a new formula to assume VO2. Our results emphasize that both the Krovetz-Goldbloom formula,1Krovetz L.J. Goldbloom S. Normal standards for cardiovascular data. I. Examination of the validity of cardiac index.Johns Hopkins Med J. 1972; 130: 174-186PubMed Google Scholar which had been used to this point in our institution, and the more commonly used formula published by LaFarge and Miettinen2LaFarge C.G. Miettinen O.S. The estimation of oxygen consumption.Cardiovasc Res. 1970; 4: 23-30Crossref PubMed Scopus (319) Google Scholar are not feasible in all patients to assume VO2 and thereby calculate cardiac output by the Fick principle. Li and colleagues3Li J. Bush A. Schulze-Neick I. Penny D.J. Redington A.N. Shekerdemian L.S. Measured versus estimated oxygen consumption in ventilated patients with congenital heart disease the validity of predictive equations.Crit Care Med. 2003; 31: 1235-1240Crossref PubMed Scopus (58) Google Scholar presented the important conclusion that other predictive equations published by Lundell and associates,4Lundell B.P.W. Casas M.L. Wallgren C.G. Oxygen consumption in infants and children during heart catheterization.Pediatr Cardiol. 1996; 17: 207-213Crossref PubMed Scopus (42) Google Scholar Wessel and colleagues,5Wessel H.U. Rorem D. Muster A.J. Acevedo R.E. Paul M.H. Continuous determination of oxygen uptake in sedated infants and children during cardiac catheterization.Am J Cardiol. 1969; 24: 376-385Abstract Full Text PDF PubMed Scopus (29) Google Scholar and Lindahl6Lindahl S.G.E. Oxygen consumption and carbon dioxide elimination in infants and children during anaesthesia and surgery.Br J Anaesth. 1989; 62: 70-76Crossref PubMed Scopus (55) Google Scholar also do not accurately estimate VO2. All these formulas were developed to offer a suitable and reliable method to assume VO2 in order to simplify the calculation of hemodynamic parameters. However, these formulas cannot be used in all patients and settings. As Benallal pointed out, these formulas include coefficients depending on characteristics of the population investigated in these studies. The difference between measured and assumed VO2 might be due to a population difference. In addition, it is also influenced essentially by other conditions such as the mode of general anesthesia and relaxation used in different institutions. It is difficult to identify feasible coefficients to develop a formula fitting to all conditions of hemodynamic evaluation during cardiac catheterization. Moreover, we are convinced that our population of 143 patients is too small to identify and validate suitable coefficients for a new formula. LaFarge and Miettinen derived their most commonly used formulas from a multivariate analysis of covariance applied to data on a series of 879 patients. A new modeling for each populationThe Journal of Thoracic and Cardiovascular SurgeryVol. 131Issue 2PreviewI read with great interest the recently published study by Fakler and associates1 in the August 2005 issue of the Journal. They found, in their investigation, a poor agreement between the measured oxygen consumption (VO2) and the VO2 estimated using the formulas of Krovetz and Goldbloom2 and LaFarge and Miettinen.3 According to the Krovetz-Goldbloom formula, the mean difference was −53 mL/min/m2 and the limits of agreement were −95.5 and −11.1 mL/min/m2 for the lower and upper limits, respectively. Full-Text PDF

Heartbeat assessment in infants: A comparison of four clinical methods

To compare the performance of four clinical methods (apex ear auscultation; brachial, carotid, and femoral pulse palpation) for detecting and counting heart beat in infants. Cross-sectional, repeated-measures study design. Prospective data collection. A postanesthesia care unit of a pediatric teaching hospital in Italy. Fifty-six normotensive sedated infants, aged 1-12 mos, were evaluated by 14 pediatric basic life support (PBLS)-qualified health professionals. None. The proportion of successful heartbeat detections ranged from 60% with carotid pulse palpation to 98% with apex auscultation. Among successful detections, apex auscultation proved to be the most rapid way to detect heart rate (median, 4 secs) and the most accurate with a median discrepancy of 8 beats/min (vs. 12 with the other methods) from the electrocardiographic results. Differences between apex auscultation and pulse palpation were statistically significant (p < .0001). In contrast, no significant differences were found among the three methods of pulse checking. Apex listening is the most successful, rapid, and accurate method to detect and count the heartbeat by PBLS-certified professionals in normotensive infants without instruments. Pulse checking remains important for assessing the effectiveness of circulation. Palpating the brachial, carotid, or femoral pulse is equally effective.

Assessment of tidal breathing parameters in infants with cystic fibrosis.

Simple methods are needed to assess lung function in infants with cystic fibrosis (CF). This study determined the relationship between simple measurements obtained from tidal breathing with those from more complicated forced expiratory manoeuvres. Healthy infants and infants with CF were recruited from two maternity units and five specialist CF hospitals, respectively. Respiratory rate, tidal volume, minute ventilation and the tidal breathing ratio (TPTEF:TE) were measured in sedated infants and compared with forced expiratory volume in 0.4 seconds (FEV0.4) measured by the raised volume technique. Altogether, 95 healthy infants and 47 infants with CF of similar age, sex, ethnicity and proportion exposed to maternal smoking were recruited. There was no difference in TPTEF:TE and tidal volume between healthy infants and those with CF. Minute ventilation was significantly greater in infants with CF due to a mean (95% confidence interval) increase in respiratory rate of 5.8 (3.2-8.4) min(-1). Thirteen (28%) infants with CF had a respiratory rate elevated by >2 SD. However, no association between respiratory rate and FEV0.4 could be identified. Tidal breathing ratio was not useful in identifying diminished airway function in infants with cystic fibrosis. An elevated respiratory rate may be due in part to ventilation heterogeneity but is poorly predictive of diminished airway function measured by forced expiration.

Assessment of exhaled nitric oxide kinetics in healthy infants.

Exhaled nitric oxide (Fe(NO)) measurements provide a noninvasive approach to the evaluation of airway inflammation. Flow-independent NO exchange parameters [airway NO transfer factor (D(NO)) and airway wall NO concentration (Cw(NO))] can be estimated from Fe(NO) measurements at low flows and may elucidate mechanisms of disturbances in NO exchange. We measured Fe(NO) in sedated infants by using an adaptation of a raised lung volume rapid thoracic compression technique that creates forced expiration through a mass-flow controller that lasts 5-10 s, at a constant preset flow. We measured Fe(NO) at expired flows of 50, 25, and 15 ml/s in five healthy infants (7-31 mo). Median Fe(NO) increased [24, 40, and 60 parts per billion (ppb)] with decreasing expiratory flows (50, 25, and 15 ml/s). Group median (range) for D(NO) and Cw(NO) were 12.7 (3.2-37) x 10(-3) nl. s(-1). ppb(-1) and 108.9 (49-385) ppb, respectively, similar to values reported in healthy adults. Exhaled NO is flow dependent; flow-independent parameters of exhaled NO kinetics can be assessed in infants and are similar to values described in adults.

Functional MRI of visual cortex in sedated 18 month-old infants with or without periventricular leukomalacia.

Functional MRI (fMRI) of the visual cortex was evaluated in 42 sedated 18-month-old infants (mean corrected age; 31 males, 11 females) with or without periventricular leukomalacia (PVL). Data from 14 infants could not be evaluated because of movement artefacts. Ten of the remaining 28 infants showed no significant fMRI response upon visual stimulation. In 18 infants, a significant signal change upon stimulation was found in the visual cortex: in 17 a signal decrease and in one a signal increase. Functional changes were located mainly in the anterior part of the visual cortex. Seven of the 28 infants had normal MRI and 21 showed variable occipital PVL. An fMRI response was equally frequent in infants without PVL (4 of 7 infants) and with PVL (14 of 21 infants). In conclusion, fMRI was shown to be feasible in sedated infants. No correlation was found between functional activation and the presence or absence of occipital PVL. Type of fMRI response (signal decrease) and localization (anterior part of the visual cortex) are different from those seen in adults, probably reflecting a combination of sedation effects and immaturity of the visual system. At present, fMRI is a highly promising research tool; its clinical relevance still has to be established.