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We performed a prospective, randomized trial comparing ultrasound guidance of suprapubic bladder aspiration with unguided aspiration. The acquisition of urine improved with ultrasound guidance from 60% to 96.4%. The number of needle insertions decreased and the amount of urine obtained increased. Ultrasonography is a useful tool for bladder aspiration.

Introduction The Babylog VN500 ventilator (Draeger, Lubeck, Germany) in High frequency oscillation mode (HFOV) has the ability to control tidal volume (VThf) using a Volume Guarantee function. However, appropriate VThf values during this mode of ventilation has not been established. Aim The aim of this study was to establish normative data for VThf/kg during HFOV and explore its correlation with FiO 2 , day of life (DOL), gestational age (GA) and frequency (Freq). Methods Newborns admitted to the level III NICU from January 2012 till September 2013 treated with VN-500 in HFOV mode according to strict clinical protocol were included. Indications for HFOV were: PCO 2 > 65 on two consecutive blood gases and RR > 60. Blood gases with corresponding vent settings, time, patient’s weight and clinical diagnosis, were prospectively recorded. Measured VThf values were included only when PCO 2 was in the ‘normocapneic range’ of 40–55 torr. Univariate analysis for FiO 2 , DOL, GA and Freq as well as Spearman’s rank correlation coefficient was done. Results 37 patients were treated with rescue HFOV; BW = 875.9 g ± 163.7 and GA = 26.4 ± 1.4 (mean ± SD). 201 of 425 sets of blood gases met normocapnic criteria. The PCO 2 was 46.5 ± 3.7 mmHg and VThf/kg 2.00 ± 0.59 mL/kg (mean ± SD). Correlation with GA, DOL, FiO 2 and Freq are shown in the Table (*p Conclusions The mean VThf during normocapnia on HFOV is 2 mL/kg but its value is affected by GA, DOL, FiO 2 and Freq.

Background Weaning of mechanical ventilation (MV), assessment of extubation readiness and provision of post-extubation support are critical steps in the care of extremely preterm infants ( Objective Determine the peri-extubation practices used in extremely preterm infants internationally. Methods From Oct 2013 to Feb 2014 a structured questionnaire with 15 questions related to peri-extubation practices was circulated to the clinical directors of 162 neonatal intensive care units across Canada, USA, Ireland, Australia and New Zealand. Results 112 directors responded to the questionnaire (69%). The majority of units do not have written protocols for any aspect of MV (64%). The decision to extubate is generally made by the attending neonatologist (99%) or neonatal fellows (71%), based on ventilator settings, blood gases and haemodynamic stability; 16% of units extubate infants based on Spontaneous Breathing Trial (SBT). The SBT’s varied on definitions of failure and durations; from 10 min (35%). The majority of infants are extubated ≤3 days of life (76%) to nasal CPAP (84%). The failure rate was estimated to be 10–30%, but there was lack of consensus on the definition of failure (re-intubation within 24, 48 or 72 h after extubation). The decision to reintubate was almost always based on clinical judgement of physicians (88%), rather than well defined re-intubation criteria. Conclusions Peri-extubation practices in extremely preterm infants are not always evidence based and frequently physician-dependent. High quality trials are required to inform guidelines and standardise practices for this important aspect of neonatal intensive care.

Recently, synchronized modes of conventional mechanical ventilation became available for neonatal ventilatory support, but there has been little information regarding details of patient-ventilator interactions during pressure support, volume support, or any other volume-targeted modes of synchronized ventilation in newborn infants. Our objective was to obtain comparative data on patient-ventilator interactions and stability of delivered tidal volume (V(T)) for the different modes of synchronized mechanical ventilation in stable ventilated newborn infants. We examined the effects of pressure support ventilation (PSV) and volume guarantee (VG) modes of a prototype Drager Babylog ventilator on peak and mean airway pressures (PIP and Paw), inspiratory time (t(in)), and V(T) in 23 ventilated newborn infants. Twelve infants were studied while on assist/control (AC) and 11 on synchronized intermittent mandatory ventilation (SIMV). Mean birth weight was 1,650 +/- 1,180 g, gestational age 31 +/- 6 weeks, and age at time of study was 19 +/- 26 days. Data for 400-600 breaths from each infant were downloaded directly from the ventilator pressure and volume-monitoring module, and analyzed using ANOVA for repeated measures. Mean values and breath-to-breath variability were compared for 20-min periods of AC or SIMV followed by PSV, PSV+VG, and back to baseline AC or SIMV. PSV and PSV+VG led to shorter t(in) and thus to lower Paw, compared to AC. Mean PIP was similar across all AC modes but more variable during VG, reflecting the servocontrol of PIP. V(T) did not differ between AC modes, but was significantly less variable with VG added. PSV and PSV+VG led to lower and less variable PIP and Paw, compared to SIMV, because t(in) was shorter and every breath was supported in PSV and PSV+VG. V(T) was similar in SIMV, PSV, and PSV+VG, but less variable with PSV+VG. Arterial blood gas tensions were similar across all ventilation modes. We conclude that the ventilator prototype functioned as intended. Breath-to-breath tidal volume variability was significantly reduced in VG modes, although not completely eliminated.

Significant respiratory morbidity following elective cesarean delivery has been widely reported.1-4 More recently, it has been recognized that this morbidity is not always the result of inadvertent delivery of a premature neonate,5 but, instead, may be due to a predilection of these neonates for developing persistent pulmonary hypertension of the newborn(PPHN).6-8 Despite Heritage and Cunningham's report6 of 25% mortality in patients with persistent pulmonary hypertension following elective repeat cesarean section, the potential severity of respiratory distress associated with this method of delivery does not appear to be generally recognized. Extracorporeal membrane oxygenation (ECMO) is increasingly used to treat newborns

Objective To investigate the efficacy and safety of dorsal penile nerve block (DPNB) and eutectic mixture of lidocaine (EMLA) for palliation of pain associated with circumcision in low-birth-weight infants. Design Randomized, blinded, controlled trial. Setting Intensive care nursery (step down unit) at Georgetown University Medical Center, Washington, DC. Participants Fifty neonates with weights of 1600 to 2500 g at the time of circumcision who were discharged from the hospital between May 1994 and June 1995 were randomly assigned to the DPNB, EMLA, or control group. Twenty-five infants who were otherwise eligible were excluded because of parental refusal of consent to participate. Interventions Infants in the DPNB and EMLA groups received anesthesia with subcutaneous injection of 1% lidocaine hydrochloride or topical EMLA, respectively. The control group received sham anesthesia with topical placebo (acid mantle cream). Main Outcome Measures Changes in physiologic variables (heart rate, blood pressure, oxygen saturation, and respiratory rate) and behavioral score 20 minutes before, during, and 5 and 20 minutes after circumcision between DPNB and control groups. Surgical complications and adverse effects were also monitored. Results Fifty infants were enrolled in the study: 19 randomized to the DPNB group, 19 to the control group, and 12 to the EMLA group. Enrollment into the EMLA group was suspended early because of redness and blistering of the foreskin in 2 infants, and this entire group was excluded from further analysis. The clinical course was similar in all groups of infants. All circumcisions were performed without complication or technical difficulty. Statistically significant differences were noted in heart rate, respiratory rate, and behavioral score when comparing the DPNB group with controls during and after circumcision. Conclusion Dorsal penile nerve block is safe and effective in controlling pain associated with circumcision in low-birth-weight infants.

Objective. To test the hypothesis that high-frequency jet ventilation (HFJV) will reduce the incidence and/or severity of bronchopulmonary dysplasia (BPD) and acute airleak in premature infants who, despite surfactant administration, require mechanical ventilation for respiratory distress syndrome.Design. Multicenter, randomized, controlled clinical trial of HFJV and conventional ventilation (CV). Patients were to remain on assigned therapy for 14 days or until extubation, whichever came first. Crossover from CV to HFJV was allowed if bilateral pulmonary interstitial emphysema or bronchopleural fistula developed. Patients could cross over to the other ventilatory mode if failure criteria were met. The optimal lung volume strategy was mandated for HFJV by protocol to provide alveolar recruitment and optimize lung volume and ventilation/perfusion matching, while minimizing pressure amplitude and O2 requirements. CV management was not controlled by protocol.Setting. Eight tertiary neonatal intensive care units.Patients. Preterm infants with birth weights between 700 and 1500 g and gestational age 0.30 at 2 to 12 hours after surfactant administration, received surfactant by 8 hours of age, were Outcome Measures. Primary outcome variables were BPD at 28 days and 36 weeks of postconceptional age. Secondary outcome variables were survival, gas exchange, airway pressures, airleak, intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and other nonpulmonary complications.Results. A total of 130 patients were included in the final analysis; 65 were randomized to HFJV and 65 to CV. The groups were of comparable birth weight, gestational age, severity of illness, postnatal age, and other demographics. The incidence of BPD at 36 weeks of postconceptional age was significantly lower in babies randomized to HFJV compared with CV (20.0% vs 40.4%). The need for home oxygen was also significantly lower in infants receiving HFJV compared with CV (5.5% vs 23.1%). Survival, incidence of BPD at 28 days, retinopathy of prematurity, airleak, pulmonary hemorrhage, grade I–II IVH, and other complications were similar. In retrospect, it was noted that the traditional HFJV strategy emphasizing low airway pressures (HF-LO) rather than the prescribed optimal volume strategy (HF-OPT) was used in 29/65 HFJV infants. This presented a unique opportunity to examine the effects of different HFJV strategies on gas exchange, airway pressures, and outcomes. HF-OPT was defined as increase in positive end-expiratory pressure (PEEP) by ≥1 cm H2O from pre-HFJV baseline and/or use of PEEP of ≥7 cm H2O. Severe neuroimaging abnormalities (PVL and/or grade III–IV IVH) were not different between the CV and HFJV infants. However, there was a significantly lower incidence of severe IVH/PVL in HFJV infants treated with HF-OPT compared with CV and HF-LO. Oxygenation was similar between CV and HFJV groups as a whole, but HF-OPT infants had better oxygenation compared with the other two groups. There were no differences in Paco2 between CV and HFJV, but the Paco2 was lower for HF-LO compared with the other two groups. The peak inspiratory pressure and ΔP (peak inspiratory pressure-PEEP) were lower for HFJV infants compared with CV infants.Conclusions. HFJV reduces the incidence of BPD at 36 weeks and the need for home oxygen in premature infants with uncomplicated RDS, but does not reduce the risk of acute airleak. There is no increase in adverse outcomes compared with CV. HF-OPT improves oxygenation, decreases exposure to hypocarbia, and reduces the risk of grade III–IV IVH and/or PVL.

AIMS—To compare the effects of a single dose of frusemide administered either intravenously or by nebulisation on pulmonary mechanics in premature infants with evolving chronic lung disease. METHODS—The effect of frusemide on pulmonary mechanics was studied at a median postnatal age of 23 (range 14-52) days in 19 premature infants at 24 to 30 weeks gestational age, who had been dependent on mechanical ventilation since birth. Frusemide (1 mg/kg/body weight) was administered, in random order, intravenously and by nebulisation, on two separate occasions 24 hours apart. Pulmonary function studies were performed before and at 30, 60, and 120 minutes after administration of frusemide. Urine was collected for six hours immediately before and for six hours after administration of frusemide. RESULTS—Nebulised frusemide increased the tidal volume 31(SE 11.5)% and compliance 34 (SE 12)% after two hours, whereas no change in either was noted for up to two hours after intravenous frusemide administration. Neither intravenous nor nebulised frusemide had any effect on airway resistance. Six hour urine output increased from a mean (SE) of 3.3 (0.4) ml/kg/hour to 5.9 (0.8) ml/kg/hour following intravenous frusemide administration while nebulised frusemide had no effect on urine output. Urinary sodium, potassium, and chloride losses were also significantly higher after intravenous frusemide, whereas nebulised frusemide did not increase urinary electrolyte losses. CONCLUSION—Single dose nebulised frusemide improves pulmonary function in premature infants with evolving chronic lung disease without adverse effects on fluid and electrolyte balance. Keywords: inhaled frusemide; pulmonary mechanics; chronic lung disease of prematurity

Introduction PPHN is treated with inhaled nitric oxide (iNO). A novel ventilator circuit connector (NVCC, AFECTAIR®, Discovery Laboratories, Inc., Warrington, PA) has been developed to simplify the delivery of aerosols to patients receiving ventilatory support. We hypothesized that use of the NVCC for iNO delivery would substantially reduce NO consumption. Aim To compare the NVCC with the SoC in the delivery of iNO under simulated neonatal ventilator conditions. Material and Methods A pediatric/neonatal test system with Babylog® VN-500 with various inspiratory pressures, test lung, and ASL-5000 lung simulator were used. For SoC measurements, using a standard wye connector, the iNO was delivered per the manufacturer’s instructions. With the NVCC, iNO was administered by introducing the NO via a tube attached directly to the NVCC. NO concentrations were measured with a NOxBOX®+ analyzer and NO flow was recorded by Electronic Nitric Oxide flow controller abd titrated to 20 ppm at the patient interface. Results Compared with SoC, there was a 2 to 3 fold decrease in NO flow requirements to achieve desired iNO concentration with the NVCC. The delivery of O2 was not different between the study conditions. NO2 levels were slightly higher for the NVCC group, but never higher than 1.13 ppm. Conclusion The NVCC significantly decreased the NO flow required for targeted delivery of 20 ppm. The NVCC allows for simplified therapeutic gas delivery with reduced NO utilization. These results warrant further study of NVCC on compatibility assessment with various modes of ventilation and delivery of other medical gases.

The treatment of neonates with persistent pulmonary hypertension of the newborn (PPHN) is controversial with no consensus on diagnostic criteria or treatments. Hyperventilation has been the therapeutic mainstay. However, two widely variant alternative approaches have been proposed: ventilation without induced alkalosis, or more aggressive therapies such as high frequency ventilation or extracorporeal membrane oxygenation. We wished to determine the extent to which these alternative treatments have diffused into practice.A forced choice questionnaire was mailed to a sample representing 10% of 3740 practicing neonatologists. Sixty percent of those surveyed responded. Data on treatment practices was tabulated. Subanalyses with respect to training era, practice site, and geographic region were performed.In patients with meconium aspiration syndrome, without evidence of PPHN, 36% described their initial management as hyperventilation. If PPHN was confirmed, hyperventilation was used in 90% of patients by 44% of the respondents. Muscular paralysis and inotropic support were also used frequently. Alkali and vasodilator infusion were used less frequently. The gentle ventilation strategy proposed by Wung and James at Columbia Babies Hospital was used infrequently by 47% of respondents. Gentle ventilation was used more frequently by board-certified neonatologists than those not certified. No significant differences in practice were identified by geographic region or era of training. When standard treatment failed, only 40% of the respondents utilized rescue treatments such as high frequency ventilation or extracorporeal membrane oxygenation.This study documents that gentle ventilation, an easily and inexpensively adopted innovation, has not diffused into practice significantly while more expensive high technology treatments, such as high frequency ventilation and extracorporeal membrane oxygenation, have penetrated more significantly.

See article by Boels et al. [3] (pages 140–150) in this issue. During transition to the extrauterine environment, the newborn infant must accomplish complex cardiorespiratory adjustments. Dramatic changes in pulmonary and systemic vascular resistance must occur within minutes, followed by more gradual changes over the succeeding days. A host of mediators of vascular tone are involved in these processes and these have been the focus of extensive study. Differential responses from different vascular beds contribute to these circulatory changes; a variety of exogenous and endogenous factors affect the responsiveness of vascular beds to vasoactive mediators. When these critical circulatory changes are not accomplished successfully, the life-threatening disorder known as persistent pulmonary hypertension of the newborn may result [1]. In older subjects, pulmonary hypertension associated with the acute respiratory distress syndrome, congenital heart disease with left-to-right shunt, and primary pulmonary hypertension remain baffling challenges for … *Corresponding author. Tel.: +1-202-687-8569; fax: +1-202-784-4747

Volume Targetted Mechanical Ventilation of Newborns Maintains More Stable Tidal Volume but Does Not Prevent Hypocarbia in the First 24 Hours of Life

We examined the effects of Pressure Support (PS) and Volume Guarantee (VG) modes of a prototype Drager Babylog ventilator on peak and mean airway pressures (PIP & Paw), inspiratory time (Tin) and tidal volume (TV) in 12 ventilated newborn infants (mean birth weight 1720±1280 g, gest. age 30.5±5.8 wk, age at time of study 25.8±31.5 days). In PS each breath is supported as in Assist/Control (A/C) and is terminated when inspiratory flow declines to 15% of baseline. In VG the device regulates PIP to achieve a preset TV. Data for 200-600 breaths were downloded directly from the ventilator pressure and volume monitoring module using proprietary software (Lufu 3, Drager, Lubeck) and analyzed using ABstat statistical software. Mean values and breath to breath variability (mean SD) were compared for 20 minute periods of A/C or synchronized intermittent mandatory ventilation (SIMV) followed by PS, PS with VG and back to baseline: A/C-PS-PS+VG-AC (n=6) or SIMV-PS-PS+VG-SIMV (n=6) using ANOVA for repeated measures. PS and PS+VG led to shorter Tin (reflecting breath termination) and thus to lower Paw, compared to A/C. Mean PIP was similar in PS+VG compared to the other modes but more variable, reflecting the servocontrol of PIP. TV did not differ between modes and tended to be less variable in PS+VG. PS and PS+VG led to higher and less variable PIP and Paw, compared to SIMV because each breath is supported. TV was similar in SIMV, PS and PS+VG but less variable with PS and PS+VG, again reflecting support of all breaths in PS as opposed to SIMV. The ventilator prototype functioned as intended, though breath to breath tidal volume variability was not completely eliminated. Data expressed as mean± SD. + p

Perceived surplus of subspecialists may decrease the availability of subspecialty trainees. In Subspecialty areas such as Neonatal - Perinatal Medicine which traditionally involves a substantial clinical workload such decreases in workforce could adversely impact the educational experience of the trainees if fewer trainees were required to carry increased clinical responsibilities. A survey of Fellowship Directors was conducted by electronic mail and Fax to assess the current clinical workload of Fellows with particular attention to on-call schedules and to explore the attitudes of Program Directors toward the role of Fellows in patient care delivery. Responses were received from 41/65 programs (63%) that were successfully contacted. The mean number of Fellows per program was 4.5 (range 1-12). Contrary to expectations, the majority of programs anticipated no change in the number of Fellows in 1998. Current on-call frequency ranged from 1/3 to 1/8 nights in the first year (mean 1/4.9), 1/4 to 1/15 (mean 1/6.3) in year 2 and 1/4 to none in the third year (mean 1/6.6 in programs with on-call responsibility in year 3). Twenty-five programs do not allow Fellows to provide more than 24-36 hours of continuous coverage (such as covering an entire weekend) because of issues related to provider as well as patient safety, while 6 allow such coverage occasionally at the election of the Fellows. Seven programs do so routinely, but generally indicated that this is not in-house coverage. Only 4 of 41 programs (10%) planned to increase on-call frequency if the number of Fellows in the program were to decrease, with 31 programs indicating that attending physicians would take up the additional workload. Other solutions included hiring outside “moonlighters”, nurse practitioners or junior faculty to cover the on-call vacancies. However, 25/41 programs (61%) indicated that they would (or do already) allow their Fellows to provide additional on-call coverage for extra compensation(in-house moonlighting). A solid majority of Program Directors felt that Fellow availability should not affect their clinical workload in order to avoid adverse effects on the learning process. However, the widespread practice of additional compensated voluntary clinical duties (moonlighting) may have just such consequences. Limits should be placed on the amount of such voluntary activity because of the potential for conflict between monetary compensation and the educational process.

HIGH-FREQUENCY JET VENTILATION (HFJV) IN INFANTS WITH DECREASED CHEST WALL COMPLIANCE. 1526

Effect of breath termination criteria and endotracheal tube leak on tidal volume and inspiratory time in pressure support ventilation (PSV). 1525

COMPARISON OF TWO DIFFERENT DOSES OF NEBULIZED FUROSEMIDE ON PULMONARY FUNCTION IN INFANTS WITH CHRONIC LUNG DISEASE. 2060

We entered 142 infants with respiratory distress syndrome (RDS) in a randomized study of conventional (CV) vs high-frequency jet ventilation (HFJV) at 8 centers. Infants were eligible if they weighed 700-1500g and required mechanical ventilation with ≥30% O2 >2h after surfactant. The prescribed high-volume strategy (HI) was used in 34/69 HFJV patients; the rest were treated with standard HFJV strategy: low peak and mean pressure (LO). HI was defined as PEEP ≥ 7cmH2O or a ≥1cmH2O PEEP increase from baseline. Continuous variables are expressed as mean±SD. HFJV reduced the incidence of BPD at 36 wks post conceptional age. Unlike Wiswell, et al (AAP Meet. Oct 95), we did not see more adverse outcomes with HFJV. Major IVH/PVL were significantly more frequent in infants treated with LO (the strategy used by Wiswell, et al) than HI. Significantly lower PaCO2 in LO group suggests a possible mechanism. Table

We examined gas exchange and and airway pressures in 142 preemies entered in a randomized study of CV & HFJV at 8 centers. Infants were eligible if they were 700-1500g and required mechanical ventilation with ≥30% O2>2h after surfactant. The prescribed high-volume strategy defined as PEEP≥7cmH2O or a ≥1cmH2O PEEP increase from baseline (HI) was used in 34/69 HFJV patients; in 35 standard HFJV strategy of low peak and mean pressure was used (LO). Data were analyzed by ANOVA for repeat measures and are expressed as mean±SEM. PIP and delta p were lower with HFJV than CV(p

We reviewed records of 167 infants < 1500 g to identify risk factors and determine if changes in obstetrical and neonatal care from 1989 to 1995 affected the incidence of candida sepsis (CS). All available charts of infants who lived ≥ 7d were reviwed. Data were analyzed using chi square, t-test and multiple logistic regression. Mean birth weight (BW), gestational age (GA) and other demographics were similar in 1989-90 & 1994-95. Pneumothorax, necrotizing enterocolitis and severe IVH were less common in 1994-95, likely due to increased use of AS. Postnatal Abx use and feeding practices did not differ in the two epochs. Infants with CS were smaller (826±250 v. 1066±285g), more premature (25.9±2.3 v. 28.5 ±2.5wk), required longer ventilator support (36.4±27 v. 12.2 ±19d), received more Abx (35.3±18 v. 15.2±13d), had more CVLs 91% v. 50% for longer periods (26.5±19 v. 11.6±18d) and higher mortality (35% v. 9%) than those without CS (all p

Traditional lung management during extracorporeal membrane oxygenation (ECMO) calls for low inspiratory and expiratory pressures with low ventilator rate to achieve lung rest. However, rapid weaning of pressures to severely injured lungs commonly leads to marked increase in pulmonary opacification as seen on chest x-ray and loss of volume. We postulated that a sufficiently high level of PEEP could prevent this deterioration. Forty-six newborns, who required ECMO therapy for refractory respiratory failure, were maintained on 8 to 14 cm H2O PEEP. The peak pressure was 20 to 24 cm H2O, rate 10 to 15 breath/min, and FIO2 0.21. Forty-one (89%) of 46 patients survived to discharge. The duration of ECMO was significantly decreased compared to the national average (82.4 +/- 43 vs. 117.5 +/- 59 h). The lungs of most patients remained adequately expanded and free of severe pulmonary opacification. Eleven of 40 patients did show significant worsening of chest x-ray compared to baseline, but only one of 18 who were on PEEP of greater than or equal to 12 cm H2O showed such deterioration. No unexpected complications were encountered. These data suggest that the use of high PEEP during ECMO safely prevents deterioration of lung function and promotes more rapid lung recovery. PEEP levels of 12 to 14 cm H2O appear to be most effective.

From February 1985 through June 1987, 50 newborn infants in whom maximal ventilator therapy failed (80% predicted mortality) were treated with extracorporeal membrane oxygenation (ECMO) according to the following inclusion criteria: arterial oxygen tension less than 50 torr (alveolar-arterial oxygen gradient greater than 630 torr) for 2 hours or arterial oxygen tension less than 60 torr (alveolar-arterial oxygen gradient greater than 620 torr) for 8 hours. Criteria for exclusion from ECMO therapy included birth weight less than 2000 gm, gestational age less than 35 weeks, presence of intracranial hemorrhage, presence of other major congenital anomalies including cyanotic heart disease, and high levels of ventilatory support for more than 7 days. Mean birth weight was 3.28 +/- 0.56 kg, mean gestational age was 39.6 +/- 1.7 weeks, and mean age at the start of ECMO was 48.6 +/- 36.9 hours. Meconium aspiration, usually associated with persistent pulmonary hypertension, was the most common cause of pulmonary failure (62%). Mean pre-ECMO arterial oxygen tension during maximal ventilatory and pharmacologic support was 34.5 +/- 14.5 torr. Mean ventilatory support immediately before the institution of ECMO was as follows: peak inspiratory pressure 46.8 +/- 9.9 cm H2O, positive end-expiratory pressure 4.6 +/- 1.6 cm H2O, and intermittent mandatory ventilation rate 101.0 +/- 22.7 breaths/min with all patients receiving an inspired oxygen fraction of 1.0. Lung management to prevent pulmonary atelectasis during ECMO consisted of moderate levels of positive end-expiratory pressure (mean 10.3 +/- 2.6 cm H2O, range 8 to 14 in 94% of patients. Other mean ventilator parameters during ECMO were as follows: peak inspiratory pressure 22.8 +/- 1.6 cm H2O, intermittent mandatory ventilation rate 11.8 +/- 2.9, and inspired oxygen fraction 0.21. The overall long-term patient survival rate was 90%. Mean values for arterial blood gases and ventilator settings immediately after the discontinuation of ECMO were as follows: oxygen tension 78.4 +/- 22.1 torr, pH 7.39 +/- 0.10, carbon dioxide tension 37.4 +/- 10.7 torr, peak inspiratory pressure 25.2 +/- 3.9 cm H2O, positive end-expiratory pressure 5.6 +/- 1.2 cm H2O, and intermittent mandatory ventilation rate 41.3 +/- 12.6 with an inspired oxygen fraction of 0.42 +/- 0.17. Despite slightly higher levels of ventilator support (peak inspiratory pressure 46.8 versus 45.0 cm H2O, not significant) mean pre-ECMO oxygen tension was significantly lower than that reported from the National ECMO Registry (34.5 versus 42.0 torr, p less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

The microscopic appearance of lungs subjected to six hours of conventional ventilation (CV), standard high frequency jet ventilation (HFJV), and HFJV combined with low rate intermittent mandatory ventilation (CHFJV) was studied in 22 mongrel puppies. A lung injury model was created by insufflating 4 ml/kg of a 20% mixture of meconium into the trachea. The animals were initially ventilated at the same mean airway pressure (Paw). Subsequently, if PCO2 fell below 20 torr, peak and mean airway pressures were reduced. A scoring system was devised which assigned 0-3 points for each of eight lung injury parameters, and a total lung injury score (TLIS) was calculated. CHFJV resulted in significantly less bronchopneumonia and edema, when compared to CV. A consistent, though not significant, trend toward lesser injury scores in CHFJV animals was noted for several other parameters. Six of eight lungs exposed to CV had TLIS greater than 5 compared to only 1 of 9 ventilated by CHFJV. (P = 0.02). It is concluded that CHFJV may have a protective effect on the lung, perhaps because effective gas exchange is achieved with a lower pressure amplitude and at lower Paw.

To evaluate the effectiveness of high-frequency jet ventilation (HFJV) in the treatment of meconium aspiration, 28 puppies were assigned randomly to one of three ventilator techniques. After aspiration of 4 ml/kg of 20% meconium and baseline measurements on conventional ventilation (CV), the animals were ventilated for 6 h with either CV, HFJV, or HFJV combined with slow conventional ventilation (combined HFJV). Arterial and mixed venous blood gases, systemic and pulmonary arterial pressures, pulmonary capillary wedge pressure, and cardiac output were measured. Combined HFJV proved superior to the other two techniques, resulting in significantly better oxygenation and ventilation at a lower mean airway pressure (Paw). Oxygenation with standard HFJV was comparable to CV, producing Paw and PCO2 values intermediate between those of CV and combined HFJV. There were no significant intergroup differences in cardiac output or the incidence of pneumothorax. Improved gas exchange was attributed to alveolar recruitment and prevention of atelectasis. Alteration of the distribution and/or clearance of meconium may also be important.

An uncuffed pediatric version of the HI-LO JetTM triple lumen tube with an intramural jet channel for distal gas delivery was compared to a proximal delivery system (a metal cannula aimed at the ET tube orifice from a distance of 1-2mm to avoid obstructing the lumen). HI-LO tubes of 2.5, 3.0, 3.5, 4.0 & 5.0mm ID were tested in 5 anesthetized paralyzed cats using the MK-800 jet ventilator, duty cycle of 30%, FIO2 of 1.0, rates of 150 & 300 with normal & noncompliant lungs. The IDs of the metal cannula & the HI-LO tube jet channel were matched. Driving pressure was adjusted to maintain constant mean airway pressure for each pair. Under all conditions the two systems provided equally effective oxygenation & CO2 elimination: (Proximal - P, HI-LO - D). Both systems met the essential requirements of pediatric HFJV:sta bility & free expiratory channel. The HI-LO tube generated less entrainment.The pressure monitoring channel was useful & accurate.

Despite the increasing acceptance of high frequency jet ventilation (HFJV), very little work has been done to determine if lung damage results from its use. We performed an experimental study to compare the effects of conventional ventilation with those of HFJV on the lung parenchyma of anesthetized dogs. Thirteen animals were studied for periods ranging from 2-24 h. Using a double-lumen Carlen's endotracheal tube, each animals's lungs were ventilated simultaneously but independently, one with conventional ventilation, the other with HFJV. No gross or microscopic evidence of atelectasis or barotrauma was noted in either group. Less hyperaeration was seen in the majority of jet ventilated lungs compared to the conventionally ventilated. In no case did the jet ventilated side show more damage than the control. We concluded that it is possible to use HFJV for 24 h without apparent parenchymal lung damage. Reduced hyperaeration is identified as a possible advantage of HFJV over conventional methods.

To define limits of injector size/internal compressible volume (ICV) of the jet tubing in small subjects, we studied anesthetized paralyzed cats using the MK-800 jet ventilator & noncompliant tubing with ICV of 14 ml. FIO2 of 1.0 & 30% duty cycle remained constant. In part I the injector size was varied from #12,14,16 to 18 (2.16-1.06mm)at rates of 150 & 300/min with normal and noncompliant lungs. The driving pressure was adjusted to keep a constant mean airway pressure (MAP) for each set of conditions. In part II the ICV was ↑ from baseline(B) to 1.5B, 2B and 3B through the same sequence as in part I, using #14 & #16 injectors. Tracheal pressure tracing was recorded. Despite constant MAP, PCO2 rose with ↓ injector diameter though with normal lungs at 150/min PCO2 was normal even with the smallest injector (#18). Increasing ICV up to 3B had no effect with #14 injector or with normal lungs. With #16 injector and stiff lungs, PCO2 rose as ICV ↑.

• Shortly after birth, a 1,860-g premature male newborn with respiratory distress syndrome had brisk diuresis, rapid weight loss, and severe hyponatremia despite aggressive Na and fluid replacement. The serum cortisol level was normal, and the 17-OH progesterone concentration was low. He did not show any response to treatment with dexamethasone and desoxycorticosterone acetate. Results of renal function studies were within the normal range for his gestational age. The serum aldosterone level and plasma renin activity were grossly elevated, confirming the diagnosis of pseudohypoaldosteronism. This uniquely early and dramatic presentation was attributed to immaturity of the proximal renal tubule at 32 weeks' gestation. The subsequent improvement paralleled the rapid maturation of the kidney after birth. ( Am J Dis Child 1983;137:738-740)