Making respiratory care safe for neonatal and paediatric intensive care unit staff: mitigation strategies and use of filters.

Background: Many medical devices in pediatric and newborn intensive care units can potentially expose healthcare workers (HCWs) and others to transmission of respiratory and other viruses and bacteria. Such fomites include ventilators, nebulizers, and monitoring equipment. Approach: We report the general, novel approach we have taken to identify and mitigate these risks and to protect HCWs, visitors and patients from exposure while maintaining the optimal performance of such respiratory equipment. Findings: The approach combined a high level of personal protective equipment (PPE), strict hand hygiene, air filtration and air conditioning and other relevant viral risk mitigation guidelines. This report describes the experiences from the SARS-CoV-2 pandemic to provide a reference framework that can be applied generally. The steps we took consisted of auditing our equipment and processes to identify risk through sources of potentially contaminated gas that may contain aerosolized virus, seeking advice and liaising with suppliers/manufacturers, devising mitigation strategies using indirect and direct approaches (largely filtering), performing tests on equipment to verify proper function and the absence of negative impacts and the development and implementation of relevant procedures and practices. We had a multidisciplinary team to guide the process. We monitored daily for hospital-acquired infections among staff caring for SARS-CoV-2 patients. Conclusion: Our approach was successful as we have continued to offer optimal intensive care to our patients, and we did not find any healthcare worker who was infected through the course of caring for patients at the bedside. The lessons learnt will be of benefit to future local outbreaks or pandemics.

Promoting Scientific Exchange and Student Training Through Scientific Meetings; Insights from a Joint Virtual Undergraduate Neuroscience Conference During the COVID-19 Pandemic.

Participation in scientific conferences is a fundamental part of neuroscience and student training. Many conference opportunities have been cancelled, limited, or changed in response to the COVID-19 pandemic. This paper is a conference report from a joint virtual 2021 meeting of two regional undergraduate neuroscience conferences, the Midwest/Great Lakes Undergraduate Research Symposium in Neuroscience (mGluRs) and the Midwest Regional Neuroscience Conference (MidBrains). We discuss our conference planning logistics, benefits and challenges of the virtual conference format, student feedback on the virtual meeting, additional benefits of a joint meeting, and "take home" messages and considerations for future conferences. We hope insights from our experience can benefit future conference organizers in planning scientific conferences, both for in-person and virtual settings.

The first late cretaceous mawsoniid coelacanth (Sarcopterygii: Actinistia) from North America: Evidence of a lineage of extinct 'living fossils'.

Today, the only living genus of coelacanth, Latimeria is represented by two species along the eastern coast of Africa and in Indonesia. This sarcopterygian fish is nicknamed a "living fossil", in particular because of its slow evolution. The large geographical distribution of Latimeria may be a reason for the great resilience to extinction of this lineage, but the lack of fossil records for this genus prevents us from testing this hypothesis. Here we describe isolated bones (right angular, incomplete basisphenoid, fragments of parasphenoid and pterygoid) found in the Cenomanian Woodbine Formation in northeast Texas that are referred to the mawsoniid coelacanth Mawsonia sp. In order to assess the impact of this discovery on the alleged characteristic of "living fossils" in general and of coelacanths in particular: 1) we compared the average time duration of genera of ray-finned fish and coelacanth in the fossil record; 2) we compared the biogeographic signal from Mawsonia with the signal from the rest of the vertebrate assemblage of the Woodbine formation; and 3) we compared these life traits with those of Latimeria. The stratigraphical range of Mawsonia is at least 50 million years. Since Mawsonia was a fresh, brackish water fish with probably a low ability to cross large sea barriers and because most of the continental components of the Woodbine Fm vertebrate assemblage exhibit Laurasian affinities, it is proposed that the Mawsonia's occurrence in North America is more likely the result of a vicariant event linked to the break-up of Pangea rather than the result of a dispersal from Gondwana. The link between a wide geographic distribution and the resilience to extinction demonstrated here for Mawsonia is a clue that a similar situation existed for Latimeria, which allowed this genus to live for tens of millions of years.

Delivery of Inhaled Nitric Oxide During MRI to Ventilated Neonates and Infants.

BACKGROUND: Many pediatric and neonatal ICU patients receive nitric oxide (NO), with some also requiring magnetic resonance imaging (MRI) scans. MRI-compatible NO delivery devices are not always available. We describe and bench test a method of delivering NO during MRI using standard equipment in which a NO delivery device was positioned in the MRI control room with the NO blender component connected to oxygen and set to 80 ppm and delivering flow via 12 m of tubing to a MRI-compatible ventilator, set up inside the MRI scanner magnet room. METHODS: For our bench test, the ventilator was set up normally and connected to an infant test lung to simulate several patients of differing weight (ie, 4 kg, 10 kg, 20 kg). The NO blender delivered flows of 2-10 L/min to the ventilator to achieve a range of NO and oxygen concentrations monitored via extended tubing. The measured values were compared to calculated values. RESULTS: A range of NO concentrations (12-41 ppm) and FIO2 values (0.67-0.97) were achieved during the bench testing. The additional flow increased delivered peak inspiratory pressure and PEEP by 1-5 cm H2O. Calculated values were within acceptable ranges and were used to create a lookup table. CONCLUSIONS: In clinical use, this system can safely generate a range of NO flows of 15-42 ppm with an accompanying FIO2 range of 0.34-0.98.

Characterizing the Undergraduate Neuroscience Major in the U.S.: An Examination of Course Requirements and Institution-Program Associations.

Neuroscience is a rapidly expanding field, and many colleges and universities throughout the country are implementing new neuroscience degree programs. Despite the field's growth and popularity, little data exists on the structural character of current undergraduate neuroscience programs. We collected and examined comprehensive data on existing undergraduate neuroscience programs, including academic major requirements and institution characteristics such as size, financial resources, and research opportunities. Thirty-one variables covering information about course requirements, department characteristics, financial resources, and institution characteristics were collected from 118 colleges and universities in the United States that offer a major titled "neuroscience" or "neural sciences." Data was collected from publicly available sources (online databases, institutions' neuroscience program websites) and then analyzed to define the average curriculum and identify associations between institution and program characteristics. Our results suggest that the average undergraduate neuroscience major requires 3 chemistry, 3 biology, 3 laboratory, 2-3 neuroscience, 1 physics, 1 math, and 2 psychology courses, suggesting that most neuroscience programs emphasize the natural sciences over the social sciences. Additionally, while 98% of institutions in our database offer research opportunities, only 31% required majors to perform research. Of note, 70% of institutions offering a neuroscience major do not have a neuroscience department, suggesting that most institutions offer neuroscience as an interdisciplinary major spanning several departments. Finally, smaller liberal arts colleges account for the majority of institutions offering a neuroscience major. Overall, these findings may be useful for informing groups interested in undergraduate neuroscience training, including institutions looking to improve or establish programs, students wanting to major in neuroscience and employers hiring neuroscience graduates.

Learning Experimental Design through Targeted Student-Centric Journal Club with Screencasting.

Knowledge and application of experimental design principles are essential components of scientific methodology, and experience with these skills is fundamental for participating in scientific research. However, undergraduates often enter the research laboratory with little training in designing and interpreting their own experiments. In the context of a research university laboratory, we designed a journal club training exercise to address this need. Students were instructed on methods for interpreting scientific literature using a screencast, a digital recording of a slide presentation narrated by an instructor. Students subsequently examined a series of research publications with a focus on the experimental designs and data interpretation in a two-session group discussion journal club format. We have found this approach to be an efficient and productive method for engaging students in learning about principles of experimental design and further preparing them for success in laboratory research.

Validation of Protein Knockout in Mutant Zebrafish Lines Using In Vitro Translation Assays.

Advances in genome-editing technology have made creation of zebrafish mutant lines accessible to the community. Experimental validation of protein knockout is a critical step in verifying null mutants, but this can be a difficult task. Absence of protein can be confirmed by Western blotting; however, this approach requires target-specific antibodies that are generally not available for zebrafish proteins. We address this issue using in vitro translation assays, a fast and standard procedure that can be easily implemented.

The microRNA network is altered in anterior cingulate cortex of patients with unipolar and bipolar depression.

MicroRNAs (miRNAs) are small, non-coding RNAs acting as post-transcriptional regulators of gene expression. Though implicated in multiple CNS disorders, miRNAs have not been examined in any psychiatric disease state in anterior cingulate cortex (AnCg), a brain region centrally involved in regulating mood. We performed qPCR analyses of 29 miRNAs previously implicated in psychiatric illness (major depressive disorder (MDD), bipolar disorder (BP) and/or schizophrenia (SZ)) in AnCg of patients with MDD and BP versus controls. miR-132, miR-133a and miR-212 were initially identified as differentially expressed in BP, miR-184 in MDD and miR-34a in both MDD and BP (although none survived multiple correction testing and must be considered preliminary). In silico target prediction algorithms identified putative targets of differentially expressed miRNAs. Nuclear Co-Activator 1 (NCOA1), Nuclear Co-Repressor 2 (NCOR2) and Phosphodiesterase 4B (PDE4B) were selected based upon predicted targeting by miR-34a (with NCOR2 and PDE4B both targeted by miR-184) and published relevance to psychiatric illness. Luciferase assays identified PDE4B as a target of miR-34a and miR-184, while NCOA1 and NCOR2 were targeted by miR-34a and 184, respectively. qPCR analyses were performed to determine whether changes in miRNA levels correlated with mRNA levels of validated targets. NCOA1 showed an inverse correlation with miR-34a in BP, while NCOR2 demonstrated a positive correlation. In sum, this is the first study to demonstrate miRNA changes in AnCg in psychiatric illness and validate miR-34a as differentially expressed in CNS in MDD. These findings support a mechanistic role for miRNAs in the regulation of stress-responsive genes disrupted in psychiatric illness.

Cerebrovascular Pressure Reactivity in Children With Traumatic Brain Injury.

OBJECTIVE: Traumatic brain injury is a significant cause of morbidity and mortality in children. Cerebral autoregulation disturbance after traumatic brain injury is associated with worse outcome. Pressure reactivity is a fundamental component of cerebral autoregulation that can be estimated using the pressure-reactivity index, a correlation between slow arterial blood pressure, and intracranial pressure fluctuations. Pressure-reactivity index has shown prognostic value in adult traumatic brain injury, with one study confirming this in children. Pressure-reactivity index can identify a cerebral perfusion pressure range within which pressure reactivity is optimal. An increasing difference between optimal cerebral perfusion pressure and cerebral perfusion pressure is associated with worse outcome in adult traumatic brain injury; however, this has not been investigated in children. Our objective was to study pressure-reactivity index and optimal cerebral perfusion pressure in pediatric traumatic brain injury, including associations with outcome, age, and cerebral perfusion pressure. DESIGN: Prospective observational study. SETTING: ICU, Royal Children's Hospital, Melbourne, Australia. PATIENTS: Patients with traumatic brain injury who are 6 months to 16 years old, are admitted to the ICU, and require arterial blood pressure and intracranial pressure monitoring. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Arterial blood pressure, intracranial pressure, and end-tidal CO2 were recorded electronically until ICU discharge or monitoring cessation. Pressure-reactivity index and optimal cerebral perfusion pressure were computed according to previously published methods. Clinical data were collected from electronic medical records. Outcome was assessed 6 months post discharge using the modified Glasgow Outcome Score. Thirty-six patients were monitored, with 30 available for follow-up. Pressure-reactivity index correlated with modified Glasgow Outcome Score (Spearman ρ = 0.42; p = 0.023) and was higher in patients with unfavorable outcome (0.23 vs -0.09; p = 0.0009). A plot of pressure-reactivity index averaged within 5 mm Hg cerebral perfusion pressure bins showed a U-shape, reaffirming the concept of cerebral perfusion pressure optimization in children. Optimal cerebral perfusion pressure increased with age (ρ = 0.40; p = 0.02). Both the duration and magnitude of negative deviations in the difference between cerebral perfusion pressure and optimal cerebral perfusion pressure were associated with unfavorable outcome. CONCLUSIONS: In pediatric patients with traumatic brain injury, pressure-reactivity index has prognostic value and can identify cerebral perfusion pressure targets that may differ from treatment protocols. Our results suggest but do not confirm that cerebral perfusion pressure targeting using pressure-reactivity index as a guide may positively impact on outcome. This question should be addressed by a prospective clinical study.

Basal microRNA expression patterns in reward circuitry of selectively bred high-responder and low-responder rats vary by brain region and genotype.

Mental health disorders involving altered reward, emotionality, and anxiety are thought to result from the interaction of individual predisposition (genetic factors) and personal experience (environmental factors), although the mechanisms that contribute to an individual's vulnerability to these disorders remain poorly understood. We used an animal model of individual variation [inbred high-responder/low-responder (bHR-bLR) rodents] known to vary in reward, anxiety, and emotional processing to examine neuroanatomical expression patterns of microRNAs (miRNAs). Laser capture microdissection was used to dissect the prelimbic cortex and the nucleus accumbens core and shell prior to analysis of basal miRNA expression in bHR and bLR male rats. These studies identified 187 miRNAs differentially expressed by genotype in at least one brain region, 10 of which were validated by qPCR. Four of these 10 qPCR-validated miRNAs demonstrated differential expression across multiple brain regions, and all miRNAs with validated differential expression between genotypes had lower expression in bHR animals compared with bLR animals. microRNA (miR)-484 and miR-128a expression differences between the prelimbic cortex of bHR and bLR animals were validated by semiquantitative in situ hybridization. miRNA expression analysis independent of genotype identified 101 miRNAs differentially expressed by brain region, seven of which validated by qPCR. Dnmt3a mRNA, a validated target of miR-29b, varied in a direction opposite that of miR-29b's differential expression between bHR and bLR animals. These data provide evidence that basal central nervous system miRNA expression varies in the bHR-bLR model, implicating microRNAs as potential epigenetic regulators of key neural circuits and individual differences associated with mental health disorders.

Acute and chronic glucocorticoid treatments regulate astrocyte-enriched mRNAs in multiple brain regions in vivo.

Previous studies have primarily interpreted gene expression regulation by glucocorticoids in the brain in terms of impact on neurons; however, less is known about the corresponding impact of glucocorticoids on glia and specifically astrocytes in vivo. Recent microarray experiments have identified glucocorticoid-sensitive mRNAs in primary astrocyte cell culture, including a number of mRNAs that have reported astrocyte-enriched expression patterns relative to other brain cell types. Here, we have tested whether elevations of glucocorticoids regulate a subset of these mRNAs in vivo following acute and chronic corticosterone exposure in adult mice. Acute corticosterone exposure was achieved by a single injection of 10 mg/kg corticosterone, and tissue samples were harvested 2 h post-injection. Chronic corticosterone exposure was achieved by administering 10 mg/mL corticosterone via drinking water for 2 weeks. Gene expression was then assessed in two brain regions associated with glucocorticoid action (prefrontal cortex and hippocampus) by qPCR and by in situ hybridization. The majority of measured mRNAs regulated by glucocorticoids in astrocytes in vitro were similarly regulated by acute and/or chronic glucocorticoid exposure in vivo. In addition, the expression levels for mRNAs regulated in at least one corticosterone exposure condition (acute/chronic) demonstrated moderate positive correlation between the two conditions by brain region. In situ hybridization analyses suggest that select mRNAs are regulated by chronic corticosterone exposure specifically in astroctyes based on (1) similar general expression patterns between corticosterone-treated and vehicle-treated animals and (2) similar expression patterns to the pan-astrocyte marker Aldh1l1. Our findings demonstrate that glucocorticoids regulate astrocyte-enriched mRNAs in vivo and suggest that glucocorticoids regulate gene expression in the brain in a cell type-dependent fashion.

Glucocorticoid treatment of astrocytes results in temporally dynamic transcriptome regulation and astrocyte-enriched mRNA changes in vitro.

While general effects of glucocorticoids are well established, the specific cellular mechanisms by which these hormones exert tissue-dependent effects continue to be elaborated. Diseases that demonstrate altered glucocorticoid signaling have been associated with alterations in astrocytes, yet relatively little is known about the effects of glucocorticoids upon this cell type. We have analyzed mRNA expression patterns following glucocorticoid treatment of mouse primary astrocyte cultures. Microarray analysis of cortical astrocyte cultures treated with dexamethasone over an eight-point, 24 h time course identified 854 unique genes with ≥twofold change in mRNA expression at one or more time points. Clustering analysis associated subsets of these mRNA expression changes with gene ontology categories known to be impacted by glucocorticoids. Numerous mRNAs regulated by dexamethasone were also regulated by the natural ligand corticosterone; all of the mRNAs regulated ≥twofold by corticosterone were substantially attenuated by cotreatment with the glucocorticoid receptor antagonist RU486. Of the mRNAs demonstrating ≥twofold expression change in response to both glucocorticoids, 33 mRNAs were previously associated with glucocorticoid regulation, and 36 mRNAs were novel glucocorticoid targets. All genes tested by qPCR for glucocorticoid regulation in cortical astrocyte cultures were also regulated by glucocorticoids in hippocampal astrocyte cultures (18/18). Interestingly, a portion of glucocorticoid-regulated genes were astrocyte enriched; the percentage of astrocyte-enriched genes per total number of regulated genes was highest for the early time points and steadily decreased over the time course. These findings suggest that astrocytes in vitro may initially deploy cell type-specific patterns of mRNA regulatory responses to glucocorticoids and subsequently activate additional cell type-independent responses.

External and internal biphasic direct current shock doses for pediatric ventricular fibrillation and pulseless ventricular tachycardia.

OBJECTIVE: To determine energy dose and number of biphasic direct current shocks for pediatric ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT). DESIGN: Observation of preshock and postshock rhythms, energy doses, and number of shocks. SETTING: Pediatric hospital. PATIENTS: Shockable ventricular dysrhythmias. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Forty-eight patients with VF or pulseless VT received external shock at 1.7 ± 0.8 (mean ± SD) J/kg. Return of spontaneous circulation (ROSC) occurred in 23 (48%) patients with 2.0 ± 1.0 J/kg, but 25 (52%) patients remained in VF after 1.5 ± 0.7 J/kg (p = .05). In 24 non-responding patients, additional 1-8 shocks (final dose, 2.8 ± 1.2 J/kg) achieved ROSC in 14 (58%) with 2.6 ± 1.1 J/kg but not in 10 (42%) with 3.2 ± 1.2 J/kg (not significant). Overall, 37 (77%) patients achieved ROSC with 2.2 ± 1.1 J/kg (range, 0.5-5.0 J/kg). Eight patients without ROSC recovered with cardiopulmonary bypass and internal direct current shock. At 13 subsequent episodes of VF or VT among eight patients, five achieved ROSC and survived. In combined first and subsequent resuscitative episodes, doses in the range of 2.5 to < 3 J/kg achieved most cases of ROSC. Survival for > 1 yr was seen in 28 (78%) of 36 patients with VF and seven (58%) of 11 patients with VT, with 35 (73%) overall. Lack of ROSC was associated with multiple shocks (p = .003). Repeated shocks with adhesive pads had significantly less impedance (p < .001). Pads in an anteroposterior position achieved highest ROSC rate. Internal shock for another 48 patients with VF or VT achieved ROSC in 28 (58%) patients with 0.7 ± 0.4 J/kg but not in 20 patients with 0.4 ± 0.3 J/kg (p = .01). Nineteen of the nonresponders who received additional internal 1-9 shocks at 0.6 ± 0.5 J/kg and one patient given extracorporeal membrane oxygenation all recovered, yielding 100% ROSC, but 1-yr survival tallied 43 (90%) patients. CONCLUSIONS: The initial biphasic direct current external shock dose of 2 J/kg for VF or pulseless VT is inadequate. Appropriate doses for initial and subsequent shocks seem to be in the range of 3-5 J/kg. Multiple shocks do not favor ROSC. The dose for internal shock is 0.6-0.7 J/kg.

Biphasic DC shock cardioverting doses for paediatric atrial dysrhythmias.

OBJECTIVE: To determine cardioversion doses of biphasic DC shock for paediatric atrial dysrhythmias. DESIGN: Prospective recording of energy, pre-shock and post-shock rhythms. SETTING: Paediatric hospital. PATIENTS: Shockable atrial dysrhythmias. MAIN RESULTS: Forty episodes of atrial dysrhythmias among 25 children (mean age 6.8+/-7.1 years, mean weight 28.2+/-28.5 kg) were treated with external shock. The first shock converted the dysrhythmia to sinus rhythm in 25 episodes. Cardioversion occurred in 2 of 8 (25%) episodes with a dose of <0.5 J/kg, 14 of 16 (88%) with a dose of 0.5-1.0 J/kg and 9 of 16 (56%) with a dose of >1.0 J/kg (p=0.01, Fisher's exact test). Ten of 15 initially non-responsive episodes were cardioverted with additional shocks at 1.1+/-0.6 J/kg (range 0.5-2.1 J/kg). Of the remaining 5 unresponsive episodes, 2 of ventricular fibrillation (induced by unsynchronized shock) were successfully defibrillated, and 3 were managed with cardiopulmonary bypass. Among 11 additional children (mean age 4.3+/-6.8 years, mean weight 18.1+/-22.0 kg), 18 episodes of atrial dysrhythmias were treated with internal shock which successfully cardioverted all episodes with one or more shocks at 0.4+/-0.2 J/kg. CONCLUSIONS: In rounded doses, recommended initial external cardioversion doses are 0.5-1.0 J/kg and subsequently up to 2 J/kg, internal cardioversion doses are 0.5 J/kg.

Analysis of messenger RNA expression by in situ hybridization using RNA probes synthesized via in vitro transcription.

The analysis of the spatial patterning of mRNA expression is critically important for assigning functional and physiological significance to a given gene product. Given the tens of thousands of mRNAs in the mammalian genome, a full assessment of individual gene functions would ideally be overlaid upon knowledge of the specific cell types expressing each mRNA. In situ hybridization approaches represent a molecular biological/histological method that can reveal cellular patterns of mRNA expression. Here, we present detailed procedures for the detection of specific mRNAs using radioactive RNA probes in tissue sections followed by autoradiographic detection. These methods allow for the specific and sensitive detection of spatial patterns of mRNA expression, thereby linking mRNA expression with cell type and function. Radioactive detection methods also facilitate semi-quantitative analyses of changes in mRNA gene expression.

A home respiratory support programme for children by parents and layperson carers.

AIM: To describe a respiratory support programme for children at home by parents and layperson carers. METHODS: Analysis of records of children with long-term mechanical respiratory support at home. RESULTS: From 1979 to 2008 the programme managed 168 children (median age 7 years, range 3 weeks-19 years) with obstructive sleep apnoea (55, 32%), neuromuscular conditions (42, 25%), tracheo-bronchomalacia (23, 14%), kyphoscoliosis-cerebral palsy (20, 12%), acquired central hypoventilation (8, 5%), congenital central hypoventilation (7, 4%), chronic lung disease or pulmonary hypoplasia (8, 5%), traumatic quadriplegia (3, 2%) and tumour-related quadriplegia (2, 1%). One hundred and sixty-one (96%) were discharged: 73 (46%) remain in the programme; 27 (16%) transferred to adult services, 25 (15%) recovered and 36 (23%) died. Principal modes of therapy were mask continuous positive airway pressure (CPAP) 35%, mask bilevel positive airway pressure 30%, tracheostomy CPAP 20%, tracheostomy mechanical ventilation 8%, phrenic nerve pacing 3%, negative pressure chamber ventilation 2% and nasal tube CPAP 2%. Two unexpected deaths occurred at home: one from accidental tracheostomy decannulation and another unrelated to respiratory support. Average time in the programme was 3.3 years. Parents of 69 children were provided with trained carers. Successful discharge resulted from early recognition of potential to discharge, parental training, recruitment and training of carers, purchase of equipment and secure funding. Seven children were not discharged, two of whom died in the hospital and five are subject to discharge planning. CONCLUSION: Respiratory support of children at home by trained parents and layperson carers is safe and efficient. All modes of respiratory support may be used.

Outcomes of surgical treatment of infants with hypoplastic left heart syndrome: an institutional experience 1983-2004.

AIM: To determine outcomes of surgical treatment of infants with hypoplastic left heart syndrome (HLHS). METHODS: Retrospective analysis of medical records of infants with HLHS. RESULTS: 129 of 206 (63%) infants with HLHS were managed surgically over the period 1983-2004. Survival from all stages of surgical repair was 52 (40%) patients with significantly different (P < 0.001) survival according to surgical techniques and post-operative intensive care management recognisable in three eras. During 1983-1995 a classical Norwood stage 1 operation with a systemic-pulmonary shunt was performed for 61 infants with 13 (21%) survivors. From 1996 to 2002, pulmonary vasoconstriction and systemic vasodilatation after stage 1 operation were used to optimise systemic blood flow yielding a survival of 22 of 46 (48%) infants. From 2002 to 2004 a ventricular-pulmonary conduit was used with survival of 17 of 22 (77%) infants. Survival at 1, 6, 12 months and at 5, 10 and 15 years was 65%, 53%, 48%, 38%, 38% and 25%, respectively. The mean +/- SD number of surgical procedures was 4.5 +/- 3.7; duration of hospitalisation 53 +/- 52 days (median 38); number of hospital admissions 3.0 +/- 3.5; duration in intensive care 18 +/- 20 days (median 11); hours of mechanical ventilation 278 +/- 398 (median 151). CONCLUSION: Short-term survival of HLHS has improved substantially over recent years with a ventricular-pulmonary conduit while long-term survival has been mediocre after arterial systemic-pulmonary shunts. Irrespective of type of primary surgery, infants undergo many operations and spend long periods in hospital and intensive care.

Probabilities of heart donors arising within specified times for child recipients.

AIM: To determine the availability of donor hearts for children of different blood group and weight needing urgent heart transplantation. METHODS: Data maintained by the Australia and New Zealand Organ Donor Registry 1989-2004 were analysed to determine the frequency of donation. Probabilities of suitable donor availability within 10, 20, 30, 40, 60, 90 and 180 days were estimated using a Poisson model with the assumptions that traditional ABO blood compatibilities applied, suitable donors were 0.8-4.0 times the recipient's body weight (BW) and suitable adult donors were aged <40 years. RESULTS: Probabilities of suitable donor availability increase with passage of time from 10 to 180 days and decrease with competition from other needful recipients. Maximum suitable donor availability occurs for children of all blood groups at body weight 20 kg. The probabilities of a donor heart arising within 40 days (maximum safe duration of extracorporeal membrane oxygenation support locally available for young children) for this recipient body weight according to blood group is 0.89, 0.85, 0.73, 0.67 (AB, A, B, O). Probabilities for recipients of BW 3 kg and 60 kg respectively are 0.16, 0.14, 0.10, 0.09 (AB, A, B, O) and 0.66, 0.61, 0.47, 0.42 (AB, A, B, O). CONCLUSION: Expectation of suitable heart donation arising within 40 days for needful recipients in Australia is low for infants (probability <0.3), moderate for small children (probability 0.5-0.9) and modest for large children (probability 0.4-0.7), with variation at all body weights according to blood group and waiting time.

Oxygen delivery using self-inflating resuscitation bags.

OBJECTIVE: Oxygen-filled self-inflating resuscitators are used by some as a source of oxygen for spontaneously breathing patients. In this application, the bag is not compressed and oxygen is assumed to flow freely from the patient outlet through a mask positioned loosely over the patient's face. We tested 11 resuscitators to determine the delivery of oxygen from the patient outlet using different inlet flows. DESIGN: Bench test. SETTING: A pediatric intensive care unit. INTERVENTIONS: Patient outlet flow was measured at inlet flows of 5, 10, and 15 L/min at two different orientations of the reservoir valve assembly (upright and inverted). MEASUREMENTS AND MAIN RESULTS: Patient outlet flow varied between resuscitators but was always less than the inlet flow and, in some cases, was as little as approximately 20% of the inlet flow. As the inlet flow rate was increased, the percentage of outlet flow that a patient received decreased, particularly in the upright position. At inlet flows of 5, 10, and 15 L/min, patient outlet flow ranged from 1.1 to 4.6 L/min, 1.6 to 5.1 L/min, and 2.0 to 6.5 L/min, respectively. CONCLUSIONS: Self-inflating resuscitators deliver a significantly lower flow of oxygen than the provided inlet flow and should not be relied on to deliver a precise amount of flow of oxygen to spontaneously breathing patients.

The effect of inlet gas temperatures on heated humidifier performance.

The aim of the current study was to determine the temperature range of gas at the point at which it passes into a heated humidifier within an intensive care unit and to experimentally examine the effect of different inlet gas temperatures on the performance of a heated humidifier. Various gas and ambient temperatures were measured in an intensive care unit and within ventilator circuits. Ventilator oxygen and air inlet temperatures, ventilator gas outlet temperatures, and humidifier gas inlet temperatures were measured in conjunction with the use of a number of ventilators. Ambient temperatures within the ward ranged from 22.8 degrees C to 28.9 degrees C, while typical ward humidifier gas inlet temperatures ranged from 24.3 degrees C to 28.8 degrees C. Humidity output from a heated humidifier was then determined in an experimental setup at controlled levels of inlet gas temperature using a constant gas flow. A decrease in humidity production, from approximately 36 mg/L at a humidifier inlet gas temperature of 18 degrees C, to 26 mg/L at a humidifier inlet gas temperature of 32 degrees C, was observed with increasing gas inlet temperature. We conclude that humidity output from a heated humidifier varies with inlet gas temperature, decreasing as inlet gas temperature increases. Inlet gas temperatures above 26 degrees C may result in inadequate humidification.