Successful implementation of telehealth visits in the paediatric heart failure and heart transplant population

The Advanced Cardiac Therapies Improving Outcomes Network (ACTION) and Pediatric Heart Transplant Society (PHTS) convened a working group at the beginning of 2020 during the COVID-19 pandemic, with the aim of using telehealth as an alternative medium to provide quality care to a high-acuity paediatric population receiving advanced cardiac therapies. An algorithm was developed to determine appropriateness, educational handouts were developed for both patients and providers, and post-visit surveys were collected. Telehealth was found to be a viable modality for health care delivery in the paediatric heart failure and transplant population and has promising application in the continuity of follow-up, medication titration, and patient education/counselling domains.

Reducing donor acceptance practice variation - Learnings from a discussion forum

PURPOSE

Although waitlist mortality is unacceptably high, nearly half of donor heart offers are rejected by pediatric heart transplant centers. The Advanced Cardiac Therapy Improving Outcome Network (ACTION) and Pediatric Heart Transplant Society (PHTS) convened a multi-institutional donor decision discussion forum (DDDF) aimed at assessing donor acceptance practices and reducing practice variation.

METHODS

A 1-h-long virtual DDDF for providers across North America, the United Kingdom, and Brazil was held monthly. Each session typically included two case presentations posing a real-world donor decision challenge. Attendees were polled before the presenting center's decision was revealed. Group discussion followed, including a review of relevant literature and PHTS data. Metrics of participation, participant agreement with presenting center decisions, and impact on future decision-making were collected and analyzed.

RESULTS

Over 2 years, 41 cases were discussed. Approximately 50 clinicians attended each call. Risk factors influencing decision-making included donor quality (10), size discrepancy (8), and COVID-19 (8). Donor characteristics influenced 63% of decisions, recipient factors 35%. Participants agreed with the decision made by the presenting center only 49% of the time. Post-presentation discussion resulted in 25% of participants changing their original decision. Survey conducted reported that 50% respondents changed their donor acceptance practices.

CONCLUSION

DDDF identified significant variation in pediatric donor decision-making among centers. DDDF may be an effective format to reduce practice variation, provide education to decision-makers, and ultimately increase donor utilization.

Clinical Outcomes of SARS-CoV-2 Infection in Pediatric Patients on Ventricular Assist Device Support: An ACTION Registry Analysis

Adult patients on left ventricular assist device (LVAD) support have increased morbidity and mortality after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. There are no reported clinical data describing outcomes among pediatric patients on ventricular assist device (VAD) support infected with SARS-CoV-2. We conducted a retrospective study using the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) registry to evaluate patient characteristics and clinical outcomes after SARS-CoV-2 infection. A total of 22 children on VAD support (median age at infection 10.6 years) from 16 centers tested positive for SARS-CoV-2. Cardiomyopathy (59.1%) and congenital heart disease (40.9%) were the most common primary diagnoses. The type of support included LVAD in 19 (86.4%), biventricular assist device (BIVAD) in one (4.5%), and single ventricle VAD in two (9%) patients. At the time of infection, 50% were outpatients, 23% were inpatients on a general cardiology floor, and 27% were in the cardiac intensive care unit (CICU). Most patients (82%) were symptomatic at time of diagnosis, but only 13% required escalation of respiratory support, and 31% received SARS-CoV-2 therapies. Notably, no mortality occurred, and significant morbidity was rare after SARS-CoV-2 infection in pediatric patients on VAD support.

Deep learning of renal scans in children with antenatal hydronephrosis

INTRODUCTION

Antenatal hydronephrosis (ANH) is one of the most common anomalies identified on prenatal ultrasound, found in up to 4.5% of all pregnancies. Children with ANH are surveilled with repeated renal ultrasound and when there is high suspicion for a ureteropelvic junction obstruction on renal ultrasound, a mercaptuacetyltriglycerine (MAG3) Lasix renal scan is performed to evaluate for obstruction. However, the challenging interpretation of MAG3 renal scans places patients at risk of misdiagnosis.

OBJECTIVE

Our objective was to analyze MAG3 renal scans using machine learning to predict renal complications. We hypothesized that our deep learning model would extract features from MAG3 renal scans that can predict renal complications in children with ANH.

STUDY DESIGN

We performed a case-control study of MAG3 studies drawn from a population of children with ANH concerning for ureteropelvic junction obstruction evaluated at our institution from January 2009 until June of 2021. The outcome was renal complications that occur ≥6 months after an equivocal MAG-3 renal scan. We created two machine learning models: a deep learning model using the radiotracer concentration versus time data from the kidney of interest and a random forest model created using clinical data. The performance of the models was assessed using measures of diagnostic accuracy.

RESULTS

We identified 152 eligible patients with available images of which 62 were cases and 90 were controls. The deep learning model predicted future renal complications with an overall accuracy of 73% (95% confidence inteveral [CI] 68-76%) and an AUC of 0.78 (95% CI 0.7, 0.84). The random forest model had an accuracy of 62% (95% CI 60-66%) and an AUC of 0.67 (95% CI. 0 64, 0.72) DISCUSSION: Our deep learning model predicted patients at high risk of developing renal complications following an equivocal renal scan and discriminate those at low risk with moderately high accuracy (73%). The deep learning model outperformed the clinical model built from clinical features classically used by urologists for surgical decision making.

CONCLUSION

Our models have the potential to influence clinical decision making by providing supplemental analytical data from MAG3 scans that would not otherwise be available to urologists. Future multi-institutional retrospective and prospective trials are needed to validate our model.

Are biomechanics during gait associated with the structural disease onset and progression of lower limb osteoarthritis? A systematic review and meta-analysis

OBJECTIVE

To evaluate if gait biomechanics are associated with increased risk of structurally diagnosed disease onset or progression of lower limb osteoarthritis (OA).

METHOD

A systematic review of Medline and Embase was conducted from inception to July 2021. Two reviewers independently screened records, extracted data and assessed risk of bias. Included studies reported gait biomechanics at baseline, and either structural imaging or joint replacement occurrence in the lower limb at follow-up. The primary outcome was the Odds Ratio (OR) (95% confidence interval (CI)) of the association between biomechanics and structural OA outcomes with data pooled for meta-analysis.

RESULTS

Twenty-three studies reporting 25 different biomechanical metrics and 11 OA imaging outcomes were included (quality scores ranged 12-20/21). Twenty studies investigated knee OA progression; three studies investigated knee OA onset. Two studies investigated hip OA progression. 91% of studies reported a significant association between at least one biomechanical variable and OA onset or progression. There was an association between frontal plane biomechanics with medial tibiofemoral and hip OA progression and sagittal plane biomechanics with patellofemoral OA progression. Meta-analyses demonstrated increased odds of medial tibiofemoral OA progression with greater baseline peak knee adduction moment (KAM) (OR: 1.88 [95%CI: 1.08, 3.29]) and varus thrust presence (OR: 1.97 [95%CI: 1.32, 2.96]).

CONCLUSION

Evidence suggests that certain gait biomechanics are associated with an increased odds of OA onset and progression in the knee, and progression in the hip.

REGISTRATION NUMBER

PROSPERO CRD42019133920.

Faecal immunochemical testing in symptomatic patients to prioritize investigation: diagnostic accuracy from NICE FIT Study

BACKGROUND

This study investigated whether a quantitative faecal immunochemical test (FIT) could be used to select patients with either high- or low-risk symptoms of colorectal cancer for urgent investigation.

METHODS

A double-blinded diagnostic accuracy study was conducted in 50 hospitals in England between October 2017 and December 2019. Patients were eligible for inclusion if they had been referred to secondary care with suspected colorectal cancer symptoms meeting national criteria for urgent referral and triaged to investigation with colonoscopy.

RESULTS

The study included 9822 patients, of whom 7194 (73.2 per cent) had high-risk symptoms, 1994 (20.3 per cent) low-risk symptoms, and 634 (6.5 per cent) had other symptoms warranting urgent referral. In patients with high-risk symptoms, the sensitivity of FIT for colorectal cancer at cut-off values of 2 and 10 μg haemoglobin per g faeces was 97.7 (95 per cent c.i. 95.0 to 99.1) and 92.2 (88.2 to 95.2) per cent respectively, compared with 94.3 (84.3 to 98.8) and 86.8 (74.7 to 94.5) per cent in patients with low-risk symptoms at the same cut-off points. At cut-off values of 2, 10, and 150 μg/g, the positive predictive value for colorectal cancer was 8.9, 16.2, and 30.5 per cent respectively for those with high-risk symptoms, and 8.4, 16.9, and 35.5 per cent for those with low-risk symptoms.

CONCLUSION

FIT safely selects patients with high or low risk symptoms of colorectal cancer for investigation.

Ex vivo specimen MRI and pathology confirm a rectosigmoid mesenteric waist at the junction of the mesorectum and mesocolon

AIM

Continuity of the mesentery has recently been established and may provide an anatomical basis for optimal colorectal resectional surgery. Preliminary data from operative specimen measurements suggest there is a tapering in the mesentery of the distal sigmoid. A mesenteric waist in this area may be a risk factor for local recurrence of colorectal cancer. This study aimed to investigate the anatomical characteristics of the mesentery at the colorectal junction.

METHOD

In this cross-sectional study, 20 patients were recruited. After planned colorectal resection, the surgical specimens were scanned in a MRI system and subsequently dissected and photographed as per national pathology guidelines. Mesenteric surface area and linear measurements were compared between MRI and pathology to establish the presence and location of a mesenteric waist.

RESULTS

Specimen analysis confirmed that a narrowing in the mesenteric surface area was consistently apparent at the rectosigmoid junction. Above the anterior peritoneal reflection, the surface area and posterior distance of the mesentery of the upper rectum initially decreased before increasing as the mesentery of the sigmoid colon. These anatomical properties created the appearance of a mesenteric 'waist' at the rectosigmoid junction. Using the anterior reflection as a reference landmark, the rectosigmoid waist occurred at a mean height of 23.6 and 21.7 mm on MRI and pathology, respectively.

CONCLUSION

A rectosigmoid waist occurs at the junction of the mesorectum and mesocolon, and is a mesenteric landmark for the rectum that is present on both radiology and pathology.

The diagnostic accuracy of the faecal immunochemical test for colorectal cancer in risk-stratified symptomatic patients

INTRODUCTION

The faecal immunochemical test detects blood in the faeces, reporting faecal haemoglobin quantitatively in micrograms of haemoglobin per gram of faeces. The aim of this pilot study was to determine the feasibility of using the faecal immunochemical test as a rule-out test in symptomatic patients at low and high risk of colorectal cancer.

MATERIAL AND METHODS

Between November 2016 and October 2017, consecutive symptomatic patients within a multicultural part of London were recruited to perform a faecal immunochemical test prior to colonoscopy. Analysis was performed on the HM-JACKarc analyser.

RESULTS

Faecal immunochemical test samples were returned by 298 patients who underwent colonoscopy. There was no significant variation in faecal haemoglobin levels by age, sex, ethnicity or deprivation. The overall detection rate for colorectal cancer was 100% at 2 µg/g and 92% at 10 µg/g. If a faecal haemoglobin threshold for investigation of 2 µg/g (ie detectable) or 10 µg/g had been employed, the number of colonoscopies would have been reduced by 70% and 84%, respectively, in all symptomatic patients. For low-risk patients, the sensitivity of the faecal immunochemical test for colorectal cancer at both thresholds of 2 µg/g or 10 µg/g remained 100%, with the number of colonoscopies reduced by 80% and 91%, respectively.

CONCLUSION

This study shows that the faecal immunochemical test is a promising technology that detected colorectal cancer in all high- or low-risk symptomatic patients in our cohort at a threshold of detectable faecal haemoglobin. Data from adequately powered cohort studies will elucidate the true diagnostic accuracy of the test and the rate and patterns of undetected colorectal cancer.

Enhanced recovery after anterior resection: earlier leak diagnosis and low mortality in a case series

INTRODUCTION

Early detection and treatment of anastomotic leak may mitigate its consequences. Within an enhanced recovery setting, the subtle signs of a leak can be more apparent. There are multiple treatment options for anastomotic leak following anterior resection. This study aimed to determine when leaks are diagnosed in enhanced recovery, and whether the choice of intervention affects outcomes.

MATERIALS AND METHODS

We conducted a retrospective study of a prospectively maintained database of complications of anterior resections for rectal cancer in a district general hospital in the UK. Data were extracted on day of leak diagnosis, length of stay, intensive care admission, mortality and ileostomy reversal rate. Statistical analysis was performed using Student's t, Mann-Whitney U and chi square tests.

RESULTS

A total of 323 patients underwent anterior resection for colorectal cancer between 1 January 2007 and 1 October 2015. The leak rate was 10.8% (35/323). Patients were diagnosed in hospital with leaks on median day 4 compared with day 11 for patients diagnosed with leaks after readmission from home (P < 0.001). Defunctioned patients diagnosed with a leak had a longer median length of stay (24 vs 18.0 days, P = 0.31) but were more frequently managed non-operatively (100% vs 19.0%, P < 0.001) and had a lower admission rate to intensive care (9.5% vs 42.9%, P = 0.02) than patients who were not defunctioned at time of resection. Overall mortality from anastomotic leak was 2.9% (1/35). Ileostomies were reversed in 73.5% of patients (25/34).

DISCUSSION

Enhanced recovery enables early diagnosis of leaks following anterior resection. Defunctioning of patients with anastomotic leak lowers mortality.

Variation in landmarks for the rectum: an MRI study

AIM

This study aimed to assess the reliability of measurements and bony landmarks for the rectosigmoid junction on MRI.

METHOD

The staging MRI scans for 100 patients were reviewed. The junction of the mesorectum and mesocolon was used to identify the rectum and sigmoid. The performance of current metric measurements or bony landmarks was then compared against the actual anatomical bowel segment.

RESULTS

The mean distance of the sigmoid take-off from the anal verge was 12.6 cm (SD 1.8 cm, range 9.4-19.0 cm). At a cutoff of 12 cm, the anatomical bowel segment was found to be sigmoid colon rather than rectum in 35% of patients. At 15 and 16 cm the bowel segment was sigmoid in 84% and 96% of patients, respectively. At the sacral promontory and the third sacral segment, the bowel segment was sigmoid in 28% and 100% of patients, respectively.

CONCLUSION

Current definitions of the rectum that rely on arbitrary measurements or bony landmarks will not locate the correct point of transition between the rectum and sigmoid in the majority of patients. The sigmoid take-off offers an alternative, anatomically bespoke, landmark.

Cost-effectiveness of routine imaging of suspected appendicitis

Introduction The misdiagnosis of appendicitis and consequent removal of a normal appendix occurs in one in five patients in the UK. On the contrary, in healthcare systems with routine cross-sectional imaging of suspected appendicitis, the negative appendicectomy rate is around 5%. If we could reduce the rate in the UK to similar numbers, would this be cost effective? This study aimed to calculate the financial impact of negative appendicectomy at the Queen Alexandra Hospital and to explore whether a policy of routine imaging of such patients could reduce hospital costs. Materials and methods We performed a retrospective analysis of all appendicectomies over a 1-year period at our institution. Data were extracted on outcomes including appendix histology, operative time and length of stay to calculate the negative appendicectomy rate and to analyse costs. Results A total of 531 patients over 5 years of age had an appendicectomy. The negative appendicectomy rate was 22% (115/531). The additional financial costs of negative appendicectomy to the hospital during this period were £270,861. Universal imaging of all patients with right iliac fossa pain that could result in a 5% negative appendicectomy rate would cost between £67,200 and £165,600 per year but could save £33,896 (magnetic resonance imaging), £105,896 (computed tomography) or £132,296 (ultrasound) depending on imaging modality used. Conclusions Negative appendicectomy is still too frequent and results in additional financial burden to the health service. Routine imaging of patients with suspected appendicitis would not only reduce the negative appendicectomy rate but could lead to cost savings and a better service for our patients.

Pain and compression neuropathy in primary inguinal hernia

PURPOSE

Enlargement of the ilioinguinal nerve at the external inguinal ring is observed in 34% of patients undergoing primary open inguinal herniorrhaphy; in 88% of patients it occurs at the fascial edge where the hernia mushrooms with abdominal pressure. Compression neuropathy occurs near many anatomical nerve constriction sites and is associated with enlargement of the peripheral nerve accompanied by sensory changes.

METHODS

In this prospective study, Carolina Comfort Scale (CCS) questionnaire data was collected for 35 primary hernia repairs. Each patient underwent primary inguinal herniorrhaphy that included ilioinguinal neurectomy. All nerves were sampled proximal to the external inguinal ring. Any nerves with grossly increased overall diameter to any degree distal to the external ring were additionally sampled in the thickened portions. A neuropathologist performed histologic evaluation of the H&E-stained cross sections.

RESULTS

Paired comparison of proximal and distal nerves revealed a greater overall diameter and greater measured nerve-specific diameter in distal nerve segments. Nerves with increased overall diameter were also found to have a statistically significant positive correlation with four of eight pain measures. Additionally, increased nerve-specific diameter correlates with increased pain on four of eight pain values, but age effect on nerve diameter blunts this finding.

CONCLUSIONS

Increased preoperative CCS pain values in primary open inguinal hernia are significantly correlated with gross enlargement of the overall diameter and nerve-specific diameter of the ilioinguinal nerve beyond the external inguinal ring. This is consistent with a compression neuropathy.

Prevalence, management and outcome of traumatic diaphragm injuries managed by the Pietermaritzburg Metropolitan Trauma Service

INTRODUCTION This audit of traumatic diaphram injury (TDI) from a busy South African trauma service reviews the spectrum of disease and highlights current approaches to these injuries. METHODS The Pietermaritzburg Metropolitan Trauma Service (PMTS) has maintained an Electronic Surgical Registry (ESR) and a Hybrid Electronic Medical Record (HEMR) system since January 1st 2012. RESULTS A total of 105 TDIs were identified and repaired during the study period. The mean patient age was 30 years (range 15-68 years - SD 9.7). The majority (92.4%) of patients were male (97/105). Penetrating trauma was the leading mechanism of injury (94%). 75 patients sustained a TDI from a stab wound, and the remaining 24 injuries resulted from gunshot wounds. Multiple associated injuries and high morbidity was seen with right diaphragm injury, blunt trauma, gunshot wounds and chronic diaphragmatic hernias. CONCLUSIONS TDI is a fairly uncommon injury with a local incidence of 1.6%. It presents in a spectrum from the obvious to the occult. Multiple associated injuries and high morbidity occur following blunt trauma or gunshot wounds, right diaphragm injury and chronic diaphragmatic hernias. Diagnostic laparoscopy offers a diagnostic and therapeutic tool to prevent progression of occult TDI to chronic diaphragmatic hernias.

Novel Approach to Measuring the Droplet Detachment Force from Fibers

Determining the force required to detach a droplet from a fiber or from an assembly of fibers is of great importance to many applications. A novel technique is developed in this work to measure this force experimentally by using ferrofluid droplets in a magnetic field. Unlike previous methods reported in the literature, our technique does not require air flow or a mechanical object to detach the droplet from the fiber(s); therefore, it simplifies the experiment and also allows one to study the capillarity of the droplet-fiber system in a more isolated environment. In this article, we investigated the effects of the relative angle between intersecting fibers on the force required to detach a droplet from the fibers in the in-plane or out-of-plane direction. The in-plane and through-plane detachment forces were also predicted via numerical simulation and compared with the experimental results. Good agreement was observed between the numerical and experimental results. It was found that the relative angle between intersecting fibers has no significant effect on the detachment force in the out-of-plane direction. However, the detachment force in the in-plane direction depends strongly on the relative angle between the fibers, and it increases as this angle increases.

The value of ultrasonography in the diagnosis of appendicitis

INTRODUCTION

Ultrasonography is a commonly used investigation in the UK for patients with right iliac fossa pain where the diagnosis of appendicitis is unclear. The published sensitivity and specificity of ultrasonography is higher than the results observed by clinicians in every day practice. The aim of this study was to elucidate the real-world value of ultrasonography in the diagnosis of appendicitis, and its impact on negative appendicectomy rates (NAR).

METHODS

A retrospective multicentre audit was conducted at three UK hospitals over a twelve month period in 2012.

RESULTS

573 patients underwent ultrasonography prior to appendicectomy. The appendix was not visualised in 45% of scans. The sensitivity and specificity of ultrasonography for the diagnosis of appendicitis was 51.8% and 81.4%. The mean NAR was 26.7%, or 18.3% after a positive ultrasound scan.

CONCLUSION

In clinical practice at UK centres, ultrasonography commonly does not visualise the appendix, and has a low sensitivity for appendicitis. To reduce the NAR, management options include a return to observation and serial examination, increased use of CT or a commitment to improving the performance of ultrasonography.

Got central prostate pathology review? A cross-sectional audit of 2009 versus 2003 outcomes

196

Background: Prostate cancer is the most common non-cutaneous cancer in Canadian men; over 24,000 will be newly diagnosed and 4,300 will die from it in 2010. Estimating an individual's risk of disease spreading across the capsule and probability of recurrence with different treatment modalities is common practice in prostate cancer management and often drive the choice or extent of treatment options. A strong predictor of recurrence and organ confined disease is tumor grade. The literature recognizes differences in grading prostate cancer between genitourinary and non-specialized pathologists; we previously reported a 30% change in risk category (Low, GS 2-6; Int., GS 7; High, GS 8-10). However, this report was based on data from 2003/2004. A repeat audit was necessary given Gleason grading practice changes following the 2005 ISUP Consensus Conference.

Methods: Log books from 2009/10 where our Genitourinary Pathologists (GUP) reviewed prostate needle core biopsies were used to identify cases; a retrospective chart review was completed. The following variables were extracted: 1° Gleason score; 2° Gleason score; number of sites; % Gleason 4/5 pattern (overall); perineural invasion (present/absent); extracapsular extension (present/absent). Descriptive statistics were used to summarize the results.

Results: The charts of 132 patients having a GUP biopsy review were extracted. Seventeen percent (22/132) of cases changed risk category. Of the 47 low risk cases, 23% (11/47) were up-graded in risk category (21% by 1 category; 2% by 2 categories). Of the 46 intermediate risk cases, 15% (7/46) were up-graded and 2% (1/46) were down-graded. Of the 39 high risk cases, only 8% (3/39) were down-graded by 1 risk category. Comparatively, there was a 43% reduction in risk category change between 2003/04 (30%) and 2009/10 (17%).

Conclusions: Despite this reduction, a clinically significant proportion of patients changed pathologic risk category upon GUP review. Thus, it is recommended that prostate cancer pathology be routinely reviewed by a GUP as a best practice to optimize management and quality of care. Strategies are still needed to address disparities in pathologic grading and represent a potential area for further investigation.

No significant financial relationships to disclose.

Mycotic aneurysm of the posterior tibial artery -- a rare complication of bacterial endocarditis: a case report

Introduction

Distal arterial embolisation and subsequent aneurysm formation are rare occurrences and most are secondary to trauma. We have found no case reports that describe posterior tibial aneurysm formation secondary to bacterial endocarditis.

Case presentation

We report the case of a 47-year-old Caucasian man who, 2 years after an episode of subacute bacterial endocarditis, presented with signs and symptoms consistent with posterior tibial aneurysm formation.

Conclusion

Posterior tibial aneurysm formation is a rare occurrence, most commonly occurring after trauma and, although other causes have been described, to our knowledge, endocarditis has not been implicated before, and as such should therefore be borne in mind when dealing with cases where no obvious aetiology is evident.

Community based trials and informed consent in rural north India

Disease control has increasingly shifted towards large scale, disease specific, public health interventions. The emerging problems of HIV, hepatitis, malaria, typhoid, tuberculosis, childhood pneumonia, and meningitis have made community based trials of interventions a cost effective long term investment for the health of a population. The authors conducted this study to explore the complexities involved in obtaining informed consent to participation in rural north India, and how people there make decisions related to participation in clinical research.

Familial tetralogy of Fallot and glaucoma

All 3 daughters of a mother with glaucoma had a conotruncal abnormality of the heart and glaucoma. The presence of heart and eye anomaly may be coincidental; however, both may be related to abnormal development of neural crest. The pedigree suggests autosomal dominant inheritance in this family.

Characterization of an automated apparatus for precise control of inhalation chamber ethanol vapor and blood ethanol concentrations

Inhalation chambers with a monitoring and control apparatus for ethanol vapor exposure of small animals were constructed. A thermal conductivity detector was employed for continuous measurement of inhalation chamber ethanol vapor concentration. The concentration was maintained within a very narrow range (+/- 1 mg/liter) by incorporating into the design a feedback loop which controls the ethanol pump. As expected, the blood ethanol concentrations (BEC) of male Sprague-Dawley rats were positively and linearly correlated to the chamber ethanol concentration. When rats were exposed for 24 hr to a chamber ethanol concentration of 17, 25, or 32 mg/liter, correspondingly low, moderate, or high mean blood ethanol levels were obtained. When a large population of this strain of rats (n = 121) was exposed to a constant ethanol vapor concentration for 14 days (25 mg/liter) considerable interindividual variation in blood levels occurred. There was also individual variation over time in the BEC of animals monitored. The mean +/- SD BEC was 189 +/- 90 mg/100 ml for this population and a gaussian-like distribution was obtained with regard to BEC. Behavior characteristic of alcohol withdrawal was observed in rats with BEC greater than 120 mg/100 ml after 3.5, 7, or 14 days of exposure. This apparatus and inhalation paradigm make possible the precise control of chamber ethanol concentration which markedly enhances control over both intra- and intersubject fluctuation in blood ethanol levels during alcohol exposure and the comprehensive examination of relationships between a wide range of blood ethanol concentrations and their physiological and biochemical effects.

Infantile hypoventilation syndrome, neurenteric cyst, and syringobulbia

Hypoventilation syndrome was observed in an infant with a neurenteric cyst. She died at 9 months of age following episodic bradycardia and the loss of voluntary as well as autonomic respiratory control. There was a mediastinal neurenteric cyst with anterior spina bifida and extension into the upper thoracic spinal cord. Secondary syringomyelobulbia was present at necropsy. The syringobulbia involved the hypoglossal nuclei, the dorsal motor nuclei of the vagus in the lower medulla, the right nucleus ambiguus, the right fasciculus and nucleus solitarius, the right mediolateral reticular formation, and the right dorsal motor nucleus of the vagus at the level of the obex. This morphologic distribution is attributed to the intraspinal rupture and upward extension of the mucinous contents of the cyst, and appears to be responsible for the hypoventilation syndrome.