Hypercarbic Respiratory Failure Research Articles

Pitfalls in the Evaluation of Respiratory Failure in Myasthenia Gravis Patients: A Case Series

Objectives To highlight the importance of recognizing different presentations of respiratory failure due to myasthenic and non-myasthenic etiologies in myasthenia gravis (MG) patients. Methods We describe 3 patients with different presentations of respiratory failure in MG. Cases Patient 1 is a 49-year-old female with longstanding MG who presented with lethargy and neck weakness without notable respiratory distress. She was found to be in hypercarbic respiratory failure, which improved with plasmapheresis treatment. Patient 2 is a 58-year-old female who presented with ptosis, dysphagia, and dyspnea requiring intubation. Her hypophonia and dyspnea persisted despite escalation in MG treatment, and further workup revealed glottal stenosis secondary to granulomatosis with polyangiitis. Patient 3 is an 85-year-old female with MG presenting with refractory hypoxia, which was secondary to a large patent foramen ovale resulting in right-to-left shunting. Discussion All 3 cases emphasize the role of clinical reasoning and careful analysis based on thorough history taking, detailed neurologic exam and comprehensive laboratory findings to determine the etiologies for respiratory dysfunction in MG and provide appropriate treatment. Conclusion A lack of overt signs of respiratory distress in MG does not rule out the presence of respiratory failure due to the sedating effect of hypercapnia. There is a need to consider alternative etiologies of hypoxia in MG patients if typical symptoms or signs of MG exacerbations are absent.

Bias between capnometry and venous carbon dioxide during initial assessment of pediatric emergency department patients: A video-based study.

The bias of capnometry (ETCO2) and venous carbon dioxide (vpCO2) among pediatric emergency department (PED) patients triaged to critical care areas is unknown. We aimed to explore correlations and bias between ETCO2 and vpCO2¸and identify predictors of bias. This was an observational, video-based, retrospective study comparing ETCO2 and vpCO2. Pediatric patients with simultaneous ETCO2 and vpCO2 data were included. Our primary aim utilized linear regressions to determine correlations and Bland-Altman analysis to assess bias. Our secondary aim utilized multiple regression to identify clinical covariates contributing to bias. Covariates included age, respiratory rate, heart rate, mean arterial blood pressure, capnometry interface, PED diagnosis, and PED disposition. A total of 200 PED patients with ETCO2 and vpCO2 data were included. The median (interquartile range [IQR]) ETCO2, vpCO2, and ΔCO2 in mmHg were 38 (32, 46), 49 (41, 61), and 11 (4, 20), respectively. ETCO2 (r=0.76) and ΔCO2 (r=0.71) were highly correlated with vpCO2. The mean bias between ETCO2 and vpCO2 was -14.1mmHg (95% confidence interval [CI], -41.9 -13.7). The bias between ETCO2 and vpCO2 increased at higher values of each measure. ETCO2 sampling interface was the only independent predictor of vpCO2 in our multivariate analysis. Patients requiring bag-valve mask (BVM) ventilation had the highest median bias between ETCO2 and vpCO2 (29mmHg, IQR 15, 37). ETCO2 and vpCO2 were highly correlated. However, bias increased at higher levels of both ETCO2 and vpCO2. Among PED patients, ETCO2's ability to approximate vpCO2 diminishes with worsening hypercarbic respiratory failure.

Cannula associated deep vein thromboses in COVID-19 patients supported with VV ECMO.

VV ECMO is increasingly used as a rescue strategy for hypercarbic and hypoxic respiratory failure refractory to conventional management, and more than 14,000 patients with COVID-19 related respiratory failure have been supported with VV ECMO to date. One of the known complications of VV ECMO support is the development of cannula-associated deep vein thromboses (CaDVT). The purpose of this study was to identify the incidence of CaDVT in COVID-19 patients supported with VV ECMO as compared to non-COVID-19 patients. We hypothesized that due to the hypercoagulable state and longer duration of VV ECMO support required for patients with COVID-19, a higher incidence of CaDVT would be observed in these patients. This is a single center, retrospective observational study. About 291 non-trauma adult patients who were cannulated for VV ECMO and managed at our institution from January 1, 2014 to January 10, 2022 were included. The primary outcome was the presence of CaDVT 24 h after decannulation in COVID-19 versus non-COVID-19 patients. Our secondary outcome was continued presence of DVT on follow up imaging. CaDVT were defined as venous thrombi detected at prior cannulation sites. Both groups had a high incidence of CaDVT. There was no significant difference in the incidence of CaDVT in COVID-19 patients compared to non-COVID-19 patients (95% vs 88%, p = 0.13). Patients with COVID-19 had an increased incidence of persistent CaDVT on repeat imaging (78% vs 56%, p = 0.03). Given the high number of post-decannulation CaDVT in both groups, routine screening should be a part of post ECMO care in both populations. Repeat venous duplex ultrasound should be performed to assess for the need for ongoing treatment given the high incidence of CaDVT that persisted on repeat duplex scans.

Extracorporeal Carbon Dioxide Removal to De-escalate Venovenous Extracorporeal Membrane Oxygenation in Severe COVID-19 Acute Respiratory Distress Syndrome

In a subset of patients with COVID-19 acute respiratory distress syndrome (ARDS), there is a need for extracorporeal membrane oxygenation (ECMO) for pulmonary support. The primary extracorporeal support tool for severe COVID-19 ARDS is venovenous (VV) ECMO; however, after hypoxemic respiratory failure resolves, many patients experience refractory residual hypercarbic respiratory failure. Extracorporeal carbon dioxide removal (ECCO2R) for isolated hypercarbic type II respiratory failure can be used in select cases to deescalate patients from VV ECMO while the lung recovers the ability to exchange CO2. The objective of this study was to describe the authors' experience in using ECCO2R as a bridge from VV ECMO. Hemolung Respiratory Assist System (RAS) is a commercially available (ECCO2R) device, and the United States Food and Drug Administration accelerated its use under its Emergency Use Authorization for the treatment of refractory hypercarbic respiratory failure in COVID-19-induced ARDS. This created an environment in which selected and targeted mechanical circulatory support therapy for refractory hypercarbic respiratory failure could be addressed. This retrospective study describes the application of Hemolung RAS as a VV ECMO deescalation platform to treat refractory hypercarbic respiratory failure after the resolution of hypoxemic COVID-19 ARDS. A quaternary-care academic medical center, single institution. Patients with refractory hypercarbic respiratory failure after COVID-19 ARDS who were previously supported with VV ECMO. Twenty-one patients were placed on ECCO2R after VV ECMO for COVID-19 ARDS. Seventeen patients successfully were transitioned to ECCO2R and then decannulated; 3 patients required reescalation to VV ECMO secondary to hypercapnic respiratory failure, and 1 patient died while on ECCO2R. Five (23.8%) of the 21 patients were transitioned off of VV ECMO to ECCO2R, with a compliance of <20 (mL/cmH2O). Of these patients, 3 with low compliance were reescalated to VV ECMO. Extracorporeal carbon dioxide removal can be used to continue supportive methods for patients with refractory type 2 hypercarbic respiratory failure after COVID-19 ARDS for patients previously on VV ECMO. Patients with low compliance have a higher rate of reescalation to VV ECMO.

Acceptance of and adherence with long-term positive airway pressure treatment in adults with chronic obstructive pulmonary disease: A systematic review protocol.

Long-term noninvasive positive airway pressure (PAP) treatment is effective treatment for sleep-related breathing disorders and chronic hypercarbic respiratory failure secondary to chronic obstructive pulmonary disease (COPD). PAP treatment may be delivered as continuous positive airway pressure or noninvasive ventilation. Success in initiating PAP treatment and barriers to its use in adult patients with COPD are largely unknown. This systematic review aims to identify the acceptance of and adherence to PAP treatment prescribed for long-term use in adult patients with COPD and to summarize variables associated with these measures. Seven online electronic databases will be searched by an experienced medical librarian to identify records containing the concepts "obstructive airways disease" and "noninvasive positive airway pressure" and "acceptance" or "adherence". Randomized and non-randomized studies of interventions will be included. Citation lists from relevant articles will be reviewed, and experts will be contacted regarding unpublished studies. Abstracts from key conferences between 2018-2023 and Google Scholar search results will be reviewed for inclusion. Titles, abstracts and full texts will be reviewed independently for inclusion by two reviewers. Data extraction will be completed by one author using a pre-established form and primary outcomes confirmed by a second author. Methodological quality will be evaluated. If sufficient data are available for meta-analysis, a pooled summary statistic for the primary outcome will be calculated using a random-effects generic inverse-variance meta-analysis, weighted proportion or weighted medians-based approach. Subgroup analysis will explore clinically meaningful sources of heterogeneity. Variables that are associated with acceptance and adherence will be described. Long-term PAP treatment is a complex intervention prescribed to patients with COPD for several indications. Synthesis of the evidence on success with PAP treatment and variables associated with acceptance or adherence will inform program and policy development for supporting patients with COPD who are prescribed this therapy. Systematic review registration: This protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on July 13, 2021 (registration number CRD42021259262), with revisions submitted on April 17, 2023.

Pediatric extracorporeal life support for refractory status asthmaticus: ELSO Registry trends from the past decade.

Extracorporeal life support (ECLS) for status asthmaticus (SA) is rare. Increased safety and experience may increase utilization of ECLS for SA. We reviewed pediatric (<18 years old) patients requiring ECLS for SA between 1998 and 2019 within the Extracorporeal Life Support Organization (ELSO) Registry and Nemours Children's Health (NCH) system. We compared patient characteristics, pre-ECLS medications, clinical data, complications, and survival to discharge between Early (1988-2008) and Late (2009-2019) eras. From the ELSO Registry, we identified 173 children, 53 in Early and 120 in Late eras, with primary diagnosis of SA. Pre-ECLS hypercarbic respiratory failure was similar between eras (median pH 7.0 and pCO2 111 mm Hg). Venovenous mode (79% vs. 82%), median ECLS time (116 vs. 99 h), time to extubation (53 vs. 62 h), and hospital survival (89% vs. 88%) also remained similar. Intubation to cannulation time significantly decreased (20 vs. 10 h, p = 0.01). ECLS without complication occurred more in the Late era (19% vs. 39%, p < 0.01), with decreased hemorrhagic (24% vs. 12%, p = 0.05) and noncannula-related mechanical (19% vs. 6%, p = 0.008) complications. Within NCH, we identified six Late era patients. Pre-ECLS medication favored intravenous beta agonists, bronchodilators, magnesium sulfate, and steroids. One patient died from neurological complications following pre-ECLS cardiac arrest. Collective experience supports ECLS as a rescue therapy for pediatric SA. Survival to discharge remains good, and complication rates have improved. Pre-ECLS cardiac arrest may potentiate neurologic injury and impact survival. Further study is needed to evaluate causal relationships between complications and outcomes.

0994 Neuroblastoma as the Initial Manifestation of Familial PHOX2B NPARM Positive Congenital Central Hypoventilation Syndrome

Abstract Introduction Congenital Central Hypoventilation Syndrome (CCHS) is a genetic disorder of the autonomic nervous system caused by mutations in the PHOX2B gene. Children with CCHS often present as neonates in hypoxemic, hypercarbic respiratory failure. Most causative mutations are de novo Polyalanine Repeat Mutations (PARMs). Non-Polyalanine Repeat Mutations (NPARMs) have been associated with more severe disease, specifically the need for 24-hour ventilatory support, Hirschsprung disease, and neural crest tumors; however, NPARMs may have variable expressivity and incomplete penetrance, resulting in delayed or atypical presentations. We report a toddler with maxillary sinus neuroblastoma, which led to the diagnosis of familial PHOX2B NPARM positive CCHS. Report of case(s) A two-year-old boy presented with right-sided facial swelling. A facial CT uncovered a right maxillary sinus lytic lesion, and biopsy confirmed neuroblastoma. After full recovery from the procedure, he had persistent nocturnal hypoxemia and hypercapnia requiring bilevel positive airway pressure (PAP) during sleep, raising concern for CCHS. Genetic testing revealed a novel PHOX2B NPARM, c.428dup, which likely causes a frameshift and premature protein termination (p.Val144Glyfs*34). His maternal grandfather, mother and brothers tested positive for the same mutation. Family history revealed that his maternal grandfather and maternal great-uncles had frequent childhood apneic spells associated with syncope, his maternal grandfather is currently on nocturnal bilevel PAP, and his mother almost drowned as a younger child while having a breath-holding contest under water. His six-year-old brother underwent polysomnography which showed hypoventilation, now managed with bilevel PAP. His five-year-old brother also underwent polysomnography and does not require nocturnal ventilatory support at this time. Conclusion We report a rare case of familial PHOX2B NPARM positive CCHS which initially presented as maxillary sinus neuroblastoma. Additionally, the child and his family display varying disease severity despite having the same NPARM, highlighting the variable expressivity in this novel NPARM. Support (if any) None

“Trident Sign” in Spinal Cord Lymphoma (P7-4.003)

<h3>Objective:</h3> N/A <h3>Background:</h3> Chronic, progressive myelopathies with longitudinally-extensive T2-hyperintense lesions and specific gadolinium enhancement patterns, such as the axial “trident sign” of enhancement, have shown to be strongly suggestive of spinal cord sarcoidosis. However, the sensitivity and specificity of such enhancement patterns are not known. <h3>Design/Methods:</h3> Case report with description of history, examination, laboratory values, and imaging findings. <h3>Results:</h3> A 50-year-old woman presented with progressive left spastic hemiparesis over three weeks. MRI of the cervical spine revealed a longitudinally-extensive T2-hyperintense lesion with linear dorsal subpial enhancement and an axial trident pattern of enhancement. Cerebrospinal fluid analysis revealed a pleocytosis with a white blood cell count 20 cells/mm³ (89% lymphocytes), protein of 50 mg/dL, and glucose of 59 mg/dL with negative oligoclonal bands, cytology, and flow cytometry. Aquaporin-4-IgG and Myelin Oligodendrocyte Glycoprotein-IgG in serum were negative. Whole-body FDG-PET revealed increased uptake in the cervical cord but no other areas of systemic hypermetabolism. She was treated with three courses of IV methylprednisolone but her weakness continued to progress. Repeat MRI two months after her initial presentation showed persistent enhancement. Her neurologic examination revealed left spastic hemiplegia and moderate weakness of her right upper extremity. Given the chronic, progressive myelopathy, persistent trident enhancement pattern suggestive of spinal cord sarcoidosis, and the potential risks involved with a cervical cord biopsy, a course of infliximab was trialed empirically. Despite this, she continued to worsen neurologically and developed hypercarbic respiratory failure. Spinal cord biopsy was pursued, ultimately revealing infiltration by diffuse large B-cell lymphoma. <h3>Conclusions:</h3> Spinal cord lymphoma should be considered in patients presenting with chronic, progressive myelopathy and can present with similar enhancement patterns as spinal cord sarcoidosis. Atypical clinical features, such as rapid and severe neurologic worsening despite immunosuppression, should raise suspicion for diagnoses other than spinal cord sarcoidosis to allow for earlier detection and expedited disease-directed treatment. <b>Disclosure:</b> Dr. Griffin has nothing to disclose. Dr. Toledano has nothing to disclose. The institution of Dr. Flanagan has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Flanagan has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Flanagan has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Horizon Therapeutics. Dr. Flanagan has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Pharmacy times. The institution of Dr. Flanagan has received research support from Viela Bio. Dr. Flanagan has received research support from UCB. Dr. Flanagan has received publishing royalties from a publication relating to health care. Dr. Flanagan has a non-compensated relationship as a Member of medical Advisory Board with The MOG Project that is relevant to AAN interests or activities. Dr. Flanagan has a non-compensated relationship as a Editorial board member with Journal of The Neurologic Sciences that is relevant to AAN interests or activities. Dr. Flanagan has a non-compensated relationship as a Editorial board member with Neuroimmunology Reports that is relevant to AAN interests or activities. Dr. Mustafa has nothing to disclose.

Teaching NeuroImages: Ondine curse syndrome caused by dorsolateral medullary stroke

A 68-year-old man with an acute left dorsolateral medullary infarction (figure) had recurrent episodes of hypercarbic respiratory failure with sleep during hospitalization. While awake, the patient ventilated adequately, but when asleep, the patient developed a severe respiratory acidosis (pH 7.14, pCO2 >107) and became unarousable. He was intubated and his mentation improved rapidly. Eventually, he had a tracheostomy placed and continued to have prolonged apneic episodes with sleep during spontaneous breathing trials. The patient did not have central sleep apnea prior to the stroke.

RF19 | PSUN368 Surviving Insulinoma: Severe Insulin Resistance in the Face of Endogenous Hyperinsulinemia

Abstract Introduction Insulinoma is a rare pancreatic neuroendocrine tumor (PNET) accounting for 1-2% of pancreatic neoplasms. Usually benign, even small tumors can cause significant morbidity due to hypoglycemia. Surgical resection is preferable choice of treatment, but diagnosis is usually delayed and localization can be evasive. We present a case of insulinoma in a patient who battled his symptoms with high carbohydrate intake leading to massive weight gain associated with severe insulin resistance. Case A 70 year old male presented to the ED after being found unconscious in his home. Blood glucose was 34 mg/dl after missing a meal. He had a remote history of diabetes mellitus, which gradually resolved. Five years ago, he began experiencing sweats, tremors, headaches and confusion early in the morning or when fasting that improved with eating. He was hospitalized four years ago due to hypoglycemia where he was suspected to have endogenous hyperinsulinemia. CT abdomen at that time was unremarkable. Possibility of insulinoma was raised, but patient did not pursue further investigations. In the last 4 years, he avoided severe hypoglycemic events with frequents meals, but had gained more than 50 lbs with resultant BMI of 51 kg/m2. While admitted, he underwent a 72h fasting test showed glucose 42 mg/dl, insulin level was 84.8 IU/L (range &amp;lt;3), proinsulin was 105.7 (pmol/l) and C-peptide was 4.83 ng/ml (ref &amp;lt;0.2). EUS revealed 7 mm×4 mm mass in pancreatic body. FNAB confirmed well differentiated PNET, grade 1. CT abdomen remained unrevealing. He was started on weight based diazoxide therapy with resolution of hypoglycemic events and persistent hyperglycemia, which required high dose insulin therapy and improved with significant decrease in diazoxide dose. Hospitalization was complicated by hypoxic hypercarbic respiratory failure due to obesity hypoventilation syndrome, COVID19 infection and new onset rapid atrial fibrillation. Patient was deemed not to be a surgical candidate due to multiple comorbidities and his medical management was switched to octreotide with low dose insulin therapy, which patient tolerated well. Conclusion Diagnosis of insulinoma can be significantly delayed in cases with mild or slowly progressive course of the disease. We suggest that progressive development of severe insulin resistance in patients with baseline obesity and insulin resistance-driven DM2 can mask endogenous hyperinsulinemia for extended period of time. This gives a false sense of slower progression or even resolution of symptomatology, as well as diversion to alternative diagnoses, like postprandial hypoglycemia. We also argue that "resolution" of diabetes with significant weight gain, especially when associated with increased calorie intake through frequent meals and symptomatology suggestive of hypoglycemia should be a red flag for workup towards possible insulinoma, akin to suspecting adrenal insufficiency in diabetic patients with an unexplained decrease in insulin requirements. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Sunday, June 12, 2022 1:00 p.m. - 1:05 p.m.

A Multifaceted Educational Design Approach to Critical Care Rotation Improves Learner Confidence and Knowledge.

Purpose: We developed a pilot elective to enhance the critical care training experience for medical students through integration of didactic, simulation, and experiential learning with the goal to increase student confidence in caring for patients with critical illness and advance knowledge and competencies within core critical care topics. Approach: We created and piloted a 4-week critical care elective for fourth-year medical students pairing clinical experience with didactic and simulation-based training. Students completed two 2-week intensive care unit (ICU) rotations in both medical and surgical ICUs. Students received 6 half-days of didactics focusing on: respiratory failure, ventilator management, shock, acid/base, and discussions at the end of life. Didactic sessions were coupled with simulation-based training to reinforce content through application and provide opportunity to build procedural skills. Medical knowledge was assessed via multiple-choice questions delivered before and after course completion. Course grades were determined through clinical evaluations by faculty/residents, written examination, and simulation assessment. Pre- and postknowledge assessment performance was compared between students enrolled in the pilot and traditional curricula. The traditional curriculum involved clinical experience without formal didactics or simulation opportunities, and course grades were determined by evaluations only. Outcomes: No students received passing scores of 70% on the precourse medical assessment in either curriculum group. The mean score on the postcourse knowledge assessment for the novel-curriculum students (N = 13) was 21.8/30 (72.8%), compared with the 17/30 (56%) for the students in the traditional curriculum (N = 6). No students in the traditional curriculum received a passing score on the postcourse assessment. Before the course, few students felt “comfortable” or “very comfortable” managing common ICU conditions (acute respiratory distress syndrome, 0%; undifferentiated shock, acute hypercarbic respiratory failure, and identifying need for mechanical ventilation, 33%; acute hypoxemic respiratory failure and cardiogenic shock, 50%; septic and hypovolemic shock, 83%). At completion, there was an improvement in the reported level of comfort; 100% of students reported feeling “comfortable” or “very comfortable” with all topics, save for cardiogenic shock at 83%. Comfortability levels remained high on subsequent evaluation 12 months post-course (6 months into trainee’s intern year). Discussion: A limitation of traditional critical care curricula is that it lacks structure designed to ensure exposure to core critical care topics. It relies on the randomness of patient’s disease states present during a given rotation. Incorporating scheduled didactics ensures consistent exposure to these topics regardless of the patient cases on service. A limitation of this study is the small sample size of both the novel-curriculum group and the percentage of traditional curriculum students undergoing written assessment. Despite the small sample size (N = 13), this pilot demonstrates feasibility of consistent delivery of core content via didactics and simulation coupled with experiential learning. Our results may suggest benefit in this multimodal approach compared with experiential learning alone; however, further research is needed. Traditional assessment relies solely on clinical impression which is biased and often fails to capture an actionable level of detail. Lack of objective measures of assessment impedes identification of areas for improvement at the trainee level as well as within a curriculum. The use of multiple methods of assessment allows for mitigation of bias and overcomes some of the limitations of a single method alone. 1 Simulation assessment allows for greater practical assessment of procedural competency than written assessment. Significance: With this novel pilot curriculum incorporating multiple educational strategies, students improved their confidence and knowledge in core critical care topics. By harnessing didactic and simulation training to complement the clinical experience, consistent delivery of core content is assured. Furthermore, evaluation is strengthened through use of knowledge assessment questions and simulation-based assessment as compared with traditional evaluations which are largely subjective. More research is needed to understand the impact when scaled to a larger group.

TEMPOROMANDIBULAR JOINT DISLOCATION DUE TO NEAR SELF-EXTUBATION

TEMPOROMANDIBULAR JOINT DISLOCATION DUE TO NEAR SELF-EXTUBATION

STATUS ASTHMATICUS COMPLICATED BY RHABDOMYOLYSIS

STATUS ASTHMATICUS COMPLICATED BY RHABDOMYOLYSIS

Akut solunum yetmezliğinde optik sinir kılıf çapının prognostik önemi

Purpose: The primary aim of this study was to determine the role of the optic nerve sheath diameter (ONSD) measured using ultrasonography in the differentiation of hypoxemic respiratory failure and hypercarbic respiratory failure. The secondary aim was to determine the value of ONSD in predicting the clinical outcome in hypercarbic patients.&#x0D; Materials and Methods: Non-traumatic adult patients presenting with dyspnea were included in this study. Arterial blood gas and concurrent ONSD measurements were obtained from all patients included in the study during presentation and at the second hour of treatment. The patients were divided into two groups - hypoxic and hypercarbic respiratory failure. An equivalent number of healthy volunteers were enrolled as the control group. &#x0D; Result: Mean ONSD values were 3.8±0.2 mm in the 24 patients with type 1 respiratory failure, 5.2 ± 0.5 mm in the 25 patients with type 2 respiratory failure, and 3.9±0.3 mm in the healthy controls. The ONSD of the hypercarbic patients was statistically significantly greater than that of the hypoxic patients and healthy volunteers. The ONSD of the hypercarbic patients was 5.2±0.5mm at baseline and 4.4±0.6 mm after treatment, the difference being statistically significant. However, the difference in ONSD was not statistically significant in predicting hospitalization and mortality. &#x0D; Conclusion: Sonographically measured ONSD may be an effective parameter in the differential diagnosis of type 1 and 2 respiratory failure. ONSD values changed significantly with treatment in patients with type 2 respiratory failure.

An Uncommon Cause of Gastric Perforation.

A 53-year-old man with diabetes mellitus and chronic hepatitis B was admitted to our hospital because of shortness of breath, chest tightness, and subsequent loss of consciousness and urinary incontinence. After endotracheal intubation and positive pressure ventilation, the vital signs were stable. The blood test results showed that the white cell count (27.61 × 109/L) was elevated and the glucose level was 20.88 mg/dL. Abdominal computed tomography (CT) with intravenous contrast confirmed the presence of gas in the peritoneal cavity and suspicious thickening of the stomach wall at the cardia, consistent with a gastrointestinal tract perforation (Figure A). Exploratory laparotomy was performed. Bubbles and edema were found in the omental bursa or lesser sac (Figure B). Near the gastric cardia, there was a visible peptic ulcer with associated perforation. The tissue around the ulcer was biopsied and the perforation repaired. The patient recovered well after surgery. However, significant swelling of the left neck was observed during physical examination. On further questioning, the patient reported that the swelling had been present for 2 months, had improved, and then recurred 2 weeks before presentation. Neck CT showed enlargement of the left submandibular gland with uneven enhancement and multiple enlarged bilateral cervical and submandibular lymph nodes (Figure C). Postoperative pathological findings suggested poorly differentiated adenocarcinoma, small cell carcinoma, and metastasis of lymph nodes (2/10). Ten days after the first surgery, the patient underwent radical gastrectomy (total gastrectomy with Roux-en-Y anastomosis). The patient's initial presentation may have been related to hypercarbic respiratory failure due to upper airway obstruction from his adenocarcinoma metastases. The patient's emergent intubation may have led to a rapid increase in pressure in the stomach, resulting in perforation of his gastric ulcer. (Informed consent was obtained from the patient to publish these images.)

Directed Hypercapnia for Weaning From ECMO to Mechanical Ventilation—Progress or Just a Process?

In this issue of The Annals of Thoracic Surgery, Kluis and colleagues1Kluis A. Shih E. Squiers J.J. et al.Directed hypercapnia as a strategy to wean extracorporeal membrane oxygenation in COVID-19 pneumonia.Ann Thorac Surg. 2022; 114: e307-e309Abstract Full Text Full Text PDF Scopus (1) Google Scholar report a single-institution experience with 5 cases of severe COVID-19 acute respiratory distress syndrome (ARDS) with hypercarbic respiratory failure using directed hypercapnia as a strategy to wean patients from venovenous extracorporeal membrane oxygenation (ECMO). The authors instituted a directed hypercapnia approach in combination with metabolically compensated respiratory acidosis to terminate long-term ECMO support and to reduce associated morbidity and mortality. Five patients were successfully weaned off ECMO. One patient with preexisting kidney disease requiring renal replacement therapy ultimately died of refractory acidosis and sepsis. ECMO duration ranged from 56 to 167 days, highlighting the extended duration of support. More than 13,000 cases of COVID-19 requiring ECMO have been reported to the Extracorporeal Life Support Organization registry with a 47% in-hospital mortality.2Extracorporeal Life Support OrganizationELSO live registry dashboard of ECMO patient data.https://www.elso.org/Registry/ELSOLiveRegistryDashboard.aspxDate accessed: March 20, 2022Google Scholar Early use of ECMO for COVID-19 resulted in poor outcomes, with many clinicians discouraging this application.3Henry B.M. Lippi G. Poor survival with extracorporeal membrane oxygenation in acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19): pooled analysis of early reports.J Crit Care. 2020; 58: 27-28Crossref PubMed Scopus (144) Google Scholar As the pandemic progressed, ECMO use increased rapidly, and more recent data suggest similar outcomes to non-COVID ARDS.4Barbaro R.P. MacLaren G. Boonstra P.S. et al.Extracorporeal membrane oxygenation support in COVID-19: an international cohort study of the Extracorporeal Life Support Organization registry.Lancet. 2020; 396: 1071-1078Abstract Full Text Full Text PDF PubMed Scopus (420) Google Scholar Much of the management of ECMO and mechanical ventilation has been extrapolated from non-COVID ARDS populations. Whereas most centers use lung-protective ventilation, there are no standard guidelines for ventilator management in this setting. Institutional demands and experiences often dictate the pathway of care. The authors report an ECMO weaning protocol that successfully liberated patients from this high-risk, resource-intensive therapy, allowing discharge from a tertiary center to long-term acute rehabilitation facilities. At the individual patient level, this may translate into decreases in the morbidity and mortality associated with prolonged ECMO. At the health system level, the economic and resource allocation benefits associated with freeing up intensive care beds, staff, and resources could be immense. This protocol could be particularly valuable during high infectivity periods when the health system is significantly strained. Certain considerations temper enthusiasm for widespread adoption of this protocol. Individualized care is essential, and recovery is the primary aim. As reported, all survivors remain on assist-control ventilation, and long-term outcomes, including prospects for eventual ventilator liberation, are unknown. Patients may have been better served with sedative reduction, extubation, and ambulation on ECMO. In addition, proponents of directed hypercapnia must ensure that protocols do not restrict evaluation for lung transplantation. Outcomes from ECMO bridging to transplantation have improved because of better patient selection and protocolized management approaches. As highlighted in a recent US nationwide analysis published in the New England Journal of Medicine, lung transplantation is an important option for refractory COVID-19 ARDS or post-COVID fibrosis, with promising early outcomes including 95% 3-month survival in more than 200 recipients.5Roach A. Chikwe J. Catarino P. et al.Lung transplantation for Covid-19–related respiratory failure in the United States.N Engl J Med. 2022; 386: 1187-1188Crossref PubMed Scopus (24) Google Scholar Notwithstanding, there will likely be a role for directed hypercapnia in this population, which will be further delineated as more research is performed. Directed Hypercapnia as a Strategy to Wean Extracorporeal Membrane Oxygenation in COVID-19 PneumoniaThe Annals of Thoracic SurgeryVol. 114Issue 5PreviewCoronavirus disease 2019 pneumonia with respiratory failure refractory to maximum medical therapy has been successfully managed with venovenous extracorporeal membrane oxygenation. This report describes a process of using directed hypercapnia in 5 patients to wean them from prolonged extracorporeal support secondary to refractory hypercarbic respiratory failure. Full-Text PDF

Pulmonary Hypertension and Diastolic Heart Failure in an Adolescent African-American Cantú Syndrome Patient

<h3>Introduction</h3> Cantú syndrome is a rare congenital condition characterized by hypertrichosis, coarse facial features, cardiomegaly, skeletal abnormalities, and tortuous vasculature. While progress has been made in the understanding of the molecular basis of this disease, there is still much to be uncovered regarding its natural history. Here, we present the clinical course of an African-American male with Cantú syndrome. <h3>Case Report</h3> A 4-month-old African-American male presented to the hospital with respiratory distress. A large pericardial effusion was identified, which required a pericardial window. Cardiac catheterization revealed pulmonary hypertension. At age 4, a diagnosis of Cantú syndrome was made on the basis of developmental delay, cardiomegaly, history of pericardial effusion, pulmonary hypertension, coarse facial features, hypertrichosis, wide/thickened ribs, and osteopenia. He developed chronic diastolic heart failure secondary to cardiomegaly and chronic hypercarbic respiratory failure requiring home oxygen and nocturnal bi-level positive airway pressure (BiPAP) therapy. Pulmonary hypertension treatment was initiated with sildenafil at age 13, resulting in significant improvement in exercise tolerance. Cardiac catheterization at 17 years of age demonstrated worsening pulmonary hypertension with baseline RV pressures of 85/18 mmHg and pulmonary artery (PA) pressures of 85/40 mmHg. Baseline pulmonary vascular resistance (PVR) was 15.7 Woods Units/m2. Vasoreactivity to O2 and inhaled nitric oxide was demonstrated with PVR decreasing to 6.6 and 5.5 Woods Units/m2 respectively. Carvedilol and cardiac rehabilitation therapy were initiated at age 19. On a recent admission, he required milrinone support due to worsening right ventricular (RV) dysfunction which was weaned prior to discharge. <h3>Summary</h3> Cantú syndrome is a rare genetic condition and its prevalence and prognosis are still unknown. Interestingly, nearly all patients in the International Cantú Syndrome Registry are Caucasian while our patient is African-American. Additionally, with no family history of the disease, it is possible that his case represents a sporadic mutation. Unfortunately, our patient exhibited progressive heart failure, pulmonary hypertension, and hypercarbic respiratory failure during his adolescent years.

Miscellaneous (Others) P-OT001. Polymyxin-induced neurotoxicity masquerading as myasthenia gravis

Introduction. We describe a patient with polymyxin-induced neurotoxicity manifesting with a myasthenia-like syndrome. Objective: With the emergence of multi-drug resistant gram- negative bacilli, the use of polymyxins have renewed relevance, especially in the treatment of nosocomial infections. Frequently reported neurological adverse effects of polymyxin include paraesthesias, polyneuropathy and ataxia. Rarely, it can cause weakness secondary to neuromuscular blockade. Methods. We present a patient who had ventilation-dependent respiratory failure following polymyxin use. Results. A 62-year-old male was admitted for cholecystitis complicated by multi-drug resistant Escherichia Coli bacteraemia. Five days after initiation of polymyxin B, he developed two episodes of hypercarbic respiratory failure leading to recurrent cardiac arrests. Neurological examination revealed bilateral ptosis and fatiguable proximal weakness (proximal power MRC grade 1, distal power MRC grade 4), suggestive of a neuromuscular junction pathology. Repetitive nerve stimulation (RNS) revealed a decremental response and a characteristic U- shaped envelope pattern. The patient was started on a course of intravenous immunoglobulin due to concerns of myasthenic crisis unmasked by polymyxin, which was also promptly discontinued given the differential diagnosis of polymyxin-related neurotoxicity. Within 48 hours, he rapidly improved. Five days after cessation of polymyxin, he had full strength and complete resolution of ptosis. Interval RNS performed at this juncture normalised and acetylcholinesterase receptor antibodies returned negative. Further history taken after recovery revealed that he did not have history of droopy eyelids, diplopia or weakness prior to this presentation. Conclusion. Whilst few studies have highlighted weakness and respiratory failure from neuromuscular blockade as adverse effects of polymyxin, majority of these cases were reported between 1962 and 1973. With the renewed use of polymyxin in the era of antimicrobial resistance, physicians should have heightened awareness of this potentially serious complication. The clinical features of polymyxin-induced neurotoxicity may be difficult to distinguish from myasthenic crisis. Recognition and prompt discontinuation of polymyxin is essential.

Treatment of critically ill patients with acute hypercarbic respiratory failure by average volume‐assured pressure support mode

Average volume-assured pressure support (AVAPS), a dual mode, delivers a set tidal volume (TV) per kg by adjusting the pressure between upper and lower inspiratory positive airway pressures (IPAP). Thus, ventilation is presumed to be happened effectively by sending a guaranteed TV. This study was aimed to evaluate the effectiveness of AVAPS mode in critically ill patients with acute hypercarbic respiratory failure (HRF) and compare the results with bilevel positive airway pressure-spontaneous/timed (BPAP-S/T) mode. Sixty patients were assigned to BPAP-S/T (n=29) and AVAPS modes (n=31). Maximum IPAP was started at 20 cmH2 O and minimum IPAP was set at 5 cmH2 O higher than expiratory positive airway pressure (EPAP) in AVAPS mode. IPAP was started at 15 cmH2 O in BPAP-S/T mode. IPAP levels were titrated up to 30 cmH2 O during noninvasive mechanic ventilation (NIMV) with a targeted TV of 6-8 mL/kg. Patients were followed for 5 days. No differences were found in pH, paCO2 , HCO3 , TV and EPAP between the two groups when compared separately by days. Maximum IPAP levels were significantly high in AVAPS mode in all times (P<0.001). The length of stay (LOS) in intensive care unit (ICU) (P=0.994) and hospital (P=0.509), hours of NIMV use per day (P=0.101) and NIMV success rate (P=0.931) were identical between the two groups. ICU (P=0.931), hospital (P=0.800), 6-month (P=0.919) and 1-year (P=0.645) mortality rates were also not different between the both groups. AVAPS mode had similar efficiency with BPAP-S/T mode regarding the NIMV treatment success in critically ill patients with acute HRF.

Pediatric Lung Transplant for Pleuroparenchymal Fibroelastosis: Single Center Experience

Purpose Pleuroparenchymal fibroelastosis (PPFE) is a rare, progressive, restrictive lung disease characterized by hypercarbic respiratory failure. In pediatrics, it has been described in patients with a history of malignancy who have received a bone marrow transplant, chemotherapy, or radiotherapy. It is characterized by pleural thickening, fibrosis, subpleural elastosis, and intraalveolar collagen deposits. Survival is poor and the only therapy is lung transplantation. Little is known about the outcomes after lung transplant for PPFE in pediatric patients. Methods A single-center retrospective chart review of patients that underwent bilateral lung transplant for PPFE between 2010 and 2020 was done. Descriptive and outcomes data were collected and compared to overall survival after lung transplant for our center. Results Nine patients were transplanted for PPFE in the 10-year period. Six were male. The average age at referral for transplant was 12.5 (7 - 16) years. The average at transplant was 13.8 (9 - 16) years. All patients had a history of malignancy; the most common was neuroblastoma (6/9) followed by 1 rhabdomyosarcoma, 1 acute lymphoid leukemia, and 1 acute myeloid leukemia. Seven patients received radiation therapy (non thoracic). Five patients had a history of autologous bone marrow transplantation. The average time from chemotherapy to referral to lung transplant was 9 years (6 - 12). Six patients required donor lung resections. One required delayed chest closure for 48 hours. Currently, 4 patients are alive, 4 deceased, and 1 lost to follow-up due to the transfer of care. The longest surviving patient is 3.7 years post transplant. The median survival after transplantation of the 4 deceased patients was 2.2 (1.3 - 6.3) years. Median survival post lung transplant for any reason is 6.6 years at our center. Conclusion Our experience with PPFE has been reflective of what has been published in the literature. All patients had a previous malignancy. Our limited data indicate worse outcomes compared to our overall center survival. Six patients required donor lung resizing due to the severely restrictive and small thoracic cavity size, resulting in increased morbidity. There is a need for further research to determine if lung transplantation for PPFE is an indicated therapy given the apparent risk of poor outcomes and higher morbidity.