Elevated Intrathoracic Pressure Research Articles

Traumatic Diaphragmatic Rupture Leading to Tension Gastrothorax: A Critical Case Report and Surgical Insight

Traumatic diaphragmatic rupture (TDR) is a serious but relatively uncommon injury, often resulting from blunt trauma, particularly motor vehicle accidents. Among these, blunt TDR presents with more severe outcomes than penetrating injuries, including higher mortality rates. A life-threatening complication of TDR is gastrothorax, which occurs when the stomach herniates into the thoracic cavity, leading to elevated intrathoracic pressure and potentially fatal consequences such as respiratory failure or cardiac arrest. This case reported a 23-year-old male who sustained a motor vehicle collision, presenting with progressive shortness of breath, nausea, and vomiting 15 hours post-injury. Imaging confirmed a diaphragmatic rupture with associated tension gastrothorax. Immediate intervention with nasogastric tube placement provided symptom relief, followed by exploratory laparotomy to repair the diaphragmatic defect. The patient's recovery was uneventful, demonstrating the critical importance of early diagnosis and timely surgical management in cases of TDR with gastrothorax. Traumatic diaphragmatic rupture occurs in approximately 0.8–1.6% of trauma cases, with motor vehicle accidents being the leading cause. Due to its potential for delayed diagnosis, the rupture is often missed initially, leading to higher rates of morbidity and mortality. Early detection is critical, as it can prevent serious complications such as bowel herniation into the thoracic cavity, respiratory distress, or even death.

Cerebral hemodynamics and optic nerve sheath diameter acquired via neurosonology in critical patients with severe coronavirus disease: experience of a national referral hospital in Peru.

We aimed to describe the neurosonological findings related to cerebral hemodynamics acquired using transcranial Doppler and to determine the frequency of elevated ICP by optic nerve sheath diameter (ONSD) measurement in patients with severe coronavirus disease (COVID-19) hospitalized in the intensive care unit of a national referral hospital in Peru. We included a retrospective cohort of adult patients hospitalized with severe COVID-19 and acute respiratory failure within the first 7 days of mechanical ventilation under deep sedoanalgesia, with or without neuromuscular blockade who underwent ocular ultrasound and transcranial Doppler. We determine the frequency of elevated ICP by measuring the diameter of the optic nerve sheath, choosing as best cut-off value a diameter equal to or >5.8 mm. We also determine the frequency of sonographic patterns obtained by transcranial Doppler. Through insonation of the middle cerebral artery. Likewise, we evaluated the associations of clinical, mechanical ventilator, and arterial blood gas variables with ONSD ≥5.8 mm and pulsatility index (PI) ≥1.1. We also evaluated the associations of hemodynamic findings and ONSD with mortality the effect size was estimated using Poisson regression models with robust variance. This study included 142 patients. The mean age was 51.39 ± 13.3 years, and 78.9% of patients were male. Vasopressors were used in 45.1% of patients, and mean arterial pressure was 81.87 ± 10.64 mmHg. The mean partial pressure of carbon dioxide (PaCO2) was elevated (54.08 ± 16.01 mmHg). Elevated intracranial pressure was seen in 83.1% of patients, as estimated based on ONSD ≥5.8 mm. A mortality rate of 16.2% was reported. In the multivariate analysis, age was associated with elevated ONSD (risk ratio [RR] = 1.07). PaCO2 was a protective factor (RR = 0.64) in the cases of PI ≥ 1.1. In the mortality analysis, the mean velocity was a risk factor for mortality (RR = 1.15). A high rate of intracranial hypertension was reported, with ONSD measurement being the most reliable method for estimation. The increase in ICP measured by ONSD in patients with severe COVID-19 on mechanical ventilation is not associated to hypercapnia or elevated intrathoracic pressures derived from protective mechanical ventilation.

Specific features of anesthetic management in simultaneous pancreas and kidney transplantation in a recipient with morbid obesity

Introduction. Anesthetic management in simultaneous pancreas and kidney transplantation in recipients has some specific features. In addition to the presence of underlying pathology in the form of type 1 diabetes mellitus and secondary diabetic complications, pronounced comorbidities can often make some difficulties for an anesthesiologist.Aim. We have reported a clinical case showing the specific features of anesthetic support for simultaneous pancreas and kidney transplantation in a recipient with morbid obesity.Clinical Case Report. Specific features of the anesthetic management of a 42-year-old patient L. with morbid obesity (body mass index 43.3 kg/m2) and hypertension who underwent simultaneous pancreas and kidney transplantation have been described. A preoperative examination of this patient revealed predictors of difficult airways, so endoscopically assisted intubation was performed. The Trendelenburg position of the patient during surgical intervention due to an excess body weight led to the increased intrathoracic pressure intraoperatively. The pressure ventilation mode, the neutral position of the patient on the operating table, and the monitoring of ventilation efficiency made it possible to return the elevated intrathoracic pressure to normal. A preoperative examination by a cardiologist, timely diagnosis and treatment of hypertension at the stage of placing the patient on the waiting list made it possible to exclude adverse hemodynamic reactions at the main stages of the operation. The patient was extubated on surgery completion in the Operating Room. The pancreatic graft function and the kidney graft function were satisfactory.Conclusion. Our approaches ensured the safety and efficacy of anesthesiological support and contributed to the successful implementation of simultaneous pancreas and kidney transplantation in the recipient having the concomitant pathology in the form of morbid obesity.

Abstract 15756: To Close or Not to Close: A Case of Multisystem Immune Checkpoint Inhibitor Toxicity and PFO

Introduction: Recent emergence of immune checkpoint inhibitors (ICIs) in oncologic treatments has led to increasing research on their side effect profile. Myocarditis occurs in roughly 0.04-1.14% of patients treated with ICIs and is associated with up to 50% mortality. We present a case of multisystem ICI toxicity requiring comprehensive evaluation to ultimately reveal a PFO shunt as the cause of persistent hypoxemia. Case: A 67-year-old male with Stage IIIC cutaneous melanoma presented with non-radiating pleuritic chest pain, diplopia, dyspnea and syncope. ECG showed high grade AV block and right bundle branch block. Labs showed elevated troponin, creatinine kinase and inflammatory markers. An echocardiogram showed edematous myocardium, a small pericardial effusion, and akinetic apical/inferior septal segments. Despite diuresis, 5g of methylprednisolone, IV immunoglobulin plus mycophenolate and resolution of AV block, the patient had hypoxemia on 100% FiO2. He underwent a CTA (which ruled out PE and ICI-induced pneumonitis) and fluoroscopic sniff test (revealing bilateral moderate diaphragm paresis). A recent cardiac catheterization on prior admission showed no obstructive coronary disease. Arterial blood gas showed pO2 120 mmHg without hypercapnia on 100% FiO2. We suspected a shunt as the underlying cause and obtained a bubble study disclosing a large (> 25 bubble) PFO with right-to-left shunt. Results: Given the timing of symptoms, it was determined that pembrolizumab administration caused myocarditis and myositis with diaphragmatic paresis. In patients with pulmonary disease or diaphragmatic paresis, elevated intrathoracic and pulmonary artery pressures have been a proposed mechanism of acute worsening of right-to-left shunt resulting in hypoxemia. The patient underwent right heart catheterization and PFO closure using Gore Cardioform septal occluder with resolution of hypoxemia. A repeat echocardiogram obtained 1 month later was normal. Conclusion: All concerning clinical symptoms in the setting of ICI use require a thorough evaluation. In this case, persistent hypoxemia despite treatment for ICI toxicity unmasked a large PFO requiring closure. A multisystem approach should be used to assess suspected ICI myocarditis.

Impact of Esophageal Pressure Measurement on Pulmonary Hypertension Diagnosis in Patients With Obesity

Elevated intrathoracic pressure could affect pulmonary vascular pressure measurements and influence pulmonary hypertension (PH) diagnosis and classification. Esophageal pressure (Pes) measurement adjusts for the increase in intrathoracic pressure, better reflecting the pulmonary hemodynamics in patients with obesity. In individuals with obesity, what is the impact of adjusting pulmonary hemodynamic determinations for Pes on PH diagnosis and classification? Can Pes be estimated by positional or respiratory hemodynamic changes? In this prospective cohort study, we included patients with obesity who underwent right heart catheterization and demonstrated elevated pulmonary artery wedge pressure (PAWP;≥ 12mmHg). After placement of an esophageal balloon, we performed pressure determination using an air-filled transducer connected to a regular hemodynamic monitor. We measured pulmonary pressures changes when sitting and the variations during the respiratory cycle. We included 53 patients (mean ± SD age, 59 ± 12 years; mean ± SD BMI, 44.4 ± 10.2kg/m2). Supine end-expiratory pressures revealed a mean pulmonary artery pressure of > 20mmHg in all patients and a PAWP of >15mmHg in most patients (n= 50). The Pes adjustment led to a significant decrease in percentage of patients with postcapillary PH (from 60%to 8%) and combined precapillary and postcapillary PH (from 34%to 11%), at the expense of an increase in percentage of patients with no PH (0%to 23%), isolated precapillary PH (2%to 25%), and undifferentiated PH (4%to 34%). Adjusting pulmonary hemodynamics for Pes in patients with obesity leads to a pronounced reduction in the number of patients who receive a diagnosis of postcapillary PH. Measuring Pes should be considered in patients with obesity, particularly those with elevated PAWP.

Evidence of an active Cushing reflex in a preterm neonate with hyaline membrane disease: a case report

BackgroundThe Cushing reflex does not appear to have been described in preterm neonates. This case report shows the presence of an active Cushing reflex in a 32-week preterm neonate with hyaline membrane disease.Case presentationThe 1.94 kg Caucasian infant was delivered by caesarean section following concerns about possible maternal infection and fetal compromise. Chest X-ray showed mild-to-moderate hyaline membrane disease and treatment was initiated with supplemental oxygen and nasal continuous positive airway pressure. It is probable that a pneumothorax occurred at 5–6 hours of age, with progression during the day. Interstitial air, pneumomediastinum, and tension pneumothorax were diagnosed on subsequent X-ray, and ultrasound of the brain showed a grade IV intraventricular hemorrhage. A review of the nurses’ recordings of heart rate, blood pressure, and respiratory rate showed a progressive increase in blood pressure accompanied by slowing of the heart rate and irregular respiration. These are features of the Cushing reflex that is elicited in response to raised intracranial pressure.ConclusionWhile well-described in older children and adults, in neonates the Cushing reflex has mainly been described in animal experiments and infants who have developed hydrocephalus. It is likely that in this case, the reflex was elicited as a result of a progressive increase in intracranial pressure due to the combination of elevated intrathoracic pressure, obstructed venous return from the brain, and concurrent intraventricular hemorrhage.

Esophageal balloon calibration during Sigh: A physiologic, randomized, cross-over study

Optimal esophageal balloon filling volume (Vbest) depends on the intrathoracic pressure. During Sigh breath delivered by the ventilator machine, esophageal balloon is surrounded by elevated intrathoracic pressure that might require higher filling volume for accurate measure of tidal changes in esophageal pressure (Pes). The primary aim of our investigation was to evaluate and compare Vbest during volume controlled and pressure support breaths vs. Sigh breath. Twenty adult patients requiring invasive volume-controlled ventilation (VCV) for hypoxemic acute respiratory failure were enrolled. After the insertion of a naso-gastric catheter equipped with 10ml esophageal balloon, each patient underwent three 30-min trials as follows: VCV, pressure support ventilation (PSV), and PSV+Sigh. Sigh was added to PSV as 35 cmH2O pressure-controlled breath over 4s, once per minute. PSV and PSV+Sigh were randomly applied and, at the end of each step, esophageal balloon calibration was performed. Vbest was higher for Sigh breath (4.5 [3.0-6.8] ml) compared to VCV (1.5 [1.0-2.9] ml, P=0.0004) and PSV tidal breath (1.0 [0.5-2.4] ml, P<0.0001). During Sigh breath, applying a calibrated approach for Pes assessment, a higher Vbest was required compared to VCV and PSV tidal breath.

PARADOXICAL WORSENING HYPOXEMIA WITH MECHANICAL VENTILATION IN A PATIENT WITH BILATERAL PNEUMONIA

SESSION TITLE: Medical Student/Resident Pulmonary Physiology SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Chronic obstructive pulmonary disease (COPD) is associated with chronic hypoxemia due to right-to-left shunting. We present a patient with a history of COPD and adenocarcinoma with bilateral pneumonia who developed severe hypoxemia on mechanical ventilation. CASE PRESENTATION: A 64-year-old male with a history of COPD and Stage IIIA adenocarcinoma presented in respiratory distress. Chest x-ray (CXR) revealed bilateral opacities. Arterial blood gas (ABG) on a non-rebreather mask with a fraction of inspired oxygen (FiO2) 100% was pH of 7.42, pCO2 40.9, and PaO2 of 79.3. He was started on broad spectrum antibiotics. CT chest angiogram was negative for a pulmonary embolism, but showed a 2.8 cm spiculated mass in the right upper lobe, and extensive bilateral ground glass opacities. Echocardiography confirmed right-to-left intrapulmonary shunting with normal right ventricular function. With worsening hypoxemia, despite noninvasive-positive-pressure support, the patient was intubated with etomidate and rocuronium and placed on volume-control ventilation (VCV) with positive-end-expiratory pressure (PEEP) 5 cmH2O; respiratory rate 16, and FiO2 100%. His SpO2 dropped to 60% and was switched to pressure-control ventilation. He subsequently became hypotensive and bradycardic with a PEA arrest. A code blue was initiated with ROSC after several minutes. Repeat ABG showed: pH 7.154, pCO2 52, PaO2 63.7; and SaO2 76.4. Patient was changed back to VCV with PEEP 10 cmH2O; respiratory rate 24, and FiO2 100% that improved SpO2 to 80-82% temporarily. Despite trials of escalating PEEP and mode changes, the SpO2 declined to 50-60%. After an aborted recruitment maneuver, a second episode of PEA arrest occurred with ROSC, but he continued to have low SpO2 values, which was confirmed with ABG. Repeat CXR showed worsening bilateral infiltrates. A bedside ultrasound showed forceful cardiac contractions, which reduced the likelihood of cardiogenic pulmonary edema. Blood pressure continued to fall despite increasing doses of vasopressors. Family decided no further intervention and the patient expired. DISCUSSION: Pneumonia causes increased pulmonary vascular resistance; PEEP can improve oxygenation by recruiting alveoli, but at the expense of elevated intrathoracic pressures (ITP). In focal pathologies, PEEP paradoxically worsens ventilation-perfusion ratios and gas exchange.1 No set recommendations for ventilator management with worsening hypoxemia in right-to-left intrapulmonary shunting have been established.2 Airway pressure release ventilation decreases shunt fraction has been shown to improve V/Q matching, increase cardiac output, and decrease right atrial pressure by facilitating low airway pressure. Our patient’s rapid clinical decline prevented such attempts. CONCLUSIONS: When hypoxemia worsens paradoxically to increasing oxygenation maneuvers, clinicians should consider the possibility of right-to-left shunt. Reference #1: Annals of American Thoracic Society 11:2014 Reference #2: Respiratory Care 57:2012 DISCLOSURES: No relevant relationships by Sravya Brahmandam, source=Web Response no disclosure on file for Timothy Janz

Spontaneous Pneumomediastinum From Sustained Valsalva

SESSION TITLE: Student/Resident Case Report Poster - Disorders of the Mediastinum SESSION TYPE: Student/Resident Case Report Poster PRESENTED ON: Tuesday, October 25, 2016 at 01:30 PM - 02:30 PM INTRODUCTION: This case discusses the physiology of pneumomediastinum secondary to sustained valsalva and correct management. CASE PRESENTATION: Twenty year old Hispanic male presented for one day history of nausea, fatigue and chest pain. The patient reports daily marijuana use for recreation. The day prior to admission, he smoked 11 grams which initiated several instances of nonbloody and nonbilious vomiting. He reported sharp and retrosternal chest pain not worsened with exertion. A few hours after being admitted, his chest pain and nausea had subsided. X-rays and CT scans showed air within the mediastinum as well as air in the subcutaneous chest wall. The patient did not require subsequent oxygen support or pain control. He was discharged the next day from the hospital with outpatient followup and extensive counseling on drug abuse. DISCUSSION: Repeated Valsalva maneuvers are performed to increase the high during marijuana smoking. The elevated intrathoracic pressure leads to rupture of alveolar membrane causing positive pressure gradient of air from lungs into the mediastinum. In a retrospective study of 500 patients with mediastinal emphysema, 15 patients had repeated Valsalva maneuvers secondary to marijuana use. In all the cases, the patients recovered without further sequelae in two to five days. The differential diagnosis is broad and includes alveolar rupture, tracheobronchial injury, esophageal perforation, head/neck surgery and abdominal injury. Severe asthma, airway obstruction and rib fractures may lead to alveolar rupture. Iatrogenic injury and trauma to trachea, head, neck and abdomen often lead to tracking air down to the mediastinum, The most life threatening cause of pneumomediastinum is secondary to esophageal perforation. Tachycardia is the initial SIRS response within 24 to 48 hours. The Mackler's triad of vomiting, lower chest pain and subcutaneous emphysema may be present. Chest radiograph with water soluble material or a CT scan would be appropriate to identify perforation. Many patients need surgery as irrigation and debridement of mediastinum is required as well as closure of perforation. Percutaneous drainage is often a possibility if it perforation is in the neck and is easilly accessible. CONCLUSIONS: Repeated sustained valsalva often results in pneumothorax and pneumomediastinum. All reported cases in the literature show safe observation for one to two days is adequate if esophageal perforation is not suspected. If esophgeal perforation occurs, tachycardia is often first symptom with SIRS response occuring within 24-48 hours. Emergent surgery and/or percutaneous drainage may be indicated if it is not a contained perforation. Reference #1: Esophageal perforation and Acute Bacterial Mediastinitis: Other Causes of Chest Pain That Can be Easily Missed Cross et al. Medicine (Baltimore) 2015 Reference #2: Pneumomediastinum in heroin and marijuana users Mattox et al. Journal of the American College of Emergency Physicians 1976 DISCLOSURE: The following authors have nothing to disclose: Aritra Sen, Pratik Doshi, Bela Patel No Product/Research Disclosure Information

Three Simultaneous Cases of Spontaneous Pneumomediastinum With Epidural Pneumatosis During Vocal Training

The aim of this study was to describe a case series of three simultaneous cases of spontaneous pneumomediastinum (SPM) with epidural pneumatosis during vocal training. A report of three cases with chart review was performed. Literature review was carried out using PubMed. This was an extremely rare case series where at least three of the 20 participants of a vocal training in a self-development seminar developed SPM, epidural pneumatosis, pneumothorax, and subcutaneous emphysema. All cases improved with bed rest. Simultaneous cases of SPM have been reported in the past. However, the cause of simultaneous occurrence has not been explained clearly. In our cases, continuous excessive vocal training may have caused intrathoracic pressure to rise, causing SPM at a high prevalence. Epidural pneumatosis is a rare finding. Studies on epidural pneumatosis complicating SPM are limited. Air is said to easily pass through the cervical region owing to the close proximity between the mediastinum and the upper spine, resulting in epidural pneumatosis. Elevated intrathoracic pressure while the glottis is closed may worsen the risk for epidural pneumatosis. In this seminar, continuous effortful vocal training at full pitch with few pauses for breath may have contributed to this simultaneous occurrence. We report three simultaneous cases of SPM and epidural pneumatosis due to demanding vocal training. Further research on this subject is desired to identify risk factors.

Ischemic stroke related to an amniotic fluid embolism during labor

We report a young woman who survived multiple cerebral infarctions related to an amniotic fluid embolism (AFE) during labor. To our knowledge, an embolic stroke due to the coexistence of an AFE and patent foramen ovale (PFO) has not been reported. We describe the patient’s clinical and radiological features and discuss the stroke mechanism in relation to our AFE hypothesis. A 32-year-old woman presented to the emergency room after experiencing convulsions during labor (blood pressure, 64/28mmHg; oxygen saturation, 67%). She was in a stupor, and her response to painful stimuli on the right side was weaker than on the left side. Acute stroke was considered as a possible cause. Additionally, an AFE was suspected due to cardiopulmonary arrest during labor. Brain MRI revealed multiple territory embolic infarctions. The transcranial Doppler with bubble study demonstrated a right-to-left shunt during the Valsalva maneuver. A transesophageal echocardiogram revealed a PFO with a right-to-left shunt. The elevated intrathoracic pressure during labor may have caused blood to flow backward through the heart, shunting blood from the right side to the left through the PFO. In cases such as this, an amniotic fluid embolus may travel directly from the venous to the arterial circulation via the PFO, leading to multiple cerebral infarctions.

Haemodynamic Effects of Lung Recruitment Manoeuvres.

Atelectasis caused by lung injury leads to increased intrapulmonary shunt, venous admixture, and hypoxaemia. Lung recruitment manoeuvres aim to quickly reverse this scenario by applying increased airway pressures for a short period of time which meant to open the collapsed alveoli. Although the procedure can improve oxygenation, but due to the heart-lung and right and left ventricle interactions elevated intrathoracic pressures can inflict serious effects on the cardiovascular system. The purpose of this paper is to give an overview on the pathophysiological background of the heart-lung interactions and the best way to monitor these changes during lung recruitment.

Real-time phase-contrast flow MRI of the ascending aorta and superior vena cava as a function of intrathoracic pressure (Valsalva manoeuvre)

Real-time phase-contrast flow MRI at high spatiotemporal resolution was applied to simultaneously evaluate haemodynamic functions in the ascending aorta (AA) and superior vena cava (SVC) during elevated intrathoracic pressure (Valsalva manoeuvre). Real-time phase-contrast flow MRI at 3 T was based on highly undersampled radial gradient-echo acquisitions and phase-sensitive image reconstructions by regularized non-linear inversion. Dynamic alterations of flow parameters were obtained for 19 subjects at 40-ms temporal resolution, 1.33-mm in-plane resolution and 6-mm section thickness. Real-time measurements were performed during normal breathing (10 s), increased intrathoracic pressure (10 s) and recovery (20 s). Real-time measurements were technically successful in all volunteers. During the Valsalva manoeuvre (late strain) and relative to values during normal breathing, the mean peak flow velocity and flow volume decreased significantly in both vessels (p < 0.001) followed by a return to normal parameters within the first 10 s of recovery in the AA. By contrast, flow in the SVC presented with a brief (1-2 heartbeats) but strong overshoot of both the peak velocity and blood volume immediately after pressure release followed by rapid normalization. Real-time phase-contrast flow MRI may assess cardiac haemodynamics non-invasively, in multiple vessels, across the entire luminal area and at high temporal and spatial resolution. Future clinical applications of this technique promise new insights into haemodynamic alterations associated with pre-clinical congestive heart failure or diastolic dysfunction, especially in cases where echocardiography is technically compromised.

Bag ‘em or tube ‘em: how to decide

In an effort to identify or at least shed light on optimal out-ofhospital cardiac arrest (OHCA) airway management strategies, McMullan et al [1] compared OHCA outcomes between patients receiving endotracheal intubation (ETI) vs supraglottic airway (SGA) and between patients receiving ETI or SGA and those receiving no advanced airway. They found that survival was higher among OHCA receiving ETI than those receiving SGA and for patients who received no advanced airway than those receiving ETI or SGA. Although their findings of an association of improved outcomes with no advanced airway management are consistent with previous reports, they urged caution in the interpretation of those and the current findings. Confounding by indication is of major influence in studies of medical interventions. It was noted that, unlike the comparison of ETI vs SGA, the observed survival differences between the airway and nonairway groups were very large, even after stratification by initial electrocardiographic rhythm, propensity score adjustment, and propensity score matching. They suggested that the large associations—despite the use of multivariable adjustment and propensity score matching— reflected the presence of unmeasured and immeasurable confounders. One significant confounding factor that was not accounted for in their analyses is the presence of witnessed gasping and/or gasping upon arrival of emergency rescuers. Gasping is the only source of clinically significant ventilation during chest compressions only (CCO) cardiopulmonary resuscitation (CPR) [2-4]. Moreover, studies in animals demonstrate that spontaneous gasping alone during ventricular fibrillation cardiac arrest generates cardiac output, maintains more optimal amplitudes of ventricular fibrillation waveforms, circulates blood to the brain, and decreases intracranial pressure (ICP) [5-7]. Furthermore, the elevation of intrathoracic pressure during standard CCO-CPR in animals (caused by air trapping in the lungs [8]) not only generates carotid pressure and flow but also increases ICP [9]. Intracranial pressure is also known to increase during the chest compression phase of conventional CPR in humans andmay be what limits cerebral blood flow [9]. The lower ICP is, the lower resistance is to forward blood flow to the brain. This may explain why performance of standard CCO-CPR in animals at 100 per minute results in only 25% of normal perfusion to the brain, but during LUCAS CCO-CPR, cortical cerebral blood flow is significantly increased [10]. Therefore, gasping not only significantly improves the effective-

ABSTRACT 524

Background and aims: In patients who develop dilated cardiomyopathy (DCM) due to acute fulminant myocarditis, afterload reduction plays a crucial role during management. Although higher levels of intrathoracic pressure (ITP) reduce left ventricular afterload, it is generally acknowledged that elevated ITP causes hemodynamic compromise due to predominance of other complex cardiopulmonary interactions. Aims: Demonstrate that increasing ITP can improve cardiac function in selected patients. Case Report: A 4 year old girl presenting with severe hemodynamic and respiratory compromise was admitted to the PICU with vasopressor, inotropic, ventilator and fluid support while maintaining euvolemia. Echocardiography (ECG) on admission revealed evidence of myocarditis and DCM with an ejection fraction (EF) of 30%. Repeat ECG 24 hours later revealed no improvement. ECG guided adjustment of ventilator settings was decided. No change in medication or dosage was done during the adjustment, eliminating other potential confounders. Case is presented as educational material and is not subject to IRB review (patient is deceased and all attempts to remove identifiable information were made).FigureResults: EF improvement (47%) was noted after gradually increasing positive end-expiratory pressure (PEEP) from 5 to 10 cmH20. Effect was maintained on subsequent ECGs on the following days. Conclusions: This case demonstrates improvement in cardiac function after increasing PEEP. This suggests that PEEP could serve as a ventricular assist mechanism in isolated cases of ventricular failure. Heart-lung interaction during mechanical ventilation needs further study.

Multicompartment management of patients with severe traumatic brain injury

Intracranial pressure (ICP) control is a mainstay of traumatic brain injury (TBI) management. However, development of intracranial hypertension (ICH) may be affected by factors outside of the cranial vault in addition to the local effects of the TBI. This review will examine the pathophysiology of multiple compartment syndrome (MCS) and current treatment considerations for patients with TBI given the effects of MCS. Elevated intra-abdominal pressure (IAP) is associated with ICP elevation, and decompressive laparotomy in patients with concurrent elevations in IAP and ICP can reduce ICP. Elevated intrathoracic pressure may be similarly associated with ICP elevation, although the ideal ventilator management strategy for TBI patients when considering MCS is unclear. In MCS, intracranial, intrathoracic and intra-abdominal compartment pressures are interrelated. TBI patient care should include ICP control as well as minimization of intrathoracic and intra-abdominal pressure as clinically possible.

The cerebrovascular response to graded Valsalva maneuvers while standing.

The Valsalva maneuver (VM) produces large and abrupt increases in mean arterial pressure (MAP) at the onset of strain (Phase I), however, hypotension, sufficient to induce syncope, occurs upon VM release (phase III). We examined the effect of VM intensity and duration on middle cerebral artery blood velocity (MCAv) responses. Healthy men (n =10; mean ± SD: 26 ± 4 years) completed 30%, 60%, and 90% of their maximal VM mouth pressure, for 5 and 10 sec (order randomized) while standing. Beat‐to‐beat MCAv and MAP during phase I (peak), at nadir (phase III), and recovery are reported as the change from standing baseline. During phase I, MCAv rose 15 ± 6 cm·s−1 (P <0.001), which was not reliably different between intensities (P =0.11), despite graded increases in MAP (P <0.001; e.g., +12 ± 9 mmHg vs. +35 ± 14 for 5 sec 30% and 90% VM, respectively). During Phase III, the MCAv response was duration‐ (P = 0.045) and intensity dependent (P < 0.001), with the largest decrease observed following the 90% VM (e.g., −19 ± 13 and −15 ± 11 cm·s−1 for 5 and 10 sec VM, respectively) with a concomitant decrease in MAP (P <0.001, −23 ± 11 and −23 ± 9 mmHg). This asymmetric response may be attributable to the differential modulators of MCAv throughout the VM. The mechanical effects of the elevated intrathoracic pressure during phase I may restrain increases in cerebral perfusion via related increases in intracranial pressure; however, during phase III the decrease in MCAv arises from an abrupt hypotension, the extent of which is dependent upon both the duration and intensity of the VM.

Negative pressure pulmonary edema following septoplasty surgery triggering acute subendocardial myocardial in farction

Negative pressure pulmonary edema (NPPE) is defined as fluid transudation into the pulmonary interstitium which occurs as a result of elevated negative intrathoracic pressure caused by the upper respiratory tract obstruction and strong inspiratory effort. NPPE is usually seen during emergence from general anesthesia in the early post-operative period especially after upper respiratory tract surgery. We present a case of a 37-year-old male patient who underwent septoplasty operation and developed NPPE which could not diagnosed and progressed to acute subendocardial myocardial infarction.

Unusual presentation of pericardial effusion

Sir, I read the article on “Unusual presentation of pericardial effusion” by Saseedharan et al., with interest.[1] I have to commend the authors for highlighting well certain salient features of pericardial effusion symptomatology and clinical aspects of cough syncope. But there are some unexplained factors that had been left unattended in the case report. The authors do mention that the predominant feature of this particular case presentation is cough syncope, and they also do mention that this is possibly related to raised intrathoracic pressure. But what is lacking is the clear association with a prominent right hilar shadowing, a cytology positive for metastatic non-small cell carcinoma, and moderate effusions at both pleural cavities along with this pericardial effusion. Even the right supraclavicular node showed a positive cytology for confirming a spreading disease, possibly from a focus in the lung. Any of these could also lead to elevation of intrathoracic pressure, however, transiently, and present with cough syncope. Also noteworthy are the findings on CT scan, showing features of concentric thickening of bronchial tree in the right lower lobe. Even if a metastatic lesion is found during a process of treatment of symptom-inciting condition, it is mandatory that one search for the primary disease to stage the lesion correctly, and ascertain the prognosis along with the treatment pathway. With the moderate effusion as shown by the imaging, it would be difficult to establish this as the actual cause of cough syncope rather than the whole complex of lung disease or pleural effusions. Absence of cardiac tamponade should also alert one to other explanations of the symptoms, and to work up the case in more detail than shown here.

Laughter‐Induced Left Bundle Branch Block

We present the case of a patient with ischemic heart disease and intermittent left bundle branch block, reproducibly induced by laughter. Following treatment of ischemia with successful deployment of a drug-eluting stent, no further episodes of inducible LBBB were seen. Transient ischemia, exacerbated by elevated intrathoracic pressure during laughter, may have contributed to onset of this phenomenon.