Negative pressure pulmonary hemorrhage

Postoperative pulmonary edema and pulmonary hemorrhage following hysteroscopy

BACKGROUND

Hysteroscopic surgery, a minimally invasive technique prevalent in gynecology, exhibits an overall complication rate between 0.22% and 3.7%. Pulmonary bleeding post-hysteroscopy represents an exceedingly rare complication with only three reported cases to date; two involving high-viscosity solutions and one with hypertonicity solutions. Negative-pressure pulmonary hemorrhage, a seldomly encountered and lethal complication, manifests post-upper airway obstruction, with minimal documented cases, none within hysteroscopic procedures.

CASE PRESENTATION

Regarding the case study, a 38-year-old female underwent hysteroscopic surgery and received 1600 milliliters of isosmotic low-viscosity uterine distension media (physiological saline) during the procedure. The patient experienced a transient upper airway obstruction lasting one minute due to anesthetic medication. 1 h after surgery, she exhibited positional coughing, expectorated pinkish diluted sputum, and displayed symptoms of hypoxemia. Physical examination revealed bilateral moist rales in the lung fields, while cardiac auscultation did not detect any abnormal murmurs. Diagnostic procedures included chest CT, echocardiography, and complete blood count. The chest CT illustrated diffusely reticular and patchy ground-glass opacities in both lungs, confirming the diagnosis of pulmonary edema with pulmonary bleeding. Treatment with dexamethasone and furosemide led to rapid improvement, meeting discharge criteria within 24 h post-surgery. Postoperative follow-ups showed no discomfort symptoms in the patient, with normal chest X-ray results.

CONCLUSIONS

In conclusion, the observed upper airway obstruction during hysteroscopic surgery seemingly reduced the safe absorption threshold of isosmotic uterine distension media. Therefore, gynecologists and anesthesiologists should remain vigilant about this potential complication.

Early diagnosis of negative-pressure pulmonary edema presenting as diffuse alveolar hemorrhage using lung ultrasonography -A case report

BACKGROUND

Diffuse alveolar hemorrhage (DAH) is a potentially life-threatening condition that can occur due to a variety of disorders. Hence, rapid diagnosis and prompt initiation of appropriate treatment are imperative.

CASES

A 55-year-old woman with a deep neck infection underwent emergent tonsillectomy. General anesthesia and surgery proceeded uneventfully. Upon transfer to the post-anesthesia care unit, ongoing respiratory distress and occasional expectoration of blood-tinged sputum were noted. Lung ultrasonography (LUS) revealed multiple B-profiles and irregular pleural lines with subpleural consolidations. Emergent bronchoscopy with bronchoalveolar lavage was diagnostic of DAH. She underwent a comprehensive evaluation for rheumatologic and infectious etiologies of DAH, all of which yielded negative results. The patient was managed with steroids and conservative treatment.

CONCLUSIONS

The integration of LUS with clinical information allows for more rapid differentiation of acute respiratory failure causes. Therefore, anesthesiologists' awareness and utilization of LUS findings of DAH can significantly contribute to appropriate management.

Postmortem computed tomography imaging of negative pressure pulmonary edema induced by rice cakes: A case report

Airway obstruction by foreign bodies or laryngospasms often results in negative pressure pulmonary edema (NPPE). NPPE can develop despite the removal of airway obstruction. This is well-known among clinicians, particularly anesthesiologists, emergency physicians, pediatricians, and radiologists. Computed tomography (CT) features of NPPE include diffuse central ground-glass opacities and thickening of the bronchovascular bundles and bronchial walls. NPPE can also occur after strangulation or smothering with a plastic bag, and is sometimes fatal. Nevertheless, no reports of NPPE are available in forensic journals, and forensic practitioners may not be dedicating the necessary attention to this condition. Recently, the use of postmortem CT as an auxiliary imaging modality for autopsies has increased among forensic institutions in Japan. Understanding the mechanisms and CT findings of NPPE will be useful for forensic practitioners. Herein, we present a case wherein the postmortem CT image revealed NPPE resulting from the obstruction of the airway induced by rice cakes.

A Rare Case of Diffuse Alveolar Hemorrhage Caused by Fentanyl Inhalation

Diffuse alveolar hemorrhage (DAH) is a rare but life-threatening pulmonary disorder characterized by blood accumulation in alveolar spaces, often associated with autoimmune diseases and infections. Drug-induced causes of DAH, including inhalation of substances like fentanyl, are emerging concerns. A 40-year-old male with bipolar disorder and polysubstance abuse presented with altered mental status and hemoptysis after inhaling an unknown substance. Physical examination revealed respiratory distress, pinpoint pupils, and severe hypoxemia. Naloxone administration improved his condition. The workup showed negative infection markers, positive fentanyl-specific urine test, and diffuse bilateral opacities on imaging. Bronchoalveolar lavage confirmed DAH with >20% hemosiderin-laden macrophages. Steroid treatment resulted in marked improvement. Drug-induced DAH, such as fentanyl inhalation, should be considered in patients with altered mental status and pulmonary symptoms following substance use. Comprehensive evaluation and targeted treatment are crucial for optimal outcomes.

Pulmonary hemorrhage and associated risk factors among newborns admitted to a tertiary level neonatal unit in Botswana

Introduction

Pulmonary hemorrhage (PH) is a life-threatening complication seen in very sick newborns with high morbidity and mortality. There is little data on the incidence, risk factors, and ultimate survival of newborns with pulmonary hemorrhage in sub-Saharan countries, where the healthcare provision and facility differ in many ways compared to high-income countries. Hence, this study aimed to determine the incidence, identify the risk factors, and describe the outcome of pulmonary hemorrhage in newborns in a low middle income country setting.

Methods and materials

A cohort study with prospective data collection was conducted in a public, tertiary-level hospital in Botswana, the Princess Marina Hospital (PMH). All newborns admitted to the neonatal unit from 1 January 2020 to 31 December 2021 were included in the study. Data were collected using a checklist developed on the RedCap database (https//:ehealth.ub.ac.bw/redcap). The incidence rate of pulmonary hemorrhage was calculated as the number of newborns who had pulmonary hemorrhage per 1,000 newborns in the 2-year period. Group comparisons were made using X² and Student's t-tests. Multivariate logistic regression was used to identify risk factors independently associated with pulmonary hemorrhage.

Result

There were 1,350 newborns enrolled during the study period, of which 729 were male newborns (54%). The mean (SD) birth weight was 2,154(±997.5) g, and the gestational age was 34.3 (±4.7) weeks. In addition, 80% of the newborns were delivered in the same facility. The incidence of pulmonary hemorrhage was 54/1,350 {4% [95% CI (3%-5.2%)]} among the newborns admitted to the unit. The mortality rate in those diagnosed with pulmonary hemorrhage was 29/54 (53.7%). Multivariate logistic regression identified birth weight, anemia, sepsis, shock, disseminated intravascular coagulopathy (DIC), apnea of prematurity, neonatal encephalopathy, intraventricular hemorrhage, mechanical ventilation, and blood transfusion as risk factors independently associated with pulmonary hemorrhage.

Conclusion

This cohort study identified a high incidence and mortality rate of pulmonary hemorrhage in newborns in PMH. Multiple risk factors, such as low birth weight, anemia, blood transfusion, apnea of prematurity, neonatal encephalopathy, intraventricular hemorrhage, sepsis, shock, DIC, and mechanical ventilation, were identified as independently associated risk factors for PH.

[Diffuse alveolar hemorrhage in cannabis smokers. A systematic literature review]

Cannabis is the most widely used illicit psychoactive substance in France. It can be responsible for numerous pulmonary complications, including diffuse alveolar hemorrhage (DAH). The objective of this systematic review of the literature was to present data concerning the relationship between cannabis smoking and DAH, which has rarely been reported in the literature. The review was based on a Medline search covering the 1980-2022 period and utilizing data drawn from 10 articles. DAH diagnosis is based on an association of hemoptysis, anemia and diffuse alveolar opacities on chest radiography with siderophages in the Bronchoalveolar Lavage Fluid (BAL). The 11 patients identified in this review were daily or regular cannabis smokers; in 4 cases they presented recent or recurrent hemoptysis with anemia; imaging revealed diffuse alveolar opacities in 10 of them, while BAL endoscopy highlighted a diffuse hemorrhage in the bronchial tree, and siderophages were observed in 6 cases. While evolution was favorable when cannabis consumption was discontinued, resumption occasioned DAH recurrence, and one patient died. Advice to quit should systematically be accompanied by addictological follow-up.

Research Progress on the Mechanism of Right Heart-Related Pulmonary Edema

Objective. To investigate the mechanisms underlying the development of right heart-associated PE. Background. Right heart-related pulmonary edema (PE) refers to PE resulting from impaired right heart function caused by primary or secondary factors, which is common in critically ill patients. Although the clinical manifestations of different types of right heart-related PE are similar, the pathophysiological changes and treatment methods are significantly different. According to the hemodynamic mechanism, right heart-related PE is primarily classified into two types. One is the increase of right heart flow, including extravascular compression, intravascular compression, cardiac compression, and cardiac decompression. The other type is the abnormal distribution of pulmonary circulation, including obstruction, resistance, pleural decompression, or negative pressure. With the development of hemodynamic monitoring, hemodynamic data not only help us understand the specific pathogenesis of right heart-related PE but also assist us in determining the direction of therapy and enabling individualized treatment. Summary. This article presents a review on right heart-associated PE, with a perspective of hemodynamic analysis, and emphasizes the importance of right heart function in the management of circulation. Understanding the mechanism of right heart-associated PE will not only aid in better monitoring right heart function but also help intensivists make a more accurate identification of various types of PE in the clinic.

Negative-pressure pulmonary Hemorrhaging Due to Severe Obstructive Sleep Apnea

A 24-year-old man with a history of bloody sputum for 6 months was referred to our hospital with suspected alveolar hemorrhaging due to vasculitis. Chest computed tomography showed ground-glass opacities in both lungs, and an examination of his bronchoalveolar lavage fluid showed alveolar hemorrhaging. However, no evidence of vasculitis was found, and subsequent polysomnographic testing confirmed that he had severe obstructive sleep apnea (OSA). Since the alveolar hemorrhaging improved after the initiation of continuous positive airway pressure treatment, the diagnosis was negative-pressure alveolar hemorrhaging due to severe OSA.

Diffuse Alveolar Hemorrhage Associated with Dilated Cardiomyopathy and Sleep Apnea Syndrome

We herein report a case of diffuse alveolar hemorrhage (DAH) associated with dilated cardiomyopathy (DCM) and sleep apnea syndrome (SAS) in a 47-year-old man. The patient exhibited recurring dyspnea and bloody sputum. Chest radiography showed bilateral diffuse infiltrative opacities without pleural effusion. A bronchoscopic analysis of bronchoalveolar lavage fluid revealed hemosiderin-laden macrophages. Based on these findings, he was diagnosed with DAH. Laboratory and pathological findings ruled out the possibility of collagen diseases and vasculitis. Overnight polysomnography revealed concomitant severe obstructive SAS. Treatment with continuous positive-pressure ventilation and pharmacological therapy for DCM prevented recurrence of DAH.

Unilateral pulmonary hemorrhage caused by negative pressure pulmonary edema: A case report

BACKGROUND

Unilateral pulmonary hemorrhage is typically reported in young and healthy men with upper respiratory tract obstruction during anesthesia in special situations. Negative pressure in the lungs is created, resulting in negative pressure pulmonary edema (NPPE).

CASE SUMMARY

A 78-year-old male patient diagnosed with spinal stenosis was admitted to receive a unilateral laminectomy with bilateral decompression. The patient had been diagnosed with hypertension four years earlier and asthma more than 70 years earlier. We experienced a unilateral alveolar hemorrhage associated with NPPE that occurred in a longstanding asthma patient who bit the intubated endotracheal tube for a short period during posture change at the end of surgery. Because diffuse alveolar hemorrhage accompanied by NPPE was caused in this case by airway obstruction in an older patient with asthma without known risk factors, anesthesiologists should be careful not to induce airway irritation during anesthesia awakening in asthma patients.

CONCLUSION

Because diffuse alveolar hemorrhage accompanied by NPPE can occur, anesthesiologists should take care not to induce airway irritation.

As a Rare Reason of Alveolar Consolidation, Negative Pressure Pulmonary Edema: Case Report

In this paper we describe two cases with negative pressure pulmonary edema (NPPE). Excessive negative airway pressures against an obstructed airway has been reported to cause fluid filtration into alveoli and lung edema. The patients are generally young adults without any medical problems. The condition involves central interstitial area of both lungs and is treated by nonnvasive mechanical ventilation and corticosteroids.

Negative Pressure Pulmonary Edema as a Cause of Diffuse Alveolar Hemorrhage in the Newborn

Negative pressure pulmonary edema (NPPE) is a rare entity that can become life threatening. Its development in neonates is very rare, and its presentation as alveolar hemorrhage is uncommon. We report a case of a newborn 23 days old, previously healthy, who presented an episode of choking during breastfeeding. This progressed to acute respiratory failure due to diffuse alveolar hemorrhage. A few hours after admission, the newborn developed refractory hypoxemia, requiring high-frequency oscillatory ventilation and nitric oxide therapy for 24 hours. NPPE was postulated as a diagnosis of exclusion. The newborn recovered completely. NPPE should always be considered in a case with recent obstruction of the upper airway, even in unusual age groups. Sometimes it can manifest as alveolar hemorrhage.

Negative pressure pulmonary edema-related diffuse alveolar hemorrhage associated with Sevoflurane and cigarette smoking

Negative-pressure pulmonary edema (NPPE)-related diffuse alveolar hemorrhage (DAH) is an underdiagnosed clinical entity seen with alveolar capillary damage. The pathophysiology of type I NPPE is generation of a negative pleural pressure against an upper airway obstruction. We suspect this process was facilitated by preexisting alveolar damage with smoking and administration of the irritating and coagulopathic inhaled anesthetic sevoflurane. We present a case of a healthy 31-year-old man who developed postoperative hemoptysis, diffuse ground-glass opacity and infiltrates on computed tomography (CT) of the chest, anemia, and hypoxic respiratory failure. A diagnosis of DAH was made and a serologic workup for systemic disorders including vasculitis and connective tissue diseases was negative. The patient rapidly improved with supportive care and had complete resolution of his bilateral infiltrates on repeat chest x-ray two weeks later. Our literature review identified three cases of DAH in the setting of sevoflurane administration. Our case illustrates the importance of including NPPE-related DAH on the differential of post-operative hemoptysis, especially in association with sevoflurane administration and a history of cigarette smoking.

Diffuse alveolar hemorrhage following sugammadex and remifentanil administration: A case report

RATIONALE

Diffuse alveolar hemorrhage (DAH) is a rare life-threatening condition that accompanies general anesthesia. Negative-pressure pulmonary edema (NPPE) is a rare cause of DAH.

PATIENT CONCERNS

A 25-year-old male patient developed hemoptysis following remifentanil administration by bolus injection with sugammadex at the emergence from general anesthesia.

DIAGNOSIS

Chest x-ray and computed tomography showed DAH.

INTERVENTIONS

Conservative care was provided with 4L of oxygen via nasal prong, 20 mg of Lasix and 2500 mg of tranexamic acid.

OUTCOMES

The patient was discharged uneventfully.

LESSONS

Muscle rigidity by remifentanil and the dissociated reversal of neuromuscular blockade by sugammadex was suspected as the cause of NPPE-related DAH. Therefore, the possibility NPPE-related DAH should be considered when using a bolus of remifentanil and sugammadex during emergence from general anesthesia.

Negative Pressure Pulmonary Hemorrhage after Laryngospasm during the Postoperative Period

Negative pressure pulmonary hemorrhage (NPPH) is an uncommon complication of upper airway obstruction. Severe negative intrathoracic pressure after upper airway obstruction can increase pulmonary capillary mural pressure, which results in mechanical stress on the pulmonary capillaries, causing NPPH. We report a case of acute NPPH caused by laryngospasm in a 25-year-old man during the postoperative period. Causative factors of NPPH include negative pulmonary pressure, allergic rhinitis, smoking, inhaled anesthetics, and positive airway pressure due to coughing. The patient’s symptoms resolved rapidly, within 24 hours, with supportive care.

Postoperative diffuse alveolar haemorrhage: insidious negative pressure or sevoflurane induced?

Negative pressure pulmonary oedema is well described in the literature as an uncommon but recognised complication of general anaesthe sia; negative pressure diffuse alveolar haemorrhage is a rarer consequence. We report a case of massive haemoptysis following elective general anaesthesia using a laryngeal mask airway device and sevoflurane anaesthetic maintenance. The patient had no obvious signs of laryngospasm or other cause of upper airway obstruction perioperatively. We explore the possibility that the haemoptysis was caused by clinically unapparent negative pressure generation, but also ask whether the anaesthetic agent should be considered as a culprit.

Endotracheal tube obstruction with a blood clot following aspiration of rumen contents in a reindeer

Summary

An apparently otherwise healthy female reindeer was anaesthetised for open reduction and fixation of a hip luxation. The animal developed ruminal bloat which was treated with passage of an orogastric tube that was left indwelling during the procedure. A fluid inspiratory noise was audible two hours after decompression, and clear fluid was suctioned from the airway. It showed no other signs of regurgitation and aspiration of rumen contents intraoperatively, and did not develop obvious respiratory compromise while mechanically ventilated. In recovery, the deer became apnoeic and cyanotic and died suddenly within minutes of being positioned in the recovery box. Just before dying, it coughed a large blood clot out of the endotracheal tube (ETT) . Additional clots were found partially obstructing the ETT lumen once extubated postmortem. Evidence of aspiration was detected at postmortem examination, which also identified pulmonary haemorrhage.

The role of Src & ERK1/2 kinases in inspiratory resistive breathing induced acute lung injury and inflammation

Background

Inspiratory resistive breathing (IRB), a hallmark of obstructive airway diseases, is associated with large negative intrathoracic pressures, due to strenuous contractions of the inspiratory muscles. IRB is shown to induce lung injury in previously healthy animals. Src is a multifunctional kinase that is activated in the lung by mechanical stress. ERK1/2 kinase is a downstream target of Src. We hypothesized that Src is activated in the lung during IRB, mediates ERK1/2 activation and IRB-induced lung injury.

Methods

Anaesthetized, tracheostomized adult rats breathed spontaneously through a 2-way non-rebreathing valve. Resistance was added to the inspiratory port to provide a peak tidal inspiratory pressure of 50% of maximum (inspiratory resistive breathing). Activation of Src and ERK1/2 in the lung was estimated during IRB. Following 6 h of IRB, respiratory system mechanics were measured by the forced oscillation technique and bronchoalveolar lavage (BAL) was performed to measure total and differential cell count and total protein levels. IL-1b and MIP-2a protein levels were measured in lung tissue samples. Wet lung weight to total body weight was measured and Evans blue dye extravasation was estimated to measure lung permeability. Lung injury was evaluated by histology. The Src inhibitor, PP-2 or the inhibitor of ERK1/2 activation, PD98059 was administrated 30 min prior to IRB.

Results

Src kinase was activated 30 min after the initiation of IRB. Src inhibition ameliorated the increase in BAL cellularity after 6 h IRB, but not the increase of IL-1β and MIP-2a in the lung. The increase in BAL total protein and lung injury score were not affected. The increase in tissue elasticity was partly inhibited. Src inhibition blocked ERK1/2 activation at 3 but not at 6 h of IRB. ERK1/2 inhibition ameliorated the increase in BAL cellularity after 6 h of IRB, blocked the increase of IL-1β and returned Evans blue extravasation and wet lung weight to control values. BAL total protein and the increase in elasticity were partially affected. ERK1/2 inhibition did not significantly change total lung injury score compared to 6 h IRB.

Conclusions

Src and ERK1/2 are activated in the lung following IRB and participate in IRB-induced lung injury.

Post-obstructive pulmonary edema from aspirated nuts

OBJECTIVES

Post-obstructive pulmonary edema is thought to occur from hemodynamic changes secondary to forced inspiration against the closed airway due to acute or chronic airway obstruction. We report a case of a 13 month-old boy who developed pulmonary edema from aspirated foreign body, nuts.

METHODS

He underwent emergency bronchoscopy to confirm the clinical diagnosis of aspirated nuts in the trachea and nuts were removed endoscopically. His trachea was then intubated and he was mechanically ventilated with oxygen.

RESULTS

He developed florid pulmonary edema early in the course with tracheal obstruction and during endoscopic removal of nuts. After removal of obstruction he was ventilated mechanically and pulmonary edema cleared rapidly.

CONCLUSIONS

Aspirated nuts obstructing trachea can induce obstructive pulmonary edema. Early recognition of foreign body obstruction based on clinical history and its removal resolved pulmonary edema.

Clinical Features of Patients with Diffuse Alveolar Hemorrhage due to Negative-Pressure Pulmonary Edema

PURPOSE

Diffuse alveolar hemorrhage (DAH) with negative-pressure pulmonary edema (NPPE) is an uncommon yet life-threatening condition. We aimed at describing the circumstances, clinical, radiological, and bronchoscopic features, as well as the outcome of patients with NPPE-related DAH.

METHODS

We performed a retrospective, observational cohort study, using data prospectively collected over 35 years in an intensive care unit (ICU).

RESULTS

Of the 149 patients admitted for DAH, we identified 18 NPPE episodes in 15 patients, one admitted four times for recurrent NPPE-related DAH. The patients were primarily young, male, and athletic. The NPPE setting was postoperative (n = 12/18, 67%) or following generalized tonic-clonic seizures (n = 6/18, 33%). Hemoptysis was almost constant (n = 17/18, 94%), yet rarely massive (>200 cc, n = 1/18, 6%), with anemia observed in 10 (56%) episodes. The DAH triad (hemoptysis, anemia, and pulmonary infiltrates) was observed in 50% of episodes (n = 9/18), and acute respiratory failure in 94% (n = 17/18). Chest computed tomography revealed diffuse bilateral ground glass opacities (n = 10/10, 100%), while bronchoscopy detected bilateral hemorrhage (n = 12/12, 100%) and macroscopically bloody bronchoalveolar lavage, with siderophage absence in most (n = 7/8, 88%), indicating acute DAH. While one episode proved fatal, the other 17 recovered rapidly, with a mean ICU stay lasting 4.6 (2-15) days. Typically, the evolution was rapidly favorable under supportive care.

CONCLUSION

NPPE-related DAH is a rare life-threatening condition occurring primarily after tonic-clonic generalized seizure or generalized anesthesia. Clinical circumstances are a key to its diagnosis. Early diagnosis and recognition likely allow for successful management of this potentially serious complication, whereas ictal-DAH appears ominous in epileptic patients.

A Case Report of Cannabis Induced Hemoptysis

As the principal route of marijuana use is by inhalation, potential harmful consequences on pulmonary structure and function can be anticipated. Here, we present a case of hemoptysis attributed to smoking cannabis in a 38-year-old man. The patient experienced an episode of hemoptysis and shortness of breath immediately after smoking marijuana. Chest radiograph and computed tomography (CT) scans of the chest showed bilateral diffuse ground-glass opacities. A fiber optic bronchoscopy confirmed bilateral diffuse bleeding from respiratory tract. Additional evaluation of hemoptysis indicated no infection or immunological responses. Urine toxicology was positive for cannabis. Chronic marijuana smoking causes visible and microscopic injury to the larger airways responsible for symptoms or chronic bronchitis. We review the beneficial and deleterious effects of marijuana and describe a case of significant hemoptysis attributed to smoking marijuana. In addition to other respiratory complications of marijuana use, physicians should educate their patients about this potentially lethal effect of marijuana smoking in the form of hemoptysis.

A Case of Acute Upper Airway Obstruction in a Pediatric Hemophilia A Patient Because of Spontaneous Retropharyngeal Hemorrhage

We report a rare case of acute upper airway obstruction caused by spontaneous retropharyngeal hemorrhage as a result of hemophilia A in a 16-year-old pediatric patient who routinely received factor VIII replacement. Initial diagnosis was delayed because the patient presented with symptoms, such as throat pain and odynophagia, similar to those of common benign upper airway infections. Within 2 days of the initial presentation of symptoms, the patient went into respiratory failure as a result of retropharyngeal hemorrhage. The possibility of spontaneous retropharyngeal or epiglottic hemorrhage or hematoma should be considered as a cause of rapidly progressing odynophagia and dyspnea by hemophilia patients.

Frequency of hypoxic events in patients on a mechanical ventilator

Background:

Mechanical ventilation is an important tool in the management of respiratory failure in the critically ill patient. Although mechanical ventilation can be a life-saving intervention, it is also known to carry several side-effects and risks. Adequate oxygenation is one of the primary goals of mechanical ventilation. However, while on mechanical ventilation, patients frequently experience hypoxic events resulting from various causes, which need to be properly evaluated and treated.

Materials and Methods:

Data were obtained by prospectively reviewing all intensive care admissions during the period from March 2009 to March 2010 at a 651-bed urban medical center. Patients who developed hypoxemia (oxygen saturation ≤88% and a PaO₂≤60 torrs) while on mechanical ventilation were investigated for the cause of hypoxic event.

Results:

During the study period, 955 patients required mechanical ventilation from which 79 developed acute hypoxia. The causes of acute hypoxia in decreasing order of occurrences were pulmonary edema, atelectasis, pneumothorax, pneumonia, ARDS, endotracheal tube malfunction, airway bleeding, and pulmonary embolism.

Conclusions:

Appropriate evaluation of all hypoxic events must begin at the bedside. A step-by-step approach must include a thorough physical examination. Evaluation of the endotracheal tube can immediately reveal dislodgement, bleeding, and secretions. Correlation of physical examination findings with those on chest radiograph is essential. Each hypoxic event requires a different intervention depending on its etiology. Instead of simply increasing the fraction of oxygen in the inspired air to overcome hypoxia, a concerted effort in appropriate problem solving can reduce the likelihood of an incorrect diagnosis and management response.

L-Cysteine ethyl ester reverses the deleterious effects of morphine on, arterial blood-gas chemistry in tracheotomized rats

This study determined whether the membrane-permeable ventilatory stimulant, L-cysteine ethylester (L-CYSee), reversed the deleterious actions of morphine on arterial blood-gas chemistry in isoflurane-anesthetized rats. Morphine (2 mg/kg, i.v.) elicited sustained decreases in arterial blood pH, pO₂ and sO₂, and increases in pCO₂ (all responses indicative of hypoventilation) and alveolar-arterial gradient (indicative of ventilation-perfusion mismatch). Injections of L-CYSee (100 μmol/kg, i.v.) reversed the effects of morphine in tracheotomized rats but were minimally active in non-tracheotomized rats. L-cysteine or L-serine ethylester (100 μmol/kg, i.v.) were without effect. It is evident that L-CYSee can reverse the negative effects of morphine on arterial blood-gas chemistry and alveolar-arterial gradient but that this positive activity is negated by increases in upper-airway resistance. Since L-cysteine and L-serine ethylester were ineffective, it is evident that cell penetrability and the sulfur moiety of L-CYSee are essential for activity. Due to its ready penetrability into the lungs, chest wall muscle and brain, the effects of L-CYSee on morphine-induced changes in arterial blood-gas chemistry are likely to involve both central and peripheral sites of action.

Negative pressure pulmonary edema after laparoscopic donor nephrectomy

Although usually a self-limiting phenomenon, negative pressure pulmonary edema requires immediate re-establishment of the airway, adequate oxygenation, and application of a positive airway.

Introduction:

Laparoscopic donor nephrectomy is associated with a 10% chance of morbidity and a 0.03% mortality rate. We present a case of negative pressure pulmonary edema (NPPE) in a healthy subject immediately following a laparoscopic donor nephrectomy. In this report, we will use the case to review the complications of NPPE and to illustrate its management.

Case Description:

A healthy 19-y-old male presented at our institution as a living-related donor for left laparoscopic donor nephrectomy. Following the surgery, the patient was reintubated and kept in the intensive care unit secondary to NPPE. The patient experienced an uneventful postoperative course and was subsequently discharged.

Discussion:

Although a self-limiting phenomenon, mainstay NPPE therapy requires immediate re-establishment of the airway, adequate oxygenation, and application of positive airway pressure.

Negative pressure pulmonary edema with laryngeal mask airway use: Recognition, pathophysiology and treatment modalities

Negative pressure pulmonary edema (NPPE) following the use of the laryngeal mask airway (LMA) is an uncommon and under-reported event. We present a case of a 58-year-old male, who developed NPPE following LMA use. After biting vigorously on his LMA, the patient developed stridor upon emergence, with concurrent appearance of blood-tinged, frothy sputum and pulmonary edema. He subsequently required three days of mechanical ventilation. After discontinuation of mechanical ventilation the patient continued to require additional pulmonary support using continuous positive airway pressure, with a full facemask, to correct the persistent hypoxemia. His roentgenographic findings demonstrated an accelerated improvement with judicious administration of intravenous furosemide.

Delayed presentation: negative pressure pulmonary hemorrhage

Negative pressure pulmonary hemorrhage (NPPH) is a rare, life-threatening complication that develops after an acute upper airway obstruction. A 26 year old, healthy African-American man with no underlying lung disease developed negative pressure pulmonary edema and subsequently NPPH during recovery from general anesthesia for elective spine surgery. Diagnostic bronchoscopy confirmed an alveolar source of the bleeding. Clinical improvement was quick with supportive care in the medical intensive care unit.

Diffuse alveolar hemorrhage in immunocompetent patients: etiologies and prognosis revisited

BACKGROUND

Diffuse alveolar hemorrhage (DAH) represents a diagnostic challenge of acute respiratory failure. Prompt identification of the underlying cause of DAH and initiation of appropriate treatment are required in order to prevent acute respiratory failure and irreversible loss of renal function. More than 100 causes of DAH have been reported. However, the relative frequency and the differential presentation of those causes have been poorly documented, as well as their respective prognosis.

METHODS

We retrospectively reviewed the charts of 112 consecutive patients hospitalized for DAH in a tertiary referral center over a 30-year period.

RESULTS

Twenty-four causes of DAH were classified into four etiologic groups: immune (n = 39), congestive heart failure (CHF; n = 33), miscellaneous (n = 26), and idiopathic DAH (n = 14). Based on this classification, clinical and laboratory features of DAH differed on hospital admission. Patients with immune DAH had more frequent pulmonary-renal syndrome (p < 0.001), extra-pulmonary symptoms (p < 0.01), and lower blood hemoglobin level than others (p < 0.001). Patients with CHF-related DAH were older and received more anticoagulant treatments than others (p < 0.05). Those with miscellaneous causes of DAH exhibited a shorter prodromal phase (p < 0.001) and had more frequent hemoptysis >200 mL (p < 0.05). Patients with idiopathic DAH had more bronchoalveolar lavage siderophages (p < 0.01). In-hospital mortality was 24.1%, ranging from 7.1% in patients with idiopathic DAH to 36.4% in those with CHF.

CONCLUSIONS

Arbitrary classification of DAH in four etiologic groups gives the opportunity to underline distinct presentations and outcomes of various causes of DAH.

Genetically determined heterogeneity of lung disease in a mouse model of airway mucus obstruction

Mucus clearance is an important airway innate defense mechanism. Airway-targeted overexpression of the epithelial Na(+) channel β-subunit [encoded by sodium channel nonvoltage gated 1, beta subunit (Scnn1b)] in mice [Scnn1b-transgenic (Tg) mice] increases transepithelial Na(+) absorption and dehydrates the airway surface, which produces key features of human obstructive lung diseases, including mucus obstruction, inflammation, and air-space enlargement. Because the first Scnn1b-Tg mice were generated on a mixed background, the impact of genetic background on disease phenotype in Scnn1b-Tg mice is unknown. To explore this issue, congenic Scnn1b-Tg mice strains were generated on C57BL/6N, C3H/HeN, BALB/cJ, and FVB/NJ backgrounds. All strains exhibited a two- to threefold increase in tracheal epithelial Na(+) absorption, and all developed airway mucus obstruction, inflammation, and air-space enlargement. However, there were striking differences in neonatal survival, ranging from 5 to 80% (FVB/NJ<BALB/cJ<C3H/HeN<C57BL/6N), which correlated with the incidence of upper airway mucus plugging and the levels of Muc5b in bronchoalveolar lavage. The strains also exhibited variable Clara cell necrotic degeneration in neonatal intrapulmonary airways and a variable incidence of pulmonary hemorrhage and lung atelectasis. The spontaneous occurrence of a high surviving BALB/cJ line, which exhibited delayed onset of Na(+) hyperabsorption, provided evidence that: 1) air-space enlargement and postnatal death were only present when Na(+) hyperabsorption occurred early, and 2) inflammation and mucus obstruction developed whenever Na(+) hyperabsorption was expressed. In summary, the genetic context and timing of airway innate immune dysfunction critically determines lung disease phenotype. These mouse strains may be useful to identify key modifier genes and pathways.

Pulmonary hemorrhage: a rare complication of opioid overdose

Children and adolescents with pulmonary hemorrhage are infrequently encountered in the emergency department (ED). We describe a case of a 16 year-old boy who presented to a pediatric ED with pulmonary hemorrhage and respiratory distress. The patient's unusual initial presentation resulted in the consideration of a broad differential diagnosis for his symptoms, including traumatic, neurological, respiratory, and toxicological causes. After resuscitation in the ED, a prolonged admission, and extensive testing, no cause could be found other than severe opioid toxicity. This case illustrates a rare, life-threatening presentation of opiod toxicity in a healthy adolescent and underlines the potentially serious nature of such exposures.

Recurrent negative pressure pulmonary edema

An African-American man, aged 34 years, underwent an elective uncomplicated right wrist laceration repair while under general anesthesia. Following extubation, the patient developed hypoxemia, tachypnea, shortness of breath, pulmonary rales, frothy sputum, decreased oxygen saturation, and evidence of upper airway obstruction. Chest radiograph showed pulmonary edema. The patient was diagnosed with post-extubation pulmonary edema (aka. negative pressure pulmonary edema [NPPE]) and was treated with intravenous furosemide and oxygen therapy; he improved remarkably within a few hours. Once stabilized, the patient described a similar episode 10 years earlier following surgery for multiple gunshot wounds. Negative pressure pulmonary edema following tracheal extubation is an uncommon (0.1%) and life-threatening complication of patients undergoing endotracheal intubation and general anesthesia for surgical procedures. The common pattern in these cases is the occurrence of an episode of airway obstruction upon emergence from general anesthesia, usually caused by laryngospasm. Patients who are predisposed to airway obstruction may have an increased risk of airway complications upon extubation after general anesthesia. Prevention and early relief of upper airway obstruction should decrease incidence. Recurrent NPPE has not been previously described in the literature. Herein, we describe the first case of recurrent NPPE in the same patient following extubation.

Negative-pressure acute tracheobronchial hemorrhage and pulmonary edema

Negative-pressure pulmonary edema is a well-known complication of an acute upper airway obstruction, which may rarely present as acute alveolar hemorrhage in cases of severe capillary stress failure. Hemorrhage from the central airways has also been reported as a rare manifestation of acute tracheobronchial injury, associated with severe disruption of the bronchial vasculature due to highly negative inspiratory pressure. In this clinical report, we describe a case of both acute tracheobronchial and alveolar hemorrhage in a young man, occurring immediately after extubation due to laryngospasm, diagnosed by bronchoscopy with bronchoalveolar lavage (BAL), measurement of the pulmonary edema fluid/plasma protein ratio, and by thoracic computed tomography (CT) scan. We propose that the patient experienced severe postobstructive negative-pressure pulmonary edema, related to increased permeability of the alveolar capillary membrane and a parallel loss of integrity of the bronchial vascular network. Our findings suggest that both changes in the bronchial circulation and mechanical stress failure of the more distal alveolar-capillary system may be induced by severe and acute upper-airway obstruction.

Pulmonary hemorrhage accompanied with pulmonary edema induced by endotracheal tube occlusion in a child: A case report

Negative pressure induced pulmonary edema due to upper airway obstruction is a well-recognized problem. However, negative pressure pulmonary hemorrhage is extremely uncommon. We report a child who developed negative pressure pulmonary hemorrhage following acute airway obstruction caused by clench of endotracheal tube during emergence of anesthesia. The patient was treated with positive pressure ventilation and frequent tracheal suction. Hemorrhage from endotracheal tube was gradually decreased after 4 hours. The patient was extubated after 7 hours.