Objective: To present the pulmonary histopathological alterations found in the autopsies of patients with acute respiratory failure (ARF) and determine whether underlying diseases and certain associated risk factors increase the incidence of these histopathological patterns. Methods: Final autopsy reports were reviewed, and 3030 autopsies of patients > 1 year of age with an underlying disease and associated risk factors were selected. All had developed diffuse infiltrates and died of ARF-related pulmonary alterations. Results: The principal pulmonary histopathological alterations resulting in immediate death were diffuse alveolar damage (DAD), pulmonary edema, lymphocytic interstitial pneumonia (LIP) and alveolar hemorrhage. The principal underlying diseases were AIDS, bronchopneumonia, sepsis, liver cirrhosis, pulmonary thromboembolism, acute myocardial infarction (AMI), cerebrovascular accident, tuberculosis, cancer, chronic kidney failure and leukemia. The principal associated risk factors were as follows: age ≥ 50 years; arterial hypertension; congestive heart failure; chronic obstructive pulmonary disease; and diabetes mellitus. These risk factors and AIDS correlated with a high risk of developing LIP; these same risk factors, if concomitant with sepsis or liver cirrhosis, correlated with a risk of developing DAD; thromboembolism and these risk factors correlated with a risk of developing alveolar hemorrhage; these risk factors and AMI correlated with a risk of developing pulmonary edema. Conclusion: Pulmonary findings in patients who died of ARF presented four histopathological patterns: DAD, pulmonary edema, LIP and alveolar hemorrhage. Underlying diseases and certain associated risk factors correlated positively with specific histopathological findings on autopsy.

Keywords: Respiratory insufficiency; Autopsy; Lung diseases, interstitial; Pulmonary edema; Hemorrhage.

Recent studies suggest that non-invasive positive pressure ventilation (NPPV) improves clinical signs and gas exchange, apart from avoiding the need for endotracheal intubation in selected patients with acute respiratory failure. In this prospective, open trial in the Intensive Care Unit (Hospital Universitário da Universidade Federal de Juiz de Fora), the authors evaluated the efficacy and security of using NPPV in patients with acute respiratory failure. Twenty-five patients with clinical or gasometric diagnosis of acute respiratory failure (respiratory rate > 25 breaths/min, accessory muscle use, PaO2 < 60 mmHg, PaCO2 > 50 mmHg after supplemental oxygen) received NPPV. Fifteen patients (60%) were successfully ventilated with NPPV, avoiding the tracheal intubation. After two hours with NPPV, the respiratory rate was reduced (from 36 ± 2 breaths/min to 26 ± 1 breaths/min, p < 0.01) and the PaO2 increased (from 76 ± 6 mmHg to 100 ± 12 mmHg, p < 0.05). Among the patients with hypercapnia, after two hours, the PaCO2 decreased (from 60 ± 2 mmHg to 49 ± 3 mmHg, p < 0.05). Four patients (16%) presented complications with facial skin necrosis, but only one had the NPPV stopped. Among the patients who did not respond to the method, three did not adapt to the NPPV and seven had it interrupted because of clinical deterioration. The authors conclude that NPPV is a safe option that can be used to treat selected patients with acute respiratory failure.

Objective: To evaluate the effects of non-invasive positive pressure ventilation (NIPPV) on acute respiratory failure and to identify the factors associated with its failure or success. Patients and methods: This open and prospective study analyzed 60 episodes of NIPPV use in 53 patients with respiratory failure. Results: In 37 occasions (62%), the patients were successfully ventilated with NIPPV (Success Group, SG) whereas in 23 episodes (38%) intubation was necessary (Failure Group, FG). FG patients showed a higher Apache II score (30.4 ± 9 versus 22.2 ± 8, p = 0.001). The use of NIPPV reduced respiratory rate after 2 hs. This reduction was less evident in FG (from 33 ± 9 to 30 ± 8 bpm, p = 0.094) than in SG (from 39 ± 11 to 28 ± 9 bpm, p < 0.001). PaO2 increased from 62 ± 22 to 101 ± 65 mmHg, (p < 0.001) with no differences between groups. Among patients with hypercapnia, PaCO2 level decreased in SG (from 76 ± 20 to 68 ± 21mmHg, p = 0.032) but not in FG (from 89 ± 23 to 93 ± 40mmHg, p = 0.54). Arterial pH increased in SG (from 7.25 ± 0.10 to 7.34 ± 0.11, p = 0.007) and not in FG (from 7.24 ± 0.07 to 7.21 ± 0.12, p = 0.48). NIPPV was used for longer in SG (3.4 ± 2.5 versus 2.3 ± 2 days, p = 0.003). Higher IPAP levels were used in SG (13.2 ± 3 versus 11 ± 4cmH2O, p = 0.02). The 10 patients (17%) who died, all belonged to FG. Skin lesions at the site of mask contact was the most common complication of NIPPV (5, 8%). NIPPV was efficient in treating acute respiratory failure in 2/3 of patients. The factors associated with failure were: greater severity of the illness, smaller reduction in the respiratory rate, no improvement of respiratory acidosis in 2 h and use of lower IPAP levels. The high mortality rate observed in FG (10, 43%) justifies efforts to optimize NIPPV implementation and to recognize its failure, as early as possible, in order to avoid delays in endotracheal intubation.

Keywords: Non-invasive positive pressure ventilation. Respiratory failure. Apache II. Hypercapnia.

Objective: To determine the prevalence of nosocomial pneumonia in autopsies at a public university hospital; to identify the risk factors for nosocomial pneumonia and the potential prognostic factors associated with fatal nosocomial pneumonia and with fatal aspiration pneumonia; and to determine whether anatomopathological findings correlate with nosocomial pneumonia or aspiration pneumonia. Methods: A retrospective study involving 199 autopsied patients, older than 1 year of age, who had been admitted to the São Paulo State University Botucatu School of Medicine Hospital das Clínicas and died of nosocomial pneumonia (underlying or contributing cause), between 1999 and 2006. Demographic, clinical and anatomopathological variables were tested regarding their association with the outcomes (fatal nosocomial pneumonia and fatal aspiration pneumonia). The significant variables were analyzed using multivariate analysis. Results: The mean age was 59 ± 19 years. The prevalence of nosocomial pneumonia in autopsies was 29%, and the disease was the cause of death in 22.6% of the autopsied patients. Fatal nosocomial pneumonia correlated with the following anatomopathological findings: tobacco‑associated structural lesions (OR = 3.23; 95% CI: 1.26-2.95; p = 0.02) and bilateral pneumonia (OR = 3.23; 95% CI: 1.26-8.30; p = 0.01). None of the variables were found to be significantly associated with fatal aspiration pneumonia. Conclusions: In our sample, there was a high prevalence of nosocomial pneumonia, which was responsible for almost 25% of all of the deaths. Smoking-related structural lesions and bilateral pneumonia all favored mortality. These findings corroborate the results of various clinical studies on nosocomial pneumonia.

Keywords: Autopsy; Risk factors; Prognosis; Pneumonia, aspiration; Pneumonia/mortality.

Objective: To compare the American-European Consensus Conference (AECC) definition of acute respiratory distress syndrome (ARDS) to autopsy findings. Methods: All patients who died in the intensive care unit of the Federal University of Juiz de Fora University Hospital between 1995 and 2003 and were submitted to autopsy were included in the study. Patient clinical charts were reviewed to establish whether cases met the AECC criteria for a diagnosis of ARDS, histologically defined as the presence of diffuse alveolar damage (DAD). Results: During the study period, 592 patients died, and 22 were submitted to autopsy. Of those 22 patients, 10 (45%) met the AECC criteria, and 7 (32%) met the histopathological criteria for DAD. The AECC clinical criteria presented a sensitivity of 71% (95%CI: 36-92%) and a specificity of 67% (95%CI: 42-85%). The positive and negative predictive values were, respectively, 50 and 83%, whereas the positive and negative likelihood ratios were, respectively, 2.33 and 0.47. The histopathological findings in the 5 patients who met AECC criteria but did not present DAD were pneumonia (n = 2), pulmonary embolism (n = 1), tuberculosis (n = 1), and cryptococcosis (n = 1). Conclusion: The accuracy of the AECC definition of ARDS was godless than satisfactory. Due to the low positive predictive value and the low positive likelihood ratio, other hypotheses must be considered when ARDS is suspected.

Keywords: Respiratory distress syndrome, adult; Diagnostic Techniques and Procedures; Autopsy.

Objective: To describe and analyze clinical symptoms and spirometric alterations of patients with chronic obstructive pulmonary disease (COPD) and history of exposure to wood and tobacco smoke. Methods: We retrospectively evaluated data related to 170 patients distributed into 3 groups: 34 exposed only to wood smoke, 59 patients exposed only to tobacco smoke and 77 patients exposed to both. Results: The groups did not differ significantly in terms of age (p = 0.225) or degree of exposure, considering each type of exposure in isolation or in combination (p = 0.164 and p = 0.220, respectively). Females predominated in the group exposed to wood smoke. There were no differences among the groups regarding respiratory symptoms (p > 0.05), and moderate dyspnea predominated in the three groups (p = 0.141). The group exposed to wood smoke presented higher percentages of forced expiratory volume in one second/forced vital capacity ratio and of forced expiratory volume in one second (p < 0.05). Positive results on bronchodilator testing occurred more frequently in the group exposed to tobacco smoke. The percentage of severe and extremely severe obstruction was significantly higher in the group exposed to tobacco smoke (44.1%) than in that exposed to wood smoke (11.8%; p = 0.006). Conclusions: Respiratory symptoms and pulmonary function alterations consistent with COPD were observed in the groups of patients exposed to wood smoke. However, those alterations were not as significant as the alterations observed in the groups exposed to tobacco smoke. This study emphasizes the importance of prospective studies in evaluating the risk of wood-smoke-related COPD in Brazil, as well as the need for preventive measures in this area.

Keywords: Pulmonary disease, chronic obstructive; Smoking; Air pollution, indoor; Smoke.

The goal of this paper is to review the use of CT scan in acute respiratory failure (ARF), acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The most important papers studying CT in ARF, published in English language literature, were found in Medline. The use of CT in patients with ARF let allowed the authors to proceed to a qualitative evaluation of lung morphology looking for diffuse an/or localized hyperdensities, and for other concomitant abnormalities (pleural effusion, pneumothorax). It is also possible to evaluate lung density histograms and calculate the gas-tissue ratio within the lungs. Likewise, one can also calculate total and regional lung volumes (aerated, poorly-aerated, non-aerated, and overdistension volumes). Knowing those volumes it is possible to quantify alveolar recruitment and overdistension due to ventilatory strategies as the use of different positive end expiratory pressure (PEEP) levels.

Keywords: Acute lung injury. Acute respiratory distress syndrome.

Background: Pulmonary thromboembolism (PTE) is still an enigmatic disorder in many epidemiological and clinical features, remaining one of the most commonly misdiagnosed disorders. Objective: To describe the prevalence and pathological findings of PTE in a series of autopsies, to correlate these findings with underlying diseases, and to verify the frequency of PTE clinically suspected before death. Method: The reports on 5261 consecutive autopsies performed from 1979 to 2002 in a Brazilian tertiary referral medical school were reviewed for a retrospective study. From the medical records and autopsy reports of the patients found with macroscopically and/or microscopically documented PTE, were gathered data on demographics, underlying diseases, antemortem suspicion of PTE, and probable PTE site of origin. Results: The autopsy rate was 42.0% and PTE was found in 544 patients. In 225 cases, PTE was the main cause of death (fatal PTE). Infections (p=0.0003) were associated with nonfatal PTE and trauma (p=0.007) with fatal PTE. The rate of antemortem unsuspected PTE was 84.6% and 40.0% of these patients presented fatal PTE. Diseases of the circulatory system (p=0.0001), infections (p<0.0001), diseases of the digestive system (p=0.0001), neoplasia (p=0.024) and trauma (p=0.005) were associated with unsuspected PTE. The most frequent PTE site of origin was the lower limbs (48.9%). Probable PTE sites of origin such as right-sided cardiac chambers (p=0.012) and pelvic veins (p=0.015) were associated with fatal PTE. Conclusion: A large number of cases do not have antemortem suspicion of PTE. Special attention should be paid to the possibility of PTE in patients with diseases of the circulatory system, infections, diseases of the digestive system, neoplasia, and trauma.

Keywords: Autopsy. Epidemiology. Pulmonary Thromboembolism.

The goal of this paper is to review the use of pressure-volume (P-V) curves or compliance curves in patients with acute respiratory failure (ARF) - acute lung injury (ALI), and acute respiratory distress syndrome (ARDS). The most important papers published in English language literature concerning P-V curves in ARF were found in Medline and reviewed. Ideally, recommendation is made to calculate P-V curves in all patients with ARF in order to achieve adequate monitoring and management considering data obtained from the curves, such as lower inflexion point, upper inflexion point, and static compliance. The methods used to obtain P-V curves are supersyringe, multiple inspiratory occlusions and continuous flow. All of them are similar if low continuous flow is used and if care is taken to allow lung emptying and to avoid intrinsic PEEP (positive end expiratory pressure) before accomplishing the curves. In this way continuous flow can be a simple, inexpensive, secure and reliable method to be carried out at bedside in order to obtain P-V curves that allow for a better monitoring and management of patients with ARF.

Keywords: Acute lung injury. Acute respiratory distress syndrome. Pressure-volume curves.

Objective: To evaluate pulmonary function and respiratory muscle strength in chronic renal failure patients, correlating these variables with hemodialysis-related weight fluctuation; to study the correlation between the duration of hemodialysis and potential respiratory alterations. Methods: Seventeen patients (median age, 47 years; interquartile range, 41-52 years), submitted to three weekly hemodialysis sessions for a median of 27 months (interquartile range, 14-55) were evaluated. Twelve of the patients were male. The patients underwent spirometry. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured prior to and after the first hemodialysis session of the week. Body weight was quantified prior to and after each of the three weekly sessions. Results: Before the first hemodialysis session of the week, 8 patients presented mild restrictive defect, which normalized after the session in 2 of those patients. After dialysis, there was a significant increase in forced vital capacity (p = 0.02) and a significant decrease in body weight (p = 0.0001). Weight fluctuation over 3 days without hemodialysis tended to correlate with the variation in forced vital capacity in the first weekly session (r = 0.47; p = 0.055). Duration of hemodialysis correlated with predialysis MIP (r = −0.3; p = 0.03) and MEP (r = −0.63; p = 0.006). Conclusions: More pronounced weight gain in the interdialytic period is associated with worsening of lung function, which is almost fully reversible by hemodialysis. In addition, longer duration of hemodialysis is associated with decreased respiratory muscle strength.

Keywords: Spirometry; Respiratory muscles/physiopathology; Kidney failure, chronic; Renal dialysis.

Objective: To assess the feasibility of using a new helmet interface for CPAP, designated ELMO, to treat COVID-19-related acute hypoxemic respiratory failure (AHRF) outside the ICU. Methods: This was a proof-of-concept study involving patients with moderate to severe AHRF secondary to COVID-19 admitted to the general ward of a public hospital. The intervention consisted of applying CPAP via the ELMO interface integrated with oxygen and compressed air flow meters (30 L/min each) and a PEEP valve (CPAP levels = 8-10 cmH2O), forming the ELMOcpap system. The patients were monitored for cardiorespiratory parameters, adverse events, and comfort. Results: Ten patients completed the study protocol. The ELMOcpap system was well tolerated, with no relevant adverse effects. Its use was feasible outside the ICU for a prolonged amount of time and was shown to be successful in 60% of the patients. A CPAP of 10 cmH2O with a total gas flow of 56-60 L/min improved oxygenation after 30-to 60-min ELMOcpap sessions, allowing a significant decrease in estimated FIO2 (p = 0.014) and an increase in estimated PaO2/FIO2 ratio (p = 0.008) within the first hour without CO2 rebreathing. Conclusions: The use of ELMOcpap has proven to be feasible and effective in delivering high-flow CPAP to patients with COVID-19-related AHRF outside the ICU. There were no major adverse effects, and ELMO was considered comfortable. ELMOcpap sessions significantly improved oxygenation, reducing FIO2 without CO2 rebreathing. The overall success rate was 60% in this pilot study, and further clinical trials should be carried out in the future. (ClinicalTrials.gov identifier: NCT04470258 [http://www.clinicaltrials.gov/])

Keywords: Pneumonia; SARS-CoV-2; COVID-19; Respiratory protective devices; Continuous positive airway pressure; Noninvasive ventilation.

Eosinophilia-myalgia syndrome was described in 1989 in patients who presented progressive and incapacitating myalgia and eosinophilia in blood, fluids and secretions. Most patients report previous L-tryptophan intake. Respiratory manifestations are found in up to 80% of the cases, occasionally as the only manifestation. Treatment includes drug discontinuation and administration of corticosteroids. Here, we describe the case of a 61-year-old female admitted with acute respiratory failure after using L-tryptophan, hydroxytryptophan and other drugs. The patient presented eosinophilia, together with elevated eosinophil counts in the bronchoalveolar lavage and pleural effusion. After discontinuation of the drugs previously used, corticosteroids were administered, resulting in clinical and radiological improvement within just a few days.

Keywords: Respiratory insufficiency; Tryptophan; Eosinophilia-myalgia syndrome.

Objective: Bedside lung ultrasound (LUS) is a noninvasive, readily available imaging modality that can complement clinical evaluation. The Bedside Lung Ultrasound in Emergency (BLUE) protocol has demonstrated a high diagnostic accuracy in patients with acute respiratory failure (ARF). Recently, bedside LUS has been added to the medical training program of our ICU. The aim of this study was to investigate the accuracy of LUS based on the BLUE protocol, when performed by physicians who are not ultrasound experts, to guide the diagnosis of ARF. Methods: Over a one-year period, all spontaneously breathing adult patients consecutively admitted to the ICU for ARF were prospectively included. After training, 4 non-ultrasound experts performed LUS within 20 minutes of patient admission. They were blinded to patient medical history. LUS diagnosis was compared with the final clinical diagnosis made by the ICU team before patients were discharged from the ICU (gold standard). Results: Thirty-seven patients were included in the analysis (mean age, 73.2  14.7 years; APACHE II, 19.2  7.3). LUS diagnosis had a good agreement with the final diagnosis in 84% of patients (overall kappa, 0.81). The most common etiologies for ARF were pneumonia (n = 17) and hemodynamic lung edema (n = 15). The sensitivity and specificity of LUS as measured against the final diagnosis were, respectively, 88% and 90% for pneumonia and 86% and 87% for hemodynamic lung edema. Conclusions: LUS based on the BLUE protocol was reproducible by physicians who are not ultrasound experts and accurate for the diagnosis of pneumonia and hemodynamic lung edema.

Keywords: Ultrasonography, interventional; Respiratory insufficiency; Intensive care units.

Neuromuscular diseases affect alveolar air exchange and therefore cause chronic respiratory failure. The onset of respiratory failure can be acute, as in traumas, or progressive (slow or rapid), as in amyotrophic lateral sclerosis, muscular dystrophies, diseases of the myoneural junction, etc. Respiratory muscle impairment also affects cough efficiency and, according to the current knowledge regarding the type of treatment available in Brazil to these patients, it can be said that the high rates of morbidity and mortality in these individuals are more often related to the fact that they cough inefficiently rather than to the fact that they ventilate poorly. In this review, with the objective of presenting the options of devices available to support and substitute for natural ventilation in patients with neuromuscular diseases, we have compiled a brief history of the evolution of orthopedic braces and prostheses used to aid respiration since the end of the 19th century. In addition, we highlight the elements that are fundamental to the diagnosis of alveolar hypoventilation and of failure of the protective cough mechanism: taking of a clinical history; determination of peak cough flow; measurement of maximal inspiratory and expiratory pressures; spirometry in two positions (sitting and supine); pulse oximetry; capnography; and polysomnography. Furthermore, the threshold values available in the literature for the use of nocturnal ventilatory support and for the extension of this support through the daytime period are presented. Moreover, the maneuvers used to increase cough efficiency, as well as the proper timing of their introduction, are discussed.

Keywords: Respiratory insufficiency/diagnosis; Chronic disease; Respiratory insufficiency/therapy;

Herein, we report an instance of occupational exposure to food preservatives and resultant acute respiratory failure in three workers. The toxicological analysis revealed that mixing the particular food preservatives involved, a procedure that was performed by the three workers involved, produced NO2, the inhalation of which caused the pulmonary edema and respiratory failure. With time, the pulmonary damage was completely reversed in all three individuals. Accompanying this case report is a brief review of the literature regarding acute pulmonary injury resulting from occupational exposure to chemicals. We emphasize the importance of training, as well as of the use of protective gear, for workers who handle chemical substances.

Keywords: Respiratory insufficiency; Occupational exposure; Occupational diseases; Case report

Objective: To determine the impact that open lung biopsy findings have on decisions regarding changes in the treatment strategies employed for critically ill patients presenting diffuse pulmonary infiltrates and suffering from refractory acute respiratory failure, as well as on their clinical improvement. Methods: This study involved 12 mechanically ventilated patients with acute respiratory failure who were subjected to open lung biopsy (by thoracotomy) after not presenting a clinical response to standard treatment. Results: The single most common cause of the acute respiratory failure was viral infection, which was identified in 5 patients (40%). The pre-operative evaluation of the cause of respiratory failure was modified in 11 patients (91.6%), and a specific diagnosis was made in 100% of the cases. Regardless of changes in treatment regimen, the mortality rate was 50%. Six patients (50%) survived to be discharged from the hospital. All of the discharged patients survived for at least one year after the open lung biopsy, for an overall one-year survival rate of 50% among the 12 patients studied. For the patients who died in the hospital, the time of survival after open lung biopsy was 14 + 10.8 days. Conclusion: We conclude that open lung biopsy is a useful tool in the management of acute respiratory failure when there is no clinical improvement after standard treatment, since it can lead to a specific diagnosis that requires distinct treatment, which probably lowers the mortality rate among such patients.

Keywords: Respiratory distress syndrome, adult; Lung/pathology; Biposy; Acute respiratory syndrome

The synchronous presentation of pulmonary and hepatic nodules in a patient with previously resected bronchogenic carcinoma raises suspicion of recurrence and mandates restaging. We present the case of a 71-year-old male with a history of lobectomy with pericardial resection and mediastinal lymphadenectomy (T3N0M0). At five years after the operation, he presented with a new pulmonary lesion. Restaging detected a synchronous nodule in the liver. Despite the strong suspicion of tumor recurrence, further investigation with a percutaneous liver biopsy revealed hepatocellular carcinoma. In order to investigate the etiology of the pulmonary lesion (hypotheses of recurrent bronchial cancer and of metastatic hepatocellular carcinoma), an open lung biopsy was performed, which revealed chronic inflammatory tissue with foci of anthracosis and dystrophic calcification. The patient was submitted to a non-anatomic resection of the liver lesion. The postoperative course was uneventful, and the patient was discharged on postoperative day 10. This report highlights the relevance of the histopathological diagnosis in patients with a history of bronchogenic carcinoma and suspicion of tumor recurrence. Differential diagnoses and the treatment administered are discussed.

Keywords: Carcinoma, bronchogenic; Neoplasm metastasis; Carcinoma, hepatocellular.

Introduction: Spirometry and analysis of blood gases data have been extensively used to assess ventilatory limitation and prognosis of COPD patients. However, functional physical tests, such as the six-minute walk test (6wt) have been used for the dynamic assessment of COPD patients. Objective: To determine correlations between respiratory function test data and the six-minute walk test in COPD patients. Patients and methods: 45 patients were submitted to clinical history survey and complete physical examination performed by the medical staff of the Pneumology Department of the Brasilia University Hospital, followed by spirometry, analysis of arterial blood gases, maximal respiratory pressures data, and the six-minute walk test. Results: Concerning the spirometric, analysis of blood gases and maximal respiratory pressures data, statistically significant positive correlations (p < 0.05) between FEV1, PaO2, SpO2, MEP and the six-minute walk test were obtained. Conclusions: For the studied group, the six minute walk test has significant correlation with FEV1, PaO2, SpO2 and MEP, and can be used as an alternative functional assessment of COPD patients.