Effect of Ventilator Settings on Mechanical Power During Simulated Mechanical Ventilation of Patients With ARDS.

BACKGROUND: In recent years, mechanical power (MP) has emerged as an important concept that can significantly impact outcomes from mechanical ventilation. Several individual components of ventilatory support such as tidal volume (VT), breathing frequency, and PEEP have been shown to contribute to the extent of MP delivered from a mechanical ventilator to patients in respiratory distress/failure. The aim of this study was to identify which common individual setting of mechanical ventilation is more efficient in maintaining safe and protective levels of MP using different modes of ventilation in simulated subjects with ARDS. METHODS: We used an interactive mathematical model of ventilator output during volume control ventilation (VCV) with either constant inspiratory flow (VCV-CF) or descending ramp inspiratory flow, as well as pressure control ventilation (PCV). MP values were determined for simulated subjects with mild, moderate, and severe ARDS; and whenever MP > 17 J/min, VT, breathing frequency, or PEEP was manipulated independently to bring back MP to ≤ 17 J/min. Finally, the optimum VT-breathing frequency combinations for MP = 17 J/min were determined with all 3 modes of ventilation. RESULTS: VCV-CF always resulted in the lowest MPs while PCV resulted in highest MPs. Reductions in VT were the most efficient for maintaining safer and protective MP. At targeted MPs of 17 J/min and maximized minute ventilation, the optimum VT-breathing frequency combinations were 250-350 mL for VT and 32-35 breaths/min for breathing frequency in mild ARDS, 200-350 mL for VT and 34-40 breaths/min for breathing frequency in moderate ARDS, and 200-300 mL for VT and 37-45 breaths/min for breathing frequency for severe ARDS. CONCLUSIONS: VCV-CF resulted in the lowest MP. VT was the most efficient for maintaining safe and protective MP in a mathematical simulation of subjects with ARDS. In the context of maintaining low and safe MPs, ventilatory strategies with lower-than-normal VT and higher-than-normal breathing frequency will need to be implemented in patients with ARDS.

Ratio of oxygen saturation index for predicting high-flow nasal cannula outcomes in emergency department for COVID-19 patients with severe hypoxemia: A retrospective study.

OBJECTIVES: High-flow nasal cannula (HFNC) oxygen therapy has been used as an initial ventilatory support for coronavirus disease 2019 (COVID-19) patients with mixed levels of acute hypoxemic respiratory failure (AHRF). However, the effectiveness of HFNC when used as initial ventilatory support in COVID-19 patients with severe AHRF exclusively is not well documented. Ratio of oxygen saturation (ROX) index (ROX = [SpO2/fraction of inspired oxygen]/respiratory rate) was shown to predict the outcome of HFNC in intensive care unit patients. Our study aimed to evaluate the utility of the ROX index for predicting HFNC therapy success/failure in COVID-19 patients with severe AHRF when HFNC is used as the first line of ventilatory support. METHODS: Retrospective study in 67 COVID-19 patients with severe AHRF receiving HFNC in the emergency department at a tertiary care academic medical center. ROX index was determined at 0, 2, 6, 12, and 24 h of HFNC onset. The need to escalate to noninvasive or invasive ventilatory support was documented. The receiver operating characteristic curves were performed and areas under the curves (AUCs) were calculated to evaluate the accuracy of ROX index for differentiating between patients who will succeed or fail HFNC therapy. RESULTS: HFNC therapy was successful in 19 patients (28.1%) and failed in 48 patients (71.6%). ROX index after 6 h of HFNC initiation had the best predictive capacity for the outcome of HFNC therapy (AUC = 0.78). ROX index >4.4 at 6 h of HFNC onset was significantly associated with HFNC success/failure. CONCLUSION: ROX index at 6 h after initiating HFNC therapy in COVID-19 patients with severe AHRF has a good predictive capacity for HFNC success/failure.

Intraoperative mechanical power and postoperative pulmonary complications in low-risk surgical patients: a prospective observational cohort study.

BACKGROUND: Inadequate intraoperative mechanical ventilation (MV) can lead to ventilator-induced lung injury and increased risk for postoperative pulmonary complications (PPCs). Mechanical power (MP) was shown to be a valuable indicator for MV outcomes in critical care patients. The aim of this study is to assess the association between intraoperative MP in low-risk surgical patients undergoing general anesthesia and PPCs. METHODS: Two-hundred eighteen low-risk surgical patients undergoing general anesthesia for elective surgery were included in the study. Intraoperative mechanical ventilatory support parameters were collected for all patients. Postoperatively, patients were followed throughout their hospital stay and up to seven days post discharge for the occurrence of any PPCs. RESULTS: Out of 218 patients, 35% exhibited PPCs. The average body mass index, tidal volume per ideal body weight, peak inspiratory pressure, and MP were significantly higher in the patients with PPCs than in the patients without PPCs (30.3 ± 8.1 kg/m2 vs. 26.8 ± 4.9 kg.m2, p < 0.001; 9.1 ± 1.9 ml/kg vs. 8.6 ± 1.4 ml/kg, p = 0.02; 20 ± 4.9 cmH2O vs. 18 ± 3.7 cmH2O, p = 0.001; 12.9 ± 4.5 J/min vs. 11.1 ± 3.7 J/min, p = 0.002). A multivariable regression analysis revealed MP as the sole significant predictor for the risk of postoperative pulmonary complications [OR 1.1 (95% CI 1.0-1.2, p = 0.036]. CONCLUSIONS: High intraoperative mechanical power is a risk factor for developing postoperative pulmonary complications. Furthermore, intraoperative mechanical power is superior to other traditional mechanical ventilation variables in identifying surgical patients who are at risk for developing postoperative pulmonary complications. CLINICAL TRIAL REGISTRATION: NCT03551899; 24/02/2017.

Non-invasive Ventilation and High-Flow Nasal Cannula in Head/Brain Injury with Risk of Pneumocephalus: Is There a Potential Application?

Non-invasive ventilation application in neurocritical care with risk of pneumocephalus is controversial. Non-invasive ventilation-related increased intrathoracic pressure increases intracranial pressure via direct transmission of intrathoracic pressure to the intracranial cavity. In addition, increased thoracic pressure decreases venous return to the heart and increases vena jugularis interna pressure, thereby increasing cerebral blood volume. Pneumocephalus is one of the major concerns after non-invasive ventilation application in head/brain trauma patients. Non-invasive mechanical ventilation may be performed in limited conditions in head trauma/brain surgery with appropriate and close monitoring. High-flow nasal cannula oxygen therapy can provide higher FiO2 as manifested by a larger increase in PaO2/FiO2 ratio and provide the theoretical basis in pneumocephalus because augmenting the PaO2 more effectively would accelerate nitrogen (N2) washout. As a result, non-invasive mechanical ventilation may be performed in limited manner in head trauma/ brain surgery with appropriate and close monitoring.

Role of Sedation and Analgesia during Noninvasive Ventilation: Systematic Review of Recent Evidence and Recommendations.

Aim: This systematic review aimed to investigate the drugs used and their potential effect on noninvasive ventilation (NIV). Background: NIV is used increasingly in acute respiratory failure (ARF). Sedation and analgesia are potentially beneficial in NIV, but they can have a deleterious impact. Proper guidelines to specifically address this issue and the recommendations for or against it are scarce in the literature. In the most recent guidelines published in 2017 by the European Respiratory Society/American Thoracic Society (ERS/ATS) relating to NIV use in patients having ARF, the well-defined recommendation on the selective use of sedation and analgesia is missing. Nevertheless, some national guidelines suggested using sedation for agitation. Methods: Electronic databases (PubMed/Medline, Google Scholar, and Cochrane library) from January 1999 to December 2019 were searched systematically for research articles related to sedation and analgosedation in NIV. A brief review of the existing literature related to sedation and analgesia was also done. Review results: Sixteen articles (five randomized trials) were analyzed. Other trials, guidelines, and reviews published over the last two decades were also discussed. The present review analysis suggests dexmedetomidine as the emerging sedative agent of choice based on the most recent trials because of better efficacy with an improved and predictable cardiorespiratory profile. Conclusion: Current evidence suggests that sedation has a potentially beneficial role in patients at risk of NIV failure due to interface intolerance, anxiety, and pain. However, more randomized controlled trials are needed to comment on this issue and formulate strong evidence-based recommendations. How to cite this article: Karim HMR, Sarc I, Calandra C, Spadaro S, Mina B, Ciobanu LD, et al. Role of Sedation and Analgesia during Noninvasive Ventilation: Systematic Review of Recent Evidence and Recommendations. Indian J Crit Care Med 2022;26(8):938-948.

Validation of the Arabic Severe Respiratory Insufficiency Questionnaire.

BACKGROUND/OBJECTIVES: Assessment of Health-Related Quality of Life (HRQL) in patients with chronic respiratory insufficiency requiring Home Mechanical Ventilation (HMV) requires a valid measurement tool. The Severe Respiratory Insufficiency (SRI) questionnaire, originally developed in German, has been translated into different languages and tested in different contexts, but has so far not been in use in Arabic-speaking populations. The objective of this study is to validate the Arabic version of the SRI questionnaire in a sample of Arabic-speaking patients from Lebanon. METHODS: Following forward/backward translations, the finalized Arabic version was administered to 149 patients (53 males-96 females, age 69.80 ± 10 years) receiving HMV. Patients were recruited from outpatient clinics and visited at home. The Arabic SRI and the 36-Item Short-Form Health Survey (SF-36) were administered, in addition to questions on sociodemographics and medical history. Exploratory Factor Analysis (EFA) was used to explore dimensionality; internal consistency reliability of the unidimensional scale and its subscales was assessed using Cronbach's alpha. External nomological validity was examined by assessing the correlation between the SRI and SF-36 scores. RESULTS: The 49-item Arabic SRI scale showed a high internal consistency reliability (Cronbach alpha for the total scale was 0.897 and ranged between 0.73 and 0.87 for all subscales). Correlations between the SF-36-Mental Health Component MHC and SF-36-Physical Health Component with SRI-Summary Scale were 0.57 and 0.66, respectively, with higher correlations observed between the SF-36 and specific sub-scales such as the Physical Functioning and the Social Functioning subscales [r = 0.81 and r = 0.74 (P < 0.01), respectively]. CONCLUSION AND RECOMMENDATIONS: The Arabic SRI is a reliable and valid tool for assessing HRQL in patients with chronic respiratory insufficiency receiving home mechanical ventilation.

Secretion management in patients with ineffective airway clearance with non-invasive mechanical ventilation use: Expert guidance for clinical practice.

Non-invasive ventilation (NIV) is a mainstay of management of chronic respiratory failure in many disorders which are known to cause abnormal airway secretion clearance. Currently, there is no guidance regarding either the secretion handling during NIV use or the role of NIV in secretion management in these patients. The aim of this document was to provide an overview of the various techniques available in the management of respiratory secretions and their use in conjunction with NIV. Literature search was performed using the keywords, "(secretion OR secretions) AND (noninvasive ventilation OR NIV)" on PubMed and EMBASE. The search yielded 1681 and 509 titles from PubMed and EMBASE, respectively. After screening, 19 articles were included in this review. Suggestions of the expert panel were formulated by mutual consensus after reviewing the relevant literature. The draft of the expert panel's suggestions was circulated among all authors via electronic mail for comments. Any conflicts were resolved by mutual discussion to achieve agreement. The final document was approved by all. This document by the International Network for Airway Secretions Management in NIV describes various airway secretion clearance techniques. It provides the expert panel's suggestions for the use of these techniques in conjunction with NIV for patients with muco-obstructive and neuromuscular disorders.

High-Flow Nasal Oxygen Therapy in Acute Hypoxemic Respiratory Failure: Concise Review on Technology and Initial Methodology.

High-flow nasal cannula oxygen therapy (HFNCOT) system consists of an air/oxygen supply system capable of delivering up to 100% humidified and heated oxygen at a flow rate of up to 80 L/min. The system includes a blender, active humidifier, single heated tube, and nasal cannula. HFNCOT has many physiological advantages compared with other standard oxygen therapies, such as anatomical dead space washout, more constant fraction of inspired oxygen, positive end-expiratory (PEEP) effect, supplement of adequate humidification and maintenance of muco-ciliary function. HFNCOT is mostly used for hypoxemic acute respiratory failure, although it also has other indications. HFNCOT is a common choice of physicians as its technology makes it more silent and comfortable. Though HFNCOT is used in many clinical settings, there is a lack of publications addressing devices and initial settings. We present a review on HFNCOT, with focus on device and application methodology.

The role of non-invasive ventilation in weaning and decannulating critically ill patients with tracheostomy: A narrative review of the literature.

INTRODUCTION: Invasive mechanical ventilation (IMV) is associated with several complications. Placement of a long-term airway (tracheostomy) is also associated with short and long-term risks for patients. Nevertheless, tracheostomies are placed to help reduce the duration of IMV, facilitate weaning and eventually undergo successful decannulation. METHODS: We performed a narrative review by searching PubMed, Embase and Medline databases to identify relevant citations using the search terms (with synonyms and closely related words) "non-invasive ventilation", "tracheostomy" and "weaning". We identified 13 publications comprising retrospective or prospective studies in which non-invasive ventilation (NIV) was one of the strategies used during weaning from IMV and/or tracheostomy decannulation. RESULTS: In some studies, patients with tracheostomies represented a subgroup of patients on IMV. Most of the studies involved patients with underlying cardiopulmonary comorbidities and conditions, and primarily involved specialized weaning centres. Not all studies provided data on decannulation, although those which did, report high success rates for weaning and decannulation when using NIV as an adjunct to weaning patient off ventilatory support. However, a significant percentage of patients still needed home NIV after discharge. CONCLUSIONS: The review supports a potential role for NIV in weaning patients with a tracheostomy either off the ventilator and/or with its decannulation. Additional research is needed to develop weaning protocols and better characterize the role of NIV during weaning.

Comparison of the Oxygenation Factor and the Oxygenation Ratio in Subjects With ARDS.

BACKGROUND: The oxygenation ratio (ie, [Formula: see text]/[Formula: see text]) remains the most commonly used index for assessing oxygenation and disease severity in patients with acute ARDS. However, the oxygenation ratio does not account for mechanical ventilation settings. We hypothesized that the oxygenation factor (ie, oxygenation ratio/mean airway pressure) is superior to the oxygenation ratio in reflecting oxygenation in patients with ARDS and results in a different classification of ARDS severity. METHODS: In 150 subjects with ARDS (50 severe, 50 moderate, and 50 mild), arterial blood gas, mean airway pressure, static lung compliance, driving pressure, and mechanical power were obtained. The oxygenation ratio and the oxygenation factor were then calculated. Receiver operating characteristic curves were constructed for oxygenation ratio and oxygenation factor at lung compliance > 40 mL/cm H2O, driving pressure < 15 cm H2O, and mechanical power < 17 J/min, thresholds that are known to predict survival in patients with ARDS. Subjects were reclassified for ARDS severity on the basis of the oxygenation factor and compared to classification on the basis of the oxygenation ratio. RESULTS: Areas under the receiver operating characteristic curves for the oxygenation factor were significantly higher than for the oxygenation ratio. Reclassification of ARDS severity using the oxygenation factor did not affect subjects classified as having severe ARDS per the oxygenation ratio. However, 52% of subjects with moderate ARDS per the oxygenation ratio criteria were reclassified as either severe (25 subjects) or mild ARDS (1 subject) on the basis of oxygenation factor criteria. Also, 54% of subjects with mild ARDS per the oxygenation ratio criteria were reclassified as severe (4 subjects), moderate (21 subjects), or non-ARDS (2 subjects) on the basis of oxygenation factor criteria. CONCLUSIONS: The oxygenation factor was a superior ARDS oxygenation index compared to the oxygenation ratio and should be considered as a substitute criteria for classification of the severity of ARDS. (ClinicalTrials.gov registration NCT03946189.).

Non-invasive ventilation in patients with an altered level of consciousness. A clinical review and practical insights.

Non-invasive ventilation has gained an increasingly pivotal role in the treatment of acute hypoxemic and/or hypercapnic respira-tory failure and offers multiple advantages over invasive mechanical ventilation. Some of these advantages include the preserva-tion of airway defense mechanisms, a reduced need for sedation, and an avoidance of complications related to endotracheal intubation. Despite its advantages, non-invasive ventilation has some contraindications that include, among them, severe encephalopathy. In this review article, the rationale, evidence, and drawbacks of the use of noninvasive ventilation in the context of hypercapnic and non-hypercapnic patients with an altered level of consciousness are analyzed.

Continuous Positive Airway Pressure (CPAP) in Non-Apneic Asthma: A Clinical Review of Current Evidence.

The use of continuous positive airway pressure (CPAP) in asthma has been a point of debate over the past several years. Various studies, including those on animals and humans have attempted to understand the role and pathophysiology of CPAP in patients with either well controlled or poorly controlled asthma. The aim of this manuscript is to review the currently available literature on the physiologic and clinical effects of CPAP in animal models of asthma and on humans with stable asthma.

Noninvasive ventilation: education and training. A narrative analysis and an international consensus document.

Noninvasive ventilation (NIV) is an increasingly used method of respiratory support. The use of NIV is expanding over the time and if properly applied, it can save patients' lives and improve long-term prognosis. However, both knowledge and skills of its proper use as life support are paramount. This systematic review aimed to assess the importance of NIV education and training. Literature search was conducted (MEDLINE: 1990 to June, 2018) to identify randomized controlled studies and systematic reviews with the results analyzed by a team of experts across the world through e-mail based communications. Clinical trials examining the impact of education and training in NIV as the primary objective was not found. A few studies with indirect evidence, a simulation-based training study, and narrative reviews were identified. Currently organized training in NIV is implemented only in a few developed countries. Due to a lack of high-grade experimental evidence, an international consensus on NIV education and training based on opinions from 64 experts across the twenty-one different countries of the world was formulated. Education and training have the potential to increase knowledge and skills of the clinical staff who deliver medical care using NIV. There is a genuine need to develop structured, organized NIV education and training programs, especially for the developing countries.

Nondepolarizing muscle relaxant improves direct laryngoscopy view with no effect on face mask ventilation / Relaxantes musculares não despolarizantes melhoram a visibilidade em laringoscopia direta sem efeito sobre a ventilação via máscara facial

Abstract Background: Difficult or impossible face mask ventilation complicated with difficult tracheal intubation during anesthesia induction occurs in 0.4% of adult anesthesia cases, possibly leading to life-threatening complications. Because of such catastrophes, muscle relaxants have been recommended to be administered after confirming adequate face mask ventilation without a solid scientific validation of this principal. Methods: In this observational study, the ease of ventilation and the scores of direct laryngoscopy views before and after administration of cisatracurium were assessed in ninety young healthy adults, without anesthetic risks and without foreseen difficult intubation and who were scheduled for general elective surgeries. Results: Before muscle relaxation, 43 patients (48%) were Cormack Grade I, while the remaining 47 patients (52%) were either Cormack Grade II (28 patients, 31%) or Cormack Grade II (19 patients, 21%). Following muscle relaxation with cisatracurium, the number of patients with Cormack Grade I significantly increased from 43 patients (48%) to 65 patients (72%) (p = 0.0013). Only 1 patient out of 19 patients (5%) improved his Cormack grade from Grade III to Grade I while 16 out 19 patients (84%) improved their Cormack grade from Grade III to Grade II after the use of cisatracurium. The quality of face mask ventilation did not differ with and without muscle relaxants in all patients. Conclusion: The use of cisatracurium in healthy young adults undergoing general elective surgeries with no anticipated difficult endotracheal intubation had no effect on the quality of face mask ventilation despite resulting in a quantifiable improvement in the laryngeal view.

Resumo Justificativa: A ventilação difícil ou impossível via máscara facial complicada pela intubação traqueal difícil durante a indução da anestesia ocorre em 0,4% dos casos de anestesia em adultos, possivelmente leva a complicações fatais. Devido a tais catástrofes, recomendou-se que a administração de relaxantes musculares seja feita após a confirmação de ventilação adequada via máscara facial, sem uma validação científica sólida dessa conduta. Métodos: Neste estudo observacional, a facilidade de ventilação e os escores de visibilidade em laringoscopia direta antes e após a administração de cisatracúrio foram avaliados em 90 adultos jovens e saudáveis, sem riscos anestésicos e sem intubação difícil prevista, agendados para cirurgias eletivas gerais. Resultados: Antes do relaxamento muscular, 43 pacientes (48%) eram Cormack Grau I, enquanto os 47 (52%) restantes eram ou Cormack Grau II (28, 31%) ou Cormack Grade III (19, 21%). Após o relaxamento muscular com cisatracúrio, o número de pacientes com Cormack Grau I aumentou significativamente de 43 (48%) para 65 (72%) (p = 0,0013). Apenas um paciente (5%) dos 19 melhorou sua classificação de Cormack do Grau III para o Grau I, enquanto 16 dos 19 (84%) melhoraram suas classificações de Cormack do Grau III para o grau II após o uso de cisatracúrio. A qualidade da ventilação via máscara facial não diferiu com ou sem relaxantes musculares em todos os pacientes. Conclusão: O uso de cisatracúrio em adultos jovens saudáveis submetidos a cirurgias eletivas gerais sem intubação traqueal difícil prevista não teve efeito sobre a qualidade da ventilação via máscara facial, mesmo resultando em melhora quantificável da visibilidade da laringe.

[Nondepolarizing muscle relaxant improves direct laryngoscopy view with no effect on face mask ventilation]. / Relaxantes musculares não despolarizantes melhoram a visibilidade em laringoscopia direta sem efeito sobre a ventilação via máscara facial.

BACKGROUND: Difficult or impossible face mask ventilation complicated with difficult tracheal intubation during anesthesia induction occurs in 0.4% of adult anesthesia cases, possibly leading to life-threatening complications. Because of such catastrophes, muscle relaxants have been recommended to be administered after confirming adequate face mask ventilation without a solid scientific validation of this principal. METHODS: In this observational study, the ease of ventilation and the scores of direct laryngoscopy views before and after administration of cisatracurium were assessed in ninety young healthy adults, without anesthetic risks and without foreseen difficult intubation and who were scheduled for general elective surgeries. RESULTS: Before muscle relaxation, 43 patients (48%) were Cormack Grade I, while the remaining 47 patients (52%) were either Cormack Grade II (28 patients, 31%) or Cormack Grade II (19 patients, 21%). Following muscle relaxation with cisatracurium, the number of patients with Cormack Grade I significantly increased from 43 patients (48%) to 65 patients (72%) (p=0.0013). Only 1 patient out of 19 patients (5%) improved his Cormack grade from Grade III to Grade I while 16 out 19 patients (84%) improved their Cormack grade from Grade III to Grade II after the use of cisatracurium. The quality of face mask ventilation did not differ with and without muscle relaxants in all patients. CONCLUSION: The use of cisatracurium in healthy young adults undergoing general elective surgeries with no anticipated difficult endotracheal intubation had no effect on the quality of face mask ventilation despite resulting in a quantifiable improvement in the laryngeal view.

Prediction of inspired oxygen fraction for targeted arterial oxygen tension following open heart surgery in non-smoking and smoking patients.

Simple and accurate expressions describing the PaO2-FiO2 relationship in mechanically ventilated patients are lacking. The current study aims to validate a novel mathematical expression for accurate prediction of the fraction of inspired oxygen that will result in a targeted arterial oxygen tension in non-smoking and smoking patients receiving mechanical ventilation following open heart surgeries. One hundred PaO2-FiO2 data pairs were obtained from 25 non-smoking patients mechanically ventilated following open heart surgeries. One data pair was collected at each of FiO2 of 40, 60, 80, and 100% while maintaining same mechanical ventilation support settings. Similarly, another 100 hundred PaO2-FiO2 data pairs were obtained from 25 smoking patients mechanically ventilated following open heart surgeries. The utility of the new mathematical expression in accurately describing the PaO2-FiO2 relationship in these patients was assessed by the regression and Bland-Altman analyses. Significant correlations were seen between the true and estimated FiO2 values in non-smoking (r2 = 0.9424; p < 0.05) and smoking (r2 = 0.9466; p < 0.05) patients. Tight biases between the true and estimated FiO2 values for non-smoking (3.1%) and smoking (4.1%) patients were observed. Also, significant correlations were seen between the true and estimated PaO2/FiO2 ratios in non-smoking (r2 = 0.9530; p < 0.05) and smoking (r2 = 0.9675; p < 0.05) patients. Tight biases between the true and estimated PaO2/FiO2 ratios for non-smoking (-18 mmHg) and smoking (-16 mmHg) patients were also observed. The new mathematical expression for the description of the PaO2-FiO2 relationship is valid and accurate in non-smoking and smoking patients who are receiving mechanical ventilation for post cardiac surgery.

PATIENT-VENTILATION ASYNCHRONY CAUSING NEGATIVE PRESSURE PULMONARY EDEMA IN AN INTUBATED OBESE PATIENT.

Negative pressure pulmonary edema is a potentially life-threatening condition that may occur when a large negative intrathoracic pressure is generated against a 'physically' obstructed upper airway during emergence from anesthesia. We report a 35 year old male patient who is morbidly obese and undergoing laparoscopic gastric bypass who developed negative pressure pulmonary edema without any evidence of a 'physical' upper airway obstruction. In our patient, the negative pressure pulmonary edema occurred after complete reversal of neuromuscular blockade and during manual positive pressure ventilation with the endotracheal tube still in place and in the presence of an oral airway. Since the patient was still intubated and had an airway in place with no possibility for physical obstruction, we speculate that the occurrence of the negative pressure pulmonary edema was mainly due to a 'functional' obstruction secondary to the severe patient-ventilation asynchrony that ensued upon reversal of the neuromuscular blockade.