Efficacy and safety of noninvasive positive pressure ventilation in the treatment of acute respiratory failure after cardiac surgery

Background Although noninvasive positive pressure ventilation （NPPV） has been successfully used for various kinds of acute respiratory failure,the data are limited regarding its application in postoperative respiratory failure after cardiac surgery.Therefore,we conducted a prospective randomized control study in a university surgical intensive care unit to evaluate the efficacy and safety of NPPV in the treatment of acute respiratory failure after cardiac surgery,and explore the predicting factors of NPPV failure.Methods From September 2011 to November 2012 patients with acute respiratory failure after cardiac surgery who had indication for the use of NPPV were randomly divided into a NPPV treatment group （NPPV group） and the conventional treatment group （control group）.The between-group differences in the patients＇ baseline characteristics,re-intubation rate,tracheotomy rate,ventilator associated pneumonia （VAP） incidence,in-hospital mortality,mechanical ventilation time after enrollment （MV time）,intensive care unit （ICU） and postoperative hospital stays were compared.The factors that predict NPPV failure were analyzed.Results During the study period,a total of 139 patients who had acute respiratory failure after cardiac surgery were recorded,and 95 of them met the inclusion criteria,which included 59 males and 36 females with a mean age of （61.5±11.2） years.Forty-three patients underwent coronary artery bypass grafting （CABG）,23 underwent valve surgery,13 underwent CABG＋valve surgery,13 underwent major vascular surgery,and three underwent other surgeries.The NPPV group had 48 patients and the control group had 47 patients.In the NPPV group,the re-intubation rate was 18.8％,tracheotomy rate was 12.5％,VAP incidence was 0,and the in-hospital mortality was 18.8％,significantly lower than in the control group 80.9％,29.8％,17.0％ and 38.3％ respectively,P ＜0.05 or P ＜0.01.The MV time and ICU stay （expressed as the median （P25,P75）） were 18.0 （9.2,35.0） hours and 4.0 （2.0,5.0） days,which were significantly shorter than in the control group,96.0 （26.0,240.0） hours and 6.0 （4.0,9.0） days respectively,P ＜0.05 or P ＜0.01.The postoperative hospital stays of the two groups were similar.The univariate analysis showed that the NPPV success subgroup had more patients with acute lung injury （ALl） （17 vs.0,P=0.038）,fewer patients with pneumonia （2 vs.7,P ＜0.001） and lower acute physiology and chronic health evaluation Ⅱ （APACHE Ⅱ） scores （16.1±2.8 vs.21.8±3.2,P ＜0.001）.Multivariate analysis showed that pneumonia （P=-0.027） and a high APACHE Ⅱ score ＞20 （P=-0.002） were the independent risk factors of NPPV failure.Conclusions We conclude that NPPV can be applied in selected patients with acute respiratory failure after cardiac surgery to reduce the need of re-intubation and improve clinical outcome as compared with conventional treatment.Pneumonia and a high APACHE Ⅱ score ＞20 might be the independent risk factors of NPPV failure in this group of patients.

Application of Venovenous Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Failure： Situations, Issues, and Trends

Extracorporeal membrane oxygenation （ECMO） is a type of extracorporeal life support （ECLS）, and technological advances have expanded the use of this technique from the confines of the operating room by producing a compact system that could revolutionize the treatment of different types of respiratory failure.

Oxygenation strategy during acute respiratory failure in immunocompromised patients

Acute respiratory failure(ARF)in immunocompromised patients remains challenging to treat.A large number of case require admission to intensive care unit(ICU)where mortality remains high.Oxygenation without intubation is important in this setting.This review summarizes recent studies assessing oxygenation devices for immunocompromised patients.Previous studies showed that non-invasive ventilation(NIV)has been associated with lower intubation and mortality rates.Indeed,in recent years,the outcomes of immunocompromised patients admitted to the ICU have improved.In the most recent randomized controlled trials,including immunocompromised patients admitted to the ICU with ARF,neither NIV nor high-flow nasal oxygen(HFNO)could reduce the mortality rate.In this setting,other strategies need to be tested to decrease the mortality rate.Early admission strategy and avoiding late failure of oxygenation strategy have been assessed in retrospective studies.However,objective criteria are still lacking to clearly discriminate time to admission or time to intubation.Also,diagnosis strategy may have an impact on intubation or mortality rates.On the other hand,lack of diagnosis has been associated with a higher mortality rate.In conclusion,improving outcomes in immunocompromised patients with ARF may include strategies other than the oxygenation strategy alone.This review discusses other unresolved questions to decrease mortality after ICU admission in such patients.

Efficacy and safety of awake prone positioning in the treatment of non-intubated spontaneously breathing patients with COVID-19-related acute respiratory failure:A systematic review and meta-analysis

Background Since the beginning of the coronavirus disease 2019(COVID-19)pandemic,prone positioning has been widely applied for non-intubated,spontaneously breathing patients.However,the efficacy and safety of prone positioning in non-intubated patients with COVID-19-related acute hypoxemic respiratory failure remain unclear.We aimed to systematically analyze the outcomes associated with awake prone positioning(APP).Methods We conducted a systematic literature search of PubMed/MEDLINE,Cochrane Library,Embase,and Web of Science from January 1,2020,to June 3,2022.This study included adult patients with acute respiratory failure caused by COVID-19.The Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines were followed,and the study quality was assessed using the Cochrane risk-of-bias tool.The primary outcome was the reported cumulative intubation risk across randomized controlled trials(RCTs),and the effect estimates were calculated as risk ratios(RRs;95%confidence interval[CI]).Results A total of 495 studies were identified,of which 10 fulfilled the selection criteria,and 2294 patients were included.In comparison to supine positioning,APP significantly reduced the need for intubation in the overall population(RR=0.84,95%CI:0.74–0.95).The two groups showed no significant differences in the incidence of adverse events(RR=1.16,95%CI:0.48–2.76).The meta-analysis revealed no difference in mortality between the groups(RR=0.93,95%CI:0.77–1.11).Conclusions APP was safe and reduced the need for intubation in patients with respiratory failure associated with COVID-19.However,it did not significantly reduce mortality in comparison to usual care without prone positioning.

Uniphyline-Induced Hypophosphatemia: A Rare Etiology of Severe Respiratory Failure

Hypophosphataemia is defined as low level of phosphate in the blood (normal range 0.8 - 1.4 mmol/l), which can be drug-induced such as uniphyline. We present a case of elderly female patient with known chronic obstructive pulmonary disease, admitted with acute respiratory failure and low serum phosphate level, her clinical signs and serum phosphate level did not improve with conventional therapy and intravenous phosphate replacement, until her recently commenced uniphyline was discontinued. This highlights the importance of awareness amongst the clinicians about this rare but potential side effect of uniphyline. We suggest monitoring phosphate levels in patients admitted with acute respiratory failure especially those on extended bronchodilator therapy.

Application of fiberoptic bronchscopy in patients with acute exacerbations of chronic obstructive pulmonary disease during sequential weaning of invasive-noninvasive mechanical ventilation

BACKGROUND:Early withdrawal of invasive mechanical ventilation(IMV) followed by noninvasive MV(NIMV) is a new strategy for changing modes of treatment in patients with acute exacerbations of chronic obstructive pulmonary disease(AECOPD) with acute respiratory failure(ARF).Using pulmonary infection control window(PIC window) as the switch point for transferring from invasive to noninvasive MV,the time for early extubation can be more accurately judged,and therapy efficacy can be improved.This study aimed to prospectively investigate the clinical effectiveness of fiberoptic bronchscopy(FOB) in patients with AECOPD during sequential weaning of invasive-noninvasive MV.METHODS:Since July 2006 to January 2011,106 AECOPD patients with ARF were treated with comprehensive medication and IMV after hospitalization.Patients were randomly divided into two groups according to whether fiberoptic bronchoscope is used(group A,n=54) or not(group B,n=52) during sequential weaning from invasive to noninvasive MV.In group A,for sputum suction and bronchoalveolar lavage(BAL),a fiberoptic bronchoscope was put into the airway from the outside of an endotracheal tube,which was accompanied with uninterrupted use of a ventilator.After achieving PIC window,patients of both groups changed to NIMV mode,and weaned from ventilation.The following listed indices were used to compare between the groups after treatment:1) the occurrence time of PIC,the duration of MV,the length of ICU stay,the success rate of weaning from MV for the first time,the rate of reventilatJon and the occurrence rate of ventilator-associated pneumonia(VAP);2) the convenience and safety of FOB manipulation.The results were compared using Student's f test and the Chi-square test.RESULTS:The occurrence time of PIC was(5.01 ±1.49) d,(5.87±1.87) d in groups A and B,respectively(P<0.05);the duration of MV was(6.98±1.84) d,(8.69±2.41) d in groups A and B,respectively(P<0.01);the length of ICU stay was(9.25±1.84) d,(11.10±2.63) d in groups A and B,respectively(P<0.01);the success rate of weaning for the first time was 96.30%,76.92%in groups A and B,respectively(P<0.01);the rate of reventilation was 5.56%,19.23%in groups A and B,respectively(P<0.05);and the occurrence rate of VAP was 3.70%,23.07%in groups A and B,respectively(P<0.01).Moreover,it was easy and safe to manipulate FOB,and no side effect was observed.CONCLUSIONS:The application of FOB in patients with AECOPD during sequential weaning of invasive-noninvasive MV is effective in ICU.It can decrease the duration of MV and the length of ICU stay,increase the success rate from weaning MV for the first time,reduce the rate of reventilation and the occurrence rate of VAP.In addition,such a method is convenient and safe in patients of this kind.

Lung ultrasound for the early diagnosis of acute lung injury:A case report

BACKGROUND The extensive availability of ultrasound(US)technology has increased its use for point-of-care applications in many health care settings.During anaesthesia and surgery,acute respiratory failure or pulmonary oedema are common lifethreatening events that,if not recognized and treated appropriately,result in a high mortality rate.CASE SUMMARY We report a patient under anaesthesia whose lung US examination showed multiple vertical artefacts(B-lines)in the lung tissue,indicating pulmonary oedema.The respiratory state improved with the resolution of the pulmonary oedema after our treatment.CONCLUSION We believe that US of the lungs may be a useful tool for dynamic respiratory monitoring at the bedside during anaesthesia.

A 60-Year-Male Post Corneal Transplantation with Acute Pneumonia

Pneumonia is a common complication in organ transplantation patients. Multiple respiratory pathogens such as bacteria, viruses and fungi are potentially coexisted. A 60-year-old male with left eye post corneal transplantation developed acute severe pneumonia caused by Pneumocystis jiroveci (PJP) coinfection with Nocardia spp. and Cytomegalovirus (CMV). He was hospitalized due to acute respiratory failure. Chest radiographs and chest Computed Tomography (CT) revealed extensive ground-glass opacities. PJP was diagnosed from Bronchoalveolar Lavage Fluid (BALF). The pneumonia was persistent despite of receiving intravenous cotrimoxazole. Tracheal aspirate showed faint gram-positive filamentous beaded branching organisms. Consequently Nocardia spp. was proven. Intravenous cotrimoxazole was continued and intravenous imipenem was added. After a course of dual antibiotics, pneumonia was gradually improved. A week after, he developed the worsened acute respiratory failure. The bronchoscopy was performed. The new pathogens were not detected from BALF microbiology. The BALF cytology was unremarkable. PJP was detected by Polymerase Chain Reaction (PCR) from BALF. CMV antigenemia was detected from BALF and blood. Intravenous ganciclovir was given. This report describes PJP coinfected with Nocardia spp. and CMV in post corneal transplantation patient suffering from severe pneumonia. Multiple respiratory pathogens are common among transplantation patients representing host immunosuppression and inadequate antimicorbial prophylaxis.

Non-invasive versus invasive mechanical ventilation for respiratory failure in severe acute respiratory syndrome

Background Severe acute respiratory syndrome is frequently complicated by respiratory failure requiring ventilatory support.We aimed to compare the efficacy of non-invasive ventilation against invasive mechanical ventilation treating respiratory failure in this disease.Methods Retrospective analysis was conducted on all respiratory failure patients identified from the Hong Kong Hospital Authority Severe Acute Respiratory Syndrome Database.Intubation rate,mortality and secondary outcome of a hospital utilizing non-invasive ventilation under standard infection control conditions(NIV Hospita1)were compared against 13 hospitals using solely invasive ventilation(IMV Hospitals).Multiple logistic regression analyses with adjustments for confounding variables were performed to test for association between outcomes and hospital groups.Results Both hospital groups had comparable demographics and clinical profiles,but NIV Hospital(42 patients)had higher lactate dehydrogenase ratio and worse radiographic score on admission and ribavirin-corticosteroid commencement.Compared to IMV Hospitals(451 patients).NIV Hospital had lower adjusted odds ratios for intubation(0.36,95%C10.164-0.791,P=0.011)and death(0.235.95%C10.077-0.716,P=0.O 11),and improved earlier after pulsed steroid rescue.There were no instances of transmission of severe acute respiratory syndrome among health care workers due to the use of non-invasive ventilation.Conclusion Compared to invasive mechanical ventilation,non-invasive ventilation as initial ventilatory support for acute respiratory failure in the presence of severe acute respiratory syndrome appeared to be associated with reduced intubation need and mortality.

High-flow nasal cannula oxygen therapy in acute hypoxemic respiratory failure and COVID-19-related respiratory failure

Although standard oxygen face masks are first-line therapy for patients with acute hypoxemic respiratory failure,high-flow nasal cannula oxygen therapy has gained major popularity in intensive care units.The physiological effects of high-flow oxygen counterbalance the physiological consequences of acute hypoxemic respiratory failure by lessening the deleterious effects of intense and prolonged inspiratory efforts generated by patients.Its simplicity of application for physicians and nurses and its comfort for patients are other arguments for its use in this setting.Although clinical studies have reported a decreased risk of intubation with high-flow oxygen compared with standard oxygen,its survival benefit is uncertain.A more precise definition of acute hypoxemic respiratory failure,including a classification of severity based on oxygenation levels,is needed to better compare the efficiencies of different non-invasive oxygenation support methods(standard oxygen,high-flow oxygen,and non-invasive ventilation).Additionally,the respective role of each non-invasive oxygenation support method needs to be established through further clinical trials in acute hypoxemic respiratory failure,especially in severe forms.

Critically ill patients with cancer: A clinical perspective

Cancer patients account for 15%of all admissions to intensive care unit(ICU)and 5%will experience a critical illness resulting in ICU admission.Mortality rates have decreased during the last decades because of new anticancer therapies and advanced organ support methods.Since early critical care and organ support is associated with improved survival,timely identification of the onset of clinical signs indicating critical illness is crucial to avoid delaying.This article focused on relevant and current information on epidemiology,diagnosis,and treatment of the main clinical disorders experienced by critically ill cancer patients.

Principles of Diagnosis and Treatment of Patients with Diagnosis of Covid-19 and Developing Viral Pneumonia

The article provides information on our achievements in the application of modern diagnostic methods and modern methods of treating patients with viral pneumonia,confirmed by covid-19.For this,statistical data of 2,000 patients were used.Of the 2,000 patients treated,920 were men,1,070 were women and 10 were children.Viral pneumonia-glaucoma syndrome in 1650 out of 2,000 patients with 10-20%damage;In 350,the diagnosis of viral pneumonia-frostbite syndrome with 50-85%damage,CRDS,respiratory failure was confirmed.Thus,50 out of 350 patients treated at the intensive care unit(ICU)out of 2,000 were intubated and connected to artificial ventilation.The research was carried out in 3 stages:I stage-admission to the intensive care unit;II stage-from the day of intubation to spontaneous breathing(7-14 days);and III stage-covers the period of extubation and recovery.The results of clinical,functional,hemodynamic and echocardiographic studies of the patients participating in the examination were analyzed.Also,the patients underwent bacteriological research studied the sensitivity to antibiotics.In addition,the composition of blood gases and the oxygenation index-Carrico were studied.

Histopathological Analysis about Autopsies from HIV/AIDS Patients—About Two Decades of Research Comparing Results before and after Antiretroviral Therapy Advent

Objectives: This study considers 489 autopsies of HIV/AIDS patients who died from acute respiratory failure and describes the demographic data, etiology, and histological pulmonary findings of HIV associated diseases, comparing results before and after introduction of antiretroviral therapy. Methods: The following data were obtained: age, sex, and major associated diseases (found at the autopsy). Pulmonary histopathology was categorized as: diffuse alveolar damage;pulmonary edema;alveolar hemorrhage;and acute interstitial pneumonia. Odds ratio of the HIV/AIDS-associated diseases developing a specific histopathological pattern was determined by logistic regression. Results: A total of 355 men were studied. The mean age was 37 years old. Bronchopneumonia presented in 43% and Pneumocystis jiroveci pneumonia in 38% of patients. Pulmonary histopathology showed diffuse alveolar damage in 31% and acute interstitial pneumonia in 23%. The multivariate analysis showed a significant and positive association between diffuse alveolar damage with disseminated tuberculosis, cirrhosis and sepsis;and acute interstitial pneumonia with Pneumocystis jiroveci pneumonia and cytomegalovirosis. After the introduction of antiretroviral therapy we observed an increase in the prevalence of bacterial bronchopneumonia, sepsis and cirrhosis;and a decrease in Pneumocystis jiroveci pneumonia and cytomegalovirosis. Conclusions: Coherent to literature, this study showed a decrease of respiratory failure mortality associated with some opportunistic infections after antiretroviral therapy introduction. But an increased prevalence of sepsis, bronchopneumonia and sepsis was observed too. The most prevalent pulmonary histopathological pattern was diffuse alveolar damage, which suggested a positive association with disseminated tuberculosis, sepsis and cirrhosis.

Nephrogenic acute respiratory distress syndrome： A narrative review on pathophysiology and treatment

The kidneys have a close functional relationship with other organs especially the lungs. This connection makes the kidney and the lungs as the most organs involved in the multi-organ failure syndrome. The combination of acute lung injury （ALl） and renal failure results a great clinical significance of 80% mortality rate. Acute kidney injury （AKI） leads to an increase in circulating cytokines, chemokines, activated innate immune cells and diffuse of these agents to other organs such as the lungs. These factors initiate pathological cascade that ultimately leads to ALl and acute respiratory distress syndrome （ARDS）. We comprehensively searched the English medical literature focusing on AKI, ALl, organs cross talk, renal failure, multi organ failure and ARDS using the databases of PubMed, Embase, Scopus and directory of open access journals. In this narrative review, we summarized the pathophysiology and treatment of respiratory distress syndrome following AKI. This review promotes knowledge of the link between kidney and lung with mechanisms, diagnostic biomarkers, and treatment involved ARDS induced by AKI.

Effectiveness and safety of noninvasive positive-pressure ventilation for severe hypercapnic encephalopathy due to acute exacerbation of chronic obstructive pulmonary disease:a prospective case-control study

Background Although severe encephalopathy has been proposed as a possible contraindication to the use of noninvasive positive-pressure ventilation （NPPV）, increasing clinical reports showed it was effective in patients with impaired consciousness and even coma secondary to acute respiratory failure, especially hypercapnic acute respiratory failure （HARF）. To further evaluate the effectiveness and safety of NPPV for severe hypercapnic encephalopathy, a prospective case-control study was conducted at a university respiratory intensive care unit （RICU） in patients with acute exacerbation of chronic obstructive pulmonary disease （AECOPD） during the past 3 years. Methods Forty-three of 68 consecutive AECOPD patients requiring ventilatory support for HARF were divided into 2 groups, which were carefully matched for age, sex, COPD course, tobacco use and previous hospitalization history, according to the severity of encephalopathy, 22 patients with Glasgow coma scale （GCS） 〈10 served as group A and 21 with GCS 〉10 as group B. Results Compared with group B, group A had a higher level of baseline arterial partial CO2 pressure （（102±27） mmHg vs （74±17） mmHg, P〈0.01）, lower levels of GCS （7.5±1.9 vs 12.2±1.8, P〈0.01）, arterial pH value （7.18±0.06 vs 7.28±0.07, P〈0.01） and partial 02 pressure/fraction of inspired 02 ratio （168±39 vs 189±33, P〈0.05）. The NPPV success rate and hospital mortality were 73% （16/22） and 14% （3/22） respectively in group A, which were comparable to those in group B （68% （15/21） and 14% （3/21） respectively, all P〉0.05）, but group A needed an average of 7 cmH20 higher of maximal pressure support during NPPV, and 4, 4 and 7 days longer of NPPV time, RICU stay and hospital stay respectively than group B （P〈0.05 or P〈0.01）. NPPV therapy failed in 12 patients （6 in each group） because of excessive airway secretions （7 patients）, hemodynamic instability （2）, worsening of dyspnea and deterioration of gas exchange （2）, and gastric content aspiration （1）. Conclusions Selected patients with severe hypercapnic encephalopathy secondary to HARF can be treated as effectively and safely with NPPV as awake patients with HARF due to AECOPD; a trial of NPPV should be instituted to reduce the need of endotracheal intubation in patients with severe hypercapnic encephalopathy who are otherwise good candidates for NPPV due to AECOPD.

Performance of Multiple Risk Assessment Tools to Predict Mortality for Adult Respiratory Distress Syndrome with Extracorporeal Membrane Oxygenation Therapy： An External Validation Study Based on Chinese Single-center Data

Background： There has been no external validation of survival prediction models for severe adult respiratory distress syndrome （ARDS） with extracorporeal membrane oxygenation （ECMO） therapy in China. The aim of study was to compare the performance of multiple models recently developed for patients with ARDS undergoing ECMO based on Chinese single-center data. Methods： A retrospective case study was performed, including twenty-three severe ARDS patients who received ECMO from January 2009 to July 2015. The PRESERVE （Predicting death for severe ARDS on VV-ECMO）, ECMOnet, Respiratory Extracorporeal Membrane Oxygenation Survival Prediction （RESP） score, a center-specific model developed lbr inter-hospital transfers receiving ECMO, and the classical risk-prediction scores of Acute Physiology and Chronic Health Evaluation （APACHE） II and Sequential Organ Failure Assessment （SOFA） were calculated. In-hospital and six-month mortality were regarded as the endpoints and model performance was evaluated by comparing the area under the receiver operating characteristic curve （AUC）. Results： The RESP and APACHE II scores showed excellent discriminate performance in predicting survival with AUC of 0.835 （95% confidence interval [CI], 0.659-1 .010, P = 0.007） and 0.762 （95% CI, 0.558-0.965, P = 0.035）, respectively. The optimal cutoff values were risk class 3.5 for RESP and 35.5 for APACHE II score, and both showed 70.0% sensitivity and 84.6% specificity. The excellent performance of these models was also evident for the pneumonia etiological subgroup, for which the SOFA score was also shown to be predictive, with an AUC of 0.790 （95% CI, 0.571-1.009, P = 0.038）. However, the ECMOnet and the score developed for externally retrieved ECMO patients failed to demonstrate significant discriminate power for the overall cohort. The PRESERVE model was unable to be evaluated fully since Conclusions： The RESP, APCHAE 11, and SOFA scorings only one patient died six months postdischarge. systems show good predictive value for intra-hospital survival of ARDS patients treated with ECMO in our single-center evaluation. Future validation should include a larger study with either more patients＇ data at single-center or by integration of domestic multi-center data. Development of a scoring system with national characteristics might be warranted.

Hygrometry behavior during high-flow nasal oxygen therapy and non-invasive mechanical ventilation:A narrative review of bench to clinical studies

Recently,there has been growing interest in knowing the best hygrometry level during high-flow nasal oxygen and non-invasive ventilation(NIV)and its potential influence on the outcome.Various studies have shown that breathing cold and dry air results in excessive water loss by nasal mucosa,reduced mucociliary clearance,in-creased airway resistance,reduced epithelial cell function,increased inflammation,sloughing of tracheal epithe-lium,and submucosal inflammation.With the Coronavirus Disease 2019 pandemic,using high-flow nasal oxygen with a heated humidifier has become an emerging form of non-invasive support among clinicians.However,we cannot always assume stable humidification.Similarly,there are no clear guidelines for using humidification dur-ing NIV,although humidification of inspired gas during invasive ventilation is an accepted standard of care.NIV disturbs the normal physiological system that warms and humidifies inspired gases.If NIV is supplied through an intensive care unit ventilator that utilizes anhydrous gases from compressed wall air and oxygen,the risk of dry-ness increases.In addition,patients with acute respiratory failure tend to breathe through the mouth during NIV,which is a less efficient route than nasal breathing for adding heat and moisture to the inspired gas.Obstructive sleep apnea syndrome is one of the most important indications for chronic use of NIV at home.Available data suggest that up to 60%of patients with obstructive sleep apnea syndrome who use continuous positive airway pressure therapy experience nasal congestion and dryness of the mouth and nose.Therefore,humidifying the inspired gas in NIV may be essential for patient comfort and compliance with treatment.We aimed to review the available bench and clinical studies that addressed the utility of hygrometry in NIV and nasal high-flow oxygen and discuss the technical limitations of different humidification systems for both systems.