Increased airway resistance among exclusive waterpipe smokers detected using impulse oscillometry.

INTRODUCTION: Waterpipe smoking is increasing in popularity, yet the evidence implicating waterpipe smoking in lung disease is limited. We hypothesized that impulse oscillometry (IOS) would detect airway abnormalities in waterpipe smokers (WPS). METHODS: We studied 210 participants, 40 years or older, from the community, of whom 92 were exclusive WPS and 118 were never-smokers. Waterpipe smoking history was assessed using a validated questionnaire. All participants underwent spirometry, and IOS and absolute and percentage predicted results (for age, sex, height, and weight) were compared between WPS and nonsmokers. The association of IOS parameters with waterpipe smoking duration and extent (waterpipe smoked/day * smoking duration) was evaluated using linear regression. RESULTS: WPS smoked on average 1.8 ± 1.2 waterpipes/day, over an average duration of 23.3 ± 39.8 years. WPS and nonsmokers were largely asymptomatic and had similar age, body mass index, sex distribution, and spirometric values. Nevertheless, WPS had higher IOS measured resistance at 5Hz compared to nonsmokers, (0.53 ± 0.2 vs. 0.48 ± 0.2 kPa/L/s, P = 0.03) and higher percentage-predicted resistance (124.5 ± 36.3 vs. 115.7% ± 35.6%, P = 0.04). Waterpipe smoking duration was also associated with resistance (ß = 0.04 kPa/L/s/year, P = 0.01) and with percentage-predicted resistance (ß = 0.05/year, P = 0.02). Waterpipe smoking extent was associated with resistance (ß = 0.009 kPa/L/s/waterpipe-year, P = 0.04), while the association with percentage-predicted resistance was near significance (ß = 0.009/waterpipe-year, P = 0.07). CONCLUSIONS: Waterpipe smoking is associated with increased airway resistance assessed by IOS but not by spirometry in largely asymptomatic individuals from the community.

A Survey on the Knowledge, Attitudes, and Practices of Lebanese Physicians Regarding Air Pollution.

INTRODUCTION: Air pollution imposes a significant burden on public health. It is emerging as a modifiable risk factor for cancer, diabetes, and respiratory and cardiovascular diseases. This study aims to assess the knowledge, attitudes, and practices of Lebanese physicians regarding air pollution. METHODS: This observational study uses a descriptive cross-sectional correlational design. The data were collected using a self-administered online survey that was sent to 874 potential respondents who are members of the Lebanese Order of Physicians. Data analysis was done using descriptive statistics and a chi-square test. RESULTS: The results show a deficiency in the knowledge of physicians regarding many sources of air pollution, including dust, the smell of perfume, candles, vacuum cleaners, air fresheners, electronic cigarettes, etc. The majority of physicians agree that air pollution increases the risk of several health problems. Only 38% of physicians routinely ask their patients about exposure to air pollution, and 75% of them believe that they have a role as physicians in reducing air pollution levels. Over half of the sample are confident in counseling their patients on sources of air pollution, and two thirds of them are in support of including assessment of air pollution exposure during regular medical visits. CONCLUSION: Air pollution levels are progressively increasing over time. Given the health impact of exposure to air pollution, healthcare professionals need to stay up to date on this topic. The results of this study suggest the need for continuing education about air pollution for physicians and developing guidelines for what exactly to ask patients in assessing their exposure.

Burnout among postgraduate medical trainees in Lebanon: Potential strategies to promote wellbeing.

Objective: Burnout is a widespread issue in healthcare for many years. Lebanon combatted political and economic crises before the coronavirus disease 2019 (COVID-19) pandemic, in addition to the port explosion in August 2020. The study aimed to identify the determinants of personal burnout, patient-related burnout, and work-related burnout among postgraduate medical trainees (PGMT) and evaluate its relationship with sociodemographic characteristics. Design: A cross-sectional study utilized the Copenhagen Burnout Inventory (CBI) involving electronic, voluntary, and anonymous survey. The survey was completed by 188 PGMT including residents and fellows from all specialties and all levels of training. Results: The prevalence rates are 68.6% for personal burnout, 63.3% for work-related burnout, and 35.1% for patient-related burnout. Conclusion: Results improve our understanding of the phenomenon of burnout, and the role of program leadership in shaping the impact of burnout on training and promoting wellbeing of PGMT. Discussion focuses on providing potential wellbeing strategies for program directors to follow for mitigating burnout.

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.

Integrative Transcriptome Analyses Empower the Anti-COVID-19 Drug Arsenal.

The beginning of the 21st century has been marked by three distinct waves of zoonotic coronavirus outbreaks into the human population. The COVID-19 (coronavirus disease 2019) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and emerged as a global threat endangering the livelihoods of millions worldwide. Currently, and despite collaborative efforts, diverse therapeutic strategies from ongoing clinical trials are still debated. To address the need for such an immediate call of action, we leveraged the largest dataset of drug-induced transcriptomic perturbations, public SARS-CoV-2 transcriptomic datasets, and expression profiles from normal lung transcriptomes. Most importantly, our unbiased systems biology approach prioritized more than 50 repurposable drug candidates (e.g., corticosteroids, Janus kinase and Bruton kinase inhibitors). Further clinical investigation of these FDA-approved candidates as monotherapy or in combination with an antiviral regimen (e.g., remdesivir) could lead to promising outcomes in patients with COVID-19.

Structure and evaluation of a residency research program in a university hospital.

BACKGROUND: Most academic medical institutions lack a structured program that provides residents with an in-depth research training. The objectives of this paper are to describe a comprehensive residency research program at a university hospital, and to assess the pre- post-self-assessment of research capabilities of resident for the evaluation of the program. METHODS: The residency research program (RRP) was implemented in 2011 as an essential component of the residency program at the American University of Beirut Medical Center. Categorical residents are required to carry out a research project and go through all the steps of the research process from identifying a topic to writing a manuscript. As for evaluating the program, data were collected from residents who graduated between 2014 and 2016 using a questionnaire, which included the overall evaluation of the program, self-assessment on research-related tasks pre- and post- joining the program, as well as general recommendations. The mean scores on the five-point Likert scale were transformed into percentages (0-100%). The average was calculated and the difference in the means was reported. RESULTS: Overall, 103 residents from the different clinical departments were included in this study. Residents' self-assessment showed a 19.3% improvement in research-related tasks before and after completion of the RRP (P < 0.0001). Most of the residents have either published or are in the process of publishing their projects (34 and 55.3%, respectively). Time management was the most reported challenge. Generally, the program was evaluated positively. CONCLUSION: The RRP is a unique, well-structured program, encompassing residents from various clinical departments, which enhances residents' research capabilities.

The Effect of Preoperative Pneumonia on Postsurgical Mortality and Morbidity: A NSQIP Analysis.

BACKGROUND: Currently, only indirect evidence suggests that preoperative pneumonia is a significant risk factor for poor postsurgical outcomes. Although this relationship is clinically intuitive, this is the first study that aims to quantify the extent to which pneumonia impacts morbidity and mortality. The objective of this study was to determine the impact of preoperative pneumonia on 30-day mortality and morbidity among both elective and emergency surgical patients. METHODS: We conducted a retrospective cohort study using 2008-2012 data from the American College of Surgeons National Surgical Quality Improvement Program database. Patients with preoperative pneumonia were matched to controls without preoperative pneumonia. Patient demographics and postoperative outcomes were extracted from the database, including 30-day mortality, specific morbidities (wound, cardiac, respiratory, urinary, central nervous system, thromboembolism and sepsis), composite morbidity, number of blood transfusions and number of patients that returned to the OR. Mortality and composite morbidity were further stratified. RESULTS: We obtained data for 137,174 patients, of whom 6933 (0.50%) had preoperative pneumonia. Overall, 6111 were successfully matched to 24,444 patients with no pneumonia. Postoperative mortality and composite morbidity were both higher in patients with pneumonia than in those without pneumonia, with an odds ratio of 1.37 (95% CI 1.26-1.48) and 1.68 (95% CI 1.58-1.79), respectively. CONCLUSION: Preoperative pneumonia significantly increased the rate of postoperative morbidity and mortality across several surgical settings and patient groups. It is our recommendation that elective surgery be delayed until after the pneumonia resolves.

Joint statement for the diagnosis, management, and prevention of chronic obstructive pulmonary disease for Gulf Cooperation Council countries and Middle East-North Africa region, 2017.

Smoking and subsequent development of COPD is an ever-increasing epidemic in Arabian Gulf and Middle East countries, with no signs of decline. The important fact to be highlighted is that this COPD epidemic of increasing incidence and prevalence is mostly unrecognized by patients, due to the common attribution of symptoms to "smoker's cough", and the underdiagnosis and undertreatment by physicians because the common signs and symptoms masquerade as asthma. Consequently, there are long-term adverse effects of missing the diagnosis. The purpose of this review article is to focus upon the status of COPD in Arabian Gulf and Middle East countries, stressing the increasing burden of smoking and COPD, to emphasize the specific factors leading to rise in prevalence of COPD, to bring to light the underdiagnosis and undermanagement of COPD, and to treat COPD in conformity with standard guidelines with local and regional modifications. This review ends with suggestions and recommendations to the health department to formulate policies and to generate awareness among the general public about the side effects of smoking and consequences of COPD.

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.

ESOPHAGEAL PERFORATION FOLLOWING OROGASTRIC SUCTION CATHETER INSERTION IN AN ELDERLY PATIENT.

Esophageal rupture has been described following iatrogenic manipulation. In this report, we present an elderly lady admitted to the operative theater for laparoscopic cholecystectomy. Multiple intra-operative attempts to place a flexible orogastric tube were unsuccessful because of failure to advance. Post-operatively, the patient developed sepsis and a right pleural effusion. She was transferred to the Intensive Care Unit and she was treated with antibiotics. Radiologic evaluation confirmed an esophago-pleural fistula. Surgical repair was urgently performed for closure of fistula and lung decortication. The patient recovered and was discharged home.

Smoking and the risk of mortality and vascular and respiratory events in patients undergoing major surgery.

IMPORTANCE: The effects of smoking on postoperative outcomes in patients undergoing major surgery are not fully established. The association between smoking and adverse postoperative outcomes has been confirmed. Whether the associations are dose dependent or restricted to patients with smoking-related disease remains to be determined. OBJECTIVE: To evaluate the association between current and past smoking on the risk of postoperative mortality and vascular and respiratory events in patients undergoing major surgery. DESIGN: Cohort study using the American College of Surgeons National Surgical Quality Improvement Program database. We obtained data on smoking history, perioperative risk factors, and 30-day postoperative outcomes. We assessed the effects of current and past smoking (>1 year prior) on postoperative outcomes after adjustment for potential confounders and effect mediators (eg, cardiovascular disease, chronic obstructive pulmonary disease, and cancer). We also determined whether the effects are dose dependent through analysis of pack-year quintiles. SETTING AND PARTICIPANTS: A total of 607,558 adult patients undergoing major surgery in non-Veterans Affairs hospitals across the United States, Canada, Lebanon, and the United Arab Emirates during 2008 and 2009. MAIN OUTCOMES AND MEASURES: The primary outcome measure was 30-day postoperative mortality; secondary outcome measures included arterial events (myocardial infarction or cerebrovascular accident), venous events (deep vein thrombosis or pulmonary embolism), and respiratory events (pneumonia, unplanned intubation, or ventilator requirement >48 hours). RESULTS: The sample included 125,192 current (20.6%) and 78,763 past (13.0%) smokers. Increased odds of postoperative mortality were noted in current smokers only (odds ratio, 1.17 [95% CI, 1.10-1.24]). When we compared current and past smokers, the adjusted odds ratios were higher in the former for arterial events (1.65 [95% CI, 1.51-1.81] vs 1.20 [1.09-1.31], respectively) and respiratory events (1.45 [1.40-1.51] vs 1.13 [1.08-1.18], respectively). No effects on venous events were observed. The effects of smoking mediated through smoking-related disease were minimal. The increased adjusted odds of mortality in current smokers were evident from a smoking history of less than 10 pack-years, whereas the effects of smoking on arterial and respiratory events were incremental with increased pack-years. CONCLUSIONS AND RELEVANCE: Smoking cessation at least 1 year before major surgery abolishes the increased risk of postoperative mortality and decreases the risk of arterial and respiratory events evident in current smokers. These findings should be carried forward to evaluate the value and cost-effectiveness of intervention in this setting. Our study should increase awareness of the detrimental effects of smoking-and the benefits of its cessation-on morbidity and mortality in the surgical setting.

Inflammatory and repair serum biomarker pattern: association to clinical outcomes in COPD.

BACKGROUND: The relationship between serum biomarkers and clinical expressions of COPD is limited. We planned to further describe this association using markers of inflammation and injury and repair. METHODS: We studied lung function, comorbidities, exercise tolerance, BODE index, and quality of life in 253 COPD patients and recorded mortality over three years. Serum levels of Interleukins 6,8 and16, tumor necrosis factor alpha (TNF α) [inflammatory panel], vascular endothelial growth factor (VEGF), and matrix metalloproteinase 9 (MMP-9) [injury and repair panel] and pulmonary and activation-regulated chemokine (PARC/CCL-18) and monocyte chemotactic protein 1 (MCP-1/CCL2) [chemoattractant panel] were measured. We related the pattern of the biomarker levels to minimal clinically important differences (MCID) using a novel visualization method [ObServed Clinical Association Results (OSCAR) plot]. RESULTS: Levels of the inflammatory markers IL-6, TNF α were higher and those of injury and repair lower (p < 0.01) with more advanced disease (GOLD 1 vs. 4). Using the OSCAR plot, we found that patients in the highest quartile of inflammatory and lowest quartile of injury and repair biomarkers level were more clinically compromised and had higher mortality (p < 0.05). CONCLUSIONS: In COPD, serum biomarkers of inflammation and repair are distinctly associated with important clinical parameters and survival.

Critical care clinicians' knowledge of evidence-based guidelines for preventing ventilator-associated pneumonia.

BACKGROUND: Ventilator-associated pneumonia is the most common hospital-acquired infection among patients receiving mechanical ventilation in an intensive care unit. Different initiatives for the prevention of ventilator-associated pneumonia have been developed and recommended. OBJECTIVE: To evaluate knowledge of critical care providers (physicians, nurses, and respiratory therapists in the intensive care unit) about evidence-based guidelines for preventing ventilator-associated pneumonia. METHODS: Ten physicians, 41 nurses, and 18 respiratory therapists working in the intensive care unit of a major tertiary care university hospital center completed an anonymous questionnaire on 9 nonpharmacological guidelines for prevention of ventilator-associated pneumonia. RESULTS: The mean (SD) total scores of physicians, nurses, and respiratory therapists were 80.2% (11.4%), 78.1% (10.6%), and 80.5% (6%), respectively, with no significant differences between them. Furthermore, within each category of health care professionals, the scores of professionals with less than 5 years of intensive care experience did not differ significantly from the scores of professionals with more than 5 years of intensive care experience. CONCLUSIONS: A health care delivery model that includes physicians, nurses, and respiratory therapists in the intensive care unit can result in an adequate level of knowledge on evidence-based nonpharmacological guidelines for the prevention of ventilator-associated pneumonia.

Metabolic and respiratory variables during pressure support versus synchronized intermittent mandatory ventilation.

BACKGROUND: Mechanically ventilated patients interact and respond differently to different modes of ventilatory support. OBJECTIVES: To assess changes in metabolic and respiratory variables during equivalent changes with either pressure support ventilation (PSV) or volume-cycled synchronized intermittent mandatory ventilation (SIMV) in non-tracheostomized patients without known obstructive pulmonary disease receiving short-term mechanical ventilation in the intensive care unit. METHODS: Fourteen patients receiving volume-cycled SIMV at 12 breaths/min (SIMV(100%)) were included in the study. The PSV level (PSV(100%)) resulting in a minute volume and respiratory rate equivalent to that during SIMV(100%) was determined for each patient. Then each patient underwent trials at 66% and 33% of initial ventilator support with volume-cycled SIMV (SIMV(66%) and SIMV(33%)) and PSV (PSV(66%) and PSV(33%)) in random order. At the end of each trial, oxygen consumption ((.)VO2), carbon dioxide production ((.)VCO2), measured energy expenditures (MEE), peak inspiratory flow, total respiratory frequency, tidal volume, minute ventilation, occlusion pressure (P(0.1)) and inspiratory duty cycle (T(i)/T(tot)) were measured. RESULTS: There were smaller changes in (.)VO2, (.)VCO2 and MEE when equivalent changes were applied with PSV (15.7 +/- 4.4; 12.5 +/- 2.2 and 15 +/- 3.5%) compared with volume-cycled SIMV (32.7 +/- 7.7; 23 +/- 5.2 and 30.7 +/- 6.8%; p < 0.05). P(0.1) and T(i)/T(tot) were significantly smaller during PSV (2.64 +/- 0.28 and 0.38 +/- 0.03 cm H(2)O) than volume-cycled SIMV (4.01 +/- 0.21 and 0.43 +/- 0.02 cm H2O; p < 0.05). CONCLUSIONS: Changes in the level of PSV resulted in smaller changes in metabolic and respiratory variables compared with equivalent changes in the level of volume-cycled SIMV support. PSV may be more suitable for progressive respiratory muscle reloading.

Effect of pressure support ventilation and positive end expiratory pressure on the rapid shallow breathing index in intensive care unit patients.

OBJECTIVE: We compared rapid shallow breathing index (RSBI) values under various ventilatory support settings prior to extubation. DESIGN AND SETTING: Prospective study in the intensive care unit at a university hospital. PATIENTS: Thirty six patients ready for extubation. INTERVENTIONS: Patients were enrolled when receiving pressure support ventilation (PSV) of 5 cmH2O, PEEP of 5 cmH2O, and FIO2 of 40% (PS). Subsequently each patient received a trial of PSV of 0 cmH2O, PEEP of 5 cmH2O, and FIO2 of 40% (CPAP), a trial of PSV of 0 cmH2O, PEEP of 5 cmH2O and FIO2 of 21% (CPAP-R/A), and a 1-minute spontaneously breathing room air trial off the ventilator (T-piece). Trials were carried out in random order. MEASUREMENTS AND RESULTS: Respiratory frequency (f) and tidal volume (VT) were measured during PS, CPAP, CPAP-R/A, and T-piece in all patients. RSBI (f/VT) was determined for each patient under all experimental conditions, and the average RSBI was compared during PS, CPAP, CPAP-R/A, and T-piece. RSBI was significantly smaller during PS (46+/-8 bpm/l), CPAP (63+/-13 bpm/l) and CPAP-R/A (67+/-14 bpm/l) vs. T-piece (100+/-23 bpm/l). There was no significant difference in RSBI between CPAP and CPAP-R/A. RSBI during CPAP and CPAP-R/A were significantly smaller than RSBI during T-piece. In all patients RSBI values were less than 105 bpm/l during PS, CPAP, and CPAP-R/A. However, during T-piece the RSBI increased to greater than 105bpm/l in 13 of 36 patients. CONCLUSIONS: In the same patient the use of PSV and/or PEEP as low as 5 cmH2O can influence the RSBI. In contrast, changes in FIO2 may have no effect on the RSBI.