Short-term effects of a nicotine-free e-cigarette compared to a traditional cigarette in smokers and non-smokers

BACKGROUND: A few studies have assessed the short-term effects of low-dose nicotine e-cigarettes, while data about nicotine-free e-cigarettes (NF e-cigarettes) are scanty. Concerns have been expressed about the use of NF e-cigarettes, because of the high concentrations of propylene glycol and other compounds in the e-cigarette vapor. METHODS: This laboratory-based study was aimed to compare the effects of ad libitum use of a NF e-cigarette or and a traditional cigarette for 5 min in healthy adult smokers (n\u2009=\u200910) and non-smokers (n\u2009=\u200910). The main outcome measures were pulmonary function tests, fraction of exhaled nitric oxide (FeNO) and fractional concentration of carbon monoxide (FeCO) in exhaled breath. RESULTS: The traditional cigarette induced statistically significant increases in FeCO in both smokers and non-smokers, while no significant changes were observed in FeNO. In non-smokers, the traditional cigarette induced a significant decrease from baseline in FEF75 (81 %\u2009\ub1\u200935 % vs 70.2 %\u2009\ub1\u200928.2 %, P\u2009=\u20090.013), while in smokers significant decreases were observed in FEF25 (101.3 %\u2009\ub1\u200916.4 % vs 93.5 %\u2009\ub1\u200931.7 %, P\u2009=\u20090.037), FEV1 (102.2 %\u2009\ub1\u20099.5 % vs 98.3 %\u2009\ub1\u200910 %, P\u2009=\u20090.037) and PEF (109.5 %\u2009\ub1\u200914.6 % vs 99.2 %\u2009\ub1\u200917.5 %, P\u2009=\u20090.009). In contrast, the only statistically significant effects induced by the NF e-cigarette in smokers were reductions in FEV1 (102.2 %\u2009\ub1\u20099.5 % vs 99.5\u2009\ub1\u20097.6 %, P\u2009=\u20090.041) and FEF25 (103.4 %\u2009\ub1\u200916.4 % vs 94.2 %\u2009\ub1\u200916.2 %, P\u2009=\u20090.014). DISCUSSION: The present study demonstrated that the specific brand of NF e-cigarette utilized did not induce any majoracute effects. In contrast, several studies have shown that both traditional cigarettes and nicotine-containing e-cigarettes have acute effects on lung function. Our study expands on previous observations on the effects of NF e-cigarettes, but also for the first time describes the changes induced by smoking one traditional cigarette in a group of never smokers. CONCLUSIONS: The short-term use of the specific brand of NF e-cigarette assessed in this study had no immediate adverse effects on non-smokers and only small effects on FEV1 and FEF25 in smokers. The long-term health effects of NF e-cigarette use are unknown but worthy of further investigations. TRIAL REGISTRATION: Clinicaltrials.gov: NCT02102191

Patient-ventilator interaction during noninvasive positive pressure ventilation

The interaction between the patient and the ventilator is complex,especially in a "semi-open" system as for noninvasive ventilation(NIV). Air leaks around the mask are likely to occur, and they affect patient-ventilator synchrony. Several variables may be responsible for the mismatch between the start of the neural output and that of ventilatory aid during NIV. The most common mode of ventilation is pressure support ventilation (PSV), which may result in a number of inspiratory efforts not being followed by ventilator aid. New modes of ventilation, such as proportional assist ventilation, maybe useful in improving patient tolerance to ventilation without affecting clinical outcome. The ventilatory settings are important during PSV to determine the synchrony. The inspiratory trigger function may be influenced by the amount of leaks, whereas a better synchrony may be achieved if the termination of the inspiratory phase is time cycled instead of flow cycled. A high pressurization rate results in poor compliance. Care should be paid in the choice of the interfaces because leaks in the system are associated with a substantial breath-to-breath inspiratory variation independent from the patient effort. Last, NIV should be delivered with turbine- or piston-based ventilators that are able to compensate for air leaks. With respect to the problem of sedation, we point out the importance of optimizing the environmental conditions, avoiding excessive light and noise, assuring patient comfort, and providing reassurance. When sedation is needed, we suggest the use of low doses of analgesics and neuroleptic agents in selected cases

Causes of failure of noninvasive mechanical ventilation

With selected patients noninvasive positive-pressure ventilation (NPPV) can obviate endotracheal intubation and thus avoid the airway trauma and infection associated with intubation. With patients who can cooperate, NPPV is the first-line treatment for mild-to-severe acute hypercapnic respiratory failure. NPPV is also used for hypercapnic ventilatory failure and to assist weaning from mechanical ventilation, by allowing earlier extubation. Some patients do not obtain adequate ventilation with NPPV and therefore require intubation. Also, some patients will initially benefit from NPPV (for one-to-several days) but will then deteriorate and require intubation. It is not always apparent which patients will initially benefit from NPPV, so researchers have been looking for variables that predict NPPV success/failure. The reported NPPV failure rate is 5-40%, so the necessary staff and equipment for prompt intubation should be readily available. Absolute contraindications to NPPV are: cardiac or respiratory arrest; nonrespiratory organ failure (eg, severe encephalopathy, severe gastrointestinal bleeding, hemodynamic instability with or without unstable cardiac angina); facial surgery or trauma; upper-airway obstruction; inability to protect the airway and/or high risk of aspiration; and inability to clear secretions. The NPPV training and experience of the clinician team partly determines whether the patient will succeed with NPPV or, instead, require intubation. Greater clinician-team NPPV experience and expertise are associated with a higher percentage of patients succeeding on NPPV and with NPPV success with sicker patients (than will succeed with a less-experienced clinician team). With patients suffering hypercapnic respiratory failure the best NPPV success/failure predictor is the degree of acidosis/acidemia (pH and P(aCO(2)) at admission and after 1 hour on NPPV), whereas mental status and severity of illness are less reliable predictors. With patients suffering hypoxic respiratory failure the likelihood of NPPV success seems to be related to the underlying disease rather than to the degree of hypoxia. For example, the presence of acute respiratory distress syndrome or community-acquired pneumonia portends NPPV failure, as does lack of oxygenation improvement after an hour on NPPV. All the proposed NPPV success/failure predictors should be used cautiously and need further study. We predict that further study and team experience will improve the NPPV success rate and allow successful NPPV-treatment of sicker patients

Physiotherapy and weaning from prolonged mechanical ventilation

BACKGROUND: Patients undergoing prolonged mechanical ventilation represent up to 15% of all patients requiring weaning from mechanical ventilation. Although recent guidelines have recommended including physiotherapy early during mechanical ventilation to speed the process of weaning, only indirect evidence supporting the use of physiotherapy is available for patients receiving prolonged mechanical ventilation. The aim of our study was to evaluate the effects of a physiotherapy program in subjects requiring prolonged mechanical ventilation and the correlates of successful weaning. METHODS: A retrospective analysis was performed on 1,313 consecutive patients admitted to a weaning unit over a 15-y period to be liberated from prolonged mechanical ventilation. Subjects underwent a program of intensive physiotherapy organized in 4 incremental steps (1\u20134) and were analyzed according to the steps achieved (> 2 steps or 64 2 steps). The rate of successful weaning was recorded, and possible predictors were considered. The 15-y period of observation was divided into 3 consecutive 5-y intervals. RESULTS: Out of 560 subjects undergoing final analysis, 349 (62.3%) were successfully weaned. The weaning success rate was significantly greater in subjects attaining > 2 steps than in subjects who attained 64 2 steps (72.1% vs 55.9%, respectively, odds ratio = 2.04, 95% CI = 1.42\u20132.96, P 2 physiotherapy steps was the main predictor of successful weaning (odds ratio = 2.17, 95% CI = 1.48\u20133.23, P <.001). Underlying disease was also a predictor of successful weaning. The overall rate of successful weaning decreased, and the median duration of weaning increased, during the period of observation. CONCLUSIONS: Our data support the inclusion of physiotherapy in the management of patients requiring prolonged mechanical ventilation

Physiological responses during a T-piece weaning trial with a deflated tube

RATIONALE: T-piece trials and spontaneous breathing trials through the tracheostomy tube are often used as weaning techniques. They are usually performed with the cuff inflated, which may increase the inspiratory load and/or influence the tidal volume generated by the patient. We assessed diaphragmatic effort during T-piece trials with or without cuff inflation. SETTINGS: Respiratory intensive care unit METHODS: We measured breathing pattern, transdiaphragmatic pressure (Pdi), the pressure-time product of the diaphragm, per minute (PTPdi/min) and per breath (PTPdi/b), and lung mechanics (lung compliance and resistance) in 13 tracheotomized patients ready for a weaning trial. V(T) was recorded with respiratory inductive plethysmography (RIP-V(T)) or pneumotachography PT-V(T)). Patients completed two T-piece trials of 30[Symbol: see text]min each with or without the cuff inflated. RESULTS: RIP-V(T) and PT-V(T) values were similar with the cuff inflated, but PT-V(T) significantly underestimated RIP-V(T) when the cuff was deflated, and therefore the RIP-V(T) was chosen as the reference method. The RIP-V(T) was significantly greater and the Pdi and PTPdi/min significantly lower when the cuff was deflated than when it was inflated. The efficiency of the diaphragm, calculated by the ratio of PTPdi/b over RIP-V(T), was also improved, while no changes were observed in lung mechanics. CONCLUSIONS: Diaphragmatic effort is significantly lower during a T-piece trial with a deflated cuff than when the cuff is inflated, while RIP-V(T) is higher, so that the diaphragm's efficiency in generating tidal volume is also improved