Cesare Gregoretti

Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients*

Objective:Compared with standard medical therapy (SMT), noninvasive ventilation (NIV) does not reduce the need for reintubation in unselected patients who develop respiratory failure after extubation. The goal of this study was to assess whether early application of NIV, immediately after extubation, is effective in preventing postextubation respiratory failure in an at-risk population. Design:Multiple-center, randomized controlled study. Setting:Multiple hospitals. Patients:Ninety-seven consecutive patients with similar baseline characteristics, requiring >48 hrs of mechanical ventilation and considered at risk of developing postextubation respiratory failure (i.e., patients who had hypercapnia, congestive heart failure, ineffective cough and excessive tracheobronchial secretions, more than one failure of a weaning trial, more than one comorbid condition, and upper airway obstruction). Interventions:After a successful weaning trial, the patients were randomized to receive NIV for ≥8 hrs a day in the first 48 hrs or SMT. Primary outcome was the need for reintubation according to standardized criteria. Secondary outcomes were intensive care unit and hospital mortality, as well as time spent in the intensive care unit and in hospital. Measurements and Main Results:Compared with the SMT group, the NIV group had a lower rate of reintubation (four of 48 vs. 12 of 49; p = .027). The need for reintubation was associated with a higher risk of mortality (p < .01). The use of NIV resulted in a reduction of risk of intensive care unit mortality (−10%, p < .01), mediated by the reduction for the need of reintubation. Conclusions:NIV was more effective than SMT in preventing postextubation respiratory failure in a population considered at risk of developing this complication.

Physiologic evaluation of noninvasive mechanical ventilation delivered with three types of masks in patients with chronic hypercapnic respiratory failure

Objective The efficacy of noninvasive mechanical ventilation (NIMV) in improving breathing pattern and arterial blood gases (ABG) in hypercapnic patients has been well documented; however, little attention has been given to the choice of the interface and the ventilatory mode. We evaluated the effects of three types of masks and two modes of ventilation on patients’ ABG, breathing pattern, and tolerance to ventilation. Design Prospective randomized study. Setting Two respiratory weaning centers. Patients A total of 26 stable hypercapnic patients (pH, 7.38 ± 0.04; Paco2, 59.2. ± 10.9 torr) had not received NIMV and were affected by restrictive thoracic disease or obstructive pulmonary disease. Interventions Three 30-min runs of NIMV, delivered using volume-assisted (n = 13) or pressure-assisted modes of partial mechanical support (n = 13), were performed in random order with a full-face mask, a nasal mask, and nasal plugs. Measurements ABG, breathing pattern, and patients’ tolerance to ventilation. Main Results Compared with spontaneous breathing, the application of NIMV significantly improved ABG and minute ventilation, irrespective of the ventilatory mode, the underlying pathology or the type of mask. Overall, a nasal mask was better tolerated than the other two interfaces (p < .005 vs. nasal plugs and full-face mask). Paco2 was significantly lower (p < .01) with a full-face mask or nasal plugs than with a nasal mask (49.5 ± 9.4 torr, 49.7 ± 8 torr, and 52.4 ± 11 torr, respectively). Minute ventilation was significantly higher with a full-face mask than with a nasal mask because of an increase in tidal volume. No differences were observed in tolerance to ventilation, ABG, or breathing pattern, using assist control or pressure-assisted modes. Conclusions In this physiologic study, we have shown that in patients with hypercapnic respiratory failure, irrespective of the underlying pathology, the type of interface affects the NIMV outcome more than the ventilatory mode.

Protective Mechanical Ventilation during General Anesthesia for Open Abdominal Surgery Improves Postoperative Pulmonary Function

Background:The impact of intraoperative ventilation on postoperative pulmonary complications is not defined. The authors aimed at determining the effectiveness of protective mechanical ventilation during open abdominal surgery on a modified Clinical Pulmonary Infection Score as primary outcome and postoperative pulmonary function. Methods:Prospective randomized, open-label, clinical trial performed in 56 patients scheduled to undergo elective open abdominal surgery lasting more than 2 h. Patients were assigned by envelopes to mechanical ventilation with tidal volume of 9 ml/kg ideal body weight and zero-positive end-expiratory pressure (standard ventilation strategy) or tidal volumes of 7 ml/kg ideal body weight, 10 cm H2O positive end-expiratory pressure, and recruitment maneuvers (protective ventilation strategy). Modified Clinical Pulmonary Infection Score, gas exchange, and pulmonary functional tests were measured preoperatively, as well as at days 1, 3, and 5 after surgery. Results:Patients ventilated protectively showed better pulmonary functional tests up to day 5, fewer alterations on chest x-ray up to day 3 and higher arterial oxygenation in air at days 1, 3, and 5 (mmHg; mean ± SD): 77.1 ± 13.0 versus 64.9 ± 11.3 (P = 0.0006), 80.5 ± 10.1 versus 69.7 ± 9.3 (P = 0.0002), and 82.1 ± 10.7 versus 78.5 ± 21.7 (P = 0.44) respectively. The modified Clinical Pulmonary Infection Score was lower in the protective ventilation strategy at days 1 and 3. The percentage of patients in hospital at day 28 after surgery was not different between groups (7 vs. 15% respectively, P = 0.42). Conclusion:A protective ventilation strategy during abdominal surgery lasting more than 2 h improved respiratory function and reduced the modified Clinical Pulmonary Infection Score without affecting length of hospital stay.

New treatment of acute hypoxemic respiratory failure: Noninvasive pressure support ventilation delivered by helmet: A pilot controlled trial

OBJECTIVE To assess the efficacy of noninvasive pressure support ventilation (NPSV) using a new special helmet as first-line intervention to treat patients with hypoxemic acute respiratory failure (ARF), in comparison to NPSV using standard facial mask. DESIGN AND SETTING Prospective clinical pilot investigation with matched control group in three intensive care units of university hospitals. PATIENTS AND METHODS Thirty-three consecutive patients without chronic obstructive pulmonary disease and with hypoxemic ARF (defined as severe dyspnea at rest, respiratory rate >30 breaths/min, PaO2:FiO2 < 200, and active contraction of the accessory muscles of respiration) were enrolled. Each patient treated with NPSV by helmet was matched with two controls with ARF treated with NPSV via a facial mask, selected by simplified acute physiologic score II, age, PaO2/FiO2, and arterial pH at admission. Primary end points were the improvement of gas exchanges, the need for endotracheal intubation, and the complications related to NPSV. RESULTS The 33 patients and the 66 controls had similar characteristics at baseline. Both groups improved oxygenation after NPSV. Eight patients (24%) in the helmet group and 21 patients (32%) in the facial mask group (p = .3) failed NPSV and were intubated. No patients failed NPSV because of intolerance of the technique in the helmet group in comparison with 8 patients (38%) in the mask group (p = .047). Complications related to the technique (skin necrosis, gastric distension, and eye irritation) were fewer in the helmet group compared with the mask group (no patients vs. 14 patients (21%), p = .002). The helmet allowed the continuous application of NPSV for a longer period of time (p = .05). Length of stay in the intensive care unit, intensive care, and hospital mortality were not different. CONCLUSIONS NPSV by helmet successfully treated hypoxemic ARF, with better tolerance and fewer complications than facial mask NPSV.

Noninvasive positive pressure ventilation using a helmet in patients with acute exacerbation of chronic obstructive pulmonary disease : a feasibility study

BackgroundNoninvasive positive pressure ventilation (NPPV) with a facemask (FM) is effective in patients with acute exacerbation of their chronic obstructive pulmonary disease. Whether it is feasible to treat these patients with NPPV delivered by a helmet is not known. MethodsOver a 4-month period, the authors studied 33 chronic obstructive pulmonary disease patients with acute exacerbation who were admitted to four intensive care units and treated with helmet NPPV. The patients were compared with 33 historical controls treated with FM NPPV, matched for simplified acute physiologic score (SAPS II), age, Paco2, pH, and Pao2:fractional inspired oxygen tension. The primary endpoints were the feasibility of the technique, improvement of gas exchange, and need for intubation. ResultsThe baseline characteristics of the two groups were similar. Ten patients in the helmet group and 14 in the FM group (P = 0.22) were intubated. In the helmet group, no patients were unable to tolerate NPPV, whereas five patients required intubation in the FM group (P = 0.047). After 1 h of treatment, both groups had a significant reduction of Paco2 with improvement of pH; Paco2 decreased less in the helmet group (P = 0.01). On discontinuing support, Paco2 was higher (P = 0.002) and pH lower (P = 0.02) in the helmet group than in the control group. One patient in the helmet group, and 12 in the FM group, developed complications related to NPPV (P < 0.001). Length of intensive care unit stay, intensive care unit, and hospital mortality were similar in both groups. ConclusionsHelmet NPPV is feasible and can be used to treat chronic obstructive pulmonary disease patients with acute exacerbation, but it does not improve carbon dioxide elimination as efficiently as does FM NPPV.

Analgo-Sedation of Patients with Burns Outside the Operating Room

Following the initial resuscitation of burn patients, the pain experienced may be divided into a ‘background’ pain and a ‘breakthrough’ pain associated with painful procedures.While background pain may be treated with intravenous opioids via continuous infusion or patient-controlled analgesia (PCA) and/or less potent oral opioids, breakthrough pain may be treated with a variety of interventions. The aim is to reduce patient anxiety, improve analgesia and ensure immobilization when required. Untreated pain and improper sedation may result in psychological distress such as post-traumatic stress disorder, major depression or delirium.This review summarizes recent developments and current techniques in sedation and analgesia in non-intubated adult burn patients during painful procedures performed outside the operating room (e.g. staple removal, wound-dressing, bathing).Current techniques of sedation and analgesia include different approaches, from a slight increase in background pain therapy (e.g. morphine PCA) to PCA with rapid-onset opioids, to multimodal drug combinations, nitrous oxide, regional blocks, or non-pharmacological approaches such as hypnosis and virtual reality. The most reliable way to administer drugs is intravenously. Fast-acting opioids can be combined with ketamine, propofol or benzodiazepines. Adjuvant drugs such as clonidine or NSAIDs and paracetamol (acetaminophen) have also been used. Patients receiving ketamine will usually maintain spontaneous breathing. This is an important feature in patients who are continuously turned during wound dressing procedures and where analgo-sedation is often performed by practitioners who are not specialists in anaesthesiology.Drugs are given in small boluses or by patient-controlled sedation, which is titrated to effect, according to sedation and pain scales. Patient-controlled infusion with propofol has also been used. However, we must bear in mind that burn patients often show an altered pharmacokinetic and pharmacodynamic response to drugs as a result of altered haemodynamics, protein binding and/or increased extracellular fluid volume, and possible changes in glomerular filtration. Because sedation and analgesia can range from minimal sedation (anxiolysis) to general anaesthesia, sedative and analgesic agents should always be administered by designated trained practitioners and not by the person performing the procedure. At least one individual who is capable of establishing a patent airway and positive pressure ventilation, as well as someone who can call for additional assistance, should always be present whenever analgo-sedation is administered.Oxygen should be routinely delivered during sedation. Blood pressure and continuous ECG monitoring should be carried out whenever possible, even if a patient is undergoing bathing or other procedures that may limit monitoring of vital pulse-oximetry parameters.

Helmet Ventilation for Acute Respiratory Failure and Nasal Skin Breakdown in Neuromuscular Disorders

Noninvasive ventilation (NIV) has been widely used to decrease the complications associated with tracheal intubation in mechanically ventilated patients with neuromuscular diseases in acute respiratory failure. However, nasal ulcerations might occur when masks are used as an interface. Helmet ventilation is a possible option in this case. We describe two patients with acute respiratory failure due to Duchenne muscular dystrophy who developed nasal bridge skin necrosis during NIV. Helmet pressure support ventilation caused significant patient-ventilator asynchrony, leading to NIV intolerance. Thus, biphasic positive airway pressure delivered by helmet was applied, which improved gas exchange and patient-ventilator interaction, allowing successful NIV.

Delirium: clinical approach and prevention.

Delirium, defined as an acute fluctuating change in mental state, with consciousness and cognitive impairment, has been found to have a high incidence in hospitalised patients, as well as being associated with increased morbidity and mortality, prolonged stays in the intensive care unit (ICU) and in hospital and higher costs. However, delirium is not easy to detect, since its diagnosis is mainly clinical. Yet the importance of early diagnosis and possible prevention in the different clinical scenarios is clear, to improve patient prognosis. This review provides a practical approach to delirium management through: (a) its classification and diagnosis utilising validated tools and (b) the use of non-pharmacological protocols and of an early prediction model to identify high-risk patients, who are more likely to benefit from pharmacological prophylaxis.

Noninvasive Ventilation in Critically Ill Patients

Since its first application in the late 1980s, noninvasive ventilation (NIV) has been the first-line intervention for certain forms of acute respiratory failure. NIV may be delivered through the patients mouth, nose, or both using noninvasive intermittent positive pressure ventilation or continuous positive airway pressure. When applied appropriately, NIV may reduce morbidity and mortality and may avert iatrogenic complications and infections associated with invasive mechanical ventilation. This article provides physicians and respiratory therapists with a comprehensive, practical guideline for using NIV in critical care.

Different tracheotomy tube diameters influence diaphragmatic effort and indices of weanability in difficult to wean patients.

OBJECTIVE: To determine the effects of different tracheotomy tube sizes on diaphragm effort and weanability indices. METHODS: Ten tracheotomized and difficult to wean subjects were randomized to 2 T-piece trials, with different tracheotomy tube diameters: inner diameters 8 mm and 6.5 mm. Diaphragm pressure-time product per min. (PTPdi/min), lung compliance and resistance (CL and RL), breathing pattern, tension-time index of the diaphragm (TTdi), and the ratio of breathing frequency to tidal volume (f/VT) were recorded. In an in vitro model, the flow-pressure relationship was measured using the 2 tracheotomy tubes and 2 endotracheal tubes of the same diameter. RESULTS: The use of a smaller diameter resulted in an increase of PTPdi (337.63 ± 194.35 cm H2O · s/min vs 263.28 ± 156.23 cm H2O · s/min for 6.5 mm and 8 mm, respectively, P = .004) and RL (16.74 ± 8.10 cm H2O · s/min vs 11.72 ± 7.88 cm H2O · s/min, respectively, P = .008). Both weanability indices were also significantly higher using the smaller tube: f/VT 93.32 ± 20.91 vs 77.06 ± 19.26 for 6.5 mm and 8 mm, respectively, P < .02; TTdi 0.09 ± 0.052 vs 0.08 ± 0.04, respectively, P < .02. In vitro measurements confirmed that the resistances were higher with the smaller diameter and similar between the tracheotomy tubes and the endotracheal tubes of the same diameters. CONCLUSIONS: In tracheotomized difficult to wean subjects the decrease of the tracheotomy tube size was associated with an increased PTPdi, f/VT, and TTdi, that were otherwise normal, using a higher diameter. The in vitro study showed that the resistances increased similarly for tracheotomy tube and endotracheal tube, decreasing the diameter and increasing the flows.