Clinical review: Helmet and non-invasive mechanical ventilation in critically ill patients.
Bottom Line: In eight studies oxygenation was similar in the two groups, while the intubation rate was similar in four and lower in three studies for the helmet group compared to face mask group.The outcome was similar in six studies.The tolerance was better with the helmet in six of the studies.
Non-invasive mechanical ventilation (NIV) has proved to be an excellent technique in selected critically ill patients with different forms of acute respiratory failure. However, NIV can fail on account of the severity of the disease and technical problems, particularly at the interface. The helmet could be an alternative interface compared to face mask to improve NIV success. We performed a clinical review to investigate the main physiological and clinical studies assessing the efficacy and related issues of NIV delivered with a helmet. A computerized search strategy of MEDLINE/PubMed (January 2000 to May 2012) and EMBASE (January 2000 to May 2012) was conducted limiting the search to retrospective, prospective, nonrandomized and randomized trials. We analyzed 152 studies from which 33 were selected, 12 physiological and 21 clinical (879 patients). The physiological studies showed that NIV with helmet could predispose to CO₂ rebreathing and increase the patients' ventilator asynchrony. The main indications for NIV were acute cardiogenic pulmonary edema, hypoxemic acute respiratory failure (community-acquired pneumonia, postoperative and immunocompromised patients) and hypercapnic acute respiratory failure. In 9 of the 21 studies the helmet was compared to a face mask during either continous positive airway pressure or pressure support ventilation. In eight studies oxygenation was similar in the two groups, while the intubation rate was similar in four and lower in three studies for the helmet group compared to face mask group. The outcome was similar in six studies. The tolerance was better with the helmet in six of the studies. Although these data are limited, NIV delivered by helmet could be a safe alternative to the face mask in patients with acute respiratory failure.
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Mentions: The standard treatment for acute respiratory failure in critically ill patients has been based on oxygen therapy and invasive mechanical ventilation with endotracheal intubation. In addition, non-invasive mechanical ventilation (NIV) has proved an excellent technique, avoiding the need for intubation and improving outcome in selected patients with acute cardiogenic pulmonary edema, exacerbation of chronic obstructive pulmonary disease (COPD), and acute hypoxemic respiratory failure [1-4]. Conversely to invasive mechanical ventilation, NIV can also be used outside the intensive care unit . However, NIV can fail because of either the patient's underlying conditions or multiple technical causes. Despite improvements in the oro-nasal mask's characteristics, intolerance to the device represents a frequent cause of failure ; thus, the interface is fundamental in the care of patients. One possible alternative to the face mask could be the helmet, especially for long-term use (Figure 1). Although the facial mask is still the most commonly used interface in up to 60% of cases, in some European countries (such as Italy), the helmet is widely employed for patients with acute hypoxemic respiratory failure and acute cardiogenic pulmonary edema .