A strange case of severe but fleeting hypoxemia in patient with COVID-19 infection: maybe virus-induced pulmonary Raynaud's phenomenon?

This case-report describes severe acute respiratory failure in a patient with a COVID-19 positive nasopharyngeal swab that spontaneously resolved within a few hours. It is speculated that the virus may have caused a fleeting pulmonary vasospasm.

Passive Versus Active Circuit During Invasive Mechanical Ventilation in Subjects With Amyotrophic Lateral Sclerosis.

BACKGROUND: Until recently, it has been considered essential to maintain the use of a double-limb circuit in patients with amyotrophic lateral sclerosis (ALS) to avoid rebreathing expired air during invasive mechanical ventilation. Currently, life-sustaining home ventilators can work with a single, lighter circuit that is easier to manage. Our aim was to evaluate the effectiveness and safety of a single-limb circuit with intentional leaks (passive circuit) in comparison with a circuit with an expiratory valve (active circuit), in subjects with ALS who use invasive home ventilation. METHODS: We conducted a retrospective single-center study. The enrolled subjects were divided into 2 groups according to the type of exhalation port. The aim of the study was to compare arterial blood gases; nocturnal oxygen saturation recordings; and the occurrence of adverse events, both clinical and technical events. In addition, we compared the rate of mortality and unplanned hospital admissions that occurred within a year after discharge from the hospital. RESULTS: Forty-three subjects were included in our study: 23 who used a passive circuit and 20 who used an active circuit. No significant difference in nocturnal and diurnal gas exchanges was detected. The incidence of adverse events was significantly higher in the active circuit group (85% in active circuit vs 30% in passive circuit, P < .001). However, by splitting the adverse events into 2 categories, clinical and technical, the technical events were significantly more frequent in the active circuit group. None of these events led to hospital admission or death. CONCLUSIONS: The passive circuit was shown to be as effective and safe as the active circuit during home invasive ventilation in the subjects with amyotrophic lateral sclerosis. A future randomized controlled study is necessary to confirm these results and to extend indications to other pathologies.

Physiological response to intrapulmonary percussive ventilation in stable COPD patients.

Intrapulmonary percussive ventilation (IPV) is a ventilatory technique that delivers bursts of high-flow respiratory gas into the lung at high rates, intended for treating acute respiratory failure and for mobilization of secretions. We performed a study, aimed at assessing the physiological response to IPV, on patients' breathing pattern, inspiratory effort, lung mechanics and tolerance to ventilation. Ten COPD patients underwent randomized trials of IPV through a face mask at different pressure/frequency combinations (1.2 bar/250 cycles/min; 1.8/250; 1.2/350; 1.8/350), separated by return to baseline (SB), using the IMP2 ventilator. In 5 patients we have also compared the physiological changes of IPV with those obtained during pressure support ventilation (PSV). Minute ventilation did not vary among the trials, but tidal volumes (VT) were significantly greater during 1.2/250, 1.2/350 and 1.8/350 compared to SB. The pressure time product of the diaphragm per minute (PTPdi/min) estimate of the diaphragm oxygen expenditure was also significantly reduced during 1.2/250 and 1.8/250 (209 cmH2O x s/min for SB vs. 143 and 125 for 1.2/250 and 1.8/250, respectively P < 0.05), as well as dynamic intrinsic end-expiratory pressure (PEEPi,dyn). Similar reduction in PTPdi/min were obtained also during PSV. Tolerance to ventilation and oxygen saturation were satisfactory and did not change during the different trials. In 5 normal subjects a prolonged apnea trial lasting > 2 min was also performed, without any significant decrease in SaO2 or subjective discomfort. In conclusion, IPV was able to guarantee an adequate ventilation, while inducing a significant unloading of the diaphragm during the "low-frequency" trials.