Oxygen consumption and PEEPe in ventilated COPD patients

Effect of pressures and type of ventilation on aerosol delivery to chronic obstructive pulmonary disease patients

Background

Continuous Positive Airway Pressure (CPAP), BiPhasic Positive Airway Pressure (BiPAP), and high flow nasal cannula (HFNC) show some evidence to have efficacy in COVID-19 patients. Delivery during noninvasive mechanical ventilation (NIV) or HFNC gives faster and more enhanced clinical effects than when aerosols are given without assisted breath. The present work aimed to compare the effect of BiPhasic Positive Airway Pressure (BiPAP) mode at two different pressures; low BiPAP (Inspiratory Positive Airway Pressure (IPAP)/Expiratory Positive Airway Pressure (EPAP) of 10/5 cm water) and high BiPAP (IPAP/EPAP of 20/5 cm water), with HFNC system on pulmonary and systemic drug delivery of salbutamol. On the first day of the experiment, all patients received 2500 μg salbutamol using Aerogen Solo vibrating mesh nebulizer. Urine samples 30 min post-dose and cumulative urinary salbutamol during the next 24 h were collected on the next day. On the third day, the ex-vivo filter was inserted before the patient to collect the delivered dose to the patient of the 2500 μg salbutamol. Salbutamol was quantified using high-performance liquid chromatography (HPLC).

Results

Low-pressure BiPAP showed the highest amount delivered to the lung after 30 min followed by HFNC then high-pressure BiPAP. But the significant difference was only observed between low and high-pressure BiPAP modes (p = 0.012). Low-pressure BiPAP showed the highest delivered systemic delivery amount followed by HFNC then high-pressure BiPAP. Low-pressure BiPAP was significantly higher than HFNC (p = 0.017) and high-pressure BiPAP (p = 0.008). No significant difference was reported between HFNC and high-pressure BiPAP. The ex-vivo filter was the greatest in the case of low-pressure BiPAP followed by HFNC then high-pressure BiPAP. Low-pressure BiPAP was significantly higher than HFNC (p = 0.033) and high-pressure BiPAP (p = 0.008). Also, no significant difference was found between HFNC and high-pressure BiPAP.

Conclusions

Our results of pulmonary, systemic, and ex-vivo drug delivery were found to be consistent. The low BiPAP delivered the highest amount followed by the HFNC then the high BiPAP with the least amount. However, no significant difference was found between HFNC and high BiPAP.

Does using pressure-controlled ventilation to rest respiratory muscles improve sleep in ICU patients?

PURPOSE

Sleep is commonly altered in critically ill patients. Ventilatory mode may impact on quality of sleep. The aim of our study was to evaluate the effect on sleep of pressure-controlled ventilation (PCV) to spontaneous ventilation with 6 cm H2O inspiratory pressure (low-PSV).

METHODS

Thirty-five patients intubated and mechanically ventilated for acute-on-chronic respiratory failure were included in this prospective randomized cross-over study. Nine were discarded, 13 received PCV first (10 p.m.-2 a.m.) and then low-PSV (2-6 a.m.) and 13 patients received low-PSV first and then PCV.

RESULTS

Sleep architecture was altered (50.4% of the night was spent in wakefulness). PCV was associated with significantly improved sleep quality and quantity compared to low-PSV: sleep efficiency (total sleep time/total recording time) was 63% (range: 9-100) vs. 37% (0-96; p = 0.0002), stage 2 NREM sleep was 33% vs. 13% (p = 0.0005), stages 3 and 4 NREM sleep were 9% vs. 3.5% (p = 0.003) and REM sleep was 6.5% vs. 0% (p = 0.003).

CONCLUSIONS

Sleep quantity and quality were significantly improved with PCV compared to low-PSV. Nocturnal respiratory muscles rest through PCV is recommended to improve sleep in ICU patients with acute-on-chronic respiratory failure.

Assist-control ventilation vs. low levels of pressure support ventilation on sleep quality in intubated ICU patients

OBJECTIVE

To compare the impact of assist-control ventilation (ACV) and pressure support ventilation with 6 cmH2O inspiratory pressure (low PSV) on sleep quality.

DESIGN

Prospective randomized cross-over study.

PATIENTS

Twenty intubated and mechanically ventilated patients for acute on chronic respiratory failure.

MEASUREMENTS

Patients were monitored by standard polysomnography at the end of their weaning period. Patients were assigned to receive either ACV from 10 p.m. to 2 a.m. and low PSV from 2 a.m. to 6 a.m. (ACV/low PSV group) or low PSV from 10 p.m. to 2 a.m. and ACV from 2 a.m. to 6 a.m. (low PSV/ACV group).

RESULTS

There were significant increases in stages 1 and 2 non-rapid eye movement (NREM) sleep and reduction in wakefulness during the first part of the night and significant increases in stages 3 and 4 NREM sleep during the second part of the night were observed with ACV compared to low PSV. A significant negative correlation was observed between the perceived sleep quality and the amount of wakefulness while the amount of stage 2 NREM sleep was positively correlated with perceived sleep quality.

CONCLUSIONS

ACV was significantly associated with a better sleep quality than those recorded during pressure support. The perception of sleep quality appeared to be better with ACV than with low PSV. On the basis of these results we recommend that intubated and mechanically ventilated patients for acute on chronic respiratory failure should be reventilated at night during their weaning period.

[Bronchial obstruction in intensive care]

Bronchial obstruction due to one of the major pulmonary diseases asthma, COPD, or emphysema are a common problem in intensive care medicine as the leading cause or as comorbidity. While in pharmacological therapy no major changes have occurred during the last few years, two major advances have been reached in ventilation therapy which are in the focus of this review. First the non invasive ventilation (NIV) has been shown to prove efficient in treating acute on chronic respiratory failure in COPD patients and is capable of shortening the duration of hospital stay. In addition NIV can be used successfully in weaning after long time ventilator therapy and improve prognosis in COPD patients. Secondly the strategy of invasive ventilation therapy has changed significantly. "Permissive hypercapnia" is unequivocally established in severe bronchial obstruction in situations of limited ventilation. When intrinsic PEEP and elevated airway resistance are present PEEP may be useful and the upper limit of airways peak pressure that we are used to in "protective ventilation" of ARDS patients can be necessary and useful to exceed.