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To investigate the efficacy and safety of non-invasive ventilation (NIV) with high PEEP levels application in patients with COVID–19–related acute respiratory distress syndrome (ARDS).
Methods:
This is a retrospective cohort study with data collected from 95 patients who were administered NIV as part of their treatment in the COVID-19 intensive care unit (ICU) at University Hospital Centre Zagreb between October 2021 and February 2022. The definite outcome was NIV failure.
Results:
High PEEP NIV was applied in all 95 patients; 54 (56.84%) patients could be kept solely on NIV, while 41 (43.16%) patients required intubation. ICU mortality of patients solely on NIV was 3.70%, while total ICU mortality was 35.79%. The most significant difference in the dynamic of respiratory parameters between 2 patient groups was visible on Day 3 of ICU stay: By that day, patients kept solely on NIV required significantly lower PEEP levels and had better improvement in PaO2, P/F ratio, and HACOR score.
Conclusion:
High PEEP applied by NIV was a safe option for the initial respiratory treatment of all patients, despite the severity of ARDS. For some patients, it was also shown to be the only necessary form of oxygen supplementation.
Hypoxia is a frequently reported complication during the intubation procedure in the emergency department (ED) and may cause bad outcomes. Therefore, oxygenation plays an important role in emergency airway management. The efficacy of oxygenation with high-flow nasal cannula (HFNC) in the ED has been studied, though the evidence is limited. The study aim was to compare two methods of preoxygenation in patients undergoing rapid sequence intubation (RSI) in the ED: (1) HFNC and (2) bag-valve mask (BVM) oxygenation.
Methods:
This is a single-center, prospective, randomized controlled trial (RCT) in adult ED patients requiring RSI. Patients were randomized to receive preoxygenation with either HFNC or BVM. While HFNC therapy was continued during the intubation procedure, BVM oxygenation was interrupted for laryngoscopy. The primary outcome was the lowest peripheral oxygen saturation (SpO2) level during intubation. Secondary outcomes were incidence of desaturation (SpO2<90%) and severe hypoxemia (SpO2<80%) throughout the procedure, intubation time, rate of failed intubation, and 30-day survival rates.
Results:
A total of 135 patients were randomized into two groups (HFNC n = 68; BVM n = 67). The median lowest SpO2 value measured during intubation was 96% (88.8%-99.0%) in the HFNC group and 92% (86.0%-97.5%) in the BVM group (P = .161). During the intubation procedure, severe hypoxemia occurred in 13.2% (n = 9) of patients in the HFNC group and 8.9% (n = 6) in the BVM group, while mild hypoxemia was observed in 35.8% (n = 24) of the BVM group and 26.5% (n = 18) of the HFNC group. However, there was no statistically significant difference between the groups in terms of hypoxemia development (P = .429 and P = .241, respectively). No significant difference was reported in the rate of failed intubation between the groups. Thirty-day mortality was observed in 73.1% of the BVM group and 57.4% of the HFNC group, with a borderline statistically significant difference (difference 15.7; 95% CI of the difference: −0.4 to 30.7; P = .054).
Conclusion:
The use of HFNC for preoxygenation, when compared to standard care with BVM oxygenation, did not improve the lowest SpO2 levels during intubation. Also, the use of HFNC during intubation did not provide benefits in reducing the incidence of severe hypoxemia. However, the 30-day survival rates were slightly better in the HFNC group compared to the BVM group.
This chapter discusses the diagnosis, evaluation and management of chronic obstructive pulmonary disease (COPD). Airflow restriction may be severe, leading to patients presenting in an upright or tripod position, with cyanosis, altered mental status, and respiratory arrest. Patients should be placed on supplemental oxygen therapy as needed to maintain adequate oxygen saturations of 88-92%. Over-oxygenating the COPD patient can lead to worsening ventilation-perfusion mismatch and apnea. Patients must be monitored for signs of impending respiratory failure. CPAP and BiPAP may be considered for certain patients with moderate to severe COPD exacerbations. The goal of ventilator management in the COPD patient is to oxygenate and ventilate without causing barotrauma and hemodynamic instability. If patients acutely decompensate while receiving invasive or noninvasive positive pressure ventilation, the possibility of pneumothorax and intrinsic positive end-expiratory pressure (auto-PEEP) should be considered.
This chapter deals with issues related to mechanical ventilation in general and considers those relevant to the obstetric patient in particular. The most common modes of mechanical ventilation are: volume-controlled continuous mandatory ventilation (VC-CMV), pressure-controlled continuous mandatory ventilation (PC-CMV), intermittent mandatory ventilation (IMV), continuous mandatory ventilation (CMV), airway pressure release ventilation (APRV) and positive end-expiratory pressure (PEEP). All patients receiving mechanical ventilation should be monitored by pulse oximetry. Non-invasive ventilation can be delivered nasally or by face mask, using either a conventional mechanical ventilator or a machine designed specifically for this purpose. The 2009 H1N1 influenza pandemic and the particular susceptibility of pregnancy in such circumstances reinforce the need to appraise the rationale for mechanical ventilation in such patients. Finally, APRV as a ventilatory paradigm, in particular, may be particularly useful in the pregnant patient with pneumonits, acute lung injury, or acute respiratory distress syndrome (ARDS).
Volumetric capnography (VC) provides valuable insights into lung collapse-recruitment physiology in a noninvasive and real-time manner, and thus lends itself to monitoring cyclic recruitment maneuvers at the bedside. Lung recruitment is a pressure-dependent phenomenon. Positive end-expiratory pressure (PEEP) needed to prevent the lung from recollapse after the recruitment maneuver is higher in patients with pulmonary diseases. Lung recruitment improves CO2 elimination by increasing the area of the alveolar-capillary membrane available for gas exchange. Lung recruitment affects the last two processes, mainly as a consequence of opening previously collapsed pulmonary capillaries and alveoli. Data from VC during lung recruitment can be grouped and analyzed in four principal ways according to CO2 kinetics: lung perfusion; gas exchange; lung ventilation; and gas transport within the airways. The sensitivity and specificity of non-invasive VC can be enhanced by supplemental invasive measurements of gas exchange.
This chapter highlights the role of capnography as a monitoring tool with the different adjuncts to mechanical ventilation that are currently used in critically ill patients. The application of positive end-expiratory pressure (PEEP) is used to increase lung volume and improve oxygenation in patients with acute lung injury (ALI). Studies of unilateral lung injury demonstrate that the consolidated lung regions do not expand to total lung capacity during inflation. Tracheal gas insufflation (TGI) is an adjunct to mechanical ventilation that allows ventilation with small tidal volumes while CO2 is satisfactorily eliminated. High-frequency ventilation (HFV) techniques have three essential elements in common: a high-pressure flow generator, a valve for flow interruption, and a circuit for connection to the patient. Measurement of deadspace fraction early in the course of acute respiratory failure may provide clinicians important physiologic and prognostic information.
Carbon dioxide is excreted by the lungs. Carbon dioxide production is based on metabolic rate and the substrates that are being utilized to drive the Kreb's cycle. Factors that influence pulmonary elimination of carbon dioxide include the volume of dead space, tidal volume, respiratory frequency and positive end-expiratory pressure (PEEP). The balance between arterial and venous carbon dioxide is based upon cardiac output. Hypocapnia can be controlled relatively through adjustment of ventilator settings to reduce minute ventilation in the sedated patient. The effects of hypercapnia and the associated acidaemia may be mitigated through the use of buffering agents. Traditionally, extracorporeal gas exchange (ECGE) has been utilized in patients only as a rescue therapy. In practice, clinicians adopt a technique somewhere between optimal carbon dioxide clearance and more liberal clearance targets, based on assessment of the severity of lung disease and the risks and benefits of ventilatory manipulations or associated interventions.
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