Removal of a catheter mount and heat-and-moisture exchanger improves hypercapnia in patients with acute respiratory distress syndrome

Abstract

To avoid ventilator-associated lung injury in acute respiratory distress syndrome (ARDS) treatment, respiratory management should be performed at a low tidal volume of 6 to 8 mL/kg and plateau pressure of ≤30 cmH 2 O. However, such lung-protective ventilation often results in hypercapnia, which is a risk factor for poor outcomes. The purpose of this study was to retrospectively evaluate the effectiveness and safety of the removal of a catheter mount (CM) and using heated humidifiers (HH) instead of a heat-and-moisture exchanger (HME) for reducing the mechanical dead space created by the CM and HME, which may improve hypercapnia in patients with ARDS. This retrospective observational study included adult patients with ARDS, who developed hypercapnia (PaCO 2 > 45 mm Hg) during mechanical ventilation, with target tidal volumes between 6 and 8 mL/kg and a plateau pressure of ≤30 cmH 2 O, and underwent stepwise removal of CM and HME (replaced with HH). The PaCO 2 values were measured at 3 points: ventilator circuit with CM and HME (CM + HME) use, with HME (HME), and with HH (HH), and the overall number of accidental extubations was evaluated. Ventilator values (tidal volume, respiratory rate, minutes volume) were evaluated at the same points. A total of 21 patients with mild-to-moderate ARDS who were treated under deep sedation were included. The values of PaCO 2 at HME (52.7 ± 7.4 mm Hg, P < .0001) and HH (46.3 ± 6.8 mm Hg, P < .0001) were significantly lower than those at CM + HME (55.9 ± 7.9 mm Hg). Measured ventilator values were similar at CM + HME, HME, and HH. There were no cases of reintubation due to accidental extubation after the removal of CM. The removal of CM and HME reduced PaCO 2 values without changing the ventilator settings in deeply sedated patients with mild-to-moderate ARDS on lung-protective ventilation. Caution should be exercised, as the removal of a CM may result in circuit disconnection or accidental extubation. Nevertheless, this intervention may improve hypercapnia and promote lung-protective ventilation.

The role of acute hypercapnia on mortality and short-term physiology in patients mechanically ventilated for ARDS: a systematic review and meta-analysis

“…Definition of hypercapnia and V T used among the included studies have been captured in Table 1 . A clear threshold for hypercapnia was reported in 11/29 of the included studies, that was defined as PaCO 2 ≥ 38 mmHg [ 19 ], PaCO 2 ≥ 45 mmHg [ 11 , 25 , 41 ], ≥ 48 mmHg [ 23 ], ≥ 50 mmHg [ 5 , 28 , 33 , 35 , 44 ] or ≥ 55 mmHg[ 34 ]. Information regarding V T were reported in all but three studies [ 5 , 26 , 27 ].…”

The Role of Pyroptosis and Autophagy in the Nervous System

“…The typical symptom of acute respiratory distress syndrome (ARDS) is persistent hypoxemia, which often requires ventilation to correct hypoxemia. The ventilatory strategies can lead to hypercapnia [ 43 , 44 ]. It has been reported that in hypoxic adult rats, hypercapnia can induce IL-1β overproduction by activating nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome [ 45 , 46 ].…”