Management of hypercapnia in critically ill mechanically ventilated patients—A narrative review of literature

Abstract

The use of lower tidal volume ventilation was shown to improve survival in mechanically ventilated patients with acute lung injury. In some patients this strategy may cause hypercapnic acidosis. A significant body of recent clinical data suggest that hypercapnic acidosis is associated with adverse clinical outcomes including increased hospital mortality. We aimed to review the available treatment options that may be used to manage acute hypercapnic acidosis that may be seen with low tidal volume ventilation. The databases of MEDLINE and EMBASE were searched. Studies including animals or tissues were excluded. We also searched bibliographic references of relevant studies, irrespective of study design with the intention of finding relevant studies to be included in this review. The possible options to treat hypercapnia included optimising the use of low tidal volume mechanical ventilation to enhance carbon dioxide elimination. These include techniques to reduce dead space ventilation, and physiological dead space, use of buffers, airway pressure release ventilation and prone positon ventilation. In patients where hypercapnic acidosis could not be managed with lung protective mechanical ventilation, extracorporeal techniques may be used. Newer, minimally invasive low volume venovenous extracorporeal devices are currently being investigated for managing hypercapnia associated with low and ultra-low volume mechanical ventilation.

Inclusion of airway pressure release ventilation in the management of respiratory failure and refractory hypercapnia in a dog

“…This is consistent with findings in human medicine that APRV reduces dead space ventilation by placing the patient on the steep portion of the pressure-volume respiratory system compliance curve and by maintaining and enhancing alveolar recruitment through redistribution of gases. 8,9,25 This report described a dog with NCPE and refractory hypercapnia successfully managed with APRV. Little information is present in the veterinary literature regarding the use of APRV, but this mode of ventilation may represent a novel management strategy for refractory hypoxemia or hypercapnia.…”

“…7 Strategies for management of refractory hypercapnia include increasing minute ventilation (by increasing respiratory rate or tidal volume), reducing dead space ventilation, buffer administration, prone positioning, extracorporeal membrane oxygenation, and potentially the use of APRV. 8 APRV settings differ from those found in conventional ventilation.…”

“…This “open lung concept” was developed based on modeling from Mead et al that demonstrated that application of a transpulmonary pressure of 30 cm H 2 O to a heterogeneous lung could cause local pressures exceeding 140 cm H 2 O 7 . Strategies for management of refractory hypercapnia include increasing minute ventilation (by increasing respiratory rate or tidal volume), reducing dead space ventilation, buffer administration, prone positioning, extracorporeal membrane oxygenation, and potentially the use of APRV 8 …”

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

“…The relief of hypercapnia may improve patient prognosis independently and by reducing the tidal volume, driving pressure values, and respiratory rate. Following the report of a negative impact of hypercapnia on the prognosis of patients with ARDS, the removal of the mechanical dead space was recommended in recent reviews and guidelines [ 28 , 29 ] ; however, it may still be an intervention that is not commonly implemented. The removal of CM in addition to HME is another straightforward procedure that may safely and effectively improve hypercapnia in deeply sedated ARDS patients without increasing the risk of accidental extubation.…”

A Case of the Use of Extracorporeal Carbon Dioxide Removal in a Patient With COVID-19 Acute Respiratory Distress Syndrome

“…Outcomes of patients requiring life support and invasive mechanical ventilation remain poor, with some studies estimating over 40% of patients who require invasive mechanical ventilation die in the hospital [ 1 ]. In mechanically ventilated patients, outcomes appear to improve when low tidal volumes, as well as pressures, are used [ 2 ], however, this has been shown to increase the risk of hypercapnia and hypercapnic acidosis [ 3 ]. Extracorporeal CO2 removal (ECCO2R) technology removes CO2 from the patient’s blood using a hollow filter cartridge and thus can be used to manage hypercapnia and resultant acidosis [ 4 - 5 ].…”