Table 1.
Summary of interventions available for the treatment of hypercapnia.
| Intervention | Advantages | Disadvantages |
|---|---|---|
| Increase minute ventilation | Ease to institute at bedside | Potential for barotrauma, volutrauma, worsening dynamic hyperinflation |
| Possible on most ventilators | ||
| Increase end inspiratory pause prolongation | Ease to institute at bedside | Shortens expiratory time, can cause dynamic hyperinflation |
| Possible on most ventilators | ||
| Buffers—sodium bicarbonate and THAM | Sodium bicarbonate—widely available, may improve vasopressor responsiveness | No large body of data to support their use |
| THAM is not widely available and can cause hyperkalaemia, hypoglycaemia and hepatic dysfunction | ||
| Prone position ventilation | Shown to improve mortality in patients with ARDS | Difficult to perform in some patients such morbidly obese, abdominal compartment syndrome, severe haemodynamic instability |
| Can be instituted anywhere | ||
| Reduced shunting | ||
| Experience required in instituting safely | ||
| Proven to reduce mortality | ||
| Early application of prolonged prone-positioning sessions are required to reduce mortality | ||
| Airway pressure release ventilation | Reduction in shunt secondary to alveolar recruitment | Familiarity with the mode of ventilation important for appropriate use |
| Cannot be used in some patients such as those with bronchopleural fistula and increased airway resistance | ||
| Potential for barotrauma | ||
| High frequency oscillation ventilation | Recruitment of collapsed lung tissue | Need for concomitant deep sedation +/− paralysis |
| Minimise volutrauma | Increases right ventricular strain | |
| May not improve or indeed worsen mortality | ||
| Not widely available | ||
| Extracorporeal membrane oxygenation | Can support oxygenation and ventilation. | Invasive. Complexity of circuit. Need for anticoagulation. Not widely available. Mortality benefit is still unclear |
| Can remove all metabolically produced CO2 | ||
| Low flow extracorporeal CO2 removal devices | Minimally invasive, efficient in CO2 removal | Not widely available. Need for anticoagulation. Cannot provide oxygenation or remove all metabolically produced CO2 (partial support) |
THAM: tris-hydroxymethyl aminomethane.