Association between prehospital arterial hypercapnia and mortality in acute heart failure: a retrospective cohort study

Abstract

Background Acute Heart Failure (AHF) is a potentially lethal pathology and is often encountered in the prehospital setting. Although an association between prehospital arterial hypercapnia in AHF patients and admission in high-dependency and intensive care units has been previously described, there is little data to support an association between prehospital arterial hypercapnia and mortality in this population. Methods This was a retrospective study based on electronically recorded prehospital medical files. All adult patients with AHF were included. Records lacking arterial blood gas data were excluded. Other exclusion criteria included the presence of a potentially confounding diagnosis, prehospital cardiac arrest, and inter-hospital transfers. Hypercapnia was defined as a PaCO2 higher than 6.0 kPa. The primary outcome was in-hospital mortality, and secondary outcomes were 7-day mortality and emergency room length of stay (ER LOS). Univariable and multivariable logistic regression models were used. Results We included 225 patients in the analysis. Prehospital hypercapnia was found in 132 (58.7%) patients. In-hospital mortality was higher in patients with hypercapnia (17.4% [23/132] versus 6.5% [6/93], p = 0.016), with a crude odds-ratio of 3.06 (95%CI 1.19–7.85). After adjustment for pre-specified covariates, the adjusted OR was 3.18 (95%CI 1.22–8.26). The overall 7-day mortality was also higher in hypercapnic patients (13.6% versus 5.5%, p = 0.044), and ER LOS was shorter in this population (5.6 h versus 7.1 h, p = 0.018). Conclusion Prehospital hypercapnia is associated with an increase in in-hospital and 7-day mortality in patient with AHF.

Hypocapnia is an independent predictor of in‐hospital mortality in acute heart failure

“…Clinically, hypercapnia indicates an airway obstruction and, if accompanied by hypoxaemia, is considered an indicator of respiratory failure requiring mechanical ventilation for patients with pulmonary oedema 23 . AHF patients with hypercapnia have poorer vital signs and are at a greater risk of in‐hospital mortality compared with those without hypercapnia 8,24 . Interestingly, a potential association has been found between hypocapnia and poor prognosis in patients treated with mechanical ventilation, such as those with traumatic brain injury or acute respiratory distress syndrome 25,26 .…”

“…23 AHF patients with hypercapnia have poorer vital signs and are at a greater risk of in-hospital mortality compared with those without hypercapnia. 8,24 Interestingly, a potential association has been found between hypocapnia and poor prognosis in patients treated with mechanical ventilation, such as those with traumatic brain injury or acute respiratory distress syndrome. 25,26 In addition, Carrillo-Aleman et al 27 noted that a 2 < 35 mmHg was associated with worse outcomes in patients with cardiogenic pulmonary oedema who were mechanically ventilated on admission.…”

“…Hypercapnia, which is determined by partial pressure of arterial carbon dioxide (PaCO 2 ) > 45 mmHg, is a hallmark of respiratory failure and is associated with poor prognosis in a variety of diseases, including AHF. [8][9][10] Interestingly, in several recent studies, hypocapnia (PaCO 2 < 35 mmHg) was significantly correlated with the mortality of patients after cardiac arrest. 11 This condition was also linked to poor prognosis in patients with traumatic brain injury and communityacquired pneumonia.…”

“…Pulmonary impairments can present as respiratory failure through pulmonary congestion. Hypercapnia, which is determined by partial pressure of arterial carbon dioxide (PaCO 2 ) > 45 mmHg, is a hallmark of respiratory failure and is associated with poor prognosis in a variety of diseases, including AHF 8–10 . Interestingly, in several recent studies, hypocapnia (PaCO 2 < 35 mmHg) was significantly correlated with the mortality of patients after cardiac arrest 11 .…”

Prognostic effects of arterial partial pressure of carbon dioxide in critical patients with acute heart failure: a retrospective cohort study

“…However, these studies [14,15] mainly focused on medium-and long-term mortality, and their sample sizes were small. Additionally, the correlation between hypercapnia and mortality in AHF patients remains controversial [16][17][18]. Therefore, in the present research study, we analyzed data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database V2.0, to determine if there is a relationship between the baseline arterial partial pressure of carbon dioxide (PaCO 2 ) and the short-term outcomes of the critical AHF population.…”