Clinical determinants and prognostic significance of hypocapnia in acute heart failure

Abstract

The aim of this research was to examine the prevalence of hyperventilation (defined by pCO2 value) among acute heart failure (AHF) patients and to link it with potential triggers and prognosis. All patients underwent dyspnea severity assessment and capillary blood examination on hospital admission and during hospitalization. Out of 241 AHF patients, 57(24%) were assigned to low pCO2 group (pCO2 ≤ 30 mmHg) and 184 (76%) to normal pCO2 group (pCO2 > 30 mmHg). Low pCO2 group had significantly lower HCO3- (22.3 ± 3.4 vs 24.7 ± 2.9 mmol/L, p < 0.0001) and significantly higher lactate level (2.53 ± 1.6 vs 2.14 ± 0.97 mmol/L, p = 0.03). No differences between groups were observed in respect to the following potential triggers of hyperventilation: hypoxia (sO2 92.5 ± 5.2 vs 92 ± 5.6% p = 0.57), infection (CRP 10.5[4.9–26.4]vs 7.15[3.45–17.35] mg/L, p = 0.47), dyspnea severity (7.8 ± 2.3vs 8.0 ± 2.3 points, p = 0.59) and pulmonary congestion (82.5 vs 89.1%, p = 0.19), respectively. Low pCO2 value was related to an increased 4-year all-cause mortality hazard ratio (HR) (95% CI) 2.2 (1.3–3.6); p = 0.002 and risk of death and of rehospitalization for HF, HR (95% CI) 2.0 (1.3–3.0); p = 0.002. Hyperventilation is relatively frequent in AHF and is related to poor prognosis. Low pCO2 was not contingent on expected potential triggers of dyspnea but rather on tissue hypoperfusion.

Prognostic significance and clinical determinants of residual dyspnoea at discharge in acute heart failure: a single-centre, prospective observational study

“…Surprisingly, the residual dyspnoea was neither related to markers of neurohormonal activation (renin/aldosterone) nor to iron metabolism biomarkers (Fe, TSAT, sTfR). Each AHF episode is related to multiorgan dysfunction, and that peripheral hypoperfusion, may potentially trigger the dyspnoea, but this was not a cause in the population either 22–24. Finally, the patients who reported persistent dyspnoea had the same pO 2 , O 2 saturation and pCO 2 as those without the dyspnoea, which supports the concept that desaturation is not a major driver of dyspnoea in HF.…”

A Novel Nomogram for Predicting the Risk of Acute Heart Failure in ICU Patients with COPD

“…Patients with AHF combined with COPD often experience ventilation. Low pCO2 is an important manifestation of hyperventilation and is closely associated with poor prognosis in AHF patients [31,32]. Our nomogram shows a decrease in pCO2 after AHF in COPD patients, which suggests that clinicians should be more cautious when deciding on ventilation therapy.…”

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

“…A cohort study by Kato et al [14] in Japan found that in AHF patients admitted to the cardiac care unit, the lower the PaCO 2 at admission, the higher the long-term mortality risk. In addition, Garus et al [15] demonstrated that low PaCO 2 correlated with an increased 1-year death rate in AHF patients. The ndings of our study were homologous with the results of these two studies, but the sample size was larger.…”

“…Several research studies have suggested that hypocapnia is connected with increased mortality in patients with AHF. 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].…”