Prognostic value of on admission arterial PCO2 in hospitalized patients with community-acquired pneumonia

Bicarbonate concentration as a predictor of prognosis in moderately severe COVID-19 patients: A multicenter retrospective study

Background

Coronavirus disease 2019 (COVID-19) patients reportedly have high bicarbonate concentration. However, its relationship to the disease progression are obscure.

Methods

In this two-center retrospective study, we included COVID-19 patients with moderate severity between March 2020 and May 2021. We classified patients into three groups according to bicarbonate concentrations: high (>27 mEq/L), normal (21 to 27 mEq/L), and low (<21 mEq/L). The primary outcome was the time to clinical worsening defined by the requirement of intubation or death during 90 days. We evaluated high or low bicarbonate concentration during the clinical course related to the primary outcome using multivariable Cox proportional hazard models.

Results

Of the 60 participants (median age 72 years), 60% were men. Participants were classified into high (13 patients), normal (30 patients), and low (17 patients) groups. Clinical worsening occurred in 54% of patients in the high group, 23% in the normal group, and 65% in the low group. Both high and low groups were associated with a higher clinical worsening rate: HR, 3.02 (95% CI, 1.05 to 8.63) in the high group; 3.49 (95% CI: 1.33 to 9.12) in the low group.

Conclusion

Monitoring of bicarbonate concentrations may be useful to predict the prognosis.

Inappropriate Ventilatory Homeostatic Responses in Hospitalized COVID-19 Patients

Background

The clinical presentation of COVID-19 suggests altered breathing control - tachypnoea, relative lack of dyspnoea, and often a discrepancy between severity of clinical and radiological findings. Few studies characterize and analyse the contribution of breathing drivers and their ventilatory and perceptual responses.

Aim

To establish the prevalence of inappropriate ventilatory and perceptual response in COVID-19, by characterizing the relationships between respiratory rate (RR), dyspnoea and arterial blood gas (ABG) in a cohort of COVID-19 patients at presentation to hospital, and their post-Covid respiratory sequelae at follow-up.

Methods

We conducted a retrospective cohort study including consecutive adult patients admitted to hospital with confirmed COVID-19 between 1st March 2020 and 30th April 2020. In those with concurrent ABG, RR and documented dyspnoea status on presentation, we documented patient characteristics, disease severity, and outcomes at hospital and 6-week post-discharge.

Results

Of 492 admissions, 194 patients met the inclusion criteria. Tachypnoea was present in 75% pronounced (RR>30) in 36%, and persisted during sleep. RR correlated with heart rate (HR) (r = 0.2674), temperature (r = 0.2824), CRP (r = 0.2561), Alveolar-arterial (A-a) gradient (r = 0.4189), and lower PaO₂/FiO₂ (PF) ratio (r = −0.3636). RR was not correlated with any neurological symptoms. Dyspnoea was correlated with RR (r = 0.2932), A-a gradient (r = 0.1723), and lower PF ratio (r = −0.1914), but not correlated with PaO₂ (r = −0.1095), PaCO₂ (r = −0.0598) or any recorded neurological symptom except for altered consciousness. Impaired ventilatory homeostatic control of pH/PaCO₂ [tachypnoea (RR>20), hypocapnia (PaCO₂ <4.6 kPa), and alkalosis (pH>7.45)] was observed in 29%. This group, of which 37% reported no dyspnoea, had more severe respiratory disease (A-a gradient 38.9 vs. 12.4 mmHg; PF ratio 120 vs. 238), and higher prevalence of anosmia (21 vs. 15%), dysgeusia (25 vs. 12%), headache (33 vs. 23%) and nausea (33 vs. 14%) with similar rates of new anxiety/depression (26 vs. 23%), but lower incidence of past neurological or psychiatric diagnoses (5 vs. 21%) compared to appropriate responders. Only 5% had hypoxia sufficiently severe to drive breathing (i.e. PaO₂ <6.6 kPa). At 6 weeks post-discharge, 24% (8/34) showed a new breathing pattern disorder with no other neurological findings, nor previous respiratory, neurological, or psychiatric disorder diagnoses.

Conclusions

Impaired homeostatic control of ventilation i.e., tachypnoea, despite hypocapnia to the point of alkalosis appears prevalent in patients admitted to hospital with COVID-19, a finding typically accompanying more severe disease. Tachypnoea prevalence was between 12 and 29%. Data suggest that excessive tachypnoea is driven by both peripheral and central mechanisms, but not hypoxia. Over a third of patients with impaired homeostatic ventilatory control did not experience dyspnoea despite tachypnoea. A subset of followed-up patients developed post-covid breathing pattern disorder.

Patient functionality and walking speed after discharge from the intensive care unit

Objective

To measure and compare the functionality of patients after discharge from the intensive care unit and at the time of hospital discharge.

Methods

Quantitative study of a prospective cohort performed between August of 2016 and December of 2017 at a university hospital. A 10-meter walk test was performed at 2 timepoints: after discharge from the intensive care unit and prior to hospital discharge. The data were analyzed using Student's t-test and Pearson or Spearman correlation. Statistical Package for Social Science (SPSS) version 21.0 was used for the analysis, and p ≤ 0.05 was adopted as the level of significance.

Results

Forty patients, with a mean age of 57.1 ± 12.2 years and with a predominance of males (60%), were evaluated. For the post-intensive care unit test, a mean speed of 0.48m/s was observed, and for the pre-hospital discharge test, there was an increase to 0.71m/s, evidencing functional evolution during the hospital stay (p < 0.001).

Conclusion

There was significant improvement in walking speed at the time of hospital discharge when compared to the walking speed at the time of intensive care unit discharge.

Association of hypercapnia on admission with increased length of hospital stay and severity in patients admitted with community-acquired pneumonia: a prospective observational study from Pakistan

OBJECTIVE

To determine whether the presence of hypercapnia on admission in adult patients admitted to a university-based hospital in Karachi, Pakistan with community-acquired pneumonia (CAP) correlates with an increased length of hospital stay and severity compared with no hypercapnia on admission.

STUDY DESIGN

A prospective observational study.

SETTINGS

Tertiary care hospital in Karachi, Pakistan.

METHODS

Patients who met the inclusion criteria were enrolled in the study. The severity of pneumonia was assessed by CURB-65 and PSI scores. An arterial blood gas analysis was obtained within 24 hours of admission. Based on arterial PaCO₂ levels, patients were divided into three groups: hypocapnic (PaCO₂ <35 mm Hg), hypercapnic (PaCO₂ >45 mm Hg) and normocapnic (PaCO₂ <35-45 mm Hg).

OUTCOMES

The primary outcome was the association of hypercapnia on admission with mean length of hospital stay. Secondary outcomes were the need for mechanical ventilation, ICU admission and in-hospital mortality.

RESULTS

A total of 295 patients of mean age 60.20±17.0 years (157 (53.22%) men) were enrolled over a 1-year period. Hypocapnia was found in 181 (61.35%) and hypercapnia in 57 (19.32%) patients. Hypercapnic patients had a longer hospital stay (mean 9.27±7.57 days), increased requirement for non-invasive mechanical ventilation (NIMV) on admission (n=45 (78.94%)) and longer mean time to clinical stability (4.39±2.0 days) compared with the other groups. Overall mortality was 41 (13.89%), but there was no statistically significant difference in mortality (p=0.35) and ICU admission (p=0.37) between the three groups. On multivariable analysis, increased length of hospital stay was associated with NIMV use, ICU admission, hypercapnia and normocapnia.

CONCLUSION

Hypercapnia on admission is associated with severity of CAP, longer time to clinical stability, increased length of hospital stay and need for NIMV. It should be considered as an important criterion to label the severity of the illness and also a determinant of patients who will require a higher level of hospital care. However, further validation is required.