Diastolic blood pressure and the risk of primary cardiac arrest among pharmacologically treated hypertensive patients

Hypotension and a positive fluid balance are associated with delirium in patients with shock

The pathogenesis of delirium in critically ill patients is multifactorial. How hypotension and hypoxemia affect brain function and whether they can promote delirium remains unclear. A high cumulative positive fluid balance may also have a negative effect on brain function and promote delirium. We hypothesized that delirium would be more likely to develop in patients with low systemic arterial pressure, hypoxemia and a higher positive fluid balance, and investigated these associations in a prospective observational cohort study in patients with shock. After initial resuscitation, episodes of hypotension, defined as a mean arterial pressure (MAP) <65 mmHg or diastolic pressure <60 mmHg, and hypoxemia, defined as peripheral oxygen saturation (SpO2) <90% for more than one minute or any arterial oxygen concentration (PaO2) <90 mmHg, were recorded during the first 5 days of the ICU stay. Fluid balance was evaluated daily and the 5-day cumulative fluid balance recorded. Delirium was assessed using the Confusion Assessment Method for the ICU. A total of 252 patients were admitted with shock during the study period; 185 (73%) developed delirium. Patients who developed delirium also had more episodes of hypotension with a low MAP (p = 0.013) or diastolic pressure (p = 0.018) during the first five days of the ICU stay than those who did not. Patients with a higher cumulative fluid balance during the same period were also more likely to develop delirium (p = 0.01); there was no significant difference in the occurrence of hypoxemia between groups. Joint modeling, combining a linear-mixed model and an adjusted Cox survival model showed that low diastolic pressure (alpha effect = -0.058±0.0013, p = 0.043) and a positive cumulative fluid balance (alpha effect = 0.04±0.003, p = 0.021) were independently associated with delirium. In conclusion, low diastolic pressure and a cumulative positive fluid balance but not hypoxemia were independently associated with development of delirium in patients with shock.

Relation of Diastolic Blood Pressure and Coronary Artery Calcium to Coronary Events and Outcomes (From the Multi-Ethnic Study of Atherosclerosis)

Diastolic blood pressure has a J-curve relation with coronary heart disease and death. Because this association is thought to reflect reduced coronary perfusion at low diastolic blood pressure, we hypothesized that the J-curve would be most pronounced in persons with coronary artery calcium. In 6,811 participants from the Multi-Ethnic Study of Atherosclerosis, we used Cox models to examine if diastolic blood pressure category is associated with coronary heart disease events, stroke, and mortality. Analyses were conducted in the sample overall and after stratification by coronary artery calcium score. In multivariable-adjusted analyses, compared with diastolic blood pressure of 80 to 89 mm Hg (reference), persons with diastolic blood pressure <60 mm Hg had increased risk of coronary heart disease events (hazard ratio 1.69 [95% confidence interval 1.02 to 2.79]) and all-cause mortality (hazard ratio 1.48 [95% confidence interval 1.10 to 2.00]), but not stroke. After stratification, associations of diastolic blood pressure <60 mm Hg with events were present only in participants with coronary artery calcium >0. Diastolic blood pressure <60 mm Hg was not associated with events when coronary artery calcium was zero. However, the association between diastolic blood pressure and events did not demonstrate statistical interaction when stratified by presence or absence of coronary calcium. We also found no interaction in the association between low diastolic blood pressure and events based on race. In conclusion, diastolic blood pressure <60 mm Hg was associated with increased risk of coronary heart disease events and all-cause mortality in the sample overall, but this association appeared strongest in individuals with subclinical atherosclerosis.

Fuzzy risk stratification and risk assessment model for clinical monitoring in the ICU

BACKGROUND

The decisions that clinicians make in intensive care units (ICUs) based on monitored parameters reflecting physiological deterioration are of major medical and biomedical engineering interest. These parameters have been investigated and assessed for their usefulness in risk assessment.

METHODS

Totally, 127 ICU adult patients were studied. They were selected from a MIMIC II Waveform Database Matched Subset and had continuous monitoring of heart rate, invasive blood pressure, and oxygen saturation. The monitored data were dimension reduced using deep learning autoencoders and then used to train a support vector machine model (SVM). A combination of methods including fuzzy c-means clustering (FCM), and a random forest (RF) was used to determine the risk levels.

RESULTS

When classifying patients into stable or deteriorating groups the main performance parameter was the receiver operating characteristics (ROC). The area under the ROC (AUROC) was 93.2 (95% CI (92.9-93.4)) with sensitivity and specificity values of 0.80 and 0.89, respectively. The suggested fuzzy risk levels using the combined method of the FCM clustering and RF achieved an accuracy of 1 (0.9999, 1), with both sensitivity and specificity values equal to 1.

CONCLUSIONS

The potential for using models in risk assessment to estimate a patient's physiological status, stable or deteriorating, within 4 h has been demonstrated. The study was based on retrospective analysis and further studies are needed to evaluate the impact on clinical outcomes using this model.

Pulse pressure, prehypertension, and mortality: the San Antonio heart study

BACKGROUND

Prehypertension increases mortality risk. Pulse pressure is also associated with increased mortality. Nevertheless, the impact of pulse pressure on the relationship between prehypertension and mortality is not known in individuals who are free of diabetes and cardiovascular disease.

METHODS

Cox regression analysis was used to examine mortality risk among 3,632 (97.0%) participants in the San Antonio Heart Study (age range, 25-64 years; mean follow-up, 15.2 years). Results were adjusted for age, sex, ethnicity, education, body mass index (BMI), smoking, and total cholesterol concentration. The Seventh Report of the Joint Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) categories were used for blood pressure staging: normal, <120/80 mm Hg; prehypertension, 120-139/80-89 mm Hg.

RESULTS

Prehypertension prevalence was 31.6% at baseline. There were 218 deaths during the follow-up period. Prehypertension-predicted mortality (all-cause, hazard ratio (HR) 1.49 (1.12-1.99); cardiovascular, HR 1.79 (1.07-3.02)). Relative to normal blood pressure plus pulse pressure in the lower tertile, prehypertension plus pulse pressure in the upper tertile was associated with increased mortality (all-cause, HR 2.14 (1.38-3.32); cardiovascular, HR 2.47 (1.13-5.39)); however, prehypertension plus pulse pressure in the lower tertile was not significantly associated with mortality (all-cause, HR 1.19 (0.52-2.67); cardiovascular, HR 0.43 (0.05-3.40)).

CONCLUSIONS

Prehypertension increases mortality risk (all-cause and cardiovascular) in individuals who are free of diabetes and cardiovascular disease. Nevertheless, this relationship is not evident in individuals with narrow pulse pressure. Therefore, pulse pressure may be a relevant measure of blood pressure for the definition of normal blood pressure.