Analysis of heart rate variability in individuals subjected to different positive end expiratory pressure levels using expiratory positive airway pressure

Acute cardiac autonomic and hemodynamic responses to resistive breathing: Effect of loading type and intensity

OBJECTIVES

This study aimed to assess the acute impact of distinct loading breathing types and intensities on cardiac autonomic function and hemodynamic responses in healthy young adults.

METHODS

A randomized, crossover trial involved 28 participants who underwent inspiratory resistive breathing, expiratory resistive breathing (ERB) and combined resistive breathing, each at 30% and 60% of maximal respiratory pressures. Data on heart rate variability (HRV) and hemodynamic parameters were collected during each trial.

RESULTS

The study revealed significant main and interaction effects for both the performed task and the intensity across all measured variables (all p < 0.001). ERB at 60% load demonstrated significantly higher HRV values in the standard deviation of normal-to-normal RR intervals, the square root of the mean squared difference of successive normal-to-normal RR intervals and high-frequency power, as well as significantly lower values in heart rate, stroke volume, stroke volume index, cardiac output, cardiac index, end-diastolic volume and end-diastolic volume index, compared to other loaded protocols (all p < 0.001).

CONCLUSION

These findings highlight the acute effect of type-specific and load-dependent resistive breathing on cardiac autonomic and hemodynamic functions, where ERB at 60% intensity showed the most significant cardiovagal modulation while causing the least hemodynamic alterations.

Epidemiology and Risk Factors for Orthostatic Hypotension and Its Severity in Residents Aged > 60 years: A Cross-Sectional Study

This cross-sectional study investigated the epidemiology and risk factors associated with orthostatic hypotension (OH) and its severity in older adults residing in the Jizhou community of Tianjin and the Jimei community of Xiamen. The study, conducted from March to September 2019, involved adults aged over 60. A comprehensive questionnaire survey was administered, resulting in the enrolment of 4383 older adults. The overall prevalence of OH was found to be 11.7% (516 out of 4383). Notably, a significant gender difference was observed, with a prevalence of 10% among males (194 out of 1926) and 13.1% among females (322 out of 2457) (P=0.002). Among individuals with OH, 332 exhibited mild symptoms, 64 had moderate OH, 58 had severe OH cases, and 50 have very severe OH. Multivariable logistic regression analysis revealed that being female, widowed, engaging in general social activities, and a history of hypertension, migraines, heart disease, cerebrovascular disease, and mental health conditions (anxiety and depression) were independently associated with OH. Ordinal logistic regression analysis further confirmed that hypertension, migraine, and a history of general anesthesia surgery were independently associated with the severity of OH. This study highlights a relatively high prevalence of OH among older adults in the Jizhou community of Tianjin and the Jimei community of Xiamen, China. The identified risk factors, particularly social activities, and hypertension, significantly influence the severity of OH. Further examination is required to corroborate these findings and investigate potential interventions.

CPAP and EPAP elicit similar lung deflation in a non-equivalent mode in GOLD 3-4 COPD patients

INTRODUCTION

Lung hyperinflation is associated with inspiratory muscle strength reduction, nocturnal desaturation, dyspnea, altered cardiac function and poor exercise capacity in advanced COPD.

OBJECTIVES

We investigated the responses of inspiratory capacity (IC) and inspiratory muscle strength (PImax), comparing continuous positive airway pressure (CPAP) and expiratory positive airway pressure (EPAP) with the main hypothesis that there would be similar effects on lung deflation.

METHODS

Eligible patients were submitted to 10 cmH₂ O CPAP and EPAP on different days, under careful ECG (HR) and peripheral oxygen saturation (SpO₂ ) monitoring.

RESULTS

Twenty-one eligible COPD patients were studied (13 male/8 female, FEV₁ % predicted of 36.5 ± 9.8). Both CPAP and EPAP demonstrated significant post-pre (Δ) changes for IC and PImax, with mean ΔIC for CPAP and EPAP of 200 ± 100 mL and 170 ± 105 mL (P = .001 for both) in 13 and 12 patients (responders) respectively. There were similar changes in % predicted IC and PImax (∼7%, P = .001 for both) for responders and poor responder/non-responder agreement depending on CPAP/EPAP mode (Kappa = .113, P = .604). There were no differences in CPAP and EPAP regarding intensity of lung deflation (P =.254) and no difference was measured regarding HR (P = .235) or SpO₂ (P = .111)_. CONCLUSIONS: Both CPAP and EPAP presented a similar effect on lung deflation, without guaranteeing that the response to one modality would be predictive of the response to the other.

The effect of postoperative positive end-expiratory pressure on postoperative bleeding after off-pump coronary artery bypass grafting

INTRODUCTION

To compare postoperative prophylactic use of two positive end-expiratory pressure (PEEP) levels in order to prevent postoperative bleeding in patients undergoing off-pump coronary artery bypass grafting (CABG) surgery.

MATERIAL AND METHODS

Sixty patients undergoing an elective off-pump CABG operation were included in this prospective, nonrandomized clinical trial. Patients were divided into two groups as receiving either 5 cm H2O (group 1) or 8 cm H2O PEEP (group 2) after the operation until being extubated. Chest tube outputs, use of blood products and other fluids, postoperative hemoglobin levels, accumulation of pleural and pericardial fluid after the removal of chest tubes, and duration of hospital stay were recorded and compared.

RESULTS

Low- and high-pressure PEEP groups did not differ with regard to postoperative chest tube outputs, amounts of transfusions and crystalloid/colloid infusion requirements, or postoperative hemoglobin levels. However, low-pressure PEEP application was associated with significantly higher pleural (92 ±37 ml vs. 69 ±29 ml, p = 0.03) and pericardial fluid (17 ±5 ml vs. 14 ±6 ml, p = 0.04) accumulation. On the other hand, high-pressure PEEP application was associated with significantly longer duration of hospitalization (6.25 ±1.21 days vs. 5.25 ±0.91 days, p = 0.03).

CONCLUSIONS

Prophylactic administration of postoperative PEEP levels of 8 cm H2O, although safe, does not seem to reduce chest-tube output or transfusion requirements in off-pump CABG when compared to the lower level of PEEP. Further studies with larger sample sizes are warranted to confirm the benefits and identify ideal levels of PEEP administration in this group of patients.