Effects of Alternate Nostril Breathing Versus Diaphragmatic Breathing on Oxygen Saturation and Heart-rate Variability in Post Percutaneous Coronary Intervention Patients

This randomized parallel group study will enroll hemodynamically stable post-PCI inpatients referred by cardiology at the CCU of Fauji foundation Hospital, Rawalpindi. Eligible participants will be screened according to predefined inclusion and exclusion criteria and will provide written informed consent before participation. Participants will be randomly allocated in a 1:1 ratio to alternate nostril breathing or diaphragmatic breathing using sealed opaque envelopes. Both interventions will be supervised by a physiotherapist and provided in addition to routine care for 2 consecutive days with three sessions per day. Each session will be approximately 15 minutes with 10 repetitions on post-PCI Day 0 and approximately 20 minutes with 15 repetitions on Day-1. Heart-rate , blood pressure, respiratory rate and oxygen saturation will be monitored before and after sessions. The intervention will be stopped in the presence of clinically significant symptoms or abnormal vital-sign changes and the participant will be referred to the CCU medical team when required. Oxygen saturation and heart-rate variability will be assessed at baseline and after completion of the 2-day intervention period.

• Alternate Nostril Breathing (Behavioral): Non-pharmacological breathing interventions administered under physiotherapist supervision for 2 consecutive days with three sessions per day in addition to routine post-PCI care.
• Diaphragmatic breathing (Other): Participants assigned to this group will perform diaphragmatic breathing under physiotherapist supervision in addition to routine post-PCI care. The participant will lie supine or sit upright with the back supported, with one hand on the upper chest and the other on the abdomen below the rib cage. The participant will inhale slowly through the nose while allowing the abdomen to rise and then exhale slowly through pursed lips while allowing the abdomen to fall. Post-PCI Day 0 : 3 sessions/day approximately 15mins/session,10 repetitions. Post-PCI Day 1 :3 supervised sessions/day approximately 20 minutes/session, 15 repetitions.

Primary outcomes

• Change in Oxygen saturation [Baseline and immediately after completion of the 2-day intervention period.]: Change in peripheral oxygen saturation (SpO₂) from baseline to the specified post-intervention assessment time point, measured using a pulse oximeter. Oxygen saturation will be recorded as a percentage (%) and compared between baseline and post-intervention measurements.
• Change in Heart Rate Variability (HRV) [Baseline and immediately after completion of the 2-day intervention period.]: Change in heart rate variability from baseline to the specified post-intervention assessment time point, assessed using a validated heart rate/ECG monitoring device. Heart rate variability will be evaluated using predefined HRV parameters, such as time-domain and/or frequency-domain measures, as applicable to the study protocol.

Sex: All, ages: 44 Years to 75 Years

Inclusion Criteria:

* Adults aged 44-75 years
* Hemodynamically stable post-PCI patients with systolic blood pressure>90 mmHg, diastolic BP 50-100mmHg Heart-rate 60-100 beats/min and no ongoing chest pain or signs of acute clinical instability.
* Oxygen saturation >92% on room air
* Able to follow simple verbal instructions and perform the breathing exercises.
* Ejection Fraction >35%

Exclusion Criteria:

* Ongoing myocardial ischemia, unstable angina, significant arrythmia or requirement for inotropic/vasopressor support.
* Cardiogenic shock or severe heart failure (NYHA class IV)
* Recent thoracic surgery or chest wall injury limiting rib expansion or deep breathing.
* Cardiac implantable electronic device (pacemaker/ICD) with pacing dependency or an implanted ventricular assist device.
* Severe cognitive impairment
* Uncontrolled hypertension(SBP>180 mmHg or DBP>110 mmHg) or bradycardia<50 beats/min.
* Severe anemia (Hb<8g/dL)