"Effect of Pre-Spinal Mindfulness-Based Breathing Exercise on Hemodynamic Response in Elective Cesarean Section"

Official title

"The Effect of a 5-Minute Mindfulness-Based Breathing Exercise Administered Prior to Spinal Anesthesia on Hemodynamic Response in Patients Undergoing Elective Cesarean Section: A Prospective Randomized Controlled Trial"

Overview

Spinal anesthesia-induced hypotension is one of the most frequent and clinically significant complications of obstetric anesthesia, occurring in up to 50-80% of parturients undergoing elective cesarean section. Preoperative anxiety has been shown to potentiate hemodynamic instability through autonomic nervous system activation, thereby increasing susceptibility to spinal hypotension. This prospective, randomized, controlled trial aims to evaluate the effect of a standardized 5-minute mindfulness-based breathing exercise administered immediately prior to spinal anesthesia on the hemodynamic response in pregnant women scheduled for elective cesarean section. Eligible participants will be randomized in a 1:1 ratio into two parallel groups: the Mindfulness-Based Breathing Exercise Group and the Control Group receiving standard preoperative care. The breathing intervention consists of slow diaphragmatic breathing at a rate of approximately 6 breaths per minute (4-second inhalation through the nose, 6-second exhalation through the mouth), guided by a standardized script delivered by a trained anesthesiologist or nurse. Participants in the intervention group will be instructed to silently repeat the phrase "My body is relaxing as I exhale" with each exhalation, incorporating a mindfulness component. The primary outcome is the maximum decrease in systolic arterial pressure (SAP) within the first 10 minutes following spinal anesthesia induction. Secondary outcomes include preoperative state anxiety scores (STAI-5), early spinal hypotension incidence, heart rate changes, and vasopressor requirements. The study will be conducted at Atatürk University Faculty of Medicine, Department of Anesthesiology and Reanimation, Erzurum, Turkey, in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines.

Detailed description

Background and Rationale Spinal anesthesia-induced hypotension is the most common hemodynamic complication in obstetric anesthesia, with reported incidence rates ranging from 50% to 80% in parturients undergoing elective cesarean section. The underlying pathophysiology involves sympathetic blockade-mediated arteriolar and venous vasodilation, resulting in decreased systemic vascular resistance and reduced venous return, further compounded by aortocaval compression exerted by the gravid uterus.

Current prophylactic strategies including left uterine displacement, fluid co-loading, and vasopressor infusion remain the standard of care. However, these pharmacological approaches may be associated with tachycardia, hypertension, and inter-individual response variability, underscoring the need for complementary non-pharmacological interventions.

Preoperative anxiety exerts measurable effects on autonomic nervous system balance, potentially amplifying sympathetic tone and increasing hemodynamic instability following neuraxial blockade. Slow, controlled breathing exercises have been shown to enhance baroreflex sensitivity and augment parasympathetic vagal activity, suggesting that a brief mindfulness-based breathing intervention may attenuate sympathetic hyperactivity through an "autonomic preconditioning" mechanism.

Randomization and Allocation Concealment Participants will be randomized in a 1:1 ratio using a computer-generated random number sequence. Allocation concealment will be ensured through sequentially numbered, opaque, sealed envelopes (SNOSE), opened only after the patient has been transferred to the operating room and immediately before spinal anesthesia induction.

Intervention Protocol Participants in the intervention arm will receive a 5-minute guided mindfulness-based breathing exercise prior to spinal anesthesia, consisting of slow diaphragmatic breathing at approximately 6 breaths per minute (4-second nasal inhalation, 6-second oral exhalation). During each exhalation, participants silently repeat: "My body is relaxing as I exhale."

Anesthesia Management All participants will receive spinal anesthesia in the sitting position with intrathecal administration of 11.2 mg hyperbaric bupivacaine + 15 mcg fentanyl + 150 mcg morphine. Hypotension will be defined as a decrease in systolic arterial pressure (SAP) exceeding 20% from baseline and treated with norepinephrine or ephedrine. Bradycardia will be defined as heart rate ≤50 bpm and treated with intravenous atropine (1 mg).

Statistical Analysis All analyses will be performed using IBM SPSS Statistics (Statistical Package for the Social Sciences) version 20. Normality will be assessed using Shapiro-Wilk and Kolmogorov-Smirnov tests. Between-group comparisons will be performed using independent samples t-test or Mann-Whitney U test as appropriate. Categorical variables will be compared using chi-square test. Statistical significance will be set at p\<0.05.

Sample Size Sample size was calculated using G\*Power 3.1.9.7 software. A clinically meaningful difference of 4.5 mmHg in maximum SAP decrease (effect size = 0.48) was determined to require 70 participants per group at 80% power and 95% confidence level. Accounting for potential dropout, 150 participants (75 per group) will be enrolled.

Interventions

• Behavioral Mindfulness-Based Breathing Exercise
  "A standardized 5-minute mindfulness-based breathing exercise at approximately 6 breaths per minute (4-second nasal inhalation, 6-second oral exhalation), guided by a trained anesthesiologist or nurse using a standardized verbal script. During each exhalation, participants silently repeat: 'My body is relaxing as I exhale.'"

Primary outcome measures

• Maximum Decrease in Systolic Arterial Pressure (ΔSAP_max) Following Spinal Anesthesia [Time frame: Up to 10 minutes following spinal anesthesia induction"]

Secondary outcome measures (7)

• Change in Preoperative State Anxiety Score (ΔSTAI-S5) [Time frame: "Baseline and up to 5 minutes prior to spinal anesthesia induction"]
• Incidence of Early Spinal Hypotension [Time frame: "Up to 10 minutes following spinal anesthesia induction"]
• Maximum Heart Rate Decrease (ΔHR_max) Following Spinal Anesthesia [Time frame: "Up to 10 minutes following spinal anesthesia induction"]
• Time to First Hypotensive Episode [Time frame: "During surgery, up to approximately 60 minutes following spinal anesthesia induction"]
• Proportion of Participants Requiring Vasopressor Therapy [Time frame: "Up to 10 minutes following spinal anesthesia induction"]
• Total Vasopressor Dose Administered [Time frame: "Up to 10 minutes following spinal anesthesia induction"]
• Lowest Systolic Arterial Pressure (SAP_min) Following Spinal Anesthesia [Time frame: "Up to 10 minutes following spinal anesthesia induction"]

Eligibility criteria

Inclusion criteria

Pregnant women aged 18-45 years Singleton pregnancy Gestational age 37 weeks or greater American Society of Anesthesiologists (ASA) physical status classification II Scheduled for elective cesarean section under spinal anesthesia Body mass index (BMI) 35 kg/m2 or less Ability to comprehend verbal instructions and perform the breathing exercise Provision of written informed consent

Exclusion criteria

Emergency cesarean section Hypertensive disorders of pregnancy (gestational hypertension, preeclampsia, eclampsia, HELLP syndrome) Placenta previa, placental abruption, or active antepartum hemorrhage Multiple pregnancy Contraindications to spinal anesthesia Failed spinal anesthesia requiring conversion to general anesthesia Chronic hypertension or chronic hypotension Known cardiac disease (arrhythmia, valvular disease, cardiomyopathy) Diabetes mellitus with autonomic neuropathy Thyroid dysfunction Chronic pulmonary disease potentially affecting respiratory pattern Body mass index greater than 35 kg/m2 Regular use of beta-blockers, calcium channel blockers, alpha-agonists, or alpha-antagonists Regular use of anxiolytics, antidepressants, sedatives, or chronic opioids Diagnosed anxiety disorder, panic disorder, major depressive disorder, or other psychiatric illness Regular use of psychiatric medications Cognitive impairment or communication difficulties Attention or compliance problems precluding adequate performance of the breathing exercise Prior regular practice of meditation, yoga, or mindfulness-based training

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Single blind

Primary purpose

Prevention

Study locations

Turkey (Türkiye) · 1 center

• Atatürk University Research Hospital — Erzurum

Publications

• Walker AP, McCormack ML, Messier J, Myers-Smith IH, Wullschleger SD. Trait covariance: the functional warp of plant diversity? New Phytol. 2017 Dec;216(4):976-980. doi: 10.1111/nph.14853. No abstract available. PMID 29110312
• Teixeira AG, Silva AS, Lin FL, Velletri R, Bavia L, Belfort R Jr, Isaac L. Association of complement factor H Y402H polymorphism and age-related macular degeneration in Brazilian patients. Acta Ophthalmol. 2010 Aug;88(5):e165-9. doi: 10.1111/j.1755-3768.2010.01932.x. Epub 2010 Jul 6. PMID 20626361
• Russo MA, Santarelli DM, O'Rourke D. The physiological effects of slow breathing in the healthy human. Breathe (Sheff). 2017 Dec;13(4):298-309. doi: 10.1183/20734735.009817. PMID 29209423
• Shaffer F, Ginsberg JP. An Overview of Heart Rate Variability Metrics and Norms. Front Public Health. 2017 Sep 28;5:258. doi: 10.3389/fpubh.2017.00258. eCollection 2017. PMID 29034226

Identifiers

NCT: NCT07494955 · B.30.2.ATA.0.01.00/127

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗