European Journal of Cardiovascular Medicine

Spinal anaesthesia remains the preferred anaesthetic technique for cesarean delivery due to its rapid onset, excellent surgical conditions, and maternal safety profile.[1] However, spinal anaesthesia-induced hypotension (SAIH) occurs in 70-80% of parturients, representing one of the most common and potentially serious complications associated with neuraxial blockade during cesarean section.[2,3] This precipitous drop in maternal blood pressure can lead to maternal symptoms including nausea, vomiting, and altered consciousness, while simultaneously compromising uteroplacental perfusion and potentially resulting in fetal acidosis and adverse neonatal outcomes.[4,5]

The pathophysiology of SAIH is multifactorial, involving sympathetic blockade-induced peripheral vasodilation, reduced venous return, decreased cardiac preload, and subsequent reduction in cardiac output.[6] In the obstetric population, these hemodynamic changes are further complicated by pregnancy-induced physiological alterations, including increased plasma volume, reduced systemic vascular resistance, and aortocaval compression.[7,8]

Traditional approaches to prevent SAIH have included fluid preloading, vasopressor administration, and left uterine displacement, with varying degrees of success.[9] However, the ability to predict which patients are at highest risk remains limited using conventional assessment methods. Recent advances in point-of-care ultrasound (POCUS) have introduced novel, non-invasive approaches to assess cardiovascular status and fluid responsiveness.[10,11]

Tricuspid annular plane systolic excursion (TAPSE) has emerged as a reliable echocardiographic parameter for assessing right ventricular systolic function, serving as a surrogate marker for right ventricular contractility and overall cardiac performance.[12,13] TAPSE has demonstrated strong correlations with hemodynamic stability in non-obstetric populations.[14] The ease of acquisition and reproducibility make it attractive for perioperative use.[15]

Carotid flow time (CFT) reflects cardiac preload and intravascular volume status, measured as the duration of systolic flow in the carotid artery.[16,17] When combined with passive leg raising (PLR), CFT provides dynamic assessment of preload responsiveness.[18] The PLR manoeuvre serves as an endogenous fluid challenge, temporarily increasing venous return and unmasking latent hypovolemia.[19,20]

Limited data exist comparing TAPSE and CFT-PLR efficacy in predicting SAIH in the obstetric population. The unique physiological changes of pregnancy may influence the performance characteristics of these predictive tools.[21,22] Therefore, this prospective observational study compared the predictive accuracy of TAPSE versus CFT-PLR for identifying parturients at risk for spinal anaesthesia-induced hypotension during cesarean delivery.

This prospective observational study was conducted at the Department of Anaesthesiology, Sri Devaraj Urs Medical College, Tamaka, Kolar, following Institutional Ethics Committee approval and written informed consent from all participants in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. Study Design and Sample Size This was a prospective observational study with a duration of 3 months. Sample size was estimated based on Cohen's d effect size of 0.9 between TAPSE and CFT with 95% confidence and 80% power. A total of 30 parturients were enrolled and randomly allocated using computer-generated randomization into two equal groups of 15 patients each: the TAPSE group and the CFT-PLR group. Selection Criteria Inclusion criteria: parturients aged 18-40 years, singleton pregnancies ≥37 weeks, ASA I-II, scheduled elective cesarean delivery under spinal anaesthesia, BMI <35 kg/m². Exclusion criteria: pre-existing cardiovascular disease, pregnancy-induced hypertension, preeclampsia, valvular heart disease, arrhythmias, gestational diabetes, contraindications to spinal anaesthesia, multiple pregnancies, polyhydramnios, placental abnormalities, inadequate ultrasound windows, conversion to general anaesthesia. Ultrasound Assessments TAPSE Group: Preoperative measurements in left lateral position using phased array transducer (1-5 MHz) to obtain apical four-chamber view. M-mode placed through lateral tricuspid annulus. Distance between lowest diastolic and highest systolic points measured; average of two readings recorded. CFT-PLR Group: Baseline carotid Doppler using Philips Innosight with linear transducer (4-12 MHz). Right common carotid artery imaged at lower thyroid cartilage border. Angle-corrected spectral Doppler with 0.5 mm sample gate, insonation angle <60°. Corrected CFT calculated: FTcorrected = FTmeasured + 1.29 × (HR - 60). PLR performed by elevating foot to 45°; measurements repeated within 60 seconds. Anaesthetic Procedure Standard pre-anaesthetic evaluation and fasting (6 hours solids, 2 hours clear fluids). Spinal anaesthesia at L3-L4 using 25G Quincke needle, midline approach, 10 mg hyperbaric bupivacaine. Supine positioning with right buttock wedge. Crystalloid co-loading 10 mL/kg. Hemodynamic Monitoring and Management HR, SBP, DBP, MAP, SpO₂, respiratory rate recorded at baseline and every 5 minutes intraoperatively. Hypotension defined as MAP decrease >25% from baseline, treated with crystalloid co-loading and mephentermine 6 mg boluses. Statistical Analysis SPSS version 29. Categorical data: frequencies and proportions, Chi-square/Fisher's exact test. Continuous data: mean ± SD, independent t-test. ROC curves for predictive accuracy. P<0.05 considered significant.

Study Population and Baseline Characteristics

Thirty parturients were enrolled: 15 in TAPSE group, 15 in CFT-PLR group. Groups were comparable in demographics and baseline characteristics (Table 1). Mean age was 28.6 ± 3.8 years (TAPSE) vs. 27.9 ± 4.2 years (CFT-PLR), p=0.642. BMI showed no difference (26.2 ± 2.9 vs. 26.8 ± 3.2 kg/m², p=0.602). Gestational age was similar (38.5 ± 1.0 vs. 38.3 ± 1.2 weeks, p=0.638). ASA status distribution balanced with majority ASA I (73.3% vs. 66.7%). Baseline hemodynamics comparable (all p>0.05), confirming successful randomization.

Data presented as mean ± SD or n. TAPSE = Tricuspid Annular Plane Systolic Excursion; CFT-PLR = Carotid Flow Time with Passive Leg Raising; BMI = Body Mass Index; ASA = American Society of Anesthesiologists; HR = Heart Rate; SBP = Systolic Blood Pressure; DBP = Diastolic Blood Pressure; MAP = Mean Arterial Pressure.

Ultrasound Measurements

TAPSE group mean was 19.3 ± 3.5 mm (Table 2). Patients developing hypotension had significantly lower TAPSE (16.9 ± 2.7 mm) versus normotensive (23.5 ± 2.2 mm). CFT-PLR group baseline CFT was 319.2 ± 29.4 ms, increasing to 333.1 ± 32.0 ms post-PLR (ΔCFT 13.9 ± 8.6 ms). Hypotensive patients showed smaller CFT increase (8.4 ± 4.5 ms) versus normotensive (24.8 ± 7.1 ms), indicating impaired preload responsiveness. Adequate windows obtained in 93.3% (TAPSE) and 100% (CFT-PLR), p=0.483. TAPSE faster (3.1 ± 0.8 vs. 5.4 ± 1.3 minutes, p<0.001).

Table 1: Demographic and Baseline Characteristics

Table 2: Ultrasound Measurements and Distribution

Data presented as mean ± SD or n (%). TAPSE = Tricuspid Annular Plane Systolic Excursion; CFT = Carotid Flow Time; PLR = Passive Leg Raising.

Incidence and Characteristics of Hypotension

Hypotension occurred in 11 (73.3%) TAPSE and 10 (66.7%) CFT-PLR patients (p=0.705, Table 3). Severity distribution comparable: mild (25-30% MAP decrease) 33.3% vs. 26.7%, moderate (30-40%) 26.7% vs. 33.3%, severe (>40%) 13.3% vs. 6.7% (all p>0.05). Time to hypotension similar (8.2 ± 3.4 vs. 8.7 ± 3.8 minutes, p=0.719). Lowest MAP 63.2 ± 8.9 vs. 64.8 ± 9.4 mmHg (p=0.645). Vasopressor required in 73.3% vs. 66.7%; mean mephentermine 13.8 ± 7.2 vs. 13.2 ± 7.6 mg (p=0.827), averaging 2.3 ± 1.2 vs. 2.2 ± 1.3 boluses (p=0.821). Crystalloid volumes comparable (858 ± 148 vs. 892 ± 162 mL, p=0.567). Bradycardia minimal (6.7% vs. 6.7%); nausea/vomiting (20.0% vs. 13.3%, p=0.637). No fetal distress. Sensory level predominantly T4 (80% vs. 73.3%). Surgical duration similar (41.8 ± 8.9 vs. 43.6 ± 9.5 minutes, p=0.610).

Table 3: Hemodynamic Outcomes and Complications

Data presented as mean ± SD or n (%). MAP = Mean Arterial Pressure; HR = Heart Rate; NICU = Neonatal Intensive Care Unit.

Neonatal Outcomes

Neonatal outcomes were reassuring in both groups (Table 3). Mean Apgar scores at 1 minute were 8.5 ± 0.7 and 8.6 ± 0.8 in the TAPSE and CFT-PLR groups, respectively (p=0.729). Apgar scores at 5 minutes were excellent in both groups (9.3 ± 0.6 vs. 9.4 ± 0.7, p=0.686). No neonates required admission to the neonatal intensive care unit in either group, indicating that the observed episodes of maternal hypotension did not adversely affect immediate neonatal outcomes when promptly managed.

Predictive Performance

ROC analysis identified optimal cutoffs: TAPSE ≤18.5 mm, ΔCFT ≤12 ms (Table 4). TAPSE: sensitivity 81.8% (95% CI: 52.3-94.9%), specificity 75.0% (30.1-95.4%), PPV 90.0% (59.6-98.2%), NPV 60.0% (23.1-88.2%), AUC 0.848 (0.625-0.961). CFT-PLR: sensitivity 80.0% (49.0-94.3%), specificity 80.0% (37.6-96.4%), PPV 88.9% (56.5-98.0%), NPV 66.7% (30.0-90.3%), AUC 0.870 (0.652-0.970). AUC difference non-significant (p=0.762). Positive likelihood ratios high (3.27 vs. 4.00); negative low (0.24 vs. 0.25). Accuracy 80.0% vs. 80.0%.

Table 4: Predictive Performance for Spinal Anaesthesia-Induced Hypotension

CI = Confidence Interval; TAPSE = Tricuspid Annular Plane Systolic Excursion; CFT-PLR = Carotid Flow Time with Passive Leg Raising; ROC = Receiver Operating Characteristic.

Correlation Analysis

Strong correlations were observed between ultrasound parameters and hemodynamic outcomes (Table 5). In the TAPSE group, TAPSE values showed significant positive correlation with lowest MAP (r=0.712, p<0.001) and time to hypotension (r=0.534, p=0.008), and significant negative correlation with total vasopressor dose required (r=-0.673, p=0.001). In the CFT-PLR group, change in carotid flow time (ΔCFT) demonstrated strong positive correlation with lowest MAP (r=0.738, p<0.001) and time to hypotension (r=0.582, p=0.004), and strong negative correlation with vasopressor dose (r=-0.695, p<0.001). Baseline CFT before PLR also showed significant correlation with hypotension occurrence (r=-0.478, p=0.019).

Table 5: Correlation Analysis

TAPSE = Tricuspid Annular Plane Systolic Excursion; CFT = Carotid Flow Time; PLR = Passive Leg Raising; MAP = Mean Arterial Pressure; ΔCFT = Change in Carotid Flow Time.

Feasibility and Operator Assessment

Both ultrasound techniques were found to be feasible for clinical implementation (Table 6). TAPSE was rated as easier to acquire on a 5-point scale (4.1 ± 0.6 vs. 3.7 ± 0.7, p=0.042), likely reflecting its single-position measurement requirement. Image quality was excellent for both techniques (4.0 ± 0.7 vs. 4.2 ± 0.6, p=0.318). The learning curve was significantly shorter for TAPSE (8.2 ± 2.3 cases) compared to CFT-PLR (12.4 ± 3.6 cases, p<0.001). Both techniques demonstrated good repeatability with coefficients of variation of 8.4 ± 2.5% for TAPSE and 7.8 ± 2.2% for CFT-PLR (p=0.489). Inter-observer variability was low and comparable (7.1% vs. 7.5%, p=0.842). Patient discomfort was minimal but significantly lower for TAPSE (1.5 ± 0.9 vs. 2.7 ± 1.3, p<0.001). Technical failure occurred in only one case (6.7%) in the TAPSE group (p=0.483).

Table 6: Feasibility and Operator Assessment

*5-point scale: 1 = very difficult/poor, 5 = very easy/excellent. **10-point scale: 0 = no discomfort, 10 = severe discomfort. Data presented as mean ± SD or n (%). CV = Coefficient of Variation.

This prospective observational study compared two POCUS methods for predicting SAIH in parturients. Our findings demonstrate both TAPSE and CFT-PLR are effective predictive tools with distinct practical advantages and comparable accuracy.

The 66.7-73.3% hypotension incidence in our study is consistent with published literature reporting 70-80% rates in parturients undergoing spinal anaesthesia for cesarean delivery.[2,3] This underscores the clinical importance of reliable predictive tools that can guide prophylactic interventions and optimize perioperative management.

TAPSE demonstrated excellent predictive performance with an AUC of 0.848 and optimal cutoff of ≤18.5 mm. As a marker of right ventricular function, TAPSE provides rapid assessment that can be particularly valuable in time-sensitive clinical scenarios. The mean assessment time of 3.1 minutes and shorter learning curve (8.2 cases) make it accessible to anaesthesiologists with basic echocardiographic training. Our findings align with recent studies by Gülaştı et al. suggesting TAPSE utility in predicting hemodynamic responses to spinal anaesthesia in cesarean section.[23]

CFT-PLR showed slightly superior predictive performance with an AUC of 0.870, though the difference was not statistically significant (p=0.762). The dynamic assessment through the PLR manoeuvre provides insights into preload responsiveness that may be particularly relevant in obstetric populations where fluid status management is crucial. The ΔCFT cutoff of ≤12 ms effectively identified patients with limited hemodynamic reserve who were at highest risk for hypotension. Our results support the findings of Kim et al. that carotid artery flow measurements can predict spinal anaesthesia-induced hypotension.[24]

The strong correlations (r>0.70) between ultrasound parameters and hemodynamic outcomes validate the physiological rationale for both methods. Lower TAPSE values and smaller changes in CFT with PLR were associated with more severe hypotension, earlier onset, and greater vasopressor requirements. These relationships confirm that both parameters reflect cardiovascular reserve and fluid responsiveness in this patient population.

Both methods demonstrated high positive predictive values (88.9-90.0%), suggesting excellent clinical utility in identifying high-risk patients who would benefit from aggressive prophylactic measures such as increased fluid preloading or prophylactic vasopressor administration. The negative predictive values (60.0-66.7%) indicate that some hypotensive patients may not be identified by either method alone, highlighting the need for vigilant monitoring regardless of initial assessment.

Feasibility analysis revealed important practical differences between the two methods. TAPSE's faster assessment time, easier acquisition, and shorter learning curve favour its use when rapid preoperative evaluation is needed. The additional time required for CFT-PLR assessment (5.4 vs. 3.1 minutes) and slightly higher patient discomfort related to the PLR manoeuvre are offset by the dynamic information on preload responsiveness. The choice between methods may depend on institutional resources, operator expertise, available time, and specific clinical contexts.

The excellent neonatal outcomes observed in this study, with no NICU admissions despite a 70% maternal hypotension incidence, demonstrate that appropriate hemodynamic management can prevent adverse neonatal effects. This supports the use of aggressive treatment protocols when hypotension is identified or predicted, and validates the clinical utility of both POCUS methods in enabling timely interventions.

Limitations: This study has several limitations. The single-center design and relatively small sample size may limit generalizability and statistical power for subgroup analyses. We did not compare these methods against invasive hemodynamic monitoring as a gold standard. The study population was relatively healthy (ASA I-II), limiting applicability to higher-risk parturients with pre-existing cardiovascular disease or pregnancy complications. We did not assess the cost-effectiveness of implementing these POCUS methods. Future multi-center studies with larger, more diverse populations and cost-effectiveness analyses are warranted to validate these findings and establish standardized protocols for clinical implementation.

Clinical Implications: These findings suggest both POCUS methods can be integrated into routine preoperative assessment for caesarean delivery under spinal anaesthesia. Patients identified as high-risk could receive tailored prophylaxis including aggressive fluid management, prophylactic vasopressor infusions, or consideration of alternative anaesthetic techniques. Implementation would require institutional commitment to training programs, equipment acquisition, and protocol development. The choice between TAPSE and CFT-PLR may be individualized based on institutional factors and clinical scenarios.

Both TAPSE and carotid flow time with passive leg raising effectively predict spinal anaesthesia-induced hypotension in parturients undergoing caesarean delivery, with comparable accuracy (AUC 0.848 vs. 0.870, p=0.762). TAPSE offers faster assessment (3.1 vs. 5.4 minutes) with a shorter learning curve, making it ideal for rapid preoperative evaluation. CFT-PLR provides dynamic preload assessment that may offer additional physiological insights. Both techniques demonstrate high feasibility, good reproducibility, and strong correlations with hemodynamic outcomes. The choice between methods should be guided by clinical context, operator expertise, available time, and institutional resources. Implementation of either method could enable personalized prophylactic interventions to improve maternal and neonatal outcomes in obstetric anaesthesia practice.

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