Focused cardiac ultrasound is feasible in parturients; a prospective observational study

Feasibility of Focused Cardiac Ultrasound Performed by Trainees During Cesarean Delivery

BACKGROUND

Anesthesiology experts advocate for formal education in maternal critical care, including the use of focused cardiac ultrasound (FCU) in high-acuity obstetric units. While benefits and feasibility of FCU performed by experts have been well documented, little evidence exists on the feasibility of FCU acquired by examiners with limited experience. The primary aim of this study was to assess how often echocardiographic images of sufficient quality to guide clinical decision-making were attained by trainees with limited experience performing FCU in term parturients undergoing cesarean delivery (CD).

METHODS

In this prospective cohort study, healthy term parturients (American Society of Anesthesiologists [ASA] ≤ 3, ≥37 weeks of gestation) with singleton pregnancy, body mass index (BMI) <40 kg/m 2 , and no history of congenital and acquired cardiac disease undergoing scheduled, elective CD were recruited by a trainee. After undergoing standardized training, including an 8-hour online E-learning module, a 1-day hands-on FCU course, and 20 to 30 supervised scans until the trainee was assessed competent in image acquisition, 8 trainees with limited FCU experience performed apical 4-chamber (A4CH), parasternal long-axis (PLAX), and short-axis (PSAX) view preoperatively after spinal anesthesia (SPA) and intraoperatively after neonatal delivery (ND). Obtained FCU images were graded 1 to 5 by 2 blinded instructors (1 = no image to 5 = perfect image obtainable; ≥3 defined as image quality sufficient for clinical decision-making).

RESULTS

Following the screening of 95 women, 8 trainees with limited FCU experience each performed a median of 5 [3-8] FCUs in a total of 64 women. Images of sufficient quality were obtainable in 61 (95.3 %) and 57 (89.1 %) of women after SPA and ND, respectively. FCU images of perfect image quality were obtainable in 9 (14.1 %) and 7 (10.9 %) women preoperatively after SPA and intraoperatively after ND, respectively. A PLAX, PSAX, and A4CH view with grade ≥3 was obtained in 53 (82.8 %), 58 (90.6 %) and 40 (62.5 %) of women preoperatively after SPA and in 50 (78.1 %), 49 (76.6 %), and 29 (45.3 %) of women intraoperatively after ND. Left ventricular function could be assessed in 39 of 40 women (97.5 %) preoperatively after SPA and 39 of 40 (97.5%) intraoperatively after ND. Right ventricular function could be assessed in 31 of 40 (77.5 %) after SPA and in 23 of 40 (59%) after ND. We observed a difference in image grading between different trainees in the AP4CH-view ( P = .0001). No difference in image grading was found between preoperative and intraoperative FCUs.

CONCLUSIONS

FCU is feasible in the parturient undergoing CD and images of sufficient quality for clinical decision-making were obtained by trainees with limited experience in almost all parturients. Image acquisition and quality in the A4CH view may be impacted by the individual trainee performing the FCU.

Exploring the predictive value of combined ultrasound parameters for spinal anesthesia-induced hypotension in cesarean section: a prospective observational study

BACKGROUND

Prophylactic vasopressor infusion can effectively assist with fluid loading to prevent spinal anesthesia-induced hypotension. However, the ideal dose varies widely among individuals. We hypothesized that hypotension-susceptible patients requiring cesarean section (C-section) could be identified using combined ultrasound parameters to enable differentiated prophylactic medical interventions.

METHODS

This prospective observational trial was carried out within a regional center hospital for women and children in Sichuan Province, China. Singleton pregnant women undergoing combined spinal-epidural anesthesia for elective C-sections were eligible. Women with contraindications to spinal anesthesia or medical comorbidities were excluded. Velocity time integral (VTI) and left ventricular end-diastolic area (LVEDA) in the supine and left lateral positions were measured on ultrasound before anesthesia. Stroke volume, cardiac output, and the percentage change (%) in each parameter between two positions were calculated. Vital signs and demographic data were recorded. Spinal anesthesia-induced hypotension was defined as a mean arterial pressure decrease of > 20% from baseline. The area under the receiver operating characteristic curve (AUROC) was used to analyze the associations of ultrasound measurements, vital signs, and demographic characteristics with spinal anesthesia-induced hypotension. This exploratory study did not have a predefined outcome; however, various parameter combinations were compared using the AUROC to determine which combined parameters had better predictive values.

RESULTS

Patients were divided into the normotension (n = 31) and hypotension groups (n = 57). A combination of heart rate (HR), LVEDA_s, and VTI% was significantly better at predicting hypotension than was HR (AUROC 0.827 vs. 0.707, P = 0.020) or LVEDA_s (AUROC 0.827 vs. 0.711, P = 0.039) alone, but not significantly better than VTI% alone (AUROC 0.827 vs. 0.766, P = 0.098).

CONCLUSION

The combined parameters of HR and LVEDA_s with VTI% may predict spinal anesthesia-induced hypotension more precisely than the single parameters. Future research is necessary to determine whether this knowledge improves maternal and neonatal outcomes.

TRIAL REGISTRATION

ChiCTR1900025191.

Focused cardiac ultrasound in pregnancy

Cardiac disease in pregnancy is an important cause of maternal morbidity and mortality. In many high-income countries, acquired cardiac disease is now the largest cause of maternal mortality. Given its prevalence in low- and middle-income countries (LMICs), rheumatic heart disease is the most common cause of cardiac disease in pregnancy worldwide and is associated with poor maternal outcome. The diagnosis of cardiac disease in pregnancy is often delayed resulting in excess maternal morbidity and mortality. Maternal mortality review committees have suggested that prompt recognition and treatment of heart disease in pregnancy may improve maternal outcome. Given the similarities between symptoms of normal pregnancy and those of cardiac disease, the clinical diagnosis of heart disease in pregnancy is challenging with echocardiography being the primary diagnostic modality. Focused cardiac ultrasound (FOCUS) at the point of care provides supplemental data to the history and physical examination and has been demonstrated to permit early diagnosis and improvement in the management of cardiac disease in emergency medicine, intensive care, and anesthesia. It has also been demonstrated to be useful in surveillance for rheumatic heart disease in LMICs. The use of FOCUS may allow earlier and more accurate diagnosis of cardiac disease in pregnancy with the potential to decrease morbidity and mortality in both developed and developing countries.

Inferior vena cava assessment in term pregnant women using ultrasound: A comparison of the subcostal and right upper quadrant views

Point-of-care ultrasound can be used at the bedside to assess the haemodynamic status and fluid responsiveness of a pregnant woman. Previous studies demonstrated that views from the apical and parasternal windows are readily obtainable in labouring women. However, using the subcostal window to assess the inferior vena cava can be challenging because of the gravid uterus. A potential alternative is the right upper quadrant transhepatic window. We sought to compare visualisation of the inferior vena cava via the subcostal and right upper quadrant windows, in full-term pregnant women. This was a prospective pilot study carried out in a tertiary academic obstetric centre. Thirty pregnant non-labouring women at full term were recruited. In each patient, the inferior vena cava was visualised through both the subcostal and the right upper quadrant windows. Time to acquire each image, acquisition success rates and ease of obtaining images were compared for both approaches. Image quality was then reviewed and rated by two independent expert reviewers. There was a significant difference in the time required to obtain each view; subcostal median (interquartile range): 52 (35-59) seconds, right upper quadrant median (interquartile range): 23 (11-55) seconds (P=0.0045). Operator-defined successful image acquisition was 100% for the right upper quadrant window compared to 80% for the subcostal window. Ease of obtaining the view, as rated by the operator, was significantly easier in the right upper quadrant window compared to the subcostal window (P <0.0001). Both reviewers independently rated image adequacy to be significantly greater in the right upper quadrant window (73% and 57%) compared to the subcostal window (40% and 10%) (P=0.0213 and P=0.0005, respectively). Inter-rater agreement ranged between good (Cohen's kappa coefficient 0.64) for right upper quadrant windows to fair (Cohen's kappa coefficient 0.29) for subcostal windows. Inferior vena cava visualisation in term pregnant patients may take less time, be easier and provide better quality images when the right upper quadrant window is used compared to the subcostal window.

A Two Parameters for the Evaluation of Hypovolemia in Patients with Septic Shock: Inferior Vena Cava Collapsibility Index (IVCCI), Delta Cardiac Output

Background

The aim of this study was to determine the correlation between inferior vena cava collapsibility index and changes in cardiac output measured during passive leg raising test in patients with spontaneous breathing and septic shock.

Material/Methods

Fifty-six patients were included in the study. All of these 56 patients were diagnosed with septic shock and had spontaneous breathing under continuous positive airway pressure. Patients exclusions included: patients with cardiac pathology, not septic shock, pregnant, spontaneous breathing, increased intra-abdominal pressure, inferior vena cava could not be visualized, arrhythmia and pulmonary hypertension.

Exclusion criteria for the study were as follows: 1) left ventricular systolic dysfunction, 2) cardiomyopathy, 3) medium severe heart valve disease, 4) patients with arrhythmia; 5) pulmonary hypertension, 6) patients without spontaneous breathing (for inferior vena cava collapsibility index, it is not evaluated), 7) patients with >60 mmHg CO₂ in arterial blood gas; 8) pregnant patients; 9) patients with neurogenic shock, cerebrovascular incident or traumatic brain injury, 10) patients whose inferior vena cava and parasternal long axis cannot be visualized, and 11) patients with increased intra-abdominal pressure.

Patients were placed in neutral supine position, and the inferior vena cava collapsibility index and cardiac output 1 were recorded. In passive leg raising test, after which the cardiac output 2 is recorded in terms of L/min. The percentage increase between the 2 cardiac outputs was calculated and recorded.

Results

A moderately positive correlation was also observed between the inferior vena cava collapsibility index and delta cardiac output (r=0.459; r2=0.21), which was statistically significant (P<0.001). The cutoff value for the delta cardiac output was 29.5.

Conclusions

In conclusion, we found that the inferior vena cava collapsibility index, which is one of the dynamic parameters used in the diagnosis of hypovolemia in patients with septic shock, is correlated with delta cardiac output after leg raising test. We believe that, based on a clinician’s experience, looking at 1 of these 2 parameters is sufficient for the identification of hypovolemia in patients diagnosed with septic shock.

Postpartum Cardiogenic Shock Diagnosed by Focused Cardiac Ultrasound and Treated With Venoarterial Extracorporeal Membrane Oxygenation: A Case Report

We present the case of a primigravid patient, who developed cardiogenic shock during the early postpartum period in the setting of retained placenta, uterine atony, and hemorrhage. Focused cardiac ultrasound played a central role in identifying the cause of hemodynamic instability. The decision to initiate venoarterial extracorporeal membrane oxygenation was instrumental in the successful outcome for our patient, characterized by a full recovery without major neurological and cardiovascular sequelae.

Remote real-time supervision via tele-ultrasound in focused cardiac ultrasound: A single-blinded cluster randomized controlled trial

BACKGROUND

Supervision via tele-ultrasound presents a remedy for lacking on-site supervision in focused cardiac ultrasound, but knowledge of its impact is largely absent. We aimed to investigate tele-supervised physicians' cine-loop quality compared to that of non-supervised physicians and compared to that of experts.

METHODS

We conducted a single-blinded cluster randomized controlled trial in an emergency department in western Denmark. Physicians with basic ultrasound competence scanned admitted patients twice. The first scan was non-supervised, and the second was non-supervised (control) or tele-supervised (intervention). Finally, experts in focused cardiac ultrasound scanned the same patient. Two blinded observers graded cine-loops recorded from all scans on a 1-5 scale. The outcome was the mean summarized scan gradings compared with a linear mixed-effects model.

RESULTS

In each group, 10 physicians scanned 44 patients. From the mean summarized gradings, on a scale from 4 to 20, the second non-supervised scan grading was 10.9 (95% CI 10.2-11.7), whereas the tele-supervised grading was 12.6 (95% CI: 11.8-13.3). From the first to the second scan, tele-supervised physicians moved 9% (1.09; 95% CI: 1.00-1.19; P = 0.041) closer to the experts' quality than the non-supervised physicians.

CONCLUSION

Tele-supervised physicians performed scans of better quality than non-supervised physicians. The present study supports the use of tele-supervision for physicians with basic focused ultrasound competence in a setting where on-site supervision is unavailable.