The role of ultrasonography in obstetric anesthesia

Complex Pathology and Management in the Obstetric Patient: A Narrative Review for the Anesthesiologist

Pregnant patients may present with multiple complex comorbidities that can affect peripartum management and anesthetic care. The preanesthesia clinic is the ideal setting for early evaluation of high-risk pregnant patients. Comorbidities may include cardiovascular pathology such as valvular abnormalities, septal defects, aortopathies, arrythmias and cardiomyopathies. Additional comorbidities include pulmonary conditions such as obstructive sleep apnea as well as preexisting neuromuscular and skeletal disorders that may impact anesthetic management. Hematologic conditions involving both bleeding diathesis and thrombophilias may present unique challenges for the anesthesiologist. Patients may also present with endocrinopathies including diabetes and obesity. While not as common, high-risk patients may also have preexisting gastrointestinal conditions such as liver dysfunction, renal failure, and even post-transplant status. Ongoing and prior substance abuse, obstetric conditions such as placenta accreta spectrum disorders, and fetal conditions needing ex utero Intrapartum treatment also require advanced planning. Preanesthesia evaluations also help address important ethical and cultural considerations. Counseling patients regarding anesthetic considerations as well as addressing concerns will play a role in reducing racial and ethnic disparities. Anticipatory guidance by means of pre-anesthetic planning can facilitate multidisciplinary communication and planning. This can allow for an impactful and meaningful role in the care provided, allowing for safe maternal care and optimal outcomes.

Ultrasound increases the success rate of spinal needle placement through the epidural needle during combined spinal-epidural anaesthesia: A randomised controlled study

BACKGROUND

Combined spinal-epidural anaesthesia (CSEA) using a needle-through-needle technique is currently widely used. However, successful epidural needle placement does not mean a successful spinal needle placement during CSEA. Whether ultrasound assistance could increase the first-pass success rate of spinal needle placement for CSEA remains unknown.

OBJECTIVE

The aim of this study was to investigate if ultrasound assistance could increase the first-pass success rate of spinal needle placement through the epidural needle during CSEA performed by experienced anaesthesiologists in patients undergoing caesarean section.

DESIGN

A prospective, randomised, double-blind study.

SETTING

Single centre, Department of Anaesthesiology, Shengjing Hospital, China Medical University, China, from June 2019 to September 2019.

PATIENTS

A total of 185 patients (aged 24 years to 52 years, American Society of Anesthesiologists grade (ASA) II-III, 38 to 40 weeks gestation) scheduled to undergo elective caesarean section under CSEA were enrolled.

INTERVENTION

The patients were randomised to either an ultrasound group (patients received a preprocedural ultrasound scan, and the puncture site was identified by ultrasound imaging) and a palpation group (patients received a sham procedural ultrasound scan, and the puncture site was identified by conventional palpation).

MAIN OUTCOME MEASURES

The primary outcome measure was the first-pass success rate for spinal needle placement through the epidural needle. Secondary outcome measures were total duration of CSEA, time required for successful epidural needle and spinal needle placement, number of epidural needle redirections and complications.

RESULTS

Preprocedural ultrasound imaging significantly increased the first-pass success rate of spinal needle placement through the epidural needle compared with conventional palpation (93.8 vs. 68.8%, P < 0.001). Preprocedural ultrasound imaging also decreased the total duration of CSEA (186.9 ± 37.1 vs. 213 ± 60.4 s, P = 0.0015) and the time required for successful spinal needle placement (78.3 ± 22.9 vs. 100.1 ± 53.7 s, P < 0.01) compared with conventional palpation. Fewer patients in the ultrasound group needed epidural needle redirections during the spinal needle placement procedure than in the palpation group (four patients vs. 20 patients, P < 0.01).

CONCLUSION

For experienced anaesthesiologists, preprocedural ultrasound imaging significantly increased the first-pass success rate of spinal needle placement through the epidural needle for obstetric patients undergoing caesarean section under CSEA.

TRIAL REGISTRATION

chictr.org.cn, identifier: ChiCTR1900024132.

Efficacy of electrical stimulation on epidural anesthesia for cesarean section: a randomized controlled trial

Background

Loss of resistance (LOR) technique is a widely used method to identify the epidural space. However, cases of inadequate epidural anesthesia in cesarean section were frequently reported. Also, the success rate of epidural anesthesia with LOR technique varied depending on the proficiency of the practitioner. The purpose of this study was to assess the efficacy and safety of electrical stimulation to identify epidural spaces in cesarean section for novices or clinicians with recent gap in experience.

Methods

Pregnant women scheduled for elective cesarean section were randomly allocated to two groups. Groups were classified based on the methods used for identifying the epidural space: the LOR group (group L) and the LOR with epidural electrical stimulation group (group E). Clinicians with less than 10 epidural cesarean section experiences in the recent year performed epidural anesthesia for cesarean section. In the group E, a RegionalStim® conductive catheter was inserted through the Tuohy needle, and the guidewire passing through the catheter was connected to a peripheral nerve stimulator. The intensity of the stimulation was gradually increased from 0.25 mA to 1.5 mA until paresthesia was elicited and radiated. We assessed the success of epidural anesthesia (complete success, partial success or failure). Other clinical parameters including maternal satisfaction, time required for epidural anesthesia, neonatal Apgar scores, pain scores and adverse events were compared between the two groups.

Results

Except for 6 patients who withdrew consent, 54 patients were enrolled in this study (28 for the group L and 26 for the group E). The demographic data showed no difference between the two groups. There was no adverse event resulted from electrical stimulation. The group E showed higher rate of complete success, sensitivity in finding epidural space and maternal satisfaction compared to the group L (21/26 vs. 15/28, p = 0.034, 0.96 vs. 0.68, p = 0.012 and 4.04 vs. 3.39, p = 0.02, respectively). The other clinical parameters showed no differences between the two groups.

Conclusion

In addition to the conventional LOR technique, identifying epidural spaces using electrical stimulation led to better outcomes without additional risks for novices as well as clinicians with recent gap in experience.

Trial registration

This study was retrospectively registered in the ClinicalTrials.gov Registry (NCT03443466) on February 23, 2018.

Thoracic ultrasound evaluation and B-type natriuretic peptide value in elective cesarean section under spinal anesthesia

Background

Pregnancy-induced changes in cardiovascular status make women more susceptible to pulmonary edema. During cesarean section, to counterbalance the effect of hypotension caused by spinal anesthesia, anesthesiologists must choose between two fundamental approaches to maintain the hemodynamic state—intravenous fluids or vasopressors—and this choice will depend upon their particular opinions and experience. We aim to assess for any correlations between thoracic ultrasound A- and B-line artifacts, brain natriuretic peptide (BNP) levels, and the amount of intraoperative fluids administered.

Results

From December 2016 to August 2018, at the University-Hospital of Udine, we enrolled 80 consecutive pregnant women undergoing cesarean section. We observed a statistically significant difference in the volume of fluids administered in the first 24 h (p = 0.035) between the patients presenting B-lines in at least one basal area of their thoracic ultrasound and patients with no evident B-lines (AUC 66.4%; IC 0.49–0.83). Dividing the population on whether their BNP levels were higher or less than 20 pg/mL, no statistically significant difference was revealed with regard to fluids administered in the first 24 h (p = 0.537).

Conclusions

Thoracic ultrasound is a non-invasive and easy-to-use tool for detecting fluid intolerance in pregnant women undergoing cesarean section. BNP levels were slow to rise following the cesarean section and did not show any clear correlation with fluid volumes administered.

Abnormal lung ultrasound pattern during labor: A prospective cohort pilot study

PURPOSE

Lung ultrasound (LUS) examination is used to evaluate patients with acute respiratory failure. The physiological LUS pattern during labor in healthy parturients has not been well described. The aim of this study was to evaluate the LUS pattern in a cohort of healthy women during uncomplicated labor.

METHODS

We used the 8-point LUS assessment protocol and investigated lung sliding, A-lines, B-lines, interstitial syndrome, lung consolidation, and pleural effusion according to the International Consensus Document with two additional supradiaphragmatic projections. All patients were screened twice; once during the first stage of labor and again within 2 hours after delivery.

RESULTS

We included 24 patients in this study from February 2014 to August 2015. A total of 480 LUS records were retained for further analysis. Overall, 16 of 24 patients (67%) had at least one positive region (three or more B-lines) during the peridelivery LUS evaluation. Interstitial syndrome was detected in five patients (21%). There were no differences in A-line (P = 0.38) or B-line (P = 0.68) prevalence between LUS examinations before and after delivery.

CONCLUSIONS

Women in uncomplicated labor can present abnormal LUS findings, which may affect the interpretation of LUS results in patients with respiratory deterioration. Further studies should address this topic in larger cohort of patients.