spa-aap reviews
Saturday Session V: Ultrasound Review
Reviewed by Iskra Ivanova, MD
Seattle Children’s Hospital
Vascular Access: New Technology and Best Practices
Saturday Session V discussed vascular access - new technologies and best practices, and advanced ultrasound applications in the operating room.
Luis M. Zabala, MD (University of Texas Southwestern Medical Center, Children’s Health) presented the following objectives for the talk:
- Identify variables associated with difficult IV (DIVA) access in children
- List available devices used to assist in obtaining vascular access
- Implement effective practices for successful ultrasound vascular cannulation
Approximately 300 million vascular catheters are placed annually in the U.S. and the literature reports an average 2-4 attempts for cannulation. Vascular access is a source of patient discomfort and significant morbidity.
General conditions associated with DIVA fall under three distinct categories:
- Chronic medical conditions, e.g. patients that have had repeated venipuncture
- Acute medical conditions, e.g. trauma, burns
- Patient specific characteristics, e.g. obesity, pediatric patients
Dr. Zabala pointed out that up to 25% of first attempts fail and 9% require more than four attempts, and subsequent treatment delays.
Can we predict DIVA in children? Dr. Zabala presented a study that described the derivation of a DIVA score as a clinical predictor for identifying children with difficult intravenous access.1
Dr. Zabala continued with an overview of the currently available devices for use in a DIVA situation as well as their respective effectiveness.
- Intraosseous access is a quick and reliable alternative for pediatric patients with prolonged difficult or failed iv access
- Transillumination
- Has a lower risk of first attempt failure versus traditional method
- More effective in a subgroup of patients < age 2
- Relies on light penetration, limiting its use to superficial veins
- Near-Infrared Light technology
- Rapid assessment of viable venous targets and catheter/vein ratio
- Maximum depth of visibility up to 8 mm
- Randomized clinical trial of three devices: VeinViewer, AccuVein AV 300 and VascuLuminator2
- The trial concluded that although visibility is enhanced, NIR devices do not improve cannulation
Dr. Zabala continued with an ultrasound guided vascular access review, starting with the basic principles of ultrasound. He emphasized the importance of using correct terminology, provided tips on positioning, and demonstrated some ultrasound techniques to improve success of cannulation. The gold standard ultrasound technique involves real-time 2D ultrasound and needle visualization throughout the cannulation process. Dr. Zabala presented international evidence-based recommendations on using ultrasound-guided vascular access, based on conference reports and expert panel.3 There is consensus that including ultrasound guidance in the design and conduct of education and training for venous and arterial access should be a strong recommendation. Some new cutting edge ultrasound technologies were presented as well, including ultrasound with electromagnetic guidance, ultrasound with GPS guidance (SonixGPS), and high frequency 70 MHz ultrasound probe.
In conclusion, Dr. Zabala provided the following recommendations:
- Anesthesiologists should recognize and identify children at risk for DIVA
- All anesthesiologist should be proficient in using intraosseous devices
- Real-time ultrasound guidance should be considered when DIVA is encountered and should be used in all central venous insertions
- Anesthesiologists should lead safety and education initiatives, related to efficiency, experience and access to timely intravenous access in the perioperative setting
Advanced Ultrasound Application in the Operating Room
Marc Mecoli, MD (Cincinnati Children’s Hospital Medical Center) presented the following objectives of the talk:
- Emerging applications of the point-of-care ultrasound in the operating room
- Use of ultrasound for preoperative assessment of gastric contents
- Utility of ultrasound for airway evaluation and ETT placement and confirmation in children
- Lung ultrasound for the diagnosis of pneumothorax
- Real-time ultrasound for cardiac evaluation and hemodynamic assessment
Dr. Mecoli started by reviewing the advantages and limitations of point-of-care ultrasound.
- Advantages of point-of-care ultrasound
- Readily available in critical situations
- Real time evaluation
- Limit radiation exposure
- Non-invasive
- Small, portable, improved image quality, decreased cost
- Limitations of point-of-care ultrasound
- Requires skill and training
Next, Dr. Mecoli focused on gastric ultrasonography and anesthetic implications. Increased gastric fluid or solid contents implies a ‘full stomach’. Gastric ultrasonography may have a role in identifying patients at risk for aspiration. Ultrasound provides a qualitative assessment of gastric contents, as well as quantitative measurement of gastric volume. Dr. Mecoli reviewed a research report looking at gastric ultrasound as preoperative bedside test for residual gastric contents volume in children.4 Ultrasound antral cross-sectional area correlated with gastric content volume, and can be used as a potential risk assessment tool (e.g. pyloromyotomy in infants).
Gastric ultrasonography for evaluation of stomach contents has the advantages of being quick, non-invasive qualitative and quantitative assessment that may help predict aspiration risk. It is limited by the need for further validation and prediction models in children.
Dr. Mecoli then moved on to discuss the utility of ultrasound in evaluating the airway, confirming endotracheal tube placement, and verifying ETT depth. He advised using a linear high frequency probe when scanning the airway. Then, briefly presented a study looking at bedside sonography for endotracheal tube placement in pediatric patients and pointing out that ultrasound visualization the ETT through the cricothyroid membrane was 100% accurate and took on average 17 seconds.5 Another study looked at tracheal rapid ultrasound saline test (real-time evaluation of saline-filled cuff at suprasternal notch) for confirming correct endotracheal tube depth in children.6 This proved to be highly sensitive and specific test that took an average of four seconds of ultrasound imaging.
In summary, Dr. Mecoli stated that ultrasound for airway evaluation may be especially useful in low cardiac output states or severe bronchospasm, as well as its potential role in predicting difficult intubation or performing cricothyroidotomy.
Dr. Mecoli then proceeded to discuss the utility of lung ultrasound for detection of pneumothorax. He pointed out that some adult studies report better sensitivity for pneumothorax diagnosis then chest X-ray and similar data in the pediatric population is emerging. He went over normal lung ultrasound anatomy (high frequency probe on anterior chest in sagittal orientation) and the sonographic ‘bat sign”. He then continued on to demonstrate normal ‘lung sliding’ and the lack of when pneumothorax is present, as well as the characteristic ‘barcode sign’ in M-mode ultrasound (as opposed to the ‘seashore sign’ in the normal lung). He briefly presented an article looking at transthoracic lung ultrasound for diagnosing atelectasis in children, which found that lung ultrasound accurately identified anesthesia-induced atelectasis.
The last part of the session zeroed in on ultrasound for cardiac and hemodynamic assessment. Point-of-care echocardiography (including hand-carried ultrasound devices) is an indispensable tool for:
- Rapid detection of pericardial effusion
- Qualitative assessment of LV and RV function
- Determine volume status (IVC variation during positive pressure ventilation)
- Focused perioperative transthoracic cardiac echo
Future directions of the role of ultrasound in pediatric anesthesia focuses on continuing to explore new applications, establishing standardized ultrasound curriculum for pediatric anesthesia trainees, as well as competency milestones and role of certification.
References
- Yen K., Riegert A., Gorelick M. Derivation of the DIVA score. A clinical prediction rule for the identification of children with difficult intravenous access. Pediatric Emergency Care 2008; 24(3):143-7.
- De Graaff J., Cuper N., Mungra R., et al. Near-infrared light to aid peripheral intravenous cannulation in children: a cluster randomized clinical trial of three devices. Anaesthesia 2013; 68(8):835-45.
- Lamperti M., Bodenham A., Pittiruti M., et al. International evidence-based recommendations on ultrasound-guided vascular access. Intensive Care Medicine 2012; 38(7):1105-17.
- Schmitz A., Schmidt A., Buehler P., et al. Gastric ultrasound as a preoperative bedside test for residual gastric contents volume in children. Pediatric Anesthesia 2016; 26(12):1157-64.
- Galicinao J., Bush A., Godambe S. Use of bedside ultrasonography for endotracheal tube placement in pediatric patients: a feasibility study. Pediatrics 2008; 120(6):1297-303.
- Tessaro M., Salant E., Arroyo A., et al. Tracheal rapid ultrasound saline test (T.R.U.S.T.) for confirming correct endotracheal tube depth in children. Resuscitation 2015; 89(4):8-12.
