Intra- and interrater reliability of ultrasound assessment of gastric volume.

BACKGROUND: Gastric sonography can provide information about gastric content and volume that can help determine aspiration risk at the bedside. The primary objective of this study is to assess the intrarater and interrater reliability of a previously validated method of gastric volume assessment based on gastric antral area. The secondary objective is to evaluate the agreement between two different methods to measure gastric antral area. METHODS: Three independent raters performed a standardized gastric ultrasound assessment in healthy subjects who had been randomly allocated to ingest a predetermined volume of clear fluid (apple juice) from 0 to 400 ml. Each rater measured the gastric antral area, using twice the two-diameter method and twice the free-tracing method. The rater order was allocated at random and raters were unaware of the volume ingested and of one-another's measurements. The Guidelines for Reporting Reliability and Agreement Studies were followed for conducting and reporting this study. RESULTS: Twenty-two volunteers were studied. Ultrasound assessment of antral cross-sectional area and volume was found to have "nearly perfect" intrarater and interrater reliability (correlation coefficient >0.8) with maximum differences within 13%. A Bland-Altman analysis suggests that the free-tracing method and the two-diameter method are essentially equivalent, within a clinically acceptable level of agreement. CONCLUSIONS: Ultrasound assessment of gastric volume by clinical anesthesiologists is highly reproducible with high intrarater and interrater reliability. The free-tracing method to measure antral cross-sectional area is equivalent to the two-diameter method.

The impact of analgesic modality on early ambulation following total knee arthroplasty.

INTRODUCTION: Total knee arthroplasty is associated with moderate to severe pain, and effective analgesia is essential to facilitate postoperative recovery. This retrospective cohort study examined the analgesic and rehabilitation outcomes associated with 48-hour continuous femoral nerve block, local infiltration analgesia, or local infiltration analgesia plus adductor canal nerve block. METHODS: Patients undergoing total knee arthroplasty under spinal anesthesia, during an 8-month period, were retrospectively assessed with a targeted review of 100 patients per group. Records of eligible patients were reviewed to identify the analgesic technique used and the primary outcome of distance walked on postoperative day 1. Secondary outcomes included ambulation on days 2 and 3, numeric rating scale pain scores, opioid consumption, and adverse effects and discharge disposition. RESULTS: Two hundred ninety-eight eligible patients were reviewed. Local infiltration analgesia and local infiltration plus adductor canal block were associated with longer distances walked on postoperative day 1 than continuous femoral nerve block (median values of 20, 30, and 0 m, respectively; P < 0.0001). The addition of adductor canal block was associated with further improvement in early ambulation benchmarks and a higher rate of home discharge compared with only local infiltration (88.2% vs 73.2%, P = 0.018). Local infiltration with or without adductor canal block was associated with lower pain scores at rest and during movement for the first 24 hours and lower opioid consumption than continuous femoral nerve infusion. CONCLUSIONS: Local infiltration analgesia was associated with improved early analgesia and ambulation. The addition of adductor canal nerve block was associated with further improvements in early ambulation and a higher incidence of home discharge.

Ultrasound-guided popliteal block through a common paraneural sheath versus conventional injection: a prospective, randomized, double-blind study.

BACKGROUND AND OBJECTIVES: The macroscopic anatomy of a common paraneural sheath that surrounds the sciatic nerve in the popliteal fossa has been studied recently in a human cadaveric study. It has been suggested that an injection through this sheath could be an ideal location for local anesthetic administration for popliteal block. The aim of the present study was to evaluate the hypothesis that popliteal sciatic nerve blockade through a common paraneural sheath results in shorter onset time when compared with conventional postbifurcation injection external to the paraneural tissue. To illustrate the microscopic anatomy of the paraneural tissues, we performed histological examinations of a human leg specimen. METHODS: Following institutional review board approval and written informed consent, 89 patients undergoing an ultrasound-guided popliteal block for foot or ankle surgery were included in the study. They were prospectively randomized to receive a single injection of local anesthetic at the site of bifurcation through a common paraneural sheath (group 1) or 2 separate circumferential injections of the tibial and common peroneal nerves distally to sciatic nerve bifurcation (group 2). RESULTS: Patients in group 1 had a 30% shorter onset time of both sensory and motor block. This was associated with a more extensive proximal and distal longitudinal spread of local anesthetic in this group. Nerve diameter and cross-sectional area remained unchanged in both groups after injection, which is consistent with extraneural injection. A greater proportion of patients in group 1 required a single needle pass for block performance. DISCUSSION: An ultrasound-guided popliteal sciatic nerve block through a common paraneural sheath at the site of sciatic nerve bifurcation is a simple, safe, and highly effective block technique. It results in consistently short onset time, while respecting the integrity of the epineurium and intraneural structures.

Bedside ultrasound assessment of gastric content: an observational study.

PURPOSE: There is a growing interest in the use of bedside ultrasonography to assess gastric content and volume. It has been suggested that the gastric antrum in particular can be assessed reliably by sonography. The aim of this observational study was to provide a qualitative description of the sonographic characteristics of the gastric antrum when the stomach is empty and following the ingestion of clear fluid, milk, and solid content. CLINICAL FEATURES: Six healthy volunteers were examined on four different occasions (24 scanning sessions): following a period of eight hours of fast and following ingestion of 200 mL of apple juice, 200 mL of 2% milk, and a standard solid meal (sandwich and apple juice). Examinations were performed following a standardized scanning protocol by two clinical anesthesiologists with previous experience in gastric sonography. For each type of gastric content, the sonographic characteristics of the antrum and its content are described and illustrated with figures. CONCLUSIONS: Bedside sonography can determine the nature of gastric content (nil, clear fluid, thick fluid/solid). This qualitative information by itself may be useful to assess risk of aspiration, particularly in situations when prandial status is unknown or uncertain.

Hand motion analysis using the imperial college surgical assessment device: validation of a novel and objective performance measure in ultrasound-guided peripheral nerve blockade.

BACKGROUND AND OBJECTIVES: The Imperial College Surgical Assessment Device (ICSAD) has been validated in various settings as an objective tool to measure technical performance. We sought to establish (1) the construct validity of the ICSAD as an assessment tool in ultrasound-guided supraclavicular block by determining its ability to discriminate between operators of different experience level and (2) the concurrent validity of the ICSAD by correlating it with a task-specific checklist and a global rating scale. METHODS: We compared 30 performances of ultrasound-guided supraclavicular block by junior residents with 30 performances by highly experienced consultant anesthesiologists. We also studied 10 anesthesiologists undertaking a 1-year regional anesthesia fellowship and compared a performance in their first month to one in their last 3 months. We used the ICSAD to measure 3 dexterity parameters during the scanning and needling phases of each block: time taken, number of movements, and path length traveled by each hand. Two blinded expert observers evaluated video recordings of each block using a 30-item task-specific checklist and a 7-item global rating scale. RESULTS: Consultants (experts) performed significantly better than residents (novices) on all ICSAD parameters in both scanning and needling phases. Fellows demonstrated improvement in all ICSAD parameters between their early and late performance, reflecting their transition from novice to expert. The task-specific checklist and global rating scale were also highly discriminating between novice and expert performances. There was excellent correlation between all 3 measurement tools, thereby establishing their concurrent validity. CONCLUSIONS: The ICSAD is both valid and useful in assessing performance of ultrasound-guided supraclavicular block.

Practical knobology for ultrasound-guided regional anesthesia.

This article provides an instructive review of the essential functions universal to modern ultrasound machines in use for regional anesthesia practice. An understanding of machine knobology is integral to performing safe and successful ultrasound-guided regional anesthesia.