The aim of this study was to determine the minimum effective volume of lidocaine 1.5% with epinephrine 5 μg/mL in 90% of patients (MEV90) for double-injection ultrasound-guided supraclavicular block (SCB).
Methods:
Using an in-plane technique and a lateral to medial direction, a double-injection ultrasound-guided SCB was performed. A 17-gauge, 8-cm Tuohy needle was initially advanced until its tip was positioned at the intersection of the first rib and subclavian artery ("corner pocket"). Half the volume of lidocaine was injected in this location. Subsequently, the needle was redirected toward the neural cluster formed by the trunks and divisions of the brachial plexus. The remaining volume of lidocaine was deposited in this location. Volume assignment was carried out using a biased coin design up-and-down sequential method, where the total volume of local anesthetic administered to each patient depended on the response of the previous one. In case of failure, the next subject received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous patient had a successful block, the next subject was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 − b = 0.89. Each increment or decrement was evenly distributed between the "corner pocket" (1.25 mL) and neural cluster (1.25 mL). Lidocaine 1.5% with epinephrine 5 μg/mL was used in all subjects. Success was defined, at 30 minutes, as a minimal score of 14 of 16 points using a composite scale encompassing sensory and motor block. Patients undergoing surgery of the elbow, forearm, wrist, or hand were prospectively enrolled until 45 successful blocks were obtained.
Results:
Fifty-four patients were included in the study. Using isotonic regression and bootstrap confidence interval, the MEV90 for double-injection ultrasound-guided SCB was estimated to be 32 mL (95% confidence interval, 30-34 mL). All patients with a minimal composite score of 14 points at 30 minutes achieved surgical anesthesia intraoperatively.
Conclusions:
For double-injection ultrasound-guided SCB, the MEV90 of lidocaine 1.5% with epinephrine 5 μg/mL is 32 mL. Further dose finding studies are required for other concentrations of lidocaine, other local anesthetic agents and single-injection techniques.
We measured the level of contamination in 207 breathing system filters of five different models. The median (IQR [range]) levels of contamination measured in relative light units on the machine side of the filters were: HMEF 750/S 27 (16-56 [4-13 615]); Ultipor BB25 26 (13-40 [9-66]); Humid-vent filter pedi 19 (15-34 [11-48]); Hygroboy 11 (7-19 [3-113]); and Hygrobaby 9 (6-14 [4-21]). A total of 41/138 (30%) of the HMEF 750/S (the most commonly used filter) had measured values > 50, indicating excessive contamination on the machine side of the filter. The incidence of coughing and duration of the case were significantly associated with the incidence of excessive contamination on the machine side (p = 0.034 and p = 0.024, respectively). Excessive contamination on the machine side of the filter could be from the patient or from the re-used breathing system and could result in cross-infection. The level of contamination may need to be checked routinely during each list.
Background: Adenosine triphosphate (ATP) bioluminescence has been used to assess the efficacy and factors that increase the chance of cross‐contamination of HME (heat and moisture exchanging) filters in adults [1, 2]. This method is recommended for testing in hygiene monitoring [3]. The aim was to evaluate the efficacy of breathing system filters and ascertain potential factors responsible for contamination of breathing system used in children. Method: Breathing system filters were collected over 10 days from theatres and swabbed on both the patient and machine sides. The breathing system used in the anaesthetic rooms and theatres were swabbed twice daily. The contamination was assessed using the Bio trace Clean‐Trace ® (3M Health Care Limited, Loughborough, UK). Data collected included age and weight of the patient, type of surgery, duration of use of the HME filter and breathing system, type of airway device and ventilation, position and episodes of cough at induction and extubation. Values of less than 50 relative light units (RLU) were considered as background contamination, >50 RLU as contamination [1]. Values >100 RLU are indicative of contamination in the food industry [3]. Results: One hundred and nineteen breathing system filters (60 Dar Hygroboy ® , 17 Dar Hygrobaby ® , 33 Humid‐Vent ® Filter Pedi, 5 Pall Ultipor ® , 4 HMEF/750 ® ) were tested. The age of the children ranged from 2 days to 15 years (mean 7.4 years). The median [IQR] {range} for duration of use of the filters in minutes were 40 [23–60] {8–330} respectively. On the patient side, the median [IQR] {range} RLU of the filters were 65 (30–125) {5–47006}. A total of 67 (56%) and 40 (34%) of these filters had RLU levels greater than 50 and 100 respectively. On the machine side, the median (IQR) [range] RLU of the filters were 12 (5–45) [2–202]. 27 (23%) and 7 (6%) of these filters had RLU levels greater than 50 and 100 respectively. Six of these seven filters were from patients either second or third on the list. There were mild associations between contamination on the patient and machine sides (Spearman's ρ = 0.26, P = 0.004) and duration and contamination on the patient side (ρ = 0.21, P = 0.022), but not between duration and contamination on the machine side (ρ = −0.02, P = 0.81). At start of the day, the median (IQR) [range] RLU of the breathing systems were 10 (6–30) [1–144]. 3 (12%) and 1 (4%) of these had RLU levels greater than 50 and 100 respectively. At the end of the day, the median [IQR] {range} RLU of the breathing systems were 84 (54–162) [14–331]. 16 (76%) and 8 (38%) of the breathing system had RLU levels greater than 50 and 100 respectively. Ten children (8.4%) coughed, this caused significant higher RLU on the patient side of the filter with median (IQR) [range] being 179 (107–400) [29–492]. However, RLU was 50 or less on the machine side in 90% of these filters. Discussion: HME filters are changed with every case, whereas change of breathing systems is variable from every list to every day to every week. Our results show that a majority of the breathing systems in the operating theatres were contaminated by the end of the day. We suggest using a bioluminescence test before reusing the breathing system for another list. Acknowledgement: 3M Health Care Limited, Loughborough, UK for providing the Biotrace Clean‐Trace ® equipment for this study.
This prospective, randomized, observer-blinded study compared ultrasound guidance and the conventional landmark-based technique for superficial cervical plexus blockade.Forty patients were randomly allocated to receive a block of the superficial cervical plexus using ultrasound guidance (n = 20) or the traditional landmark-based technique (n = 20). The main outcome, success, was defined as the absence of cold sensation for all 4 branches of the superficial cervical plexus at 15 mins. A blinded observer recorded success rate, onset time, block-related pain scores, and the incidence of complications. Performance time and the number of needle passes were also recorded during the performance of the block. Total anesthesia-related time was defined as the sum of performance and onset times.Success rate (80%-85%) was similar between the 2 groups. Performance time was slightly longer with ultrasonography (119 versus 61 sec, P < 0.001); however, no differences in onset and total anesthesia-related times were found. There were also no differences in the number of passes and procedural discomfort.Ultrasound guidance does not increase the success rate of superficial cervical plexus block compared with a landmark-based technique. Additional confirmatory trials are required.
Background In contrast to fluoroscopy, ultrasonography allows visualization of structures such as muscles, tendons, vessels, and nerves. We describe a case where ultrasonography in conjunction with fluoroscopy led to the incidental diagnosis of bowel herniation in a patient undergoing a caudal block. Clinical features A 71-yr-old woman presented to our chronic pain clinic with a long-standing history of coccydynia for which she had undergone a partial coccygectomy. A trial caudal block was planned. Fluoroscopy of the lower sacral area revealed the presence of a gas bubble inferoposteriorly to the coccygeal remnant. A confirmatory ultrasound scan revealed a hollow structure compatible with bowel. The procedure was abandoned. Subsequently, a non-enhanced computed tomographic scan of the pelvis confirmed the diagnosis of large bowel herniation. The patient was referred to a colorectal surgeon, and she subsequently underwent successful laparoscopic repair of the coccygeal hernia. Conclusion Ultrasonography can be a valuable adjunct in identifying non-neural pathologies in patients undergoing interventional procedures in chronic pain management. This case report highlights the importance of being vigilant for unanticipated pathologies during ultrasound examinations while performing chronic pain block procedures.
The aim of this study was to determine the minimum effective volume of lidocaine 1.5% with epinephrine 5 μg/mL in 90% of patients (MEV90) for single-injection ultrasound-guided infraclavicular block (ICB).
Methods:
Using an in-plane technique, a single-injection ultrasound-guided ICB was performed: a 17-gauge, 8-cm Tuohy needle was advanced until the tip was located dorsal to the axillary artery. Volume assignment was carried out using a biased coin design up-and-down sequential method, where the volume of local anesthetic administered to each patient depended on the response of the previous one. In case of failure, the next subject received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous patient had a successful block, the next subject was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 − b = 0.89. Lidocaine 1.5% with epinephrine 5 μg/mL was used in all subjects. Success was defined, at 30 mins, as a minimal score of 14 of 16 points using a composite scale encompassing sensory and motor block. Patients undergoing surgery of the elbow, forearm, wrist, or hand were prospectively enrolled until 45 successful blocks were obtained.
Results:
Fifty-five patients were included in the study. Using isotonic regression and bootstrap confidence interval (CI), the MEV90 for single-injection ultrasound-guided ICB was estimated to be 35 mL (95% CI, 30-37.5 mL). The probability of a successful response at 35 mL was estimated to be 0.91 (95% CI, 0.8-1.0). All patients with a minimal composite score of 14 points at 30 mins achieved surgical anesthesia intraoperatively.
Conclusions:
For single-injection ultrasound-guided ICB, the MEV90 of lidocaine 1.5% with epinephrine 5 μg/mL is 35 mL. Further dose-finding studies are required for other concentrations of lidocaine, other local anesthetic agents as well as techniques involving multiple injections, a more medial approach to ICB, or precise location of all 3 cords of the brachial plexus.
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