Non-pyrogenicity and biocompatibility of parylene-coated magnetic bead implants.

Clinical grade magnetic bead implants have important applications in interfacing with the human body, providing contactless mechanical attachment or wireless communication through human tissue. We recently developed a new strategy, magnetomicrometry, that uses magnetic bead implants as passive communication devices to wirelessly sense muscle tissue lengths. We manufactured clinical-grade magnetic bead implants and verified their biocompatibility via intramuscular implantation, cytotoxicity, sensitization, and intracutaneous irritation testing. In this work, we test the pyrogenicity of the magnetic bead implants via a lagomorph model, and we test the biocompatibility of the magnetic bead implants via a full chemical characterization and toxicological risk assessment. Further, we test the cleaning, sterilization, and dry time of the devices that are used to deploy these magnetic bead implants. We find that the magnetic bead implants are non-pyrogenic and biocompatible, with the insertion device determined to be safe to clean, sterilize, and dry in a healthcare setting. These results provide confidence for the safe use of these magnetic bead implants in humans.

Anesthesia and Analgesia for the Obese Parturient.

Obesity is a worldwide epidemic and is associated with an increased risk of hypertension, diabetes, and obstructive sleep apnea. Pregnant patients with obesity experience a higher risk of maternal and fetal complications. Anesthesia also poses higher risks for obese parturients and may be more technically challenging due to body habitus. Safe anesthesia practice for these patients must take into consideration the unique challenges associated with the combination of pregnancy and obesity.

Untethered muscle tracking using magnetomicrometry.

Muscle tissue drives nearly all movement in the animal kingdom, providing power, mobility, and dexterity. Technologies for measuring muscle tissue motion, such as sonomicrometry, fluoromicrometry, and ultrasound, have significantly advanced our understanding of biomechanics. Yet, the field lacks the ability to monitor muscle tissue motion for animal behavior outside the lab. Towards addressing this issue, we previously introduced magnetomicrometry, a method that uses magnetic beads to wirelessly monitor muscle tissue length changes, and we validated magnetomicrometry via tightly-controlled in situ testing. In this study we validate the accuracy of magnetomicrometry against fluoromicrometry during untethered running in an in vivo turkey model. We demonstrate real-time muscle tissue length tracking of the freely-moving turkeys executing various motor activities, including ramp ascent and descent, vertical ascent and descent, and free roaming movement. Given the demonstrated capacity of magnetomicrometry to track muscle movement in untethered animals, we feel that this technique will enable new scientific explorations and an improved understanding of muscle function.

Clinical viability of magnetic bead implants in muscle.

Human movement is accomplished through muscle contraction, yet there does not exist a portable system capable of monitoring muscle length changes in real time. To address this limitation, we previously introduced magnetomicrometry, a minimally-invasive tracking technique comprising two implanted magnetic beads in muscle and a magnetic field sensor array positioned on the body's surface adjacent the implanted beads. The implant system comprises a pair of spherical magnetic beads, each with a first coating of nickel-copper-nickel and an outer coating of Parylene C. In parallel work, we demonstrate submillimeter accuracy of magnetic bead tracking for muscle contractions in an untethered freely-roaming avian model. Here, we address the clinical viability of magnetomicrometry. Using a specialized device to insert magnetic beads into muscle in avian and lagomorph models, we collect data to assess gait metrics, bead migration, and bead biocompatibility. For these animal models, we find no gait differences post-versus pre-implantation, and bead migration towards one another within muscle does not occur for initial bead separation distances greater than 3 cm. Further, using extensive biocompatibility testing, the implants are shown to be non-irritant, non-cytotoxic, non-allergenic, and non-irritating. Our cumulative results lend support for the viability of these magnetic bead implants for implantation in human muscle. We thus anticipate their imminent use in human-machine interfaces, such as in control of prostheses and exoskeletons and in closed-loop neuroprosthetics to aid recovery from neurological disorders.

Uterine exteriorization versus in situ repair in Cesarean delivery: a systematic review and meta-analysis.

PURPOSE: We conducted an updated systematic review and meta-analysis on maternal outcomes associated with uterine exteriorization compared with in situ repair in women undergoing Cesarean delivery. METHODS: We searched for randomized controlled trials comparing uterine exteriorization with in situ repair during Cesarean delivery. Primary outcomes were intraoperative nausea and vomiting (IONV) and perioperative decrease in hemoglobin concentration. Secondary outcomes were postoperative nausea and vomiting (PONV), estimated blood loss, fever, endometritis, wound infection, intraoperative and postoperative pain, postoperative analgesic use, duration of surgery and hospital stay, and time to return of bowel function. RESULTS: Twenty studies with 20,909 parturients were included. Exteriorization was associated with higher risk of IONV (odds ratio [OR], 2.09; 95% confidence interval [CI], 1.66 to 2.63; I2 = 0%), with no difference in perioperative hemoglobin concentration decrease (mean difference, - 0.06 g·dL-1; 95% CI, - 0.20 to 0.08; I2 = 97%) compared with in situ repair. There were no significant differences in estimated blood loss, transfusion requirement, PONV, duration of surgery, duration of hospital stay, time to return of bowel function, fever, endometritis, or wound infection. Postoperative pain (incidence of pain graded > 5/10) at six hours (OR, 1.64; 95% CI, 1.31 to 2.03; I2 = 0%) was higher with exteriorization, but there was no difference in need for rescue analgesia (OR, 2.48; 95% CI, 0.89 to 6.90; I2 = 94%) or pain scores at 24 hr compared with in situ repair. CONCLUSIONS: In this updated systematic review and meta-analysis, uterine exteriorization was associated with an increased risk of IONV but no significant change in perioperative hemoglobin decrease compared with in situ repair. STUDY REGISTRATION: PROSPERO (CRD42020190074); registered 5 July 2020.

RéSUMé: OBJECTIF: Nous avons réalisé une mise à jour d'une revue systématique et une méta-analyse portant sur les issues maternelles associées à l'extériorisation de l'utérus par rapport à une réparation in situ chez les femmes accouchant par césarienne. MéTHODE: Nous avons recherché des études randomisées contrôlées comparant l'extériorisation de l'utérus à la réparation in situ pendant un accouchement par césarienne. Les critères d'évaluation principaux étaient les nausées et vomissements peropératoires (NVPerO) et la réduction périopératoire de l'hémoglobine. Les critères d'évaluation secondaires étaient les nausées et vomissements postopératoires (NVPO), la perte de sang estimée, la fièvre, l'endométrite, l'infection de la plaie, la douleur per- et postopératoire, l'utilisation d'analgésiques postopératoires, la durée de la chirurgie et du séjour à l'hôpital, et le délai jusqu'au retour du transit. RéSULTATS: Vingt études portant sur 20 909 parturientes ont été incluses. L'extériorisation était associée à un risque plus élevé de NVPerO (rapport de cotes [RC], 2,09; intervalle de confiance à 95 % [IC], 1,66 à 2,63; I2 = 0 %), sans différence dans la réduction de l'hémoglobine périopératoire (différence moyenne, − 0,06 g·dL-1; IC 95 %, − 0,20 à 0,08; I2 = 97 %) par rapport à une réparation in situ. Il n'y avait pas de différences significatives dans la perte de sang estimée, les besoins transfusionnels, les NVPO, la durée de la chirurgie, la durée du séjour à l'hôpital, le délai jusqu'au retour du transit, la fièvre, l'endométrite ou l'infection de la plaie. La douleur postopératoire (incidence de la douleur graduée > 5/10) à six heures (RC, 1,64; IC 95 %, 1,31 à 2,03; I2 = 0 %) était plus élevée avec une extériorisation, mais il n'y avait aucune différence dans les besoins d'analgésie de secours (RC, 2,48; IC 95 %, 0,89 à 6,90; I2 = 94 %) ou les scores de douleur à 24 heures par rapport à une réparation in situ. CONCLUSION: Dans cette revue systématique et méta-analyse mises à jour, l'extériorisation utérine était associée à un risque accru de NVPerO, mais à aucun changement significatif dans la réduction de l'hémoglobine périopératoire par rapport à la réparation in situ. ENREGISTREMENT DE L'éTUDE: PROSPERO (CRD42020190074); enregistrée le 5 juillet 2020.

Obesity And Obstetric Anesthesia: Current Insights.

Obesity is a significant global health problem. It results in a higher incidence of complications for pregnant women and their neonates. Cesarean deliveries are more common in obese parturients as well. The increased burden of comorbidities seen in this population, such as obstructive sleep apnea, necessitates antepartum anesthetic consultation. These patients pose unique challenges for the practicing anesthesiologist and may benefit from optimization prior to delivery. Complications from anesthesia and overall morbidity and mortality are higher in this population. Neuraxial anesthesia can be challenging to place in the obese parturient, but is the preferred anesthetic for cesarean delivery to avoid airway manipulation, minimize aspiration risk, prevent fetal exposure to volatile anesthetic, and decrease risk of post-partum hemorrhage from volatile anesthetic exposure. Monitoring and positioning of these patients for surgery may pose specific challenges. Functional labor epidural catheters can be topped up to provide conditions suitable for surgery. In the absence of a working epidural catheter, a combined spinal epidural anesthetic is often the technique of choice due to relative ease of placement versus a single shot spinal technique as well as the ability to extend the anesthetic through the epidural portion. For cesarean delivery with a vertical supraumbilical skin incision, a two-catheter technique may be beneficial. Concern for thromboembolism necessitates early mobilization and a multimodal analgesic regimen can help accomplish this. In addition, thromboprophylaxis is recommended in this population after delivery-especially cesarean delivery. These patients also need close monitoring in the post-partum period when they are at increased risk for several complications.