Development of a novel intra-abdominal pressure transducer for large scale clinical studies.

Intra-abdominal pressure may be one of the few modifiable risk factors associated with developing a pelvic floor disorder. With one in eight women having surgery to correct a pelvic floor disorder in their lifetimes, intra-abdominal pressure may be a key to understanding the disease etiology and how to mitigate its occurrence and progression. Many traditional methods of intra-abdominal pressure measurement have limitations in data quality, environment of use, and patient comfort. We have modified a previously reported intravaginal pressure transducer that has been shown to overcome other intra-abdominal pressure measurement technique limitations (Coleman et al. 2012). Our modifications to the intravaginal pressure transducer make it easier to use, less costly, and more reliable than previous designs, while maintaining accuracy, integrity, and quality of data. This device has been used in over 400 participants to date as part of one of the most comprehensive studies examining the relationship between intra-abdominal pressure and pelvic floor disorders.

A ropivacaine-eluting poly(lactide-co-caprolactone) wound dressing provided enhanced analgesia in partial-thickness porcine injuries.

BACKGROUND: Partial-thickness skin wounds are some of the most painful injuries due to large areas of exposed nerve endings. These injuries often require systemic opioid treatments to manage pain adequately. However, in 2021 alone, the CDC reported nearly 17,000 prescription opioid-related deaths in the USA, highlighting the ongoing need for non-opioid treatment strategies. In this manuscript, we developed a novel single-application ropivacaine-eluting primary wound dressing that could provide sustained ropivacaine delivery to partial-thickness wounds and assessed its in vivo feasibility for prolonged non-opioid analgesia. METHODS: Sustained release of ropivacaine from a poly(lactide-co-e-caprolactone) matrix was first optimized in vitro using dissolution testing and a Box Behnken design of experiments. The optimized dressing was then tested against a clinical control silicone dressing in a porcine partial-thickness wound study to assess analgesic effect, pharmacokinetics, and wound healing. RESULTS: The ropivacaine-eluting dressing showed a moderate analgesic effect in vivo, where normalized single pinprick scores significantly improved pain over the testing period (4-168h) (control vs treatment: 232±25% vs 145±16%, p<0.0003). Ropivacaine blood plasma levels peaked at 8 hours post-treatment, with a maximum concentration of 246 ± 74 ng/mL. No significant differences in wound healing were found when compared to control. CONCLUSION: The ropivacaine-loaded poly(lactide-co-e-caprolactone)-based wound dressing provided sustained delivery of ropivacaine to partial-thickness skin wounds and enhanced analgesic effect compared to a clinical standard control dressing.

Intrinsic factors contributing to elevated intra-abdominal pressure.

Pelvic floor disorders affect 24% of US women, and elevated intra-abdominal pressure may cause pelvic injury through musculoskeletal strain. Activity restrictions meant to reduce pelvic strain after traumatic events, such as childbirth, have shown little benefit to patients. Reported high variability in abdominal pressure suggests that technique plays a substantial role in pressure generation. Understanding these techniques could inform evidence-based recommendations for protective pelvic care. We hypothesized use of a motion-capture methodology could identify four major contributors to elevated pressure: gravity, acceleration, abdominal muscle contraction, and respiration. Twelve women completed nineteen activities while instrumented for whole body motion capture, abdominal pressure, hip acceleration, and respiration volume. Correlation and partial least squares regression were utilized to determine primary technique factors that increase abdominal pressure. The partial least squares model identified two principal components that explained 59.63% of relative intra-abdominal pressure variability. The first component was primarily loaded by hip acceleration and relative respiration volume, and the second component was primarily loaded by flexion moments of the abdomen and thorax. While reducing abdominal muscle use has been a primary strategy in protective pelvic floor care, the influence of hip acceleration and breathing patterns should be considered with similar importance in future work.

Assessment of glyceride-structured oleogels as an injectable extended-release delivery system of bupivacaine.

This manuscript systematically assesses three different glycerides (tripalmitin, glyceryl monostearate, and a blend of mono-, di- and triesters of palmitic and stearic acids (Geleol™)) as potential gelator structuring agents of medium-chain triglyceride oil to form an oleogel-based injectable long-acting local anesthetic formulation for postoperative pain management. Drug release testing, oil-binding capacity, injection forces, x-ray diffraction, differential scanning calorimetry, and rheological testing were serially performed to characterize the functional properties of each oleogel. After benchtop assessment, the superior bupivacaine-loaded oleogel formulation was compared to bupivacaine HCl, liposomal bupivacaine, and bupivacaine-loaded medium-chain triglyceride oil in a rat sciatic nerve block model to assess in vivo long-acting local anesthetic performance. In vitro drug release kinetics were similar for all formulations, indicating that drug release rate is primarily dependent on the drug's affinity to the base oil. Glyceryl monostearate-based formulations had superior shelf-life and thermal stability. The glyceryl monostearate oleogel formulation was selected for in vivo evaluation. It was found to have a significantly longer duration of anesthetic effect than liposomal bupivacaine and was able to provide anesthesia twice as long as the equipotent bupivacaine-loaded medium-chain triglyceride oil, indicating that the increased viscosity of the oleogel provided enhanced controlled release over the drug-loaded oil alone.

Pelvic floor tissue damping during running using an intra-vaginal accelerometry approach.

BACKGROUND: While cumulative loading of the pelvic floor during exercise appears to increase the risk of developing pelvic floor disorders, the pathophysiologic role of pelvic floor loading is poorly understood. The aim of this exploratory study was to present a method for evaluating vibrational frequency damping of the female pelvic floor and to investigate the potential utility of this approach in a preliminary evaluation. METHODS: Female participants were instrumented with an intravaginal accelerometer and a hip-mounted accelerometer, then ran on a treadmill at 7 km/h and 10 km/h both before and after a 30-min self-selected pace. Displacement of the pelvic floor relative to the bony pelvis was calculated using double integration of the accelerometer data. Vibrational damping coefficients were calculated using a wavelet-based approach to determine the effect of continence status, parity, running speed and time on vibrational damping. FINDINGS: Seventeen women (n = 10 reported regularly leaking urine while exercising, while n = 7 reported not leaking) completed the running protocol. No differences in vibrational damping were detected between continent and incontinent women when all frequency bands were evaluated together, however significant effects of parity, time, running speed and continence status were found within specific frequency bands. Parous women demonstrated less damping in the 25-40 Hz band compared to nulliparae, damping in the 13-16 Hz band was lower after the 30-min run, and incontinent women demonstrated lower damping in the 4.5-5.5 Hz band than continent women when running at 7 km/h. INTERPRETATION: Intra-vaginal vibrational damping may be useful in detecting biomechanical mechanisms associated with pelvic floor disorders experienced by females during exercise.

Relative and Maximal Intra-abdominal Pressure and Postpartum Pelvic Floor Outcomes in Primiparas Delivered Vaginally.

OBJECTIVES: This study aimed to explore associations between relative and maximal intra-abdominal pressure (IAP) on pelvic floor outcomes in primiparas delivered vaginally. METHODS: At 5-10 weeks and 1 year postpartum, we measured absolute IAP by vaginal sensor while participants lifted a weighted car seat (IAPLIFT) and performed isometric trunk flexion endurance (IAPTFE) and seated maximal strain (IAPSTRAIN). Primary outcomes, completed 1 year postpartum, included worse pelvic floor support (descent to or beyond the hymen) and positive symptom burden (bothersome symptoms in ≥2 of 6 domains on the Epidemiology of Prolapse and Incontinence Questionnaire). We calculated relative IAP (as absolute IAP/IAPSTRAIN). RESULTS: Of 542 participants, 9.7% demonstrated worse support and 54.3% demonstrated symptom burden at 1 year postpartum. In multivariable analyses, absolute IAPLIFT and absolute IAPTFE at 5-10 weeks postpartum were not associated with worse support. As relative IAP at 5-10 weeks increased, the prevalence of worse support decreased (prevalence ratio [PR] of 0.77 [95% confidence intervals (CIs), 0.63-0.94] and PR of 0.79 [95% CI, 0.67-0.93]) per 10% increase for relative IAPLIFT and relative IAPTFE, respectively. This was largely due to IAPSTRAIN, which increased the prevalence of worse support (PR, 1.15 [95% CI, 1.06-1.25]) per 10 cm H2O increase. One year postpartum, only IAPSTRAIN increased the prevalence of worse support (PR, 1.11 [95% CI, 1.02-1.20]) per 10 cm H2O. Of all IAP measures at both time points, only absolute IAPLIFT at 1 year significantly increased the prevalence of symptom burden (PR, 1.11 [95% CI, 1.05-1.18]) per 10 cm H2O. CONCLUSIONS: This exploratory analysis suggests that postpartum IAPSTRAIN may increase the prevalence of worse support in primiparas delivered vaginally.

Temporal trends in trunk flexor endurance and intra-abdominal pressure in postpartum women.

Objectives: To describe change in trunk flexor endurance and intra-abdominal pressure (IAP) associated with trunk flexor assessment and explore factors associated with change in trunk flexor endurance during the first postpartum year.Design: Ancillary analysis of an ongoing prospective cohort study.Methods: Participants (N = 282) were primiparous women delivered vaginally. They completed trunk flexor endurance testing while assessing IAP, body habitus measures (body mass index, waist circumference, and body composition), and questionnaires 5-10 weeks and 11-15 months postpartum. We investigated change in trunk flexor endurance by quartile of improvement and factors associated with improvement (Q4 vs. Q1-Q3) using multivariable models, adjusted for baseline endurance.Results: Mean age was 28 ± 5 years. The median (IQR) trunk flexor hold time increased from early to late postpartum (129/IQR = 68, 217 vs 148/IQR = 80, 265 seconds, p = .01) and mean (SD) IAP decreased (55/SD = 13 vs 48/SD = 14 cmH20, p < .0001). The most improved group (Q4) increased endurance time by 176 seconds (95% CI = 103, 254), were less likely to be Hispanic, more likely to be older, more educated, and have lower measures of body habitus than women in Q1-Q3. Conclusion: Trunk flexor endurance increased and IAP decreased over one year postpartum. Lower body habitus and higher age early postpartum predicted greatest improvement in trunk flexor endurance at 1 year.

Association Between Measures of Trunk Recovery 5 to 10 Weeks Postpartum and Pelvic Floor Support and Symptoms 1 Year Postpartum in Primiparas Delivered Vaginally.

OBJECTIVE: To determine whether 2 aspects of trunk recovery after childbirth, intraabdominal pressure (IAP) generation and trunk flexor endurance (TFE), predict measures of pelvic floor health 1 year postpartum. METHODS: In this prospective cohort study, we enrolled nulliparas in their third trimester and followed up those delivered vaginally for 1 year. We measured IAP while lifting a weighted car seat (IAPLIFT), IAP during TFE testing (IAPTFE), and TFE duration 5 to 10 weeks postpartum and assessed pelvic floor support and symptoms 1 year postpartum. RESULTS: Mean age of the 624 participants was 28.7 years. At 5 to 10 weeks postpartum, mean (SD) maximal IAPLIFT and IAPTFE were 47.67 (11.13) and 51.57 (12.34) cm H2O, respectively. Median TFE duration was 126 seconds (Interquartile range, 74-211). At 1 year postpartum, 9.3% demonstrated worse support (maximal vaginal descent at or below hymen) and 54% met criteria for symptom burden (bothersome symptoms in ≥2 domains of Epidemiology of Prolapse and Incontinence Questionnaire). In multivariable models, neither IAPLIFT nor IAPTFE were associated with worse support or symptom burden (P = 0.54-1.00). Trunk flexor endurance duration increased prevalence of worse support (prevalence ratio, 1.05; 95% confidence interval, 1.01-1.08) per 60-second increase, P = 0.005) but not symptom burden (prevalence ratio, 1.00; 95% confidence interval, 0.98-1.03; P = 0.92). CONCLUSIONS: These results provide some reassurance to early postpartum women, who are unlikely to perform routine activities that generate IAP far outside the range tested. Further research is needed to understand why women with long TFE durations have increased prevalence of worse support.

Do Measures of Muscular Fitness Modify the Effect of Intra-abdominal Pressure on Pelvic Floor Support in Postpartum Women?

OBJECTIVE: This study aimed to determine whether measures of muscular fitness modify the effect of intra-abdominal pressure (IAP) during lifting on pelvic floor support. METHODS: Participants, primiparous women 1 year after vaginal delivery, underwent the Pelvic Organ Prolapse Quantification examination, measurement of IAP via a vaginal sensor while lifting a weighted car seat, pelvic floor muscle force assessment using an instrumented speculum, grip strength using a hand dynamometer, and trunk flexor endurance by holding an isometric contraction while maintaining a 60-degree angle to the table. We dichotomized pelvic floor support as worse (greatest descent of the anterior, posterior, or apical vagina during maximal strain at or below the hymen) versus better (all points above the hymen). RESULTS: Of 825 participants eligible after delivery, 593 (71.9%) completed a 1-year study visit. Mean (SD) age was 29.6 (5.0) years. One year postpartum, 55 (9.3%) demonstrated worse support. There were no differences in IAP during lifting or in other measures of pelvic floor loading between women with better and worse support. In multivariable analyses, neither grip strength nor pelvic floor muscle force modified the effect of IAP on support. In women with trunk flexor endurance duration ≥13 minutes, the odds of worse support increased significantly as IAP increased. No fitness measure modified the effect of other measures of pelvic floor loading on support. CONCLUSIONS: Primiparous women with higher IAP during lifting and greater muscular fitness did not have reduced odds of worse pelvic floor support compared with those with lower IAP at the same muscular fitness.

Subsequent Use of a Pressure Sensor to Record Intra-Abdominal Pressure After Maximum Vaginal Closure Force in a Clinical Trial.

Pelvic floor disorders are caused by weakening or damage to the tissues lining the bottom of the abdominal cavity. These disorders affect nearly 1 in every 4 women in the United States and symptoms that drastically diminish a patient's quality of life. Vaginal closure force is a good measure of pelvic health, but current vaginal dynamometers were not designed for the rigors of hospital reprocessing, often failing due to sensor degradation through repeated sterilization processes. In order to obtain measurements of vaginal closure force in a large study, we designed a vaginal dynamometer that utilizes a removable intra-abdominal sensor already in production for the study. The sensor's existing data acquisition system was modified to transmit to a tablet allowing the user to view data in real-time. The new speculum design allowed a single sensor to measure vaginal closure force before being used to collect intra-abdominal pressure data in the same study visit. The measurements taken with the new speculum were similar to measurements taken with a previously reported vaginal dynamometer.

The Association Between Pelvic Floor Muscle Force and General Strength and Fitness in Postpartum Women.

OBJECTIVE: The aim of the study was to determine whether measures of muscular strength and fitness are associated with pelvic floor muscle (PFM) force 1-year postpartum in a population of primiparous women who delivered vaginally. METHODS: This cross-sectional analysis is an ancillary study to an ongoing prospective cohort study and includes 203 primiparous women. Procedures collected 1-year postpartum included maximal PFM force, grip strength, trunk flexor muscle endurance, percent body fat, intra-abdominal pressure during trunk flexor endurance testing, intra-abdominal pressure during strain, and self-reported physical activity. RESULTS: The mean (SD) age was 29.8 (5.0) years and the mean (SD) body mass index was 24.5 (5.2) kg/m. Nineteen percent were of Hispanic ethnicity. The median (interquartile range) PFM force was 5.05 (2.86-7.94) N. The median (interquartile range) trunk flexor endurance time was 146.0 (78.0-267.0), whereas the mean (SD) grip strength and percent fat were 32.4 (6.4) kg and 29.4% (10.0), respectively.There were no statistically significant associations between PFM force and any of the measures tested on analyses unadjusted or adjusted for self-report of doing PFM exercises. Of other factors evaluated, non-Hispanic ethnicity, increasing age, self-reported family history of pelvic organ prolapse or urinary incontinence, and normal and obese body mass index (both compared with overweight) were associated with lower PFM force. CONCLUSIONS: In primiparous women 1-year postpartum, we found no associations between PFM force and measures of strength and fitness. This study's results are consistent with existing literature that specific, targeted, and consistent pelvic floor exercises are the best way to improve PFM strength.

Variables Affecting Intra-abdominal Pressure During Lifting in the Early Postpartum Period.

OBJECTIVES: Intra-abdominal pressure (IAP) may contribute to pelvic floor health, although the direction and magnitude of such an effect, if any, are not yet known. Identifying individual characteristics, and in particular modifiable factors, associated with higher IAP during recovery from vaginal childbirth might serve to mitigate early pelvic floor dysfunction. The aim of this study was to identify characteristics associated with maximal IAP during lifting in postpartum primiparous women who delivered vaginally. METHODS: At 6 to 10 weeks postpartum, we measured maximal IAP, assessed via an upper vaginal sensor, as participants (enrolled in an ongoing cohort study) lifted a weighted car seat (12.5 kg). We evaluated whether the following independent variables were associated with maximal IAP: age, ethnicity, body mass index, height, abdominal circumference, weight gain during pregnancy, lifting time, breath holding during lifting, lifting technique, measures of muscular fitness, and days since delivery. RESULTS: In the 206 participants, weight, waist circumference, body mass index, and days since delivery were positively associated with mean maximal IAP during lifting, whereas IAP decreased as height increased. As the duration of the lifting task increased, mean maximal IAP during lifting also increased, but there were no associations between lifting technique or breath holding during lifting and IAP. Neither pelvic floor muscle strength nor abdominal muscle endurance was associated with IAP during lifting. CONCLUSIONS: Other than measures of body habitus and lifting duration, we did not identify modifiable factors that could mitigate maximal pressures experienced by the pelvic floor during the early postpartum period.