Predictors of postoperative opioid use in ventral and incisional hernia repair

BACKGROUND

One in two ventral and incisional hernia repair (VIHR) patients have preoperative opioid prescription within a year before procedure. The study's aim was to investigate risk factors of increased postoperative prescription filling in patients with or without preoperative opioid prescription.

METHODS

VIHR cases from 2013 to 2017 were reviewed. State prescription drug monitoring program data were linked to patient records. The primary endpoint was cumulative opioid dose dispensed through post-discharge day 45. Morphine milligram equivalent (MME) was used for uniform comparison.

RESULTS

205 patients were included in the study (average age 53.5 years; 50.7% female). Over 35% met criteria for preoperative opioid use. Preoperative opioid tolerance, superficial wound infection, current smoking status, and any dispensed opioids within 45 days of admission were independent predictors for increased postoperative opioid utilization (p < 0.001).

CONCLUSION

Preoperative opioid use during 45-day pre-admission correlated strongly with postoperative prescription filling in VIHR patients, and several independent risk factors were identified.

Prescription opioid use increases resource utilization following ventral hernia repair

BACKGROUND

Previous studies showed that preoperative opioid use is associated with increased postoperative opioid use and surgical site infection (SSI) in patients undergoing ventral hernia repair (VHR). Orthopedic surgery literature cites increased resource utilization with opioid use. This study aimed to determine the effect of preoperative opioid use on resource utilization after open VHR.

METHODS

A retrospective institutional review board-approved study of VHRs from a single tertiary care practice between 2013 and 2020 was performed. Medical records, the National Surgical Quality Improvement Program database, and Kentucky All Schedule Prescription Electronic Reporting data were reviewed for patient demographics, comorbidities, dispensed opiate prescriptions, hernia characteristics, and outcomes. Univariate logistic regression analyses assessed the effect of each patient's demographic and clinical characteristics. Multivariate logistic regression models analyzed significant factors from the univariate analyses. The primary outcome was resource utilization measured as readmission, emergency department visit, or >2 postoperative clinic visits within 45 days after VHR.

RESULTS

Overall, 381 patients who underwent VHR were identified; of which 101 patients had preoperative dispensed opioids. Multivariate analysis demonstrated that patient gender at birth, any new-onset SSI, and any preoperative opioid use were associated with increased postoperative resource utilization (odds ratio, 1.76; P = .026).

CONCLUSION

Preoperative opioid use was determined as a risk factor that increased resource utilization after open VHR. An understanding of the drivers of the increased use of resources is essential in developing strategies to improve healthcare value. Future research will focus on strategies to reduce the utilization of resources among patients who use opioids.

Prospective, multicenter study of P4HB (Phasix™) mesh for hernia repair in cohort at risk for complications: 3-Year follow-up

BACKGROUND

This study represents a prospective, multicenter, open-label study to assess the safety, performance, and outcomes of poly-4-hydroxybutyrate (P4HB, Phasix™) mesh for primary ventral, primary incisional, or multiply-recurrent hernia in subjects at risk for complications. This study reports 3-year clinical outcomes.

MATERIALS AND METHODS

P4HB mesh was implanted in 121 patients via retrorectus or onlay technique. Physical exam and/or quality of life surveys were completed at 1, 3, 6,12, 18, 24, and 36 months, with 5-year (60-month) follow-up ongoing.

RESULTS

A total of n = 121 patients were implanted with P4HB mesh (n = 75 (62%) female) with a mean age of 54.7 ± 12.0 years and mean BMI of 32.2 ± 4.5 kg/m2 (±standard deviation). Comorbidities included: obesity (78.5%), active smokers (23.1%), COPD (28.1%), diabetes mellitus (33.1%), immunosuppression (8.3%), coronary artery disease (21.5%), chronic corticosteroid use (5.0%), hypo-albuminemia (2.5%), advanced age (5.0%), and renal insufficiency (0.8%). Hernias were repaired via retrorectus (n = 45, 37.2% with myofascial release (MR) or n = 43, 35.5% without MR), onlay (n = 8, 6.6% with MR or n = 24, 19.8% without MR), or not reported (n = 1, 0.8%). 82 patients (67.8%) completed 36-month follow-up. 17 patients (17.9% ± 0.4%) experienced hernia recurrence at 3 years, with n = 9 in the retrorectus group and n = 8 in the onlay group. SSI (n = 11) occurred in 9.3% ± 0.03% of patients.

CONCLUSIONS

Long-term outcomes following ventral hernia repair with P4HB mesh demonstrate low recurrence rates at 3-year (36-month) postoperative time frame with no patients developing late mesh complications or requiring mesh removal. 5-year (60-month) follow-up is ongoing.

Parastomal Hernia Repair Outcomes: A Nine-Year Experience

Parastomal hernias (PHs) frequently complicate enterostomy creation. Decision for PH repair (PHR) is driven by patient symptoms due to the frequency of complications and recurrences. The European Hernia Society (EHS) PH classification is based on the PH defect size and the presence/ absence of concomitant incisional hernia. The aim of this study was to evaluate PHR outcomes based on EHS classification. An Institutional Review Board–approved retrospective review of a prospective database between 2009 and 2017 was performed. Patient demographics, enterostomy type, EHS classification, operative technique, and clinical outcomes (postoperative complications, 30-day readmission, and PH recurrence) were obtained. Cases were analyzed by EHS classifications I and II (SmallPH) versus III and IV (LargePH). Sixty-two patients underwent PHR (35: SmallPH, 27: LargePH). Patient groups (SmallPH vs LargePH) were similar based on American Society of Anesthesiologists Class III and obesity. Hernia recurrence was seen in 26 per cent of repairs with no difference between groups. The median recurrence-free survival was 3.9 years. There was no difference in superficial SSI, deep SSI, nonwound complications, or readmission between SmallPH and LargePH. Both small and large PHs experience similar outcomes after repair. Strategies to improve outcomes should be developed and implemented universally across all EHS PH classes.

Hernia Repair Strength Enhanced With Antioxidants

BACKGROUND

Incisional hernia is one of the most common complications of abdominal surgery, and repairs are associated with significant recurrence rates. Mesh repairs are associated with the best outcomes, but failures are not uncommon. Doxycycline has been demonstrated to enhance mesh hernia repair outcomes with associated increases in collagen deposition and improved tensiometric strength. This study compares the outcomes of incisional hernia repair with doxycycline administration and the antioxidant tempol.

MATERIALS AND METHODS

Twenty-eight male Sprague Dawley rats underwent a midline hernia creation and an intraabdominal polypropylene mesh repair. The animals were administered saline, doxycycline, tempol, or both, daily for 8 wk. The abdominal wall was harvested at 8 wk and tensiometric strength and biochemical analysis was performed.

RESULTS

The tensiometric strength of the repair was increased in all experimental groups. Collagen type 1 deposition was increased, and collagen type 3 deposition was decreased in each of the experimental groups relative to control. There was no difference in MMP-2 and MMP-9 levels between control and experimental groups.

CONCLUSIONS

The hernia repair strength is equally enhanced with the administration of doxycycline or tempol. Dual therapy provided no benefit over treatment with either single agent. All treatment groups had an increase in collagen type 1:3 ratios, but the mechanism is not well understood. The benefits of antioxidant treatment following hernia repair are similar to treatment with doxycycline. Given the high frequency of incisional hernia repair failures, this study has implications for improving outcomes following ventral hernia repair through the use of either doxycycline or antioxidant therapy.

Totally extraperitoneal approach for open complex abdominal wall reconstruction

BACKGROUND

Ventral hernia repair is typically performed via a transabdominal approach and the peritoneal cavity is opened and explored. Totally extraperitoneal ventral hernia repair (TEVHR) facilitates dissection of the hernia sac without entering the peritoneal cavity. This study evaluates our experience of TEVHR, addressing technique, decision-making, and outcomes.

METHODS

This is an IRB-approved retrospective review of open TEVHR performed between January 2012 and December 2016. Medical records were reviewed for patient demographics, operative details, postoperative outcomes, hospital readmissions, and reoperations.

RESULTS

One hundred sixty-six patients underwent TEVHR (84 males, 82 females) with a mean BMI range of 30-39. Eighty-six percent of patients underwent repair for primary or first-time recurrent hernia, and 89% CDC wound class I. Median hernia defect size was 135 cm². Hernia repair techniques included Rives-Stoppa (34%) or transversus abdominis release (57%). Median operative time was 175 min, median blood loss 100 mL, and median length of stay 4 days. There were no unplanned bowel resections or enterotomies. Four cases required intraperitoneal entry to explant prior mesh. Wound complication rate was 27%: 9% seroma drainage, 18% superficial surgical site infection (SSI), and 2% deep space SSI. Five patients (3%) required reoperation for wound or mesh complications. Over the study, four patients were hospitalized for postoperative small bowel obstruction and managed non-operatively. Of the 166 patients, 96%, 54%, and 44% were seen at 3-month, 6-month, and 12-month follow-ups, respectively. Recurrences were observed in 2% of patients at 12-month follow-up. One patient developed an enterocutaneous fistula 28 months postoperatively.

CONCLUSIONS

TEVHR is a safe alternative to traditional transabdominal approaches to ventral hernia repair. The extraperitoneal dissection facilitates hernia repair, avoiding peritoneal entry and adhesiolysis, resulting in decreased operative times. In our study, there was low risk for postoperative bowel obstruction and enterotomy. Future prospective studies with long-term follow-up are required to draw definitive conclusions.

Laparoscopic parastomal hernia repair delays recurrence relative to open repair

BACKGROUND

Mesh repair of parastomal hernia is widely accepted as superior to non-mesh repair, yet the most favorable surgical approach is a subject of continued debate. The aim of this study was to compare the clinical outcomes of open versus laparoscopic parastomal hernia repair.

METHODS

An IRB-approved retrospective review was conducted comparing laparoscopic (LPHR) or open (OPHR) parastomal hernia repair performed between 2009 and 2017 at our facilities. Patient demographics, preoperative characteristics, operative details, and clinical outcomes were compared by surgical approach. Subgroup analysis was performed by location of mesh placement. Repair longevity was measured using Kaplan-Meier method and Cox proportional hazards regression. Intention to treat analysis was used for this study based on initial approach to the repair.

RESULTS

Sixty-two patients (average age of 61 years) underwent repair (31 LPHR, 31 OPHR). Patient age, gender, BMI, ASA Class, and comorbidity status were similar between OPHR and LPHR. Stoma relocation was more common in OPHR (32% vs 7%, p = .022). Open sublay subgroup was similar to LPHR in terms of wound class and relocation. Open "Other" and Sublay subgroups resulted in more wound complications compared to LPHR (70% and 48% vs 27%, p = .036). Operative duration and hospital length of stay were less with LPHR (p < .001). After adjustment for prior hernia repair, risk of recurrence was higher for OPHR (p = .022) and Open Sublay and Other subgroups compared to LPHR (p = .005 and p = .027, respectively).

CONCLUSIONS

Laparoscopic repair of parastomal hernias is associated with shorter operative duration, decreased length of stay, fewer short-term wound complications, and increased longevity of repair compared to open repairs. Direct comparison of repair longevity between LPHR and OPHR with mesh using Kaplan-Meier estimate is unique to this study. Further study is warranted to better understand methods of parastomal hernia repair associated with fewer complications and increased durability.

Costs and Complications Associated with Infected Mesh for Ventral Hernia Repair

Background: Mesh hernia repair is widely accepted because of the associated reduction in hernia recurrence compared with suture-based repair. Despite initiatives to reduce risk, mesh infection and mesh removal are a significant challenge. In an era of healthcare value, it is essential to understand the global cost of care, including the incidence and cost of complications. The purpose of this study was to identify the outcomes and costs of care of patients who required the removal of infected hernia mesh. Methods: A review of databases from 2006 through June 2018 identified patients who underwent both ventral hernia repair (VHR) and re-operation for infected mesh removal. Patient demographic and operative details for both procedures, including age, Body Mass Index, mesh type, amount of time between procedures, and information regarding interval procedures were obtained. Clinical outcome measures were the length of the hospital stay, hospital re-admission, incision/non-incision complications, and re-operation. Hospital cost data were obtained from the cost accounting system and were combined with the clinical data for a cost and clinical representation of the cases. Results: Thirty-four patients underwent both VHR and removal of infected mesh material over the 12-year time frame and were included in the analyses; the average age at VHR was 48 years, and 16 patients (47%) were female. Following VHR, 21 patients (62%) experienced incision complications within 90 days post-operatively, the complications ranging from superficial surgical site infection (SSI) to evisceration. A mean of 22.65 months passed between procedures. After mesh removal, 16 patients (47%) experienced further incisional complications; and 22 (65%) patients had at least one re-admission. Eighteen patients (53%) required a minimum of one additional related operative procedure after mesh removal. Median hospital costs nearly doubled (p < 0.001) for the mesh removal ($23,841 [interquartile range {IQR} $13,596-$42,148]) compared with the VHR admission ($13,394 [IQR $8,424-$22,161]) not accounting for re-admission costs. A majority experienced hernia recurrence subsequent to mesh removal. Conclusions: Mesh infection after hernia repair is associated with significant morbidity and costs. Hospital re-admission, re-operations, and recurrences are common among these patients, resulting in greater healthcare resource utilization. Development of strategies to prevent mesh infection, identify patients most likely to experience infectious complications, and define best practices for the care of patients with mesh infection are needed.

Clinical and Quality of Life Assessment of Patients Undergoing Laparoscopic Hiatal Hernia Repair

Hiatal hernia repair (HHR) and fundoplication are similarly performed among all hiatal hernia types with similar techniques. This study evaluates the effect of HHR using a standardized technique for cruroplasty with a reinforcing polyglycolic acid and trimethylene carbonate mesh (PGA/TMC) on patient symptoms and outcomes. A retrospective review of patient perioperative characteristics and postoperative outcomes was conducted for cases of laparoscopic hiatal hernia repair (LHHR) using a PGA/TMC mesh performed over 21 months. Gastroesophageal reflux disease symptom questionnaire responses were compared between preoperative and three postoperative time points. Ninety-six patients underwent LHHR with a PGA/TMC mesh. Post-operatively, the number of overall symptoms reported by patients decreased across all postoperative periods ( P < 0.001). Patients reported a significant reduction in antacid use long term ( P < 0.001). Laryngeal and regurgitation symptoms decreased at all time points ( P < 0.05). There was no difference in dysphagia preoperatively and postoperatively at any time point. Individuals undergoing HHR with PGA/TMC mesh experienced improved regurgitation and laryngeal symptoms, and decreased use of antacid medication.

Clinical and Quality of Life Assessment of Patients Undergoing Laparoscopic Hiatal Hernia Repair

Hiatal hernia repair (HHR) and fundoplication are similarly performed among all hiatal hernia types with similar techniques. This study evaluates the effect of HHR using a standardized technique for cruroplasty with a reinforcing polyglycolic acid and trimethylene carbonate mesh (PGA/TMC) on patient symptoms and outcomes. A retrospective review of patient perioperative characteristics and postoperative outcomes was conducted for cases of laparoscopic hiatal hernia repair (LHHR) using a PGA/TMC mesh performed over 21 months. Gastroesophageal reflux disease symptom questionnaire responses were compared between preoperative and three postoperative time points. Ninety-six patients underwent LHHR with a PGA/TMC mesh. Postoperatively, the number of overall symptoms reported by patients decreased across all postoperative periods (P < 0.001). Patients reported a significant reduction in antacid use long term (P < 0.001). Laryngeal and regurgitation symptoms decreased at all time points (P < 0.05). There was no difference in dysphagia preoperatively and postoperatively at any time point. Individuals undergoing HHR with PGA/TMC mesh experienced improved regurgitation and laryngeal symptoms, and decreased use of antacid medication.

Validation and Extension of the Ventral Hernia Repair Cost Prediction Model

BACKGROUND

Repair of ventral and incisional hernias remains a costly challenge for health care systems. In a previous study of a single surgeon's elective open ventral hernia repair (VHR) practice, a cost model was developed, which predicted over 70% of hospital cost variation. The purpose of the present study was to evaluate the ventral hernia cost model with multiple surgeons' elective open VHR cases and extending to include nonelective and laparoscopic VHR.

MATERIALS AND METHODS

With the University of Kentucky Institutional Review Board approval, elective and emergent cases of open and laparoscopic VHR performed by multiple surgeons over 3 y were identified. Perioperative variables were obtained from the local American College of Surgeons National Surgery Quality Improvement Program database and electronic medical record review. Hospital cost data were obtained from the hospital cost accounting system. Forward multivariable regression of log-transformed costs identified independent cost drivers (P for entry < 0.05, and P for exit > 0.10).

RESULTS

Of the 387 VHRs, 74% were open repairs; mean age was 55 y, and 52% of patients were female. For open, elective cases (n = 211; mean cost of $19,145), the previously reported six-factor cost model predicted 45% of the total cost variation. With all VHRs included, additional variables were found to independently drive costs, predicting 59% of the total cost variation from the base cost. The biggest cost drivers were inpatient status (+$1013), use of biologic mesh (+$1131), preoperative systemic inflammatory response syndrome/sepsis (+$894), and preoperative open wound (+$786).

CONCLUSIONS

Ventral hernia repair cost variability is predictable. Understanding the independent drivers of cost may be helpful in controlling costs and in negotiating appropriate reimbursement with payers.

Parastomal Hernia Repair Outcomes: A Nine-Year Experience

Parastomal hernias (PHs) frequently complicate enterostomy creation. Decision for PH repair (PHR) is driven by patient symptoms due to the frequency of complications and recurrences. The European Hernia Society (EHS) PH classification is based on the PH defect size and the presence/absence of concomitant incisional hernia. The aim of this study was to evaluate PHR outcomes based on EHS classification. An Institutional Review Board-approved retrospective review of a prospective database between 2009 and 2017 was performed. Patient demographics, enterostomy type, EHS classification, operative technique, and clinical outcomes (postoperative complications, 30-day readmission, and PH recurrence) were obtained. Cases were analyzed by EHS classifications I and II (SmallPH) versus III and IV (LargePH). Sixty-two patients underwent PHR (35: SmallPH, 27: LargePH). Patient groups (SmallPH vs LargePH) were similar based on American Society of Anesthesiologists Class III and obesity. Hernia recurrence was seen in 26 per cent of repairs with no difference between groups. The median recurrence-free survival was 3.9 years. There was no difference in superficial SSI, deep SSI, nonwound complications, or readmission between SmallPH and LargePH. Both small and large PHs experience similar outcomes after repair. Strategies to improve outcomes should be developed and implemented universally across all EHS PH classes.

Perioperative factors associated with pain following open ventral hernia repair

BACKGROUND

Effective pain control following open ventral and incisional hernia repair (VHR) impacts all aspects of patient recovery. To reduce opioid use and enhance pain management, multimodal therapy is thought to be beneficial. The purpose of this study was to identify patient characteristics associated with perioperative patient-reported pain scores.

METHODS

With IRB approval, surgical databases were searched for cases of open VHR performed over 3 years. Based on a retrospective chart review, modes of pain management and visual analog scale (VAS) pain scores were recorded in 12-h intervals to hospital discharge or to 8 days post-operation. Forward stepwise multivariable regression assessed the independent contribution of the perioperative factors to VAS pain scores.

RESULTS

Included in the analyses were 175 patients that underwent VHR. Average age was 55 years (+/- 12.8), and half were female (50.9%). Factors independently associated with increased preoperative VAS pain scores included preoperative opioid use, preoperative open wound, CDC Wound Class II, and prior hernia repair(s). Patients with epidural for postoperative pain had significantly decreased VAS pain scores across the time continuum. Operative factors significantly associated with increased preoperative VAS pain score included median hernia defect size, concomitantly performed procedure(s), duration of operation, and estimated blood loss. Greater preoperative VAS pain score predicted increased pain at each postoperative time point (all p < .05).

CONCLUSIONS

Preoperative pain and opioid use are associated with increased pain postoperatively. Epidural analgesia effectively results in decreased patient-reported pain. Increased operative complexity is associated with increased preoperative pain scores.

Associations between anxiolytic medications and ventral hernia repair

PURPOSE

This study examines the relationship between anxiolytic medications (AXM) on outcomes following ventral hernia repair.

METHODS

A single-center review of prospectively obtained perioperative and 30-day outcome data, including AXM use at admission, as part of the National Surgery Quality Improvement Program.

RESULTS

Sixty-three of the 393 patients who presented for ventral hernia repair were taking an AXM (15.6%). AXM users were more likely to have a higher ASA class, dyspnea, and treated hypertension (p < 0.05). AXM use was associated with increased operative duration, hernia size, increased estimated blood loss, and need for component separation. After adjusting for medical comorbidities, AXM users were not found to have greater 30-day morbidity or mortality. Patients taking AXM were found to have greater length of stay and increased hospital readmissions.

CONCLUSIONS

Patients taking anxiolytic medications undergoing ventral hernia repairs have higher ASA scores, more complex hernia characteristics, and require more concurrent procedures. They were found to have longer operative times, increased blood loss, greater duration of hospital stay, and increased readmissions that were associated with the increased perioperative risk factors. Further studies are required to determine causal links.

Early outcomes of an enhanced recovery protocol for open repair of ventral hernia

BACKGROUND

Enhanced recovery after surgery (ERAS) protocols are evidence-based quality improvement pathways reported to be associated with improved patient outcomes. The purpose of this study was to compare short-term outcomes for open ventral hernia repair (VHR) before and after implementation of an ERAS protocol.

METHODS

After obtaining IRB approval, surgical databases were searched for VHR cases for two years prior and eleven months after protocol implementation for retrospective review. Groups were compared on perioperative characteristics and clinical outcomes using chi-square, Fisher's exact, or Mann-Whitney U test, as appropriate.

RESULTS

One hundred and seventy-one patients underwent VHR (46 patients with ERAS protocol in place and 125 historic controls). Age, gender, ASA Class, comorbidities, and smoking status were similar between the two groups. Body mass index was lower among ERAS patients (p = .038). ERAS patients had earlier return of bowel function (median 3 vs. 4 days) (p = .003) and decreased incidence of superficial surgical site infection (SSI) (7 vs. 25%) (p = .008) than controls.

CONCLUSION

An ERAS protocol for VHR demonstrated improved patient outcomes. A system-wide culture focused on enhanced recovery is needed to ensure improved patient outcomes.

Concomitant open ventral hernia repair: what is the financial impact of performing open ventral hernia with other abdominal procedures concomitantly?

BACKGROUND

Open ventral hernia repair (VHR) is often performed in conjunction with other abdominal procedures. Clinical outcomes and financial implications of VHR are becoming better understood; however, financial implications of concomitant VHR during other abdominal procedures are unknown. This study aimed to evaluate the financial implications of adding VHR to open abdominal procedures.

METHODS

This IRB-approved study retrospectively reviewed hospital costs to 180-day post-discharge of standalone VHRs, isolated open abdominal surgeries (bowel resection or stoma closure, removal of infected mesh, hysterectomy or oophorectomy, panniculectomy or abdominoplasty, open appendectomy or cholecystectomy), performed at our institution from October 1, 2011 to September 30, 2014. The perioperative risk data were obtained from the local National Surgery Quality Improvement Program (NSQIP) database, and resource utilization data were obtained from the hospital cost accounting system.

RESULTS

345 VHRs, 1389 open abdominal procedures as described, and 104 concomitant open abdominal and VHR cases were analyzed. The VHR-only group had lower ASA Class, shorter operative duration, and a higher percentage of hernias repaired via separation of components than the concomitant group (p < 0.001). The median hospital cost for VHR-alone was $12,900 (IQR: $9500-$20,700). There were significant increases to in-hospital costs when VHR was combined with removing an infected mesh (63%) or with bowel resections or stoma closures (0.7%). The addition of VHR did not cause a significant change in 180-day post-discharge costs for any of the procedures.

CONCLUSIONS

This study noted decreased costs when combining VHR with panniculectomy or abdominoplasty and hysterectomy or oophorectomy. For removal of infected mesh and bowel resection or stoma closure, waiting, when feasible, is recommended. Given the impending changes in financial reimbursements in healthcare in the United States, it is prudent that future studies evaluate further the clinical and fiscal benefit of concomitant procedures.

Complex Ventral Hernia Repair with Acellular Dermal Matrices: Clinical and Quality of Life Outcomes

Acellular dermal matrices (ADMs) are used in conjunction with complex hernia repair, but their efficacy is often debated. This study assesses clinical and quality of life (QOL) outcomes in multiply comorbid patients undergoing complex ventral hernia repair using ADMs. After obtaining institutional review board approval, a prospective study was conducted evaluating patients undergoing complex ventral incisional hernia repair with abdominal wall reconstruction (AWR) using either human (Flex HD) or porcine ADM (Strattice). Patient accrual occurred over three years. Demographics, comorbid conditions, and operative details were recorded. Postoperative two-week, six-week, six-month, and one-year follow-up occurred. Primary outcomes measures include wound occurrence, QOL parameters using the Short Form-12 health survey, and hernia recurrence. Groups were compared using chi-squared, Fisher's exact, Mann-Whitney U, or t tests as appropriate. Significance was set at P < 0.05. Thirty-five patients underwent hernia repair using ADM: mean age = 58 years, mean body mass index = 34 kg/m2, >50 per cent Centers for Disease Control and Prevention Wound Class II and above, >50 per cent recurrent hernia repair, and 25 per cent current or previous mesh infection. Twenty patients (57%) experienced surgical site occurrences, 15 (43%) wound infections, and 5 (14%) recurrences with a median follow-up of one year. All Short Form-12 QOL indicators improved at 12 months compared with baseline (NS). Outcomes were similar between mesh types. In conclusion, abdominal wall reconstruction for complex hernias using biologic materials is safe but has significant morbidity. Wound complications occur in over half of all patients and are not impacted by ADM type. There is no decrement in QOL one year after hernia repair despite associated morbidity.

Complex Ventral Hernia Repair with Acellular Dermal Matrices: Clinical and Quality of Life Outcomes

Acellular dermal matrices (ADMs) are used in conjunction with complex hernia repair, but their efficacy is often debated. This study assesses clinical and quality of life (QOL) outcomes in multiply comorbid patients undergoing complex ventral hernia repair using ADMs. After obtaining institutional review board approval, a prospective study was conducted evaluating patients undergoing complex ventral incisional hernia repair with abdominal wall reconstruction (AWR) using either human (Flex HD) or porcine ADM (Strattice). Patient accrual occurred over three years. Demographics, comorbid conditions, and operative details were recorded. Postoperative two-week, six-week, six-month, and one-year follow-up occurred. Primary outcomes measures include wound occurrence, QOL parameters using the Short Form-12 health survey, and hernia recurrence. Groups were compared using chi-squared, Fisher's exact, Mann-Whitney U, or t tests as appropriate. Significance was set at P < 0.05. Thirty-five patients underwent hernia repair using ADM: mean age = 58 years, mean body mass index = 34 kg/m2, >50 per cent Centers for Disease Control and Prevention Wound Class II and above, >50 per cent recurrent hernia repair, and 25 per cent current or previous mesh infection. Twenty patients (57%) experienced surgical site occurrences, 15 (43%) wound infections, and 5 (14%) recurrences with a median follow-up of one year. All Short Form-12 QOL indicators improved at 12 months compared with baseline (NS). Outcomes were similar between mesh types. In conclusion, abdominal wall reconstruction for complex hernias using biologic materials is safe but has significant morbidity. Wound complications occur in over half of all patients and are not impacted by ADM type. There is no decrement in QOL one year after hernia repair despite associated morbidity.

Do risk calculators accurately predict surgical site occurrences?

INTRODUCTION

Current risk assessment models for surgical site occurrence (SSO) and surgical site infection (SSI) after open ventral hernia repair (VHR) have limited external validation. Our aim was to determine (1) whether existing models stratify patients into groups by risk and (2) which model best predicts the rate of SSO and SSI.

METHODS

Patients who underwent open VHR and were followed for at least 1 mo were included. Using two data sets-a retrospective multicenter database (Ventral Hernia Outcomes Collaborative) and a single-center prospective database (Prospective)-each patient was assigned a predicted risk with each of the following models: Ventral Hernia Risk Score (VHRS), Ventral Hernia Working Group (VHWG), Centers for Disease Control and Prevention Wound Class, and Hernia Wound Risk Assessment Tool (HW-RAT). Patients in the Prospective database were also assigned a predicted risk from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). Areas under the receiver operating characteristic curve (area under the curve [AUC]) were compared to assess the predictive accuracy of the models for SSO and SSI. Pearson's chi-square was used to determine which models were able to risk-stratify patients into groups with significantly differing rates of actual SSO and SSI.

RESULTS

The Ventral Hernia Outcomes Collaborative database (n = 795) had an overall SSO and SSI rate of 23% and 17%, respectively. The AUCs were low for SSO (0.56, 0.54, 0.52, and 0.60) and SSI (0.55, 0.53, 0.50, and 0.58). The VHRS (P = 0.01) and HW-RAT (P < 0.01) significantly stratified patients into tiers for SSO, whereas the VHWG (P < 0.05) and HW-RAT (P < 0.05) stratified for SSI. In the Prospective database (n = 88), 14% and 8% developed an SSO and SSI, respectively. The AUCs were low for SSO (0.63, 0.54, 0.50, 0.57, and 0.69) and modest for SSI (0.81, 0.64, 0.55, 0.62, and 0.73). The ACS-NSQIP (P < 0.01) stratified for SSO, whereas the VHRS (P < 0.01) and ACS-NSQIP (P < 0.05) stratified for SSI. In both databases, VHRS, VHWG, and Centers for Disease Control and Prevention overestimated risk of SSO and SSI, whereas HW-RAT and ACS-NSQIP underestimated risk for all groups.

CONCLUSIONS

All five existing predictive models have limited ability to risk-stratify patients and accurately assess risk of SSO. However, both the VHRS and ACS-NSQIP demonstrate modest success in identifying patients at risk for SSI. Continued model refinement is needed to improve the two highest performing models (VHRS and ACS-NSQIP) along with investigation to determine whether modifications to perioperative management based on risk stratification can improve outcomes.

Implementation of a low-cost laparoscopic skills curriculum in a third-world setting

BACKGROUND

Training outside the operating room has become a mainstay of surgical education. Laparoscopic training often takes place in a simulation setting. Advanced laparoscopic procedures are now commonplace, even in third-world countries with minimal hospital resources. We sought to implement a low-cost laparoscopic skills curriculum in a general surgery residency program in East Africa.

STUDY DESIGN

The laparoscopic skills curriculum created and validated at the University of Kentucky was presented to the 10 general surgery residents at Tenwek Hospital. The curriculum and all materials were purchased for approximately $50 (USD). The residents in Kenya had access to laparoscopic trainer boxes and personal laptops to perform the simulations. Residents were timed on their performance at the initiation of the project and after 3 weeks of practice.

RESULTS

Residents were tested on 3 separate tasks (cannulation drill, peg board, and rope pass). At the initiation of the project, residents were unable to complete the 3 tasks chosen for timing without a critical error (i.e., dropping a peg out of view). After 3 weeks of independent practice, residents were able to successfully complete the tasks, nearing the time limits established in the curriculum manual. Additional practice and testing sessions are scheduled for the remainder of the year.

CONCLUSIONS

Implementation of a low-cost laparoscopic skills curriculum in a third-world setting is feasible. This approach offers much-needed exposure and opportunities for residents with extremely limited resources and promises to be a vital aspect of the growing surgical residency training in third-world settings.

Complex ventral hernia repair with a human acellular dermal matrix

Purpose

The ideal approach to complex ventral hernia repair is frequently debated. Differences in processing techniques among biologic materials may impact hernia repair outcomes. This study evaluates the outcomes of hernia repair with a terminally sterilized human acellular dermal matrix (TS-HADM) (AlloMax^® Surgical Graft, by C. R. Bard/Davol, Inc., Warwick, RI, USA) treated with low-dose gamma irradiation.

Methods

A single-arm multi-center retrospective observational study of patients undergoing hernia repair with TS-HADM was performed. Data analyses were exploratory only; no formal hypothesis testing was pre-specified.

Results

Seventy-eight patients (43F, 35M) underwent incisional hernia repair with a TS-HADM. Mean follow-up was 20.5 months. Preoperative characteristics include age of 56.6 ± 11.1 years, BMI 36.7 ± 9.9 kg/m², and mean hernia defect size 187 cm². Sixty-five patients underwent component separation technique (CST) with a reinforcing graft. Overall, 21.8 % developed recurrences. Recurrences occurred in 15 % of patients repaired with CST. Major wound complications occurred in 31 % of patients overall. Based upon CDC surgical wound classification, major wound complications were seen in 26, 40, 56, and 50 % of Class 1, 2, 3, and 4 wounds, respectively. No grafts required removal.

Conclusions

Hernia recurrences are not uncommon following complex abdominal wall reconstruction. Improved outcomes are seen when a TS-HADM is utilized as reinforcement to primary fascial closure.

The endoscopic component separation technique for hernia repair results in reduced morbidity compared to the open component separation technique

PURPOSE

The component separation technique for hernia repair results in significant wound morbidity due to the need for large undermining skin flaps. The endoscopic component separation technique allows for advancement of the abdominal wall while preserving the blood supply originating from the epigastric vessels. This study compares the outcomes following hernia repair utilizing these techniques.

METHODS

A retrospective review of patients undergoing component separation or endoscopic component separation hernia repair from 2008 to 2010. Patients underwent open component separation or endoscopic component separation with closure of the linea alba and reinforcement with mesh.

RESULTS

Thirty-five patients that underwent a component separation [14 open component separation (CST) and 21 that underwent endoscopic component separation (ECST)] were identified. There was no difference in hospital length of stay (CST 5.0 ± 3.0 days vs ECST 6.3 ± 3.6 days, P = 0.28) or operating room times (CST; 268 ± 62 min vs ECST; 229 ± 57 min, P = 0.07). Wound complications occurred in 57% of CST and 19% of ECST, P = 0.03. One recurrent hernia was identified in the ECST group with a mean follow up of 8 months (range 1-21 months). No recurrences were seen in the CST group.

CONCLUSIONS

ECST is associated with comparable hospital length of stay and operative times and reduced wound complications compared to CST.

Hydrated vs. freeze-dried human acellular dermal matrix for hernia repair: a comparison in a rabbit model

BACKGROUND

Abdominal wall hernias commonly occur following laparotomy. Biologic grafts are used to treat these hernias due to their biocompatibility and their ability to serve as a matrix for tissue regeneration and remodeling. Freeze-dried human acellular dermal matrices (F-HADMs) have been shown to be effective in abdominal wall defect repair. Hydrated human acellular dermal matrices (H-HADMs) have not been previously evaluated. This study evaluates H-HADM and F-HADM in the repair of abdominal wall hernias in the rabbit.

METHODS

Thirty-six 3-4-kg New Zealand white rabbits underwent laparotomy with the creation of a hernia. After defect reperitonealization, the animals underwent hernia repair with H-HADM, F-HADM, or primary repair. Within each group, four animals were survived for 4, 8, and 20 weeks. The outcomes evaluated included recurrences, adhesions, histology, immunohistochemistry, and tensiometry.

RESULTS

Thirty-five animals underwent abdominal wall hernia repair. One animal in the F-HADM group developed a recurrent hernia. No significant difference was demonstrated in adhesion scores between the H-HADM (0.75) and F-HADM (0.83) groups. Tensiometry demonstrated no differences in the forces required to disrupt the graft from the native fascia between H-HADM and F-HADM at any time point. H-HADM demonstrated fewer white blood cells (WBC) and eosinophils (EOS) per high-powered field (hpf) than F-HADM at 4 weeks (144 WBC/hpf vs. 534 WBC/hpf, P < 0.05; 87 EOS/hpf vs. 304 EOS/hpf, P < 0.05) and 8 weeks (104 WBC/hpf vs. 314 WBC/hpf, P < 0.05; 41 EOS/hpf vs. 149 EOS/hpf, P < 0.05). At 20 weeks, there was no difference in WBC or EOS (134 WBC/hpf vs. 144 WBC/hpf, P = NS; 86 EOS/hpf vs. 104 EOS/hpf, P = NS). Immunohistochemistry for CD31 demonstrated no difference in vascularity at any time point.

CONCLUSIONS

H-HADM and F-HADM demonstrate comparable results in abdominal wall hernia treatment in a rabbit model. With both grafts, the weakest area of the repair occurs at the graft and native fascia interface. Hernia repairs with H-HADM and F-HADM demonstrate similar incidences of adhesions and tensile strength characteristics. H-HADM demonstrates a reduced inflammatory response at 4 and 8 weeks compared to F-HADM. Both H-HADM and F-HADM demonstrate similar amounts of vascular ingrowth.

Complications of laparoscopic incisional-ventral hernia repair: the experience of a single institution

BACKGROUND

Laparoscopic incisional-ventral hernia repair (LIVH) is used with increasing frequency for the morbidly obese and for complex and recurrent hernias. The experience of a single institution with this technique is reviewed and the findings and complications are presented.

METHODS

Data were collected retrospectively for a single surgeon's series of patients undergoing LIVH at the institution described in this report.

RESULTS

The review showed a complication rate of 15.2%, a recurrence rate of 2%, and a prosthetic infection rate of 2%. Patients with a body mass index greater than 30 cm/m2 accounted for 73% of the complications and made up 62.2% of the patients.

CONCLUSIONS

The LIVH procedure may be safely performed with low complication and recurrence rates even for the obese, allowing ventral hernia repair to be performed safely with good results. The LIVH technique should be considered for the repair of all incisional and ventral hernias requiring repair with a mesh prosthesis.

Gluteal compartment syndrome and sciatica after bone marrow biopsy: a case report and review of the literature

The gluteal region is not commonly thought of as a compartment, yet nondistensible osseofascial boundaries do exist. As with any case of compartment syndrome expedient therapeutic measures are critical to salvaging neuromuscular function. The gluteal compartment is unique, however, because of its tremendous muscle mass and great potential for producing devastating systemic sequelae. Gluteal compartment syndrome is most commonly associated with unconscious patients who are recumbent for prolonged periods, but trauma, spontaneous bleeding, and overexertion can also cause it. We present a case report of gluteal compartment syndrome after bone marrow biopsy of the iliac crest. Recognizing gluteal compartment syndrome as an entity and maintaining a high index of suspicion for its development especially in unconscious patients can avert disaster regardless of etiology.

Gluteal Compartment Syndrome and Sciatica after Bone Marrow Biopsy: A Case Report and Review of the Literature

The gluteal region is not commonly thought of as a compartment, yet nondistensible osseofascial boundaries do exist. As with any case of compartment syndrome expedient therapeutic measures are critical to salvaging neuromuscular function. The gluteal compartment is unique, however, because of its tremendous muscle mass and great potential for producing devastating systemic sequelae. Gluteal compartment syndrome is most commonly associated with unconscious patients who are recumbent for prolonged periods, but trauma, spontaneous bleeding, and overexertion can also cause it. We present a case report of gluteal compartment syndrome after bone marrow biopsy of the iliac crest. Recognizing gluteal compartment syndrome as an entity and maintaining a high index of suspicion for its development especially in unconscious patients can avert disaster regardless of etiology.

Chemistry and anti-HIV properties of 2'-fluoro-2',3'-dideoxyarabinofuranosylpyrimidines

The synthesis, chemistry, biochemistry, and anti-HIV activity of a series of 1-(2,3-dideoxy-2-fluoro-beta-D-threopentofuranosyl)pyrimidines have been studied in an attempt to find useful anti-AIDS drugs. Synthesis is carried out via a 2,3-dideoxyribose intermediate which facilitates the preparation of analogues by removing the sugar 3'-hydroxyl group prior to, rather than after, condensation with a uracil or cytosine aglycon. The 2'-F-dd-uridine analogues 7a-d (with H, F, Cl, and CH3 substitution in the 5-position) as well as the 4-deoxy compound (12b) are nonprotective to ATH8 or CEM cells infected with HIV-1. In the corresponding cytidine series, the 5-chloro analogue (11) is inactive. However, 2'-fluoro-2',3'-dideoxyarabinosylcytosine, 10a, and its 5-fluoro analogue, 10b, are both active. While neither compounds is a potent as ddC or 5-F-ddC (2b), 10b gives complete protection against the cytopathic effects of HIV in both host cell lines. 2'-Fluoro substitution confers increased chemical and enzymatic stability on dideoxynucleosides. Even though dideoxy pyrimidine nucleosides are inherently more stable than the corresponding purine analogues toward acid-catalyzed cleavage of the glycosidic bond, 2'-fluoro substitution (10a) still increases stabilization relative to ddC (2b). No detectable deamination by partially purified cytidine deaminase is observed with the 2'-fluoro compounds 10a, 10b, or 11 under conditions which rapidly deaminate cytidine. A small amount of 2'-F-dd-ara-U (7a) is formed from 10a in monkey plasma after greater than 24 h of exposure. The octanol-water partition coefficients for the dideoxynucleosides in this study indicate their hydrophilic character, with log P values varying from -0.28 to -1.18.

Laparoscopic pancreatic cystgastrostomy: the lesser sac technique

Management of pancreatic pseudocysts has remained largely unchanged during the past century. Excision and drainage procedures remain the mainstay of therapy for large, persistent, or symptomatic pseudocysts. Laparoscopic approaches to the management of pancreatic pseudocysts have been previously described. The lesser sac approach is an effective means of creating a hemostatic cystgastrostomy through a single posterior gastrotomy. This procedure is performed by creating a cystotomy and posterior wall gastrotomy through which an endoscopic stapler is applied. The cystotomy-gastrotomy is closed using laparoscopically placed sutures. An endoscope is inserted into the stomach and pseudocyst at the conclusion of the procedure to ensure an airtight anastomosis. The lesser sac approach to pancreatic cystgastrostomy allows for a minimally invasive approach to the management of pancreatic pseudocysts using a single gastrotomy.

Evaluation of a fluorogenic derivatization method for the reversed-phase HPLC analysis of 2'-beta-fluoro-2',3'-dideoxyadenosine, a new anti-AIDS drug

High sensitivity (10(-7) to 10(-9) M) reversed-phase high-performance liquid chromatography (HPLC) analysis of adenine nucleosides and nucleotides, especially in a biological matrix, is difficult using only ultraviolet detection. Derivatization coupled with fluorescence detection has been investigated as a means of enhancing sensitivity for the reversed-phase HPLC analysis of 2'-beta-fluoro-2',3'-dideoxyadenosine (F-ddA), an experimental, acid-stable, anti-AIDS drug. The reaction of chloroacetaldehyde with the adenine base has been employed to form fluorescent 1,N(6)-etheno derivatives of F-ddA and 5'-deoxyadenosine, which is used as an internal standard. These derivatives give an analytically useful fluorescence emission at 416 nm after excitation at 230, 265, or 275 nm. Derivatization, fluorescence detection and reversed-phase chromatography have been optimized for the analysis of nanomolar concentrations of F-ddA in human plasma. This method has potential for the measurement of F-ddA at low concentration and in limited volume samples from in vivo biological studies.

A pilot study of new approaches to teaching anatomy and pathology

PURPOSE

Minimally Invasive Surgery (MIS) has impacted patient care as well as medical training. New medical education opportunities have emerged with MIS. In this pilot study we explore the role of live, interactive MIS to augment and strengthen specific segments of the undergraduate medical curriculum.

METHODS

Laparoscopic cholecystectomy (LC) was selected to demonstrate upper abdominal anatomy and pathology. Second year medical students (n=100) in the course of their GI pathology classes attended live LC telesurgery-the telesurgery student group (TSG). Because of technical difficulties, a second class of medical students (n=90) was shown the tape of the MIS procedure one year later instead of the live surgery-the videotape surgery group (VSG). Background clinical information was provided by the program director and the durgeon. During the live and taped LC broadcast living anatomy was demonstrated and a diseased gallbladder was resected. TSG students were able to ask questions of the program director and the surgeon and vice versa using telesurgery technology. After the procedure, the surgeon met with the students for further discussion. VSG students were able to ask questions of the program director during and after the program. Both groups of students completed a pre- and posttest using remote audience responders. Students' responses from the two groups were compared for selected test and evaluation items.

RESULTS

Pre-test (Cronbach's alpha=.10) and post-test (Cronbach's alpha =.28) data were obtained from 73 students in the TSG and.22 and.54 respectively from 69 students in the VSG. A significant increase in laparoscopic anatomy knowledge was observed from pretest to posttest for the VSG (31-55%) and from the TSG (30-61%). The majority of VSG students (68%) indicated the method used to teach was outstanding, and 87% indicated that the program was outstanding in keeping their interest. This is contrasted with only 24% of the TSG group responding that the teaching method was outstanding, and 41% indicated that the program was outstanding in keeping their interest.

CONCLUSIONS

Medical students can productively be exposed to surgical methods and living anatomy using telesurgery. The high regard the TSG students had for this program suggests that it can be used effectively to teach and inspire medical students. The positive results have encouraged us to have a backup instructional method such as a tape of the MIS procedure, it apparently does not have the positive impact of live surgery.

Determination of lodenosine and its major metabolite in human plasma by liquid chromatography/electrospray ionization tandem mass spectrometry

A sensitive and selective method for the determination of 2'-beta-fluoro-2',3'-dideoxyadenosine (lodenosine, F-ddA), an experimental anti-AIDS drug, and its major metabolite, 2'-beta-fluoro-2',3'-dideoxyinosine (F-ddI), in human plasma was developed and validated. The procedure employs two internal standards and a simple ultrafiltration step followed by chromatography on a Betasil C(18) minibore column. An in-line valve is used to remove salts before reaching the ion source. Detection is by electrospray ionization tandem mass spectrometry with selected reaction monitoring. The method has a limit of quantitation of 4 ng ml(-1) (16 nM) for F-ddA and 8 ng ml(-1) (32 nM) for F-ddI with a linear range up to 2000 ng ml(-1) (7.9 microM) for each. Predicted concentrations from a three-day validation study were within 5% of the nominal values for F-ddA and 16% for F-ddI. Intra- and inter-assay precision, as measured by relative standard deviation, was 13% or better for both compounds. To achieve good reproducibility, many variables related to the electrospray ionization were optimized for both precision and sensitivity. The method was successfully employed to analyze samples and evaluate plasma pharmacokinetics from a Phase I clinical trial.

Minilaparoscopically assisted placement of ventriculoperitoneal shunts

BACKGROUND

Ventriculoperitoneal (VP) shunting remains the preferred treatment for hydrocephalus. Laparoscopic techniques to aid in the placement of the peritoneal portion of the catheter have been reported previously. We describe a minilaparoscopic VP shunt (MLVPS) insertion technique that facilitates directed placement of the peritoneal portion of the catheter in most patients, including those with obese abdomens previously subjected to surgery. In this study we review our experience with MLVPS placement.

METHODS

All cases of MLVPS insertions at the University of Kentucky Medical Center and Lexington VA Hospital performed between February 1998 and March 1999 were reviewed retrospectively. A total of 27 patients (13 males and 14 females) ranging in age from 4 to 81 years (mean, 41 years) underwent VP shunting. The MLVPS insertion was performed via a 2-mm laparoscope and a separate 2-mm incision for catheter insertion using a venous introducer kit. In patients who had prior abdominal surgery, a 5-mm direct-view trocar was used.

RESULTS

The MLVPS procedure was successful in 27 patients (100%). The mean number of prior shunts was 2 (range, 0-28). Of the 27 patients, 16 (59%) had undergone previous abdominal surgery. The mean operative time was 76 min (range, 19-155 min). There were no intra- or postoperative complications, and no mortalities. The follow-up period extended from 1 to 12 months.

CONCLUSIONS

Findings show MLVPS placement to be safe and feasible. It allows accurate, directed placement of the VP shunt with a 2-mm laparoscope and a second 2-mm incision for shunt insertion. The procedure is associated with reduced trauma to the abdominal wall and minimal postoperative ileus. Long-term follow-up assessment of shunt function is planned.

2'-beta-fluoro-2',3'-dideoxyadenosine, lodenosine, in rhesus monkeys: plasma and cerebrospinal fluid pharmacokinetics and urinary disposition

2'-beta-Fluoro-2',3'-dideoxyadenosine (F-ddA, lodenosine) is a nucleoside analog that was rationally designed as a more chemically and enzymatically stable anti-AIDS drug than its parent compound 2', 3'-dideoxyadenosine or didanosine. Plasma and cerebrospinal fluid (CSF) pharmacokinetics of this compound and its major metabolite, 2'-beta-fluoro-2',3'-dideoxyinosine (F-ddI), were studied in three rhesus monkeys after a single 20 mg/kg dose administered as an i.v. push. F-ddA exhibited a mean residence time of 0.17 h in plasma and its plasma concentration time profile appeared to be biexponential. The majority of plasma exposure was from F-ddI, with a mean parent drug area under the curve (AUC) to metabolite AUC ratio of 0.16. CSF levels were low, with a mean CSF AUC to plasma AUC ratio of 0.068, with approximately one-quarter of this exposure in CSF due to unchanged drug. Urinary excretion accounted for half of the drug administered with the majority recovered as the metabolite, F-ddI. In a separate experiment, one monkey received a 20 mg/kg i.v. dose of F-ddI. The total dideoxynucleoside plasma exposure was greater than it was after administration of F-ddA; however, the CSF AUC to plasma AUC ratio was a factor of 4 lower (0.017). Thus, F-ddA central nervous system penetration is at least comparable to that of didanosine, indicating that this experimental drug has potential as an addition to currently approved AIDS therapies.

Determination of 2'-beta-fluoro-2',3'-dideoxyadenosine, an experimental anti-AIDS drug, in human plasma by high-performance liquid chromatography

2'-Beta-fluoro-2',3'-dideoxyadenosine (F-ddA, lodenosine) is an experimental anti-AIDS drug currently being evaluated in a Phase I clinical trial. A simple and specific HPLC method with UV detection, suitable for use in clinical studies, has been developed to determine both F-ddA and its deaminated catabolite, 2'-beta-fluoro-2',3'-dideoxyinosine (F-ddI) in human plasma. After inactivation of plasma HIV by 0.5% Triton X-100, the compounds of interest are isolated and concentrated using solid-phase extraction. Processed samples are separated by use of a pH 4.8 buffered methanol gradient on a reversed-phase phenyl column. The method has a linear range of 0.05-5 microg/ml (0.2-20 microM) and intra-assay precision is better than 8%. Analyte recovery is quantitative and plasma protein binding is minimal. In addition, drug and metabolite levels measured in Triton-treated human plasma remain stable for at least 5 months when samples are stored frozen without further treatment. Compound concentrations determined after samples are processed and then frozen for up to 1 month before analysis are also unchanged.

Lipophilic, acid-stable, adenosine deaminase-activated anti-HIV prodrugs for central nervous system delivery. 3. 6-Amino prodrugs of 2'-beta-fluoro-2',3'-dideoxyinosine

A series of 6-substituted amino analogs of 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl) purines (F-ddN) has been synthesized and characterized with the objective of finding compounds which might be superior to existing drugs for the treatment of HIV in the central nervous system. These compounds are intended to be more lipophilic than the currently approved anti-HIV drugs for better blood-brain barrier penetration. Subsequent adenosine deaminase (ADA)-catalyzed hydrolysis of these prodrugs in the brain is expected to produce the anti-HIV agent, 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl)hypoxanthine (F-ddI). The new compounds, synthesized from the corresponding 6-chloro analog, include F-ddN which contain methylamino, ethylamino, dimethylamino, hydroxylamino, methoxyamino, benzyloxyamino, hydrazino, and nitro substituents in the 6-position. The 6-nitro analog was isolated as an unexpected product during the preparation of the 6-chloro derivative. Among the analogs with anti-HIV activity, the ethylamino and dimethylamino compounds are ca. 100 times more lipophilic than ddI or F-ddI. As expected, 2'-fluoro substitution protects the compounds from acid-catalyzed glycosylic cleavage. Only the hydroxylamino and nitro analogs underwent any nonenzymatic hydrolysis at pH 1.0 or 7.4. This reaction, however, results in hydrolysis of the group in the 6-position rather than glycosylic bond cleavage. ADA catalyzes the hydrolysis of the 6-substituents at rates which vary from slightly slower (NO2, 1.7x) to much slower (NHEt, 5000x) than F-ddA. The 6-dimethylamino analog is the only compound which possesses anti-HIV activity (ED50 18 microM) without ADA hydrolysis. With the exception of the two inactive alkoxyamino compounds, the other prodrugs exhibited cellular protection in the HIV-1/PHA-PBM system with IC50 potencies of 7-40 microM.

Acute cardiotoxicity of the Anti-HIV dideoxynucleoside, F-ddA, in the rat

2'-beta-Fluoro-2',3'-dideoxyadenosine (F-ddA), an acid-stable, purine dideoxynucleoside with in vitro anti-HIV activity, has been selected by the NCI as a clinical trial candidate. A recent report that high, single doses of F-ddA produce cardiotoxicity in rats prompted the present investigation whose objective was to quantitate this effect and establish a relationship between this toxicity and F-ddA plasma concentrations. Microscopic examination of cardiac tissues for degenerative lesions established the effects of F-ddA and ddA on three iv schedules [daily x 1(2.5-250 mg/kg); daily x 5(125, 250 mg/kg), and BID x 1 (250 mg/kg)] as well as one oral schedule [BID x 1 (500 mg/kg) using 8- to 12-week old female Sprague-Dawley rats. For both F-ddA and ddA, the group mean severity of the cardiac lesions was dose-dependent and proportional to the measured plasma concentrations of the undeaminated parent drugs. F-ddI and ddI, were essentially nontoxic in this study (iv, 250 mg/kg, daily x 1 and daily x 5), since plasma concentrations exceeding 2 mM produced only minimal cardiac lesions. The cardiomyopathy of F-ddA was minimal to mild for all iv doses except 250 mg/kg (daily x 1) and usually was greater than that of ddA at any given dose. This is a consequence of the fact that F-ddA is deaminated 20 times more slowly than ddA, resulting in higher plasma concentrations of F-ddA relative to ddA at any given time for any given dose. Neither F-ddA nor ddA was more cardiotoxic on a repeated iv schedule (daily x 5) than when administered only once, suggesting that rat cardiotoxicity is related Cmax rather than total exposure. In this most sensitive species, the formation of cardiac lesions above the background level is associated with i.v. F-ddA administration when the F-ddA plasma concentration approaches 300 microM, 30-50 times the anticipated therapeutic level in humans.

Occult tooth fragments spontaneously extruded after six months

Fracture of one or more teeth is a frequent complication of trauma to the oral cavity. Broken teeth that are not accounted for are often presumed to be swallowed or lost. We report a case of fracture of incisors that were not located on physical examination following the trauma but were discovered six months later as hard, perforating papulonodules on the lower lip.

Simultaneous measurement of the cell-differentiating agent hexamethylene bisacetamide and its metabolites by gas chromatography

Hexamethylene bisacetamide (HMBA) is a potent in vitro differentiating agent that has clinical potential as an anticancer drug both as a single agent and as a component of combination therapy. A sensitive and efficient GC method for the isolation, derivatization, and measurement of both HMBA and its two major metabolites in plasma and urine in a single analysis is described. In situ carbamylation of the biological sample with diethylpyrocarbonate forms the urethane derivative of the basic N-acetyl diaminohexane metabolite and allows analyte isolation and concentration by solid-phase extraction. Subsequent formation of the n-butyl ester of 6-acetamidohexanoic acid, the major metabolite, provides a derivatized biological extract that can be rapidly analyzed by temperature-programmed GC. The quantitative extraction and the efficient derivatization steps provide a limit of quantitation of 0.05 mM (10 micrograms/ml) for all analytes with a precision better than 8% for the range of in vitro activity (0.1-2.0 mM). This method is amenable to automation and is well-suited for the analysis of clinical samples.