A western trauma association multicenter comparison of mesh versus non-mesh repair of blunt traumatic abdominal wall hernias

BACKGROUND

Blunt traumatic abdominal wall hernias (TAWH) occur in <1 % of trauma patients. Optimal repair techniques, such as mesh reinforcement, have not been studied in detail. We hypothesize that mesh use will be associated with increased surgical site infections (SSI) and not improve hernia recurrence.

MATERIALS AND METHODS

A secondary analysis of the Western Trauma Association blunt TAWH multicenter study was performed. Patients who underwent TAWH repair during initial hospitalization (1/2012-12/2018) were included. Mesh repair patients were compared to primary repair patients (non-mesh). A logistic regression was conducted to assess risk factors for SSI.

RESULTS

157 patients underwent TAWH repair during index hospitalization with 51 (32.5 %) having mesh repair: 24 (45.3 %) synthetic and 29 (54.7 %) biologic. Mesh patients were more commonly smokers (43.1 % vs. 22.9 %, p = 0.016) and had a larger defect size (10 vs. 6 cm, p = 0.003). Mesh patients had a higher rate of SSI (25.5 % vs. 9.5 %, p = 0.016) compared to non-mesh patients, but a similar rate of recurrence (13.7 % vs. 10.5%, p = 0.742), hospital length of stay (LOS), and mortality. Mesh use (OR 3.66) and higher ISS (OR 1.06) were significant risk factors for SSI in a multivariable model.

CONCLUSION

Mesh was used more frequently in flank TAWH and those with a larger defect size. Mesh use was associated with a higher incidence and risk of SSI but did not reduce the risk of hernia recurrence. When repairing TAWH mesh should be employed judiciously, and prospective randomized studies are needed to identify clear indications for mesh use in TAWH.

An initiative to assess and improve the resources and patient care processes used among Chest Wall Injury Society collaborative centers (CWIS-CC2)

BACKGROUND

Over the last two decades, the acute management of rib fractures has changed significantly. In 2021, the Chest Wall injury Society (CWIS) began recognizing centers who epitomize their mission as CWIS Collaborative Centers (CWIS-CC). The primary aim of this study was to determine the resources, surgical expertise, access to care, and institutional support that are present among centers.

METHODS

A survey was performed including all CWIS-CC evaluating the resources available at their hospital for the treatment of patients with chest wall injury. Data about each Chest Wall Injury Center (CWIC) care process, availability of resources, institutional support, research support, and educational offerings were recorded.

RESULTS

Data was collected from 20 trauma centers resulting in an 80% response rate. These trauma centers were made up of 5 international and 15 US based trauma centers. Eighty percent (16/20) have dedicated care team members for the evaluation and management of rib fractures. Twenty-five percent (5/20) have a dedicated rib fracture service with a separate call schedule. Staffing for chest wall injury clinics consists of a multidisciplinary team: with attending surgeons in all clinics, 80%(8/10) with APPs and 70%(7/10) with care coordinators. Forty percent(8/20) of centers have dedicated rib fracture research support and 35%(7/20) have SSRF-related grants. Forty percent (8/20) of centers have marketing support and 30%(8/20) have a web page support to bring awareness to their center. At these trauma centers, a median of 4(1-9) surgeons perform surgical stabilization of rib fractures (SSRF). In the majority of trauma centers the trauma surgeons perform SSRF.

CONCLUSIONS

Considerable similarities and differences exist within these CWIS collaborative centers. These differences in resources are hypothesis generating in determining the optimal CWIC. These findings may generate several patient care and team process questions to optimize patient care, patient experience, provider satisfaction, research productivity, education, and outreach.

LEVEL OF EVIDENCE

IV Economic & Value-Based Evaluations.

Intercostal nerve cryoablation during surgical stabilization of rib fractures decreases post-operative opioid use, ventilation days, and intensive care days

BACKGROUND

Intercostal nerve cryoablation is an adjunctive measure that has demonstrated pain control, decrease in opioid consumption, and decrease in hospital length of stay (LOS) in patients who undergo surgical stabilization of rib fractures (SSRF).

METHODS

SSRF patients from January 2015 to September 2021 were retrospectively compared. All patients received multimodal pain regimens post-operatively and the independent variable was intraoperative cryoablation.

RESULTS

241 patients met inclusion criteria. 51 (21%) underwent intra-operative cryoablation during SSRF and 191 (79%) did not. Patients with standard treatment consumed 9.4 more daily MME (p = 0.035), consumed 73 percent more post-operative total MME (p = 0.001), spent 1.55 times as many days in the intensive care unit (p = 0.013), and spent 3.8 times as many days on the ventilator than patients treated with cryoablation, respectively. Overall hospital LOS, operative case time, pulmonary complications, MME at discharge, and numeric pain scores at discharge were no different (all p>0.05).

CONCLUSION

Intercostal nerve cryoablation during SSRF is associated with fewer ventilator days, ICU LOS, total post-operative, and daily opioid use without increasing time in the operating room or perioperative pulmonary complications.

Timing of venous thromboembolism chemoprophylaxis using objective hemoglobin criteria in blunt solid organ injury

BACKGROUND

The purpose of this study was to evaluate the safety and efficacy of early venous thromboembolism (VTE) chemoprophylaxis following blunt solid organ injury.

METHODS

A retrospective review of patients was performed for patients with blunt solid organ injury between 2009-2019. Enoxaparin was initiated when patients had <1g/dl Hemoglobin decline over a 24 h period. These patients were then categorized by initiation: ≤48 h and >48 h.

RESULTS

There were 653 patients: 328 (50.2%) <48 h and 325 (49.8%) ≥48 h. Twenty-nine (4.4%) developed VTE. Patients in ≥48 h group suffered more frequent VTE events (6.5% vs 2.4%, p = 0.021). Non-operative failure occurred in 6 patients (1.9%) in ≥48 h group, and 5 patients (1.5%) < 48 h group. Blood transfusion following chemophrophylaxis initiation was required in 69 (21.3%) in ≥48 h group, and 46 (14.0%) in < 48 h group, occurring similarly between groups (p=0.021).

CONCLUSION

Stable hemoglobin in the first 24 h is an efficacious, objective measure that allows early initiation of VTE chemoprophylaxis in solid organ injury. This practice is associated with earlier initiation of and fewer VTE events.

Risk factors for recurrence in blunt traumatic abdominal wall hernias: A secondary analysis of a Western Trauma association multicenter study

BACKGROUND

Few studies have investigated risk factors for recurrence of blunt traumatic abdominal wall hernias (TAWH).

METHODS

Twenty trauma centers identified repaired TAWH from January 2012 to December 2018. Logistic regression was used to investigate risk factors for recurrence.

RESULTS

TAWH were repaired in 175 patients with 21 (12.0%) known recurrences. No difference was found in location, defect size, or median time to repair between the recurrence and non-recurrence groups. Mesh use was not protective of recurrence. Female sex, injury severity score (ISS), emergency laparotomy (EL), and bowel resection were associated with hernia recurrence. Bowel resection remained significant in a multivariable model.

CONCLUSION

Female sex, ISS, EL, and bowel resection were identified as risk factors for hernia recurrence. Mesh use and time to repair were not associated with recurrence. Surgeons should be mindful of these risk factors but could attempt acute repair in the setting of appropriate physiologic parameters.

Emergencies do not shut down during a pandemic: COVID pandemic impact on Acute Care Surgery volume and mortality at a level I trauma center

BACKGROUND

The aim of this study was to evaluate the impact of the COVID-19 pandemic on volume and outcomes of Acute Care Surgery patients, and we hypothesized that inpatient mortality would increase due to COVID+ and resource constraints.

METHODS

An American College of Surgeons verified Level I Trauma Center's trauma and operative emergency general surgery (EGS) registries were queried for all patients from Jan. 2019 to Dec. 2020. April 1st, 2020, was the demarcation date for pre- and during COVID pandemic. Primary outcome was inpatient mortality.

RESULTS

There were 14,460 trauma and 3091 EGS patients, and month-over-month volumes of both remained similar (p > 0.05). Blunt trauma decreased by 7.4% and penetrating increased by 31%, with a concomitant 25% increase in initial operative management (p < 0.001). Despite this, trauma (3.7%) and EGS (2.9-3.0%) mortality rates remained stable which was confirmed on multivariate analysis; p > 0.05. COVID + mortality was 8.8% and 3.7% in trauma and EGS patients, respectively.

CONCLUSION

Acute Care Surgeons provided high quality care to trauma and EGS patients during the pandemic without allowing excess mortality despite many hardships and resource constraints.

Safe endovascular retrieval of a vena cava filter after duodenal perforation

The use of vena cava filters (VCF) is a common procedure utilized in the prevention of pulmonary embolism (PE), yet VCFs have some significant and known complications, such as strut penetration and migration. Deep vein thrombosis (DVT) and PE remain a major cause of morbidity and mortality in the United States. It is estimated that as many as 900,000 individuals are affected by these each year with estimates suggesting that nearly 60,000–100,000 Americans die of DVT/PE each year. Currently, the preferred treatment for DVT/PE is anticoagulation. However, if there are contraindications to anticoagulation, an inferior vena cava (IVC) filter can be placed. These filters have both therapeutic and prophylactic indications. Therapeutic indications (documented thromboembolic disease) include absolute or relative contraindications to anticoagulation, complication of anticoagulation, failure of anticoagulation, propagation/progression of DVT during therapeutic anticoagulation, PE with residual DVT in patients with further risk of PE, free-floating iliofemoral IVC thrombus, and severe cardiopulmonary disease and DVT. There are also prophylactic indications (no current thromboembolic disease) for these filters. These include severe trauma without documented PE or DVT, closed head injury, spinal cord injury, multiple long bone fractures, and patients deemed at high risk of thromboembolic disease (immobilized or intensive care unit). Interruption of the IVC with filters has long been practiced and is a procedure that can be performed on an outpatient basis. There are known complications of filter placement, which include filter migration within the vena cava and into various organs, as well as filter strut fracture. This case describes a 66-year-old woman who was found to have a filter migration and techniques that were utilized to remove this filter.

Management of blunt traumatic abdominal wall hernias: A Western Trauma Association multicenter study

BACKGROUND

Blunt traumatic abdominal wall hernias (TAWH) occur in approximately 15,000 patients per year. Limited data are available to guide the timing of surgical intervention or the feasibility of nonoperative management.

METHODS

A retrospective study of patients presenting with blunt TAWH from January 2012 through December 2018 was conducted. Patient demographic, surgical, and outcomes data were collected from 20 institutions through the Western Trauma Association Multicenter Trials Committee.

RESULTS

Two hundred and eighty-one patients with TAWH were identified. One hundred and seventy-six (62.6%) patients underwent operative hernia repair, and 105 (37.4%) patients underwent nonoperative management. Of those undergoing surgical intervention, 157 (89.3%) were repaired during the index hospitalization, and 19 (10.7%) underwent delayed repair. Bowel injury was identified in 95 (33.8%) patients with the majority occurring with rectus and flank hernias (82.1%) as compared with lumbar hernias (15.8%). Overall hernia recurrence rate was 12.0% (n = 21). Nonoperative patients had a higher Injury Severity Score (24.4 vs. 19.4, p = 0.010), head Abbreviated Injury Scale score (1.1 vs. 0.6, p = 0.006), and mortality rate (11.4% vs. 4.0%, p = 0.031). Patients who underwent late repair had lower rates of primary fascial repair (46.4% vs. 77.1%, p = 0.012) and higher rates of mesh use (78.9% vs. 32.5%, p < 0.001). Recurrence rate was not statistically different between the late and early repair groups (15.8% vs. 11.5%, p = 0.869).

CONCLUSION

This report is the largest series and first multicenter study to investigate TAWHs. Bowel injury was identified in over 30% of TAWH cases indicating a significant need for immediate laparotomy. In other cases, operative management may be deferred in specific patients with other life-threatening injuries, or in stable patients with concern for bowel injury. Hernia recurrence was not different between the late and early repair groups.

LEVEL OF EVIDENCE

Therapeutic/care management, Level IV.

Emergency General Surgery Regionalization: Retrospective Cohort Study of Emergency General Surgery Patients at a Tertiary Care Center

BACKGROUND

Emergency general surgery (EGS) patients presenting at tertiary care hospitals may bypass local hospitals with adequate resources. However, many tertiary care hospitals frequently operate at capacity. We hypothesized that understanding patient geographic origin could identify opportunities for enhanced system triage and optimization and be an important first step for EGS regionalization and care coordination that could potentially lead to improved utilization of resources.

METHODS

We analyzed patient zip code and categorized EGS patients who were cared for at our tertiary care hospital as potentially divertible if the southern region hospital was geographically closer to their home, regional hospital admission (RHA) patients, or local admission (LA) patients if the tertiary care facility was closer. Baseline characteristics and outcomes were compared for RHA and LA patients.

RESULTS

Of 14 714 EGS patients presenting to the tertiary care hospital, 30.2% were categorized as RHA patients. Overall, 1526 (10.4%) patients required an operation including 527 (34.5%) patients who were potentially divertible. Appendectomy and cholecystectomy comprised 66% of the operations for potentially divertible patients. Length of stay was not significantly different (P = .06) for RHA patients, but they did have lower measured short-term and long-term mortality when compared to their LA counterparts (P < .05).

CONCLUSIONS

EGS diagnoses and patient geocode analysis can identify opportunities to optimize regional operating room and bed utilization. Understanding where EGS patients are cared for and factors that influenced care facility will be critical for next steps in developing EGS regionalization within our system.

Attention to detail: A dedicated rib fracture consultation service leads to earlier operation and improved clinical outcomes

BACKGROUND

Surgical stabilization of rib fractures (SSRF) has been correlated with improved outcomes, including decreased length of stay (LOS). We hypothesized that an SSRF consultation service would increase the frequency of SSRF and improve outcomes.

METHODS

A prospective observational study was performed to compare outcomes before and after implementing an SSRF service. Primary outcome was time from admission to surgery; secondary outcomes included LOS, mortality and morphine milligram equivalents (MME) prescribed at discharge.

RESULTS

1865 patients met consultation criteria and 128 patients underwent SSRF. Mortality decreased (6.3% vs. 3%) and patients were prescribed fewer MME at discharge (328 MME vs. 124 MME) following implementation. For the operative cohort, time from admission to surgery decreased by 1.72 days and ICU LOS decreased by 2.6 days.

CONCLUSION

Establishment of an SSRF service provides a mechanism to maximize capture and evaluation of operative candidates, provide earlier intervention, and improve patient outcomes. Additional study to determine which elements and techniques are most beneficial is warranted.

LEVEL OF EVIDENCE

III.

Advancing the Use of Laparoscopy in Trauma: Repair of Intraperitoneal Bladder Injuries

Traumatic intraperitoneal bladder rupture (IBR) requires surgical repair. Traditionally performed via laparotomy, experience with laparoscopic bladder repair (LBR) after blunt trauma is limited. Benefits of laparoscopy include decreased length of stay (LOS), less pain, early return to work, fewer adhesions, and lower risk of incisional hernia. The aim of this series is to demonstrate the potential superiority of LBR in select trauma patients. This is a retrospective review performed of all IBR patients from 2008 to 2016. Demographics, clinical management, outcomes, and follow-up were compared between LBR and open bladder repair (OBR) patients. Twenty patients underwent OBR, and seven underwent LBR. There was no significant difference in gender, age, or Injury Severity Score. There were no deaths or reoperations in either group. Average hospital length of stay and ICU days were similar between groups. There was one patient with UTI and one with readmission in each group. There were two incisional hernias and two bowel obstructions in the OBR group, with one patient requiring operative intervention. No such complications occurred in the LBR group. LBR for traumatic IBR can be safely performed in select patients, even in those with multiple extra-abdominal injuries.

Advancing the Use of Laparoscopy in Trauma: Repair of Intraperitoneal Bladder Injuries

Traumatic intraperitoneal bladder rupture (IBR) requires surgical repair. Traditionally performed via laparotomy, experience with laparoscopic bladder repair (LBR) after blunt trauma is limited. Benefits of laparoscopy include decreased length of stay (LOS), less pain, early return to work, fewer adhesions, and lower risk of incisional hernia. The aim of this series is to demonstrate the potential superiority of LBR in select trauma patients. This is a retrospective review performed of all IBR patients from 2008 to 2016. Demographics, clinical management, outcomes, and follow-up were compared between LBR and open bladder repair (OBR) patients. Twenty patients underwent OBR, and seven underwent LBR. There was no significant difference in gender, age, or Injury Severity Score. There were no deaths or reoperations in either group. Average hospital length of stay and ICU days were similar between groups. There was one patient with UTI and one with readmission in each group. There were two incisional hernias and two bowel obstructions in the OBR group, with one patient requiring operative intervention. No such complications occurred in the LBR group. LBR for traumatic IBR can be safely performed in select patients, even in those with multiple extra-abdominal injuries.

Not a Routine Case, Why Expect the Routine Outcome? Quantifying the Infectious Burden of Emergency General Surgery Using the NSQIP

Emergent surgeries have different causes and physiologic patient responses than the same elective surgery, many of which are due to infectious etiologies. Therefore, we hypothesized that emergency cases have a higher risk of postoperative SSI than their elective counterparts. The ACS NSQIP database was queried from 2005 to 2016 for all cholecystectomies, ventral hernia repairs, and partial colectomies to examine common emergency and elective general surgery operations. Thirty-day outcomes were compared by emergent status. Any SSI was the primary outcome. There were 863,164 surgeries: 416,497 cholecystectomies, 220,815 ventral hernia repairs, and 225,852 partial colectomies. SSIs developed in 38,865 (4.5%) patients. SSIs increased with emergencies (5.3% vs 3.6% for any SSI). Postoperative sepsis (5.8% vs 1.5%), septic shock (4.7% vs 0.6%), length of stay (8.1 vs 2.9 days), and mortality (3.6% vs 0.4%) were increased in emergent surgery; P < 0.001 for all. When controlling for age, gender, BMI, diabetes, smoking, wound classification, comorbidities, functional status, and procedure on multivariate analysis, emergency surgery (odds ratio 1.15, 95% confidence interval 1.11–1.19) was independently associated with the development of SSI. Patients undergoing emergency general surgery experience increased rates of SSI. Patients and their families should be appropriately counseled regarding these elevated risks when consenting for emergency surgery.

Not a Routine Case, Why Expect the Routine Outcome? Quantifying the Infectious Burden of Emergency General Surgery Using the NSQIP

Emergent surgeries have different causes and physiologic patient responses than the same elective surgery, many of which are due to infectious etiologies. Therefore, we hypothesized that emergency cases have a higher risk of postoperative SSI than their elective counterparts. The ACS NSQIP database was queried from 2005 to 2016 for all cholecystectomies, ventral hernia repairs, and partial colectomies to examine common emergency and elective general surgery operations. Thirty-day outcomes were compared by emergent status. Any SSI was the primary outcome. There were 863,164 surgeries: 416,497 cholecystectomies, 220,815 ventral hernia repairs, and 225,852 partial colectomies. SSIs developed in 38,865 (4.5%) patients. SSIs increased with emergencies (5.3% vs 3.6% for any SSI). Postoperative sepsis (5.8% vs 1.5%), septic shock (4.7% vs 0.6%), length of stay (8.1 vs 2.9 days), and mortality (3.6% vs 0.4%) were increased in emergent surgery; P < 0.001 for all. When controlling for age, gender, BMI, diabetes, smoking, wound classification, comorbidities, functional status, and procedure on multivariate analysis, emergency surgery (odds ratio 1.15, 95% confidence interval 1.11-1.19) was independently associated with the development of SSI. Patients undergoing emergency general surgery experience increased rates of SSI. Patients and their families should be appropriately counseled regarding these elevated risks when consenting for emergency surgery.

“Death Knell” for Prophylactic Vena Cava Filters? A 20-Year Experience with a Venous Thromboembolism Guideline

The role of prophylactic vena cava filters (pVCFs) in trauma patients remains controversial. After 20 years of data collection and experience, we reviewed our venous thromboembolism guideline for the efficacy of pVCFs in preventing pulmonary embolism (PE). A retrospective cohort study was performed using our Level I trauma center registry from January 1997 thru December 2016. This population was then divided by the presence of pVCFs. Univariate analysis was performed comparing the incidence of PEs, deep vein thrombosis, and mortality between those with and without a pVCF. There were 35,658 patients identified, of whom 2 per cent (n = 847) received pVCFs. The PE rate was 0.4 per cent in both groups. The deep vein thrombosis rate for pVCFs was 3.9 per cent compared with 0.6 per cent in the no-VCF group ( P < 0.0001). Given that there was no difference in the rates of PEs between the cohorts, the subset of patients with a PE were analyzed by their risk factors. Only ventilator days > 3 were associated with a higher risk in the no-pVCF group (0.2 vs 1.5%, P = 0.033). pVCFs did not confer benefit reducing PE rate. In addition, despite their intended purpose, pVCFs cannot eliminate PEs in high-risk trauma patients, suggesting a lack of utility for prophylaxis in this population.

"Death Knell" for Prophylactic Vena Cava Filters? A 20-Year Experience with a Venous Thromboembolism Guideline

The role of prophylactic vena cava filters (pVCFs) in trauma patients remains controversial. After 20 years of data collection and experience, we reviewed our venous thromboembolism guideline for the efficacy of pVCFs in preventing pulmonary embolism (PE). A retrospective cohort study was performed using our Level I trauma center registry from January 1997 thru December 2016. This population was then divided by the presence of pVCFs. Univariate analysis was performed comparing the incidence of PEs, deep vein thrombosis, and mortality between those with and without a pVCF. There were 35,658 patients identified, of whom 2 per cent (n = 847) received pVCFs. The PE rate was 0.4 per cent in both groups. The deep vein thrombosis rate for pVCFs was 3.9 per cent compared with 0.6 per cent in the no-VCF group (P < 0.0001). Given that there was no difference in the rates of PEs between the cohorts, the subset of patients with a PE were analyzed by their risk factors. Only ventilator days > 3 were associated with a higher risk in the no-pVCF group (0.2 vs 1.5%, P = 0.033). pVCFs did not confer benefit reducing PE rate. In addition, despite their intended purpose, pVCFs cannot eliminate PEs in high-risk trauma patients, suggesting a lack of utility for prophylaxis in this population.

Returning from the acidotic abyss: Mortality in trauma patients with a pH < 7.0

INTRODUCTION

We hypothesized that a pH of <7.0 on presentation would correlate with almost universal mortality in trauma patients.

METHODS

A retrospective cohort study was performed on a Level I trauma center registry from 2013 to 2014. Hospital mortality was the primary outcome, which was compared by pH cohort (<7.0 or ≥7.0) using standard univariate statistics and multivariate logistic regression.

RESULTS

There were 593 patients included in the analysis: 66 in <7.0, 527 in ≥7.0. Mortality was 3× higher in the <7.0 pH cohort (62.1 vs. 20.3%; p < 0.0001), however there was no threshold for a pH below which there was 100% mortality. After controlling for these confounding variables, initial pH was found to be an independent predictor of inpatient mortality: pH < 7.0 (OR 6.33, 3.29-12.19; p < 0.0001).

CONCLUSION

This data indicates that while patients with severe acidosis are at increased risk for mortality, a pH < 7.0 is still recoverable in select cases.

Do not waste your time: straight to magnetic resonance imaging for pediatric burners and stingers

BACKGROUND

Permanent neurologic injury in pediatric patients with burner and stinger syndrome (BSS) is unlikely. This study aims to assess the feasibility of clinical observation without extensive radiologic workup in this selective population.

METHODS

A retrospective study was conducted of patients aged younger than 18 years evaluated at a level I trauma center from 2012 to 2014. Patients were grouped according to positive deficit (PD) or negative deficit (ND) upon physical examination. Demographics, clinical findings, and outcomes were analyzed.

RESULTS

Thirty patients (ND, n = 14; PD, n = 16) were evaluated for BSS, most often as a result of injurious football tackle. Age and length of stay were similar between groups. Injury Severity Score was lower in the ND group than the PD group (1.6 ± 1.2 vs 3.8 ± 3.1, respectively; P< .05). Cervical computed tomography was performed on 11 patients (78.6%) in the ND group and 15 patients (93.8%) in the PD group at considerable added cost, with only 1 positive result in the ND group and none in the PD group. Magnetic resonance imaging (MRI) revealed 2 positive findings in each group, and no surgical interventions were indicated. Ten ND (71.4%) and 12 PD (75%) patients reported complete resolution of symptoms at discharge (P> .05).

CONCLUSIONS

Children presenting with BSS experience temporary symptoms that resolve without surgical intervention. Magnetic resonance imaging identified more injuries than computed tomographic imaging; therefore, we suggest that management for BSS should include observation, serial neurologic examinations, and MRI evaluation as appropriate.

Errors in Administrative-Reported Ventilator-Associated Pneumonia Rates: Are Never Events Really So?

Ventilator-associated pneumonia (VAP) is a common problem in an intensive care unit (ICU), although the incidence is not well established. This study aims to compare the VAP incidence as determined by the treating surgical intensivist with that detected by the hospital Infection Control Service (ICS). Trauma and surgical patients admitted to the surgical critical care service were prospectively evaluated for VAP during a 5-month time period. Collected data included the surgical intensivist's clinical VAP (SIS-VAP) assessment using Centers for Disease Control and Prevention (CDC) VAP criteria. As part of the hospital's VAP surveillance program, these patients’ medical records were also reviewed by the ICS for VAP (ICS-VAP) using the same CDC VAP criteria. All patients suspected of having VAP underwent bronchioalveolar lavage (BAL). The SIS-VAP and ICS-VAP were then compared with BAL-VAP. Three hundred twenty-nine patients were admitted to the ICU during the study period. One hundred thirty-three were intubated longer than 48 hours and comprised our study population. Sixty-two patients underwent BAL evaluation for the presence of VAP on 89 occasions. SIS-VAP was diagnosed in 38 (28.5%) patients. ICS-VAP was identified in 11 (8.3%) patients ( P < 0.001). The incidence of VAP by BAL criteria was 23.3 per cent. When compared with BAL, SIS-VAP had 61.3 per cent sensitivity and ICS-VAP had 29 per cent sensitivity. VAP rates reported by hospital administrative sources are significantly less accurate than physician-reported rates and dramatically underestimate the incidence of VAP. Proclaiming VAP as a never event for critically ill for surgical and trauma patients appears to be a fallacy.

Errors in administrative-reported ventilator-associated pneumonia rates: are never events really so?

Ventilator-associated pneumonia (VAP) is a common problem in an intensive care unit (ICU), although the incidence is not well established. This study aims to compare the VAP incidence as determined by the treating surgical intensivist with that detected by the hospital Infection Control Service (ICS). Trauma and surgical patients admitted to the surgical critical care service were prospectively evaluated for VAP during a 5-month time period. Collected data included the surgical intensivist's clinical VAP (SIS-VAP) assessment using Centers for Disease Control and Prevention (CDC) VAP criteria. As part of the hospital's VAP surveillance program, these patients' medical records were also reviewed by the ICS for VAP (ICS-VAP) using the same CDC VAP criteria. All patients suspected of having VAP underwent bronchioalveolar lavage (BAL). The SIS-VAP and ICS-VAP were then compared with BAL-VAP. Three hundred twenty-nine patients were admitted to the ICU during the study period. One hundred thirty-three were intubated longer than 48 hours and comprised our study population. Sixty-two patients underwent BAL evaluation for the presence of VAP on 89 occasions. SIS-VAP was diagnosed in 38 (28.5%) patients. ICS-VAP was identified in 11 (8.3%) patients (P < 0.001). The incidence of VAP by BAL criteria was 23.3 per cent. When compared with BAL, SIS-VAP had 61.3 per cent sensitivity and ICS-VAP had 29 per cent sensitivity. VAP rates reported by hospital administrative sources are significantly less accurate than physician-reported rates and dramatically underestimate the incidence of VAP. Proclaiming VAP as a never event for critically ill for surgical and trauma patients appears to be a fallacy.

Structure of human prostasin, a target for the regulation of hypertension

Prostasin (also called channel activating protease-1 (CAP1)) is an extracellular serine protease implicated in the modulation of fluid and electrolyte regulation via proteolysis of the epithelial sodium channel. Several disease states, particularly hypertension, can be affected by modulation of epithelial sodium channel activity. Thus, understanding the biochemical function of prostasin and developing specific agents to inhibit its activity could have a significant impact on a widespread disease. We report the expression of the prostasin proenzyme in Escherichia coli as insoluble inclusion bodies, refolding and activating via proteolytic removal of the N-terminal propeptide. The refolded and activated enzyme was shown to be pure and monomeric, with kinetic characteristics very similar to prostasin expressed from eukaryotic systems. Active prostasin was crystallized, and the structure was determined to 1.45 A resolution. These apoprotein crystals were soaked with nafamostat, allowing the structure of the inhibited acyl-enzyme intermediate structure to be determined to 2.0 A resolution. Comparison of the inhibited and apoprotein forms of prostasin suggest a mechanism of regulation through stabilization of a loop which interferes with substrate recognition.

Induction and maintenance of ethanol self-administration in cynomolgus monkeys (Macaca fascicularis): long-term characterization of sex and individual differences

BACKGROUND

Investigations of oral ethanol self-administration in nonhuman primates have revealed important parallels with human alcohol use and abuse, yet many fundamental questions concerning the individual risk to, and the biological basis of, excessive ethanol consumption remain unanswered. Moreover, many conditions of access to ethanol in nonhuman primate research are largely unexplored. This set of experiments extends within- and across-session exposure to ethanol to more fully characterize individual differences in oral ethanol self-administration.

METHODS

Eight male and eight female adult cynomolgus monkeys (Macaca fascicularis) were exposed to daily oral ethanol self-administration sessions for approximately 9 months. During the first 3 months, a fixed-time (FT) schedule of food delivery was used to induce the consumption of an allotted dose of ethanol in 16-hr sessions. Subsequently, the FT schedule was suspended, and ethanol was available ad libitum for 6 months in 16- or 22-hr sessions.

RESULTS

Cynomolgus monkeys varied greatly in their propensity to self-administer ethanol, with sex and individual differences apparent within 10 days of ethanol exposure. Over the last 3 months of ethanol access, individual average ethanol intakes ranged from 0.6 to 4.0 g/kg/day, resulting in blood ethanol concentrations from 5 to 235 mg/dl. Males drank approximately 1.5-fold more than females. In addition, heavy-, moderate-, and light-drinking phenotypes were identified by using daily ethanol intake and the percentage of daily calories obtained from ethanol as criteria.

CONCLUSIONS

Cynomolgus monkeys displayed a wide intersubject range of oral ethanol self-administration with a procedure that used a uniform and prolonged induction that restricted early exposure to ethanol and subsequently allowed unlimited access to ethanol. There were sex and stable individual differences in the propensity of monkeys to consume ethanol, indicating that this species will be important in characterizing risk factors associated with heavy-drinking phenotypes.

Photographic analysis of facial changes associated with maxillary expansion

Previous studies on the effects of surgical and rapid palatal expansion have been largely based on general skeletal and dental findings ascertained from radiographs and casts. The aim of this study was to measure and compare the soft tissue changes of the face during the expansion process and to determine the stability of any changes 1 year later. The sample consisted of 44 patients with unilateral or bilateral posterior crossbites. Twenty-four of the patients required a surgically assisted expansion procedure, and a second group of 20 patients were treated with orthopedic expansion. Ten measurements were made from standardized frontal facial photographic slides at 5 intervals of treatment: initial, bond appliance, stop expansion, debond appliance, and 1 year retention. Differences over time between the surgical and nonsurgical groups were analyzed by a 2 way multivariate analysis of variance (MANOVA) and post hoc t tests. Differences between initial and 1 year retention were found in the nasal widths (P <.001) of both surgical and nonsurgical groups. Other significant changes and trends were discussed.

Confirmation of nasogastric tube placement by colorimetric indicator detection of carbon dioxide: a preliminary report

BACKGROUND

Inadvertent insertion of nasogastric tubes into the trachea and distal airways is reported to range from 0.3% to 15% of insertions. Critically ill, mechanically ventilated patients are at a higher risk for such complications, some of which can be fatal.

OBJECTIVE

This preliminary prospective clinical investigation was designed to determine whether a colorimetric carbon dioxide (CO2) indicator device (Easy-Cap, Nellcor, Inc., Hayward, CA) attached to the proximal end of a small bore feeding tube (FT) would reliably discriminate between those tubes passed into the airways and those passed into the alimentary tract.

METHODS

Ten critically ill, mechanically ventilated trauma patients requiring a FT insertion were evaluated. An Easy-Cap device was adapted to the proximal port of each FT. Each patient had one tube inserted per the nasogastric route and then another through the endotracheal tube while the Easy-Cap was observed for color changes consistent with the presence of CO2.

RESULTS

All transtracheal insertions showed immediate and unambiguous color changes consistent with the presence of CO2. None of the nasogastric insertions resulted in indicator color changes and all were confirmed with radiography (sensitivity 100%, specificity 100%, accuracy 100%).

CONCLUSIONS

This preliminary report suggests colorimetric CO2 detection accurately and reliably identifies transtracheal FT insertion.

Fast measurements of transmission of erythema effective irradiance through clothing fabrics

For efficiently measuring ultraviolet transmission through clothing materials for a large number of samples, an automated measuring system with a broad-band method has been built and calibrated against a spectroradiometer based instrument. The apparatus can be used to test 60 samples in 25 min. A selection of clothing materials of known composition, weave, color and state have been tested, using the broad band method and the automated measuring system together with a solar ultraviolet simulator. Variations of about eleven times for different weave structure, about two times in the ultraviolet transmittance for different colors, and about 20 times for some stretched samples were observed. For wet conditions, an increment in ultraviolet transmittance for cotton and lycra materials and a decrement for polyester and polyester(65%)/cotton(35%) were also observed.

UV-B radiometry and dosimetry for solar measurements

Biologically effective irradiance or dose of solar UV radiation was determined using a spectroradiometer, two broadband radiometers and two types of passive UV-dosimeters. The absolute erythema irradiance and the actinic irradiance were calculated from the solar spectrum measured with the spectroradiometer. It was demonstrated that the erythema irradiance is proportional to the actinic irradiance of solar radiation. The erythema irradiance was also determined using the two broadband radiometers which utilize a filter transmitting erythema spectra. Personal UV-dosimeters such as polysulphone and CR-39 were used to determine the erythema dose for a selected period of time. These results were used to estimate the accuracy of the broadband radiometers and UV-dosimeters. It was found that the results obtained from the broadband radiometers deviate from the absolute erythema irradiance by less than 20% during clear days between the hours of 11:00 and 13:00 Eastern Standard Time (EST) in Australia. The assessment of the erythema dose using passive dosimeters such as polysulphone and CR-39 could introduce an error as high as 40% if the calibration was not performed before undertaking experimental measurements.

Computer image analysis of pigmented skin lesions

To assist in the distinction of melanoma from benign pigmented lesions, an imaging system was developed, comprising a frame grabber, a microcomputer, a colour video camera and flash lighting with red, green and infrared filters. Over an 18-month period, video images of 70 unselected pigmented lesions for which complete diagnostic data were available, were successfully captured using the camera. Analysis software extracted features relevant to the size, colour, shape and boundary of each lesion, and these features were correlated with clinical and histological characteristics on which standard diagnoses of skin tumours are based. For discriminant analysis based on image analysis measurements, equal probabilities were assigned to three specified diagnostic groups, namely melanoma, naevi and 'other', and four of five melanomas were correctly classified when infrared data were included. However when infrared measurements were omitted, all five melanomas were correctly classified, and the overall accuracy of classification of pigmented lesions was 71%. This system holds promise as an aid in the clinical distinction of melanoma from benign pigmented skin lesions.

The Masters Degree in Medical Physics at Queensland University of Technology--14 years on

In 1975, the Masters Degree in Medical Physics was first made available at the Queensland Institute of Technology (now Queensland University of Technology, QUT), and is offered on both a part time and full time basis. An option for a Graduate Diploma award after completion of the in-house course work stage is available. The research project may be undertaken either in Brisbane or elsewhere. Such projects have been undertaken in Perth, Hong Kong, Sydney, etc. It is a broad based program, embracing activities of current professional importance while including aspects which have potential importance. Recognition that medical physics is a dynamic speciality ensures that the content of the program is kept under continuous review, and changes made as required. It is of interest to observe that of graduates from the course, approximately 50% have moved into the hospitals and private medical research, 11% into government health departments, 16% into the mining industry, 9% into tertiary education, and 14% into non medical or sales areas. Many have gained senior positions in their selected vocations. The success of the program in providing a useful professional person is due in no small measure to the collaboration of many dedicated professionals in the field. This collaboration relates to informal and formal contact between academic staff and students within the Physics Department, and personnel in hospitals, public health establishments and industry.

Chronic lead nephropathy in Queensland: alternative methods of diagnosis

Indices of past lead absorption were measured and compared in patients with chronic renal failure from many causes, including some with chronic lead nephropathy. X-ray fluorescence (XRF) yielded finger bone lead concentrations by a new in vivo method. These correlated significantly with excess urinary lead following calcium di-sodium EDTA (ethylenediamine tetra-acetate) and erythrocyte lead concentration. Discriminant function analysis demonstrated that the patients in the study could be separated into two groups without any reference to the EDTA lead excretion test using the following variables, all of which contributed significantly to the discrimination. In order of importance, these were: a childhood history of acute lead poisoning, a history of gout, a family history of gout and detectable XRF finger bone lead. Although the XRF finger bone lead measurement is convenient and non-invasive, its lack of sensitivity (48%) limits its usefulness as a screening test for chronic lead nephropathy.

Chronic renal failure with gout: a marker of chronic lead poisoning

EDTA (calcium disodium edetate) lead mobilization and x-ray fluorescence (XRF) finger bone lead tests were done in 42 patients with chronic renal failure and without persisting lead intoxication. Nineteen of 23 patients with gout and 8 of 19 without gout had positive EDTA lead mobilization tests. Those patients with gout excreted significantly more excess lead chelate than those without gout. In the gout group 17 patients denied any childhood or industrial exposure to lead. They had a greater number of positive tests and excreted significantly more excess lead chelate than 14 patients with neither gout nor lead exposure. These results confirm that gout in the presence of chronic renal failure is a useful marker of chronic lead poisoning. Of 27 patients with positive lead mobilization tests, only 13 had elevated XRF finger bone lead concentrations (sensitivity 48%). Three of 15 patients with negative lead mobilization tests had elevated XRF finger bone lead concentrations (specificity 80%). Although the XRF finger bone lead test is a convenient noninvasive addition to the diagnostic evaluation of patients with chronic renal failure and gout, its application is limited due to the lack of sensitivity of the method.

In vivo X-ray fluorescence estimation of bone lead concentrations in Queensland adults

A group of 200 Queensland adults without known health problems had in-vivo estimation of finger bone lead concentrations using X-ray fluorescence analysis (XRF). Forty of these subjects had elevated levels of bone lead of 25 ppm or more, consistent with exposure to the metal. Although the correlation between Queensland residence during childhood and raised bone lead levels was not significant, there were significant correlations between childhood residence in a painted wooden house and raised levels, and between occupational exposure and raised levels. Of the 40 subjects with elevated lead levels only two had neither a history of occupational exposure or childhood residence in a wooden house, whereas 11 of the 25 who had a history of both occupational and residential exposure were positive. The data are consistent with lead in housepaint, or absorbed during occupational exposure, being the two major sources of raised bone lead concentrations.

Liver cadmium concentrations in metal industry workers

In vivo neutron activation analysis of liver cadmium concentration was performed in 285 metal workers, 130 of whom had been exposed to cadmium in the workplace. Only two workers showed pathological levels in excess of 50 ppm. However, mean liver, urine and blood cadmium levels were significantly different as between the exposed and the unexposed workers. In vivo neutron activation analysis of liver cadmium concentration is easy to perform and can readily be used for industrial screening whenever a hazard is suspected.

Cerebellar calcification--ultrastructure and histochemistry

The histochemistry and ultrastructure of calcified cerebellar deposits described by Tonge et al. (1977) are reported. The deposits were located by electron microscopy in the walls of blood vessels outside the basement membrane and, in most lesions, consisted of short fibrillar material arranged in multiple lamellae. A number of nonlaminated small bodies were present also. The material coated the vessel walls discontinuously with major and minor protrusions into adjacent nervous tissue. Histochemical analysis detected the presence of sialopolysaccharides in the lesions in adults and in a case of plumbism in a child, with minor differences in the type of sialic acid. X-ray fluorescence analysis supported by histochemical data indicated that, initially, the calcium was bound to the sialic acid and that calcium phosphate appeared in the lesions at a later date. The authors conclude that the lesion is formed by elaboration of sialopolysaccharides at the site but the possibility was not excluded that the polysaccharide may have been derived from a transudate across the vessel wall.

Isolation of Neisseria meningitidis from the urethra, cervix, and anal canal: further observations

Neisseria meningitidis was recovered from the urethra of nine and from the anal canal of seven men, and from the cervix of two women. Twelve of the 16 men were admitted homosexuals. Seven men had no symptoms, while the remainder had mild to moderate symptoms. One woman was asymptomatic and the other was in hospital with acute salpingitis. Reports of previous isolations of meningococci from the urethra, cervix, or anal canal are reviewed. It is concluded that in men, these infections are usually mild and self-limited, but in women, meningococcal genital infections frequently proceed to severe disease.