Effects of arginine vasopressin on human anxiety and associations with sex, dose, and V1a-receptor genotype

RATIONALE

Arginine vasopressin (AVP) has dose- and sex-specific effects on social behavior, and variation in social responses is related to variation in the V1a receptor gene in animals. Whether such complexity also characterizes AVP effects on anxiety in humans, or whether V1a genotype is related to anxiety and/or AVP's ability to affect it, remains to be determined.

OBJECTIVE

To test if AVP has dose-dependent effects on anxiety in men and/or women and if a particular allele within the RS3 promoter region of the V1a receptor gene is associated with anxiety and/or AVP effects on anxiety.

METHOD

Men and women self-administered 20 IU or 40 IU intranasal arginine vasopressin (AVP) and placebo in a double-blind, within-subjects design, and State (SA) and Trait (TA) anxiety were measured 60 min later. PCR was used to identify allelic variation within the RS3 region of the V1a receptor gene.

RESULTS

AVP decreased SA in men across both doses, whereas only the lower dose had the same effect, across sexes, in individuals who carry at least one copy of a previously identified "risk" allele in the RS3 promoter of the V1a receptor gene. Additionally, after placebo, women who carried a copy of the allele displayed lower TA than women who did not, and AVP acutely increased TA scores in those women.

CONCLUSIONS

Exogenous AVP has modest sex- and dose-dependent effects on anxiety/affect in humans. Further, allelic variation in the V1a promoter appears associated with responsiveness to AVP's effects and, at least in women, to stable levels of anxiety/affect.

993. “I feel like they’re actually listening to me”: A Pilot Study of Hospital Discharge-Decision Making for Patients with Injection Drug Use-Associated Infections

Background

Conversation guides have the potential to transform care for patients hospitalized with injection drug use (IDU)-associated infections. This study’s objectives were to 1) pilot a structured conversation guide for hospital discharge decision making in patients with IDU-associated infections 2) investigate the guide’s feasibility and acceptability and 3) examine patient and provider experiences, patient outcomes, and lessons learned.

Methods

We developed a conversation guide and conducted semi-structured interviews with physicians and patients at a tertiary care center in Maine. We interviewed physicians after each piloted the guide with two patients. We interviewed patients less than one week after the conversation and again after 4-6 weeks. Two analysts indexed transcriptions and used the framework method to identify and organize relevant information. We conducted retrospective chart review to corroborate and contextualize qualitative data.

Results

Eight patients and four infectious disease physicians piloted the conversation guide. All patients (N=8) completed antimicrobial treatment and 88% were discharged on medication for opioid use disorder (Table 1). All providers and most patients stated that the conversation guide was important for incorporating patient preferences and antimicrobial treatment options. Patients appreciated more autonomy and their voices being included in their care. Providers felt the guide facilitated their understanding of patient values. Values and preferences between patients and providers were aligned. Participants identified the length of the guide, discussion of pain management, and addressing post-discharge needs such as housing as areas for improvement (Table 2).

Conclusion

The use of a conversation guide to inform hospital discharge decision making for patients with IDU-associated infections incorporates patient preferences and values into treatment decisions. While we identified areas for improvement, overall patients and providers believed that this novel conversation guide helped to improve patient care and autonomy.

Disclosures

Kinna Thakarar, DO, MPH, Maine Medical Center: Board Member|NIH: Grant/Research Support|University of New England: Board Member Monica K. Sikka, MD, F2G: Site research investigator Ellen Eaton, MD, MSPH, Gilead: Grant/Research Support.

Association of Patient Belief About Success of Antibiotics for Appendicitis and Outcomes: A Secondary Analysis of the CODA Randomized Clinical Trial

Importance

A patient's belief in the likely success of a treatment may influence outcomes, but this has been understudied in surgical trials.

Objective

To examine the association between patients' baseline beliefs about the likelihood of treatment success with outcomes of antibiotics for appendicitis in the Comparison of Outcomes of Antibiotic Drugs and Appendectomy (CODA) trial.

Design, Setting, and Participants

This was a secondary analysis of the CODA randomized clinical trial. Participants from 25 US medical centers were enrolled between May 3, 2016, and February 5, 2020. Included in the analysis were participants with appendicitis who were randomly assigned to receive antibiotics in the CODA trial. After informed consent but before randomization, participants who were assigned to receive antibiotics responded to a baseline survey including a question about how successful they believed antibiotics could be in treating their appendicitis.

Interventions

Participants were categorized based on baseline survey responses into 1 of 3 belief groups: unsuccessful/unsure, intermediate, and completely successful.

Main Outcomes and Measures

Three outcomes were assigned at 30 days: (1) appendectomy, (2) high decisional regret or dissatisfaction with treatment, and (3) persistent signs and symptoms (abdominal pain, tenderness, fever, or chills). Outcomes were compared across groups using adjusted risk differences (aRDs), with propensity score adjustment for sociodemographic and clinical factors.

Results

Of the 776 study participants who were assigned antibiotic treatment in CODA, a total of 425 (mean [SD] age, 38.5 [13.6] years; 277 male [65%]) completed the baseline belief survey before knowing their treatment assignment. Baseline beliefs were as follows: 22% of participants (92 of 415) had an unsuccessful/unsure response, 51% (212 of 415) had an intermediate response, and 27% (111 of 415) had a completely successful response. Compared with the unsuccessful/unsure group, those who believed antibiotics could be completely successful had a 13-percentage point lower risk of appendectomy (aRD, -13.49; 95% CI, -24.57 to -2.40). The aRD between those with intermediate vs unsuccessful/unsure beliefs was -5.68 (95% CI, -16.57 to 5.20). Compared with the unsuccessful/unsure group, those with intermediate beliefs had a lower risk of persistent signs and symptoms (aRD, -15.72; 95% CI, -29.71 to -1.72), with directionally similar results for the completely successful group (aRD, -15.14; 95% CI, -30.56 to 0.28).

Conclusions and Relevance

Positive patient beliefs about the likely success of antibiotics for appendicitis were associated with a lower risk of appendectomy and with resolution of signs and symptoms by 30 days. Pathways relating beliefs to outcomes and the potential modifiability of beliefs to improve outcomes merit further investigation.

Trial Registration

ClinicalTrials.gov Identifier: NCT02800785.

Health care professional perspectives on discharging hospitalized patients with injection drug use-associated infections

Background:

Patients with injection drug use (IDU)-associated infections traditionally experience prolonged hospitalizations, which often result in negative experiences and bad outcomes. Harm reduction approaches that value patient autonomy and shared decision-making regarding outpatient treatment options may improve outcomes. We sought to identify health care professionals (HCPs) perspectives on the barriers to offering four different options to hospitalized people who use drugs (PWUD): long-term hospitalization, oral antibiotics, long-acting antibiotics at an infusion center, and outpatient parenteral antibiotics.

Methods:

We recruited HCPs (n = 19) from a single tertiary care center in Portland, Maine. We interviewed HCPs involved with discharge decision-making and other HCPs involved in the specialized care of PWUD. Semi-structured interviews elicited lead HCP values, preferences, and concerns about presenting outpatient antimicrobial treatment options to PWUD, while support HCPs provided contextual information. We used the iterative categorization approach to code and thematically analyze transcripts.

Results:

HCPs were willing to present outpatient treatment options for patients with IDU-associated infections, yet several factors contributed to reluctance. First, insufficient resources, such as transportation, may make these options impractical. However, HCPs may be unaware of existing community resources or viable treatment options. They also may believe the hospital protects patients, and that discharging patients into the community exposes them to structural harms. Some HCPs are concerned that patients with substance use disorder will not make ‘good’ decisions regarding outpatient antimicrobial options. Finally, there is uncertainty about how responsibility for offering outpatient treatment is shared across changing care teams.

Conclusion:

HCPs perceive many barriers to offering outpatient care for people with IDU-associated infections, but with appropriate interventions to address their concerns, may be open to considering more options. This study provides important insights and contextual information that can help inform specific harm reduction interventions aimed at improving care of people with IDU-associated infections.

Injections and infections: understanding syringe service program utilization in a rural state

BACKGROUND

Increasing rates of injection drug use (IDU) associated-infections suggest significant syringe service program (SSP) underutilization. Our study objective was to assess practices of safe injection techniques and to determine predictors of SSP utilization in a rural state.

PATIENTS AND METHODS

This was a fifteen-month cross-sectional study of participants hospitalized with IDU-associated infections in Maine. Data were collected through Audio Computer-Assisted Self-Interview survey and medical record review. Descriptive analyses were performed to characterize demographics, health characteristics, and injection practices. The primary outcome was SSP utilization, and the main independent variable was self-reported distance to SSP. Logistic regression analyses were performed to identify factors associated SSP utilization, controlling for gender, homelessness, history of overdose, having a primary care physician and distance to SSP.

RESULTS

Of the 101 study participants, 65 participants (64%) reported past 3 month SSP utilization, though only 33% used SSPs frequently. Many participants (57%) lived more than 10 miles from an SSP. Participants who lived less than 10 miles of an SSP were more likely to use an SSP (adjusted odds ratio 5.4; 95% CI 1.9-15.7).

CONCLUSIONS

Our study highlights unsafe injection practices and lack of frequent SSP utilization among people admitted with IDU-associated infections in a rural state. Especially given increasing stimulant use, these results also highlight the need for SSP access. Particularly in rural areas where patients may live more than 10 miles from an SSP, expansion of harm reduction services, including mobile units, should be a priority.

Dose-Dependent and Lasting Influences of Intranasal Vasopressin on Face Processing in Men

Arginine vasopressin (AVP) and related peptides have diverse effects on social behaviors in vertebrates, sometimes promoting affiliative interactions and sometimes aggressive or antisocial responses. The type of influence, in at least some species, depends on social contexts, including the sex of the individuals in the interaction and/or on the levels of peptide within brain circuits that control the behaviors. To determine if AVP promotes different responses to same- and other-sex faces in men, and if those effects are dose dependent, we measured the effects of two doses of AVP on subjective ratings of male and female faces. We also tested if any influences persist beyond the time of drug delivery. When AVP was administered intranasally on an initial test day, 20 IU was associated with decreased social assessments relative to placebo and 40 IU, and some of the effects persisted beyond the initial drug delivery and appeared to generalize to novel faces on subsequent test days. In single men, those influences were most pronounced, but not exclusive, for male faces, whereas in coupled men they were primarily associated with responses to female faces. Similar influences were not observed if AVP was delivered after placebo on a second test day. In a preliminary analysis, the differences in social assessments observed between men who received 20 and 40 IU, which we suggest primarily reflect lowered social assessments induced by the lower dose, appeared most pronounced in subjects who carry what has been identified as a risk allele for the V1a receptor gene. Together, these results suggest that AVP's effects on face processing, and possibly other social responses, differ according to dose, depend on relationship status, and may be more prolonged than previously recognized.

Corrigendum: Dose-Dependent and Lasting Influences of Intranasal Vasopressin on Face Processing in Men

[This corrects the article on p. 220 in vol. 8, PMID: 29018407.].

Vein patch angioplasty with non-penetrating titanium clips. Comparison to standard suture technique

Our purpose was to compare the Vascular Closure Staples (VCS) clips to a standard suture technique for vein patch angioplasty in a porcine model. Six female pigs underwent vein patch angioplasty of the common iliac arteries with either VCS clips or continuous suturing. The reconstructed vessels were evaluated macroscopically, angiographically and histologically after two months by re-operation. There was a non significant trend towards shorter reconstruction (6.5 +/- 1.8 min. for clips vs. 8.5 +/- 1.7 min. for sutures, p = 0.15) and clamp times when clips were used (8.4 +/- 1.5 min. vs. 10.1 +/- 1.3 min., p = 0.15). At re-operation all vessels were found patent without significant histological differences regarding the intimal reaction. VCS clips are a reliable alternative to sutures for vein patch angioplasty.

Blood substitutes in surgery

BACKGROUND

Despite increasing safety of blood supplies, and blood conservation strategies, the need for blood transfusion is increasing. Due to storage characteristics, blood is not always available when it is needed.

AIMS

Review the necessity for an oxygen carrying blood substitute. Review the history of the compounds that may become blood substitutes, and briefly describe those in clinical trials.

MATERIAL AND METHODS

Review of literature in the area of blood substitutes.

RESULTS AND CONCLUSIONS

There is a need for oxygen carrying blood substitutes. Despite disappointments in recent clinical trials leading to withdraw of some compounds, there are several promising products nearing clinical approval.

Biliary giardiasis in a patient with human immunodeficiency virus

A 41-year-old man with human immunodeficiency virus (HIV) (CD4 count, 446/mm3) developed a protracted course of abdominal pain, weight loss, and increasing liver function tests after undergoing a metronidazole treatment regimen for Giardia enteritis. Three months later, endoscopic retrograde cholangiography (ERCP) showed dilated common and intrahepatic bile ducts and luminal irregularities of the common bile duct. Seven months after the onset of his acute diarrhea, a repeat ERCP with aspiration demonstrated many Giardia trophozoites and cysts in the bile and continued structural abnormalities consistent with cholangiopathy. A 10-day course of high-dose intravenous metronidazole did not resolve these signs or symptoms. A gallbladder ultrasound showed a thickened wall. Laparoscopic cholecystectomy led to resolution of abdominal pain and normalization of serum alkaline phosphatase over an 8-month period. Gallbladder histopathology revealed chronic cholecystitis, but no parasites were seen on hematoxylin and eosin staining or with Giardia antigen enzyme immunoassay testing of the gallbladder. The patient refused to undergo a follow-up ERCP, but a right upper quadrant ultrasound and computed tomography of the abdomen were normal.

Comparison of titanium vascular closure staples with suture repair of the thoracic aorta in swine

OBJECTIVE

Devices that reduce technical difficulty and anastigmatic time when repairing large vessels such as the thoracic aorta would be beneficial. The aim of this study was to determine if titanium vascular closure staples (3 mm) could be safely and quickly applied in the repair of large vessels such as the thoracic aorta.

DESIGN

Through a left thoracotomy in 10 female swine (110 to 130 lb), an interposition graft (14 to 16 mm textile) was placed into the aorta distal to the left subclavian artery. Animals were randomized at the time of repair to either running sutures (n = 5; 6-0 polypropylene) or vascular closure staples (n = 5; 3 mm). The anastomosis was evaluated after 2 months with aortograms, and the aorta was harvested to evaluate healing.

RESULTS

The clamp times (mean +/- SD) were 30.8 +/- 8.2 min for suture repair and 24.8 +/- 5.1 min for vascular closure staple repair (p = 0.2). Anastomosis times were 20. 0 +/- 6.2 min for the suture group and 16.4 +/- 6.4 min for the vascular closure staple group (p = 0.4). Arch aortograms at 2 months revealed no significant difference in luminal narrowing between the two groups. Gross and microscopic examination revealed no thrombosis, well-healed wounds with a continuous intimal layer, and no differences in intimal thickness or inflammation between the two groups.

CONCLUSION

Vascular closure staples were equivalent to sutures in terms of durability, graft patency, and wound healing at 2 months. Vascular closure staples may offer the trauma surgeon a quick and easy alternative when repairing large vessels such as the thoracic aorta.

E- and P-selectin expression depends on the resuscitation fluid used in hemorrhaged rats

BACKGROUND

E- and P-selectins are adhesion molecules that effect neutrophil-mediated reperfusion injury. Our hypothesis was that the expression of E- and P-selectins is dependent on the type of fluid used for resuscitation and that lactated Ringer's (LR) solution would result in an early upregulation of these molecules.

METHODS

Male Sprague-Dawley rats (n = 36) were subjected to a 27 ml/kg hemorrhage over 5 min followed by a 1-h shock period and 1-h of resuscitation. The animals were randomized into the following resuscitation groups: (1) sham; (2) hemorrhage, no resuscitation; (3) whole blood (27 ml/kg); (4) 3:1 lactated Ringer's (81 ml/kg); (5) sham hemorrhage, infusion of lactated Ringer's (81 ml/kg); (6) 7. 5% hypertonic saline (9.7 ml/kg). Immediately after resuscitation, the spleen and lung were harvested for measurement of E- and P-selectin mRNA expression with reverse transcriptase- polymerase chain reaction (RT-PCR), and protein expression with immunostaining.

RESULTS

LR resuscitation and LR infusion without prior hemorrhage significantly increased the E- and P-selectin mRNA in the lung and spleen. Immunostaining demonstrated that the adhesion molecule expression was mainly located in perivascular/peribronchial areas in the lung, and the marginal and trabecular areas in the spleen. Pulmonary edema and inflammatory cell infiltration were observed only in the animals that were hemorrhaged and resuscitated with LR. No resuscitation and resuscitation with whole blood caused no significant increase in selectin expression.

CONCLUSION

LR resuscitation and LR infusion without hemorrhage are associated with early increased expression of E- and P-selectin molecules in the lung and spleen.

Lactated ringer's solution and hetastarch but not plasma resuscitation after rat hemorrhagic shock is associated with immediate lung apoptosis by the up-regulation of the Bax protein

BACKGROUND

We previously demonstrated that the type of resuscitation fluid used in hemorrhagic shock affects apoptosis. Unlike crystalloid, whole blood seems to attenuate programmed cell death. The purpose of this study was to determine whether the acellular components of whole blood (plasma, albumin) attenuated apoptosis and to determine whether this process involved the Bax protein pathway.

METHODS

Rats were hemorrhaged 27.5 mL/kg, kept in hypovolemic shock for 75 minutes, then resuscitated over 1 hour (n = 44). Control animals underwent anesthesia only (sham, n = 7). Treatment animals were bled then randomly assigned to the following resuscitation groups: no resuscitation (n = 6), whole blood (n = 6), plasma (n = 6), 5% human albumin (n = 6), 6% hetastarch (n = 7), and lactated Ringer's solution (LR, n = 6). Hetastarch was used to control for any colloid effect. LR was used as positive control. Immediately after resuscitation, the lung was collected and evaluated for apoptosis by using two methods. TUNEL stain was used to determine general DNA damage, and Bax protein was used to specifically determine intrinsic pathway involvement.

RESULTS

LR and hetastarch treatment resulted in significantly increased apoptosis in the lung as determined by both TUNEL and Bax expression (p < 0.05). Plasma infusion resulted in significantly less apoptosis than LR and hetastarch resuscitation. Multiple cell types (epithelium, endothelium, smooth muscle, monocytes) underwent apoptosis in the lung as demonstrated by the TUNEL stain, whereas Bax expression was limited to cells residing in the perivascular and peribronchial spaces.

CONCLUSION

Apoptosis after volume resuscitation of hemorrhagic shock can be affected by the type of resuscitation fluid used. Manufactured fluids such as lactated Ringer's solution and 6% hetastarch resuscitation resulted in the highest degree of lung apoptosis. The plasma component of whole blood resulted in the least apoptosis. The process of apoptosis after hemorrhagic shock resuscitation involves the Bax protein.

Intraosseous infusion devices: a comparison for potential use in special operations

OBJECTIVE

To determine which intraosseous (IO) devices were easy to learn to use, easy to use once the skill was obtained, and appropriate for the Special Operations environment.

METHODS

Thirty-one Navy SEAL corpsmen, Air Force pararescuemen, Army Special Forces, and Ranger medics, in a prospective, randomly assigned, cross-over study, tested four commercially available, Food and Drug Administration-cleared IO devices. The systems included the injection models First Access for Shock and Trauma (FAST, Pyng Medical) and Bone Injection Gun (Wais Medical, Kress USA Corporation) and the hand-driven threaded-needle SurFast (Cook Critical Care) and straight-needle Jamshidi needle (Baxter) models. The Special Operations medical care providers received a lecture regarding IO use, viewed videotapes of the injection models, and practiced with demonstration units in the classroom. Each participant then entered the cadaver lab where all four of the IO devices were placed in randomly assigned order. A poststudy questionnaire was then completed. The FAST was placed in the sternum, whereas the other units were placed in either medial proximal or distal medial tibia. Each participant was assessed for time, number of attempts, and success. The presence of marrow, extravasation, quality of flow, and security of needle were evaluated in combination to help determine success.

RESULTS

All four devices were believed to be easy to learn as well as easy to place. FAST was successful in 29 of 30 insertions (94%) with a placement time of 114 +/- 36 (mean +/- SD) seconds. The Bone Injection Gun was similarly successful (29 of 31 insertions, 94%) with a mean placement time of 70 +/- 33 seconds. This time was statistically significantly faster (p < 0.05) than that with FAST, but not with the other devices. Thirty of 31 SurFast placements (97%) were successful, on average taking 88 +/- 33 seconds to place. The Jamshidi needle also had 30 of 31 successful placements (97%) at an average 90 +/- 59 seconds. No one device was rated by the participants as significantly better than the others; however, the Bone Injection Gun did have 65% of participants rate it as first or second (closest was Jamshidi needle at 52%).

CONCLUSION

These IO devices were easy to teach and learn as well as easy to use. Insertion times compared favorably with peripheral intravenous catheter placement in the face of hemorrhage. All four devices can be appropriately used in the Special Operations environment and are reasonable alternatives when intravenous access cannot be gained. Although no device was rated higher than the others, particular features are desirable (low weight/size, simplicity, reusability, secure, clean, well protected).

Induced hypothermia during emergency department thoracotomy: an animal model

BACKGROUND

Induced hypothermia is used clinically to prevent ischemic injury during elective procedures. We present an animal model of asanguinous hypothermic (10 degrees C) circulatory arrest, induced through a left anterior lateral thoracotomy after exsanguinating uncontrolled hemorrhage.

METHODS

Through a left anterior thoracotomy, 26 swine (45-70 kg) sustained a laceration of the descending thoracic aorta, producing exsanguinating uncontrolled hemorrhage. After 5 minutes of severe hypotension (systolic BP <20 mm Hg), a 22 French Foley catheter was directed cephalad through the enlarged aortic wound. A solution (containing 42.5 mmol/L K+ and precooled to 1 degrees C) was infused to arrest/preserve the heart and brain. A second 24 French Foley catheter was then directed caudally through the same wound. The right atrium was opened to drain the venous system. The animal was cooled with a cardiopulmonary bypass pump (>5L/min) through the Foley catheters. Once 10 degree C was reached, a cannula was placed to the aortic root and the aortic laceration repaired. The animal was maintained at 10 degree C for a total of 90 minutes. Before the rewarming process, the circulation was rinsed with a solution containing normal levels of electrolytes followed by infusion of whole blood. Rewarming was performed by maintaining a 10-degree gradient on the heat exchanger. The first 16 animals were used in nonsurvival experiments to develop the technique and to record dural temperatures and electroencephalogram tracings. The last 10 animals were used to determine long-term survival and neurologic outcome. Group I: seven animals were kept at < 10 degrees C with flows less than 2L/min. Group II: three animals underwent 20, 30, and 40 minutes of no flow once they were cooled to 10 degrees C. After 6 weeks of survival and neurologic examinations, the brains were fixed for histologic evaluations.

RESULTS

The average time to cool the head to 18 degrees C and 10 degrees C was 6 minutes and 12 minutes, respectively. The hematocrit fell below 2% by the end of the cooling period. A total of 7 of the 10 animals from the long-term study survived. Group I: five of seven animals survived. Four of the survivors had no appreciable neurologic deficits, were fully functional at 6 weeks, and had no evidence of histologic injury. One of the five survivors in this group had moderate neurologic disability. Of the two animals that died, one died from air embolism from the i.v. line. The second death was in an animal for which maximal cooling to 2.7 degrees C was attempted. Group II: The first two animals that had "no flow" for 20 and 30 minutes were fully functional and had normal neurologic examinations. However, the second animal was found to have brain injury on histologic examination. The last animal in this group died of accidental extubation during recovery.

CONCLUSION

Induction of hypothermic arrest through the chest after exsanguination is possible. The further development of this technique may provide an extended state of "suspended animation" to allow for repairs of hemorrhaging injuries in trauma patients who require emergency department thoracotomy.

Sutureless vascular reconstruction with titanium clips

Attempts to find alternatives to sutured vascular reconstruction techniques has continued for decades and include various forms of rings, tubes, endoluminal stents as well as gluing or welding techniques of large vessel anastomoses. One recently introduced technique uses nonpenetrating titanium clips for everted vessel approximation and closure. Experimental work on their use in various types of large vessel repairs and reconstructions has shown that the clips are easily applied with a short learning curve, create good conditions for vessel wall healing without causing excessive inflammation or fibrosis, and are considerably faster to apply when compared to standard suture techniques. Although there are some clinical reports of defective clipped closures causing postoperative bleeding complications, they are rare and most probably related to technical errors in applying the clips. The main disadvantages of the clips include the limited experience of their applicability in atherosclerotic vessels, lack of long term follow-up and cost. Potentially, the clips could be useful in the repair of multiple vascular injuries, in vessel repair or ligation performed in confined spaces, and in vascular procedures requiring the shortest possible cross-clamping time. Future applications could include endoscopic procedures as well as the use of a one-shot device which simultaneously applies up to a dozen clips to symmetrically everted and approximated vessel edges.

Arterial repair with synthetic patch by using titanium clips

BACKGROUND

Vascular closure staple (VCS) clips made of titanium were originally developed for microvascular anastomoses. There is limited experience with their applicability to vascular reconstruction in larger vessels. This study compares VCS clips to standard sutures in arterial repair using a synthetic patch.

METHODS

In an experimental study with pigs, two sequential 10-mm abdominal aortotomies were allocated randomly to synthetic patch (polytetrafluoroethylene) repair with VCS clips or continuous 6-0 polypropylene sutures. Angiographic, macroscopic, and microscopic results were assessed after 2 months.

RESULTS

There were no significant differences in the patency rate, vessel diameter at the repair site, or healing indices. The mean (SD) clamp time was 8.7 (3.0) minutes for clip repair and 14.3 (7.4) minutes for suture repair (p = 0.04), and the times required for the vessel reconstruction were 5.3 (1.3) and 9.3 (3.0) minutes, respectively (p = 0.009).

CONCLUSION

Patched arterial repair with VCS clips is faster than sutured reconstruction with comparable results after 2 months of follow up.

Human neutrophil activation and increased adhesion by various resuscitation fluids

OBJECTIVE

To determine whether activated neutrophils play a major role in secondary tissue injury after resuscitation in trauma. We hypothesized that human neutrophil activation and adhesion vary, depending on the type and amount of resuscitation fluid used.

SETTING

University-based research facility.

SUBJECTS

Ten healthy adult volunteers.

DESIGN

Whole blood from volunteers was serially diluted in polypropylene tubes with various resuscitation fluids. Fluids tested were phosphate-buffered saline, normal saline, lactated Ringer's solution, dextran, hespan, 5% human albumin, 25% human albumin, 3.5% hypertonic saline, and 7.5% hypertonic saline. Neutrophil activation (intracellular oxidative burst activity with dichlorofluorescin diacetate staining) and adhesion (integrin cell surface expression of CD18) were measured with flow cytometry (fluorescence-activated cell sorting). Blood was diluted with hypertonic saline by controlling for sodium content equal to normal saline. dose-related increase in neutrophil oxidative burst activity as the result of dilution followed with crystalloid fluids and artificial colloids (dextran and hespan). The increase was 12-18 x baseline at the 75% dilution. The increase with 5% human albumin was only 2.2 x baseline, and 25% albumin did not demonstrate any increased intracellular activity. A similar significant increase in the neutrophil adhesion expression (CD18) occurred with artificial colloids (p<.05) and, to a lesser extent, with crystalloids, but not with albumin. Hypertonic saline caused a decrease in CD18 cell surface expression.

CONCLUSIONS

This study suggests that the neutrophil activation and adhesion may vary, depending on the type of resuscitative fluid used. All artificial resuscitative fluids may not be similar or innocuous, as demonstrated by the dose-related increase in neutrophil activation and adhesion.

Cyclopentyladenosine improves cell proliferation, wound healing, and hair growth

BACKGROUND

N(6)-Cyclopentyladenosine (CPA), a structural analog of adenosine, is a vasodilator with extensive pharmacological effects. However, little is known about the effect of CPA on wound healing and hair growth.

METHODS

Cellular responses to CPA were measured in vitro by tetrazolium dye reduction and in vivo by bromodeoxyuridine (BrdU) uptake. The effect of CPA on healing of incisional and excisional wounds on the dorsum of diabetic (db/db, n = 94) and nondiabetic (db/+, n = 20) mice and hair growth along the wound margin was evaluated with wound breaking strength, wound closure rate, and quantitative histology.

RESULTS

CPA stimulated proliferation of BALB/3T3 fibroblasts and human dermal microvascular endothelial cells in both quiescent and nonquiescent phases. Wounds treated with CPA at 10 microM showed a significant increase in the number of BrdU-labeled cells, including keratinocytes, fibroblasts, endothelial cells, and cells in sebaceous glands and the outer root sheath of hair follicles, compared with controls (P < 0.05). CPA application (5.1 microg/daily for 12 days) significantly increased the breaking strength of incisional wounds at day 24 postwound (P < 0.05). Excisional wound closure rate in the CPA-treated group (3.4 microg/daily for 15 days) was accelerated starting at day 10 postwound compared with controls (P < 0.01). Tissue sections from CPA-treated wounds showed a sevenfold increase in hair follicle number, compared with controls (P < 0.01). Enhanced hair growth along the wound margin was revealed in CPA-treated groups.

CONCLUSION

CPA stimulated proliferation of many cell types in vivo and in vitro and enhanced wound healing and hair growth. Therefore, CPA could be an interesting candidate for clinical application.

Telepresence surgery system enhances medical student surgery training

The telepresence surgery system (TeSS) permits the surgeon to operate on a patient across distances. This is achieved through real-time 3D video vision, stereo audio, and remote instrument control with haptic feedback. Telepresence surgery has been proposed to be useful in providing specialist operative consultation to remote areas. Remotely mentoring medical students with no surgical experience through complex procedures provides an even greater challenge. Third-year medical students with no prior operative experience were mentored exclusively through use of TeSS during a standard surgical skills lab. This two-day laboratory includes abdominal procedures and thoracic procedures. The medical students were alone in the operating room and the teaching surgeon was in an entirely separate room. Anatomy, surgical principles, and adjunct techniques were taught to the students. The students felt the experience was better than standard because of the enhanced learning secondary to the required verbal accuracy in describing the procedures. In addition, they felt they had better visibility since the instructor was not standing in the way. The telepresence surgery system can be successfully used to remotely mentor and enhance introductory surgical training for inexperienced medical students.

Early up-regulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression in rats with hemorrhagic shock and resuscitation

This study evaluated the effect of resuscitation fluids on intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Sprague-Dawley rats (n = 36) were subjected to a 27 mL/kg hemorrhage over 5 min followed by a 1 h shock and 1 h resuscitation. Animals groups included: 1) cannulation only (Sham); 2) hemorrhage only (NR); 3) resuscitation with 1:1 shed blood (Blood); 4) resuscitation with 3:1 lactated Ringer's (81 mL/kg, 3LR+); 5) no hemorrhage but infusion with 3:1 lactated Ringer's (3LR); and 6) resuscitation with .36:1 hypertonic saline (7.5%, 9.7 mL/kg, HTS). At the end of resuscitation, the spleen and lung were harvested for detection of adhesion molecule mRNA and protein by RT-PCR and immunostaining. ICAM-1 and VCAM-1 expression exhibited the following pattern: 3LR+ > HTS approximate to 3LR > Blood approximate to NR approximate to Sham. VCAM-1 mRNA in the lung of the 3LR+ group was 2 or more times more than the groups of Sham, NR, Blood, and 3LR (p < .05). ICAM-1 and VCAM-1 mRNA in the spleen was significantly increased in the 3LR+ group compared with the groups of Sham, NR, and Blood (p < .05). Animals in the 3LR+ group showed enhanced staining for ICAM-1 in the pulmonary microvessels and in the marginal and trabecular areas of the spleen. Pulmonary edema and inflammatory cell infiltration were observed only in the 3LR+ group. In summary, resuscitation with LR following hemorrhagic shock induced immediate up-regulation of ICAM-1 and VCAM-1, which was associated with tissue injury. Thus, the type of resuscitation fluid used affected resuscitation injury.

Resuscitation with lactated Ringer's solution in rats with hemorrhagic shock induces immediate apoptosis

BACKGROUND

We hypothesize that different resuscitative fluids may immediately affect the degree of apoptosis after hemorrhagic shock.

METHODS

Rats (n = 35) were hemorrhaged 27 mL/kg over 5 minutes followed by 1 hour of shock, then resuscitation over 1 hour. The six treatment groups were sham hemorrhage, sham resuscitation, whole blood resuscitation, lactated Ringer's solution (LR) resuscitation with three times the volume bled, sham hemorrhage with LR infusion, and 7.5% hypertonic saline resuscitation (9.7 mL/kg). Liver and small intestine were harvested immediately after resuscitation. Apoptosis was evaluated by using in situ cell death detection method.

RESULTS

Resuscitation with LR resulted in a significant increase in small intestinal and liver apoptosis. Animals that received LR infusion without hemorrhage had an increased level of apoptosis in the intestine. Apoptosis in the intestine was observed in both the mucosa and muscularis externa. There was no increase in apoptosis in either organ in the animals resuscitated with sham resuscitation, whole blood, and hypertonic saline compared with the sham hemorrhage group.

CONCLUSION

Resuscitation with LR solution after hemorrhagic shock increased immediate cell death by apoptosis in both the small intestine and liver. There was no significant increase in apoptosis in the animals resuscitated with hypertonic saline, whole blood, or in unresuscitated animals. Thus, the type of resuscitation fluid used may affect the apoptotic cellular response to shock.

Controlled resuscitation for uncontrolled hemorrhagic shock

OBJECTIVE

To test the hypothesis that controlled resuscitation can lead to improved survival in otherwise fatal uncontrolled hemorrhage.

METHODS

Uncontrolled hemorrhage was induced in 86 rats with a 25-gauge needle puncture to the infrarenal aorta. Resuscitation 5 minutes after injury was continued for 2 hours with lactated Ringer's solution (LR), 7.3% hypertonic saline in 6% hetastarch (HH), or no fluid (NF). Fluids infused at 2 mL x kg(-1) x min(-1) were turned on or off to maintain a mean arterial pressure (MAP) of 40, 80, or 100 mm Hg in six groups: NF, LR 40, LR 80, LR 100, HH 40, and HH 80. Blood loss was measured before and after 1 hour of resuscitation.

RESULTS

Survival was improved with fluids. Preresuscitation blood loss was similar in all groups. NF rats did not survive 4 hours. After 72 hours, LR 80 rats (80%) and HH 40 rats (67%) showed improved survival over NF rats (0%) (p < 0.05). Rebleeding increased with MAP. Attempts to restore normal MAP (LR 100) led to increased blood loss and mortality.

CONCLUSION

Controlled resuscitation leads to increased survival compared with no fluids or standard resuscitation. Fluid type affects results. Controlled fluid use should be considered when surgical care is not readily available.

Rapid arterial anastomosis with titanium clips

BACKGROUND

The obvious advantages of rapid arterial anastomoses have prompted the continuing search for more rapid anastomotic techniques to complement the standard sutured anastomosis. Nonpenetrating, arcuate-legged titanium vascular closure staple (VCS) clips were initially developed for microvascular anastomoses. The purpose of this study was to compare VCS clips with sutured arterial end-to-end anastomosis in larger vessels.

METHODS

In 6 pigs, transacted iliac arteries were reanastomosed with VCS clips on one side and continuous 6-0 polypropylene suture on the other.

RESULTS

The reconstruction time was 8.4+/-5.2 minutes for clip closure and 12.0+/-6.6 minutes for suture closure (P = 0.033). All vessels were patent half an hour after completing the anastomoses with no signs of early thrombosis.

CONCLUSIONS

Arterial end-to-end anastomosis can be performed more rapidly with VCS clips than continuous sutures, and are potentially useful in situations where the clamp time of the vessel is critical.

Lactated Ringer's solution resuscitation causes neutrophil activation after hemorrhagic shock

PURPOSE

To determine the degree of neutrophil activation caused by hemorrhagic shock and resuscitation.

METHODS

Awake swine underwent 15-minute 40% blood volume hemorrhage, and a 1-hour shock period, followed by resuscitation with: group I, lactated Ringer's solution (LR); group II, shed blood; and group III, 7.5% hypertonic saline (HTS). Group IV underwent sham hemorrhage and LR infusion. Neutrophil activation was measured in whole blood using flow cytometry to detect intracellular superoxide burst activity.

RESULTS

Neutrophil activation increased significantly immediately after hemorrhage, but it was greatest after resuscitation with LR (group I, 273 vs. 102%; p < 0.05). Animals that received shed blood (group II) and HTS (group III) had neutrophil activity return to baseline state after resuscitation. Group IV animals had an increase in neutrophil activation (259 vs. 129%; p < 0.05).

CONCLUSION

Neutrophil activation occurring after LR resuscitation and LR infusion without hemorrhage, but not after resuscitation with shed blood or HTS, suggests that the neutrophil activation may be caused by LR and not by reperfusion.

Cellular responses to surgical trauma, hemorrhage, and resuscitation with diaspirin cross-linked hemoglobin in rats

BACKGROUND

Resuscitation with acellular oxygen carrier solutions offers the potential advantage of improved oxygen delivery compared with crystalloid solutions, but the detailed consequences of improved resuscitation have not been fully evaluated. This study evaluated local and systemic cellular effects of trauma, hemorrhage, and resuscitation in a model of hemorrhage and surgical trauma.

METHODS

Rats with a 10 cm full-thickness incisional wound and a 15 mL/kg hemorrhage were either not resuscitated or resuscitated with blood or diaspirin cross-linked hemoglobin (DCLHb). Cellular proliferative responses were evaluated at 1.5, 6, 24, and 48 hours after wounding by labeling in vivo with 5-bromo-2'-deoxyuridine. Plasma levels of interleukin-6, tumor necrosis factor-alpha, and interferon-gamma were measured by bioassay or enzyme-linked immunosorbent assay (ELISA). Bacterial translocation was measured by culturing liver homogenates.

RESULTS

Trauma inhibited keratinocyte and hepatocyte proliferation at 1.5 and 6 hours, and stimulated subsequent proliferation of keratinocytes and liver nonparenchymal cells. DCLHb stimulated wound keratinocyte proliferation, attenuated the inhibition of hepatocyte proliferation, eliminated bacterial translocation to the liver, protected the intestine from ischemic damage, and induced a rapid increase of interleukin-6 during the early phase of injury.

CONCLUSIONS

Surgical trauma alone, or in combination with hemorrhage, modulated cell proliferation both in the wound and in the remote organs of intestine and liver. DCLHb enhanced wound healing and cell proliferation as well as, or better than, freshly drawn blood, which may be beneficial for trauma care.

Fluid resuscitation in a model of uncontrolled hemorrhage: too much too early, or too little too late?

Early fluid resuscitation in hypotensive trauma patients is controversial due to the risk of increasing blood loss and mortality. We determined the effects of infusion rate and time of resuscitation on blood loss and mortality and compared the outcome to nonresuscitated animals in severe, uncontrolled hemorrhagic shock in a rat model. In anesthetized rats, piercing of the infrarenal aorta with a 25-G needle caused a fall of mean arterial pressure to <20 mm Hg and blood loss of about 20 ml/kg in 90% of the animals. Animals were assigned to the following treatment groups (n = 6): 60 ml/kg of lactated Ringer's solution (LR) infused at a rate of 1.5 ml/min and given at 2.5 min (Group I), 5 min (Group II), or 10 min (Group III) postinjury, or LR infused at a rate of 3.0 ml/min and given at 5 min (Group IV) or 10 min (Group V) postinjury. Another group (n = 9) was not resuscitated. The animals were followed for 3 hr. Total blood loss in Group I (30.5 +/- 2.6 ml/kg) was significantly (P < 0.05) higher when compared to nonresuscitated animals (22.1 +/- 0.8 ml/ kg) or Group III (22.7 +/- 1.0 ml/kg), and also significantly higher in Group IV (35.8 +/- 4.1 ml/kg) when compared to nonresuscitated animals or Group V (23.0 +/- 1.2 ml/kg). The mortality rate was 7/9 in nonresuscitated animals and 5/6 in Group IV, both were significantly higher than in Groups II, III, and V (0 or 1/6) and markedly higher than in Group I (2/6).

CONCLUSIONS

In this model of uncontrolled hemorrhage, initially uncorrected severe shock resulted in a high mortality rate. The risk of increased blood loss and mortality associated with early fluid resuscitation could be diminished by avoiding too fast of infusion rates early after the injury.

Early resuscitation with low-volume PolyDCLHb is effective in the treatment of shock induced by penetrating vascular injury

OBJECTIVE

To study the efficacy of an oxygen-carrying solution in early resuscitation of hemorrhagic shock induced by penetrating vascular injury.

DESIGN

Experimental study with anesthetized rats.

MATERIALS AND METHODS

Severe hemorrhagic shock was induced by a 25-gauge needle puncture to the infrarenal aorta. Forty animals were resuscitated 10 minutes after injury with either lactated Ringer's solution (LR; 60 mL/kg), 7.5% hypertonic saline (HTS; 5 mL/kg), or modified diaspirin cross-linked hemoglobin (PolyDCLHb; 5 or 20 mL/kg) or were not resuscitated (NR) and followed for 6 hours.

RESULTS

Total blood loss was similar in all treatment groups. Mean arterial pressure was restored to baseline values, base deficit was corrected to base excess, and venous oxygen saturation improved with PolyDCLHb and more slowly with LR but persisted below baseline values with HTS and NR. The 6-hour mortality rates were zero of eight (low-dose PolyDCLHb), three of eight (high-dose PolyDCLHb), two of eight (LR), six of eight (HTS), and six of eight (NR).

CONCLUSION

Early resuscitation with low-volume hemoglobin is effective in restoring tissue perfusion and improving survival in uncontrolled hemorrhagic shock.