Biomedical subjects

Daniel J Scott

Publications and source records attributed to Daniel J Scott.

At least 19 recordsLinked to original sources

PubMed2006

Construct and face validity and task workload for laparoscopic camera navigation: virtual reality versus videotrainer systems at the SAGES Learning Center.

BACKGROUND: Laparoscopic camera navigation (LCN) training on simulators has demonstrated transferability to actual operations, but no comparative data exist. The objective of this study was to compare the construct and face validity, as well as workload, of two previously validated virtual reality (VR) and videotrainer (VT) systems. METHODS: Attendees (n = 90) of the SAGES 2005 Learning Center performed two repetitions on both VR (EndoTower) and VT (Tulane Trainer) LCN systems using 30 degrees laparoscopes and completed a questionnaire regarding demographics, simulator characteristics, and task workload. Construct validity was determined by comparing the performance scores of subjects with various levels of experience according to five parameters and face validity according to eight. The validated NASA-TLX questionnaire that rates the mental, physical, and temporal demand of a task as well as the performance, effort, and frustration of the subject was used for workload measurement. RESULTS: Construct validity was demonstrated for both simulators according to the number of basic laparoscopic cases (p = 0.005), number of advanced cases (p < 0.001), and frequency of angled scope use (p < 0.001), and only for VT according to training level (p < 0.001) and fellowship training (p = 0.008). Face validity ratings on a 1-20 scale averaged 15.4 +/- 3 for VR vs. 16 +/- 2.6 for VT (p = 0.04). Ninety-six percent of participants rated both simulators as valid educational tools. The NASA-TLX overall workload score was 69.5 +/- 24 for VR vs. 68.8 +/- 20.5 for VT (p = 0.31). CONCLUSIONS: This is the largest study to date that compares two validated LCN simulators. While subtle differences exist, both VR and VT simulators demonstrated excellent construct validity, good face validity, and acceptable workload parameters. These systems thus represent useful training devices and should be widely used to improve surgical performance.

Adult↗

PubMed2006

Characterization of novel splice variants of LGR7 and LGR8 reveals that receptor signaling is mediated by their unique low density lipoprotein class A modules.

The relaxin and insulin-like peptide 3 receptors, LGR7 and LGR8, respectively, are unique members of the leucine-rich repeat-containing G-protein-coupled receptor (LGR) family, because they possess an N-terminal motif with homology to the low density lipoprotein class A (LDLa) modules. By characterizing several LGR7 and LGR8 splice variants, we have revealed that the LDLa module directs ligand-activated cAMP signaling. The LGR8-short variant encodes an LGR8 receptor lacking the LDLa module, whereas LGR7-truncate, LGR7-truncate-2, and LGR7-truncate-3 all encode truncated secreted proteins retaining the LGR7 LDLa module. LGR8-short and an engineered LGR7 variant missing its LDLa module, LGR7-short, bound to their respective ligands with high affinity but lost their ability to signal via stimulation of intracellular cAMP accumulation. Conversely, secreted LGR7-truncate protein with the LDLa module was able to block relaxin-induced LGR7 cAMP signaling and did so without compromising the ability of LGR7 to bind to relaxin or be expressed on the cell membrane. Although the LDLa module of LGR7 was N-glycosylated at position Asn-14, an LGR7 N14Q mutant retained relaxin binding affinity and cAMP signaling, implying that glycosylation is not essential for optimal LDLa function. Using real-time PCR, the expression of mouse LGR7-truncate was detected to be high in, and specific to, the uterus of pregnant mice. The differential expression and evolutionary conservation of LGR7-truncate further suggests that it may also play an important role in vivo. This study highlights the essential role of the LDLa module in LGR7 and LGR8 function and introduces a novel model of GPCR regulation.

Animals↗

PubMed2006

Solution structure and characterization of the LGR8 receptor binding surface of insulin-like peptide 3.

Insulin-like peptide 3 (INSL3), a member of the relaxin peptide family, is produced in testicular Leydig cells and ovarian thecal cells. Gene knock-out experiments have identified a key biological role in initiating testes descent during fetal development. Additionally, INSL3 has an important function in mediating male and female germ cell function. These actions are elicited via its recently identified receptor, LGR8, a member of the leucine-rich repeat-containing G-protein-coupled receptor family. To identify the structural features that are responsible for the interaction of INSL3 with its receptor, its solution structure was determined by NMR spectroscopy together with in vitro assays of a series of B-chain alanine-substituted analogs. Synthetic human INSL3 was found to adopt a characteristic relaxin/insulin-like fold in solution but is a highly dynamic molecule. The four termini of this two-chain peptide are disordered, and additional conformational exchange is evident in the molecular core. Alanine-substituted analogs were used to identify the key residues of INSL3 that are responsible for the interaction with the ectodomain of LGR8. These include Arg(B16) and Val(B19), with His(B12) and Arg(B20) playing a secondary role, as evident from the synergistic effect on the activity in double and triple mutants involving these residues. Together, these amino acids combine with the previously identified critical residue, Trp(B27), to form the receptor binding surface. The current results provide clear direction for the design of novel specific agonists and antagonists of this receptor.

Amino Acid Sequence↗

PubMed2006

Laparoscopic skills laboratories: current assessment and a call for resident training standards.

BACKGROUND: Numerous protocols for laparoscopic skills training using simulator-based laboratories have proven effective. However, little is known about the availability and uniformity of such facilities. The purpose of this study was to evaluate the prevalence, utilization, and costs of skills laboratories currently in use. METHODS: A survey was mailed to 253 general surgery program directors to determine the perceived value, prevalence, equipment, types of training, supervision, and costs of the labs. RESULTS: One hundred sixty-two (64%) programs completed the survey. Eighty-eight percent of responders consider skills labs effective in improving operating room performance; however, only 55% have skills labs. Of 89 programs with skills labs, 99% have videotrainer equipment (mean 3.8 trainers per lab, range 1 to 15); 46% have virtual reality trainer equipment (mean 1.7 trainers per lab, range 1 to 7). Eighty-two percent of programs teach basic skills using a variety of tasks (Rosser/Southwestern stations, MIST-VR, MISTELS, department-created); 96% teach suturing (intracorporeal, extracorporeal, suture devices). On average, residents train 0.8 hours per week (range 0 to 6). Training is mandatory in 55% and supervised in 73% of the programs. The mean development cost was 133,000 dollars (range 300 dollars to 1,000,000 dollars). CONCLUSIONS: While a large majority of program directors consider skills labs important, 45% of programs have no such facilities. Moreover, significant variability of equipment and training practices exist in currently available labs. Strategies are needed for more widespread implementation of skills labs, and standards should be developed to facilitate uniform adoption of validated curricula that reliably maximize training efficiency and educational benefit.

Clinical Competence↗

PubMed2006

Intensive continuing medical education course training on simulators results in proficiency for laparoscopic suturing.

BACKGROUND: The purpose of this study was to determine the feasibility and effectiveness of implementing a validated suturing curriculum as a free-standing continuing medical education (CME) course. METHODS: Eighteen participants (9 practicing surgeons, 9 surgery residents) attended a 4-hour laparoscopic suturing CME course. After viewing an instructional videotape all participants had their baseline performance measured on a fundamentals of laparoscopic surgery-type videotrainer suture model. Participants then practiced on the model with active instruction from 6 proctors until a previously reported proficiency level was achieved or until the course ended. Performance was scored objectively based on time and errors. Precourse and postcourse questionnaires were collected. RESULTS: Participants trained for 2.6 +/- .8 hours and performed 37 +/- 11 repetitions. Although no participant was proficient at baseline, 72% achieved the proficiency level by the end of the course. Participants showed 44% improvement in objective scores and 34% improvement according to subjective self-rating. CONCLUSIONS: Although 4 hours may be insufficient for some trainees, an intensive half-day CME course is feasible and effective in significantly improving performance and allowing the majority of participants to achieve proficiency.

Adult↗

PubMed2006

Proficiency maintenance: impact of ongoing simulator training on laparoscopic skill retention.

BACKGROUND: Proficiency-based training in laparoscopic suturing and knot tying translates to the operating room, but little is known about the durability of acquired skill. The purpose of this study was to determine the effect of maintenance training on skill retention after demonstration of proficiency. STUDY DESIGN: Medical students (n=18) with no previous laparoscopic or simulator experience were enrolled in an IRB-approved randomized controlled trial. All subjects trained to proficiency (score of 512, based on time and errors) on a previously validated suturing model (Fundamentals of Laparoscopic Surgery videotrainer). Subjects were then randomized to a control group, which received no additional training, and an ongoing training group, which trained again to proficiency at 1 and 3 months (immediately after testing). Simulator testing was repeated at 2 weeks, 1 month, 3 months, and 6 months after initial training. No subject had interval operative experience. RESULTS: Both groups demonstrated excellent skill retention during followup; performance scores, reported as means+/-SD, were 488+/-57 versus 482+/-55 at 2 weeks (p=ns), 483+/-81 versus 491+/-64 at 1 month (p=ns), 467+/-75 versus 470+/-67 at 3 months (p=ns), and 462+/-62 versus 492+/-43 at 6 months (p=0.02) for the control versus ongoing training groups, respectively. At 6 months, the ongoing training group showed better skill retention (95% versus 90%; p=0.02) and a trend for achieving the proficiency level (33% versus 18%; p=0.2) more often than the control group. CONCLUSIONS: Although proficiency-based training results in excellent skill retention, ongoing training substantially enhances performance and minimizes skill loss. Curricula should incorporate training that fosters maintenance of proficiency.

Adult↗

PubMed2006

Psychomotor testing predicts rate of skill acquisition for proficiency-based laparoscopic skills training.

BACKGROUND: Laparoscopic simulator training translates into improved operative performance. Proficiency-based curricula maximize efficiency by tailoring training to meet the needs of each individual; however, because rates of skill acquisition vary widely, such curricula may be difficult to implement. We hypothesized that psychomotor testing would predict baseline performance and training duration in a proficiency-based laparoscopic simulator curriculum. METHODS: Residents (R1, n = 20) were enrolled in an IRB-approved prospective study at the beginning of the academic year. All completed the following: a background information survey, a battery of 12 innate ability measures (5 motor, and 7 visual-spatial), and baseline testing on 3 validated simulators (5 videotrainer [VT] tasks, 12 virtual reality [minimally invasive surgical trainer-virtual reality, MIST-VR] tasks, and 2 laparoscopic camera navigation [LCN] tasks). Participants trained to proficiency, and training duration and number of repetitions were recorded. Baseline test scores were correlated to skill acquisition rate. Cutoff scores for each predictive test were calculated based on a receiver operator curve, and their sensitivity and specificity were determined in identifying slow learners. RESULTS: Only the Cards Rotation test correlated with baseline simulator ability on VT and LCN. Curriculum implementation required 347 man-hours (6-person team) and 795,000 dollars of capital equipment. With an attendance rate of 75%, 19 of 20 residents (95%) completed the curriculum by the end of the academic year. To complete training, a median of 12 hours (range, 5.5-21), and 325 repetitions (range, 171-782) were required. Simulator score improvement was 50%. Training duration and repetitions correlated with prior video game and billiard exposure, grooved pegboard, finger tap, map planning, Rey Figure Immediate Recall score, and baseline performance on VT and LCN. The map planning cutoff score proved most specific in identifying slow learners. CONCLUSIONS: Proficiency-based laparoscopic simulator training provides improvement in performance and can be effectively implemented as a routine part of resident education, but may require significant resources. Although psychomotor testing may be of limited value in the prediction of baseline laparoscopic performance, its importance may lie in the prediction of the rapidity of skill acquisition. These tests may be useful in optimizing curricular design by allowing the tailoring of training to individual needs.

Adult↗

PubMed2005

Developing and testing competency levels for laparoscopic skills training.

HYPOTHESIS: Expert levels can be developed for use as training end points for a basic video-trainer skills curriculum, and the levels developed will be suitable for training. DESIGN: Fifty subjects with minimal prior simulator exposure were enrolled using an institutional review board-approved protocol. As a measure of baseline performance, medical students (n = 11) and surgery residents (n = 39) completed 3 trials on each of 5 validated video-trainer tasks. Four board-certified surgeons established as laparoscopic experts (with more than 250 basic and more than 50 advanced cases) performed 11 trials on each of the 5 tasks. The mean score was determined and outliers (>2 SDs) were trimmed; the trimmed mean was used as the competency level. Baseline performance of each subject was compared with the competency level for each task. SETTING: All research was performed in a laparoscopic skills training and simulation laboratory. PARTICIPANTS: Medical students, surgical residents, and board-certified surgeons. MAIN OUTCOME MEASURES: Expert scores based on completion time and the number of subjects achieving these scores at baseline testing. RESULTS: For all tasks combined, the competency level was reached by 6% of subjects by the third trial; 73% of these subjects were chief residents, and none were medical students. CONCLUSIONS: These data suggest that the competency level is suitably challenging for novices but is achievable for subjects with more experience. Implementation of this performance criterion may allow trainees to reliably achieve maximal benefit while minimizing unnecessary training.

Clinical Competence↗

PubMed2005

Robotic Laparoscopic Fundoplication.

Gastroesophageal reflux disease is a very common disorder, and both medical and surgical treatments have shown outstanding results. Whereas proton pump inhibitors are the mainstay of treatment, laparoscopic fundoplication has become a very attractive alternative due to its efficacy and low morbidity. There are defined patient categories that may benefit more from laparoscopy than medical therapy, but a conclusive comparison between the two is lacking. Robotic laparoscopic fundoplication can be performed safely without increased morbidity. Potential advantages include enhanced precision, improved dexterity, and remote telesurgical applications. Disadvantages include increased cost and prolonged operative times. Further studies and more long-term outcome data are needed to fully evaluate the procedure. Robotic surgery is currently in its infancy and not cost effective but has a very promising future. With further development of automatization and miniaturization features, robotic surgery may prove more efficient than conventional laparoscopy.

Journal Article↗

PubMed2005

Simulator training for laparoscopic suturing using performance goals translates to the operating room.

BACKGROUND: The purpose of this study was to develop a performance-based laparoscopic suturing curriculum using simulators and to test the effectiveness (transferability) of the curriculum. STUDY DESIGN: Surgical residents (PGY1 to PGY5, n = 17) proficient in basic skills, but with minimal laparoscopic suturing experience, were enrolled in an IRB-approved, randomized controlled protocol. Subjects viewed an instructional video and were pretested on a live porcine laparoscopic Nissen fundoplication model by placing three gastrogastric sutures tied in an intracorporeal fashion. A blinded rater objectively scored each knot based on a previously published formula (600 minus completion time [sec] minus penalties for accuracy and knot integrity errors). Subjects were stratified according to pretest scores and randomized. The trained group practiced on a videotrainer suturing model until an expert-derived proficiency score (512) was achieved on 12 attempts. The control group received no training. Both the trained and control groups were posttested on the porcine Nissen model. RESULTS: For the training group, mean time to demonstrate simulator proficiency was 151 minutes (range 107 to 224 minutes) and mean number of attempts was 37 (range 24 to 51 attempts). Both the trained and control groups demonstrated significant improvement in overall score from baseline. But the trained group performed significantly better than the control group at posttesting (389 +/- 70 versus 217 +/- 140, p < 0.001), confirming curriculum effectiveness. CONCLUSIONS: These data suggest that training to a predetermined expert level on a videotrainer suture model provides trainees with skills that translate into improved operative performance. Such curricula should be further developed and implemented as a means of ensuring proficiency.

Adult↗

PubMed2005

Multicenter construct validity for southwestern laparoscopic videotrainer stations.

BACKGROUND: The "Southwestern" videotrainer stations have demonstrated concurrent validity (transferability to the operating room). The purpose of this study was to evaluate the Southwestern stations for construct validity (the ability to discriminate between subjects at different levels of experience). MATERIALS AND METHODS: From two surgical training programs, Institutional Review Board approved protocol data were collected from 142 subjects, including novice (medical students and R1, n = 66), intermediate (R2-R4, n = 67), and advanced (R5 and expert surgeons, n = 9) groups. All participants performed three repetitions on each of five stations. Completion time was scored for each task. Laparoscopic experience was determined from residency case log databases and from expert surgeon personal case logs. Results for the three groups were compared using one-way ANOVA, including relevant pair-wise comparisons. Correlations between number of laparoscopic cases performed and task scores were determined by Pearson's and Spearman's rho-correlation coefficients. RESULTS: The mean number of laparoscopic cases performed prior to completing the five tasks was 0 for novices, 9 for intermediates, and 431 for the advanced group. Significant differences (P < 0.001) were noted between groups for all five tasks and composite score. Task scores and composite scores significantly correlated with laparoscopic experience (P < 0.01). CONCLUSION: These data suggest that differences in laparoscopic ability are detected by performance on the videotrainer; thus, construct validity is demonstrated. Moreover, scores accurately reflect laparoscopic experience. Further validation may allow such simulators to be used for testing and credentialing purposes.

Adult↗

PubMed2005

Skill retention following proficiency-based laparoscopic simulator training.

BACKGROUND: Proficiency-based curricula using both virtual reality (VR) and videotrainer (VT) simulators have proven to be efficient and maximally effective, but little is known about the retention of acquired skills. The purpose of this study was to assess skill retention after completion of a validated laparoscopic skills curriculum. METHODS: Surgery residents (n=14) with no previous VR or VT experience were enrolled in an Institutional Review Board-approved protocol and sequentially practiced 12 Minimally Invasive Surgical Trainer-VR and 5 VT tasks until proficiency levels were achieved. One VR (manipulate diathermy) and 1 VT (bean drop) tasks were selected for assessment at baseline, after training completion (posttest), and at retention. RESULTS: All residents completed the curriculum. Posttest assessment occurred at 13.2 +/- 11.8 days and retention assessment at 7.0 +/- 4.0 months. After an early performance decrement at posttest (17%-45%), the acquired skill was maintained up to the end of the follow-up period. For VR, scores were 81.5 +/- 23.5 at baseline, 33.3 +/- 1.8 at proficiency, 48.4 +/- 9.2 at posttest, and 48.4 +/- 11.8 at retention. For VT, scores were 49.4 +/- 12.5 at baseline, 22.0 +/- 1.4 at proficiency, 25.6 +/- 3.6 at posttest, and 26.4 +/- 4.2 at retention. Skill retention was better for VT, compared with VR (P < .02). The extent of skill deterioration did not correlate with training duration or resident level. CONCLUSIONS: Although residents do not retain all acquired skills (more so for VR than for VT) according to simulator assessment, proficiency-based training on simulators results in durable skills. Additional studies are warranted to further optimize curriculum design, investigate simulator differences, and establish training methods that improve skill retention.

Adult↗

PubMed2005

Determining standards for laparoscopic proficiency using virtual reality.

Laparoscopic training using virtual reality has proven effective, but rates of skill acquisition vary widely. We hypothesize that training to predetermined expert levels may more efficiently establish proficiency. Our purpose was to determine expert levels for performance-based training. Four surgeons established as laparoscopic experts performed 11 repetitions of 12 tasks. One surgeon (EXP-1) had extensive Minimally Invasive Surgical Trainer-Virtual Reality (MIST VR) exposure and formal laparoscopic fellowship training. Trimmed mean scores for each were determined as expert levels. A composite score (EXP-C) was defined as the average of all four expert levels. Thirty-seven surgery residents without prior MIST VR exposure and two research residents with extensive MIST VR exposure completed three repetitions of each task to determine baseline performance. Scores for EXP-1 and EXP-C were plotted against the best score of each participant. On average, the EXP-C level was reached or exceeded by 7 of the 37 (19%) residents. In contrast, the EXP-1 level was reached or exceeded by 1 of 37 (3%) residents and both research residents on all tasks. These data suggest the EXP-C level may be too lenient, whereas the EXP-1 level is more challenging and should result in adequate skill acquisition. Such standards should be further developed and integrated into surgical education.

Clinical Competence↗

PubMed2005

Restricted expression of LGR8 in intralaminar thalamic nuclei of rat brain suggests a role in sensorimotor systems.

LGR8 was recently identified as a cognate receptor for insulin-like peptide-3 (INSL3), and INSL3-LGR8 signaling is best known for its role in testis descent during development. LGR8 mRNA has been detected in various human tissues including brain, but the regional and cellular distribution of LGR8 expression in the mammalian central nervous system is unknown. Therefore, in this study we investigated the presence and localization of LGR8 mRNA in rat brain using reverse transcription-polymerase chain reaction and in situ hybridization histochemistry. Results revealed a distinct distribution of LGR8 in forebrain, with transcripts principally restricted to the posterior thalamus and highest densities detected in the parafascicular nucleus of both adult and developing rats. Unexpectedly, INSL3 mRNA was not detected in brain by similar methods, but preliminary electrophysiologic studies of parafascicular neurons revealed that INSL3 altered their activity. These findings suggest that LGR8 signaling may be involved in sensorimotor control in the rat and perhaps other species, particularly via actions on parafascicular neurons that project to basal ganglia and are depleted in Parkinson's disease.

Aging↗

PubMed2005

Detection, localization, and action of the INSL3 receptor, LGR8, in rat kidney.

Recent molecular and pharmacologic studies have identified LGR8, a member of the leucine-rich repeat-containing G-protein-coupled receptor family, as a cognate receptor for insulin-like peptide-3 (INSL3). LGR8 mRNA has been detected in various tissues, but the precise roles of these INSL3-LGR8 systems are unknown. In this study we first investigated the presence and cellular localization of LGR8 mRNA in both adult and developing rat kidney and subsequently examined the possible role of INSL3-LGR8 signaling in cultured mesangial cells. LGR8 mRNA was detected in the kidney by polymerase chain reaction and localized by in situ hybridization in mature glomerular mesangial cells within the renal cortex, with highest levels detected at embryonic day 18 and lowest levels in adult kidney. Synthetic INSL3 inhibited the proliferation of mesangial cells in primary culture, indicating the presence of functional LGR8 on these cells. These findings suggest that INSL3/LGR8 signaling may be involved in the genesis and/or developmental maturation of renal glomeruli and in the regulation of mesangial cell density in the adult kidney.

Aging↗

PubMed2004

Laparoscopic virtual reality training: are 30 repetitions enough?

BACKGROUND: Current literature suggests that novices reach a plateau after two to seven trials when training on the MIST VR laparoscopic virtual reality system. We hypothesize that significant benefit may be gained through additional training. MATERIALS AND METHODS: Second-year medical students (n = 12) voluntarily enrolled under an IRB-approved protocol for MIST VR training. All subjects completed pre- and posttraining questionnaires and performed 30 repetitions of 12 tasks. Performance data were automatically recorded for each trial. Learning curves for each task were generated by fitting spline curves to the mean overall scores for each repetition. Scores were assessed for plateaus by repeated measures, slope, and best score. RESULTS: On average, subjects completed training in 7.1 h. (range, 5.9-9.2). Two to seven performance plateaus were identified for each of the 12 MIST VR tasks. Initial plateaus were found for all tasks by the 8th repetition; however, ultimate plateaus were not reached until 21-29 repetitions. Overall best score was reached between 20 and 30 repetitions and occurred beyond the ultimate plateau for 9 tasks. CONCLUSIONS: These data indicate that a lengthy learning curve exists for novices and may be seen throughout 30 repetitions and possibly beyond. Performance plateaus may not reliably determine training endpoints. We conclude that a significant and variable amount of training may be required to achieve maximal benefit. Neither a predetermined training duration nor an arbitrary number of repetitions may be adequate to ensure laparoscopic proficiency following simulator training. Standards which define performance-based endpoints should be established.

Adult↗

PubMed2003

Laparoscopic totally extraperitoneal versus Lichtenstein herniorrhaphy: cost comparison at teaching hospitals.

Laparoscopic hernia repair is safe and effective and may result in less postoperative pain and faster recuperation compared with traditional open hernia repairs. Controversy exists as to the increased cost associated with laparoscopic repairs. The purpose of this study was to quantify and compare the cost of the totally extraperitoneal (TEP) laparoscopic repair and the tension-free Lichtenstein repair at teaching hospitals. The records of consecutive TEP (n = 28) and Lichtenstein (n = 28) repairs performed at Parkland Memorial Hospital and Zale-Lipshy University Hospital were reviewed. A detailed cost analysis was performed. Total patient charge (5,509 US dollars vs. 3,999 US dollars) and total cost (2,861 US dollars vs. 2,009 US dollars) were higher for TEP versus Lichtenstein repairs, respectively (P < 0.05). Operative time and complications were similar for both groups. Return to full activity (15 vs. 34 days) was faster for TEP versus Lichtenstein repairs, respectively (P < 0.05). Of 9 patients in the TEP group who had previously undergone an open hernia repair, 8 (89%) preferred the laparoscopic approach. The laparoscopic TEP repair costs 852 US dollars more than the Lichtenstein repair. The TEP repair results in faster recuperation. Patient preference and faster recuperation may offset the increased cost associated with laparoscopic hernia repair.

Adult↗

PubMed2002

Do preoperative finger pressures predict early arterial steal in hemodialysis access patients? A prospective analysis.

BACKGROUND: Hand ischemia resulting from arterial steal is a serious complication in patients undergoing hemodialysis access, but specific risk factors for steal remain in dispute. The purpose of this study was to determine whether plethysmographically derived finger pressures (FPs) or digital-brachial indices (DBIs) are predictive of symptomatic arterial steal. METHODS: We prospectively studied 72 patients (37 men, 35 women; mean age, 57 +/- 10 years) who were undergoing brachial artery-based hemodialysis access. All patients had complete pre- and postoperative hand examinations and FP determinations. Surgeons were blinded to preoperative FP results. RESULTS: Prosthetic graft was used in 60 patients (6-mm polytetrafluoroethylene [PTFE] in 50, tapered PTFE in 10), and brachial-based arteriovenous fistulas were created in 12. Fourteen (19%) patients developed arterial steal symptoms. The mean preoperative FP was significantly lower in steal patients than in those without steal (131 +/- 27 vs 151 +/- 31 mm Hg, P <.03). Nine (64%) of the patients with steal had DBIs <1.0, compared to 18 (31%) of the patients without steal (P =.02). However, there was no absolute FP or DBI threshold below which steal was inevitable. The occurrence of steal was attributed to proximal arterial stenoses in seven, to distal arterial disease in five, and was unknown in two. When comparing the 14 patients who developed steal to the 58 who did not, we noted that a higher proportion of steal patients had coronary artery disease (57% vs 17%, P =.005). Steal was more likely to develop in patients with arteriovenous fistulas than in patients with prosthetic grafts (43% vs 14%, P =.009). There were no significant differences in demographic factors, atherosclerotic risks (diabetes, smoking, hypertension, dyslipidemia), prevalence of peripheral vascular disease, cerebrovascular disease, shunt location, tapered vs straight graft, or number of prior grafts placed. CONCLUSIONS: These data indicate that preoperative FPs are lower in patients who develop steal syndrome after hemodialysis access. Patients with preoperative DBIs <1.0 are more likely to develop steal, but there is no DBI threshold below which steal is inevitable. Steal is more likely in patients undergoing brachial-based arteriovenous fistulas than in those receiving prosthetic grafts.

Aged↗