High-level visual-spatial ability for novices correlates with performance in a visual-spatial complex surgical simulator task.

BACKGROUND: This study addresses how high-level visual-spatial ability of surgical novices is related to performance of two simulator tasks with (KSA) and without (MIST) anatomic graphics and haptic feedback, differing in visual-spatial complexity. METHODS: Visual-spatial test scores assessed by Mental Rotation Test (MRT) and BasIQ and performance scores for Instrument Navigation (IN) in Key Surgical Activities (Procedicus KSA) and Manipulate and Diathermy (MD) in Minimally Invasive Surgical Trainer (Procedicus MIST) were correlated for 54 Swedish surgical novices. RESULTS: Significant Pearson's r correlations were obtained between visual-spatial scores measured by MRT-C and total score from the last trial for IN (r = 0.278, p < 0.05). Visual-spatial scores (measured by BasIQ) also correlated with total score from the first trial (r = 0.443, p < 0.05) and from the last trial (r = 0.489, p < 0.05). CONCLUSION: High-level visual-spatial ability is important for surgical novices to possess in the early training phase of a visual-spatial complex task in KSA.

Early exposure to haptic feedback enhances performance in surgical simulator training: a prospective randomized crossover study in surgical residents.

BACKGROUND: In the literature of skill acquisition and transfer of skills, it often is assumed that the rate of skill acquisition depends on what has been learned in a similar context (i.e., surgical simulators providing haptic feedback). This study aimed to analyze whether the addition of haptic feedback early in the training phase for image-guided surgical simulation improves performance. METHODS: A randomized crossover study design was used, in which 38 surgical residents were randomized to begin a 2-h simulator training session with either haptic or nonhaptic training followed by crossover after 1 h. The graphic context was a virtual upper abdomen. The residents performed two diathermy tasks. Two validated tests were used to control for differences in visual-spatial ability: the BasIQ general cognitive ability test and Mental Rotation Test A (MRT-A). RESULTS: After 2 h of training, the group that had started with haptic feedback performed the two diathermy tasks significantly better (p < 0.05, unpaired t-test). Only the group that had started with haptic training significantly improved during the last 1-h session (p < 0.01, paired t-test). CONCLUSION: The findings indicate that haptic feedback could be important in the early training phase of skill acquisition in image-guided surgical simulator training.

Training in tasks with different visual-spatial components does not improve virtual arthroscopy performance.

BACKGROUND: We earlier showed that training in the Procedicus KSA Simulator improves the performance of tasks done later in the same simulator. However, it is still unclear how performance in a specific visual-spatial simulator context may change after training in other simulators with different visual-spatial components. In particular, the aim of this study was to test whether performance in the Procedicus Virtual Arthroscopy (VA) Knee Simulator would remain unchanged after a training session in three other simulators with different visual-spatial components. METHODS: Twenty-eight medical students participated in a quasi-transfer study. They were randomly allocated to an experimental group ( n = 14) and a control group ( n = 14). RESULTS: Performance in the Procedicus VA Knee Simulator did not improve after training in other simulators with different visual-spatial components ( t-test p = NS). No significant correlation was found between the Procedicus VA Knee and the Minimally Invasive Surgical Trainer (MIST) simulators. CONCLUSION: One hour of training in different visual-spatial contexts was not enough to improve the performance in virtual arthroscopy tasks. It cannot be excluded, however, that experienced trainees could improve their performance, because perceived similarity between different situations is influenced by many psychological factors, such as the knowledge or expertise of the person performing the transfer task.

Validation and learning in the Procedicus KSA virtual reality surgical simulator.

BACKGROUND: Advanced simulator training within medicine is a rapidly growing field. Virtual reality simulators are being introduced as cost-saving educational tools, which also lead to increased patient safety. METHODS: Fifteen medical students were included in the study. For 10 medical students performance was monitored, before and after 1 h of training, in two endoscopic simulators (the Procedicus KSA with haptic feedback and anatomical graphics and the established MIST simulator without this haptic feedback and graphics). Five medical students performed 50 tests in the Procedicus KSA in order to analyze learning curves. One of these five medical students performed multiple training sessions during 2 weeks and performed more than 300 tests. RESULTS: There was a significant improvement after 1 h of training regarding time, movement economy, and total score. The results in the two simulators were highly correlated. CONCLUSION: Our results show that the use of surgical simulators as a pedagogical tool in medical student training is encouraging. It shows rapid learning curves and our suggestion is to introduce endoscopic simulator training in undergraduate medical education during the course in surgery when motivation is high and before the development of "negative stereotypes" and incorrect practices.

Adult human osteoblast-like cells do not express insulin-like growth factor-I.

Previous studies using cultures of fetal rodents calvaria have indicated an important role for insulin-like growth factor-I (IGF-I) in the local control of bone formation. In this study, we have examined the expression of IGF-I in adult human osteoblast-like (hOB) cells. To detect very low levels and to distinguish between the two IGF-I mRNA transcripts Ea and Eb, which are formed by alternate splicing, we have used the reverse transcriptase-polymerase chain reaction (RT-PCR). Expression of both Ea and Eb IGF-I mRNA transcripts were found in human liver and in placenta. However, neither Ea nor Eb IGF-I mRNA could be detected under basal conditions or after stimulation with growth hormone in normal hOB cells and two human osteosarcoma cell lines with osteoblastic properties, SaOS-2 and MG-63. We conclude that adult hOB cells do not synthesize IGF-I. Thus, in contrast to its crucial role as a local regulator of skeletal remodeling in fetal rodent bone, IGF-I does not appear to have this autocrine function in adult human bone.

Syntheses of [123I]-, [125I]- and unlabelled (S)-3-iodo-5,6-dimethoxy-N-[(1-ethyl-2-pyrrolidinyl)methyl]salicylamide (NCQ 298), selective ligands for the study of dopamine D-2 receptors.

The salicylamide NCQ 298, (S)-3-iodo-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5,6-dimethoxysalicylami de (4), binds with a high affinity and selectivity to central dopamine D-2 receptors. In the present paper the synthesis of NCQ 298 and the efficient labelling both with 123I and 125I are described. The unlabelled NCQ 298 was synthesized by iodination of (S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-2,5,6-trimethoxybenzamide followed by demethylation with boron tribromide, which produced 4 and the regioisomer 5 in a ratio of 82:18. The two isomeric salicylamides were separated by radial chromatography and tested for their abilities to inhibit the binding of [3H]raclopride to rat striatal membranes in vitro in relation to some representative salicylamides. The 5,6-dimethoxysalicylamide 4 (NCQ 298) was found to be considerably more active than the corresponding 6-methoxysalicylamide 10 (FLA 961 or IBZM). The radioligands [123I]NCQ 298 and [125I]NCQ 298 were prepared in a carrier-free form from the corresponding desiodo compound by the chloramine-T protocol and isolated by semipreparative HPLC. The total radiochemical yields of [123I]NCQ 298 and [125I]NCQ 298 (based on [123I]- and [125I]iodide and decay-corrected) were 88% and 93%, respectively, with a radiochemical purity of greater than 99%. [125I]NCQ 298 will be studied to evaluate its potential as a radioligand in studies requiring a high specific activity, selectivity and high potency to label dopamine D-2 receptors. [123I]NCQ 298 has potential as a radioligand for the in vivo examination of central dopamine D-2 receptors in human brain by Single Photon Emission Computed Tomography (SPECT).

Alcoholic hepatitis in females.

In the period 1970-1984 alcoholic hepatitis was diagnosed by liver biopsy in 52 females. Thirty-six patients with cirrhosis were generally in a worse clinical and biochemical state than those without cirrhosis. Biochemical tests for liver function showed significant improvement from admission to the time of liver biopsy. At follow-up liver function tests were generally better in patients who had stopped drinking alcohol compared to those who continued to do so. The 5-year survival rate was 82% for females without cirrhosis, and 45% for those with cirrhosis (p less than 0.03). Considering the sex-related differences in alcohol abuse in the general population we found no evidence of increased susceptibility to the hepatotoxic effect of alcohol in females.

The diagnostic value of alpha 1-antitrypsin globules in liver cells as a morphological marker of alpha 1-antitrypsin deficiency.

In order to determine the diagnostic value of alpha 1-antitrypsin (AAT) globules as a morphological marker of AAT-deficiency of the Pi-Z type, liver needle biopsies from a prospective series of 600 patients were stained with PAS after pretreatment with diastase and by indirect immunoperoxidase staining for AAT deposits. Serum AAT phenotypes of the patients were determined by means of isoelectric focusing. Thirty-two biopsies were from patients with the Pi-Z allele (31 MZ, 1 Z), and 568 biopsies from patients without the Pi-Z allele. AAT globules larger than 3 micron were found in 16 biopsies of which 15 were from patients with the Pi-Z allele (diagnostic specificity 0.94), whereas 20 of 26 biopsies with AAT globules larger than 1 micron were from Pi-Z patients (diagnostic specificity 0.77). Only 47% of the biopsies from patients with the Pi-Z allele contained AAT globules larger than 3 micron. Thus, although AAT globules larger than 3 micron are highly specific as a morphological marker of the Pi-Z allele, their rather infrequent occurrence in carriers of the Pi-Z allele indicates that all investigations concerning the correlation between AAT deficiency of the Pi-Z type and liver disease should be based on phenotyping of sera from all the patients.

Extraperitoneal versus transperitoneal drainage of the intra-abdominal abscess.

Controversy as to whether the intra-abdominal abscess should be drained extraperitoneally or through formal laparotomy still rages. Arguments for a transperitoneal approach include no need to identify specific locus preoperatively and uniform drainage of all abscesses, especially any otherwise unrecognized pus collection. Proponents for the extraperitoneal route stress failure to contaminate previously uninvolved peritoneal spaces and more reliable avoidance of injury to intestine, predisposing to subsequent intestinal fistula. To resolve this impasse, a prospective study of each method was based upon a schedule of previously randomized treatment options. After 32 months of study, 60 patients had been enrolled without obvious differences between treatment groups with respect to demographic features, preoperative definition and locus of infection, precipitating cause of sepsis, associated diseases, responsible bacteria and antibiotic therapy. With the transperitoneal approach, five patients had hollow viscus injury, while seven eventually had an intestinal fistula develop, causing major problems in four. Despite no obvious intestinal injury with the extraperitoneal route, two transient intestinal fistulas did occur. Seven patients drained transperitoneally had additional abscesses discovered, yet another operation was required to drain at least one complicating abscess in seven of this same group. With the extraperitoneal route, only two patients needed reoperation to drain another abscess. Although there were more deaths and complications in the group drained transperitoneally, morbidity (47 per cent) and mortality (7 per cent) were not significantly different statistically. Such data refute the professed superiority of a transperitoneal approach to intra-abdominal abscess drainage, both from need to reoperative for second abscess as well as incidence of latter intestinal fistula. Best results were noted with abscess identification through computerized tomography followed by extraperitoneal drainage.

Ceftriaxone versus combined gentamicin and clindamycin for polymicrobial surgical sepsis.

During a 7 month trial for therapy of polymicrobial surgical sepsis, intravenous antibiotic treatment was randomized between gentamicin (1 mg/kg every 8 hours) plus clindamycin (8 mg/kg every 6 hours), and the cephalosporin, ceftriaxone (1 g every 12 hours) in 197 patients, of whom 99 were being treated for peritonitis, 93 for soft tissue sepsis, and 5 for other forms of infection. No significant differences were noted in patient demographics, type of sepsis, associated disease states, surgical procedure, or causative aerobic or anaerobic pathogens. Results demonstrated approximately equivalent efficacy, although cure rates obtained with ceftriaxone in patients with soft tissue sepsis or intraabdominal abscess were superior to those achieved with combination gentamicin and clindamycin. There were no significant side effects with ceftriaxone therapy, such as the renal failure noted in six of the patients treated with gentamicin and clindamycin. We conclude that single agent treatment with ceftriaxone is preferable because of the greater safety and the longer dosing intervals.

Safety of incidental appendectomy.

Reports in the surgical literature are conflicting as to whether appendectomy "in passing" during laparotomy for trauma or for some other disease state does or does not significantly increase patient morbidity or mortality. A chart survey of all appendectomies (342 for acute appendicitis and 146 as incidental procedures) performed on the trauma service of Grady Memorial Hospital over a 40 month period appeared to indicate that the wound infection rate (6.8 percent) was the same as that for acute simple or suppurative appendicitis (6.7 percent), whereas the intraabdominal sepsis rate (17.5 percent) paralleled that for more advanced gangrenous or perforative appendicitis (18.6 percent). Since the validity of a retrospective review is always open to question, a prospective, randomized trial was carried out only on patients with a negative abdominal exploration for trauma over a 22 month interval at the same trauma service. An odd second from the last digit hospital number dictated appendectomy, provided the appendix was readily accessible; an even digit in the same locus dictated retention of the appendix. In no patient did intraperitoneal sepsis develop, regardless of the procedure chosen. Wound infection rates were 1.8 percent for appendectomy (1 of 56), if local anatomic considerations precluded an easy appendectomy (0 of 45), and 3.6 percent for the control subjects without appendectomy (3 of 83). There were no deaths. These data cast considerable doubt on the reliability of retrospective reviews and support the generally accepted dictum that incidental appendectomy, especially in the trauma patient, can be a relatively innocuous procedure.

Management of the major coagulopathy with onset during laparotomy.

An experience with 31 patients who developed major bleeding diatheses during laparotomy was reviewed. Management of the initial 14 patients was by standard hematologic replacement, completion of all facets of operation, and then closure of the peritoneal cavity, usually with suction drainage; only one patient survived. The subsequent 17 patients had laparotomy terminated as rapidly as possible to avoid additional bleeding. Major vessel injuries were repaired; ends of resected bowel were ligated; and holes in other gastrointestinal segments and the bladder were closed by purse-string sutures. One patient had a ureter ligated. Laparotomy pads (4-17) were then packed within the abdomen to effect tamponade, and the abdomen was closed under tension without drains or stomata. Following correction of the coagulopathy, the abdomen was re-explored at 15 to 69 hours in the 12 survivors. Definitive surgery then was completed: bowel resection and reanastomosis; ureter reimplantation; drains for bile, pancreatic juice, and urine; and stomata for bowel or urine diversion or decompression. Eleven of 17 patients, deemed to have a lethal coagulopathy, survived. This technique of initial abortion of laparotomy, establishment of intra-abdominal pack tamponade, and then completion of the surgical procedure once coagulation has returned to an acceptable level has proven to be lifesaving in previously non-salvageable situations.

Third-generation cephalosporins for polymicrobial surgical sepsis.

During 31 months of study, 808 patients with polymicrobial surgical infection were randomized for antibiotic therapy between a third-generation cephalosporin (moxalactam disodium [149], cefotaxime sodium [125], and cefoperazone sodium [141]) and the combination of gentamicin sulfate plus clindamycin (393). Results based on antibiotic therapy included the following: cure in 83% given cephalosporin, 73% with antibiotic combination; control but recurrent sepsis in 7% and 15%; and failure in 4% and 8%, respectively. Such data support the tenet that third-generation cephalosporins are at least equal, if not superior, to the combination of gentamicin plus clindamycin for treatment of polymicrobial surgical sepsis.

A technique for transduodenal sphincteroplasty.

A technique for transduodenal sphincteroplasty is presented. T-tube decompression of the common bile duct and subphrenic space drainage are routinely avoided. To date, results in 123 consecutive patients have been excellent. The single most troublesome wound complication, duodenal fistula, had been avoided in the most recent 68 patients by colonic or omental onlay of serosa.

Colonic atony in association with sigmoid volvulus: its role in recurrence of obstructive symptoms.

We reviewed a 30-year experience in management of 129 patients with 163 acute obstructions due to sigmoid volvulus. Recurrent obstruction of the colon was observed in 47 (or 45%) of 104 patients who survived their initial obstructive episode: 61% after rectal tube insertion, 45% after detorsion, 33% after sigmoid plication, and 21% despite sigmoid colectomy. Subsequent barium enema or surgical exploration showed true sigmoid volvulus to be the cause of recurrent obstruction in 36 of 47 patients, while atonic bowel, involving the sigmoid alone or more proximal colon as well, was responsible for the other 11 recurrent obstructions. Sigmoid excision was corrective only if bowel atony was limited to that portion of the colon. Only more extensive colectomy, so as to include all flaccid colon, consistently obviated recurrence. Failure to recognize functional obstruction accounted for five of the 25 total deaths.