Markov modeling of minimally invasive surgery based on tool/tissue interaction and force/torque signatures for evaluating surgical skills.

The best method of training for laparoscopic surgical skills is controversial. Some advocate observation in the operating room, while others promote animal and simulated models or a combination of surgery-related tasks. A crucial process in surgical education is to evaluate the level of surgical skills. For laparoscopic surgery, skill evaluation is traditionally performed subjectively by experts grading a video of a procedure performed by a student. By its nature, this process uses fuzzy criteria. The objective of the current study was to develop and assess a skill scale using Markov models (MMs). Ten surgeons [five novice surgeons (NS); five expert surgeons (ES)] performed a cholecystectomy and Nissen fundoplication in a porcine model. An instrumented laparoscopic grasper equipped with a three-axis force/torque (F/T) sensor was used to measure the forces/torques at the hand/tool interface synchronized with a video of the tool operative maneuvers. A synthesis of frame-by-frame video analysis and a vector quantization algorithm, allowed to define F/T signatures associated with 14 different types of tool/tissue interactions. The magnitude of F/T applied by NS and ES were significantly different (p < 0.05) and varied based on the task being performed. High F/T magnitudes were applied by NS compared with ES while performing tissue manipulation and vise versa in tasks involved tissue dissection. From each step of the surgical procedures, two MMs were developed representing the performance of three surgeons out of the five in the ES and NS groups. The data obtained by the remaining two surgeons in each group were used for evaluating the performance scale. The final result was a surgical performance index which represented a ratio of statistical similarity between the examined surgeon's MM and the MM of NS and ES. The difference between the performance index value, for a surgeon under study, and the NS/ES boundary, indicated the level of expertise in the surgeon's own group. Using this index, 87.5% of the surgical procedures were correctly classified into the NS and ES groups. The 12.5% of the procedures that were misclassified were performed by the ES and classified as NS. However in these cases the performance index values were very close to the NS/ES boundary. Preliminary data suggest that a performance index based on MM and F/T signatures provides an objective means of distinguishing NS from ES. In addition, this methodology can be further applied to evaluate haptic virtual reality surgical simulators for improving realism in surgical education.

The causes of fever in children attending hospital in the north of England.

OBJECTIVES: Fever is a common symptom in children presenting to casualty. Identifying the seriously ill is difficult. Previous studies, mainly from North America, suggest that symptoms, signs and simple investigations may help to do this. The aim of the present study was to assess the causes of fever and identify clinical and laboratory features suggesting serious disease in U.K. children presenting to hospital with temperatures >or=38 degrees C. METHODS: All children with a temperature of >or=38 degrees C seen in two hospitals between August and October 1999. RESULTS: One hundred and forty one children between 8 days and 16 years of age were studied, 64% male, 55% aged under 2 years. Eighty three percent had temperatures between 38 and 39 degrees C. Ninety six percent were casualty or GP referrals and 4% were tertiary referrals. Twenty nine percent (41/141) had serious disease but microbiologically or radiologically proven in only 22% (31/141); pneumonia (nine), meningitis (seven), sepsis (five), urinary tract infection (five), brain abscess (two), toxic shock syndrome (one), appendicitis (one), ischiorectal abscess (one). Forty two percent (5/12) of microbiologically proven meningitis and sepsis and 36% (8/22) of all meningitis and sepsis were meningococcal. Seventy one percent had non-serious diseases. In cases of serious disease the temperature was >39 degrees C in 15% (sensitivity: 14%, specificity: 82%, PPV: 25%). Poor feeding and restlessness predicted serious disease with a sensitivity of 78% and 76%, respectively. Full blood count (FBC) was taken in 50% of patients on admission; in 44% of serious and 24% of non-serious diseases WBC was between 5000 and 15,000/mm(3) and WBC >or=15,000/mm(3) was seen in 39% of serious diseases (sensitivity:10%, specificity: 95%, PPV: 44%). CONCLUSIONS: One out of three of children referred with fever had a serious disease. Degree of temperature and WBC count were poor predictors of serious disease. Interestingly, poor feeding and restlessness were more sensitive predictors, suggesting high fever and WBC count can not replace clinical assessment of the child with a temperature.

Laparoscopic prosthetic reinforcement of hiatal herniorrhaphy.

BACKGROUND/AIMS: Primary repair of a large hiatal hernia is associated with a published recurrence rate of up to 10%; anecdotal rates even higher than this have been reported to the authors. The use of prosthetic material in the repair of other abdominal wall defects has often produced better results than primary repair. We wanted to compare laparoscopic primary repair of large hiatus hernias with laparoscopic primary repair reinforced with prosthetic. METHODS: Thirty-one patients with symptomatic gastroesophageal reflux and a hiatal defect 8 cm or greater were randomized to Nissen fundoplication with posterior cruroplasty (n = 16) or Nissen cruroplasty, and onlay of polytetrafluoroethylene (PTFE) mesh (n = 15). All patients underwent preoperative esophagogastroduodenoscopy (EGD) and barium esophagography. After posterior cruroplasty with interrupted nonabsorbable suture, the mesh reinforcement group had an onlay of PTFE placed around the hiatus. A radial slit with 3 cm 'keyhole' (to accommodate the esophagus) was cut into the PTFE. The prosthetic was stapled to the diaphragm, and the two leaves of the slit were stapled to each other. All patients underwent EGD at 3 months and all had esophagrams every 6 months postoperatively. Follow-up ranged from 12 to 36 months. RESULTS: Length of hospital stay was equal in both groups (2 days). The average cost to the patient with PTFE was USD 1,050 higher than to the patient with primary repair. There were 2 complications (1 pneumonia, 1 urinary retention) in the PTFE group, and 1 complication (pneumothorax) in the primary repair group. There were 3 recurrences (18.8%) in the primary group (p = 0.08, chi(2) test). CONCLUSION: The use of PFTE reinforcement for primary repair of large hiatal hernias may result in a lower rate of recurrent herniation compared to primary repair alone.

Laparoscopic repair of large hiatal hernia with polytetrafluoroethylene.

BACKGROUND: Several studies have shown that large hiatal hernias are associated with a high recurrence rate. Despite the problem of recurrence, the technique of hiatal herniorrhaphy has not changed appreciably since its inception. In this 3-year study we have evaluated laparoscopic hiatal hernia repair in individuals with a hernia defect greater than 8 cm in diameter. METHODS: A series of 35 patients with sliding or paraesophageal hiatal hernias was prospectively randomized to hiatal hernia repair with (n = 17) or without (n = 18) polytetrafluoroethylene (PTFE). All patients had an endoscopic and radiographic diagnosis of large hiatal hernia. Both repairs were performed by using interrupted stitches to approximate the crurae. In the group randomized to repair with prosthesis, PTFE mesh with a 3-cm "keyhole" was positioned around the gastroesophageal junction with the esophagus through the keyhole. The PTFE was stapled to the diaphragm and crura with a hernia stapler. RESULTS: Patients were followed with EGD and esophagogram at 3 months postoperatively, and with esophagogram every 6 months thereafter. Individuals with PTFE had a longer operation time, but the 2-day hospital stay was the same in both groups. The cost of the repair was $1050 +/- $135 more in the group with the prosthesis. There were two complications (1 pneumonia, 1 urinary retention) in the group repaired with PTFE and one complication (pneumothorax) in the group without prosthesis. The group without PTFE was notable for three (16.7%) recurrences within the first 6 months of surgery. CONCLUSION: On the basis of these preliminary results it appears that repair with PTFE may confer an advantage, with lower rates of recurrence in patients with large hiatal hernia defects.

Detection of pneumocystis DNA in nasopharyngeal aspirates of leukaemic infants with pneumonia.

The technique of polymerase chain reaction was used to detect Pneumocystis carinii DNA in nasopharyngeal secretions of three infants with leukaemia who had the clinical features of P carinii pneumonia. The use of this non-invasive technique allowed the early diagnosis and treatment of these infants whose protocols did not include the use of prophylactic co-trimoxazole.

Frontoethmoidal meningoencephalocele: a common and severe congenital abnormality in South East Asia.

The clinical features of 23 cases of fronto-ethmoidal meningoencephalocele are described in two South East Asian populations. The clinical, embryological, and epidemiological evidence may support an early teratogenic insult in the aetiology of this congenital defect.

Eating attitudes in an adolescent schoolgirl population.

One thousand five hundred and fourteen Auckland school girls in the age range 13 to 17 were given an eating attitudes test. Fourteen percent of this large population produced a score on that test of greater than 30 which has been claimed to be indicative of potential eating disorder. We view this incidence with alarm and make commentary on the social process of coupling the thin feminine body ideal with success.

Field trials of bromadiolone against infestations of warfarin-resistant Rattus norvegicus.

Baiting with 0.005% bromadiolone in medium oatmeal or soaked wheat completely controlled infestations of warfarin-resistant rats on farms when surplus amounts of the poisoned baits were maintained until rats ceased to feed on them. The speed with which control was achieved was the same as with other anticoagulants that have been tested in this way.Poison baiting with 0.005% bromadiolone for only 1, 4 or 7 days achieved respectively about 49, 77 and 81% control of similar farm rat infestations.

Laboratory and field evaluation of pyriminyl as a poison for Rattus norvegicus.

Laboratory tests indicated that the optimum concentration for pyriminyl in rat baits was between 1% and 3%. In field trials in which 0.5% pyriminyl (the concentration in commercial use) was compared with 2.5% zinc phosphide for the control of rats on farms, the pyriminyl treatments were significantly less effective than the zinc phosphide even when the poisoned baits were left down for 7 days instead of 1 day after prebaiting. Both poisons were as effective in medium oatmeal bait as they were in medium oatmeal containing 5% corn oil and 5% sugar.