Perioperative mortality in bariatric surgery: meta-analysis

BACKGROUND

Bariatric surgery is an established treatment for severe obesity; however, fewer than 1 per cent of eligible patients undergo surgery. The perceived risk of surgery may contribute to the low uptake. The aim of this study was to determine perioperative mortality associated with bariatric surgery, comparing different operation types and data sources.

METHODS

A literature search of Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials was conducted to identify studies published between 1 January 2014 and 31 July 2020. Inclusion criteria were studies of at least 1000 patients reporting short-term mortality after bariatric surgery. Data were collected on RCTs. Meta-analysis was performed to establish overall mortality rates across different study types. The primary outcome measure was perioperative mortality. Different operation types were compared, along with study type, in subgroup analyses. The study was registered at PROSPERO (2019: CRD 42019131632).

RESULTS

Some 4356 articles were identified and 58 met the inclusion criteria. Data were available on over 3.6 million patients. There were 4707 deaths. Pooled analysis showed an overall mortality rate of 0.08 (95 per cent c.i. 0.06 to 0.10; 95 per cent prediction interval 0 to 0.21) per cent. In subgroup analysis, there was no statistically significant difference between overall, 30-day, 90-day or in-hospital mortality (P = 0.29). There was no significant difference in reported mortality for RCTs, large studies, national databases or registries (P = 0.60). The pooled mortality rates by procedure type in ascending order were: 0.03 per cent for gastric band, 0.05 per cent for sleeve gastrectomy, 0.09 per cent for one-anastomosis gastric bypass, 0.09 per cent for Roux-en-Y gastric bypass, and 0.41 per cent for duodenal switch (P < 0.001 between operations).

CONCLUSION

Bariatric surgery is safe, with low reported perioperative mortality rates.

Defining global benchmarks in elective secondary bariatric surgery comprising conversional, revisional and reversal procedures

Objective

Management of poor response and of long-term complications after bariatric surgery (BS) is complex and under-investigated. Indications and types of reoperations vary widely and postoperative complication rates are higher compared to primary BS. Benchmarking uses best performance in a given field as reference point for improvement. Our aim was to define ‘‘best possible’’ outcomes for elective secondary BS.

Methods

The establishment of benchmarks in secondary BS followed a standardized methodology, based on recommendations of a Delphi consensus panel of experts. This multicenter study analyzed patients undergoing elective secondary BS in 18 high-volume centers on 4 continents from 06/2013 to 05/2019. Twenty-one outcome benchmarks were established in low-risk patients, defined as the 75th percentile of the median outcome values of the centers. Benchmark cases had no: previous laparotomy, diabetes, sleep apnea, cardiopathy, renal insufficiency, inflammatory bowel disease, immunosuppression, history of thromboembolic events, BMI&gt;50kg/m2 or age&gt;65 years. Descriptive statistics, multivariate logistic regression and data visualization were performed using the R software.

Results

Out of 44’884 elective bariatric procedures performed in the participating centers, 5’328 secondary BS cases were identified. The benchmark cohort included 3143 cases, mainly females (85%), aged 43.8±10 years, 8.4±5.3 years after primary BS, with a body mass index 35.2±7kg/m2. Main indications were insufficient weight loss (43%) and gastro-esophageal reflux disease/dysphagia (25%). 90-days postoperatively, 14.57% of benchmark patients presented ≥1 complication, mortality was 0.06% (n = 2). Significantly higher morbidity was observed in non-benchmark cases (OR 1.36) and after conversional or revisional procedures with gastrointestinal suture/stapling (OR 1.7). Benchmark cutoffs at 90-days postoperatively were ≤5.8% re-intervention and ≤8.8% re-operation rate. At 2-years (IQR 1-3) 15.6% of benchmark patients required a reoperation.

Conclusion

Secondary BS is safe, although postoperative morbidity exceeds the established benchmarks for primary BS. The excess morbidity is due to an increased risk of gastrointestinal leakage and higher need for intensive care. The considerable rate of tertiary BS warrants expertise and future research to optimize the management of non-success after BS.

From the Knife to the Endoscope-a History of Bariatric Surgery

PURPOSE OF REVIEW

Current bariatric surgical practice has developed from early procedures, some of which are no longer routinely performed. This review highlights how surgical practice in this area has developed over time.

RECENT FINDINGS

This review outlines early procedures including jejuno-colic and jejuno-ileal bypass, initial experience with gastric bypass, vertical banded gastroplasty and biliopancreatic diversion with or without duodenal switch. The role laparoscopy has played in the widespread utilization of surgery for treatment of obesity will be described, as will the development of procedures which form the mainstay of current bariatric surgical practice including gastric bypass, sleeve gastrectomy and adjustable gastric banding. Endoscopic therapies for the treatment of obesity will be described. By outlining how bariatric surgical practice has developed over time, this review will help practicing surgeons understand how individual procedures have evolved and also provide insight into potential future developments in this field.

Benefits of barbed suture utilisation in gastrointestinal anastomosis: a systematic review and meta-analysis

INTRODUCTION

Anastomosis formation constitutes a critical aspect of many gastrointestinal procedures. Barbed suture materials have been adopted by some surgeons to assist in this task. This systematic review and meta-analysis compares the safety and efficacy of barbed suture material for anastomosis formation compared with standard suture materials.

METHODS

An electronic search of Embase, Medline, Web of Science and Cochrane databases was performed. Weighted mean differences were calculated for effect size of barbed suture material compared with standard material on continuous variables and pooled odds ratios were calculated for discrete variables.

FINDINGS

There were nine studies included. Barbed suture material was associated with a significant reduction in overall operative time (WMD: -12.87 (95% CI = -20.16 to -5.58) (P = 0.0005)) and anastomosis time (WMD: -4.28 (95% CI = -6.80 to -1.75) (P = 0.0009)). There was no difference in rates of anastomotic leak (POR: 1.24 (95% CI = 0.89 to 1.71) (P = 0.19)), anastomotic bleeding (POR: 0.80 (95% CI = 0.29 to 2.16) (P = 0.41)), or anastomotic stricture (POR: 0.72 (95% CI = 0.21 to 2.41) (P = 0.59)).

CONCLUSIONS

Use of barbed sutures for gastrointestinal anastomosis appears to be associated with shorter overall operative times. There was no difference in rates of complications (including anastomotic leak, bleeding or stricture) compared with standard suture materials.

Incidence and risk factors for esophageal cancer following achalasia treatment: national population-based case-control study

The objective of this study is to identify the incidence of and risk factors associated with the development of esophageal cancer in treated achalasia patients in a national cohort. Patients with esophageal achalasia diagnosed and receiving a treatment between 2002 and 2012 were identified in England. Patient and treatment factors were compared between individuals who developed esophageal cancer and those that did not using univariate and multivariate analyses. A total of 7487 patients receiving an interventional treatment for esophageal achalasia were included and 101 patients (1.3%) developed esophageal cancer. The incidence of esophageal cancer was 205 cases per 100,000 patient years at risk. Patients who developed esophageal cancer were older and more commonly primarily treated with pneumatic dilation (82.2% vs. 60.3%; P < 0.001). In the esophageal cancer group, there was an increase in the number of patients requiring reinterventions (47.5% vs. 38.0%; P = 0.041) and the average total number of reinterventions per patient (1.2 vs. 0.8; P = 0.026). Multivariate analysis suggested associations between increased reintervention following both surgical myotomy (HR = 5.1; 95%CI 1.12-23.16) and pneumatic dilation (HR = 1.48; 95%CI 0.95-2.29), and esophageal cancer risk. Increasing patient age and reintervention following primary achalasia treatment are important potential risk factors for the development of esophageal cancer. Treated achalasia patients with symptom recurrence should be carefully evaluated for potential development of esophageal cancer prior to considering reintervention, and increased vigilance may help diagnose esophageal cancer in these individuals at an early stage.

The influence of hospital volume upon clinical management and outcomes of esophageal achalasia: an English national population-based cohort study

Management of achalasia is potentially complex. Previous studies have identified equivalence between pneumatic dilatation and surgical cardiomyotomy in terms of clinical outcomes. However, previous research has not investigated whether a management strategies and outcomes are different in high-volume achalasia centers. This national population-based cohort study aimed to identify the treatment modalities utilized in centers, which regularly manage achalasia and those which manage it infrequently. This study also assessed rates of re-intervention and complications to establish if a volume-outcome relationship exists for the management of achalasia in England. In this study, the Hospitals Episode Statistics database was used to identify all patients treated for achalasia in England from 2002 to 2012. Primary treatment was defined as surgical cardiomyotomy, sequential pneumatic dilatation, or botulinum toxin therapy. Primary outcome measure was reintervention. Centers were divided into regular achalasia centers (≥5.7 cases per annum) and infrequent achalasia centers (<5.7 cases per annum), and were analyzed according to tertiary cancer center status. In total, there were 7,487 patients treated for achalasia. Out of 1,947 cases (26%) were treated in regular achalasia centers, with 5,540 (74%) treated in infrequent centers. In binary logistic regression modeling regular centers treated a similar proportion of patients with primary surgical cardiomyotomy (OR: 1.11 (95% CI 0.98-1.27)) and had similar rates of re-intervention to infrequent achalasia centers (HR: 1.03 (0.94-1.12)). RA-CUSUM analysis demonstrated no relationship between total hospital volume and reintervention rates. Tertiary cancer centers treated more achalasia patients with primary surgical cardiomyotomy (OR: 1.51 (95% CI 1.31-1.73)) but there was no significant difference in reintervention rates (OR: 1.05 (95% CI 0.95-1.16)). In conclusion, this analysis failed to demonstrate a volume-outcome relationship in the management of achalasia in England. This study highlights that achalasia is treated infrequently by the majority of centers.

An observational study of the timing of surgery, use of laparoscopy and outcomes for acute cholecystitis in the USA and UK

BACKGROUND

Evidence supports early laparoscopic cholecystectomy for acute cholecystitis. Differences in treatment patterns between the USA and UK, associated outcomes and resource utilization are not well understood.

METHODS

In this retrospective, observational study using national administrative data, emergency patients admitted with acute cholecystitis were identified in England (Hospital Episode Statistics 1998-2012) and USA (National Inpatient Sample 1998-2011). Proportions of patients who underwent emergency cholecystectomy, utilization of laparoscopy and associated outcomes including length of stay (LOS) and complications were compared. The effect of delayed treatment on subsequent readmissions was evaluated for England.

RESULTS

Patients with a diagnosis of acute cholecystitis totaled 1,191,331 in the USA vs. 288 907 in England. Emergency cholecystectomy was performed in 628,395 (52.7% USA) and 45,299 (15.7% England) over the time period. Laparoscopy was more common in the USA (82.8 vs. 37.9%; p < 0.001). Pre-treatment (1 vs. 2 days; p < 0.001) and total ( 4 vs. 7 days; p < 0.001) LOS was lower in the USA. Overall incidence of bile duct injury was higher in England than the USA (0.83 vs. 0.43%; p < 0.001), but was no different following laparoscopic surgery (0.1%). In England, 40.5% of patients without an immediate cholecystectomy were subsequently readmitted with cholecystitis. An additional 14.5% were admitted for other biliary complications, amounting to 2.7 readmissions per patient in the year following primary admission.

CONCLUSION

This study highlights management practices for acute cholecystitis in the USA and England. Despite best evidence, index admission laparoscopic cholecystectomy is performed less in England, which significantly impacts subsequent healthcare utilization.

Influence of national centralization of oesophagogastric cancer on management and clinical outcome from emergency upper gastrointestinal conditions

Background

In England in 2001 oesophagogastric cancer surgery was centralized. The aim of this study was to evaluate whether centralization of oesophagogastric cancer to high-volume centres has had an effect on mortality from different emergency upper gastrointestinal conditions.

Methods

The Hospital Episode Statistics database was used to identify patients admitted to hospitals in England (1997–2012). The influence of oesophagogastric high-volume cancer centre status (20 or more resections per year) on 30- and 90-day mortality from oesophageal perforation, paraoesophageal hernia and perforated peptic ulcer was analysed.

Results

Over the study interval, 3707, 12 441 and 56 822 patients with oesophageal perforation, paraoesophageal hernia and perforated peptic ulcer respectively were included. There was a passive centralization to high-volume cancer centres for oesophageal perforation (26·9 per cent increase), paraoesophageal hernia (19·5 per cent increase) and perforated peptic ulcer (23·0 per cent increase). Management of oesophageal perforation in high-volume centres was associated with a reduction in 30-day (HR 0·58, 95 per cent c.i. 0·45 to 0·74) and 90-day (HR 0·62, 0·49 to 0·77) mortality. High-volume cancer centre status did not affect mortality from paraoesophageal hernia or perforated peptic ulcer. Annual emergency admission volume thresholds at which mortality improved were observed for oesophageal perforation (5 patients) and paraoesophageal hernia (11). Following centralization, the proportion of patients managed in high-volume cancer centres that reached this volume threshold was 88·0 per cent for oesophageal perforation, but only 30·3 per cent for paraoesophageal hernia.

Conclusion

Centralization of low incidence conditions such as oesophageal perforation to high-volume cancer centres provides a greater level of expertise and ultimately reduces mortality.

Anastomotic reinforcement with omentoplasty following gastrointestinal anastomosis: A systematic review and meta-analysis

Anastomotic leak is a potentially devastating complication following gastrointestinal anastomosis. Some surgeons believe that reinforcing the anastomosis with omentum reduces the incidence and severity of anastomotic leak. A comprehensive electronic search of EMBASE, Medline, Web of Science and Cochrane databases was performed. Pooled odds ratios (POR) were calculated for discrete variables. There were six studies investigating esophageal anastomosis and 3 studies investigating colorectal anastomosis identified by the literature search. A total of 2296 patients were included, 1073 with omentoplasty and 1223 without. In esophageal surgery omentoplasty significantly reduced the rate of anastomotic leak (2.9% vs 10.5% (POR = 0.28; 95% CI = 0.17 to 0.47; P < 0.0001), but there was no significant effect upon in-hospital mortality (2.3% vs. 2.5%; POR = 0.911 [95% CI 0.439-1.887]; P = 0.802) or anastomotic stricture between the two groups (6.6% vs 9.1%; POR = 0.842 [95% CI 0.331 to 2.145]; P = 0.720). In colorectal surgery there was no significant difference in anastomotic leak rate (5.0% vs 8.4%; POR: 0.50; 95% CI 0.21 to 1.17) or in-hospital mortality (4.2% vs 4.1%; POR: 0.90; 95% CI 0.34 to 2.41). The results of this analysis show that omentoplasty significantly reduced the rate of anastomotic leak following esophageal anastomosis but these results were not observed in colorectal anastomosis. Omentoplasty could be used as an adjunct technique to reduce the incidence of anastomotic leak in oesophageal anastomosis.

Differential susceptibility of primary cultured human skin cells to hypericin PDT in an in vitro model

Skin cancer is the most common cancer worldwide, and its incidence rate in South Africa is increasing. Photodynamic therapy (PDT) has been shown to be an effective treatment modality, through topical administration, for treatment of non-melanoma skin cancers. Our group investigates hypericin-induced PDT (HYP-PDT) for the treatment of both non-melanoma and melanoma skin cancers. However, a prerequisite for effective cancer treatments is efficient and selective targeting of the tumoral cells with minimal collateral damage to the surrounding normal cells, as it is well established that cancer therapies have bystander effects on normal cells in the body, often causing undesirable side effects. The aim of this study was to investigate the cellular and molecular effects of HYP-PDT on normal primary human keratinocytes (Kc), melanocytes (Mc) and fibroblasts (Fb) in an in vitro tissue culture model which represented both the epidermal and dermal cellular compartments of human skin. Cell viability analysis revealed a differential cytotoxic response to a range of HYP-PDT doses in all the human skin cell types, showing that Fb (LD50=1.75μM) were the most susceptible to HYP-PDT, followed by Mc (LD50=3.5μM) and Kc (LD50>4μM HYP-PDT) These results correlated with the morphological analysis which displayed distinct morphological changes in Fb and Mc, 24h post treatment with non-lethal (1μM) and lethal (3μM) doses of HYP-PDT, but the highest HYP-PDT doses had no effect on Kc morphology. Fluorescent microscopy displayed cytoplasmic localization of HYP in all the 3 skin cell types and additionally, HYP was excluded from the nuclei in all the cell types. Intracellular ROS levels measured in Fb at 3μM HYP-PDT, displayed a significant 3.8 fold (p<0.05) increase in ROS, but no significant difference in ROS levels occurred in Mc or Kc. Furthermore, 64% (p<0.005) early apoptotic Fb and 20% (p<0.05) early apoptotic Mc were evident; using fluorescence activated cell sorting (FACS), 24h post 3μM HYP-PDT. These results depict a differential response to HYP-PDT by different human skin cells thus highlighting the efficacy and indeed, the potential bystander effect of if administered in vivo. This study contributes toward our knowledge of the cellular response of the epidermis to photodynamic therapies and will possibly enhance the efficacy of future photobiological treatments.

Use of the surgical Apgar score to guide postoperative care

INTRODUCTION

The surgical Apgar score (SAS) can predict 30-day major complications or death after surgery. Studies have validated the score in different patient populations and suggest it should be used to objectively guide postoperative care. We aimed to see whether using the SAS in a decisive approach in a future randomised controlled trial (RCT) would be likely to demonstrate an effect on postoperative care and clinical outcome.

METHODS

A total of 143 adults undergoing general/vascular surgery in 9 National Health Service hospitals were recruited to a pilot single blinded RCT and the data for 139 of these were analysed. Participants were randomised to a control group with standard postoperative care or to an intervention group with care influenced (but not mandated) by the SAS (decisive approach). The notional primary outcome was 30-day major complications or death.

RESULTS

Incidence of major complications was similar in both groups (control: 20/69 [29%], intervention: 23/70 [33%], p=0.622). Immediate admissions to the critical care unit was higher in the intervention group, especially in the SAS 0-4 subgroup (4/6 vs 2/7) although this was not statistically significant (p=0.310). Validity was also confirmed in area under the curve (AUC) analysis (AUC: 0.77).

CONCLUSIONS

This pilot study found that a future RCT to investigate the effect of using the SAS in a decisive approach may demonstrate a difference in postoperative care. However, significant changes to the design are needed if differences in clinical outcome are to be achieved reliably. These would include a wider array of postoperative interventions implemented using a quality improvement approach in a stepped wedge cluster design with blinded collection of outcome data.

Sexual dysfunction in women with obstructive sleep apnea

BACKGROUND

Female sexual dysfunction is vastly under-recognized but has been previously described in chronic disease states. Sexual dysfunction in male patients with obstructive sleep apnea (OSA) is well described, but not in females.

OBJECTIVE

The objective of this study was to assess the prevalence of sexual dysfunction in women with OSA.

METHODS

We studied 21 consecutive pre-menopausal women with OSA, referred to our sleep lab, and who had a positive study for sleep apnea (respiratory disturbance index (RDI) > 5), and 11 healthy pre-menopausal women were included as the control group. Subjects were administered the Female Sexual Function Index (FSFI) questionnaire and a mood scale-Profile of Mood States.

RESULTS

Of the study group, 11 women (52.4%) had FSFI scores in the poor range (<23) as compared to the control group, in which none of the women (0%) had FSFI scores in the poor range (<23). Negative mood domain scores were not different in patients with poor FSFI compared to patients with normal FSFI scores. There was no correlation between obesity, severity of sleep apnea, or mood disorders on overall scores of sexual dysfunction. Among individual domains, there was a correlation between RDI and arousal scores.

CONCLUSION

In our study, we have found that prevalence of sexual dysfunction is high among women with OSA. Physicians should routinely screen and evaluate women with OSA for sexual dysfunction.

Stimulation of melanogenesis by tetradecanoylphorbol 13-acetate (TPA) in mouse melanocytes and neural crest cells

In vitro studies have shown that the phorbol ester, 12-tetradecanoylphorbol 13-acetate (TPA) induces neural crest cell differentiation into melanocytes, and stimulates proliferation and differentiation of normal melanocytes. As TPA is not a physiological agent, its action is clearly mimicking some in vivo pathway involved in these processes. An understanding of the effect of TPA on the expression of melanogenic genes will therefore provide valuable insight into the molecular mechanisms regulating melanocyte differentiation. In this study, we utilized primary cultures of neural crest cells and an immortalized melanocyte cell line (DMEL-2) which proliferates in the absence of TPA, to explore the effects of TPA on key melanogenic effectors. In neural crest cells, TPA was found to be necessary for both microphthalmia associated transcription factor (Mitf) up-regulation and for melanin synthesis. Using northern blots, we show that in DMEL-2 cells, TPA significantly increases the messenger ribonucleic acid (mRNA) levels of the tyrosinase gene family (tyrosinase, Tyrp1 and Dct) and the expression of Mitf. Western blots demonstrate that in these TPA-treated cells there is a concomitant increase in Tyr, Tyrp1 and glycosylated Dct protein levels. Pax3, a known Mitf regulator, is unaltered by TPA treatment. This study demonstrates the utility of a novel cell line for investigating the long-term effects of TPA on melanogenesis and provides an understanding of how TPA enhances mouse melanocyte differentiation.

Increased noradrenergic activity in prefrontal cortex slices of an animal model for attention-deficit hyperactivity disorder--the spontaneously hypertensive rat

Spontaneously hypertensive rats (SHR) are used as a model for attention-deficit/hyperactivity disorder (ADHD) since SHR are hyperactive and they show defective sustained attention in behavioral tasks. Using an in vitro superfusion technique we showed that norepinephrine (NE) release from prefrontal cortex slices of SHR was not different from that of their Wistar-Kyoto (WKY) control rats when stimulated either electrically or by exposure to buffer containing 25 mM K(+). The monoamine vesicle transporter is, therefore, unlikely to be responsible for the deficiency in DA observed in SHR, since, in contrast to DA, vesicle stores of NE do not appear to be depleted in SHR. In addition, alpha(2)-adrenoceptor mediated inhibition of NE release was reduced in SHR, suggesting that autoreceptor function was deficient in prefrontal cortex of SHR. So, while DA neurotransmission appears to be down-regulated in SHR, the NE system appears to be under less inhibitory control than in WKY suggesting hypodopaminergic and hypernoradrenergic activity in prefrontal cortex of SHR. These findings are consistent with the hypothesis that the behavioral disturbances of ADHD are the result of an imbalance between NE and DA systems in the prefrontal cortex, with inhibitory DA activity being decreased and NE activity increased relative to controls.

A clinical outcome and cost analysis of laparoscopic versus open appendectomy

BACKGROUND

Benefits of laparoscopic appendectomy are controversial, and the results of recent clinical studies have contradictory conclusions. We performed a cost analysis comparing laparoscopic and open appendectomies to assess potential efficacy of the laparoscopic approach.

METHODS

All patients operated on for suspected acute appendicitis at the University of Washington Medical Center (UWMC) from January 1, 1991 through January 1, 1995 were analyzed. Potential benefits of the laparoscopic approach were examined in five major categories: hospital length of stay, total hospital charges, operative time, operating room charges, and postoperative complications. Patients were stratified according to the presence or absence of perforation for outcome analysis.

RESULTS

There were 163 appendectomies performed in 82 men and 81 women. Twenty-seven (17%) patients had laparoscopic evaluation, of which 21 underwent attempted laparoscopic appendectomy. Among nonperforated patients, laparoscopic appendectomy did not reduce hospital stay compared with open appendectomy, but did lead to greater hospital charges ($7760 vs $5064; P < 0.001). Operating times were longer in the laparoscopic group (104 vs 74 minutes; P < 0.001) compared with open appendectomies. Operating room charges for laparoscopic appendectomies exceeded charges for the open approach ($4740 vs $1870; P < 0.001). Complication rates were similar (laparoscopic, 19% vs open, 16%; NS). The false diagnostic rate for women was four times greater than for men among patients undergoing open appendectomy (31% vs 8%; P < 0.01). Patients with perforation undergoing a midline incision had a longer hospital stay (9.5 vs 5.9; P < 0.02) than patients operated on through a right lower quadrant incision.

CONCLUSIONS

In our analysis, laparoscopic appendectomy, while safe, was more expensive and was not associated with better clinical outcome compared with open appendectomy patients.

Effect of multiple-dose activated charcoal on the clearance of high-dose intravenous aspirin in a porcine model

STUDY OBJECTIVE

To study the effect of multiple-dose activated charcoal (MDAC) on salicylate clearance in pigs given high-dose i.v. aspirin.

DESIGN

In a crossover design, six fasted pigs received 300 mg/kg i.v. aspirin followed by no treatment or MDAC (1 g/kg hourly for 6 doses by gastrostomy). Serum salicylate samples were obtained every 30 minutes for 6 hours.

RESULTS

The mean peak salicylate concentrations were 47.4 +/- 6.2 mg/dL and 48.4 +/- 3.9 mg/dL (P = .74), and the areas under the time-serum salicylate concentration curve over 6 hours were 171,000 +/- 24,000 mg.minute/L and 188,000 +/- 18,000 mg.minute/L for the control and treatment arms, respectively (P = .22). This study had a 90% power to detect a 30% difference between arms.

CONCLUSION

MDAC does not enhance the clearance of salicylate after administration of high-dose i.v. aspirin.

Value of a second freeze-thaw cycle in cryotherapy of common warts

A study of open, randomized, parallel-group design was performed to investigate the impact of a second freeze-thaw cycle on the cure rate, at 3 months, from cryotherapy of common warts on the hands and feet. Cryotherapy was performed at 3-week intervals, and subjects were randomized to receive either one or two freeze-thaw cycles. In addition, all subjects used keratolytic wart paints throughout the study, and plantar warts were pared prior to freezing. Three hundred subjects were recruited. At 3 months, 124 were cured, 83 were not cured, and 93 had defaulted. Among those who did not default the cure rate was 57% from the single freeze technique, and 62% from the double freeze technique, a difference of 5% (P = 0.53, 95% CI-8.1-18.6). Separate analyses for subjects with warts on the hands and on the feet demonstrated no effect of double freezing on hand warts. In contrast, for plantar warts, the cure rate was 41% from single freezing and 65% for double freezing, a difference of 24% (P = 0.04, 95% CI 2.9-44.4). The use of a double freeze-thaw cycle confers little or no advantage over a single freeze in the treatment of hand warts, but may be considerably more effective for plantar warts.

Superior fatigue resistance of elite black South African distance runners

Black athletes currently dominate long-distance running events in South Africa. In an attempt to explain an apparently superior running ability of black South African athletes at distances > 3 km, we compared physiological measurements in the fastest 9 white and 11 black South African middle-to long-distance runners. Whereas both groups ran at a similar percentage of maximal O2 uptake (%VO2max) over 1.65-5 km, the %VO2max sustained by black athletes was greater than that of white athletes at distances > 5 km (P < 0.001). Although both groups had similar training volumes, black athletes reported that they completed more exercise at > 80% VO2max (36 +/- 18 vs. 14 +/- 7%: P < 0.005). When corrections were made for the black athletes' smaller body mass, their superior ability to sustain a high %VO2max could not be explained by any differences in VO2max, maximal ventilation, or submaximal running economy. Superior distance running performance of the black athletes was not due to a greater (+/- 50%) percentage of type I fibers but was associated with lower blood lactate concentrations during exercise. Time to fatigue during repetitive isometric muscle contractions was also longer in black runners (169 +/- 65 vs. 97 +/- 69 s; P < 0.05), but whether this observation explains the superior endurance or was due to the lower peak muscle strength (46.3 +/- 10.3 vs. 67.5 +/- 18.0 Nm/l lean thigh volume; P < 0.01) remains to be established.

Skeletal muscle limits the exercise tolerance of renal transplant recipients: effects of a graded exercise training program

Sixteen renal transplant recipients were studied before and after they had participated in a 24-week exercise training program to determine (1) the nature of the factors explaining their impaired exercise tolerance, and (2) their adaptative responses to exercise training. During progressive treadmill exercise to exhaustion prior to training, renal transplant recipients stopped exercising at lower peak rates of oxygen consumption (VO2max) (29.0 +/- 7.8 47.9 +/- 9.1 mL O2.kg-1.min-1; P less than 0.001) and ventilation (55.9 +/- 13.2 v 124.0 +/- 22.2 L.min-1; P less than 0.0001), and at lower peak heart rates (169 +/- 22 v 196 +/- 9 beats.min-1; P less than 0.05) and peak blood lactate concentrations (5.0 +/- 2.1 v 11.5 +/- 4.0 mmol.L-1; P less than 0.001) than did controls. None showed a plateau in oxygen consumption with increasing workload. Exercise time to exhaustion was also significantly shorter in renal transplant recipients (9.5 +/- 1.8 v 16.0 +/- 1.3 min; P less than 0.0001). After training, exercise time to exhaustion (12.0 +/- 2.0 min; P less than 0.001), VO2max (37.5 +/- 4.8 mL O2.kg-1.min-1; P less than 0.05), maximum ventilation rate (68.5 +/- 14.0 L.min-1; P less than 0.05), peak blood lactate concentrations (7.8 +/- 1.8 mmol-L-1; P less than 0.001), and the rate of oxygen consumption at a blood lactate concentration of 2.0 mmol.L-1 (22.5 +/- 2.5 v 16.5 +/- 2.2 mL O2.kg-1.min-1; P less than 0.001) had all increased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Video endoscopy by nurse practitioners: a model for colorectal cancer screening

The use of paramedical personnel to perform sigmoidoscopy as a screening test for colorectal cancer has been advocated as a means of increasing the availability of this test to the population at risk. A model system has been developed utilizing flexible videosigmoidoscopy performed by nurse practitioners with videotape review by physician endoscopists. Of the 100 patients studied, 36 were found to have polyps. Near excellent concordance (k = 0.72) was observed between the nurse practitioner's findings and those of the physician. Using the physician's review as the standard, overall sensitivity and specificity of the nurse practitioner's examinations were 75% and 94%, respectively. In conclusion, videosigmoidoscopy performed by nurse practitioners and reviewed by physician endoscopists is a feasible approach to colorectal cancer screening since it is safe, provides videotape documentation to ensure quality control, and expands available resources for the performance of this examination.