Overview of ventilatory control during exercise.

Practically every respiratory physiologist of the last 100 years has studied the ventilatory response to exercise. Yet we still do not know the cause of increased ventilation associated with exercise. This overview considers the problem from a broad observational point of view. Data from studies combining exercise with continuous inspired CO2 and "slug" CO2 breathing imply a feed-forward/feed-back structure for the ventilatory controller. The feed-forward stimulus is correlated to CO2 production. Feed-back senses arterial CO2 tension and acts to minimize the effects of correlation errors and correlation slope errors in the feed-forward path. This feed-forward/feed-back structure yields a regulated arterial CO2 and a tight coupling of ventilation to CO2 production. The feed-back mechanism acts via the carotid body, and indirectly via the central chemoreceptor. A variety of mechanisms are discussed that may be involved in providing the feed-forward stimulus. In particular, the intravenous loading experimental results are considered in terms of an appropriate feed-forward stimulus.     

Pediatric evaluation of the bispectral index (BIS) monitor and correlation of BIS with end-tidal sevoflurane concentration in infants and children

The bispectral index (BIS) has been developed in adults and correlates well with clinical hypnotic effects of anesthetics. We investigated whether BIS reflects clinical markers of hypnosis and demonstrates agent dose-responsiveness in infants and children. In an observational arm of this study, BIS values in children undergoing general anesthesia were observed and compared with similar data collected previously in a study of adults. In a second arm of the study, a range of steady-state end-tidal concentrations of sevoflurane was administered and corresponding BIS documented. Data were examined for differences between infants (0-2 yr) and children (2-12 yr). No difference was seen in BIS values in children before induction, during maintenance, and on emergence compared with adult values. There was no difference in BIS between infants and children at similar clinical levels of anesthesia. In children and infants, BIS was inversely proportional to the end-tidal concentration of sevoflurane. The sevoflurane concentration for a BIS = 50 (95% confidence interval) was significantly different: 1. 55% (1.40-1.70) for infants versus 1.25% (1.12-1.37) for children. Although validation with specific behavioral end points was not possible, BIS correlated with clinical indicators of anesthesia in children as it did in adults: as depth of anesthesia increased, BIS diminished. BIS correlated with sevoflurane concentration in infants and children. The concentration-response difference between infants and children was consistent with data showing that minimum alveolar concentration is higher in children less than 1 yr of age. IMPLICATIONS: The use of bispectral index (BIS) during general anesthesia improves the titration of anesthetics in adults. The data from this study suggest that the same equipment and method of electroencephalogram analysis may be applied to infants and children.     

Surveillance transbronchial lung biopsies: implication for survival after lung transplantation

OBJECTIVES: We wished to determine whether early rejection after lung transplantation as assessed by surveillance transbronchial biopsy predicts for survival. METHODS: Between 1990 and 1997, 96 consecutive patients had lung transplantation: 89 had a minimum 1-month follow-up. For 71 consecutive patients we have 1-year follow-up and for 69 patients we have the results of the first 3 biopsies. Cytomegalovirus status, bronchiolitis obliterans prevalence, and use of total lymphoid irradiation are noted. Biopsies were done at 1 week and 1, 3, and 6 months. Standard immunosuppression consisted of induction antilymphocyte globulin and high-dose methylprednisolone induction for 1 week and standard maintenance triple therapy. Acute rejection treatment was with pulse methylprednisolone. Bronchiolitis obliterans syndrome was treated with total lymphoid irradiation and a change to tacrolimus and mycophenolate. Blinded grading using International Society for Heart and Lung Transplantation classification was done retrospectively. RESULTS: Survival at 1 month and 1, 2, and 3 years for the 96-patient cohort with 1-year follow-up was 93%, 74%, 62%, and 56%. Survival was not significantly different for subsets with rejection on any combination of the first 3 biopsies (1/3, 2/3, 3/3) or absence of rejection on the first 3 biopsies. Ninety-one positive biopsy results were graded. Eighteen of 71 patients had one or more moderate or severe rejection episodes without survival difference relative to the others. There was no statistically significant association between acute rejection on the first 3 surveillance biopsy results and bronchiolitis obliterans. CONCLUSIONS: Intensive induction and maintenance immunotherapy with surveillance transbronchial biopsies and aggressive treatment of acute rejection is associated with a survival similar to that of patients without early acute rejection. This regimen appears to uncouple the association between early acute rejection and bronchiolitis obliterans. Further study may elucidate this mechanism.     

Experience with endoluminal colonic wall stents for the management of large bowel obstruction for benign and malignant disease

HYPOTHESIS: To assess the applicability and efficacy of endoluminal colonic wall stents (ECWSs) in the management of large bowel obstruction (LBO). DESIGN: Inception cohort study. SETTING: University-based tertiary medical center. PATIENTS: Eleven consecutive patients with LBO in the absence of peritonitis. INTERVENTION: Placement of ECWS under endoscopic and fluoroscopic guidance. MAIN OUTCOME MEASURES: The success rate in ECWS placement, the efficacy in decompressing the obstruction, and the patency rate of the ECWS. RESULTS: Successful placement of ECWSs was obtainable in 10 of 11 patients. Once placed, all 10 patients achieved immediate decompression of their LBO. Eight patients had malignant obstructions associated with distant spread of disease; 3 patients had diverticular disease. Among those with malignant obstruction, 6 patients had successful and lasting palliation without colostomy, 1 patient underwent 1-stage resection 1 month later with no evidence of obstruction, and 1 patient could not be stented so diversion was done. None of the patients with diverticular disease required diversion: 2 had complete bowel preparation followed by resection with primary anastomosis, whereas the third declined surgery. Four of the 10 patients required overlapping ECWSs to bridge the stricture. One patient required a second ECWS secondary to recurrence of obstruction after stent migration and has continued palliation of his stage 4 rectal cancer for the last 11 months. No other complications were encountered. CONCLUSIONS: Urgent surgery with colostomy for LBO was avoided in 10 of 11 patients because of successful placement of ECWSs. We believe that endoscopic colonic stenting is safe, effective, and lasting, and should be considered as initial nonoperative management in all patients seen with LBO in the absence of peritonitis.     

Surgery and Staging of Pancreatic Neuroendocrine Tumors: A 14-Year Experience

Background  

The aims of this study were to evaluate contemporary outcomes associated with the surgical management of pancreatic neuroendocrine tumors (PNETs) and to assess the prognostic value of the World Health Organization (WHO) classification and TNM staging for PNETs.     

Caucasian and Mexican American low‐income children's thoughts about vegetables and fruits

The objective of this study was to determine behavioral, personal, and environmental factors that influence low‐income children's fruit and vegetable intake. Focus group questions were developed using the social cognitive theory (SCT). Four Caucasian (27 children) and six Mexican American focus groups (30 children) were conducted. Mexican‐American children stated they had the ability to prepare vegetables and fruits whereas Caucasian children expressed they would rather have their parents do the preparation. This is an example of the behavioral capability construct of SCT. Both ethnic groups mentioned they did not know where vegetables and fruits were stored in the home and this is an environmental construct of SCT. Personal factors of the SCT included Caucasian children preferring to add peanut butter and Ranch dip to vegetables compared to Mexican‐American children preferring to add salt, lime, and chili to vegetables. Sweetness, sourness, juiciness, and crunchiness were seen as good characteristics. All focus groups perceived vegetables and fruits as healthy. All of these issues need to be considered when developing nutrition programming for children.     

Surviving child abuse: Self‐reported coping histories of fourteen women

Data are presented about coping methods used by 14 women who survived severe physical child abuse. Half of these women were also sexually abused as children. Self‐reports revealed four belief systems among these women as to how they survived this abuse. Three women believe they coped predominantly by helping people in their milieu who were even more disadvantaged. Three describe themselves as having survived mostly by learning to forget real feelings through use of intense fantasy. Five feel they survived by becoming tough and independent and by keeping moving through jobs and relationships. Three believe they coped by being realistic and working hard. Seven case histories are provided, along with illustrative material on the other seven subjects.