Intraoperative ventilation: incidence and risk factors for receiving large tidal volumes during general anesthesia.

BACKGROUND: There is a growing concern of the potential injurious role of ventilatory over-distention in patients without lung injury. No formal guidelines exist for intraoperative ventilation settings, but the use of tidal volumes (VT) under 10 mL/kg predicted body weight (PBW) has been recommended in healthy patients. We explored the incidence and risk factors for receiving large tidal volumes (VT > 10 mL/kg PBW). METHODS: We performed a cross-sectional analysis of our prospectively collected perioperative electronic database for current intraoperative ventilation practices and risk factors for receiving large tidal volumes (VT > 10 mL/kg PBW). We included all adults undergoing prolonged (≥ 4 h) elective abdominal surgery and collected demographic, preoperative (comorbidities), intraoperative (i.e. ventilatory settings, fluid administration) and postoperative (outcomes) information. We compared patients receiving exhaled tidal volumes > 10 mL/kg PBW with those that received 8-10 or < 8 mL/kg PBW with univariate and logistic regression analyses. RESULTS: Ventilatory settings were non-uniform in the 429 adults included in the analysis. 17.5% of all patients received VT > 10 mL/kg PBW. 34.0% of all obese patients (body mass index, BMI, ≥ 30), 51% of all patients with a height < 165 cm, and 34.6% of all female patients received VT > 10 mL/kg PBW. CONCLUSIONS: Ventilation with VT > 10 mL/kg PBW is still common, although poor correlation with PBW suggests it may be unintentional. BMI ≥ 30, female gender and height < 165 cm may predispose to receive large tidal volumes during general anesthesia. Further awareness of patients' height and PBW is needed to improve intraoperative ventilation practices. The impact on clinical outcome needs confirmation.

Postoperative delirium in the elderly: risk factors and outcomes.

OBJECTIVE: The purpose of this study was to describe the natural history, identify risk factors, and determine outcomes for the development of postoperative delirium in the elderly. BACKGROUND: Postoperative delirium is a common and deleterious complication in geriatric patients. METHODS: Subjects older than 50 years scheduled for an operation requiring a postoperative intensive care unit admission were recruited. After preoperative informed written consent, enrolled subjects had baseline cognitive and functional assessments. Postoperatively, subjects were assessed daily for delirium using the confusion assessment method-intensive care unit. Patients were also followed for outcomes. RESULTS: During the study period, 144 patients were enrolled before major abdominal (40%), thoracic (53%), or vascular (7%) operations. The overall incidence of delirium was 44% (64/144). The average time to onset of delirium was 2.1 +/- 0.9 days and the mean duration of delirium was 4.0 +/- 5.1 days. Several preoperative variables were associated with an increased risk of delirium including older age (P < 0.001), hypoalbuminemia (P < 0.001), impaired functional status (P < 0.001), pre-existing dementia (P < 0.001), and pre-existing comorbidities (P < 0.001). In a multivariable logistic regression model, pre-existing dementia remains the strongest risk factor for the development of postoperative delirium. Worse outcomes, including increased length of stay (P < 0.001), postdischarge institutionalization (P < 0.001), and 6 month mortality (P = 0.001), occurred in subjects who developed delirium. CONCLUSIONS: In the current study, delirium occurred in 44% of elderly patients after a major operation. Pre-existing cognitive dysfunction was the strongest predictor of the development of postoperative delirium. Outcomes, including an increased rate of 6 month mortality, were worse in patients who developed postoperative delirium.

Metabolic profiles in urine reflect nephrotoxicity of sirolimus and cyclosporine following rat kidney transplantation.

BACKGROUND: Cyclosporine and/or sirolimus impair recovery of renal transplants. This study examines the changes in urine metabolite profiles as surrogate markers of renal cell metabolism and function after cyclosporine and/or sirolimus treatment employing a rat kidney transplantation model. METHODS: Using inbred Lewis rats, kidneys were transplanted into bilaterally nephrectomized recipients followed by treatment with either CsA (cyclosporine) 10, Rapa (sirolimus) 1, CsA10/Rapa1 or CsA25/Rapa1 mg/kg/day for 7 days. On day 7, urine was analyzed by (1)H-NMR spectroscopy. Blood and kidney tissue drug concentrations, tissue high-energy compounds (including ATP, ADP) and oxidative stress markers (15-F(2t)-isoprostanes) in urine were measured by HPLC mass spectrometry. RESULTS: Changes in urine metabolites followed the order Rapa1 < CsA10 < CsA10/Rapa1 < CsA25/Rapa1. Compared with controls, CsA25/Rapa1 showed the greatest changes (creatinine -36%, succinate -57%, citrate -89%, alpha-ketoglutarate -75%, creatine +498%, trimethylamine +210% and taurine +370%). 15-F(2t)-isoprostane concentrations in urine increased in the combined immunosuppressant-treated animals ([CsA25/Rapa1]: 795 +/- 222, [CsA10/Rapa1]: 475 +/- 233 pg/mg/creatinine) as compared with controls (165 +/- 78 pg/mg creatinine). Rapa concentration in blood and tissues increased in the combined treatment (blood: 31 +/- 8 ng/ml, tissue: 1.3 +/- 0.4 ng/mg) as compared with monotherapy (blood: 14 +/- 8 ng/ml, tissue: 0.35 +/- 0.15 ng/mg). Drug blood concentrations correlated with isoprostane urine concentrations, which correlated negatively with citrate, alpha-ketoglutarate and creatinine concentrations in urine. Only CsA25/Rapa1 significantly reduced high-energy metabolite concentrations in transplant kidney tissue (ATP -55%, ADP -24%). CONCLUSION: Immunosuppressant drugs induce changes in urine metabolite patterns, suggesting that immunosuppressant-induced oxidative stress is an early event in the development of nephrotoxicity. Urine 15-F(2t)-isoprostane concentrations and metabolite profiles may be sensitive markers of immunosuppressant-induced nephrotoxicity.

Controlled endurance exercise training and VO2max changes in older adults: a meta-analysis.

This meta-analysis of controlled clinical trials quantifies the effect of aerobic exercise on VO2max (aerobic fitness) among sedentary older adults and examines the associations of such magnitude with variables of intervention. Forty-one trials including 2102 older subjects (within-group mean age of 60 years and older) were identified by searches of databases, hand searching, and cross-referencing. Outcomes were homogeneous. The pooled standardized effect size by a fixed-effect model showed a higher moderate effect (mean +/- SEM) of 0.64+/-0.05; 95% confidence interval, 0.56-0.73; p<0.001, representing a net increase in VO2max (mean +/- SEM) of 3.78+/-0.28 mL.kg-1.min-1; 95% confidence interval, 3.24-4.33; or a 16.3% improvement, compared with control groups. Greater improvement in VO2max was associated with training length more than 20 weeks and training intensity of approximately 60% but less than 70% of VO2max. Endurance training improves aerobic fitness in older adults, thus providing protective benefits for cardiovascular aging and quality of later life.

Exercise, lipids, and lipoproteins in older adults: a meta-analysis.

The authors used the meta-analytic approach to examine the effects of aerobic exercise on lipids and lipoproteins in adults 50 years of age and older. Twenty-eight outcomes representing 1427 subjects (806 exercise, 621 control) were available for pooling. Random-effects modeling yielded statistically significant improvements of 1.1%, 5.6%, 2.5%, and 7.1%, respectively, for total cholesterol (mean +/- SEM in mg/dL, -3.3+/-1.7; 95% confidence interval [CI], -6.5 to -0.02; p=0.05), high-density lipoprotein cholesterol (2.5+/-1.0; 95% CI, 0.7-4.4; p=0.01), low-density lipoprotein cholesterol (-3.9+/-1.9; 95% CI, -7.7 to -0.08; p=0.05), ratio of total cholesterol to high-density lipoprotein cholesterol (-0.8+/-0.2; 95% CI, -1.2 to -0.4; p<0.001), but not triglycerides (-7.0+/-3.6; 95% CI, -14.0 to 0.1; p=0.06). After conducting sensitivity analyses, only the improvements in high-density lipoprotein cholesterol and the ratio of total cholesterol to high-density lipoprotein cholesterol remained statistically significant (p<0.05 for both). It was concluded that aerobic exercise increases high-density lipoprotein cholesterol and decreases the ratio of total cholesterol to high-density lipoprotein cholesterol in older adults.

Effects of a 16-month randomized controlled exercise trial on body weight and composition in young, overweight men and women: the Midwest Exercise Trial.

BACKGROUND: In light of the current obesity epidemic, treatment models are needed that can prevent weight gain or provide weight loss. We examined the long-term effects of a supervised program of moderate-intensity exercise on body weight and composition in previously sedentary, overweight and moderately obese men and women. We hypothesized that a 16-month program of verified exercise would prevent weight gain or provide weight loss in the exercise group compared with controls. METHODS: This was a randomized controlled efficacy trial. Participants were recruited from 2 midwestern universities and their surrounding communities. One hundred thirty-one participants were randomized to exercise or control groups, and 74 completed the intervention and all laboratory testing. Exercise was supervised, and the level of energy expenditure of exercise was measured. Controls remained sedentary. All participants maintained ad libitum diets. RESULTS: Exercise prevented weight gain in women and produced weight loss in men. Men in the exercise group had significant mean +/- SD decreases in weight (5.2 +/- 4.7 kg), body mass index (calculated as weight in kilograms divided by the square of height in meters) (1.6 +/- 1.4), and fat mass (4.9 +/- 4.4 kg) compared with controls. Women in the exercise group maintained baseline weight, body mass index, and fat mass, and controls showed significant mean +/- SD increases in body mass index (1.1 +/- 2.0), weight (2.9 +/- 5.5 kg), and fat mass (2.1 +/- 4.8 kg) at 16 months. No significant changes occurred in fat-free mass in either men or women; however, both had significantly reduced visceral fat. CONCLUSIONS: Moderate-intensity exercise sustained for 16 months is effective for weight management in young adults.

Tryptophan supplementation and postoperative delirium--a randomized controlled trial.

OBJECTIVES: To determine whether the postoperative administration of tryptophan would be beneficial for elderly adults undergoing surgery who are at risk of developing postoperative delirium. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Denver Veterans Affairs Medical Center. PARTICIPANTS: Individuals aged 60 and older undergoing major elective operations requiring a postoperative intensive care unit (ICU) admission (n = 325). INTERVENTION: L-tryptophan, 1 g orally three times a day or placebo was started after surgery and continued for up to 3 days postoperatively. MEASUREMENTS: Delirium and its motor subtypes were measured using the Confusion Assessment Method-Intensive Care Unit (CAM-ICU) and the Richmond Agitation and Sedation Scale. The primary outcome for between-group comparison was the incidence of excitatory (mixed and hyperactive) postoperative delirium. The secondary outcomes for comparison were the incidence and duration of overall postoperative delirium. RESULTS: The overall incidence of postoperative delirium was 39% (95% confidence interval = 34-44%) (n = 116). Seventeen percent of participants in the tryptophan group and 9% in the placebo group had excitatory delirium (P = .18), and the duration of excitatory delirium was 3.3 ± 1.7 days for tryptophan and 3.1 ± 1.9 days for placebo (P = .74). Forty percent of participants in the tryptophan group and 37% in the placebo group had overall delirium (P = .60), and the duration of overall delirium was 2.9 ± 1.8 days for tryptophan and 2.4 ± 1.6 days for placebo (P = .17). CONCLUSION: Postoperative tryptophan supplementation in older adults undergoing major elective operations requiring postoperative ICU admission did not reduce the incidence or duration of postoperative excitatory delirium or overall delirium.

Postoperative falls in the acute hospital setting: characteristics, risk factors, and outcomes in males.

BACKGROUND: Hospital falls are an important cause of morbidity in older surgical patients. The objectives of this study were to describe the characteristics, risk factors, and outcomes for postoperative falls. METHODS: A retrospective study was performed on patients who were admitted to the hospital for more than 23 hours after surgery. Patients who fell within 30 days of their surgery were considered to have experienced a postoperative fall. RESULTS: Over 5 years and 9,625 inpatient surgical procedures, 154 patients experienced 190 falls. Injuries resulting from postoperative falls included major injury (hip fracture), less than 1%; injury requiring intervention, 2%; injury not requiring intervention, 27%; and no injury, 70%. Variables associated with postoperative falls included older age, functional dependence, lower albumin level, and higher American Society of Anesthesia score. CONCLUSIONS: One or more postoperative falls occurred in 1.6% of surgical inpatients and can lead to significant morbidity. Recognition of fall risk factors will help design postoperative fall prevention programs by identifying patients at highest risk for postoperative falls.

Motor subtypes of postoperative delirium in older adults.

HYPOTHESIS: Increased knowledge about motor subtypes of delirium may aid clinicians in the management of postoperative geriatric patients. DESIGN: Prospective cohort study defining preoperative risk factors, outcomes, and adverse events related to motor subtypes of postoperative delirium. SETTING: Referral medical center. PATIENTS: Persons 50 years and older with planned postoperative intensive care unit (ICU) admission following an elective operation were recruited. MAIN OUTCOME MEASURES: Before surgery, a standardized frailty assessment was performed. After surgery, delirium and its motor subtypes were measured using the validated tools of the Confusion Assessment Method-ICU and the Richmond Agitation-Sedation Scale. Statistical analysis included the univariate t and χ(2) tests and analysis of variance with post hoc analysis. RESULTS: Delirium occurred in 43.0% (74 of 172) of patients, representing 67.6% (50 of 74) hypoactive, 31.1% (23 of 74) mixed, and 1.4% (1 of 74) hyperactive motor subtypes. Compared with those having mixed delirium, patients having hypoactive delirium were older (mean [SD] age, 71 [9] vs 65 [9] years) and more anemic (mean [SD] hematocrit, 36% [8%] vs 41% [6%]) (P = .002 for both). Patients with hypoactive delirium had higher 6-month mortality (32.0% [16 of 50] vs 8.7% [2 of 23], P = .04). Delirium-related adverse events occurred in 24.3% (18 of 74) of patients with delirium; inadvertent tube or line removals occurred more frequently in the mixed group (P = .006), and sacral skin breakdown was more common in the hypoactive group (P = .002). CONCLUSIONS: Motor subtypes of delirium alert clinicians to differing prognosis and adverse event profiles in postoperative geriatric patients. Hypoactive delirium is the most common motor subtype and is associated with worse prognosis (6-month mortality, 1 in 3 patients). Knowledge of differing adverse event profiles can modify clinicians' management of older patients with postoperative delirium.

Risk factors for delirium after major trauma.

BACKGROUND: This study aimed to describe the natural history of delirium after major injury, to identify risk factors that predict the development of postinjury delirium, and to compare outcome measures in subjects with and without delirium. METHODS: A prospective study was performed on patients with an injury severity score of 8 or higher admitted to the trauma intensive care unit (ICU) of a level I trauma center. Patients underwent daily assessments for delirium with the Confusion Assessment Method-ICU. RESULTS: Sixty-nine patients (53 male) were enrolled. Delirium occurred in 41 (59%) subjects. Logistic regression found lower arrival Glasgow Coma Score (12 +/- 1.0 vs 15 +/- .1; P < .01), increased blood transfusions (2.8 +/- .7 vs .5 +/- .3; P < .01), and higher multiple organ failure score (1.2 +/- .2 vs .1 +/- .1; P < .01) to be the strongest predictors for developing delirium. Outcome measures revealed subjects with delirium had longer hospital stays, longer ICU stays, and were more likely require postdischarge institutionalization. CONCLUSIONS: Delirium is common in the trauma ICU. Higher multiple organ failure score was the strongest predictor of postinjury delirium.

Using telehealth to increase participation in weight maintenance programs.

OBJECTIVE: To compare weight regain, satisfaction, and convenience among three weight maintenance programs: telehealth, traditional classes, and no program. RESEARCH METHODS AND PROCEDURES: This quasi-experimental study compared weight change, satisfaction, and convenience among three program types. The telehealth participants interacted with a registered dietitian (RD) through the web and e-mail, traditional program participants attended a traditional classroom program, and no program participants received no interaction. Eighty-seven subjects (14 men and 73 women) were enrolled in the study: 31 traditional, 31 telehealth, and 25 no program participants. Eligibility included participation in a community-based weight loss program (Colorado Weigh) and minimum 7% weight loss before enrollment. RESULTS: Subject characteristics at baseline were as follows: age, 50 +/- 9.3 (standard deviation) years; height, 1.68 +/- 0.09 m; weight, 80.5 +/- 18.4 kg, with no significant differences between groups. Over 6 months, the traditional group lost 0.5 +/- 4.3 kg, the telehealth group lost 0.6 +/- 2.5 kg, and the no program group gained 1.7 +/- 3.0 kg. Weight change among all three groups was significant (p = 0.02); no program participants gained significantly more weight than the telehealth and traditional groups. There were no differences in overall satisfaction between the telehealth and traditional groups (p = 0.43), but individuals in the telehealth group rated their program as more convenient compared with the traditional group (p = 0.0001). DISCUSSION: These results show the usefulness of telehealth programs in long-term weight loss maintenance. They may be a useful alternative for those who successfully lose weight in a structured behavioral program but do not choose to participate in a formal behavioral weight loss maintenance program.

A multicenter evaluation of safety of early extubation in liver transplant recipients.

Small single-institutional studies performed prior to the introduction of organ allocation using the Model for End-Stage Liver Disease (MELD) suggest that early airway extubation of liver transplant recipients is a safe practice. We designed a multicenter study to examine adverse events associated with early extubation in patients selected for liver transplantation using MELD score. A total of 7 institutions extubated all patients meeting study criteria and reported adverse events that occurred within 72 hours following surgery. Adverse events were uncommon: occurring in only 7.7% of 391 patients studied. Most adverse events were pulmonary or surgically related. Pulmonary complications were usually minor, requiring only an increase in ambient oxygen concentration. The majority of surgical adverse events required additional surgery. Analysis of a limited set of perioperative variables suggest that blood transfusions and technical factors were associated with an increased risk of adverse events. In conclusion, while early extubation appears to be safe under specified circumstances, there are performance differences between institutions that remain to be explained.