Biomedical subjects

Linda L Liu

Publications and source records attributed to Linda L Liu.

5 recordsLinked to original sources

PubMed2005

Aging and the neural correlates of successful picture encoding: frontal activations compensate for decreased medial-temporal activity.

We investigated the hypothesis that increased prefrontal activations in older adults are compensatory for decreases in medial-temporal activations that occur with age. Because scene encoding engages both hippocampal and prefrontal sites, we examined incidental encoding of scenes by 14 young and 13 older adults in a subsequent memory paradigm using functional magnetic resonance imaging (fMRI). Behavioral results indicated that there were equivalent numbers of remembered and forgotten items, which did not vary as a function of age. In an fMRI analysis subtracting forgotten items from remembered items, younger and older adults both activated inferior frontal and lateral occipital regions bilaterally; however, older adults showed less activation than young adults in the left and right parahippocampus and more activation than young adults in the middle frontal cortex. Moreover, correlations between inferior frontal and parahippocampal activity were significantly negative for old but not young, suggesting that those older adults who showed the least engagement of the parahippocampus activated inferior frontal areas the most. Because the analyses included only the unique activations associated with remembered items, these data suggest that prefrontal regions could serve a compensatory role for declines in medial-temporal activations with age.

Adult↗

PubMed2004

Aging and medical adherence: the use of automatic processes to achieve effortful things.

This research examined whether forming detailed implementation plans for achieving a goal improved older adults' adherence to a health behavior. Nondiabetic participants (N = 31) rehearsed, deliberated, or formed implementation intentions to perform home blood glucose monitoring, 4 times daily for 3 weeks. The implementation group performed tests nearly 50% more often than the 2 comparison groups. Results were not attributable to a priori differences in intentions to perform testing. Findings indicate that implementation intentions can facilitate older adults' performance of important medical self-care tasks in naturalistic settings over sustained periods of time and concur with previous research that implicates automatic cognitive processes that do not show age-related decline. These results support the utility of this technique for improving adherence to health behaviors in clinical populations.

Aged↗

PubMed2003

Perioperative anesthesia issues in the elderly.

Surgical procedures on geriatric patients are not always benign, but postoperative mortality and morbidity is improving. Optimal care depends on our ability to recognize potential risk factors and intervene in a positive manner. Not all the data are complete, and we are missing several key randomized trials, but investigators have identified many areas for possible intervention. Hopefully, in the near future, more concrete recommendations can be given for this very large and important topic of perioperative anesthetic issues in the elderly.

Adrenergic beta-Antagonists↗

PubMed2003

Postoperative analgesia and sedation in the adult intensive care unit: a guide to drug selection.

An essential goal of all critical care physicians should be to maintain an optimal level of pain control and sedation for their patients. This has become increasingly important because of evidence showing that the combined use of sedatives and analgesics may ameliorate the detrimental stress response in critically ill patients. Unfortunately, both pain and anxiety are subjective and difficult to measure, thereby limiting our ability to analyse these states and making management more challenging. Although there is still a lack of high quality, randomised, prospective, controlled trials comparing agents, monitoring techniques and scoring scales, several societies have come together to publish some clinical practice guidelines for sedation and analgesia. Recommended opioids are fentanyl or hydromorphone for short-term use, and morphine or hydromorphone for longer-term therapy. Midazolam or diazepam are recommended for sedation of the acutely agitated patient, while lorazepam is recommended for longer infusions. Propofol is preferred when rapid awakening is desired. The challenge for critical care physicians is to use these medications to provide comfort and safety without increasing morbidity or mortality. Most studies support the use of protocols in order to help achieve these goals. The bottom line is that most protocols end up stressing some common issues. These include daily cessation of drugs to evaluate the patient and frequent reassessment of the level of sedation required by each specific patient. Much is still unknown about the long-term effects of sedative and analgesic drugs used as infusions that may last from days to weeks to months. Hopefully, as more studies are performed, we will have more defined clinical end-points, newer drugs with rapid onset and offset and no active metabolites, and decreased morbidity and mortality for our patients.

Adult↗

PubMed2002

Preoperative electrocardiogram abnormalities do not predict postoperative cardiac complications in geriatric surgical patients.

OBJECTIVES: Preoperative electrocardiograms (ECGs) are routinely performed on older patients before surgery. Whether patients with abnormalities on preoperative ECGs have an increased likelihood of developing postoperative cardiac complications is unknown. This study was designed to determine whether abnormalities on preoperative ECGs were predictive of postoperative cardiac complications. DESIGN: Prospective observational study. SETTING: One of the teaching hospitals of the University of California, San Francisco, Medical Center. PARTICIPANTS: Five hundred thirteen patients aged 70 and older undergoing noncardiac surgery. MEASUREMENTS: Preoperative ECGs were analyzed using the Minnesota Codes. Predefined preoperative risk factors and in-hospital postoperative cardiac complications were measured. The association between ECG abnormalities and postoperative cardiac complications was determined by multivariate logistic regression after controlling for clinical covariates. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported. RESULTS: Three hundred eighty-six of 513 patients (75.2%) had at least one abnormality on their preoperative ECGs. On multivariate analysis, the predictors of postoperative cardiac complications included American Society of Anesthesiologists physical status classification of 3 or greater (OR = 2.5, 95%CI = 1.28-4.89, P = .007) and a history of congestive heart failure (OR = 2.1, 95% CI = 1.1-5.1, P = .034). The presence of abnormalities on preoperative ECGs was not associated with an increased risk of postoperative cardiac complications (OR = 0.63, 95% CI = 0.28-1.40, P = .26). CONCLUSION: Abnormalities on preoperative ECGs are common but are of limited value in predicting postoperative cardiac complications in older patients undergoing noncardiac surgery. These results suggest that obtaining preoperative ECGs based on an age cutoff alone may not be indicated, because ECG abnormalities in older people are prevalent but nonspecific and less useful than the presence and severity of comorbidities in predicting postoperative cardiac complications.

Aged↗