Search PubMed⌕ Search

Biomedical subjects

M Knudson

Publications and source records attributed to M Knudson.

5 recordsLinked to original sources
PubMed1988

Intussusception. A case that suggests a new cardinal symptom--lethargy.

Intussusception is an uncommon condition, but it is the most frequent cause of bowel obstruction in infants and children aged 3 months to 5 years. If undiagnosed, it can result in bowel necrosis, perforation, and even death. Four cardinal signs and symptoms (abdominal pain, rectal bleeding, vomiting, and abdominal mass) are described in patients with intussusception, but these manifestations are not always present and their absence may lead to misdiagnosis. Lethargy might be considered a fifth cardinal symptom. As demonstrated in this case, lethargy may be a significant presenting feature in an infant with no history of abdominal pain, and in association with the other cardinal symptoms, it may be an early indication of a significant illness such as intussusception. Awareness of this association may result in an earlier diagnosis and an improved outcome in patients with intussusception.

Female↗
PubMed1988

Evaluation of an educational intervention to increase health promotion by residents.

Preventive health practices known to benefit the general public include aerobic exercise, seat belt use, and self-examination for breast or testicular cancer. Unfortunately, none of these practices is universally promoted by physicians, nor are they widely practiced by patients. To assess whether residents who received a packet of printed material on these four health-related practices and had a 5- to 15-minute review of the material with a physician and an educator would increase their promotion of these healthful behaviors, a controlled trial was conducted at the University of Missouri--Columbia Hospitals and Clinics. When baseline differences in the behavior between the intervention and control groups of residents were controlled statistically, there was no significant difference in the amount of health promotion done by the two groups after the educational intervention. An educational intervention may not be an effective way to increase residents' promotion of healthful activities. These results raise questions about the methods used in some previously published studies that suggested favorable effects of education on physicians' behavior.

Family Practice↗
PubMed1983

Physiologic benefits of rate responsiveness.

Increases in metabolic demand in response to routine activities and exercise are met through greater cardiac output and oxygen delivery. Patients with fixed-rate pacemakers cannot increase heart rate and must rely solely on increases in stroke volume to provide the necessary adjustments in cardiac output. These compensatory stroke volume increases limit the fixed-rate pacemaker patient's ability to meet the demand of their daily routine. A physiological, rate responsive pacemaker was studied and it was found to increase maximum exercise tolerance from 4.4 +/- .62 METS paced VVI at 65 ppm to 8.1 +/- .71 METS when the same patients were paced rate responsively at an average rate of 91 +/- 3.8 ppm. Animal studies were used to quantify the limitation in stroke volume reserve. Maximum increases of 55.8 +/- 3.7% over resting values were seen in animals in complete heart block at pacing rates of 100 ppm during strenuous exercise. Higher pacing rates increased cardiac output at the same exercise intensity, from 4.94 +/- .72 lpm at 100 ppm to 7.66 +/- 1.02 lpm at 250 ppm. A pacemaker that increases pacing rate in response to greater metabolic demand will maintain stroke volume and end-diastolic volume at near normal values while providing significant improvement in cardiac output and work capacity.

Animals↗
PubMed1983

Orthogonal electrogram sensing.

Intracardiac electrogram sensing is the afferent limb of demand pacing systems. Under- and over-sensing at the ventricular level has been demonstrated in almost 50% of implanted unipolar pulse generators, and atrial electrogram sensing problems are more common. A unique dedicated sensor employing noncontacting and circumferentially placed orthogonal electrodes was tested at both the atrial and ventricular levels. Electrograms demonstrated voltages similar to those recorded from contacting electrodes, but with complete far-field rejection of signals from the opposite chamber. Orthogonal electrograms allowed for activation sequencing and capture verification as well.

Electric Conductivity↗