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Biomedical subjects

K Davis

Publications and source records attributed to K Davis.

At least 235 records · Page 13Linked to original sources
PubMed1992

To smile again.

Explore the source record for details and available documents.

Adaptation, Psychological↗
PubMed1992

Monoethylglycinexylidide production parallels changes in hepatic blood flow and oxygen delivery in lung injury managed with positive end-expiratory pressure.

Mechanical ventilation with high levels of positive end-expiratory pressure (PEEP) decreases hepatic blood flow (HBF) and hepatic oxygen delivery (HO2D). Noninvasive methods of detecting decreased HBF might prevent hepatic ischemia and dysfunction. Monoethylglycinexylidide (MEGX) is a hepatic metabolite of lidocaine, used clinically to determine graft function following hepatic transplantation. In order to test the hypothesis that MEGX production would be affected by changes in hepatic hemodynamics associated with lung injury, 12 dogs were instrumented with femoral and pulmonary artery catheters. Splenectomy was performed and the portal and hepatic veins cannulated. The hepatic artery and portal vein were encircled with flow probes. Lung injury was induced in six animals (INJURED group) with oleic acid (0.08 mL/kg) and 10 cm H2O PEEP was added to correct subsequent shunt. Levels of MEGX were measured 15 minutes after injection of intravenous lidocaine (1 mg/kg). Levels of HBF, HO2D, and MEGX were measured at BASELINE, after lung injury (INJURY time point), and after addition of PEEP (PEEP time point). CONTROL animals (n = 6) were studied at the same time points but without lung injury or PEEP. Hepatic blood flow and hepatic oxygen delivery were significantly decreased after lung injury and further decreased after PEEP. Levels of MEGX were unchanged in the CONTROL group but were significantly reduced by lung injury and PEEP in the INJURED group. Decreased MEGX production may be a useful clinical indicator of reduced hepatic flow and oxygen supply in critical illness.

Animals↗
PubMed1992

Cost and complications during in-hospital transport of critically ill patients: a prospective cohort study.

We prospectively studied transport of a group of 100 surgery/trauma patients and a matched control group in the ICU. APACHE II scores for the two groups were 23 +/- 6 and 20 +/- 8. During transport both groups had ECG, heart rate, blood pressure, and oxygen saturation continuously monitored. We also determined the cost and results of transport for those patients requiring diagnostic testing. There were six diagnostic tests performed: CT scan of the abdomen (39%), CT scan of the head (31%), CT scan of the chest (8%), CT scan of the cervical spine (4%), angiography (14%), and tomography (4%). Average transport time was 74 +/- 16 minutes with a range of 20-225 minutes. Physiologic changes defined as a BP +/- 20 mm Hg, heart rate +/- 20 beats/min, respiratory rate +/- 5 breaths/min, or oxygen saturation +/- 5% for 5 minutes duration occurred in 66% of transported patients and 60% of ICU patients. There were no differences in arterial blood gas levels before and during transport. In 39% of transports, the results of diagnostic testing produced a change in patient management within 48 hours. Abdominal CT scanning and angiography were associated with the highest percentage of tests leading to a management change (51% and 57%). The average charge to the patient was $612.00 and the average cost to the hospital $452.00. Our results suggest that while physiologic changes are frequent during transport, they are also frequent in ICU patients as a consequence of the severity of illness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Impaired acetylcholine release in the inflamed rat intestine is T cell independent.

We investigated mechanisms underlying the suppression of [3H]acetylcholine ([3H]ACh) release from myenteric plexus-longitudinal muscle preparations of rats infected 6 days previously with Trichinella spiralis. There was a 73% suppression of KCl-evoked release of [3H]ACh in the jejunum, and a 76% suppression was observed in the worm-free ileum, indicating that the local presence of the parasite in the lumen is not prerequisite for the suppression of ACh release from the myenteric plexus. Treatment of rats with betamethasone (3 mg.kg-1.day-1 ip) during the infection prevented the acute inflammatory response and attenuated the suppression of [3H]-ACh release (from 73 to 22%) in the jejunum of infected rats. This finding is consistent with the hypothesis that the suppression of ACh release occurs as a result of the inflammatory process. Marked suppression of [3H]ACh release was also seen in T. spiralis-infected nude athymic rats, which were shown to lack functioning T lymphocytes. Thus changes in ACh release are not dependent on T lymphocytes. Taken in conjunction with our previously published study showing that altered muscle function in this model is T cell dependent, the results of the present study indicate that different components of the inflammatory response mediate changes in smooth muscle and myenteric nerves in the T.spiralis infected rat.

Acetylcholine↗
PubMed1992

Balloon mitral commissurotomy after previous surgical commissurotomy. The National Heart, Lung, and Blood Institute Balloon Valvuloplasty Registry participants.

BACKGROUND: Mitral restenosis after surgical mitral commissurotomy often occurs within 5-15 years, necessitating a repeat procedure. Balloon mitral commissurotomy (BMC) has been advocated as an alternative to repeat surgery for mitral restenosis. METHODS AND RESULTS: The purposes of this study are to determine the short- and intermediate-term outcomes of patients undergoing BMC after previous surgical commissurotomy, to compare these patients with those undergoing balloon mitral commissurotomy as an initial procedure, and to elucidate the multivariate determinants of acute procedural and clinical outcome. Of 738 patients undergoing BMC as part of the National Heart, Lung, and Blood Institute Balloon Valvuloplasty Registry, 133 underwent BMC after previous surgical mitral commissurotomy. Prospective data obtained included demographic, hemodynamic, echocardiographic, and clinical follow-up. BMC after previous surgical commissurotomy produced a significant reduction in transvalvular gradient from 13 +/- 5 to 6 +/- 3 mm Hg (p less than 0.0001) and an increase in mitral valve area from 1.0 +/- 0.3 to 1.8 +/- 0.8 cm2 (p less than 0.0001). BMC as an initial procedure increased valve area from 1.0 +/- 0.4 to 2.0 +/- 0.8 cm2 (p less than 0.0001) (p = 0.03 versus prior surgery). Baseline characteristics including mitral valve echo score were similar for both groups. Comparing 6-month status in patients with prior surgery to those without, 80% versus 90% were New York Heart Association (NYHA) functional class I or II (p = 0.004). Mortality was similar. In patients with previous mitral valve surgery, multivariate predictors of improvement in 6-month clinical status included the experience of the center (p = 0.006), lower echocardiographic score (p = 0.001), and lower left ventricular end-diastolic pressure (p = 0.008). Multivariate determinants of a final mitral valve area greater than or equal to 1.5 cm2 were a lower baseline NYHA functional class (p = 0.003) and lower mitral valve echocardiographic score (p = 0.008). CONCLUSIONS: BMC after previous surgical mitral commissurotomy results in similar hemodynamic changes as in patients undergoing BMC as an initial procedure. Symptomatic improvement at 6 months is slightly less frequent in prior commissurotomy patients. Patients with favorable valvular morphology and preserved left ventricular function who undergo BMC in experienced centers are most likely to achieve symptomatic improvement after previous surgical commissurotomy. In general, BMC is an effective treatment for mitral restenosis after previous surgical commissurotomy.

Catheterization↗
PubMed1992

Laboratory and clinical evaluation of the impact Uni-Vent 750 portable ventilator.

BACKGROUND: Transportation of critically ill, mechanically ventilated patients from intensive care units for diagnostic and therapeutic procedures has become common in the last decade. Maintenance of adequate oxygenation and ventilation during transport is essential. We evaluated the Impact Uni-Vent 750 portable ventilator in the laboratory and in the clinical arena to determine its usefulness during inhospital transport. MATERIALS & METHODS: In the laboratory, we determined the Uni-Vent 750's ability to assure tidal volume (VT) delivery in the face of decreasing compliance of a test lung and tested the alarm systems. Using a two-compartment lung model modified to simulate spontaneous breathing, we also evaluated the responsiveness of the demand valve. The clinical evaluation was accomplished by comparing arterial blood gas values and ventilator settings in the intensive care unit before transport to those during transport. RESULTS: As lung compliance was reduced from 0.1 to 0.02 mL/cm H2O [1.0 to 0.20 L/kPa], a slight, statistically insignificant decrease in delivered tidal volume was observed. All alarm systems operated according to manufacturer's specifications. The demand valve triggered appropriately with PEEP from 0 to 20 cm H2O [0 to 1.96 kPa]. Sensitivity settings less than -6 cm H2O [-0.59 kPa] sometimes resulted in inability to trigger the demand valve. During patient transport, arterial blood gas values and ventilator settings were comparable to those observed in the ICU. Because an FIO2 of 1.0 was used during transport, mean (SD) PaO2 was significantly greater 89 (26) vs 341 (78) [11.8 (3.5) vs 45.3 (10.4) kPa]. CONCLUSIONS: The Uni-Vent 750 is a reliable transport ventilator, capable of maintaining adequate oxygenation and ventilation in a majority of mechanically ventilated patients. The Uni-Vent 750's ability to (1) provide CMV, AMV, and SIMV; (2) provide low and high pressure alarms; and (3) provide PEEP compensation is unique among portable ventilators.

Adult↗
PubMed1992

The injured duodenum.

Duodenal injuries are relatively infrequent. A high index of suspicion is required because the retroperitoneal location of the duodenum makes the diagnosis of injuries difficult. Physical findings may be subtle and nonspecific. Contrast studies are often required to make the diagnosis. Options for operative management are outlined. Morbidity and mortality are related to associated injuries and delay in diagnosis.

Abdominal Injuries↗
PubMed1991

Expanding Medicare and employer plans to achieve universal health insurance.

This article presents a proposal for expanding Medicare and employer-based health insurance plans to achieve universal health insurance. Under this proposed health care financing system, employees would provide basic health insurance coverage to workers and dependents, or pay a payroll tax contribution toward the cost of their coverage under Medicare. States would have the option of buying all Medicaid beneficiaries and other poor individuals into Medicare by paying the Medicare premiums and cost sharing. Other uninsured individuals would be automatically covered by Medicare. Employer plans would incorporate Medicare's provider payment methods. This proposal would result in incremental federal governmental outlays on the order of $25 billion annually. These new federal budgetary costs would be met through a combination of premiums, employer payroll tax, income tax, and general tax revenues. The principal advantage of this plan is that it draws on the strengths of the current system while simplifying the benefit and provider payment structure and instituting innovations to promote efficiency.

Costs and Cost Analysis↗
PubMed1991

Total axillary lymphadenectomy in the management of breast cancer.

The optimal extent of axillary dissection in patients with breast cancer remains unclear. We report 278 total axillary lymphadenectomies (levels I, II, and III and Rotter's [interpectoral] nodes) that were performed in 264 closely followed up private patients. There have been no axillary recurrences to date (mean follow-up, 50 months). If only level I and II nodes had been removed, the false-negative staging error would have been only 2.6%. However, 29 (31.5%) of 92 pathological node-positive axillae contained apical and/or Rotter's metastases. The incidence of complications was comparable with that reported for partial lymphadenectomy. Arm lymphedema developed in 6% of nonirradiated patients; postoperative radiotherapy and gross nodal disease were significant risk factors for lymphedema. Total axillary lymphadenectomy largely prevents axillary, recurrence, eliminates the small staging error inherent in partial lymphadenectomy, and has acceptable morbidity, provided radiotherapy to the regional nodal areas is avoided.

Adult↗
PubMed1991

The effect of low dose dopamine on gut hemodynamics during PEEP ventilation for acute lung injury.

Mechanical ventilation with positive end-expiratory pressure (PEEP) diminishes gut and hepatic blood flow and redistributes cardiac output away from the splanchnic circulation. This flow-limited environment can aggravate underlying hypoperfusion and ischemia in the postinjury setting. To examine the effects of low dose dopamine on a lung injury PEEP model of gut hypoperfusion, six anesthetized, splenectomized canines were instrumented with arterial, pulmonary artery, portal vein, and hepatic vein catheters. Electromagnetic flow probes were placed around the hepatic artery and portal vein for continuous flow measurements. Gut and hepatic blood flow, oxygen delivery, oxygen consumption, and extraction ratio were calculated at four time points: baseline, 1 hr after lung injury with oleic acid, 1 hr after ventilation with 10 cm H2O PEEP, and 1 hr after the continuous infusion of dopamine. Portal flow and gut oxygen delivery fell significantly with the infusion of PEEP. These values returned to near baseline levels with the addition of dopamine. Gut oxygen extraction increased from 16 +/- 2% to 35 +/- 3% with PEEP but returned to near baseline with dopamine (20 +/- 4%, P less than 0.01 compared to PEEP). We conclude that dopamine improves blood flow and oxygen delivery to the gut in this flow-limited model. This may preserve splanchnic physiology during PEEP ventilation for acute lung injury.

Animals↗
PubMed1991

Migration to rural areas by HIV patients: impact on HIV-related healthcare use.

OBJECTIVE: To evaluate the impact of patient migration on human immunodeficiency virus (HIV)-related healthcare use in a rural setting. DESIGN: Data were collected on all patients seeking medical care related to HIV infection at The University of Iowa HIV/acquired immunodeficiency syndrome (AIDS) clinic. Information was collected related to patient care, stage of illness, prior and current residence, and clinic and hospital use. SETTING: An outpatient clinic in a university hospital offering primary and consultative medical care for persons with HIV infection. PATIENTS: All patients scheduled into clinic reported a previous positive HIV serologic test. RESULTS: Forty-five percent (81 of 181) of patients reported moving to Iowa, yet no more than 11% (n = 20) moved out of the state during the same period of observation. Of patients meeting the Centers for Disease Control criteria for AIDS, 24% were diagnosed prior to moving to Iowa (18 of 74). Twenty-seven percent of AIDS-related inpatient days of hospitalization and 19% of AIDS-related outpatient clinic visits were used by persons diagnosed in another state. Lifetime charges totalled for eight patients ranged from $24,873 to $232,556, with a mean of $109,934. CONCLUSIONS: A substantial portion of HIV-related healthcare in our rural area was used by individuals who had migrated to or back to Iowa. Further understanding of the reasons for and the extent of HIV patient migration to rural areas is needed.

Adult↗
PubMed1991

Atrial natriuretic peptide suppresses osmostimulated vasopressin release in young and elderly humans.

Atrial natriuretic peptide (ANP) may suppress vasopressin release, but the dynamics of this interaction as well as the influence of age have not been defined. We studied six or seven young (19-40 yr old) and seven elderly volunteers (65-83 yr old) under two circumstances: 1) after infusion of 5% saline (0.04 ml.kg-1.min-1) for 2 h and 2) after the same infusion given with simultaneous synthetic human ANP (0.05 micrograms.kg-1.min-1). Hypertonic saline alone produced a progressive rise in plasma vasopressin with increasing serum sodium. During hypertonic saline alone, vasopressin levels began to rise at an increment in serum sodium of 1.67 +/- 0.35 mM in the young and 1.43 +/- 0.32 mM in the elderly and rose linearly with increasing serum sodium. When ANP was infused with hypertonic saline (with peak ANP levels of approximately 1,000 pM), vasopressin levels began to rise at an increment in serum sodium of 4.43 +/- 0.67 mM in the young and 4.57 +/- 0.43 mM in the elderly (P less than 0.01 vs. saline alone). Furthermore, the vasopressin response for any given serum sodium was significantly reduced in both young and elderly subjects, resulting in a rightward displacement of the curve relating vasopressin response to sodium concentration (P less than 0.001). In conclusion, ANP not only suppresses vasopressin but raises the threshold for release of vasopressin in response to osmotic stimulation in both young and elderly individuals. High circulating ANP levels may be responsible in part for the suppression of vasopressin levels and water diuresis seen during states of volume expansion.

Adult↗
PubMed1991

Inequality and access to health care.

Health services research has laid the groundwork for ongoing policy debates over the shortcomings of the American health care system and the need for the expansion of health insurance protection. In the early 1970s, studies of inequality in access to medical care provided the basis for proposals for national health insurance. The examination of the impact of Medicare and Medicaid demonstrated the critical role of these governmental efforts in reducing inequalities in access to care. By the 1980s the focus of investigation turned to the impact of policies designed to contain the cost of health care on access to medical services by vulnerable populations. Documentation of the negative health outcomes that followed from restrictions on access to care has set the stage for a renewed debate over universal health insurance.

Cost Control↗