Search PubMed⌕ Search

Biomedical subjects

L K Weaver

Publications and source records attributed to L K Weaver.

9 recordsLinked to original sources
PubMed1992

A successful computerized protocol for clinical management of pressure control inverse ratio ventilation in ARDS patients.

We have developed a computerized protocol that provides a systematic approach for management of pressure control-inverse ratio ventilation (PCIRV). The protocols were used for 1,466 h in ten around-the-clock PCIRV evaluations on seven patients with severe adult respiratory distress syndrome (ARDS). Patient therapy was controlled by protocol 95 percent of the time (1,396 of 1,466 h) and 90 percent of the protocol instructions (1,937 of 2,158) were followed by the clinical staff. Of the 221 protocol instructions, 88 (39 percent) not followed were due to invalid PEEPi measurements. Compared with preceding values during CPPV, the expired minute ventilation was reduced by 27 percent during PCIRV while maintaining a pH that was not clinically different (mean difference in pH = 0.02). There was no difference in the PaO2, PEEPi, or the FIO2 between PCIRV and CPPV. The PEEP setting was reduced by 33 percent from 9 +/- 0.05 to 6 +/- 0.6 and the I:E ratio increased from 0.64 +/- 0.04 to 2.3 +/- 0.10. Peak airway pressure was reduced by 24 percent (from 59 +/- 1.5 to 45 +/- 0.6) and mean airway pressure increased by 27 percent (from 22 +/- 0.8 to 28 +/- 0.6) in PCIRV. Right atrial and pulmonary artery pressures were higher and cardiac output lower in PCIRV but blood pressure was unchanged. The success of this protocol has demonstrated the feasibility of using PEEPi as a primary control variable for oxygenation. This computerized PCIRV protocol should make the future use of PCIRV less mystifying, simpler, and more systematic.

Adult↗
PubMed1992

The adult respiratory distress syndrome. A report of survival and modifying factors.

The adult respiratory distress syndrome (ARDS) is a form of acute lung injury characterized by arterial hypoxemia, reduced thoracic compliance, normal pulmonary capillary wedge pressure, and diffuse infiltrates on chest roentgenograms. Mortality remains high and has been associated with sepsis, organ failure, age, and predisposing factors. We prospectively identified 215 ARDS patients over 34 months to examine how these factors influence outcome. One hundred two (47 percent) of 215 patients survived. Age 65 years or older was associated with a survival of 34 percent, which was statistically different from the 53 percent survival of those patients younger than 65 years (p = 0.02). Aspiration pneumonia as a predisposing factor of ARDS was associated with a better survival (p = 0.04). Survivors had statistically less organ failure and sepsis than did nonsurvivors (p less than 0.05). Cause of death was determined using the criteria of Montgomery et al for irreversible organ dysfunction. Forty-five (40 percent) of our patients died of respiratory failure (not sepsis). We conclude the following: (1) survival in our ARDS patients is different from previous reports; (2) the cause of death in our ARDS patients is different from that reported by Montgomery et al in 1985; and (3) multisystem organ failure, sepsis, age, and some predisposing factors of ARDS continue to be associated with decreased survival of ARDS patients.

Age Factors↗
PubMed1992

Normobaric measurement of arterial oxygen tension in subjects exposed to hyperbaric oxygen.

This study demonstrates the ability of an automated blood gas analyzer (Radiometer ABL 330) operated at atmospheric pressure to measure the arterial oxygen tension (PaO2) of ten healthy volunteers exposed to hyperbaric oxygen (HBO2) up to 3.0 atmospheres absolute. Arterial blood samples were aspirated from subjects compressed in a single-person hyperbaric chamber and were analyzed immediately in the blood gas analyzer. The subjects' values for PaO2 correlated with the calculated alveolar O2 tension (PAO2) (measured PaO2 = 0.827 x PAO2-15.1) (r2 = 0.97). Tonometric experiments indicated a difference between saline and blood PO2 measurements. We therefore derived a correction factor for blood measurements (corrected PaO2 = 0.908 x PAO2-52.4) (r2 = 0.98). These results compared favorably with PaO2 measurements made with blood gas analyzers calibrated inside walk-in hyperbaric chambers. We conclude that the PaO2 of normal subjects exposed to HBO2 can be measured accurately at atmospheric pressure with this automated blood gas analyzer. Prior to this study, hyperbaric PaO2 measurements could only be performed within walk-in chambers. Our observations generalize the normobaric measurement of hyperbaric PaO2 to patients treated in single-person and walk-in chambers.

Adult↗
PubMed1991

Noninvasive Doppler blood pressure monitoring in the monoplace hyperbaric chamber.

We describe a noninvasive method of monitoring blood pressure in the monoplace hyperbaric chamber. A standard blood pressure cuff was placed on the patient's arm. A Doppler probe, linked to an ultrasonic Doppler flow detector outside the chamber, was secured over the patient's radial artery. Cuff inflation tubing and the Doppler probe wires were passed into the chamber by modifying a standard disposable hyperbaric intravenous pass-through. Blood pressure readings were determined by inflating and slowly deflating the cuff from outside the chamber while observing the sphygmomanometer within the chamber and listening for the first audible flow signal from the Doppler detector, corresponding to the systolic blood pressure. To minimize the risk of fire in the oxygen-filled monoplace hyperbaric chamber, the patient, Doppler detector, and chamber were grounded. Doppler readings obtained from nine normal subjects whose arterial pressures were being measured with indwelling radial arterial catheters (approved as part of another study by the hospital's Investigational Review Board) compare closely with the subject's blood pressures measured with this noninvasive method: 114 +/- 7.6 mm Hg (mean +/- 1 SD) compared to 112 +/- 8.1 mm Hg, respectively (n = 92 measurements in 8 subjects). We conclude that this noninvasive method of monitoring blood pressure within the monoplace hyperbaric chamber is accurate and suitable for monoplace clinical purposes.

Blood Pressure↗
PubMed1988

Bilateral otorrhagia associated with continuous positive airway pressure.

A patient had bilateral tympanic membrane rupture and otorrhagia, an unusual complication of continuous positive airway pressure (CPAP). CPAP, applied by a bag/mask system using disposable spring valves, was used to treat acute pulmonary edema during volume resuscitation and vasopressin therapy for bleeding from esophageal varices.

Cough↗
PubMedDate not supplied

A strategy for development of computerized critical care decision support systems.

It is not enough to merely manage medical information. It is difficult to justify the cost of hospital information systems (HIS) or intensive care unit (ICU) patient data management systems (PDMS) on this basis alone. The real benefit of an integrated HIS or PDMS is in decision support. Although there are a variety of HIS and ICU PDMS systems available there are few that provide ICU decision support. The HELP system at the LDS Hospital is an example of a HIS which provides decision support on many different levels. In the ICU there are decision support tools for antibiotic therapy, nutritional management, and management of mechanical ventilation. Computer protocols for the management of mechanical ventilation (respiratory evaluation, ventilation, oxygenation, weaning and extubation) in patients with adult respiratory distress syndrome ((ARDS) have already been developed and clinically validated at the LDS Hospital. These protocols utilize the bedside intensive care unit (ICU) computer terminal to prompt the clinical care team with therapeutic and diagnostic suggestions. The protocols (in paper flow diagram and computerized form) have been used for over 40,000 hours in more than 125 adult respiratory distress syndrome (ARDS) patients. The protocols controlled care for 94% of the time. The remainder of the time patient care was not protocol controlled was a result of the patient being in states not covered by current protocol logic (e.g. hemodynamic instability, or transport for X-Ray studies). 52 of these ARDS patients met extra corporal membrane oxygenation (ECMO) criteria. The survival of the ECMO criteria ARDS patients was 41%, four times that expected (9%) from historical data (p less than 0.0002).(ABSTRACT TRUNCATED AT 250 WORDS)

Attitude of Health Personnel↗
PubMedDate not supplied

A computerized laboratory alerting system.

A computerized laboratory alerting system (CLAS) has been developed as part of an ongoing effort to improve the quality of care at LDS Hospital. The system identifies potentially life-threatening conditions on the basis of laboratory findings and then generates appropriate warnings and transmits them to clinicians. Use of the system has led to a significant increase in the proportion of patients in life-threatening situations who have received appropriate care (50.8% before implementation vs. 62.5% afterward, P less than 0.05). Among patients with hypokalemia, falling potassium levels, hyperkalemia, hypokalemia during treatment with digoxin, hyponatremia, falling sodium levels, hypernatremia, hypoglycemia, or hyperglycemia, the average length of time spent in the life-threatening situation has decreased from 30.4 to 15.7 hours (P less than 0.05) and the average length of stay has decreased from 14.6 to 8.8 days (P less than 0.05). There has been little change in the proportion of patients with findings indicating metabolic acidosis who have received appropriate care (32.3 vs. 34.6%). We conclude that CLAS has an important role in patient care at our hospital.

Artificial Intelligence↗