Search PubMed⌕ Search

Biomedical subjects

D A Story

Publications and source records attributed to D A Story.

29 records · Page 2Linked to original sources
PubMed2000

The effect of microwave heating on the acidity of 0.9% saline in 1 litre and 100 mL polyvinyl chloride packaging.

OBJECTIVE: Microwave warming of intravenous crystalloid solutions is an accepted practice in operating suites and emergency departments. These intravenous solutions are stored in polyvinyl chloride (PVC) and are known to be acidic. Some of this acidity may be from PVC packaging. We asked if microwave heating affected the acidity of 0.9% saline solution in 1 litre and 100 mL PVC bags. METHODS: Seven 1 litre bags were heated in an 800 Watt microwave for 2 minutes each and seven 100 mL bags were heated for 30 seconds each. After overnight cooling to room temperature, pH and temperature were measured and compared with two control groups of 7 unheated bags. RESULTS: There was no significant difference between the pH of heated and unheated solutions of saline. The median pH of the 1 litre bags were 5.01 (control) and 5.02 (heated). The median pH of the 100 mL bags were 4.58 (control) and 4.59 (heated). Post hoc, we found the 100 mL bags were more acidic than the 1 litre bags by a median difference of 0.43 pH units (P = 0.002). CONCLUSIONS: Microwave heating does not change the acidity of 0.9% saline in 1 litre or 100 mL PVC packaging.

Journal Article↗
PubMed2000

The epidemiology of major early adverse physiological events after surgery.

OBJECTIVE: To study the incidence of major post-operative adverse physiological events in a tertiary hospital. METHODS: Non-cardiac, surgical in-patients were studied for the first three post-operative days. Daily assessment was by patient visit, chart review and laboratory result analysis. Pre-determined diagnostic criteria for the identification of adverse physiological events were used. RESULTS: One hundred and seven patients were studied. The mean age was 61 +/- 20 years. Forty-four were female and 63 were male. Pre-operatively, 48 patients had one or more of 34 different co-morbidities. Forty three (40%) of the 107 patients had one or more major adverse physiological events. These events included hypotension 24 (22%), altered mental state 16 (15%), oliguria 9 (8.4%), abnormal heart rate 8 (7.5%) and abnormal respiratory rate 5 (4.7%). Morbidity associated with these events included respiratory failure 5 (4.7%), prolonged altered mental state 5, (4.7%), and septic shock 3 (2.8%). There were two deaths. Adverse physiological events were common in thoracic 5/9 (56%), neurosurgical 4/10 (40%) and vascular 8/13 (62%) patients. Prolonged altered mental state was most common among orthopaedic patients 5/22 (23%). Adverse physiological events were more frequent in the elderly than the young: 14/52 (27%) in those who were less than 65 years of age versus 29/55 (53%) in those who were 65 years and older (p < 0.025). There was a non-significant increase (p < 0.1) in adverse physiological events in patients having emergency surgery 16/28 (57%) compared with those having elective surgery 27/79 (34%). CONCLUSIONS: This study reveals a high incidence of post-operative adverse physiological events in surgical patients in a university teaching hospital and identifies several high-risk groups. Further studies are needed to define the clinical significance of these events, appropriate management and prognosis.

Journal Article↗
PubMed1999

Trace element and vitamin concentrations and losses in critically ill patients treated with continuous venovenous hemofiltration.

OBJECTIVES: To measure the blood concentrations of a number of trace elements and vitamins in critically ill patients and examine their elimination by continuous venovenous hemofiltration (CVVH). SETTING: Intensive care unit of a tertiary institution. DESIGN: Prospective, controlled, clinical study. PATIENTS: Eight critically ill patients requiring renal replacement therapy, nine patients requiring intensive care treatment but not requiring renal replacement therapy, and nine healthy controls. INTERVENTIONS: Measurement of trace element and vitamin concentrations in blood and ultrafiltrate. MEASUREMENTS AND MAIN RESULTS: Compared with normal volunteers, critically ill patients requiring CVVH had significantly lower median blood concentrations of vitamin C, vitamin E, selenium, and zinc. During the first 24 hrs of CVVH, there were no changes in the trace element and vitamin concentrations in blood, nor were there differences between pre- and postfilter samples. Micronutrient losses in the ultrafiltrate were small or undetectable except for Vitamin C, chromium, and copper. Compared with normal volunteers, critically ill patients not requiring CVVH also had significantly lower median blood concentrations of vitamin C, vitamin E, selenium, and zinc. There were no differences between the two critically ill groups. CONCLUSIONS: The clinical significance of the reductions in blood concentrations of selenium, zinc, vitamin C, and vitamin E in critically ill patients and the ultrafiltrate losses of Vitamin C, copper, and chromium remains unclear.

Ascorbic Acid Deficiency↗
PubMed1999

Intravenous fluid administration and controversies in Acid-base.

OBJECTIVE: To present an overview of acidosis following intravenous fluid infusion and to highlight the current controversy in acid-base physiology. DATA SOURCES: Articles and reviews from peer reviewed journals and books on acid-base physiology and post infusion acidosis. SUMMARY OF REVIEW: Infusion of intravenous fluids can produce an acidosis particularly in the setting of large volume infusion. The explanation of this phenomenon has centred around dilution of plasma bicarbonate. An alternative explanation can be found in the work of Peter Stewart, which highlights the use of strong ion difference in assessing metabolic acidosis. The Stewart approach differs from the traditional Henderson-Hasselbalch approach to acid-base. Further study is required to determine which approach is correct. Solutions containing base anions such as lactate may attenuate such an infusion acidosis. Animal and clinical studies using Hartmann's solution and Plasmalyte 148 support this idea. CONCLUSIONS: There is controversy regarding mechanisms in acid-base physiology. The clinical significance of post infusion acidosis is unclear, however use of Hartmann's solution may minimize the acidosis.

Journal Article↗
PubMed1998

Performance of the Atom 235 syringe infusion pump under hyperbaric conditions.

Inotrope-dependent patients may become haemodynamically unstable during treatment in the hyperbaric chamber. One possible cause is altered performance of infusion devices. We tested six Atom 235 syringe infusion pumps under hyperbaric conditions of 2.8 atmospheres absolute in a multiplace chamber using a gravimetric method. There was a small but significant reduction in infused volume during a thirty-minute period including compression time. We concluded that altered inotrope delivery may explain at least some of the haemodynamic instability sometimes seen, although a physiologic effect of hyperbaric treatment cannot be excluded.

Humans↗
PubMed1997

Continuous measurement of arterial and end-tidal carbon dioxide during cardiac surgery: Pa-ETCO2 gradient.

There have been reports of a negative arterial to end-tidal CO2 gradient (Pa-ETCO2) during cardiac surgery, so we used capnometry and an intravascular blood gas sensor (Paratrend 7) to continuously monitor this gradient in 20 cardiac surgical patients. We also compared the values obtained from this sensor with those obtained from a standard blood gas analyser at seven time points. We found a significant change in Pa-ETCO2 after cardiopulmonary bypass (P < 0.001) though we were unable to demonstrate a negative Pa-ETCO2 at any time (95% CI 0-14%). There was clinically acceptable agreement between laboratory and Paratrend 7 measurements during and after cardiac surgery.

Aged↗
PubMed1993

End-tidal oxygen measurement compared with patient factor assessment for determining preoxygenation time.

Time to adequate preoxygenation was assessed in 200 elective surgical patients, using measurement of end-tidal oxygen concentration. A variety of patient factors were assessed as to their ability to predict the time required to preoxygenate a patient. Of the 200 patients, 23 (11.5%) were unable to be adequately preoxygenated; most of these cases were due to a poor mask fit. The average time for preoxygenation was 154 seconds (range 43-364 seconds). Of those patients who could be preoxygenated, 46 (23%) required more than three minutes. Although a regression equation could be constructed to calculate time required for preoxygenation, the wide standard errors of the coefficients preclude a clinically useful predictive equation. We thus found that we could not accurately predict time required for preoxygenation and that a routine three minutes preoxygenation may not be sufficient for many patients. However, the measurement of end-tidal oxygen concentration is a very useful method of determining the end-point for preoxygenation.

Adolescent↗
PubMed1991

Atrial natriuretic factor during hypoxia and mild exercise.

The effect of hypoxia on plasma atrial natriuretic factor (ANF), plasma renin activity (PRA), and plasma aldosterone concentration (PAC) was evaluated during 2 h of treadmill exercise at 2 km/h, 0 grade at sea level. Six male subjects exercised on 2 separate days during normoxia (21% O2) and hypoxia (13.3 +/- 0.3% O2). No significant changes in ANF or PRA occurred during either normoxic or hypoxic exercise. However, PAC fell significantly during normoxic exercise (17.5 +/- 3.6 vs. 12.7 +/- 2.6 ng/dl, p less than 0.05) but not during hypoxic exercise. Serum potassium concentration fell during hypoxic exercise (5.0 +/- 0.1 vs. 4.4 +/- 0.1 mmol/l, p less than 0.05) along with bicarbonate (27.8 +/- 0.7 vs. 25.8 +/- 0.6 mmol/l, p less than 0.01). Between normoxic and hypoxic studies there was a significantly higher heart rate during hypoxic exercise (78 +/- 5 vs. 90 +/- 6 b/min, p less than 0.01). The major conclusion of this study is that hypoxia resulting in arterial oxygen saturations of 81 +/- 0.7% does not affect plasma atrial natriuretic factor levels during mild exercise in normal male subjects.

Adult↗