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Biomedical subjects

E G King

Publications and source records attributed to E G King.

At least 19 recordsLinked to original sources
PubMed1992

Biofilms on indwelling vascular catheters.

BACKGROUND AND METHODS: Some bacteria have a natural tendency to adhere to available surfaces and to form biofilms. Biofilms have been demonstrated on right heart flow-directed catheters, endocardial pacemaker leads, urinary catheters, and other medical devices. In this study, we examined arterial and central venous catheters that had been in place in ICU patients between 1 and 14 days for the presence of bacterial biofilms by scanning electron microscopy, transmission electron microscopy, and a special scraping/sonication bacterial recovery technique. The data taken from these processes were compared with skin entry site swabs and blood cultures and correlated with patient data on infection, bacterial colonization, and antibiotic use. RESULTS: Extensive biofilm formation was demonstrated by scanning electron microscopy on all 42 arterial and 26 central venous catheters. Bacteria were seen within the biofilms on 69% (29/42) of the arterial and 88% (23/26) of the central venous catheters. These two direct methods for the detection of biofilm bacteria on the catheter surfaces demonstrated the presence of adherent organisms on 81% of devices examined. Some catheters that had been in place for only 1 day were colonized by bacterial biofilms. Biofilm scraped from catheter surfaces and dispersed by mixing and sonication yielded cultures (32% of catheters) of predominantly skin bacteria. In a few instances, the recovery of bacteria from biofilms on vascular catheters coincided with positive cultures from skin entry site swabs and/or from the blood of the patient, but there was no significant correlation between bacterial recovery from the catheter surface, entry site, and/or patients' blood. CONCLUSIONS: Direct microscopic examination of 68 vascular catheters that had been in place 1 to 14 days showed that most (81%) were colonized by bacteria growing in slime-enclosed biofilms. In many cases, this colonization of catheter surfaces could be confirmed by special biofilm culture recovery methods. Although the clinical importance of bacterial biofilms on catheter surfaces is speculative, their presence and potential to serve as a nidus for infection and bacteremia in critically ill immunocompromised hosts are cause for concern.

Alberta↗
PubMed1992

Evaluation of strategies for central venous catheter replacement.

OBJECTIVES: To assess the consequences of leaving a bacterially colonized central venous catheter in place and to compare the effects of three catheter replacement strategies for catheter repair control in an animal model. DESIGN: Prospective study. SETTING: Laboratory and animal facility of a large university. SUBJECTS: Eighteen healthy, female, adult sheep. INTERVENTIONS: Radiopaque-siliconized elastomer central venous catheters were inserted into the jugular veins and colonized with either Escherichia coli or Staphylococcus epidermidis. After 7 days of infection, the catheters were either: a) exchanged using a guidewire; b) removed and replaced with a new catheter in a new jugular vein site after a 48-hr interval; or c) exchanged using a guidewire and antibiotics (tobramycin, cephaloridine) injected into the catheter. Animals were euthanized 7 days after insertion of the new catheter. Quantitative microbiology was performed on blood samples collected daily from the catheters and a peripheral vein, as well as from catheters and tissue recovered from the sheep at the time of autopsy. MEASUREMENTS AND MAIN RESULT: When catheters were changed using a guidewire, they became colonized by bacteria within 48 hrs, and the sheep had embolic pneumonia and vegetative endocarditis at autopsy. Similar consequences were observed when antibiotics were administered into the catheter lumen. If colonized catheters were removed and a new catheter was inserted after a 48-hr interval, recolonization, pneumonia, and endocarditis were not observed. CONCLUSIONS: Replacement of a biofilm-colonized central venous catheter over a guidewire is associated with rapid colonization of the replacement catheter and production of detached, slime-enclosed, antibiotic-resistant aggregates that colonize other catheters or initiate endocarditis or pneumonia by dissemination in the bloodstream.

Animals↗
PubMed1991

The value of submucous needle aspiration in the prediction of surgical resection line of bronchogenic carcinoma.

The fiberoptic bronchoscope was used to perform a series of SMNAs from the tumor site in the bronchial tree toward the carina to decide on an appropriate surgical line of resection in 20 patients. The line of resection was examined histologically for tumor invasion. Of the 20 patients who underwent surgery 16 had lobectomies and four had pneumonectomies. Eighteen patients had no evidence of tumor invasion at the surgical resection site. Of the remaining two, one had a cancer-positive SMNA proximal to the resection line and demonstrated tumor cells in the surgical resection line. The second demonstrated tumor cells in the right lower and upper lobes with sparing of the right bronchus intermedius. This patient underwent lobectomy with subsequent resection of the remaining right upper lobe. On the basis of this experience we conclude that SMNA is effective in predicting the optimal surgical line of resection in lung carcinoma.

Biopsy, Needle↗
PubMed1991

Guidewire catheter change in central venous catheter biofilm formation in a burn population.

This study was designed to assess the risk of colonization and biofilm formation of central venous catheters left in situ for seven days vs those changed over a guidewire at three days and removed at seven days. Colonization was determined using scanning and transmission electron microscopy and compared to a special scraping/sonication culture method. Thirty-one catheters were examined, and no difference was found between catheters left in situ (9 of 16 colonized) and those changed over a guidewire (11 of 15 colonized). Colonization rates rose significantly from 4 of 15 catheters at the time of guidewire change to 11 of 15 at 7 days (p less than 0.001). Of the catheters defined as colonized by SEM, the special culture technique showed bacterial growth in only 35 percent, making a negative culture result of dubious value in ruling out catheter colonization. No beneficial effect of guidewire changes in reducing colonization could be demonstrated.

Bacterial Adhesion↗
PubMed1990

Predictive equation for assessing energy expenditure in mechanically ventilated critically ill patients.

Traditional formulas, such as the Harris and Benedict equation (HBE), do not accurately predict energy expenditure (EE) in mechanically ventilated, critically ill patients (MVCIP). The purpose of this study was to develop a predictive EE equation to assess EE requirements in MVCIP. A portable metabolic cart was used to measure indirectly EE in 112 MVCIP. Patients were studied at rest and for 30 min on the first or second day of ICU admission. No nutrition was received during the study period. Variables investigated were: age, BSA, Acute Physiology and Chronic Health Evaluation (APACHE II) score, sepsis score, Injury Severity Score (ISS), respiratory rate (f), tidal volume (VT), minute ventilation, mean arterial pressure, heart rate, body temperature (Temp), and outcome. Patient age, APACHE II score, sepsis score, ISS, and BSA were 50 +/- 20 yr, 16 +/- 7, 11 +/- 6, 32 +/- 14, and 1.80 +/- 0.27 m2, respectively. Correlation and multiple regression analyses were used with EE as the dependent variable. A predictive equation (EE [kcal/day] = 945 BSA -6.4 age + 108 Temp + 24.2 f + 817 VT -4349) was determined from variables that contributed greater than 3% to the variance of EE: BSA (52%), age (10%), f (5%), VT (5%), and Temp (3%). The HBE underestimated measured EE by 34 +/- 19% and in 79 patients deviated greater than 15%. Using the new equation, only 15 patients' EE deviated greater than 15% from measured EE. The new predictive EE equation can accurately assess EE in MVCIP.

Adult↗
PubMed1989

Energy expenditure associated with CPAP and T-piece spontaneous ventilatory trials. Changes following prolonged mechanical ventilation.

The use of portable metabolic carts to assess energy expenditure (EE) by measuring oxygen consumption (VO2) and carbon dioxide production (VCO2) has recently been applied to patients undergoing weaning from mechanical ventilation. The VO2 and EE can be used to estimate changes in the work of breathing (WOB) associated with different weaning strategies. The purpose of this study was to use VO2 and EE to assess changes in the WOB when assisted mechanical ventilation (AMV) was replaced with two spontaneous ventilatory trial (SVT) techniques: continuous positive airway pressure (CPAP) and T-piece. Nine difficult-to-wean patients were studied during the initial weaning period following 26 +/- 18 days (mean +/- SD) of mechanical ventilatory support. The VO2 and EE during all AMV were 296 +/- 75 ml/min and 2069 +/- 519 kcal/day, respectively. Compared to the baseline AMV levels, during CPAP overall VO2 and EE increased 14 percent and 13 percent, respectively, and during T-piece overall VO2 and EE increased 20 percent and 19 percent, respectively. Respiration rate (f) increased and tidal volume (VT) decreased during both SVTs compared to AMV although no significant change in minute ventilation was seen. The WOB, as judged from changes in VO2, was only 5 percent higher during T-piece compared to CPAP; however, patients tolerated an average of only 141 +/- 45 min on T-piece vs 165 +/- 29 minutes on CPAP. We conclude that during the initial weaning stages in patients who have received prolonged mechanical ventilatory support, the WOB associated with SVTs is increased compared to AMV but that the WOB associated with T-piece is not significantly greater than that for CPAP.

Adult↗
PubMed1988

Hemodynamic and pathologic effects of prostacyclin on oleic acid-induced pulmonary injury.

Oleic acid (OA) injection into the lungs of dogs produces pulmonary edema and decreased cardiac output, and the result is combined hypoxic and stagnant hypoxia. Prostacyclin (PGI2) has some effects that may be beneficial in the alleviation of hypoxia. We studied 18 anesthetized dogs that were divided into three groups: (1) Six dogs acted as controls and did not receive OA or PGI2, (2) six dogs received OA but no PGI2, and (3) six dogs were first given OA and 1 hour later an infusion of PGI2 (100 ng/kg/min) was started and continued for 4 hours. All dogs were killed at the end of the study and their lungs were removed for weighing and preparation for microscopic examination. Compared with controls, OA caused a low cardiac output, high systemic and pulmonary vascular resistance, and increased right-to-left intrapulmonary shunt. The group that received OA and PGI2 demonstrated a well-maintained cardiac output and a low systemic vascular resistance. Right-to-left intrapulmonary shunt, however, increased in these dogs compared with the dogs not given PGI2. All animals given OA had similar wet/dry lung weights and histologic appearances. Our results suggest that the only beneficial effect of PGI2 in OA-induced lung injury is to improve the stagnant hypoxia, but this is associated with an aggravation of the hypoxic hypoxia. The result of these competing effects appears to be a mild overall improvement in oxygen delivery as suggested by the slightly higher mixed venous PO2 in the group that received PGI2.

Animals↗
PubMed1987

Comparison of high-frequency chest wall compression with conventional mechanical ventilation in cats.

Six anesthetized paralyzed cats with normal lungs were ventilated by high-frequency chest wall compression (HFCWC) at 5 Hz using a single-chamber circumferential cuff enclosing the thorax from the axillae to the xiphisternum. PaCO2 during HFCWC + PEEP (3 cm H2O) was significantly (p less than .0005) lower compared with conventional mechanical ventilation (CMV). End-expiratory lung volume (VL) during HFCWC + PEEP was significantly (p less than .001) lower than VL during CMV + PEEP but was higher than VL during CMV without PEEP. After the cats' lungs were stiffened by repeated saline lavage, CMV + PEEP at a mean airway pressure (Paw) of 10 cm H2O was compared with HFCWC + continuous positive airway pressure (CPAP) at an equal or lower Paw. A significant decrease in PaCO2 (p less than .02) during HFCWC occurred but no significant differences were observed in PaO2, VL, or compliance. Arterial BP and cardiac output were similar between CMV + PEEP and HFCWC + CPAP. In cats with normal lungs, VL can be maintained by applying CPAP during HFCWC, and in those with injured lungs, HFCWC + CPAP produces comparable gas exchange at a Paw equal to or lower than that used during CMV + PEEP.

Animals↗
PubMed1987

Biofilms on right heart flow-directed catheters.

This study was designed to detect biofilm and bacteria on right heart flow-directed catheters using scanning electron microscopy and culture following scraping and dispersion of biofilm by sonication. We examined 20 consecutive catheters removed from 18 critically ill patients, an average of 2.6 days after insertion. On scanning electron microscopy, all catheters were found to be covered by a biofilm, with bacteria visible on 50 percent of them. Cultures of specimens from 40 percent of the catheters grew skin organisms (Staphylococcus warneri, Diphtheroid), anaerobes (Propionibacterium), and other potential pathogens (Proteus vulgaris, Enterobacter cloacae). Combination of the two techniques produced a bacterial detection rate of 75 percent. This study demonstrates that the presence of biofilm with bacterial adherence is common on right heart flow-directed catheters. The phenomenon could play a significant role in endogenous infection in critically ill patients.

Bacteria↗
PubMed1986

Validation of a compact system for measuring gas exchange.

Measuring gas exchange in critically ill patients can provide valuable information on their nutritional status and energy expenditure. Several semiautomated machines are available for measuring oxygen consumption (VO2) and carbon dioxide production (VCO2). This study evaluated, under controlled laboratory conditions, a Gould 9000 IV prototype designed for use with mechanically ventilated patients. Various VO2 and VCO2 values were simulated at different combinations of frequency, tidal volume, minute ventilation, and inspired oxygen fraction (FIO2). Variations in frequency, tidal volume, and minute ventilation had no significant effect on the measured VO2 and VCO2, but FIO2 had a dramatic effect on the accuracy of VO2. Errors in measured VO2 were 2.6%, 3.5%, 5.9%, and 16.9% at FIO2 values of 0.22, 0.40, 0.60, and 0.80, respectively. Addition of a dead space to the spirometer dump port (to prevent room-air contamination) corrected a larger error initially found. The accuracy of VCO2 was +/- 2.6%.

Carbon Dioxide↗
PubMed1979

Influence of mechanical ventilation and pulmonary disease on pulmonary artery pressure monitoring.

Mechanical ventilation and respiratory disease impose both theoretical and practical limitations on the interpretation of hemodynamic measurements. To properly interpret such information a thorough understanding of the circulatory changes associated with normal breathing, mechanical ventilation and respiratory disease is vital. There are a variety of factors involved in patients with obstructive lung disease and those receiving mechanical ventilation that complicate the usual interpretation of hemodynamic data obtained from flow-directed catheters. An awareness of the potential pitfalls of hemodynamic monitoring in such situations is important in the efficient use of the hemodynamic data obtained.

Blood Pressure↗
PubMed1979

Severe thrombocytopenia probably due to acute folic acid deficiency.

Thirteen patients with significant hemorrhage, severe thrombocytopenia, and megaloblastic bone marrows are described. Unusual features of this problem included its acute onset, frequent absence of the typical peripheral blood changes of megaloblastic anemia, normal serum B12 levels, and serum folates which were often not clearly abnormal. Most patients were critically ill and common clinical features included reduced dietary intake, renal failure, renal dialysis, the postoperative state, and sepsis. These clinical features, the laboratory findings, and a platelet increase in most patients after folate therapy lead to the conclusion that this problem is probably due to acute folic acid deficiency. Possible explanations for the atypical laboratory findings include the acuteness of onset, recent blood transfusion therapy, and impaired folate utilization. This problem may be relatively common. Because of its potential clinical importance, rapid onset, and attendent diagnostic difficulties, prophylactic folic acid is recommended in the clinical setting described.

Acute Disease↗
PubMed1977

Hydrogen sulfide poisoning: review of 5 years' experience.

The workforce of Alberta, a province rich in fossil fuel, faces an increasing risk of exposure to hydrogen sulfide (H2S). Basic knowledge of the population exposed during the years 1969 to 1973 inclusive was accumulated to identify the immediate medical and management problems. Data were recorded from three sources of records: the Workers' Compensation Board of Alberta, the Alberta Hospital Services Commission and the provincial coroner's office. There were 221 cases of exposure to H2S. The overall mortality was 6%; 5% of victims were dead on arrival at hospital. Admission to hospital was required for 65% of the victims arriving at a hospital emergency room (78% of the 221). Acute problems were coma, dysequilibrium and respiratory insufficiency with pulmonary edema. Increased attention to cardiopulmonary resuscitation at the exposure site and during transportation to hospital is necessary to reduce the mortality from H2S exposure. No long-term adverse effects were apparent in the survivors.

Accidents, Occupational↗