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Biomedical subjects

H C Polk

Publications and source records attributed to H C Polk.

At least 55 records · Page 3Linked to original sources
PubMed1997

Cardiac herniation producing tamponade: the critical role of early diagnosis.

BACKGROUND: Rupture of the pleuropericardium (PP) occurs rarely, with most patients dying of associated injuries before arriving at the hospital. Among patients who initially survive, the diagnosis is often delayed until cardiogenic shock secondary to cardiac herniation is evident. METHODS: The records of 10 patients with PP lacerations and cardiac herniations were reviewed. RESULTS: All but one patient had a normal chest x-ray (CXR) film on admission. After the patients became symptomatic, seven of nine had abnormal findings on CXR film demonstrating herniation of the heart into the left hemithorax. The other two patients underwent surgery without a repeat CXR film. Except for one who was taken directly to the operating room, all patients had been previously stabilized before developing cardiogenic shock, on average 9 hours after admission. Operative therapy was closure of the pericardium for five patients and completion pericardiotomy for the others. All survivors developed significant complications, and four of them died. CONCLUSIONS: The diagnosis of PP rupture should be considered for patients with multiple trauma who develop sudden and unexpected cardiogenic shock after their initial condition has been stabilized. A repeat CXR film is diagnostic in most cases and should be used as the most efficient and expeditious route to making the diagnosis.

Accidents, Traffic↗
PubMed1997

Phagocytosis and oxidative-burst response of planktonic Staphylococcus epidermidis RP62A and its non-slime-producing variant in human neutrophils.

The ability of bacterial organisms to produce an extracellular polysaccharide matrix known as slime has been associated with increased virulence and delayed infections in various prosthetic implants. Within a biofilm, this slime may protect the embedded bacteria from host defense mechanisms, especially phagocytosis by polymorphonuclear leukocytes. To determine whether planktonic Staphylococcus epidermidis is protected in a similar way, a novel flow cytometric assay was performed, measuring ingestion and adherence during phagocytosis and the production of superoxide during oxidative burst. Hydrophobicity was determined by hydrophobic interaction chromatography. Slime-producing S. epidermidis RP62A and its phenotypic variant, non-slime-producing RP62A-NA, were compared. The results showed increased phagocytosis of RP62A at 2, 5, 10, and 30 min; increased adherence of RP62A at 30 s and 30 min; and increased superoxide production of RP62A after 2 min. Decreased hydrophobicity of RP62A over RP62A-NA was correlated with a hydrophilic slime coat. The data argue that the host aggressively combats slime-producing S. epidermidis. This biological phenomenon is potentially important during bacteremia to prevent further adhesion, accumulation, and the genesis of a bacterial biofilm on implants or tissue surfaces.

Animals↗
PubMed1997

Absorbable, delayed-release antibiotic beads reduce surgical wound infection.

Absorbable, polyglycolic acid (PGA) beads were evaluated as a new vehicle for local antibiotic delivery. Incisions on the dorsa of guinea pigs were contaminated with 1 x 10(8) Escherichia coli and 1 x 10(8) Staphylococcus aureus. PGA beads containing either minocycline, amikacin, or no antibiotic (placebo) were placed into these wounds and compared to animals treated with systemic minocycline or amikacin alone. The diameter of wound erythema was measured daily for 7 days. Serial blood and wound quantitative cultures were obtained, and serum and wound antibiotic concentrations were determined. Both minocycline-PGA and amikacin-PGA-treated wounds exhibited less erythema than placebo-PGA wounds (P < 0.05). All minocycline-PGA and amikacin-PGA-treated wounds healed primarily, whereas 67 per cent of placebo-PGA wounds developed purulence, dehisced, and healed secondarily. Local antibiotic delivery was more effective than systemic administration in reducing wound erythema and the number of bacteria in wound quantitative cultures. E. coli and S. aureus were quantitatively reduced (P < 0.05) in wounds of antibiotic PGA-treated animals compared to those in placebo-PGA-treated and systemic minocycline and systemic amikacin-treated animals. Measurable minocycline and amikacin concentrations were present in antibiotic-PGA-treated wounds through day 3, without detectable serum levels. Delayed-release, absorbable, antibiotic-containing PGA beads effectively prevent infection in contaminated wounds and have the advantage of not requiring vehicle removal.

Amikacin↗
PubMed1996

Efficacy of blood cultures in the critically ill surgical patient.

BACKGROUND: Blood cultures are commonly obtained to delineate an infectious process in the ill surgical patient with fever, leukocytosis, or other septic parameters. We studied how often bacteremia was diagnosed, whether a positive blood culture changed therapy, and the cost analysis of this practice. METHODS: A heterogenous adult population of 158 patients at high risk for bacteremia was retrospectively reviewed. Blood cultures were not obtained in 37 patients, and thus they were excluded from further study. RESULTS: We obtained 1040 blood cultures in 121 patients. Forty-eight patients (40%) had 122 positive cultures; 20 of these patients had only false-positive cultures. Thus 28 patients (23%) had 82 cultures that represented true bacteremia. Among clinical events, only antibiotic changes and interventions occurred significantly more often as a result of a positive blood culture (p < or = 0.05). No change in therapy occurred in most patients with both positive and negative cultures. Cost for all cultures was $60,058 or $1,251 per positive culture and $1,877 per clinical therapeutic event change. CONCLUSIONS: Routine ordering of blood cultures is not cost-effective, rarely alters or provides therapeutic direction, and appears not to affect mortality. Obtaining clinically indicated blood cultures as a secondary rather than a primary diagnostic measure is suggested.

Adolescent↗
PubMed1996

CD14 expression in injured patients correlates with outcome.

OBJECTIVE: The authors determined the correlation between monocyte CD14 expression and outcome in severely injured patients. SUMMARY BACKGROUND DATA: Human leukocyte antigen-DR (HLA-DR) expression CD14 positive monocytes correlates with the development of major infection and subsequent death in severely injured patients. Recent studies show that CD14 is not only a marker for mature monocytes, but also is an important endotoxin/lipopolysaccharide receptor. METHODS: Flow cytometry data obtained by dual staining techniques (CD14 and HLA-DR) of monocytes in 213 severely injured patients were analyzed over a 30-day period. Outcome criteria included survival and the development of both major and minor infections. RESULTS: The percentage of cells expressing CD14 (%CD14) correlated with clinical outcome, reaching significance (p < 0.05) between noninfected survivors (n = 74) and nonsurvivors (n = 21) at days 3, 7, 11, 17, 24, and 30. At days 3, 7, and 17, the %CD14 also was different between noninfected and infected survivors. After 7 days, differences were only seen between survivors and nonsurvivors (p < 0.05). The mean fluorescence intensity (MC CD14) in monocytes of all patients was significantly reduced at day 3 compared with day 1 and remained low for 30 days (p < 0.05). The nonsurvivor group had consistently low MC CD14 values, which were significant at day 5 (p < 0.05). CONCLUSIONS: In addition to HLA-DR expression, CD14 expression on monocytes is an indicator of clinical outcome after injury and could represent a more precise target for treatment.

Adolescent↗
PubMed1996

Sepsis and septic complications in the surgical patient: who is at risk?

The estimation of patients who are at risk for infection, sepsis, and organ dysfunction/failure is crucial not only for inclusion in treatment algorithms but also for entry into appropriate clinical trials of prophylaxis and therapy. Patients on the surgical service who have sustained major trauma or who have undergone transplantation are clearly at the greatest risk. Other immunosuppressed patients at risk for sepsis include those receiving myelosuppressive chemotherapy, those with overwhelming malignancy, and those who suffer from cirrhosis, diabetes mellitus, and severe malnutrition. We have focused on the trauma patient, in whom infection and organ failure are the leading causes of late death, major morbidity, and prolonged hospital stay. Over a 10 yr period, we have surveyed a number of host defense parameters that pertain to an adequate immune response and found a suppressed response shortly after injury in many. All were anergic to a standard skin test panel, and the duration of anergy varied with the clinical course of infection. Immunoglobulin levels were low after major injury as well as specific antibodies to both Gram-positive and Gram-negative organisms. The ability of serum from the trauma patient to opsonize heat-killed bacteria was markedly depressed 24 h after injury in those patients who subsequently died of infection. Class II major histocompatibility antigen expression on peripheral blood monocytes correlated closely with clinical outcome and led to the development of an Outcome Predictive Score. This score can identify patients within hours of hospitalization who are at risk of subsequently developing overt clinical infection and sepsis. Intervention then can be applied to such at-risk populations prior to the onset of sepsis and to evaluate the efficacy of prophylaxis. Patients in whom prophylaxis fails could be eligible for trials of therapeutic intervention as well.

Cytokines↗
PubMed1996

Continuing search for solutions to trauma associated infections.

The surgeon's unending efforts to control infection in the surgical patient have reopened old avenues in the last years of this century. While there remains much to be learned about ideal antibiotic use, much contemporary energy is devoted to a clarification of the host's non-specific antimicrobial defense system, looking for the salient and critical defect and evaluating putative therapies. The laboratory bench yields a myriad of defects and likely solutions; the clinical scenario has been far less forgiving, and a raft of well-planned and executed clinical trials have produced half an answer. The wisest current strategy in surgical infection control is a judicious critique of failed clinical trials and the prospective development of precise reassessment, seeking a definable valuable outcome. We must continue to monitor the laboratory bench and should apply these concepts to the recalcitrant pneumonia that has been the most common cause of death in surgical patients for the past 30 years.

Anti-Bacterial Agents↗
PubMed1995

Hemorrhagic shock-induced alterations in circulating and bronchoalveolar macrophage nitric oxide production.

Local and systemic host immune functions are markedly altered after trauma. Activated macrophages (M phi) are the major effector cells of protective immunity, mediated in part by nitric oxide (NO). This study was undertaken to determine the effects of hemorrhage (HEM) on M phi cytotoxic function as measured by NO production. Male Sprague-Dawley 350- to 400-g rats were studied. Sham animals only had their carotid artery exposed and ligated. Hemorrhaged animals had carotid artery cannulation followed by HEM to SBP of 40 mmHg, sustained for 45 min, followed by resuscitation with shed blood and crystalloid. Recovered animals were sacrificed (n = 5 each) at 6, 12, 24, and 72 hr after HEM; blood and alveolar M phi were then isolated and examined. A monolayer of adherent M phi was examined for NO production in resting state and after in vitro LPS stimulation. (1) HEM resulted in significantly reduced alveolar M phi yield at 12 and 24 hr. (2) HEM increased NO production by circulating M phi at 24 hr (P < 0.05), while alveolar M phi had significantly increased NO production at all time points after HEM (P < 0.05). (3) LPS stimulation significantly increased NO production in both circulating and alveolar M phi in sham animals and 6 hr after HEM but not at any other times. We therefore conclude that HEM causes early and prolonged activation of NO production by alveolar M phi and delayed and brief activation of circulating M phi. Alveolar and circulating M phi are unable to significantly increase NO production in response to LPS stimulation during the later phases of HEM.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Hyperthermic isolated limb perfusion increases circulating levels of inflammatory cytokines.

Hyperthermic isolated limb perfusion is an established method of treatment for regionally advanced melanoma. Recent studies suggest that exogenously administered cytokines potentiate tumor response in patients with in-transit melanoma. We hypothesized that isolated limb perfusion induces an immunogenic response characterized by increased circulating levels of cytokines in the pump circuit, potentially contributing to the antitumor effect. We obtained blood samples from the perfusion circuit and systemic circulation at various intervals from patients undergoing isolated chemotherapeutic perfusion for melanoma. Samples were analyzed for serum cytokine profiles by enzyme-linked immunosorbent assay. When compared with baseline values, significant increases in serum levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor (TNF) occurred within the perfusion circuit during isolated limb perfusion (P < 0.05). In addition, there was a corresponding increase in IL-8 within the systemic circulation at the 60-min interval (P < 0.05), suggesting some degree of leakage from the isolated circuit due to the extremely high levels of IL-8 in the perfusion circuit. A transient but insignificant decrease in circulating levels of neutrophils was also observed during the perfusion process, which may be attributed to margination. Increased levels of cytokines IL-6, IL-8, and TNF occurred within the isolated circuit during hyperthermic limb perfusion and may contribute to tumor response seen in patients treated with isolated limb perfusion.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Outcome of amputations in patients with major burns.

There is little mention in the literature of the outcome of patients who require amputations for large surface area burns. To determine their outcome, we devised a case-control study. Fifteen patients who underwent amputations between 1984 and 1993 at the University of Louisville Burn Unit were analysed and compared to a similarly injured control group. Both groups represented severely burned patients with high total body surface areas involvement. Apache II scores, and per cent of inhalation injuries. The results showed a 60 per cent survival rate in each group. Unlike previous reports on electrical burns, the amputations in this series of primarily thermal injuries (12 of 15 patients) were performed late in the hospital course (mean, 15 days) and after previous attempts at limb salvage (mean, two procedures). By eliminating either non-viable or infected tissue, amputations served a role in obtaining a respectable survival rate for these severely injured patients that also compared favourably with the control group.

APACHE↗
PubMed1995

Are learning objectives useful in evaluating medical school course and instructor performance?

We tested the hypothesis that learning objectives could be used to evaluate course and instructor effectiveness. Ninety-seven third-year medical students who had their surgical clerkship or their medical clerkship as their first clinical rotation were compared. The surgery clerks received 171 urologic learning objectives. Students taking the surgical clerkship had significantly higher postclerkship recognition of the learning objectives than did medical clerkship students. One year later, these students were again surveyed to determine whether they still knew the correct response to the learning objective. The follow-up survey showed that 50% of the students recognized objectives covered in five of the eight urology lectures, while the other lectures were not effective. Students who recognized the objective on the postclerkship evaluation were more likely to think the objective had been taught on this follow-up survey. These data suggest that learning objectives are useful for evaluating course and instructor effectiveness.

Adult↗
PubMed1995

Antibiotic penetration of experimental intra-abdominal abscesses.

Intra-abdominal abscess is seldom adequately treated by systemic antibiotics alone and often requires surgical or computed tomography-guided drainage for resolution. Abscess penetration of six currently used antibiotics was examined in a murine intra-abdominal abscess model. Ampicillin/sulbactam, cefmetazole, clindamycin, and trospectomycin penetrated intra-abdominal abscesses to a greater degree than cefoxitin and ceftriaxone. Abscess pus antibiotic levels were not significantly higher after multiple doses than after a single dose. Pus antibiotic levels below the MIC90 for Bacteroides and E. coli within intra-abdominal abscess were observed for most antibiotics with the doses used in this study. Selection of antibiotics with a greater ability to penetrate abscess may be important in optimally treating patients with abdominal infection.

Abdominal Abscess↗