Lisa Hall Zimmerman

Detroit Medical Center, Detroit, Michigan, United States

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Publications (6)13.4 Total impact

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    ABSTRACT: Normally, end-tidal CO2 is within 2 mm Hg of arterial PO2 (PaCO2). However, if dead space in the lungs increases owing to shock with poor lung perfusion, the arterial-end tidal PCO2 difference [P(a-ET)CO2] increases. We have found that in severely injured patients, P(a-ET)CO2 of less than 10 mm Hg is associated with survival and P(a-ET)CO2 of greater than 16 mm Hg is usually fatal. Our initial studies suggested that intravenously administered bicarbonate increases P(a-ET)CO2. This retrospective therapeutic study evaluated the effects of intravenously administered bicarbonate in a cohort of 225 severely acidotic (arterial pH ≤ 7.10) trauma patients who underwent emergency surgery from 1989 through 2011. Patients were divided into groups: early deaths (<48 hours), deaths in the operating room, deaths within 48 hours, and survivors. Winter's formula was defined as PaCO2 = (HCO3) (1.5) + 8 ± 4. Of the 225 patients, the mean (SD) initial arterial pH was 6.92 (0.16) with HCO3 of 11.0 (3.5) mEq/L. According to the Winter's formula, PaCO2 should have been 24 (4) mm Hg but actually was 50 (14) mm Hg. In 73 patients, the effect of an average of two to eight vials of bicarbonate increased HCO3 from 10.5 (3.1) mEq/L to 16.8 (4.0) mEq/L. In addition, PaCO2 increased from 44 (9) mm Hg to 51 (11) mm Hg and end-tidal CO2 stayed relatively constant (26 [6] to 25 [5]). This resulted in a increase in P(a-ET)CO2 from 17 (9) mm Hg to 24 (13) mm Hg, affecting survival. In the final values after resuscitation, the P(a-ET)CO2 in the 75 patients who survived was 10 (6) mm Hg, while the 103 patients who died in the operating room or within 48 hours of surgery had a P(a-ET)CO2 of 23 (10) mm Hg (p < 0.001). In severely acidotic, critically injured patients, reducing the PaCO2 to less than 40 mm Hg and decreasing the P(a-ET)CO2 to 10 (6) mm Hg should be attempted, using as little HCO3 therapy as possible. Bicarbonate should be given only if severe acidosis persists despite resuscitation and if PaCO2 levels near those which are appropriate can be obtained. Therapeutic study, level IV.
    The journal of trauma and acute care surgery. 01/2013; 74(1):45-50.
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    ABSTRACT: Abstract Background: Catheter-related blood stream infections (CR-BSIs) are estimated to occur in 80,000 patients in intensive care units (ICUs) each year in the United States. We sought to determine the clinical utility of vascular catheter cultures in critically ill patients with suspected CR-BSI. Methods: We reviewed retrospectively all positive (≥15 colony forming units/roll) vascular catheter tip cultures (CTCs) documented over a four-year period in the ICUs of two hospitals. A CR-BSI was defined as matching positive blood and catheter cultures. The time interval between catheter removal and blood culture was recorded. Results: A total of 1,391 CTCs were obtained, of which 468 (34%) were positive and 143 (31% of the positive cultures) were associated with a diagnosis of CR-BSI. In 133 of these 143 cases (93%), the positive blood culture was obtained before or within 24 h after catheter removal and dictated antibiotic therapy. In only 10 of 143 cases (7%) did catheter removal and culture significantly (>1 day) precede the positive blood culture. In 55% of the CR-BSI cases, the catheter was removed empirically and close to the time of blood culture (-1.3±19.0 h). In the remaining 45%, the catheter was removed clinically (after a blood culture was positive), and this action was more remote in time (23.6±19.4 h; p<0.001 vs. empiric removal). Total microbiology laboratory costs for the CTCs were $75,300, and 600 microbiology technician hours were required. Conclusion: In an ICU patient population, only about one-third of vascular catheter cultures were positive, and only about one-third of the positive CTCs were associated with CR-BSI. Ninety-three percent of all CR-BSIs were identified by bacteremia either before or coinciding with catheter removal, and the results of the blood culture dictated antimicrobial therapy. Because CTCs rarely changed therapy, they may not be appropriate in the management of suspected CR-BSI in the ICU setting.
    Surgical Infections 07/2012; 13(4):245-9. · 1.87 Impact Factor
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    ABSTRACT: The incidence of vitamin D deficiency in critically ill patients is reported to be up to 50%, with a 3-fold increase in predicted mortality, but limited data exist concerning vitamin D deficiency in critically ill surgical patients. Sixty-six adult surgical intensive care unit patients who had 25-hydroxyvitamin D serum levels evaluated from January 2010 to February 2011 were prospectively identified. Patients were divided into groups according to vitamin D level (<20 vs ≥20 ng/mL). Of the 66 patients evaluated, 49 (74%) had vitamin D levels < 20 ng/mL, and 17 (26%) had vitamin D levels ≥ 20 ng/mL. Patients with vitamin D levels < 20 versus ≥ 20 ng/mL had longer lengths of hospital stay. Lengths of intensive care unit stay were clinically longer, although not significant. Infection rates tended to be higher (P = .09), and a higher incidence of sepsis was seen in the patients with vitamin D levels < 20 ng/mL. Vitamin D levels < 20 ng/mL have a significant impact on length of stay, organ dysfunction, and infection rates. More data are needed on the value of supplementation to improve these outcomes.
    American journal of surgery 12/2011; 203(3):379-82; discussion 382. · 2.36 Impact Factor
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    ABSTRACT: Appropriate antibiotic therapy and prompt drainage are essential for optimal results with abdominal abscesses. In this prospective study, 47 abdominal abscesses from 42 patients over 2 years who had percutaneous drainage were evaluated. Antibiotic concentrations were evaluated from the abscess fluid and correlated with clinical and microbiologic cure. Only 23% of patients had appropriate antibiotic selection with optimal concentrations for the bacteria recovered. Piperacillin/tazobactam, cefepime, and metronidazole provided adequate concentrations in all except the largest abscesses, whereas fluconazole required higher doses in all abscesses. Vancomycin and ciprofloxacin levels were inadequate in most abscesses. With gram-negative aerobes, the use of appropriate antibiotics resulted in a relatively higher incidence of presumed eradication (100% [4 of 4] vs 75% [9 of 12], P = .26). With ≥ 3 organisms identified, clinical failure was significant (58% vs 13%, P = .01). For optimal treatment, abdominal abscesses require prompt drainage and properly selected antibiotics at adequate doses. Essential information can be obtained from abscess cultures and their antibiotic concentrations.
    American journal of surgery 03/2011; 201(3):348-52; discussion 352. · 2.36 Impact Factor
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    ABSTRACT: The incidence of soft tissue infections from antimicrobial-resistant pathogens is increasing. This study evaluated the epidemiology of operatively drained soft tissue abscesses. This retrospective study evaluated 1,200 consecutive patients from 2002 to 2008 who underwent incision and drainage (I&D) in the main operating room. Patients were excluded for perirectal or hidradenitis infections. Of 1,200 consecutive cases with an I&D, 1,005 patients had intraoperative cultures. The 1,817 positive isolates included gram-positive aerobes (1,180 [65%]), gram-negative aerobes (207 [11%]), anaerobes (416 [23%]), and fungi (14 [1%]). The most prevalent organism was Staphylococcus aureus, 30% (536), with 80% (431) being methicillin-resistant S aureus (MRSA). MRSA was the predominant organism in all except the breast abscesses. Anaerobes were identified primarily in the breast in diabetics, and in trunk and extremity abscesses in intravenous drug users. The most frequently prescribed empiric antibiotic was ampicillin/sulbactam (66%). The initial empiric antibiotic did not cover MRSA (82%; P < .001), resistant gram-negative aerobes (24%), and anaerobes (26%). Gram-positive aerobes plus anaerobes represented approximately 80% of the pathogens in our series, with the anaerobic rates being underestimated. Empiric antibiotics should cover MRSA and anaerobes in patients with superficial abscesses drained operatively.
    Surgery 10/2009; 146(4):794-8; discussion 798-800. · 3.37 Impact Factor
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    ABSTRACT: In recent years there has been a rapid increase in the use of proton pump inhibitors. Our institution has recently had several shortages of IV pantoprazole, each lasting 7-10 days. The purpose of our study was to evaluate in-patient usage of IV pantoprazole. We hypothesized that hospitalized patients with upper gastrointestinal bleeding (GIB) or risk for stress ulcers inappropriately received IV pantoprazole based on current literature. This was a retrospective study of 165 consecutive in-patients identified as receiving pantoprazole from December 2004 to March 2005. Only patients receiving IV pantoprazole were included (n = 78). Data collected included demographics, indication and dosing of pantoprazole, admitting team (surgery vs. medicine), and risk factors for stress ulcers. Our study population had a mean age of 54 +/- 17 years and 62% were male. Overall, 45% (35/78) of patients receiving IV pantoprazole had an appropriate indication, and 19% (15/78) received the correct dose. Of the 78 patients, 43 (55%) were treated with pantoprazole for stress ulcer prophylaxis (SUP), and 35 (45%) patients were treated for GIB. We found that none of the 43 patients treated for SUP had an appropriate indication for pantoprazole, but all of the patients with GIB (35) had an appropriate indication. Of the 35 patients treated for GIB with pantoprazole, only 40% (14/35) received the correct dose. In all cases of incorrect dosing, the patients were underdosed. Pantoprazole is not being prescribed appropriately for stress ulcer prophylaxis in our patient population. Even in patients appropriately receiving pantoprazole the majority were prescribed an incorrect dose. Appropriate indications and dosing of pantoprazole could eliminate the shortages seen at our institution.
    Surgical Endoscopy 05/2008; 22(4):967-73. · 3.43 Impact Factor