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Publicaciones en Periódicos del Dr. Macias Los Angeles

The Blue Man: Burn From Muriatic Acid Combined With Chlorinated Paint in an Adult Pool Construction Worker

Published in Journal of Burn Care & Research, July 2013

Muriatic acid (hydrochloric acid), a common cleaning and resurfacing agent for concrete pools, can cause significant burn injuries. When coating a pool with chlorinated rubber-based paint, the pool surface is initially cleansed using 31.45% muriatic acid. Here we report a 50-year-old Hispanic male pool worker who, during the process of a pool resurfacing, experienced significant contact exposure to a combination of muriatic acid and blue chlorinated rubber-based paint. Confounding the clinical situation was the inability to efficiently remove the chemical secondary to the rubber-based nature of the paint. Additionally, vigorous attempts were made to remove the rubber paint using a variety of agents, including bacitracin, chlorhexidine soap, GOOP, and Johnson’s baby oil. Resultant injuries were devastating fourth-degree burns requiring an immediate operative excision and amputation. Despite aggressive operative intervention and resuscitation, he continued to have severe metabolic derangements and ultimately succumbed to his injuries. We present our attempts at debridement and the system in place to manage patients with complex chemical burns.

O’Cleireachain M.R., Macias L.H., Richey K.J., Pressman M.A., Shirah G.R., Caruso D.M., Foster K.N., Matthews M.R.

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Etiology of breast masses after autologous breast reconstruction.

Published in Annals of Surgical Oncology, February 2013

BACKGROUND: Determining the nature of a breast mass after autologous reconstruction can be difficult.

METHODS: A retrospective review of all autologous breast reconstructions was performed over 10 years. All postoperative breast masses were identified. Tumor characteristics, adjuvant treatment, timing of the development of the mass, and correlation with radiology were reviewed.

RESULTS: A total of 365 flaps were performed on 272 patients [253 deep inferior epigastric perforator (DIEP), 35 superficial inferior epigastric artery (SIEA), 22 muscle-sparing free transverse rectus abdominis myocutaneous (free MS-TRAM), 25 latissimus, and 30 pedicled TRAM]. Breast masses were identified in 66 breasts (18 %). The majority of these were from fat necrosis, occurring in 54 breasts (15 % overall; DIEP 13.4 %, SIEA 5.7 %, free MS-TRAM 15 %, latissimus 0 %, pedicled TRAM 47 %), first identified at a mean of 3 months. Recurrent carcinoma was diagnosed in 13 breasts (3.6 %). Factors associated with the postreconstruction mass representing recurrent carcinoma were later time period after reconstruction (mean 24 months), closer surgical margins, and lymphovascular invasion.

Radiographic imaging accurately diagnosed recurrent carcinoma in 11 (92 %) of 12 patients in whom it was utilized and suggested a benign diagnosis in all 16 patients with fat necrosis in whom it was utilized.

CONCLUSIONS: Breast masses frequently present after autologous reconstruction. Fat necrosis is the most common cause. Recurrent carcinoma can occur in the reconstructed breast and presents later. A higher index of suspicion for recurrence should accompany any mass in which prior lymphovascular invasion was present or if original margins were <1 cm. Radiographic imaging accurately identifies the cause of these masses.

Casey W.J. 3rd, Rebecca A.M., Silverman A., Macias L.H., Kreymerman P.A., Pockaj B.A., Gray R.J., Chang Y.H., Smith A.A.

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Computed tomographic angiography: assessing outcomes.

Published in Clinics in Plastic Surgery, April 2011

Perforator flaps are preferable for breast reconstruction after mastectomy in many patients. Preoperative imaging of the perforators and source vessels is desirable to reduce surgeon stress, limit donor and recipient site complications, and minimize operative time and associated costs. Computed tomographic angiography (CTA) has been shown to provide highly accurate representations of vascular anatomy with excellent spatial resolution. A critical review of the currently available literature was performed to identify the benefits of preoperative imaging (specifically CTA) in perforator flap reconstruction.

Casey W.J. 3rd, Rebecca A.M., Kreymerman P.A., Macias L.H.

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Treatment of bowler’s neuroma with digital nerve translocation.

Published in Hand: Official Journal of the American Association for Hand Surgery, September 2009

Bowler’s thumb presents as paresthesias or a neuroma involving the ulnar digital nerve of the thumb. Over 95 million people enjoy bowling worldwide with nearly 3 million certified league bowlers in the United States. While the incidence of Bowler’s thumb is unknown, it is an unrelenting nuisance for bowlers, and symptoms can be severe enough to prevent further sport participation. The condition can be managed nonoperatively with rest and splinting, but successful nonoperative treatment frequently requires discontinuation of bowling. The pressure on athletes to resume sports participation sooner and the possibility of nonoperative treatment failure mandate the need for development of a dependable surgical procedure for this condition. We present a case report of a successful surgical treatment by transposing the ulnar digital nerve dorsal to the adductor pollicis. The patient returned to manual labor and resumed bowling and is symptom free 3 years postsurgery.

Swanson S., Macias L.H., Smith A.A.

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The utility of diagnostic laparoscopy in the evaluation of anterior abdominal stab wounds

Published in American Journal of Surgery, December 2008

BACKGROUND: To assess if diagnostic laparoscopy (DL) is superior to nonoperative modes (serial abdominal examination with/without computed axial tomography [CAT] and diagnostic peritoneal lavage) in determining the need for therapeutic laparotomy (TL) after anterior abdominal stab wound (ASW).

METHODS: Retrospective review of ASW patients. Patients were divided into group A (DL/exploratory laparotomy) to identify peritoneal violation (PV) and group B (initial nonoperative modes).

RESULTS: Seventy-three patients met inclusion criteria. In group A (n = 38), 29 patients (76%) had PV by DL and underwent exploratory laparotomy. Only 10 (35%) underwent TL (sensitivity for PV = 100%; specificity and positive predictive value of PV in determining need for TL = 29% and 33%, respectively). In group B (n = 35), 7 patients (20%) underwent TL, yielding an improved specificity (96%) and positive predictive value (88%).

CONCLUSIONS: We find no role for DL in the evaluation of ASW patients solely to determine PV.

Kopelman T.R., O’Neill P.J., Macias L.H., Cox J.C., Matthews M.R., Drachman D.A.

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Patient comprehension and recall of laparoscopic surgery and outcomes in a non-English speaking population.

Published in Journal of the Society of Laparoendoscopic Surgeons, April -June 2007

BACKGROUND AND OBJECTIVES: The purpose of this study was to determine patient recall and comprehension after laparoscopic appendectomy in an underserved population. Laparoscopic surgery can lead to diagnostic uncertainty secondary to poor recall and variable port placement.

METHODS: After institutional review board approval, we identified a cohort of patients who underwent laparoscopic appendectomy from 2000 to 2004 at a single institution. We then attempted to contact the patients to conduct a 10-question telephone survey, which determined whether the patient spoke English or Spanish as a primary language, ethnicity, educational level, and questions about recall of perioperative events and diagnoses. If we could not reach the patient, we tried to call back on 2 different occasions.

RESULTS: Between 2000 and 2004, 186 patients underwent laparoscopic appendectomy. Of these, 65% were Hispanic. We found that only 17% of these patients returned for a postoperative visit. Only 19.3% could be contacted by phone. Forty-seven percent of the patients contacted by phone spoke Spanish exclusively. Overall 92% of patients contacted knew what operation they had, and gave their correct diagnosis.

CONCLUSIONS: The low percentage of patients available to follow-up makes this study statistically insignificant. However, we believe that fact in itself is important. In Southwestern states, we see a large migrant population. This highlights the need to communicate effectively with the patients at the time of surgery, which we speculate we did based on the percentage of patients that knew their diagnosis.

Clapp B., Jarmillo M., Vigil V., Macias L.H., Bouton M., Gallardo C, Kassir A.

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Factors affecting the successful management of intra-abdominal abscesses with antibiotics and the need for percutaneous drainage.

Published in Diseases of the Colon and Rectum, February 2006

PURPOSE: There is no definite consensus on the management of intra-abdominal abscesses in adults. This retrospective study evaluated the use of antibiotic therapy and percutaneous image-guided drainage in adult patients with intra-abdominal abscesses.

METHODS: A retrospective chart review of 114 patients with intra-abdominal abscesses was conducted. Data collected included patient demographics, presenting symptoms, radiographic interpretation, vital signs, antibiotic coverage, laboratory values, and details of the hospital course. Bivariate statistical tests were performed using the Wilcoxon rank-sum test, chi-squared test, or Fisher’s exact test, where appropriate.

RESULTS: Sixty-seven of 114 patients (59 percent) had intra-abdominal abscesses resulting from appendicitis, diverticulitis in 30 patients (26 percent), postoperative in 13 patients (11 percent), and undetermined in 4 patients (4 percent). Three patients (3 percent; 95 percent confidence interval, 1-8 percent) failed conservative management and underwent urgent operation. Sixty-one (54 percent; 95 percent confidence interval, 44-63 percent) patients improved with intravenous antibiotic therapy alone. Fifty patients (44 percent; 95 percent confidence interval, 35-54 percent) underwent image-guided percutaneous drainage after 48 to 72 hours of antibiotic therapy. Patients who improved on antibiotics alone had average abscess diameter of 4 cm, whereas patients who underwent percutaneous drainage had average diameter of 6.5 cm (P<0.0001). Maximal temperature at time of admission was 100.8 degrees F for antibiotic group and 101.2 degrees F for percutaneous drainage group (P=0.0067).

CONCLUSIONS: The majority of the patients with intra-abdominal abscesses improved with antibiotic therapy alone. Those patients with an abscess diameter>6.5 cm and temperature at admission>101.2 degrees F have higher likelihood of failing conservative therapy with antibiotics alone and requiring percutaneous drainage.

Kumar R.R., Kim J.T., Haukoos J.S., Macias L.H., Dixon M.R., Stamos M.J., Konyalian V.R.

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Diverticulitis: truly minimally invasive management.

Published in The American Surgeon, October 2004

The purpose of this study is to evaluate the treatment of patients with acute diverticulitis in the inpatient setting using minimal intervention. This was a retrospective study of 75 patients admitted over a 3-year period with acute diverticulitis as evidenced by computed tomography (CT) and clinical scenario. Of the patients enrolled, 24 (32%) had abscesses identified on their initial CT scan. An additional four patients had abscesses noted on a subsequent CT scan obtained because of lack of complete improvement with medical management, thus raising the total number of abscesses to 28 (37%). Of the patients with abscesses, 10 (36%) underwent drainage using a CT-guided percutaneous or ultrasound-guided transrectal approach an average of 6 days after admission. Of the 75 patients, five (7%) required operative intervention during the initial hospitalization for failure of medical management, two (40%) of whom had abscesses on presentation. The overall median length of hospitalization was 5 (interquartile range [IQR] 4-9) days, and 18 patients (24%) had recurrences during the study period. Our conservative approach to percutaneous and surgical intervention resulted in relatively low percutaneous drainage, a low operative rate, and a reasonable length of hospitalization and recurrence rate.

Macias L.H., Haukoos J.S., Dixon M.R., Sorial E., Arnell T.D., Stamos M.J., Kumar R.R.

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Autoreactive T cells can be protected from tolerance induction through competition by flanking determinants for access to class II MHC.

Published in Proceedings of the National Academy of Sciences of the United States of America, April 2003

It is not clear why the N-terminal autoantigenic determinant of myelin basic protein (MBP), Ac1-9, is dominant in the B1O.PL (H-2(u)) mouse, given its weak I-A(u)-MHC binding affinity. Similarly, how do high-affinity T cells specific for this determinant avoid negative selection? Because the MBP:1-9 sequence is embryonically expressed uniquely in the context of Golli-MBP, determinants were sought within the contiguous N-terminal “Golli” region that could out-compete MBP:1-9 for MHC binding, and thereby prevent negative selection of the public response to Ac1-9, shown here to be comprised of a V beta 8.2J beta 2.7 and a V beta 8.2J beta 2.4 expansion. Specifically, we demonstrate that Ac1-9 itself can be an effective inducer of central tolerance induction; however, in the context of Golli-MBP, Ac1-9 is flanked by determinants which prevent its display to autoreactive T cells. Our data support competitive capture as a means of protecting high-affinity, autoreactive T cells from central tolerance induction.

Maverakis E., Beech J., Stevens D.B., Ametani A., Brossay L., van den Elzen P., Mendoza R., Thai Q., Macias L.H., Ethell D., Campagnoni C.W., Campagnoni A.T., Sette A., Sercarz E.E.



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