Laser beam self-focusing in turbulent dissipative media.

A high-power laser beam propagating through a dielectric in the presence of fluctuations is subject to diffraction, dissipation, and optical Kerr nonlinearity. A method of moments was applied to a stochastic, nonlinear enveloped wave equation to analyze the evolution of the long-term spot radius. For propagation in atmospheric turbulence described by a Kolmogorov-von Kármán spectral density, the analysis was benchmarked against field experiments in the low-power limit and compared with simulation results in the high-power regime. Dissipation reduced the effect of self-focusing and led to chromatic aberration.

High-power lasers for directed-energy applications: reply.

The comment by Vorontsov and Weyrauch [Appl. Opt.55, 9950 (2016)APOPAI0003-693510.1364/AO.55.009950] is aimed at rebutting the critiques in Sprangle et al. [Appl. Opt.54, F201 (2015)APOPAI0003-693510.1364/AO.54.00F201] and Nelson et al. [Appl. Opt.55, 1757 (2016)APOPAI0003-693510.1364/AO.55.001757]. In the comment, Vorontsov and colleagues describe their experiments aimed at demonstrating the feasibility of coherent combining of lasers on a distant target, using relatively low-power lasers and a cooperative retro-reflective target. The Naval Research Laboratory has demonstrated the capability to project high power on a distant target by making use of an incoherent combining architecture. The proof-of-concept experiments were performed in a realistic environment without employing cooperative targets and without sophisticated adaptive optics instrumentation.

Effect of cardiopulmonary bypass on cefazolin disposition.

Cefazolin kinetics was studied in 8 patients the day before (PREOP), during (SURG), and the day after (POSTOP) cardiopulmonary bypass (CPB) surgery. PREOP (48.6 ml/min) and POSTOP (46.6 ml/min) total body clearances were of the same order and both were greater than the SURG (27.4 ml/min) total body clearance. Since cefazolin is almost entirely eliminated by the kidney, the lower SURG clearance is a result of reduced renal elimination, as confirmed by measuring cefazolin SURG (28.7 ml/min) and POSTOP (52.9 ml/min) renal clearance. The reduction in cefazolin renal elimination was the same throughout the surgical procedure, including the period of extracorporeal circulation. Cefazolin distribution was altered by the operative procedure as evidence by a higher SURG steady-state volume of distribution. This increase in apparent cefazolin distribution volume brought about by surgery was not seen with cephalothin, which was investigated by us in a similar group of patients. The different effect of CPB surgery on cefazolin and cephalothin distribution may be due to differences in plasma protein binding.

Cephalothin kinetics: before, during, and after cardiopulmonary bypass surgery.

Cephalothin kinetics was studied in 5 patients the day before (PREOP), during (SURG), and the day after (POSTOP) cardiopulmonary bypass surgery. The PREOP (114 ml/min) and SURG (94 ml/min) renal clearances were of the same order but both were less than POSTOP renal clearance (248 ml/min). Cephalothin total body clearance during operation was lower (p less than 0.01) than PREOP or POSTOP clearance, with decreased metabolic clearance the primary cause. There was reduction in cephalothin elimination throughout the surgical procedure, not only in the period of extracorporeal circulation, indicating that general anesthesia had a significant influence on drug disposition. The metabolite deacetylcephalothin was rapidly formed on all 3 days and its kinetic behavior paralleled that of the parent drug.

Commercial tattooing as a potentially important source of hepatitis C infection. Clinical epidemiology of 626 consecutive patients unaware of their hepatitis C serologic status.

Tattooing in commercial tattoo parlors is known to transmit blood-borne viral infections, including hepatitis C virus (HCV), in other countries, but its contribution to the high population prevalence of HCV infection in the United States has been incompletely evaluated. Risk factors for blood-borne infection were assessed by physician's interview of 626 consecutive patients undergoing medical evaluation for spinal problems in 1991 and 1992 while unaware of their HCV status. Later all were screened for HCV infection with enzyme-linked immunosorbent assay (EIA-1 and EIA-2), and positives were confirmed with second-generation recombinant immunoblot assay (RIBA). Forty-three patients were seropositive for HCV (sample prevalence 6.9%, population-standardized prevalence 2.8%). Logistic regression analysis identified 4 independent risk factors for HCV infection: injection-drug use (adjusted prevalence odds ratio [OR] = 23.0; 95% confidence intervals [CI] = 7.5-70.6), ancillary hospital jobs held by men (OR = 9.6; 95% CI = 3.8-24.3), tattoos from commercial tattoo parlors (OR = 6.5; 95% CI = 2.9-14.8), and drinking > or = 3 6-packs of beer per month (OR = 4.0; 95% CI = 1.8-8.7). If causal, these 4 risk factors account for 91% of HCV infections, with tattooing explaining 41%, heavy beer drinking 23%, injection-drug use 17%, and ancillary health care jobs for men 8%. Transfusions, promiscuous sexual activity, bone grafts, acupuncture, perinatal or intimate transmission in families, and other modes were not independently associated with serologic evidence of HCV infection. Unlikely to be explained by confounding or incomplete disclosure of other risk factors, tattooing in commercial tattoo parlors may have been responsible for more HCV infections than injection-drug use.

The mortality associated with pelvic fractures.

The mortality among 604 patients with pelvic fractures was 12%. Pedestrian accidents were the etiologic agent in 27% of the patients, but accounted for 49% of the deaths and for 73% of the deaths primarily due to pelvic fractures. Although 71 of the 72 patients who died sustained concomitant major injuries (mean, 3.1), 60% of the deaths (43 patients) were attributed entirely or in part to pelvic fractures. Of particular interest were the 26 patients in whom the pelvic fracture was the primary cause of death. Ninety-three percent were in shock or had clinical evidence of hypovolemia at the time of admission. Eighteen patients (69%) exsanguinated from their pelvic fractures shortly after hospital admission (mean, 9 hours). They were more elderly than the eight patients who survived their initial resuscitation, but subsequently died of sepsis or of renal failure (mean, 62 vs. 38 years). Sepsis arising in the pelvic hematoma and acute renal failure induced by pelvic hemorrhage and/or pelvic sepsis each accounted for 15% of the deaths. Ninety-one percent of the patients who died primarily of their pelvic fracture had a single or double break in the pelvic ring. Thirty-one precent had open pelvic fractures, and injury associated with a 50% mortality. Twenty-three percent had pelvic fracture related iliac or femoral vessel disruptions, an injury associated with a 75% mortality. Mortality in these patients clearly resulted from ineffective control of pelvic hemorrhage and from the inability to prevent sepsis in the pelvic hematoma.

A multicenter trial for resuscitation of injured patients with 7.5% sodium chloride. The effect of added dextran 70. The Multicenter Group for the Study of Hypertonic Saline in Trauma Patients.

OBJECTIVE: To evaluate the use of 250 mL of a 7.5% sodium chloride solution, both with and without added dextran 70, for the prehospital resuscitation of hypotensive trauma patients. DESIGN: Double-blind randomized trial. SETTING: Six trauma systems served by helicopter transport. PATIENTS: Injured patients with systolic blood pressures less than 90 mm Hg at any time in the field or during helicopter transport. INTERVENTIONS: Infusion of study solution, in the field or during transport, followed by conventional isotonic solutions as needed. Solutions studied in four cohorts were as follows: (1) lactated Ringer's; (2) 7.5% sodium chloride (hypertonic saline); (3) 7.5% sodium chloride combined with 6% dextran 70; and (4) 7.5% sodium chloride combined with 12% dextran 70. MAIN OUTCOME MEASURES: Blood pressure response; survival to time of hospital discharge among the treatment groups; and survival compared with that predicted by norms from the Major Trauma Outcome Study (MTOS). RESULTS: The mean (+/- SD) change in systolic blood pressure on arrival in the emergency department was significantly higher in the hypertonic saline solution group than that in the lactated Ringer's solution group (34 +/- 46 vs 11 +/- 49 mm Hg, P < .03). Overall survival in the four treatment groups was 49%, 60%, 56%, and 45% (not statistically significant). Survival in the hypertonic saline solution group, however, was significantly higher than that predicted by the MTOS norms (60% vs 48%, P < .001). Survival to hospital discharge in patients with baseline Glasgow Coma Scale scores of 8 or less was correlated with treatment group (P < .05 by logistic regression and P < .01 by Cox proportional-hazards analysis; with survival in the hypertonic saline solution group [34%] vs lactated Ringer's solution group [12%]). CONCLUSIONS: Prehospital infusion of 250 mL of 7.5% sodium chloride is associated with an increase in blood pressure and an increase in survival to hospital discharge compared with survival predicted by the MTOS norms. Patients with low baseline Glasgow Coma Scale scores seem to benefit the most from 7.5% sodium chloride resuscitation. Hypertonic saline solution without added dextran 70 is as effective as the more expensive solutions that contain dextran 70.

Traumatic lung herniation.

Traumatic lung herniation is a poorly described entity. An important factor in the etiology of these lesions is the relative lack of muscular support afforded by the anterior thorax. We report a case of blunt thoracic trauma complicated by an incarcerated lung herniation.

Buckshot colic.

A patient with a shotgun injury to the abdomen and kidney with delayed spontaneous ureteral passage of a shotgun pellet is reported. This rare complication "buckshot colic" usually can be treated nonoperatively. The term "buckshot colic" is clarified.

Major vascular injuries secondary to pelvic fractures: an unsolved clinical problem.

Twelve patients sustained sixteen pelvic fracture-related iliac and femoral arterial (5) and venous (11) injuries. Death was due in large part to delays in recognition and direct operative control of the major vascular disruption. Prompt operative exploration of all pedestrians admitted in hemorrhagic shock will open pelvic fractures characterized by a double break in the pelvic ring should reduce the 83 per cent mortality currently associated with this combination of injuries.

Modified Paul-Mikulicz ileocolostomy.

Primary anastomosis can often be safely performed between the distal ileum and colon after emergent right colectomy. However, when this is not possible, we believe that this ileocolostomy procedure can be performed safely and offers an attractive alternative to ileostomy. It differs from the classic Paul-Mikulicz procedure in that a common channel is created at the initial operation using a stapling device. This obviates the inherent risks of blindly placing bulky spur clamps between the colon and ileum in the postoperative period. Using this technique, we have encountered no staple line leaks, fluid or electrolyte imbalance, or skin excoriation in the postoperative or follow-up period of 26 patients. All ileocolostomies were closed through the ileocolostomy site without formal laparotomy and without complications.

Diagnostic peritoneal lavage: fourteen years and 2,586 patients later.

During a fourteen year period, diagnostic peritoneal lavage was 98.5 per cent accurate in determining the presence or absence of blunt intraabdominal injuries among 2,586 patients. Of these, 69.4 per cent had a negative lavage and 29.2 per cent a positive lavage. Six patients (0.2 per cent) had a false-positive lavage. Thirty-two patients (1.2 per cent) had a false-negative lavage; however, all but one of these patients underwent exploratory laparotomy on the basis of clinical acumen or other diagnostic tests.

Hypotension-induced post-traumatic necrosis of the right colon.

Necrosis of the right colon developed after hemorrhagic shock in six young traumatized patients who did not have colon injury. The mean duration of hypotension was 112 minutes, and the mean resuscitation fluid volume required was 22 liters. Signs of right colon necrosis appeared 2 to 7 days after injury (median 2 days). All patients survived right colectomy and ileocolostomy or ileostomy and mucous fistula. The cause of necrosis of the right colon after hemorrhagic shock from major trauma is not clear. Anatomic abnormalities in blood supply to the right colon or a derangement in the physiologic processes of the microcirculation of the right colon must be considered.

Early fasciotomy for acute clinically evident posttraumatic compartment syndrome.

Our understanding of the effectiveness of early decompressive fasciotomy for acute posttraumatic compartment syndrome is incomplete. Thirty-two patients who developed acute clinically evident compartment syndrome (23 in the leg, 9 in the forearm) were treated with decompressive fasciotomy an average of 16 hours after injury. Thirty patients (94 percent) underwent fasciotomy in conjunction with other urgent operative procedures mandated by concomitant injuries. Three patients required early amputation for a failed arterial repair. Only 2 of 29 patients with limb salvage (7 percent) had postoperative myoneural deficits after decompressive fasciotomy. Both of these patients had preoperative myoneural deficits. Decompressive fasciotomy before the development of ischemic myoneural deficits prevents the ischemic sequelae of acute clinically evident compartment syndrome.

The efficacy of magnetic resonance cholangiography for the evaluation of patients with suspected choledocholithiasis before laparoscopic cholecystectomy.

BACKGROUND: Endoscopic retrograde cholangiography is the most commonly utilized tool for the identification of common bile duct stones (CBDS) before laparoscopic cholecystectomy, whereas the role of magnetic resonance cholangiography (MRC) for patient evaluation before laparoscopic cholecystectomy is currently undefined. METHODS: We prospectively evaluated the efficacy of MRC for the identification of CBDS among patients with high risk for choledocholithiasis. Patient selection was based on clinical, sonographic, and laboratory criteria. Standard cholangiograms were obtained when possible for verification of MRC results. RESULTS: Ninety-nine patients underwent evaluation with preoperative MRC. CBDS was visualized in 30% of patients. MRC sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 85%, 90%, 77%, 94%, and 89%, respectively. CONCLUSIONS: MRC is useful for the evaluation of patients with suspected choledocholithiasis. Advantages of MRC include its noninvasive nature, ease of application, and accuracy in identifying and estimating the size of CBDS. Application of MRC in this setting reduces the need for diagnostic endoscopic retrograde cholangiography. Future investigations should be directed at the development of cost-effective utilization strategies for MRC application.

Major injury as a unique opportunity to initiate treatment in the alcoholic.

A prospective study was performed on the use of a standard outpatient intervention technique to induce inpatient alcoholic trauma patients into accepting alcoholism treatment. Interventions were performed on 17 trauma patients. All patients who underwent intervention accepted treatment and were immediately transferred to a 28-day inpatient treatment facility. Alcoholic trauma patients are highly susceptible to intervention for their disease. We found that intervention performed upon discharge from the trauma service successfully initiates alcoholism treatment.

Tampon occlusion of colostomy stoma during laparotomy.

A new technique for the occlusion of the colostomy stoma during colostomy takedown is prevented. Utilization of this technique prevents contamination and allows maintenance of colostomy length for anastomosis. It can be easily and safely performed.

Selective management of pediatric pelvic fractures: a conservative approach.

An analysis of clinical characteristics and pelvic fracture management in a recent 5-year period is presented. Ninety-eight percent of pelvic fractures were the result of a motor vehicle accident, which included 61% auto-pedestrian accidents. Seventy-nine percent of patients sustained one or more major injuries while 21% sustained an isolated pelvic fracture. Head injury was the most common concomitant injury (23% of patients). Forty-six percent of patients required blood transfusions (mean 15.8 mL/kg). Forty-one (72%) patients were treated with bedrest. The remainder were treated with traction (5), spica cast immobilization (5), open reduction and internal fixation (4), or anterior external fixation (2). Overall mortality was 14%. In comparing nonsurvivors with survivors there were significant differences in Modified Injury Severity Scores and Glasgow Coma Scores. The types of pelvic fractures that occur in children were found to be similar to those of adults. There was no significant difference in mortality among children with different types of pelvic fractures. In contrast to adults, pelvic fracture hemorrhage was not a major contributing cause of death in this series of patients. All eight deaths were secondary to severe closed head injury.