Individualizing amikacin regimens: accurate method to achieve therapeutic concentrations

Amikacin's pharmacokinetics and dosage requirements were studied in 98 patients receiving treatment for gram-negative infections. A wide interpatient variation in the kinetic parameters of the drug occurred in all patients and in patients who had normal serum creatinine levels or normal creatinine clearance. The half-life ranged from 0.7 to 14.4 h in 74 patients who had normal serum creatinine levels and from 0.7 to 7.2 h in 37 patients who had normal creatinine clearance. The necessary daily dose to obtain therapeutic serum concentrations ranged from 1.25 to 57 mg/kg in patients with normal serum creatinine levels and from 10 to 57 mg/kg in patients with normal creatinine clearance. In four patients (4%), a significant change in baseline serum creatinine level (greater than 0.5 mg/dl) occurred during or after treatment, which may have been amikacin-associated toxicity. Overt ototoxicity occurred in one patient. The method of individualizing dosage regimens provided a clinically useful means of rapidly attaining therapeutic peak and trough serum concentrations.

Amikacin pharmacokinetics: wide interpatient variation in 98 patients

The disposition of amikacin was studied in 98 patients receiving treatment for severe gram-negative sepsis. Several factors were identified which were significantly related to the drug's elimination rate. These included renal function (r = .67), age (r = -.55), distribution volume (r = .34), and weight (r = -.31). These variables explain 62% of the variance (R2) in elimination rate constant when combined in a multiple regression model. The drug's half-life demonstrated considerable interpatient variation in patients with a normal serum creatinine (.68-14.4 hrs) or with a normal creatinine clearance (.68-7.2 hrs). The drug's distribution volume ranged from .08 to .48 L/Kg. The drug's clearance varied from 6.5 to 200 mL/hr/kg for patients with a normal serum creatinine and 17.8 to 200 mL/hr/kg for patients with a normal creatinine clearance. The interpatient variation in the drug's kinetic parameters is a concerning clinical problem. Measuring serum amikacin concentrations and adjusting dosage regimens are necessary to achieve desired peak and trough serum concentrations.

Initial dosage regimens of gentamicin in patients with burns

For 95 patients with burns the gentamicin dosage regimen necessary to achieve optimal serum concentrations was determined. Individual elimination rates and distribution volumes for gentamicin were determined and correlated with renal function parameters and age. In patients with burns who had normal serum creatinine levels (less than 1.5 mg/dl), gentamicin clearance and thus dosage regimens can be stratified by age. Gentamicin's clearance decreased inversely with age. Initial dosage guidelines were calculated for different age groups of patients with normal levels of serum creatinine. The guidelines were developed to assist the clinician in attaining therapeutic concentrations with initial doses of gentamicin. Therapeutic serum concentrations were reached in most patients with burns dosed by these guidelines. Serum gentamicin concentrations should always be monitored during therapy, and dosages should be adjusted to ensure optimal concentrations during the course of therapy.

Blunt trauma in adults and children: a comparative analysis

Trauma remains the major cause of death in children and young adults. Adult and pediatric patients differ significantly in both mechanism of and physiologic response to injury. We reviewed the records of all consecutive adult and pediatric blunt trauma patients admitted to a major metropolitan trauma center for a 10-year period. An extensive computerized database has been maintained for all patients since 1977. A comparative statistical analysis of mechanism of injury, specific organ injury, and clinical outcome was performed. Altogether, 1,722 adults and 289 children were treated during the study period. Blunt trauma accounted for 82.8% of adult and 94.3% of pediatric injury (p = 0.00005), and only these patients were considered for analysis. Diagnostic peritoneal lavage was performed in 249 children and 1,464 adults, with a respective accuracy of 99.6% and 97.2%. Mechanism of injury was comparable for both groups, although children were far more likely to be injured by falls, bicycle accidents, or struck by an automobile. Comparative analysis of specific injuries demonstrated significantly fewer pediatric chest (p = 0.001), spine (p = 0.03), and pelvic (p = 0.003) injuries. Central nervous system (CNS) injury in children was a strong determinant of outcome: serious pediatric CNS trauma was associated with a tenfold increase in mortality. Mortality for children in the absence of CNS injury was less than 3%. Spinal injury also appeared to be a predictor of poor outcome in the pediatric population, with an associated mortality of greater than 50%. Overall, survival was age independent (82.5% of adults and 85.8% of children were survivors.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermal injury effects on drug disposition: a prospective study with piperacillin

The disposition of piperacillin was prospectively evaluated in nine severely burned patients who had normal renal and hepatic function. Wide interpatient variations were demonstrated in the drug's distribution volume, half-life, and clearance, with mean (+/- SD) values of 55.0 (+/- 44.2) liters, 3.6 (+/- 5.2) hours, and 14.9 (+/- 6.3) liters/hour, respectively. Piperacillin clearance was best explained by patient factors other than age, renal function, and the percentage of body surface area burns. Piperacillin disposition was related to the patients' serum albumin, total bilirubin, blood urea nitrogen, and the amount of urea nitrogen excreted daily in urine. Altered piperacillin disposition thus appeared to occur secondary to changes in the patients' physiologic and metabolic state caused by injury-related stress and fluid therapy. The patient's physiologic and metabolic response to injury, along with age and renal function, should be considered when instituting treatment with piperacillin or other agents cleared from the body in a similar manner.

Effects of treatment and the metabolic response to injury on drug clearance: a prospective study with piperacillin

The disposition of piperacillin was prospectively evaluated in 11 critically ill surgical patients who had no evidence of pre-existing renal and hepatic disease. Interpatient variations were demonstrated in the drug's half-life, distribution volume, and clearance, with values of 1.50 +/- 2.05 (SD) h, 25.0 +/- 17.2 L, and 23.8 +/- 17.2 L/h, respectively. Variations in piperacillin disposition were best explained by serum concentrations of albumin, total protein, and bilirubin, and the amount of urea nitrogen excreted daily in urine. Age and renal function were moderately associated with piperacillin elimination rate and clearance. Altered piperacillin disposition thus appeared to occur as secondary to changes in the patients' physiologic and metabolic state caused by injury-related stress and fluid/colloid therapy. These alterations may necessitate dosage modifications to achieve optimal patient response when treating patients with piperacillin as well as with other similar drugs eliminated via renal and nonrenal routes.

An unusual cause of massive non-surgical pneumoperitoneum: case report

A case of pneumoperitoneum due to cocaine abuse is presented. Although most commonly associated with surgical disease, pneumoperitoneum may actually be a manifestation of non-surgical intrathoracic pathology. In this patient percutaneous diagnostic peritoneal lavage resulted in return of a large quantity of air and was negative for bleeding or contamination.

Laser Doppler flowmetry and cardiac output in critically ill surgical patients

Laser Doppler flowmetry (LDF) accurately measures cutaneous microcirculatory blood flow. We compared change in LDF flow to change in thermodilution cardiac output in ten critically ill surgical patients. A subset analysis of three patients with low cardiac output (cardiac index less than 2 L/min X m2) showed no correlation. We conclude that, under these study conditions, LDF microcirculatory flow did not reflect macrocirculatory flow. We conjecture that overcoming cutaneous vasoregulation with thermal vasodilation may obviate these results.

Comparison of radioimmunoassay and fluorescent polarization immunoassay for quantitative determination of vancomycin concentrations in serum

A new fluorescent polarization immunoassay (Abbott Laboratories, Diagnostics Division, North Chicago, Ill.) was compared with a standard radioimmunoassay (American Diagnostics Corp., Newport Beach, Calif.) in 34 patients being treated with vancomycin. A total of 123 serum samples were divided and quantitatively analyzed for vancomycin by both assay methods. The results obtained indicated that the two assay methods are comparable (y = 1.01x - 0.81; r = 0.99).

Clinical use of a one-compartment model for determining netilmicin pharmacokinetic parameters and dosage recommendations

To determine netilmicin pharmacokinetic parameters and to evaluate the use of a one-compartment pharmacokinetic model, 32 patients receiving netilmicin for suspected gram-negative sepsis were enrolled in our study protocol. Dose and dosage interval for each patient were determined by one-compartment pharmacokinetic analysis of six postinfusion netilmicin serum samples (0.16, 0.33, 0.5, 1, 2, and 3 h) measured by radioimmunoassay. In patients with a normal serum creatinine, mean (+/- SD) half-life and distribution volume were 1.9 +/- 1.1 h and 0.2 +/- 0.8 L/kg, respectively. The average daily dose and mean days of therapy were 5.1 +/- 1.9 mg/kg/day for 7.3 +/- 2.8 days. Serum creatinine changes of greater than 0.5 mg% occurred in 2 of 28 (7%) patients. Substantial variability in half-life and distribution volume occurred in patients. Initial dosages of 5-7 mg/kg/day in divided dosages seem appropriate for adult patients with normal renal function. Monitoring of serum levels and adjustment of dose and dosage interval are necessary to maintain therapeutic antibiotic concentrations. As with other aminoglycosides, the one-compartment pharmacokinetic model proved to be an acceptable method for measuring netilmicin pharmacokinetic parameters and individualizing therapy.

Blunt injury to the colon and rectum

One hundred nine patients suffering blunt injury to the colon or rectum were treated between 1 January 1970 and 31 December 1980. Vehicular accidents accounted for 90% of the injuries and 91% of the fatalities. Multiple system injury predominated, with survivors averaging 1.9 and nonsurvivors 3.8 injuries/patient. Six cases were complicated by abdominal sepsis directly related to their colon injury. There were no deaths and no episodes of colon-related abdominal sepsis among patients with isolated colon trauma. Of the 32 patients not surviving, four (3.7%), died as a direct result of their colon injury. Three of the four deaths appear to have been preventable.

Wide interpatient variations in gentamicin dose requirements for geriatric patients

Substantial interpatient variations were demonstrated in the daily doses required to obtain therapeutic gentamicin sulfate serum concentrations in 417 elderly patients. Dosages ranged from 0.3 to 22.0 mg/kg/day in patients with a normal serum creatinine level. Twenty-five percent of these patients required daily doses higher than the standard regimen of 5 mg/kg/day, and 33% required less than 3 mg/kg/day. The drug half-lives in these patients ranged from 0.3 to 32.7 hours, compared with previous reports of 2.5 to four hours. The distribution volumes of these patients ranged from 0.07 to 0.53 L/kg, compared with reported values of 0.20 to 0.25 L/kg. These wide variations in kinetic variables in elderly patients and the need to obtain narrow ranges in serum concentrations required measuring serum concentrations and individually calculating each patient's dosage requirement early in the treatment course. Doing this consistently produced optimal peak and trough serum levels. Ototoxicity did not occur in any of the patients, and nephrotoxicity may have been drug related in 2% of the elderly patients.

Gentamicin pharmacokinetics in 1,640 patients: method for control of serum concentrations

The pharmacokinetics and dosage requirements of gentamicin were studied in 1,640 patients receiving treatment for gram-negative infections. A wide interpatient variation in the kinetic parameters of the drug occurred in all patients and in patients who had normal serum creatinine or normal creatinine clearance. The half-life ranged from 0.4 to 32.7 h in 331 patients who had normal creatinine clearance. The factors related to the elimination rate constant were creatinine clearance, age, distribution volume, weight, gender, and hematocrit. The daily dose necessary to obtain therapeutic serum concentrations ranged from 0.5 to 25.8 mg/kg in patients with normal serum creatinine and from 0.7 to 25.8 mg/kg in patients with normal creatinine clearance. In 13 patients (0.9%), a significant change in base-line serum creatinine (greater than or equal to 0.5 mg/dl) occurred during or after treatment, which may have been gentamicin-associated toxicity. Overt cochlear or vestibular toxicity did not occur in these patients. The method of individualizing dosage regimens provided a clinically useful means of rapidly attaining therapeutic peak and trough serum concentrations.

Increased burn patient survival with individualized dosages of gentamicin

The clinical effect of measuring serum gentamicin concentrations and individualizing each patient's dosage regimen was determined 105 burn patients with severe gram-negative sepsis. Thirty-nine patients (conventionally dosed group) received the recommended dosage regimen of 3 to 5 mg/kg/day from 1972 to 1974. From 1974 to 1976, serum concentrations were measured in 66 patients (individually dosed group), and each patient's dose was individually calculated to obtain therapeutic serum concentrations. All patients had normal renal function prior to initiation of gentamicin therapy. For each group, 16 independent variables were compared that may have influenced treatment response. The patients in the individually dosed group required an average dose of 7.4 mg/kg/day to achieve therapeutic concentrations, compared to the average dose of 4.4 mg/kg/day for the patients receiving conventional doses (P less than 0.001). An abrupt increase in patient survival occurred with the implementation of individualized regimens. Patient survival rates for the entire hospital course were 33% and 64% for the conventionally dosed and individually dosed groups, respectively (P less than 0.005). Survival rates for the first septic episode were 51.3% and 86.4%, respectively (P less than 0.001). Individualized gentamicin regimens, age, percent burn, and sex were the statistically significant variables related to patient survival for the first episode of sepsis. Age, percent burn, individualized dosing, complications during hospitalization, and a positive blood culture were significant factors related to patient survival for the entire hospital course. These data confirm the need for measuring serum gentamicin concentrations and adjusting dosages to ensure therapeutic levels and maximal efficacy of gentamicin in burn patients.

Increased gentamicin dosage requirements: rapid elimination in 249 gynecology patients

Wide interpatient variations were demonstrated in gentamicin elimination rate and dosage requirements for 249 gynecology patients with normal renal function. These variations combined with the need to obtain narrow ranges in serum levels necessitated measuring serum concentrations and individually calculating each patient's dose and dosing interval. Optimal peak and trough serum concentrations were reliably and rapidly achieved by means of this method. Required dosage regimens ranged from 1.9 to 14.0 mg/kg/day. Ototoxicity and nephrotoxicity did not occur in these patients. These results further emphasize the need to measure serum concentrations and make necessary dosage adjustments to ensure therapeutic levels. However, because of the wide interpatient variation, these increased dosages are not routinely suggested without previously measuring serum concentrations and calculating each patient's dosage regimen.

Rapid gentamicin elimination in obstetric patients

Wide interpatient variation in gentamicin elimination rates and dosage requirements was demonstrated in 67 obstetric patients with normal serum creatinine levels. A poor correlation occurred between the elimination rate of gentamicin and creatinine clearance (r = .23). A higher correlation was found between the drug's elimination rate and distribution volume (r = -.62), which suggests that the changing fluid status associated with pregnancy affects the kinetic parameters of gentamicin. Gentamicin dosage regimens were systematically calculated for each patient from serum concentration-time data to obtain desired serum levels. These individualized regimens demonstrated considerable variability, ranging from 3.0 to 11.6 mg/kg/day. Clinical ototoxicity and nephrotoxicity were not observed. Because of the wide interpatient variation, these increased dosages are not routinely suggested unless serum concentrations are previously measured and each patient's regimen is calculated. These results emphasize the need to measure serum concentrations and make necessary dosage adjustments to ensure therapeutic levels in obstetric patients.

Systematically individualizing tobramycin dosage regimens

Tobramycin dosage regimens were individually calculated from serum concentration-time data in 64 patients. Tobramycin pharmacokinetic parameters and dosage requirements demonstrated wide interpatient variation. The tobramycin half-life varied from 0.5 to 8.6 hours in patients with normal serum creatinines. The mean (+/- S.D.) distribution volume was 0.22 (+/- 0.09) liter/kg for all patients. Dosage requirements were higher for the younger patients, however, considerable variability existed within age groups. In patients with normal serum creatinines, an 8-hour dosing interval was optimal in only 17 of the 46 patients. A multiple regression model using age, weight, and creatinine clearance could explain only 44.2% of the variance in tobramycin clearance. Measured steady-state peak and trough concentrations compared favorably with desired peak and trough concentrations. The mean (+/- S.D.) desired peak was 7.2 (+/- 1.8) microgram/ml, and the mean (+/- S.D.) measured peak was 7.1 (+/- 2.0) microgram/ml. The mean (+/- S.D.) desired trough was 1.1 (+/- 0.9) microgram/ml, and the mean (+/- S.D.) measured trough was 1.3 (+/- 0.8) microgram/ml. Many patients required dosage regimens exceeding those commonly recommended; however, no cases of ototoxicity or nephrotoxicity were encountered. This model proved successful in calculating dosage regimens of tobramycin to obtain optimal serum concentrations.

The management of human bite injuries of the hand

Three hundred twenty-seven bite injuries of the hand were reviewed for incidence of infectious complications. A policy to hospitalize all patients with human bite injuries was maintained, but noncompliance was high. Patients with uninfected or superficially infected bites (131) were hospitalized and treated with parenteral penicillin, cephalosporins, or clindamycin (mean duration, 45 hours). Among the 62 patients not lost to followup three minor septic complications occurred. Of similar patients not hospitalized (134), only two thirds received antibiotic therapy but no complications were observed. These data suggest that human bite hand infections can be averted and that established superficial infections can be successfully treated with outpatient antibiotic therapy. Of the 62 patients with moderately to severely infected human bites, 77% were injured by striking an opponent; 52% suffered injury over metacarpophalangeal joints. The mean delay in seeking medical attention was 2 1/2 days, compared to 1/2 day in the less severely infected group. Of the patients with more seriously infected bites, 94% received parenteral antibiotic therapy. Of 30 patients with known outcome in the latter group 27% suffered complications (stiffness; recurrent infection; other infectious complication), confirming the high morbidity of established deep hand infections secondary to human bites.

Ecthyma gangrenosum: survival with individualized antibiotic therapy

Five burn patients with ecthyma gangrenosum were treated with gentamicin sulfate in an individualized aminoglycoside regimen. Dosages greater than the currently recommended 3 to 5 mg/kg/day were necessary and ranged from 15 to 30 mg/kg/day. These increased dosages cannot be used routinely but only as serum level data indicate the need. Four of the five patients survived their course of ecthyma gangrenosum. The single fatality received a much smaller dosage of gentamicin as compared with the other four patients. No ototoxic or nephrotoxic reactions were noted in any of the patients.

Antacid therapy and nutritional supplementation in the prevention of Curling's ulcer

The incidence of clinically evident Curling's ulcer among 109 potentially salvageable severely burned patients was reviewed. These patients, who had greater than a 40 per cent body surface area burn, received one of these three treatment regimens: antacids hourly until autografting was complete, antacids hourly during the early postburn period followed by nutritional supplementation with Vivonex until autografting was complete or no antacids during the early postburn period but subsequent nutritional supplementation with Vivonex until autografting was complete. Clinically evident Curling's ulcer occurred in three patients. This incidence approximates the lowest reported among severely burned patients treated prophylactically with acid-reducing regimens to minimize clinically evident Curling's ulcer. In addition to its protective effect on Curling's ulcer, Vivonex, when used in combination with a high protein, high caloric diet, meets the caloric needs of the severely burned patient. Probably, Vivonex, which has a pH range of 4.5 to 5.4 protects against clinically evident Curling's ulcer by a dilutional alkalinization of gastric secretion.

The transparent face mask

Fabrication of an accurate transparent mask for total contact pressure to the healed burned face proved helpful in controlling scarring. Wearing the mask for 20 hours daily, secured by elastic straps giving 35-mmHG pressure to the scar, can prevent the original facial contours from being distorted by contracting scar tissue.

The necessity of increased doses of amikacin in burn patients

Extended periods (6 to 9 hours) of subtherapeutic serum amikacin levels were observed in five burn patients receiving the recommended intravenous dose of 7.5 mg/kg every 12 hours. Kinetic studies revealed an unusually short half-life, especially in younger patients. This more rapid elimination necessitated a shorter dosing interval (every 6 hours), resulting in an increased daily dose (30 mg/kg/day). In this study of 10 patients with normal renal function, an intravenous dosage regimen of 7.5 mg/kg every 6 hours resulted in therapeutic peak concentrations and shortened intervals of subtherapeutic serum concentrations. A transient episode of tinnitus without cochlear damage occurred in one patient after the first dose. Neither ototoxicity nor nephrotoxicity occurred in any of the patients. Because of interpatient variability in amikacin elimination, frequent monitoring of serum levels with necessary dosage changes is imperative to provide optimal serum concentrations. However, it must be emphasized that these increased dosage regimens of amikacin are not suggested for routine use without previously measuring serum levels.

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.

Correlation of predicted versus measured creatinine clearance values in burn patients

Four methods for predicting creatinine clearance (Ccr) from serum creatinine concentration (Scr) were evaluated in 19 male burn patients with burn wound sepsis. Measured Ccr values were calculated from 24-hour urinary catheter collections. Steady state Scr values were obtained during the same collection interval. Predicted Ccr values were derived from Scr using the methods of Cockcroft and Gault (Method II), Siersbaek-Nielsen, Kampmann and others (Method III) and Jeliffe (Methods I and IV). Wide differences between measured and predicted values were observed but were statistically significant (p less than 0.05) for Method I only. The smallest mean difference (+/-0.02 ml/min/1.73 m2) occurred with Method II measured-predicted data pairs. Method III predicted Ccr values which correlated best with measured values (r=0.770) and showed the least variability (+/-7.6 ml/min/1.73 m2). All methods appeared to overestimate when measured Ccr was less than 60 ml/min/1.73 m2. Use of estimated lean body weights did not improve correlations between predicted and measured Ccr values. While Methods II and III may provide useful initial approximations of Ccr in burn patients, reliance upon predicted Ccr values for dosage modification in burn patients may result in an insufficient reduction in dosage. Whenever possible, dosage regimens for drugs with narrow therapeutic margins should be developed or adjusted using pharmacokinetic values determined in the individual patient.

Brachial artery disruption following closed elbow dislocation

Although elbow dislocation occurs frequently, associated brachial artery injury is rare. Adequate treatment of this injury includes prompt arteriography, reduction of the dislocation, vascular repair, and transarticular fixation of the reduction. A case report and review of the literature are presented.

Granulocyte transfusions for patients with severe thermal burns

Ten severely burned (greater than 50% BSA) pediatric and young adult patients developed 19 episodes of clinical sepsis of four or more days duration. During eight of the 19 septic episodes the patients received granulocyte transfusions (median, four; range, two to seven). Risk variables, types and prevalence of infections, mainly Pseudomonas aeruginosa and antibiotic regimens were similar for all the septic episodes studied. All eight episodes (100%) resolved in the transfused group while eight of 11 (72%) episodes resolved in the nontransfused group. Patients survived four episodes of ecthyma gangrenosum when granulocyte transfusions were used and the single episode in which they were not used was fatal. Granulocyte transfusions may be helpful in severely burned patients with sepsis.

Acute reversible renal failure following jejunoileal bypass for morbid obesity: a clinical and pathological (EM) study of a case

A patient who underwent jejunoileal bypass for morbid obesity developed servere renal failure associated with hyperoxaluria and renal oxalosis. Renal function improved and oxalate excretion decreased following hemodialysis and restoration of gastrointestinal continuity.

The salvageability of patients with post-traumatic rupture of the descending thoracic aorta in a primary trauma center

If uniform early diagnosis is accomplished, two thirds of patients with rupture of the proximal descending aorta seen at a primary trauma treatment center are potentially salvageable. Currently the survival rate is only one half of this optimum figure (31%). One third of 39 patients with acute rupture of the proximal descending thoracic aorta studied had lethal concomitant injuries and were unsalvageable. Twenty-six patients were potentially salvageable; twelve (46%) survived. Eight potential survivors (31%) died because their aortic rupture was not diagnosed or because it was not promptly diagnosed. Eighteen of the potentially salvageable patients (69%) underwent aortic repair; two thirds survived. Aortic rupture was uniformly diagnosed earlier in the more critically injured patients and thus they underwent aortic repair earlier. One half of the 12 patients in whom thoracotomy was instituted within 6 hours of admission survived; six patients who underwent aortic repair more than 6 hours after admission survived.

T lymphocyte rosette formation after major burns

The ability of lymphocytes to form rosettes with sheep erythrocytes was studied in the acute burn period to quantitate T lymphocytes. Seventeen adult patients with burns of greater than 15% body surface area were studied serially and compared to normal controls. The absolute number of total rosette-forming cells (RFC) averaged 1,229.1 +/- 92.8/cu mm (SEM) for controls. In patients, a comspicuous decrease in absolute number of total RFC occurred at days 3 to 5 postburn (578.0 +/- 144.2/cu mm) (P less than .001) and during days 6 to 10 (799.8 +/- 106.1/cu mm) (P less than .01). Similarly, the percentage total RFC in patients at days 6 to 10 (48.9% +/- 3.3%) was significantly lower than controls (73.9% +/- 0.7%) (P less than .01). The decrease in total RFC did not correlate with the total lymphocyte count or the cortisol level. These findings suggest that T lymphocytes are decreased or have altered rosette-forming ability in the early postburn period and are in accordance with other reports of impaired cellular immunity following burns.

The natural history of electrical injury

The natural history of electrical injury, exclusive of electrical flash burns, was determined in 64 patients. These patients sustained relatively small burns (x=11%); only nine patients (14%) had burns greater than 25%. Forty-six patients suffered 114 major complications. EKG abnormalities occurred in 36%, including major cardiac arrhythmias in ten patients. One-fourth of the patients developed neurologic sequelae (CNS-8, peripheral-8). Electrical vascular injury with subsequent arterial occlusion was responsible for many of the major amputations. Nineteen patients required 32 amputations (digits-17, hand-1, foot-2, leg-3, arm-9). Early patient referral and vigorous fluid resuscitation minimized renal failure (1.5%) and mortality (3.1%). Early fasciotomy and vigorous debridement appeared to decrease wound sepsis (8%), but apparently had little if any effect on major limb salvage. The unsolved problems of electrical injury, namely neurological and vascular sequelae, are major contributors to the high morbidity of electrical injury.

Kinetic model for gentamicin dosing with the use of individual patient parameters

Multiple-infusion dosing regimens for gentamicin were established for 84 patients with the use of individually calculated values of elimination kinetic parameters. Serum level-time data obtained after a single infusion were used to determine the patient's gentamicin half-life (t 1/2) and distribution volume. Patients with serum creatinine (Cr) less than 1.2 mg per 100 ml had t 1/2 (mean, 2.25 hr) and total body clearances (mean, 0.082 L/hr/kg) significantly different from those with Cr greater than or equal to 1.2 mg/100 ml (means, 5.3 and 0.039, respectively). Distribution volumes were not significantly different (means, 0.22 and 0.21 L/kg, respectively). Calculations of dosing intervals and infusion rates, based on each patient's kinetic parameters and desired steady-state peaks and nadirs, assumed a one-compartment model with first-order elimination and 1-hr constant-rate input at fixed intervals. Follow-up steady-state peak and nadir levels were measured in 63 of the regimens. Differences between predicted and measured peak levels averaged --0.05 mug/ml with 60% of the measured values falling within 1 mug/ml of that predicted. Predicted-measured nadir differences averaged --0.62 mug/ml (significantly different from zero) indicating slight bias in the model. Fifty-six percent of these nadirs were within 1 mug/ml of that predicted.

Increased dosage requirements of gentamicin in burn patients

In 14 burn patients treated for serious Gram-negative infections, the use of the previously recommended gentamicin dose of 5 mg/kg/day was found to result in subtherapeutic serum concentrations (peak concentration less than 4 mg/L). The gentamicin half-life was found to be unusually short especially in the younger burn patients. Because of this shorter half-life the dosage interval was decreased to 4 hours to prevent extended periods of subtherapeutic serum concentrations. In addition, the daily dose of gentamicin was increased to achieve therapeutic peak concentration. Individualizing each patient's gentamicin regimen was thought to be instrumental in the favorable response of two patients with Pseudomonas ecthyma gangrenosum. The results of this study would strongly support the measurement of serum gentamicin levels in all burn patients with life-threatening infection. The gentamicin dosage regimen should then be individualized for each patient to provide optimal peak concentrations. In addition, patients demonstrating a short drug half-life may require a decreased dosage interval to prevent prolonged periods of sub-therapeutic concentrations.

The emergency management of trauma

For effective care, the severely injured patient may require the cooperative effort of many physicians and paramedical personnel. In the individual with isolated maxillofacial injury, adequate management may be provided by one or several specialists. In any event, there should be a plan for emergency, semiurgent, and delayed treatment. It is also important for each individual caring for the patient to understand and appreciate the problems within and outside his area of expertise. There is a logical progression of evaluation, with particular attention to the more severe and significant area of trauma. Hemmorrhage, shock, and airway problems take priority. Often the definitive treatment, from a cosmetic and functional standpoint, is delayed.