The effects of pressure control versus volume control assisted ventilation on patient work of breathing in acute lung injury and acute respiratory distress syndrome.

BACKGROUND: Patient work of breathing (WOB) during assisted ventilation is reduced when inspiratory flow (V(I)) from the ventilator exceeds patient flow demand. Patients in acute respiratory failure often have unstable breathing patterns and their requirements for V(I) may change from breath to breath. Volume control ventilation (VCV) traditionally incorporates a pre-set ventilator V(I) that remains constant even under conditions of changing patient flow demand. In contrast, pressure control ventilation (PCV) incorporates a variable decelerating flow wave form with a high ventilator V(I) as inspiration commences. We compared the effects of flow patterns on assisted WOB during VCV and PCV. METHODS: WOB was measured with a BICORE CP-100 monitor (incorporating a Campbell Diagram) in a prospective, randomized cross-over study of 18 mechanically ventilated adult patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Tidal volume, inspiratory time, and mean ventilator V(I) were constant in each mode. RESULTS: At comparable levels of respiratory drive and minute ventilation, patient WOB was significantly lower with PCV than with VCV (0.59 +/- 0.42 J/L vs 0.70 +/- 0.58 J/L, respectively, p < 0.05). Ventilator peak V(I) was significantly higher with PCV than with VCV (103.2 +/- 22.8 L/min vs 43.8 L/min, respectively, p < 0.01). CONCLUSIONS: In the setting of ALI and ARDS, PCV significantly reduced patient WOB relative to VCV. The decrease in patient WOB was attributed to the higher ventilator peak V(I) of PCV.

Initial severity of metabolic acidosis predicts the development of acute lung injury in severely traumatized patients.

OBJECTIVES: First, to determine whether the severity of shock, as measured by systemic hypotension and metabolic acidosis, is significantly associated with a higher risk of acute lung injury in patients with severe trauma. Second, to determine whether the volumes of blood and crystalloid solutions administered in the early posttrauma period are independent risk factors for acute lung injury in severely traumatized patients. DESIGN: Prospective observational study. SETTING: Level I urban trauma center in a university hospital. PATIENTS: A total of 102 severely injured, mechanically ventilated trauma patients with an Injury Severity Score > or =16 and aged between 18 and 75 yrs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Initial clinical and laboratory data were collected in the emergency department, and on a daily basis thereafter during the patient's intensive care unit stay. Of the 102 severely injured patients enrolled, 42 developed acute lung injury (41%) and 60 did not (59%). A total of 93% of the trauma patients who developed acute lung injury during the 17-month study period were included in the study. Initial base deficit was significantly lower in patients who developed acute lung injury than in those who did not (-8.8+/-4.5 vs. -5.6+/-5.1, p<.01). The difference in systolic blood pressure between the two groups was not significant. CONCLUSIONS: In this group of severely injured trauma patients, the degree of metabolic acidosis at the time of admission identified those patients with the highest probability of developing acute lung injury. In addition, the volume of crystalloid solution administered during the first 24 hrs was significantly greater in patients who later developed acute lung injury. Finally, there was a significantly higher morbidity in patients who developed acute lung injury, whereas mortality did not differ between the two groups.

Leukocytosis and free fluid are important indicators of isolated intestinal injury after blunt trauma.

BACKGROUND: The detection of isolated intestinal injuries after blunt trauma can be difficult because of subtle signs and symptoms, often leading to delayed diagnosis. We hypothesized that specific clinical indicators could be identified to assist in the diagnosis of these injuries. METHODS: Medical records of all patients with such injuries from 1988 to 1996 were reviewed. The patients were stratified into those operated on within 6 hours of presentation (apparent injury) and those operated on after 6 hours (occult injury), and the data were compared. RESULTS: Forty-six patients with isolated intestinal injuries were identified. There were no differences in the rate of peritonitis or free fluid on abdominal computed tomography, blood loss, intraoperative findings, or morbidity and mortality between groups. Leukocytosis (sensitivity, 84.8%; specificity, 55.2%; p = 0.01) and free fluid on computed tomography were frequently present, however, and their significance was underappreciated in the occult injury group. CONCLUSION: After blunt abdominal trauma in patients without obvious indications for invasive evaluation of the abdomen (e.g., peritoneal lavage, laparoscopy, laparotomy), leukocytosis can indicate an intestinal injury. Additionally, unexplained free fluid on abdominal computed tomography must be aggressively evaluated.

Trauma experience of Navy surgeons: assessment and commentary.

Numerous reports have suggested that surgical readiness during Operation Desert Storm was poor. We surveyed active duty Navy surgeons to assess current trauma experience and capability. A survey concerning trauma and critical care experience, as well as self-rating of skills, was mailed to all active duty surgeons (n = 185) in 1993. The response rate was 79% (146/185). A high turnover rate of surgeons was indicated by: (1) 51% (75/146) of surgeons had less than 3 years of experience following residency; and (2) only 42% (61/146) had served in the Gulf War. Only 12% of active duty surgeons (18/146) were involved in trauma care. Only 10% (14/146) had performed more than 20 operations for trauma in the preceding 1 years, and 85% (124/146) had performed fewer than 10 operations. In the preceding 5 years, 84% (122/146) had performed fewer than 100 operations for trauma, and 42% (61/146) had performed none. Critical care experience ranged from 0 to 20 patients per month (mean = 3). Despite limited recent experience, 84% (123/146) of respondents rated their trauma skills as adequate (n = 43), good (n = 49), or excellent (n = 31). We conclude that most Navy surgeons have minimal recent experience in trauma care. A high rate of turnover mandates training strategies that provide an ongoing exposure to injured patients. This could be accomplished by designating military hospitals as trauma centers or by placing military surgeons in civilian trauma centers.

Therapeutic laparoscopy in trauma.

PURPOSE: To assess the therapeutic potential of emergent laparoscopy in the trauma setting, a retrospective review was performed in a busy urban trauma center. PATIENTS AND METHODS: Between December 1991 and October 1993, 133 hemodynamically stable patients with suspected abdominal injury were evaluated laparoscopically. All laparoscopic procedures were performed in the operating room under general anesthesia. Mechanism of injury was stab wound (58), gunshot wound (57), and blunt trauma (18). No significant injuries were found in 72 patients (54%), and these patients received no further treatment. On the basis of laparoscopic findings, 52 patients underwent formal exploratory laparotomy. Surgical exploration confirmed the presence of significant injuries in 44 of the 52 patients (85%). Therapeutic laparoscopy was performed in 6 patients (5%) for diaphragm repair (4), gastrotomy repair (1), and splenorrhaphy (1). Additionally, 10 patients underwent laparoscopy-guided blood salvage for autotransfusion during laparoscopic evaluation of blunt trauma. Three small-bowel enterotomies were repaired during minilaparotomy. RESULTS: No significant injuries were missed as a result of our use of laparoscopy in trauma assessment. Complications--trocar enterotomy, trocar laceration of the inferior epigastric artery, and transient hypotension--occurred in 3 patients secondary to the use of laparoscopy. CONCLUSIONS: Trauma laparoscopy is a safe method for the evaluation of selected patients with abdominal trauma and can reduce the number of negative and nontherapeutic trauma laparotomies performed. Limited therapeutic intervention is possible in a small number of patients.

Duplex scanning replaces arteriography and operative exploration in the diagnosis of potential cervical vascular injury.

BACKGROUND: The pursuit of a diagnosis is more aggressive in suspected cervical vascular injury than in extremity vascular proximity injury, since the complications of missing the neck injury may result in irreversible neurologic damage. Most institutions use arteriography and operative exploration, but these modalities identify only 10% of cervical vascular traumas. While duplex scanning is the screening test of choice for carotid occlusive disease, few published reports have described experience with this modality in cervical vascular trauma. PATIENTS AND METHODS: To determine if duplex scanning can replace arteriography or operative exploration as the initial screening modality in the assessment of potential cervical vascular trauma, we performed a prospective evaluation in two parts. First, we used duplex scanning and cervical arteriography, concomitantly, to rule out injury in 15 patients. We then used duplex scanning alone in 85 patients, reserving arteriography for cases in which the scan revealed an arterial injury. RESULTS: Duplex scans and arteriography and operation diagnosed cervical vascular trauma equally well. Eight injuries were identified in all areas of the cervical arterial tree. No duplex scans have been falsely negative or falsely positive. Use of duplex scans instead of arteriography saved $1,252 per case. CONCLUSIONS: Duplex scanning detects cervical vascular injuries as effectively as arteriography or operation, and is faster and less expensive. This approach expands the utility of diagnostic ultrasound in the evaluation of trauma patients. It has become the procedure of choice for diagnosing cervical vascular trauma at our institution.

Limited utility of emergency department thoracotomy.

To assess the therapeutic role and cost effectiveness of resuscitative thoracotomy in an urban trauma center, a retrospective review of thoracotomies (n = 273) performed in a trauma unit between 1986 and 1992 was undertaken. A total of 252 thoracotomies were performed for penetrating injuries (92%), and 21 (8%) were performed for blunt trauma. Ten neurologically intact survivors (3.7%) were identified. Mechanisms of injury in survivors were stab wound (n = 6) and gunshot wound (n = 4). There were no neurologically intact survivors when resuscitative thoracotomy was done for blunt trauma. All survivors sustained penetrating truncal injuries; isolated thoracic injuries existed in six patients, while four patients presented with both thoracic and abdominal wounds. All survivors had signs of life either in the field or in the trauma unit. Of the 242 non-survivors who had sustained penetrating trauma, only 49 had signs of life either in the field or upon arrival at the trauma unit. In this group, survival was 17 per cent. Revised Trauma Scores, calculated in the trauma unit, failed to differentiate between survivors and nonsurvivors. In 1992, the average hospital charge for resuscitative thoracotomy was $3413 per patient. Total charges during the study period for resuscitative thoracotomy were approximately $932,000. This represents an expenditure of $93,000 per successful thoracotomy. If thoracotomy was limited to patients sustaining penetrating trauma who demonstrated signs of life, total charges would be approximately $201,367, representing an expenditure of $20,137 per successful thoracotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Preliminary report on videothoracoscopy in the evaluation and treatment of thoracic injury.

A prospective trial of videothoracoscopy was conducted at an urban trauma center between February 1992 and February 1993 to determine the efficiency of this less invasive method of evaluation and treatment. Twenty-four consecutive patients with chest trauma (penetrating, n = 22; blunt, n = 2) were examined thoracoscopically for clotted hemothorax that otherwise would have been treated with thoracotomy (n = 9), suspected diaphragmatic injury (n = 10), and continued bleeding (n = 5). To ensure maximal exposure, general anesthesia with a double-lumen endotracheal tube was used in each patient. Clotted hemothorax was successfully evacuated in eight of nine patients (89%). Diaphragmatic laceration was suspected in 10 patients (2 abnormal chest radiographs, 8 proximity penetrating wounds) and confirmed thoracoscopically in 5. In four patients, diaphragmatic lacerations were successfully repaired with thoracoscopic techniques. Five patients underwent thoracoscopy for continued hemorrhage (greater than 1,500 mL per 24 hours) after tube thoracostomy. Intercostal artery injury was confirmed in all patients, and diathermy provided hemostasis in three patients without thoracotomy. No complications occurred. These data suggest the following: (1) Videothoracoscopy is an accurate, safe, and minimally invasive method for the assessment of diaphragmatic injuries, control of continued chest wall bleeding, and early evacuation of clotted hemothorax. (2) This technique should be used more frequently in patients with thoracic trauma. (3) Technical advances may expand the therapeutic role of thoracoscopy.

The success of duplex ultrasonographic scanning in diagnosis of extremity vascular proximity trauma.

OBJECTIVE: To determine if duplex ultrasonographic scanning is diagnostically equivalent to arteriography and/or operative exploration in the diagnosis of extremity vascular proximity trauma. DESIGN: A prospective evaluation comparing duplex scanning with arteriography or operative exploration in 50 patients. Subsequently, duplex scanning was used alone for 175 extremity vascular proximity injuries, with other diagnostic methods used when injury was indicated on the duplex scan. SETTING: A busy urban trauma center. PATIENTS: Consecutive sample of 200 patients with 225 extremity injuries. SELECTION CRITERIA: Vascular proximity injury or diminished strength of the extremity pulse. MAIN OUTCOME MEASURES: The presence or absence of vascular proximity injury confirmed on angiography and/or operative exploration. RESULTS: Duplex scanning had 100% sensitivity and 100% specificity compared with arteriography and/or operative exploration in the first 50 cases. In the remaining 175 cases of extremity trauma, vascular injuries were diagnosed with duplex scanning alone. Duplex scanning detected 18 injuries, 17 of which were confirmed by correlation with arteriograms and/or operative exploration. One false-positive result--spasm of the superficial femoral artery--was found on arteriography. Seven unsuspected venous injuries were also diagnosed. CONCLUSIONS: Duplex scanning is a noninvasive, safe, effective method for the initial evaluation of potential extremity vascular proximity injury. It has replaced arteriography in the initial diagnosis of extremity vascular proximity trauma by our trauma service.

Gasless laparoscopy and conventional instruments. The next phase of minimally invasive surgery.

OBJECTIVE: To assess the capability of a retractor system that permits laparoscopic surgery without pneumoperitoneum and to determine if the system facilitates the use of conventional surgical instruments during minimally invasive surgery. DESIGN: Prospective evaluation and data collection with review. SETTING: University-affiliated county hospital. PATIENTS: Twenty-nine male and 29 female subjects evaluated prospectively via 27 trauma-related and 31 elective procedures. METHODS: Fifty-eight laparoscopic procedures were performed between July 1992 and February 1993 with a system consisting of an intra-abdominal fan retractor and an electrically powered mechanical arm using conventional surgical and laparoscopic instruments. RESULTS: Gasless laparoscopy was used in the evaluation of 27 patients with abdominal trauma (11 gunshot wounds, 11 stab wounds, and five blunt injuries). The need for celiotomy was obviated in 20 (74%) of 27 cases. Three enterotomies, two diaphragmatic lacerations, and one gastric perforation were repaired with conventional instruments. Gasless laparoscopic techniques were also used in cholecystectomy (n = 26), diagnostic laparoscopy (n = 3), and appendectomy (n = 2). Exposure similar to that obtained by pneumoperitoneum was obtained in 30 (97%) of 31 cases. One major (trocar tip enterotomy) and two superficial wound infections occurred in this group. The ability to use conventional surgical instruments was advantageous in several cases. CONCLUSIONS: Comparable exposure was achieved in this cohort of patients with gasless laparoscopy. The use of conventional surgical instruments provides an advantage with this technique. Further improvements in abdominal wall lift systems and modification of existing surgical instruments may expand the role of gasless laparoscopy.

Recidivism in an urban trauma center.

The incidence of recurrent injury requiring evaluation and treatment at an urban trauma center was assessed by examination of data from the registry of an urban trauma unit. A subgroup of 342 recidivists sustained 711 traumatic injuries. This represented 6.4% of trauma service activations or consultations. The rates of recurrence in random groups of 100 patients with trauma and 50 patients with traumatic deaths were 5% and 12%, respectively. These rates of recurrent injury are lower than those of several previous reports. Comparison of patients with recurrent episodes of trauma with patients who experience a single episode of trauma revealed significant differences in age, sex distribution, mechanism of injury, and fatal outcomes. Recidivists averaged only 7.9 months between episodes of injury. In patients with recurrent trauma with fatal outcomes, the mean interval between initial injury and death was 18.8 months. Early identification of patients at high risk for recurrence may provide an opportunity for behavior modification.

Overview of trauma registries.

Registry data related to patient volume, flow, severity, resource use, and reimbursement sources provides valuable information to administrative staff for program management and strategic planning activities.