Prone positioning for acute respiratory distress syndrome in the surgical intensive care unit: who, when, and how long?

BACKGROUND: We evaluated the effects of prone positioning (PP) on surgery and trauma patients with acute respiratory distress syndrome (ARDS). METHODS: Patients with ARDS were studied. Exclusion criteria were contraindications to PP. Patients were evaluated in the supine position and after being turned to the PP. After 6 hours, patients were returned to the supine position for 3 hours. One hour after each position change, arterial and mixed venous blood was drawn and analyzed for blood gases and pH, and hemodynamics were measured. RESULTS: Over 20 months, 27 patients met the criteria, and 20 of the patients were entered into the study. On day 1, 18 of 20 patients (90%) responded with an increase in PaO(2) during PP. On day 2, 16 of 17 patients (94%) responded; on day 3, 15 of 16 patients responded (94%); on day 4, 11 of 13 patients responded (85%); on day 5, 8 of 8 patients responded (100%); and on day 6, 4 of 5 patients responded (80%). Pao(2)/Fio(2) and Qs/Qt were significantly improved (P<.05) during PP. There were 91 periods of PP, lasting 10.3+/-1.2 hours. Of 91 changes to PP, 78 changes (86%) resulted in an improvement in Pao(2)/Fio(2) of more than 20%. CONCLUSIONS: PP improves oxygenation in ARDS for 6 days with few complications.

Zone I retroperitoneal hematoma identified by computed tomography scan as an indicator of significant abdominal injury.

OBJECTIVE: All zone I retroperitoneal hematomas (Z1RPHs) identified at laparotomy for blunt trauma traditionally require exploration. The purpose of this study was to correlate patient outcome after blunt abdominal trauma with the presence of Z1RPH diagnosed on admission computed tomography (CT) scan. METHODS: This is a retrospective review of patients with blunt trauma who were admitted to a Level 1 trauma center and who underwent CT scan during a 40-month period. All scans with a traumatic injury were reviewed to identify and grade Z1RPH as mild, moderate, or severe. Patients requiring operative treatment were compared with those who were observed. Statistical analysis was performed with Student's t test and chi-square test, with P < .05 considered significant. RESULTS: Eighty-five (15.5%) of the CT scans were positive for Z1RPH. None of the 50 patients with a mild Z1RPH had their treatment altered. Of the 29 patients with a moderate or severe Z1RPH, 8 required celiotomy. The patients requiring celiotomy had significant elevations of solid viscus score (SVS) (4.9 +/- 1.6 versus 1.8 +/- 0.3), abdominal Abbreviated Injury Scale (3.8 +/- 0.3 versus 2.6 +/- 0.3), and transfusion requirements (13 +/- 4 versus 2 +/- 1). All patients (N = 4) with an SVS >4 required operative treatment. Seventy-two percent of patients with more than 1 intra-abdominal injury required abdominal exploration. CONCLUSIONS: The presence of a moderate or severe Z1RPH and more than 1 intra-abdominal injury or an SVS >4 on admission CT scan is an important radiographic finding. This injury pattern should be considered a contraindication for nonoperative treatment of the associated solid organ injury.

Positive end-expiratory pressure and response to inhaled nitric oxide: changing nonresponders to responders.

BACKGROUND: Inhaled nitric oxide (INO) has been shown to improve oxygenation in two thirds of patients with acute respiratory distress syndrome (ARDS). Failure to respond to INO is multifactorial. We hypothesized that the addition of positive end expiratory pressure (PEEP) might modify the response to INO in patients who had previously failed to respond to INO. METHODS: Patients with ARDS who failed to respond to INO at 1 ppm (PaO2 increase of < 20%) were selected. Each patient underwent a PEEP trial using an improvement in static lung compliance as the end point. One hour after the new PEEP level was reached, hemodynamic and blood gas values were obtained. INO was then reinstituted at 1 ppm, and hemodynamic and blood gas variables were obtained 1 hour later. RESULTS: Six of nine patients demonstrated an increase in PaO2/FIO2 (161 +/- 27 to 186 +/- 29) with a mean increase in PEEP of 3.7 cm H2O. Each patient responding to PEEP further improved PaO2/FIO2 (186 +/- 29 to 223 +/- 36) with INO at 1 ppm. The three patients who failed to improve after the PEEP increase also failed to respond to a second trial of INO. There were no changes in cardiac output or systemic vascular resistance. Pulmonary artery pressures decreased slightly (39 +/- 5 vs 38 +/- 7 vs 35 +/- 9 mm Hg). Pulmonary vascular resistance decreased significantly after reintroduction of INO (298 +/- 131 vs 310 +/- 122 vs 249 +/- 105 dynes/sec/cm-5) in patients who responded positively. CONCLUSIONS: The response of ARDS patients to INO can be improved if optimum alveolar recruitment is achieved by the addition of PEEP. PEEP and INO have a synergistic effect on PaO2/FIO2. Patients who fail to respond to INO may benefit from an optimum PEEP trial.

The risk assessment profile score identifies trauma patients at risk for deep vein thrombosis.

BACKGROUND: The identification of trauma patients at risk for the development of deep venous thrombosis (DVT) at the time of admission remains difficult. The purpose of this study is to validate the risk assessment profile (RAP) score to stratify patients for DVT prophylaxis. METHODS: All patients admitted from November 1998 thru May 1999 were evaluated for enrollment. We prospectively assigned patients as low risk or high risk for DVT using the RAP score. High-risk patients received both pharmacologic and mechanical prophylaxis. Low-risk patients received none. Surveillance duplex Doppler scans were performed each week of hospitalization or if symptoms developed. Hospital charges for prophylaxis were used to determine the savings in the low-risk group. Statistical differences between the risk groups for each factor of the RAP and development of DVT were determined by the chi-squared test, with significance at a probability value of less than .05. RESULTS: There were 102 high-risk (64%) and 58 low-risk (36%) individuals studied. Eleven of the high-risk group (10.8%) experienced the development of DVT (asymptomatic, 64%). None of the low-risk group was diagnosed with DVT. Five of the 16 RAP factors were statistically significant for DVT. Eliminating prophylaxis and Doppler scans in low-risk patients resulted in a total savings of $18,908 in hospital charges. CONCLUSIONS: The RAP score correctly identified trauma patients at increased risk for the development of DVT. Despite prophylaxis, the high-risk group warrants surveillance scans. Withholding prophylaxis in low-risk patients can reduce hospital charges without risk.

Dynamic helical computed tomography scan accurately detects hemorrhage in patients with pelvic fracture.

BACKGROUND: The purpose of this study was to evaluate the use of dynamic helical computed tomography (CT) scan for screening patients with pelvic fractures and hemorrhage requiring angiographic embolization for control of bleeding. METHODS: Patients admitted to the trauma service with pelvic fractures were identified from the trauma registry. Data retrieval included demographics, hemodynamic instability, Injury Severity Score, blood transfusion requirement, length of stay, and mortality. CT scans obtained during the initial evaluation were reviewed for the presence of contrast extravasation and correlated with angiographic findings. Data are reported as mean +/- SEM, with P<.05 considered significant. RESULTS: Seven thousand seven hundred eighty-one patients were admitted from June 1994 to May 1999. A pelvic fracture was diagnosed in 660 (8.5%). Two hundred ninety (44.0%) dynamic helical CT scans were performed, of which 13 (4.5%) identified contrast extravasation. Nine (69%) were hemodynamically unstable and had pelvic arteriography performed. Arterial bleeding was confirmed in all and controlled by embolization. Patients with contrast extravasation had significantly greater Injury Severity Score, blood transfusion requirement and length of stay. Sensitivity, specificity, and accuracy of CT scan for identifying patients requiring embolization were 90.0%, 98.6%, and 98.3%, respectively. CONCLUSIONS: Early use of dynamic helical CT scanning in the multiply injured patient with a pelvic fracture accurately identifies the need for emergent angiographic embolization.

Penetrating injuries of the abdominal aorta.

The charts of 56 consecutive patients with penetrating injuries to the abdominal aorta were reviewed in an attempt to identify prognostic factors. Mechanism of injury was gunshot wound (GSW), 82 per cent (.22 cal: 15.2%; greater than .38 cal: 84.8%); shotgun wound (SGW), 5 per cent; and stab wound (SW), 13 per cent. Overall mortality was 73 per cent, with GSW 78 per cent (.22 cal: 0%; greater than .38 cal: 92%), 67 per cent with SGW, and 43 per cent with SW. Average initial systolic blood pressure (ISBP) was 53 (0-130); 87 (0-120) in survivors; and 40 (0-130) in nonsurvivors (NS). Eighteen patients (32%) had no ISBP, with one survivor. Thirty (54%) patients had ISBP less than 70, with three survivors. Six Emergency Department (ED) thoracotomies were performed, with five patients surviving to reach the operating room (OR), and none surviving long-term. Ten patients died in the ED, 18 during surgical intervention, six within 24 hr, and seven greater than 24 hr postop. Average time from injury to OR was 75 minutes, with 122 minutes in survivors, and 53 minutes in nonsurvivors (P less than 0.05); 49 minutes in those dying in the OR; and 58 minutes in those surviving the OR but dying postop (NS). At surgery, six patients had thoracotomy before celiotomy for control of the thoracic aorta, with three surviving the OR and two surviving long-term. Survivors had 2.53 associated injuries; nonsurvivors had 2.89 (NS). No significant difference was noted in number or location of associated injuries between survivors and nonsurvivors.(ABSTRACT TRUNCATED AT 250 WORDS)

Dehiscence with evisceration: a rare complication of diagnostic peritoneal lavage.

Diagnostic peritoneal lavage (DPL) is a well-established procedure for evaluating the patient suspected of having intraabdominal injury secondary to blunt abdominal trauma. Its accuracy and safety have been clearly documented; however, the procedure does have the potential for morbidity. This paper reports on the occurrence of a rare complication, dehiscence with evisceration, and reviews the literature regarding complications of DPL.

Thoracoscopy for trauma.

Thoracoscopy is currently undergoing a revival in the surgical world. As the role of thoracoscopy increases in the general thoracic surgery arena, the indications for the technique in the care of trauma patients is also expanding. Trauma surgeons are investigating both diagnostic and therapeutic indications. Penetrating thoracoabdominal trauma is a proven indication to evaluate the diaphragm for possible violation. Investigation of thoracic hemorrhage with identification of bleeding sites, evacuation of hemothorax, and control of ongoing blood loss have all been reported successfully via the thoracoscope. Recent reports have sited isolated patients were diaphragmatic repair has been accomplished with endoscopic techniques. Other indications await the improvement of techniques and instruments, and the imagination of future surgeons.

Repair of penetrating cardiac injury using skin staples.

Cardiac stapling is a highly effective technique in the management of hemorrhage from penetrating cardiac injuries. It may allow the salvage of patients with multiple cardiac lacerations who would not otherwise survive following standard suture techniques for repair. Cardiac stapling is probably not indicated in complex injury cases such as those from gunshot, and the trauma surgeon must use judgment in applying the staple technique, though its use for cardiography in the ED and the OR will minimize the risk of contamination of personnel from a needle stick from the repair portion of the surgical procedure. Staplers are readily available, easy to use and safe to surgical personnel, and they provide rapid and effective hemostasis.

Synchronized independent lung ventilation in the management of pediatric unilateral pulmonary contusion: case report.

Utilizing a double-lumen endobronchial tube, synchronized independent lung ventilation (SILV) was successfully employed to manage severe unilateral pulmonary contusion in a 6-year old trauma patient. This appears to represent the youngest reported patient in whom this technique has been utilized. Early institution of this treatment modality may substantially increase survival.

Percutaneous transtracheal catheter ventilation (PTCV) in complete airway obstruction--a canine model.

Percutaneous transtracheal catheter ventilation (PTCV) may be used as an alternative airway when contraindications to endotracheal intubation exist. A canine model tested the efficacy of low-flow oxygen delivery, coupled with commonly available intravenous catheters, for PTCV in a large animal model. Previous studies at this institution demonstrated the feasibility of this technique in a small animal model (feline). Eighteen mongrel dogs were anesthetized, intubated, and ventilated for 30 min with a volume ventilator. The endotracheal tube was then removed, the trachea cross-clamped, and PTCV was instituted and continued for 60 minutes. Arterial blood gas analysis was performed every 5-15 min during the experimental period. Oxygen flow rates of 3, 5, and 7 L/min were paired with catheter sizes of 10 and 12 gauge (g) creating six experimental groups (three animals in each group). Data demonstrate that PTCV provided adequate oxygenation (pO2 greater than 450 mm Hg) and ventilation (pCO2 less than 85 mm Hg) with flow rates of 5 and 7 L/min with both catheter sizes. Satisfactory oxygenation (pO2 greater than 250 mm Hg) could be obtained with the 3 L/min flow rate with both catheter sizes, but ventilation was inadequate (PCO2 greater than 200 mm Hg). Using readily available materials and low-flow oxygen rates this PTCV technique was shown to be safe and effective in oxygenating and ventilating this canine model with complete airway obstruction.

Computed tomography versus diagnostic peritoneal lavage: usefulness in immediate diagnosis of blunt abdominal trauma.

A prospective study was undertaken to compare diagnostic peritoneal lavage with computed tomography in the evaluation of blunt abdominal trauma. Acutely injured patients meeting the advanced trauma life support criteria for lavage were first studied with computed tomography followed by diagnostic peritoneal lavage. Patients underwent exploratory celiotomy for positive results of either study. Computed tomography was read initially by the radiology resident and then by the trauma fellow or senior surgery resident or both. A second interpretation was made by senior radiology staff. Analyses included sensitivity, specificity, false-negative, false-positive, predictive value of positive and negative tests, and accuracy for lavage and each tomography interpretation. Lavage was found to be more accurate than computed tomography in the immediate diagnosis of blunt abdominal trauma and remains the diagnostic test of choice at our institution. Caution is advised in using computed tomography as the primary diagnostic technique until the reliability is demonstrated at any particular institution.

Intrahepatic absorbable fine mesh packing of hepatic injuries: preliminary clinical report.

A previous report from the authors' institution reported the effectiveness of hepatic packing with absorbable fine mesh (AFMP) for the control of hemorrhage in an animal model with an otherwise lethal hepatic injury. The technique has subsequently been applied to 12 abdominal trauma patients with hemodynamic instability and actively hemorrhaging hepatic injuries. Two patients expired in the operating room owing to uncontrolled hemorrhage from hepatic and associated injuries for a mortality of 16.7%. AFMP was successful in controlling hemorrhage in the remaining 10 patients. Hepatic injuries ranged from grade II to grade V, and all were actively hemorrhaging at the time of exploration. None of the surviving 10 patients experienced early or late recurrent bleeding attributable to the hepatic injuries, and there were no intraabdominal abscesses or late deaths. Liver function studies returned to normal prior to discharge in all surviving patients. Follow-up included serial computed tomographic scans, which demonstrated fibrosis incorporating the mesh packing. Complete resolution of injury and mesh appears to proceed over approximately a 6-month period. AFMP is a safe, effective method for controlling hepatic hemorrhage. It is easy to perform in the operating room, offers an excellent matrix for hemostasis, provides tamponade of bleeding sites, and does not require reoperation for removal of packing material, as is necessary with conventional, nonabsorbable packing techniques.

Adrenergic antagonists reduce lactic acidosis in response to hemorrhagic shock.

BACKGROUND: Hemorrhagic shock is associated with lactic acidosis and increased plasma catecholamines. Skeletal muscle increases lactate production under aerobic conditions in response to epinephrine, and this effect is blocked by ouabain, a specific inhibitor of the cell membrane Na+/K+ pump. In this study, we tested whether adrenergic antagonists can block lactate production during shock. METHODS: Male Sprague-Dawley rats (250-300 g) were pretreated with phenoxybenzamine (2 mg/kg, i.v.) and/or propranolol (0.5 mg/kg, i.p.) before hemorrhaging to a mean arterial pressure of 40 mm Hg for 1 hour. Skeletal muscle perfusion, plasma lactate, and catecholamines were measured at baseline, 55 minutes after shock, and 1 hour after resuscitation. In a separate study, extensor digitorum longus and soleus muscles were incubated in Krebs buffer (95:5, O2:CO2) with 10 mmol/L glucose. One of each muscle pair was incubated in the absence or presence of epinephrine and of one or both adrenergic blockers. Medium lactate concentration was then measured. RESULTS: The combination of alpha- and beta-blockers significantly reduced plasma lactate levels during hemorrhage. In contrast, beta-blockade alone was associated with a significant increase in plasma lactate and epinephrine. None of the blockers altered tissue perfusion. Epinephrine stimulation of muscle lactate production in vitro was completely blocked by propranolol. CONCLUSION: Epinephrine release in response to hypotension is a primary stimulus for muscle lactate production in this model of hemorrhagic shock. Hypoxia alone does not explain the increased lactate levels because tissue perfusion was not altered by the adrenergic antagonists. These observations challenge the rationale behind lactate clearance as an end point for resuscitation after hemorrhagic shock.

Primary repair vs. colostomy for the treatment of penetrating colon injuries.

The charts of 81 consecutive patients with penetrating colonic trauma were reviewed. Sixty-five patients were considered for evaluation. Penetrating abdominal trauma index, associated injuries, length of operative procedure, wounding agent, length of hospital stay, method of treatment, and septic complications were evaluated. Twenty-eight patients were treated with colostomy at the site of injury: five with diverting colostomy proximal to repair, 30 with primary repair (either single or multiple injuries), and two with exteriorization and early drop back. Overall septic morbidity was 15 of 65 (23 percent) patients. No statistically significant difference was found in morbidity between colostomy, 9 of 33 (27 percent), and primary repair, 6 of 30 (20 percent). The two patients with exteriorized repairs had no morbidity. No deaths were reported among the 65 patients studied. Thirty-two of the 33 (97 percent) colostomies were later closed with morbidity in 7 of 32 (22 percent). The mean length of stay for primary repair patients was 10.3 +/- 2.8 days and for colostomy patients, 25.7 +/- 3.8 days, counting days for both initial and colostomy closure admissions (P less than .05). Colostomy was not mandated by anatomic location or number of colonic injuries, circumference of colonic wall involved, presence of fecal contamination, or involvement of mesenteric blood supply. This study indicates that primary repair does not carry an increased risk of septic complications and saves the patient the significant risk and increased hospital stay of colostomy closure. Prospective studies addressing this area are indicated.

Does open fasciotomy contribute to morbidity and mortality after acute lower extremity ischemia and revascularization?

A retrospective review was undertaken of 127 lower extremity fasciotomies performed for compartment syndrome after acute ischemia and revascularization in 73 patients with vascular trauma and 49 patients with arterial occlusive disease. One hundred twelve (88%) fasciotomies were performed early (at the time revascularization); 15 (12%) were delayed because of late compartment syndrome diagnosis. Ninety-four (77%) patients had more than one accepted indication for fasciotomy. Double-incision fasciotomy was used in 98 (77%) extremities, single-incision fasciotomy was used in 19 (15%), and fasciotomy-fibulectomy was used in 10 (8%). Fasciotomies were closed in 88 (69%) patients an average of 14 days after surgery. Seven patients needed multiple skin grafting procedures or myocutaneous flaps to close the wound; none compromised limb salvage. Five other patients had minor wound infections that resolved. Functional status returned to preoperative levels by the time of discharge from the hospital in 59 (48%) patients. Thirty-one (24%) patients had residual lower extremity disability related to delayed union of the fracture (five), chronic neuropathy (20), leg swelling (one), or ischemic nonhealing fasciotomy wounds (three); two patients had unrelated disabilities. Fourteen (11%) amputations were required for refractory limb ischemia; two (1.6%) were required for wet gangrene of the foot, which infected the fasciotomy site; the others had open noninfected incisions. Eighteen (15%) patients died of cardiopulmonary failure or multisystem failure or both, without fasciotomy-related problems. Open fasciotomy for compartment syndrome after acute lower extremity ischemia and revascularization was associated with an increased risk of minor wound morbidity. However, limb loss and death resulted from persistent ischemia and underlying systemic disease processes or injuries, but not from open fasciotomy wound complications.

Penetrating injuries to the colon: analysis by anatomic region of injury.

The preferred method for the treatment of penetrating injuries to the colon remains a source of controversy. In our retrospective review of 65 patients with penetrating colon injuries, 33 patients were managed by colostomy formation, 30 were treated by primary repair, and two had exteriorized repair with early return to the abdominal cavity (drop back). The anatomic location of injury was ascending colon in 19 (29%), transverse colon in 20 (31%), descending colon in 22 (34%), and multiple sites in four (6%). The average penetrating abdominal trauma index (PATI) was 24 (ascending colon injuries, 23; transverse colon, 26; descending colon, 24; and multiple colon sites, 28). Overall septic morbidity was 15/65 (23%). Colostomy closure was later done in 32/33 (97%), with a morbidity of 7/32 (22%). The mean length of hospital stay for primary repair was ten days and for colostomy (including both required hospital stays), 26 days (P less than .05). These data suggest that primary repair is as safe as colostomy formation for the management of penetrating colon injuries, regardless of anatomic site of injury.

Tube thoracostomy for occult pneumothorax: a prospective randomized study of its use.

Occult pneumothorax is defined as a pneumothorax that is detected by abdominal computed tomographic (CT) scanning, but not routine supine screening chest roentgenograms. Forty trauma patients with occult pneumothorax were prospectively randomized to management with tube thoracostomy (n = 19) or observation (n = 21) without regard to the possible need for positive pressure ventilation, to test the hypothesis that tube thoracostomy is unnecessary in this entity. Eight of the 21 patients observed had progression of their pneumothoraces on positive pressure ventilation, with three developing tension pneumothorax. None of the patients with tube thoracostomy suffered major complications as a result of the procedure. Hospital and ICU lengths of stay were not increased by tube thoracostomy. Patients with occult pneumothorax who require positive pressure ventilation should undergo tube thoracostomy.

A prospective evaluation of thoracoscopy for the diagnosis of penetrating thoracoabdominal trauma.

Penetrating thoracoabdominal trauma presents a difficult diagnostic dilemma. Violation of the diaphragm may be very difficult to establish. Conventional diagnostic procedures such as chest radiography, computed tomography, and diagnostic peritoneal lavage have been shown to be unreliable. Mandatory exploratory celiotomy carries a 20%-30% negative rate. Twenty-eight patients with penetrating thoracoabdominal trauma over a 6-month period were prospectively evaluated by thoracoscopy at a major urban trauma center. All patients were hemodynamically stable, had no indications for immediate celiotomy, and demonstrated thoracic injury on chest radiography or physical examination. All thoracoscopy was performed in the operating room under general anesthesia. Patients consisted of 25 males and 3 females with an age range of 15-48 years. Mechanism of injury consisted of 24 stab wounds and 4 gunshot wounds. Twelve of the procedures were for right chest wounds and 16 involved the left hemithorax. Diaphragmatic injury was identified at thoracoscopy in 9 patients (32%), with all confirmed and repaired at celiotomy. Eight of 9 patients (89%) undergoing celiotomy were found to have significant intra-abdominal injuries requiring surgical repair. Thoracoscopy was also useful for evacuation of blood from the pleural space. There were no procedure-related complications. Thoracoscopy is a safe, accurate, reliable diagnostic technique for evaluating thoracoabdominal penetrating trauma. It is less invasive than celiotomy and has the added benefit of diagnosis and therapy of the intrathoracic injuries.

Transtracheal needle catheter ventilation in complete airway obstruction: an animal model.

Transtracheal needle catheter ventilation (TNCV) may be used as an alternative airway when contraindications to endotracheal intubation exist. A feline model tested the efficacy of low-flow oxygen delivery, and initial data were gathered to define proper catheter calibers to effect adequate oxygenation and ventilation. Cats were anesthetized, trachea intubated, and ventilated for 30 minutes with a pressure-regulated ventilator. Arterial and venous pressures were monitored, and a chest tube was inserted to measure intrathoracic pressures. Arterial blood gas analysis was performed every five minutes during the baseline period. The endotracheal tube was then removed, the trachea cross-clamped, and TNCV instituted. Oxygen flow rates of 1, 3, and 5 L/min were varied with catheter sizes of 14, 16, and 18 g. Data demonstrated that TNCV provided adequate oxygenation and ventilation with flow rates of 3 and 5 L/min with the 14- and 16-g catheters. Satisfactory oxygenation could be obtained with these flow rates with the 18-g catheter, but ventilation was inadequate. Ventilation was unsatisfactory with the 1 L/min flow rate in all catheter sizes. These preliminary data indicate that a minimum catheter:trachea cross-sectional area ratio of 0.03 may be required to obtain oxygenation and ventilation with low-flow oxygen rates of 3 to 5 L/min in cats.