Posttraumatic Adult Respiratory Distress Syndrome Research Articles

Extracorporeal membrane oxygenation for adult respiratory distress syndrome in trauma patients: A case series and systematic literature review.

Venovenous extracorporeal membrane oxygenation (vv-ECMO) is an established salvage therapy for severe respiratory failure, and may provide an alternative form of treatment for trauma-induced adult respiratory distress syndrome (ARDS) when conventional treatments have failed. The need for systemic anticoagulation is a relative contraindication for patients with bleeding risks, especially in multitraumatic injury. We describe a case series of four trauma patients with ARDS who were managed with ECMO admitted to the neuro critical care unit at Addenbrooke's Hospital, Cambridge (UK), from January 2000 to January 2016. We performed a systematic review of the available literature to investigate the safety and efficacy of vv-ECMO in posttraumatic ARDS, focusing on the use of different anticoagulation strategies and risk of bleeding on patients with multiple injuries. Thirty-one patients were included. A heparin bolus was given in 16 cases. Eleven patients developed complications during treatment with ECMO with three cases of major bleeding. In all documented cases of bleeding a bolus and infusion of heparin was administered, aiming for an activated clotting time (ACT) target longer than 150 seconds. Two patients treated with heparin-free ECMO developed thromboembolic complications. Four patients died, and death was never directly or indirectly related to use of ECMO. vv-ECMO can be lifesaving in respiratory failure. Our experience and our literature review suggest that vv-ECMO should be considered as a rescue treatment for the management of severe hypoxemic respiratory failure secondary to ARDS in trauma patients.For patients with a high risk of bleeding, the use of ECMO with no initial anticoagulation could be considered a valid option. For patients with a moderate risk of bleeding, use of a heparin infusion keeping an ACT target shorter than 150 seconds can be appropriate. Therapeutic study, level V.

The Epidemiology of Posttraumatic Adult Respiratory Distress Syndrome

Although adult respiratory distress syndrome is an important early complication of blunt trauma, the epidemiology and risk factors for its development remain poorly defined. The aims of this study were to determine the prevalence and demographics of this complication in a prospective cohort series of patients admitted to the hospital following injury. We also assessed the contribution of the severity and pattern of the injury to the risk of this complication developing. By identifying factors associated with the highest risk of the development of adult respiratory distress syndrome, we aimed to produce guidelines to facilitate earlier detection. We prospectively studied 7192 patients admitted to a single university hospital, over an eight-year period, for treatment of a traumatic injury. With the exception of patients who had sustained a hip fracture or who had been discharged within seventy-two hours after admission, all patients who required hospital admission following trauma, were older than thirteen years of age, and were a resident within the catchment area were included in the analysis. The prevalence and demographics of posttraumatic adult respiratory distress syndrome were identified for patients who had sustained musculoskeletal, thoracic, abdominal, and head injuries, either in isolation or in combination. The relative risks of this condition developing were calculated according to the injury pattern. Multiple logistic regression analysis was performed to identify the most highly significant predictors of the development of adult respiratory distress syndrome. Adult respiratory distress syndrome developed in thirty-six (0.5%) of the patients. The prevalence was significantly higher among younger patients (p = 0.002), and 83% of the cases followed high-energy trauma. The prevalence of adult respiratory distress syndrome after isolated thoracic, head, abdominal, or extremity injury was <1%. Patients with injuries to two anatomical regions had a higher prevalence (up to 2.9%), and those with injuries to three anatomical regions had an even higher prevalence (up to 10.2%). Multiple logistic regression analysis showed the Injury Severity Score, the presence of a femoral fracture, the combination of abdominal and extremity injuries, and observations of compromised physiological function on admission each to be an independent predictor of the later development of adult respiratory distress syndrome. The prevalence of adult respiratory distress syndrome increases with injury severity and combinations of injuries to more than one anatomical region. We have been able to quantify the importance and relative risks associated with these injuries. The implications of our findings with regard to facilitating early detection of this complication are discussed.

A 9-year, single-institution, retrospective review of death rate and prognostic factors in adult respiratory distress syndrome.

To evaluate, at a single institution, the adult respiratory distress syndrome (ARDS) death rate in critically ill ventilated surgical/trauma patients and to identify the factors predicting death in these patients. The prognostic features affecting mortality at the onset of ARDS have not been clearly defined. Defining rare characteristics would be valuable because it would allow for better stratification of patients in clinical trials and more appropriate utilization of constrained resources in ICU environments. A retrospective analysis of 980 ventilated surgical and trauma intensive care unit patients from January 1990 to December 1998 was performed at Rhode Island Hospital. One hundred eleven adult intensive care unit patients with ARDS were identified using the criteria of Lung Injury Score more than 2.50 and the definition from the American-European Consensus Conference. Slightly more than half were trauma patients, 57% were men, and the median age was 59 years. The overall death rate was 52%. Patients were segregated by admission date to the intensive care unit (before or after January 1, 1995). Severity of illness was measured by the Revised Trauma Score for trauma patients and the Acute Physiology and Chronic Health Evaluation III for surgical patients. The Multiple Organ Dysfunction Score was determined on the day of onset of ARDS for all patients. Other recorded variables were age, sex, intensive care unit length of stay, length and mode of ventilation, presence or absence of tracheostomy, ventilation variables of peak and mean airway pressures, lung injury scores, elective versus emergency surgery, and presence or absence of pneumonia. There was a significant decrease in the ARDS death rate from the period 1990 to 1994 to the period 1995 to 1998. The major reason for the decline was a reduction in the posttraumatic ARDS death rate. Lung-protective ventilation strategies were used more frequently in the second period than in the first, and the death rate was significantly decreased in trauma patients in the second period when lung-protective ventilation modes were used. Predictors of death at the onset of ARDS were advanced age, Multiple Organ Dysfunction Score of 8 or more, and Lung Injury Score of 2.76 or more. In this single-institution series, the death rate from ARDS declined from 1990 to 1998, primarily in posttraumatic patients, and the decrease is related to the use of lung-protective ventilation strategies. Based on this patient population, the authors developed a statistical model to evaluate important prognostic indicators (advanced age, organ system and pulmonary dysfunction measurements) at the onset of ARDS.

Prediction of posttraumatic adult respiratory distress syndrome by albumin excretion rate eight hours after admission.

Adult respiratory distress syndrome (ARDS) in trauma victims carries a mortality on the order of 50%. An early feature is an increased capillary permeability causing an extravasation of plasma proteins and water, leading to interstitial edema. In the kidney, the increase in microvascular permeability is manifested as increased albumin excretion detectable by sensitive immunoassay. Forty seven trauma victims were studied for 5 days; 32 of them had Injury Severity Scores > 18. A diagnosis of ARDS was made on the recommendations of the American-European Consensus Conference on ARDS (1994). Eight patients developed ARDS, five developed pulmonary dysfunction, and the remainder showed no significant pulmonary abnormality. Using the near patient urine albumin immunoassay, albumin excretion rate (AER) was measured after admission. For patients with Injury Severity Score > 18, the median (95% confidence interval) AER 8 hours after admission was 63 (range, 40-99) microg per minute for those without impaired lung function and 339 (range, 162-454) microg per minute for those in the combined ARDS and pulmonary dysfunction group (Mann-Whitney test, p = 0.0004). The median AER was 51 (range, 27-98) microg per minute for patients with Injury Severity Score < 18. The positive predictive value for the development of ARDS or pulmonary dysfunction of AER > 130 microg per minute was 85%, with a negative predictive value of 95%. These data indicate that the capillary leak associated with the subsequent development of pulmonary dysfunction and ARDS can be detected within 8 hours of admission at the patient's bedside, thus providing a means of early identification of patients at greatest risk and allowing for early intervention.

Temporal patterns of hemodynamics, oxygen transport, cytokine activity, and complement activity in the development of adult respiratory distress syndrome after severe injury.

The aim of this study was to search for early inflammatory mediators in severely traumatized patients that could predict the occurrence of adult respiratory distress syndrome (ARDS). We measured sequential plasma levels of tumor necrosis factor (TNF), interleukin 1 (IL-1), interleukin 6 (IL-6), interleukin 8 (IL-8), complement fragment C3a, and endotoxin. In addition, we measured sequentially the values of hemodynamics, oxygen transport, and pulmonary function. The temporal patterns seen in the patients who developed ARDS were compared with those who did not. In the patients who developed ARDS, the first observed findings were low cardiac index (CI) and oxygen delivery (DO2) followed by progressive increases in IL-6, IL-8 and C3a levels, worsening of pulmonary function, and increases in hemodynamic values. The maximum values of IL-6, IL-8, and C3a occurred after the onset of ARDS. In the patients who did not develop ARDS, initial oxygen transport values were not low, the levels of IL-6, IL-8, and C3a decreased rapidly from their initial peaks, and there were no further increases in hemodynamic values. In both ARDS and nonARDS patients, no measurable quantities of TNF, IL-1, or endotoxin were found. We concluded that none of the mediators we measured reached their peaks before the onset of ARDS and none were found to be predictive of posttraumatic ARDS. However, these and other mediators may augment or intensify the development of ARDS.

The effect of kinetic positioning on lung function and pulmonary haemodynamics in posttraumatic ARDS: a clinical study

In the treatment of adult respiratory distress syndrome (ARDS) no breakthrough has been achieved so far. In several cases of severe ARDS in multiply injured patients we have seen improvements of lung function by means of continuous body positioning. We therefore compared the effect of kinetic positioning (KIN) on lung function and haemodynamics in ARDS patients with conventional (CON) supine positioning. Pulmonary and systemic haemodynamics were determined on the basis of pulmonary artery catheter measurements. On a daily basis oxygenation ratio ( PaO 2 FiO 2 ) and pulmonary shunt ( Os Ot , per cent) were calculated. Extravascular lung water (EVLW, ml/kg BW) was determined by the double indicator thermodilution technique. Twenty-two patients were included: KIN, N = 11, CON, N = 11. Mortality from ARDS in KIN patients was 18.2 per cent ( N = 2): in CON patients it was 63.6 per cent ( N = 7). The oxygenation ratio ( PaO 2 FiO 2 ) increased significantly in KIN patients from 140 + 45 (day 0) to 237 + 40 ( P < 0.05) (day 5); in CON patients no improvement was seen (143 + 48 (day 0). 133 + 44 (day 5); n.s. between groups at day 0: P < 0.05 between groups at day 5). Pulmonary shunt decreased significantly from 26.6 + 4 per cent (day 0) to 12.5 + 2 per cent (day 5) ( P < 0.05) in KIN patients and was 36.6 + 6 per cent at day 0 and 31.4 + 2 per cent at day 5 in CON patients ( P < 0.05 between groups at day 5). In KIN patients EVLW was 11.1 + 2 ml/kg BW at day 0 and 9.4 + 1 ml/kg BW at day 5, and in CON patients it was 12.9 + 2 ml/kg BW at day 0 and 17.4 + 3 ml/kg BW at day 5. There were no significant changes of systemic haemodynamics between the groups or compared with day 0. In ARDS-patients submitted to body positioning lung function improved significantly compared with patients submitted to conventional supine positioning without causing haemodynamic side effects. Continuous body positioning might be a promising supportive treatment regimen in posttraumatic ARDS.

Influence of thoracic trauma and primary femoral intramedullary nailing on the incidence of ARDS in multiple trauma patients

In multiple trauma patients the development of pulmonary complications (pneumonia, posttraumatic adult respiratory distress syndrome (ARDS)) represents a major problem and can have a substantial impact on the duration of intensive care treatment as well as on outcome. An association between the timing of stabilisation of long bone fractures and the incidence of pulmonary complications has been discussed. In several studies, primary fracture stabilisation of femoral shaft fractures, preferably by intramedullary stabilisation (Lhowe and Hansen, 1988), was shown to reduce the incidence of pneumonia and ARDS and was therefore advocated (Goris et al., 1982; Tscherne, 1983; Kwasni et al., 1986; Ruedi and Wolff, 1975; Bone et al., 1989; Johnson et al., 1985; Behrmann et al., 1990). Some authors generally recommend primary intramedullary femoral nailing in multiple trauma patients (Bone, 1993).

Intravascular Oxygenation for Advanced Respiratory Failure

Severe acute respiratory failure of varying etiology may require the temporary use of artificial gas exchange devices. So far, extracorporeal membrane oxygenation and extracorporeal carbon dioxide removal have been used successfully for this purpose. A totally implantable intravascular oxygenator (IVOX) recently became available. The authors have used IVOX in three patients who presented with severe respiratory failure secondary to pneumonia (n = 2) and post-traumatic adult respiratory distress syndrome (n = 1). At the time of implantation, all patients had hypoxemia (PaO2 less than 60) despite a 100% inspired oxygen concentration and forced mechanical ventilation. The duration of IVOX therapy ranged from 12 to 71 hr. All patients initially showed improvement in arterial oxygenation, allowing for moderate reduction of ventilator therapy after several hours. In one patient the pulmonary status deteriorated further, and she died from multiple organ failure despite IVOX therapy. One patient could be stabilized but died from other causes. The third patient is a long-term survivor 18 months after IVOX therapy. Gas transfer capabilities of IVOX are limited when compared to extracorporeal membrane oxygenation, and this may restrict its clinical applicability in cases of severe adult respiratory distress syndrome. However, IVOX may be used successfully in selected patients with less severe respiratory failure.

HIGH LEVEL POSITIVE END-EXPIRATORY PRESSURE (PEEP) MANAGEMENT IN TRAUMA ASSOCIATED ADULT RESPIRATORY DISTRESS SYNDROME (ARDS)

This study evaluated the effect of high-level positive end-expiratory pressure (PEEP) on mortality, barotrauma, intrapulmonary shunt (Qsp/Qt), and oxygen delivery (DO2) in posttraumatic adult respiratory distress syndrome (ARDS). All hypoxemic trauma patients admitted to the surgical intensive care unit (SICU) in 1989-1990 who received PEEP greater than 15 cm H2O were included. The PEEP was titrated to achieve an intrapulmonary shunt (Qsp/Qt) of approximately 0.20, and FIO2 was weaned to less than 0.50. Hemodynamic and pulmonary variables at four distinct intervals were recorded. Fifty-nine patients received PEEP greater than 15 cm H2O. Of these, 19 patients died of severe head injury or uncontrollable hemorrhage (16 within 48 hours). Forty (29 male, 11 female) were evaluated in detail. The PEEP levels ranged from 18-50 cm H2O with a mean of 27. PaO2/FIO2 ratios and Qsp/Qt improved as PEEP therapy was titrated. Cardiac index and oxygen delivery were maintained or improved throughout PEEP therapy by transfusion and fluid resuscitation, with a mean maximum positive fluid balance of 21.1 L and an average of 51 units of blood and blood products transfused per patients during their SICU stay. Twenty-nine (73%) had evidence of barotrauma, the majority being pneumothoraces clearly related to the initial trauma. Only three (7.5%) had evidence of barotrauma not related to trauma or line insertion. Eight of 40 patients (20%) died. Mean ISS and RTS for the entire group were 32 and 5.88, respectively. We conclude that titration of PEEP to achieve a Qsp/Qt of approximately 0.20 is an attainable goal. This was accomplished with minimal hemodynamic effects or barotrauma and a low mortality rate.

Increased PMN CD11b/CD18 expression following post-traumatic ARDS

We investigated the role of polymorphonuclear leukocytes (PMN) in the pathogenesis of post-traumatic adult respiratory distress syndrome (ARDS). Two groups of patients were studied: Group I ( n = 29) represents trauma patients studied within 24 hr of admission to the SICU, and Group II ( n = 10) represents a subset of Group I patients who subsequently developed ARDS. Circulating pulmonary artery PMN were then assayed for CD11b/CD18 expression, MTT-Formazan production, intracellular H 2O 2 production, and superoxide anion release. PMN from Group II patients were upregulated with regard to all of the PMN functions assayed within 24 hr of the diagnosis of ARDS being made. Subsequently, longitudinal assays were performed on 17 patients at risk for the development of ARDS. In 6 of 7 patients prior to the clinical recognition of ARDS, CD11b/CD18 expression and MTT-Formazan production increased significantly over baseline. These results suggest that: (i) ARDS coincides with increased CD11b/CD18 expression on PMN cell surfaces, (ii) PMN oxidative metabolism increases at the onset of ARDS, and (iii) changes in circulating pulmonary artery PMN may provide markers for the development of ARDS in the traumatized patient.

Gamma scintigraphic imaging of lung microvascular permeability in adult respiratory distress syndrome

The sequence of lung microvascular permeability (LMVP) changes in early direct posttraumatic and late indirect pancreatitis-induced adult respiratory distress syndrome (ARDS) was studied and compared with that of a control group, as well as non-ARDS ICU patients. A computerized large field of view gamma camera was used to measure LMVP simultaneously over both lungs by In 113m-labeled transferrin and Tc 99m-labeled erythrocytes. The LMVP index (LMVPI) (%/h) was used to quantify LMVP in the dynamic scintigraphic measurement. In the control group the LMVPI was 2.6 +/- 2.8%/h for the right and 2.0 +/- 2.8%/h for the left lung. Similar values were found in mechanically ventilated ICU patients without ARDS (group A) on admission (right LMVPI 3.2 +/- 2.6, left LMVPI 2.6 +/- 2.7%/h) and 4 days later (right LMVPI 3.9 +/- 2.6, left LMVPI 2.3 +/- 1.8%/h). Interestingly, the initial evaluation of patients with direct early posttraumatic ARDS (lung contusion) (group B) showed significantly (p less than .01) elevated LMVP for the contused side (LMVPI 10.8 +/- 5.1%/h), but normal values for the nontraumatized lung (LMVPI 3.9 +/- 3.4%/h), whereas 4 days later the LMVP increased significantly (p less than .05) on the primarily healthy side (LMVPI 8.0 +/- 5.0%/h) while remaining elevated for the traumatized lung (LMVPI 10.9 +/- 6.0%/h).(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory index/pulmonary shunt relationship

The relationship between the respiratory index (RI = alveolar-arterial oxygen gradient [P(A-a)O2] normalized by PaO2) and the pulmonary shunt (Qsp/Qt) has been examined in 929 studies from 240 critically ill post-traumatic patients. Of these, 88 patients (443 studies) were individuals who developed post-traumatic adult respiratory distress syndrome (ARDS) and 152 were patients (486 studies) who did not develop ARDS. This study demonstrates that the RI to Qsp/Qt [RI/(Qsp/Qt)] relationship was significantly (p less than .0001) increased in patients who developed fatal ARDS compared with those who did not develop ARDS, or with those whose ARDS resolved. Because of the increased oxygen consumption (VO2) in ARDS patients in association with their severe limitations in gas exchange (RI) and increased Qsp/Qt, surviving ARDS patients had a significant increase in the cardiac index which resulted in a higher oxygen delivery to VO2 ratio. ARDS patients showed significant (p less than .0001) evidence of increased pulmonary vascular tone, correlated with the increase in the RI/(Qsp/Qt) relationship. In addition, those patients with high RI/(Qsp/Qt) also had increased right ventricular (RVSW) to left ventricular work (LVSW) ratios which were shown to be a direct function of the rise in RI. This increase in both RVSW/LVSW and RI/(Qsp/Qt) ratios was significantly (p less than .0001) correlated with an increased mortality. Thus, the RI/(Qsp/Qt) relationship, which can be obtained from arterial and mixed venous blood gases and saturations only, can be used to predict the severity of the ARDS process as well as important pulmonary vascular and right ventricular overload consequences.

Sequential Patterns of Eicosanoid, Platelet, and Neutrophil Interactions in the Evolution of the Fulminant Post-traumatic Adult Respiratory Distress Syndrome

Thirty multiply injured blunt-trauma patients at high risk for development of ARDS (multisystem trauma including more than one organ or extremity, Injury Severity Score of 26 or more, hypotension and need for 1500 mL or more blood within the first hour after admission, and PaO2 less than or equal to 70 torr) were studied sequentially with blood and physiologic evaluations beginning immediately after injury and every eight hours for eight days, or until death, to study the evolution of the ARDS process. Mixed venous blood samples were obtained for eicosanoids PGE2, PGF2 alpha, thromboxane B2, PGI2 (6-KetoPGF1 alpha) and leukotriene B4 (LTB4). Platelet (PLAT), and neutrophil (WBC) counts were also done and plasma elastase was measured. At 7:00 AM each day patient neutrophils were obtained for a study of zymosan-activated superoxide production using a chemiluminescence assay. These data were correlated with physiologic measurements of the Respiratory Index (RI), per cent pulmonary shunt (QS/QT), and respiratory compliance measures. Seven patients developed a fulminant post-traumatic ARDS syndrome within 96 hours after injury. Twelve patients without ARDS developed sepsis (TS) four or more days after injury, and 11 had uncomplicated postinjury courses (TR). Compared to both TR and TS, ARDS had a significant (p less than 0.01) rise in neutrophil superoxide production beginning on day 2 through day 4 after injury. This was preceded by rises in PGE2 and LTB4, which were significantly correlated with subsequent falls in PLAT and WBC and rises in TXB2, PGF1, and superoxide production and followed by increases in RI, QS/QT, and a fall in compliance. The significant difference in the pattern and sequence of events in ARDS compared to TR and TS patients suggests that in ARDS the earliest event may be related to peripheral release of PGE2 and LTB4 due to platelet activation and lung sequestration with release of PGF2 alpha, and by aggregation and leukocyte adherence with release of elastase. However, fulminant ARDS mortality appears to be related to the subsequent amplification of the LTB4 leukocyte activation with superoxide production that does not achieve significance before the second day after injury and rises to a maximum by day 4 after injury. These data suggest that post-trauma ARDS follows a different evolutionary pattern than that reported in animal models and is also different from that seen in human TS or TR patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Pulmonary microthrombosis in severe adult respiratory distress syndrome.

Pulmonary microvascular occlusive disease has been investigated using balloon occlusive pulmonary angiography in 31 patients with severe adult respiratory distress syndrome (ARDS) of different origins (14 patients with pneumonia, nine with multiple injury, eight with sepsis). Multiple pulmonary artery filling defects (PAFD) were detected in 13 (42%) patients, with a seven (78%) in nine incidence among those with posttraumatic ARDS. The presence of PAFD did not correlate with the severity of the respiratory failure, with the pulmonary hemodynamic alterations (pulmonary hypertension and increased vascular resistance), or with the final outcome (mortality rate was 54% among patients with PAFD and 61% among those with normal angiograms). These findings suggest that widespread pulmonary microthrombosis is a common event in patients with polytrauma and respiratory failure, with an important pathophysiologic role in the onset of posttraumatic ARDS.

Determinants of early adult respiratory distress syndrome with special reference to chest radiography. A retrospective analysis of 220 patients with major skeletal injuries.

The medical records of 220 consecutive patients with traumatic injuries admitted to the intensive care unit in the years 1974-1982 were scrutinised in an attempt to find radiographic signs and clinical determinants of early adult respiratory distress syndrome (ARDS). All patients included in this study were considered to run a risk of developing ARDS and had 'pure' major fractures in the sense that there were no accompanying severe brain, chest or abdominal injuries. There were no deaths in this series of patients. ARDS developed in 27 patients (12.3%), on an average on the second day of trauma. Chest radiographs of 21 of these patients showed features indicative of ARDS, whereas those of the other 6 patients were normal despite hypoxaemia. In most of the 27 patients the only radiographic manifestation of ARDS was interstitial oedema; only a minority presented with alveolar oedema in addition. In 6 patients no radiographic changes ever occurred. Ventilator treatment with positive end expiratory pressure may have prevented the pulmonary insufficiency from becoming radiographically manifest. The clinical determinants of post-traumatic ARDS were a high fracture index, based on the number and severity of fractures, implying severe trauma, and shock on admission. Fluid overload was not found to be the cause of ARDS.

Quantification of asymmetric lung pathophysiology as a guide to the use of simultaneous independent lung ventilation in posttraumatic and septic adult respiratory distress syndrome.

The management of impaired respiratory gas exchange in patients with nonuniform posttraumatic and septic adult respiratory distress syndrome (ARDS) contains its own therapeutic paradox, since the need for volume-controlled ventilation and PEEP in the lung with the most reduced compliance increases pulmonary barotrauma to the better lung. A computer-based system has been developed by which respiratory pressure-flow-volume relations and gas exchange characteristics can be obtained and respiratory dynamic and static compliance curves computed and displayed for each lung, as a means of evaluating the effectiveness of ventilation therapy in ARDS. Using these techniques, eight patients with asymmetrical posttraumatic or septic ARDS, or both, have been managed using simultaneous independent lung ventilation (SILV). The computer assessment technique allows quantification of the nonuniform ARDS pattern between the two lungs. This enabled SILV to be utilized using two synchronized servo-ventilators at different pressure-flow-volumes, inspiratory/expiratory ratios, and PEEP settings to optimize the ventilatory volumes and gas exchange of each lung, without inducing excess barotrauma in the better lung. In the patients with nonuniform ARDS, conventional ventilation was not effective in reducing shunt (QS/QT) or in permitting a lower FIO2 to be used for maintenance of an acceptable PaO2. SILV reduced per cent v-a shunt and permitted a higher PaO2 at lower FIO2. Also, there was x-ray evidence of ARDS improvement in the poorer lung. While the ultimate outcome was largely dependent on the patient's injury and the adequacy of the septic host defense, by utilizing the SILV technique to match the quantitative aspects of respiratory dysfunction in each lung at specific times in the clinical course, it was possible to optimize gas exchange, to reduce barotrauma, and often to reverse apparently fixed ARDS changes. In some instances, this type of physiologically directed ventilatory therapy appeared to contribute to a successful recovery.

Respiratory Insufficiency

Adult respiratory distress syndrome (ARDS) is defined and the causes and mechanisms of pulmonary edema as they relate to posttraumatic ARDS are discussed. The standard treatment and potential therapies of the future are also considered.

Pathogenesis of respiratory failure (ARDS) after hemorrhage and trauma: II. Cardiorespiratory patterns after development of ARDS.

Hemodynamic and oxygen transport variables were studied in a series of 60 patients who sustained adult respiratory distress syndrome (ARDS) from hemorrhage and trauma; measurements were made during the period of their ARDS and in survivors after their recovery from ARDS. In general, cardiac index (CI) and myocardial performance were increased over normal values; they were greater in trauma patients than in hemorrhage patients and greater in the survivors than in nonsurvivors. The mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance index (PVRI) were high in all groups. Blood volume and hemoglobin (Hgb) concentrations were reduced especially in the nonsurviving hemorrhage patients; hemoglobin saturation (SaO2) and oxygen tension (PaO2) were low initially, but usually responded to therapy; oxygen consumption (VO2) was normal or high in all groups, and was greater in survivors than in nonsurvivors, and greater in trauma than in hemorrhage. Thus, the patient with post-traumatic ARDS has circulatory and metabolic needs which are greater than normal values defined by values from healthy unstressed volunteers and also somewhat greater than hemorrhage and trauma patients without ARDS. Optimal blood volume, hemodynamic and oxygen transport values defined by the survivor's values as well as the standard respiratory care are recommended as goals for preventive or ealy therapy of these patients. Volume therapy should be given provided it does not elevate the pulmonary arterial wedge pressure (WP) above 18 mm Hg to avoid overloading the pulmonary vascular bed and causing pulmonary edema.

Post-traumatic bronchial stenosis and acute respiratory insufficiency

A 31-year-old woman sustained multiple injuries, including severe contusion of the right lung with massive subcutaneous emphysema. Four weeks later she was transferred to our institution with post-traumatic adult respiratory distress syndrome and carbon dioxide retention, resulting from a postlaceration stenosis of the left main-stem bronchus. Bronchoplasty was contraindicated because of the serious condition of the patient. Repeated bronchial dilatations produced initial improvement in oxygenation and minute ventilation requirements. However, because of the nature of the stenosis and the lack of recovery of right lung function, the patient's encouraging clinical course reached a plateau and attempts at weaning from the respirator were unsuccessful. Bronchoplasty was performed on postadmission day 50 and resulted in gradual recovery of pulmonary function. Six months following discharge, the patient continues a steady improvement. Management of the patient's injuries represented a unique challenge previously unencountered.

Post-traumatic Adult Respiratory Distress Syndrome

Post-traumatic Adult Respiratory Distress Syndrome