Comparison of multiplane transesophageal echocardiography and contrast-enhanced helical CT in the diagnosis of blunt traumatic cardiovascular injuries.

BACKGROUND: Multiplane transesophageal echocardiography (TEE) and helical computed tomography (CT) of the chest have been validated separately against aortography for the diagnosis of acute traumatic aortic injuries (ATAI). However, their respective diagnostic accuracy in identifying blunt traumatic cardiovascular lesions has not been compared. METHODS: During a 3-yr period, 110 consecutive patients with severe blunt chest trauma (age: 41 +/- 17 yr; injury severity score: 34 +/- 14) prospectively underwent TEE and chest CT as part of their initial evaluation. Results of both imaging methods were interpreted independently by experienced investigators and subsequently compared. All cases of subadventitial acute traumatic aortic injury were surgically confirmed. RESULTS: Seventeen patients had vascular injury and 11 had cardiac lesions. TEE and CT identified all subadventitial disruptions involving the aortic isthmus (n = 10) or the ascending aorta (n = 1) that necessitated surgical repair. In contrast, CT only depicted one disruption of the innominate artery. TEE detected injuries involving the intimal or medial layer, or both, of the aortic isthmus in four patients with apparently normal CT results who underwent successful conservative treatment. All cardiac injuries but two were identified only by TEE. CONCLUSIONS: In patients with severe blunt chest trauma, TEE and CT have similar diagnostic accuracy for the identification of surgical acute traumatic aortic injuy. TEE also allows the diagnosis of associated cardiac injuries and is more sensitive than CT for the identification of intimal or medial lesions of the thoracic aorta.

Reactivation of human herpesvirus type 6 in multiple organ failure syndrome.

Human herpesvirus type 6 (HHV-6) and cytomegalovirus (CMV) are known to interact with the production of cytokines. In this study, we sought to determine the incidence of HHV-6 and CMV reactivation during multiple organ failure syndrome (MOFS) and to evaluate the potential effects of viral replication on both the morbidity and mortality associated with MOFS. Viral reactivation was assessed by use of specific polymerase chain reaction (PCR) analysis of the serum samples obtained from 48 consecutive patients with MOFS (the MOFS group) and from 48 sex- and age-matched patients with <2 organ failures (the control group). In addition, HHV-6 replication was assessed in 106 blood donors (the normal group). The incidence of HHV-6 replication was higher in the MOFS group than in the control and normal groups (26 [54%] of 48 vs. 7 [15%] of 48 and 5 [5%] of 106, respectively; P<.0001), with apparently no influence on morbidity and mortality rates. In contrast, reactivation of CMV was found in a single patient. Further studies are needed to evaluate the pathogenesis of HHV-6 replication in critically ill patients.

[Refractory shock after converting enzyme inhibitor administration. Usefulness of angiotensin II]. / Choc réfractaire après administration d'un inhibiteur de l'enzyme de conversion. Intérêt d'un traitement par angiotensine II.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors are commonly used during the early phase after myocardial infarction but severe hypotension and shock have been described. CASE REPORT: A 42-year old woman underwent a conservative management for an anterior acute myocardial infarction, initially associated with a pulmonary edema. Two hours after the initiation of a treatment with ACE inhibitor administered orally (lisinopril, Zestril), a circulatory failure in conjunction with an acute renal insufficiency occurred. Right heart catheterization disclosed markedly decreased systemic vascular resistance in the presence of a preserved cardiac index. Repeated fluid challenges and intravenous administration of norepinephrine failed to improve the hemodynamic status. The refractoriness of shock raised the hypothesis of a dysregulation of the renin-angiotensin system, secondary to the treatment by ACE inhibitor. Accordingly, the patient was given angiotensin II intravenously (Hypertension) which markedly raised systemic vascular resistance, and result in subsequent regression of shock. The patient was discharged after an otherwise uneventful course. DISCUSSION: We reported a refractory shock to fluid challenges and norepinephrine after the first dose of ACE inhibitor during acute myocardial infarction. Regression of shock was possible only with angiotensin II.

[Pancytopenia and pulmonary tuberculosis. Significance of a hemophagocytic syndrome]. / Pancytopénie et tuberculose pulmonaire. Implication d'un syndrome hémophagocytaire.

Haemophagocytic syndromes or syndromes involving macrophage activation are rare complications of tuberculosis, whether they be pulmonary or polyvisceral. They are characterised by an anomalous increase in the phagocytic power of macrophages with phagocytosis of the formed elements of blood. The clinical biological picture associates a change in the general physical state accompanied by organomegaly, hyperferritinaemia and pancytopenia. Their occurrence is a poor prognostic factor and few treatment seem to check this mechanism. The authors report a rare case of marked macrophage activation syndrome complicating pulmonary tuberculosis in a patient who was HIV negative without an underlying blood disturbance and a favourable outcome.

Quantification of traumatic hemomediastinum using transesophageal echocardiography: impact on patient management.

STUDY OBJECTIVES: To determine whether the quantitative evaluation of hemomediastinum using transesophageal echocardiography (TEE) is predictive of the presence of a traumatic disruption of the thoracic aorta (TDA) or its branches in patients who have sustained severe blunt chest trauma. DESIGN: Retrospective study. SETTING: ICU of a tertiary referral teaching hospital. PATIENTS: Forty-one patients sustaining severe blunt chest trauma (32 men, nine women; mean age, 43+/-16 years; mean Injury Severity Score, 39+/-22) who underwent a TEE study were divided into two groups, patients with (group TDA+, n=15) or without (group TDA-, n=26) major vascular injury diagnosed using an alternative method such as aortography, surgery, or necropsy. The control group included 41 age- and sex-matched patients with an unremarkable TEE study performed to rule out an intracardiac source of emboli. INTERVENTIONS: The presence of hemomediastinum was quantitatively assessed by measuring the distances between the esophageal scope and anteromedial aortic wall (distance 1), and between the posterolateral aortic wall and left visceral pleura (distance 2) at the level of the aortic isthmus. An observer who was unaware of both medical history and final diagnosis measured the distances. MEASUREMENTS AND RESULTS: In group TDA+, TEE demonstrated aortic injuries in 13 patients, revealed an isolated hemomediastinum in one patient (ruptured intercostal arteries), and was unremarkable in the remaining patient, who sustained a disrupted right subclavian artery. No associated major vessel injuries were diagnosed in the group TDA- (normal aortograms). When compared to the control group, mean distances were greater in patients with chest trauma (distance 1=5.5+/-4.4 mm vs 2.7+/-0.8 mm, p=0.001; distance 2=3.8+/-5.0 mm vs 1.2+/-0.3 mm, p=0.02). The corresponding distances were even greater in group TDA+ when compared with group TDA- (distance 1=8.6+/-5.9 mm vs 3.7+/-1.5 mm, and distance 2=7.1+/-7.0 mm vs 2.0+/-1.7; for both differences, p<0.01). A threshold value of 5.5 mm for distance 1 or 6.6 mm for distance 2 had a sensitivity of 80%, a specificity of 92%, a positive and negative predictive value of 86% and 89%, respectively, for the diagnosis of underlying major vascular injury. CONCLUSIONS: TEE allows quantitative assessment of traumatic hemomediastinum. The presence of a large hemomediastinum requires further evaluation by aortography, even if the thoracic aorta appears normal during the TEE examination, in order to rule out an underlying major vascular injury which may be outside the field of view of the echocardiographer.

[Transesophageal echocardiography for diagnosis of traumatic injuries to the major intrathoracic vessels in 150 patients: the effect of the learning curve]. / Echocardiographie transoesophagienne pour le diagnostic des lésions traumatiques des grands vaisseaux intrathoraciques chez 150 patients: influence de la courbe d'apprentissage.

OBJECTIVES: To evaluate the role of transoesophageal echocardiography (TOE) in the management of patients with suspected traumatic lesions of the thoracic aorta (TLA) and its branches; to assess the influence of the learning curve on the diagnostic accuracy of TOE for the identification of TLA. STUDY DESIGN: Retrospective study. PATIENTS: The study included 150 patients (age: 41 +/- 17; Injury Severity Scale score: 31 +/- 17) who were admitted during a 4-year period for severe blunt chest trauma and who underwent a TOE study. METHODS: TOE were performed with either a monoplane (n = 54) or a multiplane probe (n = 96). In all cases, TLA were confirmed by angiography, computed tomography, surgery, or necropsy. Initially performed routinely, angiography was subsequently indicated when the TOE study was inconclusive or when a disruption of supraaortic arteries was suspected. Echocardiographic studies were reviewed by an experienced reader who was unaware of the medical history and initial conclusions. To evaluate the influence of the learning curve on the diagnostic accuracy of TOE, these conclusions were compared with the initial interpretations. RESULTS: A TLA was recognized in 25 patients out of 150 (17%), and evidenced using TOE in 22 of them. Three false negative and two false positive TOE results (needless thoracotomy) were recorded. After a learning period, the rate of inconclusive TOE studies decreased (18/150 vs 7/150: P < 0.05) and no false positive finding was recorded. The sensitivity and specificity of TOE for the diagnosis of TLA were 88 and 100%, and positive and negative predictive values were 100 and 97%, respectively. CONCLUSIONS: TOE is an accurate imaging technique for the diagnosis of TLA located at the aortic isthmus. However aortography becomes essential when injuries of the aorta branches are suspected. A learning period is required to improve the specificity of TOE for this indication.

Thrombocytopenia in the sepsis syndrome: role of hemophagocytosis and macrophage colony-stimulating factor.

BACKGROUND: Thrombocytopenia is frequently encountered in critically ill patients with the sepsis syndrome, but its mechanisms frequently remain undetermined. Hemophagocytosis has been reported as a cause of thrombocytopenia in various diseases. This prospective study was designed to assess: (1) the incidence of hemophagocytosis in patients suffering from both the sepsis syndrome and unexplained thrombocytopenia, and (2) the circulating level of the macrophage-colony-stimulating factor (M-CSF) according to the presence or absence of hemophagocytosis. METHODS: Fifty consecutive patients diagnosed with both the sepsis syndrome and thrombocytopenia of undetermined origin were studied. Hemophagocytosis was diagnosed based on microscopical examination of sternal bone marrow aspiration by two independent observers. Serum M-CSF concentrations were measured in each patient and compared with levels of a normal population (n = 59). Causes and severity of sepsis syndromes as well as serum M-CSF levels were compared between patients with and without hemophagocytosis. RESULTS: Hemophagocytosis was diagnosed in 32 patients (64%). Mean serum M-CSF levels were increased in patients when compared with normal subjects (539 +/- 141 versus 208 +/- 82 IU/mL: P < 0.001), and higher in patients with than without hemophagocytosis (580 +/- 145 versus 457 +/- 89 IU/mL: P = 0.01). Multiorgan dysfunction and infection were independent risk factors of hemophagocytosis (odds ratio = 31.3 and 6.8, 95% confidence interval (CI) = 5.4 to 177.6 and 1.0 to 47.4, P <0.0001 and P = 0.03, respectively). CONCLUSIONS: Hemophagocytosis is a frequent cause of unexplained thrombocytopenia in patients with severe sepsis syndrome. Our results suggest that M-CSF is overproduced in the sepsis syndrome, particularly when hemophagocytosis is present. The role of M-CSF in the initiation and development of hemophagocytosis remains to be determined.

[Continuous intrathecal injection of baclofen in generalized tetanus. A therapeutic alternative]. / Injection intrathécale continue de baclofène en cas de tétanos généralisé. Une alternative thérapeutique.

BACKGROUND: In France, tetanus is diagnosed predominantly in the elderly due to the absence of vaccination in this population. Mortality remains high and is mainly related to complications secondary to prolonged hospitalization, intravenous administration of benzodiazepines, and at times curares. Baclofen, a selective agonist of GABAB receptors, directly counteracts the effects of the tetanic toxin. CASE REPORT: We report the case of a 92-year-old man suffering from tetanus, who fully recovered after a myorelaxant treatment based solely on intrathecal baclofen administration. Continuous intrathecal administration of baclofen resulted in a marked muscular relaxation with minor side effects (bradycardia, sleepiness), which rapidly stopped after the cessation of the treatment. Initial careful titration is required in order to determine the optimal dose of baclofen which provides a substantial myorelaxation together with minor central effects. Low concentration of baclofen may facilitate its diffusion. DISCUSSION: Continuous intrathecal administration of barclofen appears to be a valuable alternative therapy in tetanus. This new therapeutic modality promises to improve the prognosis of this condition, especially in the elderly.

Serotonin syndrome due to an overdose of moclobemide and clomipramine. A potentially life-threatening association.

The serotonin syndrome is frequently characterized by minor neurologic manifestations that regress rapidly (such as confusion, tremor, ...). Many medications including tricyclic antidepressants, serotonin reuptake inhibitors, tryptophan and the association of monoamine oxidase inhibitors together with a serotoninergic agent have been implicated in this syndrome. In certain cases, and for poorly understood reasons, clinical manifestations can include circulatory collapse, malignant hyperthermia, convulsions and rhabdomyolysis. These forms are often fatal. Treatment, other than the withdrawal of the offending drug, is symptomatic. Dialysis may be of value in withdrawing the drug from the circulatory system. We report a patient with the serotonin syndrome of favorable outcome due to an overdose of moclobemide and clomipramine.

Routine transesophageal echocardiography for the diagnosis of aortic disruption in trauma patients without enlarged mediastinum.

OBJECTIVE: To assess the value of routine transesophageal echocardiography (TEE) in diagnosing traumatic disruption of the aorta (TDA) in trauma patients presenting without enlarged mediastinum on chest x-ray films. DESIGN: Prospective study. MATERIALS AND METHODS: TEE was routinely performed to exclude the presence of TDA in patients who sustained severe trauma secondary to abrupt deceleration collisions and presented with an upper mediastinum of fewer than 8 cm on supine chest x-ray films. Patients were divided into two groups according to the presence (group I) or absence (group II) of mediastinal hematoma diagnosed during TEE examination. Radiographic signs regarded as indicators of the presence of TDA were evaluated in both groups. RESULTS: Among the 40 consecutive patients studied, TEE demonstrated two cases of TDA associated with a mediastinal hematoma that were confirmed by both aortography and surgery. One of the patients had a normal mediastinum on presentation chest x-ray films, and the other only exhibited a blurred aortic knob. Radiographic mediastinal abnormalities suggestive of TDA were observed in 13 patients, but chest x-ray films were unremarkable in 12 patients. Twenty patients had multiple rib fractures. The frequency of chest radiographic abnormalities was not significantly higher in group I (n = 6) when compared with group II patients (n = 34). TEE examination demonstrated a normal thoracic aorta in 35 patients and was nondiagnostic in 3 patients (normal aortography). CONCLUSION: TEE should be routinely performed in victims of violent deceleration collisions, even in patients presenting apparently normal mediastinum on supine chest radiography.

Role of transesophageal echocardiography in the diagnosis and management of traumatic aortic disruption.

BACKGROUND: Traumatic disruption of the aorta (TDA) is a life-threatening injury that requires rapid diagnosis and treatment. Emergency aortography, which is the current standard diagnostic imaging modality, is invasive, time-consuming, and difficult to perform in hemodynamically unstable patients with multiple trauma. We performed transesophageal echocardiography (TEE) in patients with suspected TDA to determine the diagnostic accuracy and impact on patient management of this alternative, portable imaging modality. METHODS AND RESULTS: Thirty-two consecutive trauma patients (mean age, 40 +/- 16 years) with suspected TDA (violent deceleration accident and mediastinum > 8 cm on admission chest x-ray) prospectively underwent a TEE examination in the emergency room. Findings during TEE were compared with those encountered during aortography, surgery, or necropsy. Two subsets of traumatic aortic injuries with distinct echocardiographic signs were observed: (1) subadventitial TDA (n = 10) and (2) traumatic intimal tears (n = 3). Eighteen patients had normal TEE confirmed by aortography. One 2-mm medial tear was missed by TEE (necropsy). The sensitivity and specificity of TEE for the diagnosis of subadventitial TDA were 91% and 100%, respectively. Patients with subadventitial TDA were taken to surgery immediately, whereas patients with intimal aortic tears were treated conservatively. Eighteen patients (mean age, 57 +/- 15 years) with confirmed acute aortic dissection involving the aortic isthmus were also included to establish the echocardiographic differential diagnostic criteria between this entity and TDA. CONCLUSIONS: TEE should be considered the first-line imaging modality for the evaluation of trauma patients with suspected injuries of the thoracic aorta because of its portability, safety, diagnostic accuracy, and potential impact on patient management.

[Dynamics of the nasal colonization by methicillin resistant Staphylococcus aureus in patients hospitalized in an intensive care unit]. / Dynamique de la colonisation nasale par Staphylococcus aureus résistant à la méticilline (SAMR) chez les malades hospitalisés dans un service de réanimation.

Prospective study on MRSA nasal cariage was done during two months in an intensive care unit in Limoges University Hospital. Nasal swab specimens were taken daily and cultured on selective and non selective media. Sixty eight patients were included in this study (878 swab collected, 575 MRSA isolated). Patients mean âge was 62 years and stay period mean was 12.3 days (median: 7 days). Among these patients, 16 were already carrying MRSA when entering in the unit and 26 became positive for MRSA during their stay. The mean colonisation delay was 5.5 days (median 4 days). All patients, except one, have shown a nasal carriage during all their stay. During the study period, 17 patients became infected and only two patients neither carried nasal MRSA before and during infection. In all cases, glycopeptide treatment did not affect nasal carriage. Colonisation and infection risk factors were discussed.

[Reactive hemophagocytic syndrome: a probably underestimated cause of thrombocytopenia in intensive acre patients]. / Syndrome hémophagocytaire réactionnel: une cause probablement sous-estimée de thrombopénie en réanimation.

Thrombocytopenia is a common feature in ICU patients which occurs usually in case of infection or septic shock. Its mechanisms, which are often unclear, include the haemophagocytic syndrome initially linked with histiocytic proliferation but probably also associated with infectious diseases. This syndrome is characterized by a phagocytosis of medullar blood cells. Reactive haemophagocytic syndrome can probably lead to thrombocytopenia in ICU patients as in this case report of a E. Coli infection.

Diagnostic accuracy and therapeutic impact of transthoracic and transesophageal echocardiography in mechanically ventilated patients in the ICU.

STUDY OBJECTIVES: To assess the respective diagnostic accuracy of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) and their therapeutic implications in mechanically ventilated patients, in the intensive care unit (ICU). DESIGN: A prospective study. SETTINGS: Intensive care units of two tertiary referral teaching hospitals. PATIENTS: One hundred eleven ICU patients (81 men and 30 women; mean age 57 +/- 16 years). Fifty-seven percent were hospitalized for medical illnesses, 16.5 percent after thoracic surgery, 10.5 percent after other surgery, and 16.0 percent for multiple trauma. Their Simplified Acute Physiologic Score was 16 +/- 5. INTERVENTIONS: The echocardiograms were performed in order to solve well-defined clinical problems. TTE was the first step of the procedure and TEE was performed only when (1) TTE did not solve the clinical problems, and (2) TTE yielded unsuspected findings requiring TEE. During each echocardiographic study, the following were noted: ventilatory mode, clinical problems, imaging quality, results, consequence on acute care, duration of the procedure, and potential complications of TEE. Diagnostic accuracy was defined as the proportion of solved problems, and therapeutic impact was defined as changes on acute care that resulted directly from the procedure. MEASUREMENTS AND RESULTS: One hundred twenty-eight consecutive TTE and 96 TEE were performed. TTE solved 60 of 158 clinical problems (38 percent), whether positive end-expiratory pressure (> 4 cm H2O) was present or not (28 of 74 vs 32 of 84: p > 0.50). TTE allowed evaluation of left ventricular function in 77 percent of cases and pericardial effusion in every case, but it did not solve most of the other clinical problems. Indeed, the diagnostic accuracy of TEE was markedly superior (95/98 vs 60/158: p < 0.001), but TEE required a physician's presence longer (43 +/- 17 min vs 27 +/- 12 min: p < 0.001). When TTE and TEE were scheduled (n = 96), TEE yielded an additional diagnosis or excluded with more certitude a suspected diagnosis, except in two cases. TEE had a therapeutic impact more frequently than TTE (35/96 vs 20/128: p < 0.001). Cardiovascular surgery was prompted by echocardiographic findings in ten patients. TEE was well tolerated in all patients; there were no complications. CONCLUSIONS: TEE is a valuable well-tolerated imaging technique in mechanically ventilated patients. For the assessment of left ventricular systolic function and pericardial effusion; however, TTE continues to be an excellent diagnostic tool, even when positive end-expiratory pressure is present. Both TTE and TEE have a therapeutic impact in approximately 25 percent of cases.

A controlled trial in intensive care units of selective decontamination of the digestive tract with nonabsorbable antibiotics. The French Study Group on Selective Decontamination of the Digestive Tract.

BACKGROUND: Selective decontamination of the digestive tract with topical nonabsorbable antibiotics has been reported to prevent nosocomial infections in patients receiving mechanical ventilation, and the procedure is used widely in Europe. However, it is unclear whether selective decontamination improves survival. METHODS: We conducted a randomized, double-blind multicenter study in which 445 patients receiving mechanical ventilation in 15 intensive care units were given either prophylactic nonabsorbable antibiotics (n = 220) or a placebo (n = 225). Topical antibiotics (tobramycin, colistin sulfate, and amphotericin B) or a placebo was administered through a nasogastric tube and applied to the oropharynx throughout the period of ventilation. The main end points were the mortality rate in the intensive care unit and within 60 days of randomization. RESULTS: A total of 142 patients died in the intensive care unit; 75 (34 percent) in the treatment group and 67 (30 percent) in the placebo group (P = 0.37). Mortality within 60 days of randomization was similar in the two groups (P = 0.40), even after adjustment for factors that were either unbalanced or individually predictive of survival in the two groups (P = 0.70). Pneumonia developed in 59 patients (13 percent) in the intensive care unit within 30 days of enrollment in the study (33 in the placebo group and 26 in the treatment group, P = 0.42). Pneumonia acquired in the intensive care unit and due to gram-negative bacilli was less frequent (P = 0.01) in the treatment group than in the placebo group. The total charges for antibiotics were 2.2 times higher in the treatment group. CONCLUSIONS: Selective decontamination of the digestive tract does not improve survival among patients receiving mechanical ventilation in the intensive care unit, although it substantially increases the cost of their care.

[Perceptions of consequences of chronic respiratory insufficiency in subjects over 65 years with home respiratory assistance. Apropos of 85 patients]. / Perception des conséquences de l'insuffisance respiratoire chronique chez les sujets de plus de 65 ans ayant une assistance respiratoire à domicile. A propos de 85 patients.

Chronic respiratory diseases (C.R.D.) induce changes in daily activities and mood for the patients who require respiratory assistance (oxygen delivery or ventilation). The aim of this study was to compare physical and social consequences of this disease. A self administered questionnaire was sent to one hundred patients, over sixty five years of age, who were affiliated with the "Association Limousine d'Aide aux Insuffisants Respiratories" (A.L.A.I.R.). The mean age was 72.4 +/- 0.66 (65-92), the mean PaO2 was 54 mm Hg +/- 0.2 (39-76). C.R.D. was stable during the study and treatments did not change. The questionnaire was composed of four scales and twenty-eight subjects; each item was weighed for importance. Subjects included: symptoms, mood, sleep, relationships with their wife or family, home activities. Eighty-five questionnaires were analysed. Reproductibility was good (92%) and non-responses to some questions was less than 10%. Coherence between the scales and the twenty-eight items was poor. Regression linear analysis found that only dyspnea was correlated with PaO2 (p < 0.007). For patients, the most important items were: abnormalities of home activities (37%), dyspnea (38%), relationships with their wife (39%) or family (45%), dependence (52%) and perception of A.L.A.I.R. (77%). Quality of life is an important concept for these patients with C.R.D. versus clinical symptoms. Perception of respiratory assistance is very good.

Antibiotic levels in bronchial tree and in serum during selective digestive decontamination.

Selective digestive decontamination has been found to prevent pulmonary infections in mechanically ventilated patients. The aims of this study were: 1) to determine whether detectable levels of antibiotics could be found in bronchial tree secretions of patients receiving SDD, and 2) to evaluate antibiotic serum levels. In 15 patients receiving mechanical ventilation and SDD for 10 days or more, tobramycin and amphotericin B levels were determined every 3 days in the following specimens: tracheal aspirates, distal bronchial secretions and blood samples. 82% of tracheal aspirates contained detectable (greater than 0.18 mg/l), tobramycin concentrations; the levels varied widely between patients and large day-to-day variations were observed. Every patient had at least 1 tracheal aspirate with tobramycin level higher than 0.5 mg/l during his course. 40% of distal specimens contained detectable tobramycin levels (10 patients). Serum determinations showed detectable concentration of tobramycin in 50% of the specimens (9 patients). Two patients with renal failure had serum tobramycin levels higher than 2 mg/l. In 13 tracheal aspirates cultures were positive and 15 species were isolated; 13 had a MIC higher than the corresponding tobramycin level in tracheal secretions. We conclude that substantial levels of antibiotics can be found frequently in respiratory tract specimens of patients receiving SDD. Therefore, the usual microbiological criteria used to assess respiratory tract infection may be unreliable in this setting and other criteria may be required. Follow-up of antibiotic serum levels is required, especially in patients with renal failure.

Unilateral diaphragmatic dysfunction in blunt chest trauma.

This study was undertaken to evaluate unilateral diaphragmatic dysfunction within ten days after blunt chest trauma. Thirty patients with unilateral chest injury, or predominantly one-sided injuries, were investigated in the supine position, under analgesia. Right and left hemidiaphragm displacement (DD) was measured, using digital subtraction radiography, during quiet and forced breathing. The diaphragmatic contribution to breathing was determined by rib cage and abdominal circumference measurement changes. In both breathing modes, DD of the injured side was lower than DD of the uninjured side (p less than 0.01, p less than 0.001). Six patients had complete diaphragmatic motionlessness. The inspired air volume due to diaphragmatic motion (Vab) was reduced when compared to normal subjects and Vab/VT ratio was always found to be less than 0.65. The degree of diaphragmatic dysfunction appeared related to injury location and is most severe in injuries of the lower chest which implies direct diaphragm muscle injury, although other mechanisms may be implicated. Diaphragmatic dysfunction can contribute to respiratory failure in these patients, and should be considered.