Between January 2005 and December 2008, we prospectively included 87 consecutive patients with a positive diagnosis of pulmonary thromboembolism developed on ICU admission and/or during ICU stay.
In our institution, the diagnosis of PE is usually suspected by the presence of tachypnea, dyspnea, pleuritic chest pain and hemoptysis. However in our ICU, most of the patients required sedation and mechanical ventilation and the diagnosis of PE is usually suspected in patients with un-explicated hypoxemia and/or shock and arterial hypotension. A medical committee of six ICU physicians examined prospectively all available data in order to classify patients according to the importance of clinical suspicion of pulmonary thromboembolism.
The diagnosis of PE is confirmed by a high-probability ventilation/perfusion (V/Q) scan[8
] or by spiral computed tomography (CT) scan showing one or more filling defects or obstruction in the pulmonary artery or its branches.[9
] The diagnosis was also confirmed when echocardiography showed a direct visualization of a thrombus in the pulmonary artery.[1
The V/Q scan and/or spiral CT scan are performed after correction of hemodynamic instability (using fluid resuscitation and/or catecholamine) and improvement of hypoxemia (using mechanical ventilation, high fraction of O2
). Massive PE is defined as the presence of hemodynamic instability: arterial hypotension and cardiogenic shock. Arterial hypotension is defined as a systolic arterial pressure <90 mm Hg or a drop in systolic arterial pressure of at least 40 mm Hg for at least 15 min. Shock is manifested by arterial hypotension and by tissue hypoperfusion and hypoxia, including an altered level of consciousness, oliguria, or cool, clammy extremities.[1
] During the study period, all the patients admitted to our ICU were classified into four groups. The first group includes all patients with confirmed PE. The second group includes 90 patients without clinical manifestations of PE (in this group, pulmonary thromboembolism is not suspected by our medical staff). From this group 90 patients were included in a random way and were analysed in this study.
The third group includes patients with suspected and not confirmed PE (all patients with normal spiral CT scan). The fourth group includes all patients with only DVTs without suspicion of PE.
Our department is a 22-bed medical surgical ICU in a teaching hospital of 510 beds that serves as a first-line medical center for an urban population of one million inhabitants and as a referral center for a larger population coming from south Tunisia. The total number of admissions in our unit is about 1200 per year.
For all included patients, a data entry form was designed to collect demographic, clinical and radiological data on admission and during ICU stay. The patient with a positive diagnosis of PEs, medical files were prospectively reviewed and the following data collected on hospital admission, ICU admission and during ICU stay: age, sex, heart rate, respiratory rate before mechanical ventilation, blood pressure, use of inotropic drugs, the presence of shock, cardiac arrest, fluid intake volume and urinary output. The systemic inflammatory response syndrome (SIRS)[10
] was also researched on admission and during ICU stay. Biochemical parameters measured on admission and during the ICU stay are arterial blood gases and acid-base status (pH and HCO3
), hemoglobin concentration etc.
In our study, the presence of arterial hypoxemia is defined by arterial oxygen saturation in room air ≤92%. In patients receiving mechanical ventilation, arterial hypoxemia is defined as a PaO2/FiO2 ratio <300.
Moreover, risk factors (immobility, recent surgery within 1 week, comorbid medical conditions, congestive heart failure, chronic obstructive pulmonary disease (COPD), cancer etc.) were also collected.
The use of preventive anticoagulant agents, the delay of development of PE and the clinical manifestations associated with the PE were also recorded for each patient.
On the other hand, chest X-ray findings and arterial blood gas values were recorded. Chest X-rays were analysed by a radiologist who is blinded to the patient's diagnosis. The ECG abnormalities were also recorded.
Due to nonavailability of echocardiography in either ICU or in hospital, only a few patients underwent. In fact, to perform an echocardiography, the patient will need to be transferred to some other hospital. Moreover, almost all patients included in our study have shock associated and/or acute respiratory distress with arterial oxygen tension/FiO2
ratio under 300. For these reasons, the echocardiography is rarely performed in our study. For each patient, clinically symptomatic DVTs were researched. Leg ultrasonography also known as Leg Doppler
is performed when DVT is suspected and when at the same time it is possible to perform Leg ultrasonography in association with spiral CT scan. Estimation of the clinical probability of PE is performed in all patients according to the two scoring systems: the Wells' score[11
] and the Geneva revised score,[12
] which have been tested prospectively and validated in large clinical trials. Massive PE is defined as the presence of hypotension or shock, whereas submassive PE is defined as stable hemodynamics in the presence of echocardiographic right ventricular (RV) dysfunction based on RV dilatation (end diastolic diameter >30 mm) or hypokinesia or abnormal movement of the interventricular septum with or without tricuspid regurgitation.[13
] Therapeutic agents given, either unfractionated heparin alone or thrombolytic agent, were noted. During the ICU stay, all complications were recorded: nosocomial infections,[14
] pneumonia, thrombocytopenia, gastrointestinal bleeding, cerebral hemorrhage and hematomas. For each patients, the number of organ failure[14
] was calculated on admission and on the day of diagnosis of PE. Moreover, for each patient the severity of illness was estimated with simplified acute physiology score (SAPS II) calculated within 24 h of admission,[15
] and according to the APACHE categorization at admission.[16
The number of patients who died in the ICU and in the hospital was recorded as the primary clinical outcome and patients were grouped accordingly into survivors and nonsurvivors.
Finally, in order to define predictive factors of pulmonary thromboembolism, the group of patients with confirmed PE was compared with the three other groups (without PE, patients with suspected and not confirmed PE and patients with only DVTs without suspicion of PE).
Categorical data are expressed in proportion and subgroups (survival and death; patients with and without PE) are analysed by the Chi-square test.
Continuous variables are expressed as means (± SD) and subgroups evaluated by Student t-test. Risk factors are evaluated in univariate analysis and by multivariate analysis by a multiple logistic stepwise regression procedure. Odds ratios are estimated from the b coefficients obtained, with respective 95% confidence intervals (CI 95%).