Sonographic Assessment of Intravascular Fluid Estimate (SAFE) Score by Using Bedside Ultrasound in the Intensive Care Unit
Table 1
Steps to follow while performing the ultrasound exam for the heart, lungs, IVC, and IJV. Score assignment with different findings during each exam.
Exam type
Exam method
Score assessment
Echo
(i) Place the patient in a supine position if no contraindications. (ii) Place a phased array transducer at the left sternal border 4-5th intercostal space (Figure 1). (iii) Obtain a long-axis view of the heart, note the cardiac function, and estimate the ejection fraction using the eyeballing method or the M-mode with the maximum systole and diastole measurements. (iv) Obtain a short-axis view of the hear, note the cardiac function, and estimate the ejection fraction. (v) Store the images for review.
Assign a score for the cardiac function as follows: (i) EF > 70%, hyperkinetic = −1 (ii) EF 50–70%, normal = 0 (iii) EF < 50%, hypokinetic = +1
Lung
(i) Place the patient in a supine position if no contraindications. (ii) Place a phased array or linear transducer perpendicular between two ribs in all 4 lung sectors, L1–4 on the right and left (Figure 2). (iii) Count the number of B-lines in each sector. (iv) Store the images for review.
Assign a score for lung water as follows: (i) Add the number of B-lines counted from all segments examined, and then divide by the number of segments examined for the average. (ii) Average < 1 B-lines = −1 (iii) Average 1-2 B-lines = 0 (iv) Average 3 or more B-lines = +1
IVC
(i) Place the patient in a supine position if no contraindications. (ii) Place a phased array or curvilinear transducer midline in the epigastric area to locate the IVC. (iii) Measure the IVC diameter just distal to the right hepatic vein, with the maximal and minimal diameter. (iv) Calculate the collapsibility index: ((maximal diameter − minimal diameter)/maximal diameter) × 100. (v) During spontaneous breathing, the maximal diameter will be during expiration and the minimal during inspiration, and the opposite is true during mechanical ventilation. (vi) Store the images for review.
Assign a score for the IVC as follows: (i) 2.5 cm in diameter and >50% variation in diameter during respiration = −1 (ii) 1.5–2.5 cm in diameter and <50% variation in diameter during respiration = 0 (iii) 2.5 cm in diameter and <50% variation in diameter during respiration = +1
IJV
(i) Place the head of the bed at 30 degrees if no contraindications. (ii) Place a linear transducer across the patient’ neck in the area of the cricoid cartilage. Hold the transducer with no pressure applied to the vein. (iii) Obtain the largest diameter image of the IJV. (iv) Measure the maximal and minimal diameter at the largest diameter point and the respiratory variation. (v) Calculate the collapsibility index: ((maximal diameter − minimal diameter)/maximal diameter) × 100. (vi) Store the images for review.
Assign a score for the IJV as follows: (i) 40% respiratory variation = −1 (ii) 20–40% respiratory variation = 0 (iii) 20% respiratory variation = +1
