Bedside Ultrasound-Guided Management of Sepsis
In adults with sepsis of unknown source, bedside point-of-care ultrasound (POCUS) should be performed immediately after initial clinical assessment to identify the infection source, with a structured protocol examining the chest, abdomen, pelvis, and inferior vena cava (IVC) for volume status—this approach achieves 73% sensitivity and 95% specificity for source identification and should be completed within 10 minutes. 1
Immediate POCUS Protocol for Source Identification
Perform a systematic head-to-toe ultrasound examination targeting the most common septic foci:
Chest examination (38.6% of septic foci): Scan for pneumonia (consolidation, air bronchograms), pleural effusion, and empyema using lung ultrasound with assessment of B-lines, consolidation patterns, and pleural fluid characteristics 2, 1
Abdomen examination (22% of septic foci): Evaluate for intra-abdominal collections, free fluid, bowel wall thickening, cholecystitis (gallbladder wall thickening >3mm, pericholecystic fluid, sonographic Murphy's sign), and hepatobiliary pathology 2, 1
Pelvis/genitourinary examination (20.5% of septic foci): Assess for hydronephrosis, pyonephrosis, bladder distension, pelvic collections, and gynecologic pathology in women of childbearing age 2, 3
Vascular examination: Scan central venous access sites for thrombophlebitis and perform bilateral lower extremity venous examination if pulmonary embolism is suspected 2
Performance Characteristics
POCUS-implemented diagnosis improves sensitivity by 25% compared to clinical assessment alone (73% vs 48%), with specificity of 95% versus 86% for clinical impression 1. Critically, POCUS diagnosis is obtained within 10 minutes, whereas standard workup identifies the source within 1 hour in only 21.9% of cases and within 3 hours in 52.8% 1.
Cardiac Ultrasound for Hemodynamic Assessment
Perform bedside cardiac ultrasound (BCU) to assess both left and right ventricular function, as septic cardiomyopathy occurs in a substantial proportion of septic patients:
Left Ventricular Assessment
Evaluate for LV systolic and diastolic dysfunction using parasternal long-axis and apical four-chamber views to guide inotropic therapy decisions 2
Recognize that excessive fluid resuscitation in the presence of LV dysfunction will aggravate adverse consequences and worsen outcomes 2
Look for apical ballooning syndrome (Takotsubo cardiomyopathy), which can present in ICU patients with sepsis and typically resolves spontaneously 2
Right Ventricular Assessment
Screen for RV dysfunction, which occurs in up to 30% of septic patients by assessing RV size relative to LV, RV wall motion, and interventricular septal position 2
Evaluate RV to LV end-diastolic volume ratio in subcostal short-axis view; RV dilation with RV:LV ratio >1:1 suggests significant RV dysfunction 2
Early identification of RV dysfunction helps guide fluid management, inotrope selection, and vasopressor therapy to minimize further dysfunction 2
IVC Assessment for Volume Status
Measure IVC diameter and respiratory variation to guide fluid resuscitation decisions:
Obtain subcostal long-axis view of the IVC approximately 2cm from the right atrial junction 4
IVC collapsibility >50% with inspiration suggests fluid responsiveness and supports additional fluid boluses 4, 5
IVC diameter >2cm with <50% respiratory variation suggests adequate or excessive volume status and should prompt reassessment before further fluid administration 4, 5
Integrate IVC findings with clinical examination (capillary refill, skin mottling, peripheral pulses, mental status, urine output) to assess tissue perfusion 2, 4
Procedure Guidance
Use ultrasound guidance for all invasive procedures in septic patients to enhance safety and success rates:
Central venous cannulation: Real-time ultrasound guidance reduces complications and improves first-pass success 5, 6
Thoracentesis and chest tube placement: Ultrasound identifies optimal entry site, confirms fluid presence, and avoids solid organs 5, 6
Paracentesis and abscess drainage: Ultrasound localizes fluid collections and guides safe needle/catheter placement 5, 6
Integration with Standard Workup
Do not delay CT imaging when POCUS is equivocal or negative:
If POCUS does not identify a source and clinical suspicion remains high, proceed immediately to CT chest/abdomen/pelvis with IV contrast, which has 81.82% positive predictive value for identifying septic foci 2, 3
For suspected urosepsis, if ultrasound shows no hydronephrosis or pyonephrosis but clinical suspicion persists, obtain contrast-enhanced CT, as major abnormalities are found in 32% of cases and 13% require urological intervention 2, 3
Never rely on chest radiography alone, as sensitivity for pneumonia in severe sepsis is only 58% 7
Critical Pitfalls to Avoid
Do not delay antimicrobial therapy to complete imaging: Antibiotics must be administered within 1 hour of sepsis recognition, immediately after blood cultures are obtained 2, 7
Do not use POCUS as a substitute for comprehensive imaging when the diagnosis remains unclear: POCUS is an adjunct that accelerates diagnosis but does not replace CT when needed 2, 1
Do not over-resuscitate based on IVC findings alone: Integrate multiple parameters including cardiac function, clinical perfusion markers, and lactate trends 2, 4
Recognize that POCUS requires adequate training: The Critical Care Medicine guidelines recommend these assessments for all levels of training, but competency must be established 2
Monitoring Response to Therapy
Perform serial POCUS examinations to assess response to interventions:
Reassess cardiac function after fluid boluses to detect development of pulmonary edema or worsening ventricular function 2, 5
Re-evaluate IVC after each 500mL fluid bolus to guide ongoing resuscitation 4, 5
Monitor for interval development of new complications (pleural effusions, ascites, pericardial effusion) 5, 6