Integrating structured point-of-care ultrasound into dengue fever management: A mini review and comprehensive clinical guide

Table 1 Correlation of inferior vena cava diameter and caval/distensibility indices with right atrial pressure, fluid responsiveness and fluid intolerance

IVC diameter (cm)	IVC inspiratory collapsibility or distensibility (%)	Right atrial pressure (mmHg)	Fluid responsiveness (to correlate with other features)	Fluid intolerance (to correlate with other features)
> 2.1	Collapsibility < 50	10-20	No	Possible
	Distensibility < 18
> 2.1	Collapsibility > 50	5-10	Possible (judicious fluid);	Possible
	Distensibility > 18
≤ 2.1	Collapsibility < 50	5-10	Possible (judicious fluid)	Possible
	Distensibility < 18
≤ 2.1	Collapsibility > 50	0-5	Yes	Unlikely
	Distensibility > 18

IVC: Inferior vena cava.

Table 2 Summary of potential issues during each phase of dengue fever and their relevant point-of-care ultrasound (POCUS) findings

Phase of disease	Potential issues	Expected finding(s)	POCUS characteristics
Febrile phase	Dehydration (normal-mildly raised serum lactate)	No signs of plasma leakage	Step 1: A-profile
			Step 2: Absence of free fluid
			Step 3: Normal GBWT
		Small IVC diameter	Step 4: Small IVC with > 50% collapsibility
		Underfilled ventricles	Step 5: Underfilled left ventricle
Critical phase	Plasma leakage (raised hematocrit and raised serum lactate)	Pulmonary interstitial edema	Step 1: B-profile
		Pleural effusion	Step 2: Presence of pleural effusion
		Free fluid in abdomen	Step 2: Presence of ascites
		Gallbladder wall thickening with pericholecystic fluid	Step 3: Gallbladder wall thickening (> 3 mm)
		Small IVC diameter	Step 4: Small IVC with > 50% collapsibility
		Pericardial effusion or myocardial dysfunction	Step 5: Presence of pericardial effusion or depressed left ventricular ejection fraction
	Bleeding (reducing hematocrit with raised serum lactate)	Normal or pulmonary interstitial edema	Step 1: A-profile or B-profile
		Free fluid in abdomen or normal finding	Step 2: Presence of ascites
		Gallbladder wall thickening with pericholecystic fluid or normal gallbladder	Step 3: Gallbladder wall thickening (> 3 mm)
		Normal or small IVC diameter	Step 4: Small IVC with > 50% collapsibility
	Dengue cardiomyopathy	Myocardial dysfunction	Step 5: Depressed left ventricular ejection fraction
Recovery phase	Reabsorption (systemic congestion with improving serum lactate)	Pulmonary interstitial edema	Step 1: B-profile
		Pleural effusion	Step 2: Presence of pleural effusion
		Free fluid in abdomen	Step 2: Presence of ascites
		Resolution of gallbladder wall thickening	Step 3: Resolution of gallbladder wall thickening
		Prominent IVC diameter	Step 4: Prominent IVC (> 2.1 cm) with < 50% collapsibility

Point-of-care ultrasound (POCUS) characteristics across different phases of dengue: Based on dengue POCUS protocol illustrated in Figure 2. GBWT: Gallbladder wall thickness; IVC: Inferior vena cava; POCUS: Point-of-care ultrasound.

Table 3 Common clinical scenarios in dengue fever and corresponding management strategies

Issues	Lung scan (step 1)	Free fluid (step 2)	Gallbladder (step 3)	IVC (step 4)	ECHO (step 5)	Hematocrit	Lactate	Management options (according to local guidelines)
Dehydration	Normal	No	Normal	< 2.1 cm Collapsibility > 50%	Normal	Normal or raised	Normal	Hydration (0.5-5 mL/kg/hour)
Plasma leakage (early)	Normal	Yes	Thickened	< 2.1 cm Collapsibility > 50%	Normal	Raised	Normal	Hydration (5-20 mL/kg/hour)
Plasma leakage (late)	Interstitial edema	Yes	Thickened	< 2.1 cm Collapsibility > 50%	Pericardial effusion	Raised	Raised	Hydration (5-20 mL/kg/hour)
Bleeding	Normal or interstitial edema	Yes	Normal or thickened	< 2.1cm Collapsibility varies	Normal	Reducing	Raised	Blood product transfusion
Reabsorption with systemic congestion	Interstitial edema	Yes	Normal or thickened	≥ 2.1cm Collapsibility < 50%	Normal	Varies	Normal	Stop hydration (consider diuresis)
Dengue cardiomyopathy/myocarditis	Interstitial edema	Yes	Normal or thickened	≥ 2.1cm Collapsibility < 50%	Reduced LVEF	Varies	Varies	Judicious hydration
Preexisting heart failure or renal failure	Interstitial edema	Varies	Varies	≥ 2.1cm Collapsibility varies	Reduced LVEF	Varies	Varies	Judicious hydration (consider diuresis)
Preexisting liver cirrhosis or nephrotic syndrome with hypoalbuminemia	Interstitial edema	Varies	Varies	< 2.1 cm Collapsibility > 50%	Normal	Varies	Varies	Hydration with colloid

IVC: Inferior vena cava; ECHO: Echocardiography; LVEF: Left ventricular ejection fraction.