Table 4. PoCUS use during COVID-19 pandemic.

DVT: Deep vein thrombosis; ARDS: Acute respiratory distress syndrome; ED: Emergency department; RT-PCR: Reverse transcription polymerase chain reaction; LUS: Lung ultrasound; IVC: Inferior vena cava; LUZ: Lung ultrasound Zaragoza; NPV: Negative predictive value; PPV: Positive predictive value; AUC: Area under the curve; RRI: Renal restrictive index; AKI: Acute kidney injury; PoCUS: Point-of-care ultrasound

Study name, year	Study type	PoCUS use	Study details/outcome	Conclusion
Alharthy et al., 2020 [59]	Prospective	- Detection of pulmonary changes due to COVID-19; screening for DVT occurrence	- 89 confirmed COVID-19 cases in ICU of age >18 years; with serious pneumonia resulting in respiratory failure - B-Lines, pleural line irregularities, and variable consolidations were observed by PoCUS - DVT identification by PoCUS in < 20% of patients at the bedside, while CT-proven PE was found in 1/4th of patients	- PoCUS can be used as an alternative modality for ICU-bound COVID-19 patients to diagnose and monitor pulmonary changes and DVT detection
Bianchi et al., 2021 [62]	Prospective, single center	- Early detection; diagnostic stratification of COVID-19 related pulmonary changes; correspondence with positive RT-PCR; also, used to detect false negativity of RT-PCR	- ED patients with high-risk exposure to known COVID-19 cases in the past 14 days; at least one clinical criterion suspicious for COVID-19 infection; any radiological findings of pneumonia; minimum one LUS examination in ED - Patient with age < 16 years; pregnancy; known SARS-CoV-2 infection were excluded - Atypical B or C lines, multiple consolidations; ARDS with bilateral multifocal B pattern with shattered areas of A pattern were observed by PoCUS	- PoCUS is effective in diagnostic stratification during COVID-19 outbreaks - Helps in identifying false positive RT-PCR results, in turn improving diagnostic sensitivity in ED
Bitar et al., 2021 [63]	Prospective, single center	- LUS and echocardiography were performed within 12 hours of ICU admission	- Patients with age > 18 years; high suspicion of COVID-19 - LUS signs under evaluation were bilateral B lines, bilateral diffuse irregularities of pleural line, absence of significant pleural effusion, presence of multiple subpleural consolidations of various sizes - Echocardiography findings included E/A, deceleration time (DT), E/e left ventricular filling pressure, inferior vena cava collapsibility	- PoCUS plays an essential role in the assessment and management of acute hypoxic pulmonary failure and circulatory failure in COVID-19 patients
Brenner et al., 2021 [64]	Retrospective	- To compare 12 field LUS data with RT-PCR, which was designated as a gold standard investigation for diagnosis of COVID-19	- 174 patients from two urban tertiary healthcare centers - Criteria under consideration included pleural irregularity, multiple discrete B lines, confluent B-lines, subpleural consolidations, and pleural effusions	- Lung PoCUS is a rapid and cost-effective tool and can be used as an alternative diagnostic tool in resource-limited setups where RT-PCR or CT chest are unavailable
Garcia-Ceberino et al., 2021 [69]	Retrospective	- PoCUS diagnosed proximal and distal DVT; CT pulmonary angiogram was done to rule out pulmonary embolism	- 87 patients across the general ward and ICU - Depending upon risk factors for DVT, a lower extremity ultrasound was performed to screen for the occurrence of DVT	- PoCUS helps detect DVT in COVID-19 patients; however, it cannot rule out the presence of pulmonary embolism
Chen et al., 2020 [70]	Prospective	- Two ultrasound fellowship-trained ED physicians performed IVC, focused cardiac ultrasound (FOCUS), and LUS exams in patients with high clinical suspicion of COVID-19	- 96 patients at ED of two academic hospitals - PoCUS discovered irregular pleural lines in 63.2% of the study population, bilateral confluence in 17.5%, and isolated B-lines in 53.1%, which were associated with a positive RT-PCR test and correlated with interleukin-6 levels - IVC ultrasound negatively correlated with expiratory pO2 and inspiratory pO2 - Expiratory diameter assessed by PoCUS positively correlated with Troponin I	- PoCUS exam was effective and impactful in the diagnosis, management, and prognosis of patients with confirmed or suspected COVID-19
Falster et al., 2021 [71]	Prospective, single center	- Daily LUS examination to assess for consolidations and pleural effusions	- 83 patients admitted to COVID-19 unit - Daily LUS findings were correlated with initial chest X-ray and clinical deterioration	- LUS can be a valuable tool in continuously monitoring COVID-19 patients - Although an initial LUS at admission might not be able to predict ICU admission, ARDS, or death, a rapid increase in Mongodi LUS scores may be suggestive of lung parenchymal, pleural disease progression requiring supplementary diagnostics and treatment
Galien et al., 2021 [65]	Observational	- To screen for DVT with proximal compression ultrasound of lower extremities	- 90 COVID-19 patients in a mixed medical and surgical ICU	- Compared to a complete duplex ultrasound of lower extremities, PoCUS can be a resource-sparing alternative for screening of DVT in COVID-19 patients
Gibbons et al., 2021 [72]	Prospective, single center	- Comparing radiological effectiveness of LUS with chest X-ray for diagnosing COVID-19 pneumonia	- 110 patients in an urban, academic, Level I ED with predefined signs and symptoms suggestive of COVID-19 for LUS	- LUS was found to be more radiologically sensitive than chest x-ray to diagnose viral/atypical pneumonia - Although LUS and chest X-ray both have low specificity, PoCUS can become a practical first-line imaging
Gonzalez et al., 2021 [73]	Observational	- Comparing right and left ventricular global longitudinal strain (GLS) with classic echo-doppler systolic function indices	- 30 COVID-19 patients in ICU - Echocardiography was performed on the day of admission, then on day three and day seven - Patients admitted for acute myocardial infarction or pulmonary embolism with a positive COVID-19 PCR swab test were excluded from study	- Ejection fraction for left ventricle (LVEF) and Left ventricular GLS are equivocally effective in assessing left ventricular systolic function - Right ventricular GLS weakly correlated with fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE) and not correlated in any way with tissue Doppler velocity of the basal free lateral wall (S’) for the right ventricle
Gracia et al., 2021 [74]	Prospective	- To analyze the prognosis of COVID-19 patients by LUZ-scale by LUS during the initial 72 hours of hospital admission	- 130 COVID-19 inpatients; a baseline LUZ score was established with primary endpoints being in-hospital death and/ or admission to ICU - Secondary outcomes like the length of hospital stay, escalation of medical treatment, and oxygen requirements were predicted using the baseline score	- Baseline LUZ score was predictive of severity of infection during hospital stay and, in turn, helps in early intervention and prevention of adverse outcomes
Gutsche et al., 2021 [75]	Prospective	- To assess PPV, NPV of LUS compared to RT-PCR and clinical findings	- 101 suspected COVID-19 inpatients of > 18 years old; non-pregnant patients with specific COVID-19 symptoms - LUS was performed within 48 hours of admission and compared with a prospective RT-PCR test - LUS scoring ranged from 0-3 in 12 lung regions bilaterally based on ultrasound findings - Patients with a score of 0 or 1 in all areas were classified as "LUS-COVID-negative." - Patients with a score of 2 or 3 in 1 out of 12 areas were classified as "LUS-COVID-positive."	- PPV and NPV of LUS were assessed to be 34.1% and 97.1% - Significantly higher NPV of LUS can depict its importance in ruling out COVID-19 infection
Kapoor et al., 2021 [76]	Prospective	- To screen for and diagnose lower extremity deep venous thrombosis on Days 1, 7, and 14	- 107 ICU COVID-19-positive patients confirmed by RT-PCR - The "2-region technique" was implemented for the diagnosis of DVT in the lower extremity, which involved compression of 1-2 cm area proximally and distally to (i) junction of great saphenous vein and common femoral vein extending to the confluence of superficial and deep femoral vein, (ii) posterior aspect of knee extending from proximal popliteal vein to confluence of calf vein	- PoCUS diagnosed 15.9% lower extremity DVT on Day 1, 6% on Day 7, and 4.1% on Day 14 - PoCUS is helpful in screening and diagnosing thromboembolic events during a pandemic, even in a setting with limited resources
Lieveld et al., 2021 [77]	Prospective	- Correlation of LUS findings; severity staging compared to CT severity score	- 114 RT-PCR confirmed COVID-19 patients - six lung fields were examined bilaterally in all patients in the ER, and a cutoff score of 12 was decided - Time to poor outcome was shorter in study group with LUS > 12 compared to that of LUS < 12	- Discriminative ability of one ultrasound was similar to that of the CT severity score in determining hospital admission (ward or ICU) or no admission with a statistically significant AUC of 0.83 (95% CI, 0.75-0.91)
Narinx et al., 2020 [78]	Retrospective	- To evaluate the accuracy, NPV, and PPV of lung PoCUS as compared to RT-PCR and CT	- 93 patients - Three BLUE points in each hemithorax were examined in either supine or semi-recumbent position for B-line pattern and thickening of the pleural line	- SN (93.3%) and NPV (94.1%) were significant compared to RT-PCR. But, SP (21.3%), PPV (19.2%), and accuracy (33.3%) were lower compared to RT-PCR - Significant values for SN (80.6%), SP (86.7%), NPV (95.6%), and accuracy (85.6%) were obtained, and a moderate value for PPV (54.5%) when compared to CT scan
Renberg et al., 2021 [67]	Observational	- To describe the pattern of RRI concerning AKI in COVID-19 patients	- 51 COVID-19 patients in ICU - Patients were examined in the ICU in supine or prone positions based on position favorable for maximum ventilation - Kidneys were examined bilaterally, and RRI was assessed on both sides	- Bedside PoCUS examination can measure RRI and, in turn, predict the severity of AKI in severely ill COVID-19 patients