Association between time to surgery and hospital mortality in patients with community-acquired limb necrotizing fasciitis: an 11-year multicenter retrospective cohort analysis.

BACKGROUND: Necrotizing fasciitis (NF) is a rare but potentially life-threatening soft tissue infection. The objective of this study was to assess the association between timely surgery within 6 h and hospital mortality in patients with limb NF, and to describe the trends in patients with NF, time to surgery and standardized mortality ratio (SMR) over 11 years. METHODS: This was a multicenter, retrospective cohort study of all intensive care unit patients who had emergency surgery within 24 h of hospitalization for limb NF between April 1, 2008 and March 31, 2019 in Hong Kong. Timely surgery was defined as the first surgical treatment within 6 h of initial hospitalization. Appropriate antibiotics were achieved if the patient was given antibiotic(s) for all documented pathogens prior to or on day of culture results. The primary outcome was hospital mortality. RESULTS: There were 495 patients (median age 62 years, 349 (70.5%) males) with limb NF treated by surgery within 24 h of hospitalization over the 11 years. Appropriate antibiotic(s) were used in 392 (79.2%) patients. There were 181 (36.5%) deaths. Timely surgery was not associated with hospital mortality (Relative Risk 0.89, 95% CI: 0.73 to 1.07) but admission year, advanced age, higher severity of illness, comorbidities, renal replacement therapy, vasopressor use, and type of surgery were significant predictors in the multivariable model. There was an upward trend in NF diagnosis (1.9 cases/year, 95% CI: 0.7 to 3.1; P < 0.01; R2 = 0.60) but there was no downward trend in median time to surgery (-0.2 h/year, 95% CI: -0.4 to 0.1; P = 0.16) or SMR (-0.02/year, 95% CI: -0.06 to 0.01; P = 0.22; R2 = 0.16). CONCLUSIONS: Among patients operated within 24 h, very early surgery within 6-12 h was not associated with survival. Increasing limb NF cases were reported each year but mortality remained high despite a high rate of appropriate antibiotic use and timely surgical intervention.

Population sepsis incidence, mortality, and trends in Hong Kong between 2009-2018 using clinical and administrative data.

BACKGROUND: Sepsis surveillance using electronic health record (EHR)-based data may provide more accurate epidemiologic estimates than administrative data, but experience with this approach to estimate population-level sepsis burden is lacking. METHODS: This was a retrospective cohort study including all adults admitted to publicly-funded hospitals in Hong Kong between 2009-2018. Sepsis was defined as clinical evidence of presumed infection (clinical cultures and treatment with antibiotics) and concurrent acute organ dysfunction (≥2 point increase in baseline SOFA score). Trends in incidence, mortality, and case fatality risk (CFR) were modelled by exponential regression. Performance of the EHR-based definition was compared with 4 administrative definitions using 500 medical record reviews. RESULTS: Among 13,550,168 hospital episodes during the study period, 485,057 (3.6%) had sepsis by EHR-based criteria with 21.5% CFR. In 2018, age- and sex-adjusted standardized sepsis incidence was 759 per 100,000 (relative +2.9%/year [95%CI 2.0, 3.8%] between 2009-2018) and standardized sepsis mortality was 156 per 100,000 (relative +1.9%/year [95%CI 0.9,2.9%]). Despite decreasing CFR (relative -0.5%/year [95%CI -1.0, -0.1%]), sepsis accounted for an increasing proportion of all deaths (relative +3.9%/year [95%CI 2.9, 4.9%]). Medical record reviews demonstrated that the EHR-based definition more accurately identified sepsis than administrative definitions (AUC 0.91 vs 0.52-0.55, p < 0.001). CONCLUSIONS: An objective EHR-based surveillance definition demonstrated an increase in population-level standardized sepsis incidence and mortality in Hong Kong between 2009-2018 and was much more accurate than administrative definitions. These findings demonstrate the feasibility and advantages of an EHR-based approach for widescale sepsis surveillance.

Veno-arterial extracorporeal membrane oxygenation with concomitant Impella versus concomitant intra-aortic-balloon-pump for cardiogenic shock.

INTRODUCTION: The intra-aortic balloon pump (IABP) and Impella are left ventricular unloading devices with peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO) in place and later serve as bridging therapy when VA-ECMO is terminated. We aimed to determine the potential differences in clinical outcomes and rate of complications between the two combinations of mechanical circulatory support. METHODS: This was a retrospective, single institutional cohort study conducted in the intensive care unit (ICU) of Queen Elizabeth Hospital, Hong Kong. Inclusion criteria included all patients aged ⩾18 years, who had VA-ECMO support, and who had left ventricular unloading by either IABP or Impella between January 1, 2018 and October 31, 2020. Patients <18 years old, with central VA-ECMO, who did not require left ventricular unloading, or who underwent surgical venting procedures were excluded. The primary outcome was ECMO duration. Secondary outcomes included length of stay (LOS) in the ICU, hospital LOS, mortality, and complication rate. RESULTS: Fifty-two patients with ECMO + IABP and 14 patients with ECMO + Impella were recruited. No statistically significant difference was observed in terms of ECMO duration (2.5 vs 4.6 days, p = 0.147), ICU LOS (7.7 vs 10.8 days, p = 0.367), and hospital LOS (14.8 vs 16.5 days, p = 0.556) between the two groups. No statistically significant difference was observed in the ECMO, ICU, and hospital mortalities between the two groups. Specific complications related to the ECMO and Impella combination were also noted. CONCLUSIONS: Impella was not shown to offer a statistically significant clinical benefit compared with IABP in conjunction with ECMO. Clinicians should be aware of the specific complications of using Impella.

Comparing the outcomes of bedside percutaneous VA-ECMO decannulation by ProGlide and Manta in a high-ECMO-volume center in Hong Kong.

BACKGROUND: The use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) decannulation with different percutaneous closure devices has been increasing. At our center, ProGlide devices have been used since November 2018, and Manta devices became an alternative since March 2020. This study aimed to compare the success and complication rates and the clinical outcomes of ProGlide and Manta devices for VA-ECMO decannulation after arteriotomy wound closure. METHODS: We retrospectively reviewed the results of bedside VA-ECMO decannulation between November 2018 and June 2021. Patients with VA-ECMO who could be bridged to recovery were recruited and divided into the ProGlide or Manta group based on the closure device used. Procedure time, amount of blood loss, amount of blood products transfused, and use of vasoactive medications during the procedure were documented. Clinical examination and Doppler ultrasound were performed to detect any complications. RESULTS: After the closure technique, ProGlide was used in 44 patients and Manta was used in 13. There was no significant difference in the success rate between the ProGlide and Manta groups (86.4% vs. 100%). Amount of blood loss was greater in the ProGlide group than in the Manta group (290 [100-400] ml vs. 50 [50-100] ml), and more patients in the ProGlide group required an increased dose of inotropes during the procedure (59.1% vs. 15.4%), but the transfusion requirement was similar between the two groups. CONCLUSIONS: The success rate of hemostasis using arteriotomy wound closure during VA-ECMO decannulation was similar between the two devices.

Glycemic control in critically ill patients with or without diabetes.

BACKGROUND: Early randomized controlled trials have demonstrated the benefits of tight glucose control. Subsequent NICE-SUGAR study found that tight glucose control increased mortality. The optimal glucose target in diabetic and nondiabetic patients remains unclear. This study aimed to evaluate the relationship between blood glucose levels and outcomes in critically ill patients with or without diabetes. METHODS: This was a retrospective analysis of the eICU database. Repeat ICU stays, ICU stays of less than 2 days, patients transferred from other ICUs, those with less than 2 blood glucose measurements, and those with missing data on hospital mortality were excluded. The primary outcome was hospital mortality. Generalised additive models were used to model relationship between glycemic control and mortality. Models were adjusted for age, APACHE IV scores, body mass index, admission diagnosis, mechanical ventilation, and use of vasopressor or inotropic agents. RESULTS: There were 52,107 patients in the analysis. Nondiabetes patients exhibited a J-shaped association between time-weighted average glucose and hospital mortality, while this association in diabetes patients was right-shifted and flattened. Using a TWA glucose of 100 mg/dL as the reference value, the adjusted odds ratio (OR) of TWA glucose of 140 mg/dL was 3.05 (95% confidence interval (CI) 3.03-3.08) in nondiabetes and 1.14 (95% CI 1.08-1.20) in diabetes patients. The adjusted OR of TWA glucose of 180 mg/dL were 4.20 (95% CI 4.07-4.33) and 1.49 (1.41-1.57) in patients with no diabetes and patients with diabetes, respectively. The adjusted ORs of TWA glucose of 80 mg/dL compared with 100 mg/dL were 1.74 (95% CI 1.57-1.92) in nondiabetes and 1.36 (95% CI 1.12-1.66) in patients with diabetes. The glucose ranges associated with a below-average risk of mortality were 80-120 mg/dL and 90-150 mg/dL for nondiabetes and diabetes patients, respectively. Hypoglycemia was associated with increased hospital mortality in both groups but to a lesser extent in diabetic patients. Glucose variability was positively associated with hospital mortality in nondiabetics. CONCLUSIONS: Time-weighted average glucose, hypoglycemia, and glucose variability had different impacts on clinical outcomes in patients with and without diabetes. Compared with nondiabetic patients, diabetic patients showed a more blunted response to hypo- and hyperglycemia and glucose variability. Glycemic control strategies should be reconsidered to avoid both hypoglycemia and hyperglycemia.

Case report of successful peripheral veno-arterial extracorporeal membrane oxygenation in a patient with chronic type B aortic dissection.

A case report of successful application of peripheral veno-arterial extracorporeal membrane oxygenation in a patient with chronic type B aortic dissection and myocardial stunning to bridge to recovery was presented. Good outcomes from the application of peripheral veno-arterial extracorporeal membrane oxygenation in aortic dissection have rarely been reported, and the considerations of starting veno-arterial extracorporeal membrane oxygenation in this situation were seldom discussed. The orthodox that peripheral veno-arterial extracorporeal membrane oxygenation is an absolute contraindication for initiation of peripheral veno-arterial extracorporeal membrane oxygenation should be challenged. With proper planning and real-time transesophageal echocardiography-guided cannulation, peripheral veno-arterial extracorporeal membrane oxygenation is possibly beneficial. The considerations and echocardiography-guided techniques would be discussed in this report.

Real-time ultrasound-guided bedside closure of arteriotomy wound using MANTA closure device during venoarterial extracorporeal membrane oxygenation decannulation.

Percutaneous closure of arteriotomy wound during peripheral venoarterial extracorporeal membrane oxygenation decannulation was shown to be safe and allow earlier mobilization. The new MantaTM vascular closure device (Essential Medical), designed for the closure of arterotomy wound created by large-bore vascular sheaths up to 25Fr during endovascular catheterization procedures, was reported to be applicable in venoarterial extracorporeal membrane oxygenation decannulation. In this article, we would like to share our experience of using real-time ultrasound guidance to ensure the safe application of Manta during bedside venoarterial extracorporeal membrane oxygenation decannulation.

One-year experience of bedside percutaneous VA-ECMO decannulation in a high-ECMO-volume center in Hong Kong.

BACKGROUND: When veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support can be terminated, open repair of arteriotomy wounds in operating theaters is the standard of practice. Comparable outcomes by percutaneous decannulation using different closure devices have been reported. However, transport of the critically- ill, man-power and timeslots of operating theaters could be saved if decannulation was performed at bedside. METHOD: Bedside percutaneous arteriotomy wound closure became our default method of decannulation since November 2018. We reviewed our 1-year data to evaluate if such practice could be safely adopted in a local high-ECMO-volume center. RESULTS: Between November 2018 and October 2019, 25 patients had their VA-ECMO terminated at the bedside. Twenty-one patients (84%) had successful decannulation. For those who failed, emergency open repair resulted in no additional complications. Two ProGlide devices were used in 15 (71.4%) patients and three were used in 6 (28.6%) patients. The procedure time was 27 (15-45) min. The median blood loss was 300 mL (250-400). Minor complications were found in 4 (19.1%) patients, including two arterial clot formation, one pseudoaneurysm and one wound infection. There were no other major complications. CONCLUSION: Our 1-year experience showed that percutaneous bedside VA-ECMO decannulation was feasible to commence in a local large-ECMO-volume center.

Preoxygenation before intubation in adult patients with acute hypoxemic respiratory failure: a network meta-analysis of randomized trials.

BACKGROUND: Patients with acute hypoxemic respiratory failure are at risk for life-threatening complications during endotracheal intubation. Preoxygenation might help reduce the risk of hypoxemia and intubation-related complications. This network meta-analysis summarizes the efficacy and safety of preoxygenation methods in adult patients with acute hypoxemic respiratory failure. METHODS: We searched PubMed, EMBASE, and the Cochrane Library Central Register of Controlled Trials through April 2019 for randomized controlled trials (RCT) that studied the use of conventional oxygen therapy (COT), high-flow nasal cannula (HFNC), noninvasive ventilation (NIV), and HFNC and NIV as preoxygenation before intubation in patients with acute hypoxemic respiratory failure. Citations' screening, study selection, data extraction, and risk of bias assessment were independently performed by two authors. The primary outcome was the lowest SpO2 during the intubation procedure. RESULTS: We included 7 RCTs (959 patients). Patients preoxygenated with NIV had significantly less desaturation than patients treated with COT (mean difference, MD 5.53, 95% CI 2.71, 8.34) and HFNC (MD 3.58, 95% CI 0.59, 6.57). Both NIV (odds ratio, OR 0.43, 95% CI 0.21, 0.87) and HFNC (OR 0.49, 95% CI 0.28, 0.88) resulted in a lower risk of intubation-related complications than COT. There were no significant mortality differences among the use of NIV, HFNC, COT, and HFNC and NIV during preoxygenation. CONCLUSIONS: In adult patients with acute hypoxemic respiratory failure, NIV is a safe and probably the most effective preoxygenation method.

Comparison of COVID-19 with influenza A in the ICU: a territory-wide, retrospective, propensity matched cohort on mortality and length of stay.

OBJECTIVES: Direct comparisons between COVID-19 and influenza A in the critical care setting are limited. The objective of this study was to compare their outcomes and identify risk factors for hospital mortality. DESIGN AND SETTING: This was a territory-wide, retrospective study on all adult (≥18 years old) patients admitted to public hospital intensive care units in Hong Kong. We compared COVID-19 patients admitted between 27 January 2020 and 26 January 2021 with a propensity-matched historical cohort of influenza A patients admitted between 27 January 2015 and 26 January 2020. We reported outcomes of hospital mortality and time to death or discharge. Multivariate analysis using Poisson regression and relative risk (RR) was used to identify risk factors for hospital mortality. RESULTS: After propensity matching, 373 COVID-19 and 373 influenza A patients were evenly matched for baseline characteristics. COVID-19 patients had higher unadjusted hospital mortality than influenza A patients (17.5% vs 7.5%, p<0.001). The Acute Physiology and Chronic Health Evaluation IV (APACHE IV) adjusted standardised mortality ratio was also higher for COVID-19 than influenza A patients ((0.79 (95% CI 0.61 to 1.00) vs 0.42 (95% CI 0.28 to 0.60)), p<0.001). Adjusting for age, PaO2/FiO2, Charlson Comorbidity Index and APACHE IV, COVID-19 (adjusted RR 2.26 (95% CI 1.52 to 3.36)) and early bacterial-viral coinfection (adjusted RR 1.66 (95% CI 1.17 to 2.37)) were directly associated with hospital mortality. CONCLUSIONS: Critically ill patients with COVID-19 had substantially higher hospital mortality when compared with propensity-matched patients with influenza A.

Levosimendan's effect on venoarterial extracorporeal membrane oxygenation weaning.

BACKGROUND: Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) provides temporary haemodynamic support in refractory cardiogenic shock. Recent retrospective studies on levosimendan on V-A ECMO weaning had conflicting results. This study aimed to determine the association between levosimendan on V-A ECMO weaning success in a tertiary centre in Hong Kong. METHODS: This retrospective study was conducted in an intensive care unit in Hong Kong. All adult patients requiring V-A ECMO from January 2016 to September 2020 were included. Patients who were given levosimendan were compared to patients who were not, on rates of successful V-A ECMO weaning. The groups were also compared after propensity matching based on covariates closely associated with the use of levosimendan. RESULTS: A total of 119 patients were included in the study, with 38 in the levosimendan group and 81 in the non-levosimendan group. Patients treated with levosimendan trended towards improved weaning success, but the difference was not statistically significant (63% vs 53%, p = 0.404). In the propensity-matched groups, there was no difference in weaning success (odds ratio 1.00, 95% CI 0.23-8.00). The levosimendan group was associated with lower vasopressor requirement, lower lactate levels, and more significant drop in lactate in the first 2 days of V-A ECMO. The levosimendan group had longer ECMO duration. There was no difference in other secondary outcomes including mortality, length of stay in ICU and hospital and duration of mechanical ventilation. There was no difference in the rate of ventricular arrhythmias. CONCLUSION: Levosimendan did not improve V-A ECMO weaning success in our cohort with refractory cardiogenic shock.

Steroid, ascorbic acid, and thiamine in adults with sepsis and septic shock: a systematic review and component network meta-analysis.

To assess the effect from individual component in combinations of steroid, ascorbic acid, and thiamine on outcomes in adults with sepsis and septic shock with component network meta-analysis (NMA). We searched PubMed, EMBASE, and the Cochrane Library Central Register of Controlled Trials from 1980 to March 2021 for randomized controlled trials (RCT) that studied the use of glucocorticoid, fludrocortisone, ascorbic acid, and thiamine in patients with sepsis and septic shock. Citations screening, study selection, data extraction, and risk of bias assessment were independently performed by two authors. The primary outcome was short-term mortality. Secondary outcomes were longer-term mortality, time to resolution of shock and duration of mechanical ventilation. Thirty-three RCTs including 9898 patients presented on short-term mortality. In additive component NMA, patients on ascorbic acid alone (RR 0.74, 95% CI 0.57-0.97) or the combination of glucocorticoid and fludrocortisone (RR 0.89, 95% CI 0.80-0.99) had lower short-term mortality, but only the latter was associated with improved long-term mortality (RR 0.89, 95% CI 0.82-0.98). The use of glucocorticoid or the combination of glucocorticoid, ascorbic acid and thiamine hastened resolution of shock. Component NMA showed glucocorticoid (MD - 0.96, 95% CI - 1.61 to - 0.30) but not ascorbic acid or thiamine shortened the time to resolution of shock. Glucocorticoid shortened the duration of mechanical ventilation (MD - 1.48, 95% CI - 2.43 to - 0.52). In adults with sepsis and septic shock, the combination of glucocorticoid and fludrocortisone improved short-term and longer-term mortality. Glucocorticoid shortened the time to resolution of shock and duration of mechanical ventilation. There was no strong evidence supporting the routine use of thiamine and ascorbic acid, but they were associated with minimal adverse effects.

Bleeding, thrombosis and transfusion in patients on ECMO: A retrospective study in a tertiary center in Hong Kong.

PURPOSE: Use of anticoagulation in patients on ECMO, especially in Chinese, has always been difficult. This study aimed to review the incidence of bleeding, thrombosis, and transfusion requirement in Chinese ECMO patients and to identify risk factors for bleeding complications. MATERIALS AND METHODS: This was a retrospective observational study of a tertiary hospital from 2010 to 2018. Patients aged ⩾18 years who received ECMO were included. The primary outcome was incidence of bleeding. Secondary outcomes included ICU mortality, hospital mortality, and length of the ICU and hospital stay. RESULTS: Of the 130 patients, 55(42.3%) had at least one bleeding events and thrombosis occurred in 37(28.5%). A lower fibrinogen level (adjusted OR 0.56 (0.36-0.86), p = 0.009), bloodstream infection (adjusted OR 2.76 (1.01-7.53), p = 0.047) and longer duration on ECMO (adjusted OR 1.14 (1.02-1.27), p = 0.018) were independently associated with occurrence of bleeding. APTT (adjusted OR 0.99 (0.97-1.01), p = 0.370) and platelet count (adjusted OR 1.00 (0.98-1.01), p = 0.632) were not statistically significant risk factors for bleeding events. CONCLUSIONS: Bleeding and thrombosis were common complications in Chinese patients receiving ECMO. Hypofibrinogenemia and bloodstream infection, but not APTT nor platelet counts, were independent risk factors for bleeding events.

Enhanced vascular assessment by ultrasound using microbubble contrast after percutaneous decannulation of peripheral veno-arterial extracorporeal membrane oxygenation.

Termination of peripheral veno-arterial extracorporeal membrane oxygenation support by managing the arteriotomy wound using a percutaneous closure device was reported successful and effective. However, careful assessment by clinical examination and also ultrasound Doppler assessment of the lower limb vasculature after closure is of paramount importance. Complications including pseudoaneurysm, arterial stenosis, and acute thrombosis are not uncommon. In this case report, commercial microbubbles were used as ultrasound contrast to enhance the image quality for better vascular ultrasound and Doppler assessment after veno-arterial extracorporeal membrane oxygenation percutaneous decannulation. A peudoaneurysm was revealed after microbubble injection, which would otherwise be missed.

Positive fluid balance and mortality in adult patients treated with extracorporeal membrane oxygenation: A retrospective study.

BACKGROUND: Intravenous fluid is important for resuscitation and maintenance of circuit flow in patients with extracorporeal membrane oxygenation, but fluid overload is widely recognized as detrimental in critically ill patients. This study aimed to evaluate the association between positive fluid balance and outcomes in adult patients treated with extracorporeal membrane oxygenation. METHODS: This was a retrospective observational study of a tertiary hospital from October 2010 to January 2018. Patients aged ≥18 years who received extracorporeal membrane oxygenation for ≥48 h were included. The fluid balance was determined as the difference between fluid intake and fluid output, and the cumulative fluid balance was calculated as the sum of these values on the preceding days. The primary outcome was hospital mortality. RESULTS: Of the 123 included extracorporeal membrane oxygenation episodes, 79 were venovenous extracorporeal membrane oxygenation. The hospital mortality rate was 31.7%. Seventy-eight patients underwent continuous renal replacement therapy during their extracorporeal membrane oxygenation course. Non-survivors had a greater cumulative fluid balance (p≤0.001) and a lower cumulative fluid output (p = 0.006) than survivors on day 7. Fluid intake was not significantly different between survivors and non-survivors (p = 0.583). In the multivariate analysis, the cumulative fluid balance (per litre) on day 7, but not on day 3, was associated with increased hospital mortality (adjusted OR: 1.17, 95% CI: 1.06-1.29, p = 0.001). CONCLUSIONS: In adult patients treated with extracorporeal membrane oxygenation, a higher positive cumulative fluid balance on day 7 was associated with increased hospital mortality. The association between positive fluid balance and mortality was mainly influenced by lower fluid output rather than an increase in fluid intake.

Simulation training on bedside veno-arterial extracorporeal membrane oxygenation decannulation.

Veno-arterial extracorporeal membrane oxygenation is a form of mechanical circulatory support for patients with refractory decompensated heart failure. Blood is drawn from a large vein and pumped back to a large artery, usually a femoral artery through large bore catheters. When the heart recovers, the extracorporeal membrane oxygenation support can be terminated and the catheters are decannulated. The bleeding at the venous side can be controlled by prolonged compression; however, the arteriotomy wound needs to be repaired. Conventionally, the arteriotomy wounds require open vascular repair in the operating theater. The novel application of percutaneous vascular closure devices, which have been commonly used in vascular operations and percutaneous structural heart interventions, could be applied for closure of arteriotomy wounds at the bedside after extracorporeal membrane oxygenation support. The post-close ProGlide (Abbott Vascular) technique was shown to be safe and could potentially save time and manpower. The wounds are much smaller as compared with the conventional open repair and potentially, the chance of wound infection can be reduced. However, the success of percutaneous bedside closure requires careful prior planning and technique training. Backup plans with vascular surgeons' standby are essential in case of failure of closure. Staffs in the extracorporeal membrane oxygenation centers need to be familiar with the preparation, the procedure as well as the device application technique for successful percutaneous closure. The long learning curve and the limited case load mean that such skills are best trained by simulation scenarios. This article described how this new technique and the team logistics can be trained by simulation.

Confirming Distal Perfusion Catheter Position by Micro-bubbles in Patients on Peripheral Venoarterial Extracorporeal Membrane Oxygenation.

Distal perfusion catheter (DPC) is commonly employed to prevent lower limb ischemia in patient put on peripheral venoarterial extracorporeal membrane oxygenation. Confirming its proper position is important but technically difficult by bedside ultrasound. We describe in this article a novel method to use micro-bubble ultrasound enhancing agents, which are commonly used for contrast echocardiography studies, to confirm DPC position at the bedside. The sequential appearance of the micro-bubbles in the popliteal artery and then popliteal vein by ultrasound after injection through the side port of the DPC confirms the proper DPC position.