Perioperative lower limb venous haemodynamics in patients under general anaesthesia †

Pathophysiological Processes Underlying the High Prevalence of Deep Vein Thrombosis in Critically Ill COVID-19 Patients

Coronavirus disease 2019 (COVID-19) predisposes to deep vein thrombosis (DVT) and pulmonary embolism (PE) particularly in mechanically ventilated adults with severe pneumonia. The extremely high prevalence of DVT in the COVID-19 patients hospitalized in the intensive care unit (ICU) has been established between 25 and 84% based on studies including systematic duplex ultrasound of the lower limbs when prophylactic anticoagulation was systematically administrated. DVT prevalence has been shown to be markedly higher than in mechanically ventilated influenza patients (6–8%). Unusually high inflammatory and prothrombotic phenotype represents a striking feature of COVID-19 patients, as reflected by markedly elevated reactive protein C, fibrinogen, interleukin 6, von Willebrand factor, and factor VIII. Moreover, in critically ill patients, venous stasis has been associated with the prothrombotic phenotype attributed to COVID-19, which increases the risk of thrombosis. Venous stasis results among others from immobilization under muscular paralysis, mechanical ventilation with high positive end-expiratory pressure, and pulmonary microvascular network injuries or occlusions. Venous return to the heart is subsequently decreased with increase in central and peripheral venous pressures, marked proximal and distal veins dilation, and drops in venous blood flow velocities, leading to a spontaneous contrast “sludge pattern” in veins considered as prothrombotic. Together with endothelial lesions and hypercoagulability status, venous stasis completes the Virchow triad and considerably increases the prevalence of DVT and PE in critically ill COVID-19 patients, therefore raising questions regarding the optimal doses for thromboprophylaxis during ICU stay.

Development of a postoperative occlusive thrombus at the site of an implanted inferior vena cava filter: A case report

RATIONALE

Although an inferior vena cave (IVC) filter is placed to prevent fatal pulmonary embolism (PE), several complications associated with an IVC filter have been reported. We describe a case with symptomatic PE, of which the origin was an occlusive IVC thrombus that developed from the placement of an IVC filer after a laparoscopy-assisted total gastrectomy (LATG).

PATIENT CONCERNS

A 71-year-old man underwent LATG under general anesthesia alone. He had an IVC filter implanted 13 years ago. An intravenous infusion of unfractionated heparin was substituted for the discontinuation of oral warfarin four days before the surgery. The proposed operation was performed and took a total of 404 minutes including the total duration of pneumoperitoneum that took 374 minutes. After the surgery, he experienced severe shivering reactions that required frequent bolus infusions of antihypertensive drugs. On the third postoperative day, he complained of dyspnea after taking a short walk, and subsequently lost consciousness. While he spontaneously recovered without requiring any resuscitation efforts, we performed computed tomography (CT) examination for suspected PE.

DIAGNOSES

The CT showed that a massive thrombus was occupying the intravenous space from the IVC filter to the left common iliac vein with several embolic defects in the peripheral pulmonary arteries present.

INTERVENTIONS

An anticoagulant therapy was established with 10 mg of oral apixaban given twice a day for the first four days, followed by a reduction to 5 mg.

OUTCOMES

On the 17th postoperative day, an ultrasound vascular examination confirmed the complete disappearance of deep venous thrombus (DVT).

LESSONS

As an IVC filter itself may be a potential source of DVT, we should carefully manage patients with a previously implanted IVC filter throughout the perioperative period.

Lower limb gangrene postcardiac surgery

A 67-year-old gentleman presented with a 1-day history of left foot pain. He had recently been discharged following a coronary artery bypass graft; during the admission, he had received an intravenous heparin infusion. Examination revealed black-purple discolouration of the first and second digits of the left foot with pitting oedema to the level of the knee. The posterior tibial and dorsalis pedis pulses were both shown to be patent. A new thrombocytopenia was noted. Ultrasound imaging revealed multiple deep vein thrombosis. The history of recent heparin exposure coupled with venous gangrene secondary to deep vein thrombosis was consistent with heparin-induced thrombocytopenia. He was treated acutely with intravenous danaparoid and later with warfarin. There was complete resolution of the venous gangrene at 1 month follow-up.

Effects of epidural-and-general anesthesia combined versus general anesthesia alone on femoral venous flow during laparoscopic cholecystectomy

BACKGROUND AND OBJECTIVE

The pneumoperitoneum has been shown to decrease femoral blood flow, resulting in venous stasis. We analyzed the effects of the pneumoperitoneum and epidural analgesia on femoral vein diameter and the peak flow rate of femoral vein during laparoscopic cholecystectomy.

PATIENTS AND METHODS

Forty patients were randomly allocated to receive either combined epidural analgesia (EA) and general anesthesia (GA) (group EA/GA) or GA alone (group GA). Laparoscopic cholecystectomy was the standard operation for the selected patients. Then, 10 mL of 1% lidocaine in group EA/GA or physiologic serum in group GA was injected via epidural catheter. Peak flow rates (PFRs) of femoral vein cross-sectional areas (CSAs) were measured from the right femoral vein at three different times: after induction of anesthesia, during the pneumoperitoneum, and after abdominal deflation, but prior to reversal of anesthesia.

RESULTS

The two groups were similar in age, sex, body mass index, and duration of operation. The CSA slightly increased after the induction of anesthesia, compared with the previous measurements, although there was no statistical significance between them for both groups (P > 0.05). The PFR decreased, whereas the CSA increased during the pneumoperitoneum in each group. The PFR values after basal measurements were significantly higher in the EA/GA than in the GA group (P < 0.05). Group EA/GA had significantly lower heart-rate and blood-pressure levels during surgery than those in group GA (P < 0.05).

CONCLUSIONS

Abdominal insufflation during laparoscopic cholecystectomy results in dilation and decreased flow in the common femoral vein. Epidural analgesia added to the GA partially compensated for the reduction in femoral PFR.

Hemodynamic alterations in the transferred tissue to lower extremities

A higher incidence of failure has been reported for free flaps transplanted to the lower extremities. However, the physiological background of this phenomenon has not been elucidated. We reviewed the 3-day postoperative hemodynamic data for 103 free flaps, including the in situ venous pressure (N = 103), arterial pressure (N = 53), and surface blood flow (N = 42). The cases were divided into two groups based on the recipient site, i.e., lower extremity (the LE group: N = 29) and the other (non-LE group: N = 74). The venous pressure was significantly higher in the LE group (26.6 +/- 2.2 vs. 14.8 +/- 1.2 mmHg), whereas the arterial pressure immediately after surgery was lower than the non-LE group. The hemodynamic data within the transferred tissues demonstrated significant differences between groups, especially in the early postoperative period. There is a possibility that the high venous pressure may aggravate the poor perfusion in tissues transferred to the lower extremities.