*2.3.2 Hourly monitoring*

Despite continuous monitoring of limb perfusion by means of NIRS and DPC flow, hourly inspection for skin colour change, palpation for temperature, capillary return at toe tips, calf palpation and calf girth measurement for compartment syndrome is of paramount importance. Pedal pulses should be checked in the *dorsalis pedis* and

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DPC can introduced at the same time.

**Figure 2.**

*Open cut-down cannulation.*

**2.3 Expectant monitoring of limb**

*2.3.1 Continuous monitoring*

cannula related compromised distal limb perfusion [15].

blood and possible atrial and ventricular thrombus formation. In severe myocardial injury, the heart can be rested with full ECLS flow without ejection. In this case, the need for ventricular decompression should be discussed. With biological no-flow, a case of high vasopressor requirement or expected longer duration of support, the

Peri or post-PCI, with fluoroscopy readily available, all ECLS cannulas can be introduced percutaneously and their position be confirmed before the patient leaves the cath-lab. ECLS as a bridge to transplant in awake patients is a recent trend that offers early ambulation and avoids ventilator-associated complications [29]. However, bedside ECLS can be challenging as a cut down is not comfortable in such patients and difficult outside the environment of the operating theatre. In these patients, the systemic arterial and venous cannulae are introduced percutaneously under local anaesthesia or the patient undergoes a short analgo-sedation as full sedation may be too high risk. As a general principal, contralateral femoral arterial and venous cannulation should be encouraged, as the venous stasis and possible limb oedema caused by the venous cannula may intensify any ipsilateral arterial

Continuous diligent monitoring of the limb for any signs of ischemia is a key to allow for timely and appropriate intervention. One elegant and inexpensive method of continuous monitoring is placing an additional pulse-oximetry probe on the toes of the cannulated limb. Its reading and waveform can be compared with the probe placed on the normal limb. However, hypothermia and non-pulsatile flow may not offer reliable pulse-oximetry reading. Near infra-red spectroscopy (NIRS), routinely used and established in transcranial cerebral oximetry can be helpful in such cases and is an alternative method for continuous monitoring. It involves application of sensor pads on the legs that detects regional oxygen saturation (rSO2)

**Figure 4.** *Continuous DPC flow monitoring.*

posterior tibial artery and when not palpable a hand-held ultrasound Doppler should be utilised to confirm the flow. The flow may be graded for documentation as palpablestrong pulsatile, palpable- weak pulsatile, doppler- pulsatile, doppler- continuous flow and absent flow. Hourly recording of continuously monitored variables namely DPC flow, NIRS rSO2 are necessary to establish trends and detect limb ischemia before it is clinically apparent. Numbers and signs that may be missed during continuous monitoring can be caught in a vigilant hourly survey. Ischemia in toes is seen not uncommon, even in the presence of well-maintained DPC flow due to peripheral micro thromboembolization and/or vasospasm due to peripheral shut down or high dose vasopressors.

## **2.4 Early detection of limb ischemia**

Early detection of inadequate limb perfusion allows for immediate intervention to avoid its catastrophic consequences. In absence of the DPC, continuous NIRS monitoring supplemented by an hourly survey by means of clinical examination and Doppler ultrasound flow check in the distal arteries is usually adequate to detect limb ischemia at an early stage. NIRS rSO2, clinical signs and ultrasound Doppler flow in the cannulated limb should be compared with opposite limb, not to confuse ischemia with peripheral shut down and peripheral vasospasm. In patients with a prophylactic or therapeutic introduction of DPC, it is important to remember that the DPC does not guarantee adequate perfusion. Thus, continuous measurement of DPC flow, maintenance of adequate anticoagulation and monitoring of actual limb perfusion remains essential. Awake non-intubated, non-sedated patients supported on ECLS may complain of pain, tingling- numbness or stiffness with the onset of limb ischemia. An increase in lactate levels without an attributable source and acute kidney failure may be signs of subclinical rhabdomyolysis and should immediately

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**Table 2.**

*Isn't Limb as Precious as Life?*

**2.5 Explantation**

*DOI: http://dx.doi.org/10.5772/intechopen.86391*

**3. Treatment of limb ischemia**

**Management of established limb ischemia** Introduce distal perfusion cannula (DPC)- cut down Percutaneous DPC- Check position with fluoroscopy

Continuous Epoprostenol in DPC

Decompression compartment fasciotomy

Thrombo-embolectomy Change of cannulation site

*Management of limb ischemia.*

Amputation

**3.1 Therapeutic insertion of distal perfusion cannula**

raise suspicion of ischemia. Finally, signs of ischemia may be seen only in the toes,

ECLS is a lifesaver for patients with compromised cardiopulmonary function;

Traditionally, 6 hours are recommended as a golden period for intervention in limb ischemia. In a series analysing limb ischemia in ECLS patients an additional retrograde reperfusion within 6 hours of onset of symptoms avoided amputations completely, whereas the same procedure after that period was burdened with a 20% amputation rate or permanent neurological deficit [34]. Therefore, every attempt should be made to re-establish adequate blood supply in the ischemic limb as soon as possible to avoid catastrophic consequences and residual damage (**Table 2**).

Limb ischemia due to inadequate flow in the distal artery detected at early stage ideally should be treated with the introduction of the DPC if not placed at ECLS implantation. Apart from conscious avoidance, reasons for not introducing

however, it may instigate life-threatening complications and the incidence of complications increases with increase in duration of the ECLS. Yoe *et al.* found the duration of ECLS more than 7 days is a factor associated with the development of limb ischemia [23]. Therefore, weaning of ECLS should begin with recovery of vital organ function with the aim of its explantation as soon as possible. Extra caution is mandated during weaning of patients with the DPC, as the decrease in total ECLS flow decreases DPC flow that may lead to inadequate limb perfusion as well as thrombosis of the DPC. In this situation, the DPC flow should be maintained around at least 300 ml/min by applying a gate clamp on the retrograde arterial cannula. Explantation of ECLS at the end of successful weaning should be performed as an elective case in the operation theatre. The vessels are exposed and controlled with slings before removal of cannulas. Embolectomy is attempted multiple times with balloon tip catheters till satisfactory retro and antegrade blood flow is achieved. The artery is then repaired with or without a patch or an interposition graft to maintain its original calibre without flow limitation. The limb is monitored for at least 48 hours following ECLS explantation for any signs of residual or fresh ischemia.

even with a good DPC flow due to peripheral embolization through DPC.

raise suspicion of ischemia. Finally, signs of ischemia may be seen only in the toes, even with a good DPC flow due to peripheral embolization through DPC.
