Postoperative sites of care

Vascular surgery carries a high risk of perioperative morbidity and mortality. Over one-third of patients are 75 years or older, with an average of 1.7 comorbidities, including conditions such as hypertension, diabetes, chronic lung disease, and ischaemic heart disease. This further increases the risk of complications and hospital readmissions. As a result, patients undergoing vascular surgery require close postoperative monitoring.

Postoperative complication risks can be assessed using scoring systems like the American Society of Anesthesiologists (ASA) classification, the Lee Revised Cardiac Index, and the Customized Probability Index (CPI). The CPI is a modification of the Revised Cardiac Index that includes clinical risk factors, medication use, and the type of vascular procedure. Scoring systems are particularly effective in identifying low-risk patients, rather than stratifying medium and higher risk patients.

Identifying the most suitable environment for the early detection and treatment of postoperative complications is crucial. The chosen care setting should have staff experienced with the specific surgical procedures and their associated complications. It is important to ensure an appropriate level of monitoring and nursing care. The key factors to consider when selecting the optimal postoperative care site are detailed in Table 1 .

Making appropriate decisions regarding the need for intensive care after surgery is crucial for delivering high-quality patient care. However, accurately determining which patients are at high risk of complications or death following vascular surgery remains challenging. Significant ongoing research in this field includes cardiopulmonary exercise testing, assessing patient frailty and perioperative testing of cardiac biomarkers such as troponin, brain natriuretic peptide (BNP), and N-terminal pro-BNP. Studies involving other patient groups, like the National Emergency Laparotomy Audit (NELA), may also provide valuable insights. Additionally, the national Perioperative Quality Improvement Program (PQIP), a multicentre prospective study in the UK, is expected to provide further information on patient outcomes, aiding the implementation of evidence-based best practices.

Enhanced recovery after surgery (ERAS) pathways are well established in many specialties. There is emerging evidence from studies looking at fast-track pathways applied to open aortic surgery, that ERAS pathways in vascular surgery may decrease postoperative complications. The ERAS Society and Society for Vascular Surgery have published guidelines for open fabdominal aortic aneurysm (AAA) surgery in this area.

General postoperative considerations

The principal objective in the postoperative management of vascular surgery patients is to:

• •
  

  reduce myocardial oxygen demand by optimizing haemodynamic stability

  
  
• •
  

  ensure haemostasis

  
  
• •
  

  maintain normothermia

  
  
• •
  

  provide adequate analgesia.

Comprehensive knowledge of the patient’s preoperative cardiovascular status is essential, including preoperative blood pressure, cardiac function (including any known arrhythmias), and the presence or severity of valvular heart disease or pulmonary hypertension. This detailed understanding is imperative to guide and individualize postoperative management strategies, ensuring optimal outcomes and mitigating the risk of complications.

Myocardial ischaemia

Myocardial infarction (MI) is the predominant cause of mortality following vascular surgery, with reported incidence rates ranging from 6.3% to 8.5%. ^, This high incidence is likely linked to the frequent occurrence of asymptomatic coronary artery disease in this population. An isolated troponin leak observed postoperatively is also significantly associated with an increased risk of 30-day mortality ( Table 2 ). These data underscore the potential value of routine postoperative troponin monitoring for all vascular surgery patients. Nevertheless, the optimal strategies for managing elevated troponin levels, including appropriate follow-up and interventions, remain to be fully defined.

The pathophysiology of perioperative MI is complex and not entirely understood. One contributing factor is perioperative tachycardia, which can lead to increased myocardial oxygen demand and contribute to perioperative ischemia. It is also hypothesized that in the early postoperative period patients probably develop a flow-mediated hypoperfusion, exacerbated by hypotension and thrombosis, secondary to hypercoagulability and inflammation.

Reducing myocardial oxygen demand is essential for minimizing the risk of postoperative myocardial events. Key elements of this approach include maintaining normothermia, optimizing haemodynamic stability, and ensuring effective pain management.

Patients should continue their usual cardiac medications during the perioperative period; for example, abrupt withdrawal of beta-blockers in patients with long-term therapy has been linked to increased mortality. Conversely, initiating β-blockers immediately before surgery can be detrimental, particularly if the patient is anaemic or experiences hypotension. Additionally, discontinuing statins postoperatively is associated with an increased risk of adverse cardiac events. Antiplatelet therapy should be carefully tailored to individual patient needs, especially in those with coronary artery stents to balance the risks of thrombosis and bleeding.

Renal complications

Factors associated with increased risk of acute kidney injury (AKI) in the postoperative period include:

• •
  

  pre-existing renal failure

  
  
• •
  

  emergency surgery

  
  
• •
  

  peripheral vascular occlusive disease

  
  
• •
  

  suprarenal aortic clamp

  
  
• •
  

  ruptured aneurysm

  
  
• •
  

  radiological contrast

  
  
• •
  

  use of vasopressors

  
  
• •
  

  perioperative use of nephrotoxic medication.

Development of this complication carries with it a 60–80% mortality rate in vascular patients. The above risk factors are often unavoidable, but a major contributor to the development of AKI is hypotension and renal ischaemia and most commonly observed in patients with pre-existing chronic kidney disease.

The perioperative strategy should be goal-directed, ensuring adequate intravascular volume, haemoglobin levels and renal perfusion while minimizing exposure to nephrotoxic agents. Inotropes and vasopressors may be indicated to maintain adequate mean arterial pressure. Pre-existing renal failure requires good communication with the patient’s nephrologist to plan timely renal replacement therapy and maintain appropriate fluid balance and opportunity to let anticoagulant effects subside.

Pulmonary complications

Postoperative respiratory failure is associated with an increased mortality, both in the short (30-day mortality of 36.5%) and long term. Pulmonary complications are a significant cause of morbidity after vascular surgery, and cause significant prolongation of ICU and hospital stay. Ventilatory equivalents of carbon dioxide (VE/VCO ₂ ) as measured during CPET has emerged as an important variable in predicting pulmonary complications in patients undergoing AAA repair. A VE/VCO ₂ value exceeding 42 may indicate a heightened risk of significant postoperative pulmonary morbidity and allow clinicians to appropriately plan support and discuss potential risks with the patient.

Advanced age, smoking and associated chronic lung disease frequently accompany vascular disease. Acute respiratory problems should be identified and treatment started, with a delay in surgery if necessary. The likelihood of pulmonary complications varies significantly depending on the type of surgery performed. Open repair of aortic aneurysms requires a laparotomy and/or thoracotomy and therefore carries a more significant risk than for those undergoing surgery for peripheral occlusive disease, endovascular aortic aneurysm or carotid artery disease.

Endovascular repair of thoracic aneurysm is less invasive compared to open but can be complicated by haemothorax requiring drainage and invasive ventilation in the perioperative period. Patients selected for thoracic endovascular repair may be unfit for open repair and therefore less able to tolerate such complications.

Typical pulmonary complications that may occur following vascular surgery include:

• •
  

  atelectasis

  
  
• •
  

  pneumonia

  
  
• •
  

  prolonged mechanical ventilation with requirement of tracheostomy

  
  
• •
  

  the requirement for reintubation

  
  
• •
  

  respiratory failure

  
  
• •
  

  acute respiratory distress syndrome (ARDS).

In postoperative care, there are few interventions with proven efficacy in reducing pulmonary complications. High-flow nasal cannula oxygen delivery has been shown to decrease the incidence of reintubation and the need for additional respiratory support compared to conventional oxygen therapy. Non-invasive ventilation or continuous positive airway pressure (CPAP) devices also have their role in suitable patient groups, such as those with chronic respiratory disorders or heart failure respectively. Practices such as incentive spirometry, chest percussion physiotherapy, intermittent positive pressure ventilation, and deep-breathing exercises may help mitigate pulmonary complications following open abdominal surgery. Local studies have shown successful reductions in the occurrence of respiratory complications using these bundles, such as ICOUGH.

Patients at greatest risk of ARDS are those who have undergone repair of a ruptured AAA associated with massive transfusion of blood products. All ventilated patients will benefit from protective lung strategies.

Gastrointestinal complications

Gastrointestinal complications are most commonly encountered in patients who have undergone surgery for a ruptured AAA (rates of 15–16%). Potentially lethal complications include bowel ischaemia and abdominal compartment syndrome. Although colon ischaemia occurs in less than 2% of patients undergoing elective AAA repair, it has a high mortality rate of 40–65%.

A high index of suspicion should be maintained in the presence of a persistent acidosis, high fluid requirements and refractory shock. Delayed diagnosis can lead to progression to full transmural ischemia, which has a mortality rate of 80–100%.

Patients who are particularly at risk of abdominal compartment syndrome are those who have received large volume fluid resuscitation and blood products. The syndrome is described as:

• •
  

  global hypoperfusion and oliguria

  
  
• •
  

  low cardiac output hypotension

  
  
• •
  

  high ventilatory pressures (caused by reduced pulmonary compliance).

Intra-vesical pressure can be measured to aid diagnosis; high intra-abdominal pressures, or low abdominal perfusion pressures place patients at high risk of compartment syndrome. In such cases, decompressive laparotomy may be indicated; however, the subsequent management of an open abdomen (laparostomy) poses substantial challenges. These include ongoing volume and protein losses, as well as increased risks of bowel injury, infection, and the development of enteric fistulas.

Thromboembolism

Patients undergoing vascular surgery are at increased risk of developing venous thromboembolism. Potential risk factors include advancing age, limb ischaemia, venous injury and lengthy surgery. This group of patients are often hypercoagulable, increasing their risk of deep vein thrombosis or arterial graft occlusion and should receive antithrombotic measures postoperatively. Regional anesthesia is a viable option for postoperative pain management and can help reduce the risk of thromboembolism.

Haemorrhage

Postoperative haemorrhage following vascular surgery may be torrential and life threatening. Immediate management should consist of direct pressure to the area where possible, and resto-ration of an adequate circulating volume. Key targets are haemoglobin >9 g/dl, platelets >75,000, fibrinogen >2 g/litre. Calcium and magnesium should be corrected as necessary, also aiming for normothermia, normocapnia and avoidance of acidosis. Administration of tranexamic acid is useful if fibrinolysis is identified. In some cases, a period of permissive hypotension may be required.

Thromboembolism remains a concern and early use of thromboelastography or thromboelastometry may prove useful in guiding administration of blood products. Rarely, recombinant factor VIIa is required. Arterial thrombotic complications are a significant risk. The decision to administer should be a joint decision with anaesthetist, haematologist and surgeon.

Neurological complications

Detecting deterioration in neurological status is crucial following certain vascular procedures. Spinal cord ischaemia can occur after both open and endovascular thoracic aneurysm repairs, thoraco-abdominal aortic reconstructions, haemorrhagic stroke following carotid endarterectomy, or epidural haematoma in patients with a thoracic epidural. Early recognition of these complications is essential for prompt intervention and improved outcomes.

Postoperative hypertension occurs in 66% of patients post- carotid endarterectomy. Hypertension is associated with myocardial ischaemia, arrhythmias, haematoma formation, haemorrhagic stroke and cerebral hyper-perfusion syndrome. Onset may be delayed but provision should be available for rapid treatment and CT imaging if required.

Spinal cord ischaemia is a potential risk following both open and endovascular thoracic aneurysm repair. In endovascular repair, specific risk factors include extensive stent coverage, occlusion of the left subclavian or hypogastric arteries, and a history of AAA repair. Postoperatively, it is crucial to have the capability to monitor cerebrospinal fluid (CSF) pressures and volumes and to promptly initiate inotropic or vasopressor support to ensure adequate spinal cord perfusion pressure.

Analgesia

Providing high-quality postoperative analgesia has become recognized as an important goal in modifying the risk of major postoperative complications. Postoperative pain is a key contributor to the surgical stress response, and effective pain control is known to reduce myocardial oxygen demand. Evidence suggests that pain-free patients have lower rates of myocardial ischaemia despite having no differences in vital signs compared to those patients with poor analgesia.

In addition to simple analgesics, options available for post-operative analgesia depend on the type of surgery. Controversy surrounds the choice of postoperative analgesia in open aortic surgery. Epidural analgesia provides superior pain relief compared to use of intravenous opiates, especially during movement, for the first three postoperative days. Additionally, patients receiving epidural analgesia typically experience reduced risks of re-intubation and mechanical ventilation, and have reduced rates of myocardial infarction, acute respiratory failure, gastrointestinal, and renal complications. However, there is currently no evidence suggesting a mortality benefit compared to opioid analgesia. An alternative to thoracic epidural is administration of intrathecal diamorphine in high dose for open abdominal surgery or low dose for peripheral vascular surgery in the lower limb. This approach provides pain relief for the first 18–24 hours, with additional intravenous opioids available if needed. Rectus sheath catheters are another regional option for pain management in open abdominal procedures, combined with a patient controlled analgesia of an opiate. They can provide effective post-laparotomy analgesia, while avoiding some of the side effects associated with epidural and opioid analgesia. However, there is currently no published evidence from randomly controlled trials, comparing their efficacy to epidural or opiate analgesia.

Peripheral vascular surgery and carotid surgery lends itself to the use of regional anaesthesia either as a standalone method or in combination with general anaesthesia or sedation. Nerve blocks can mitigate many of the disadvantages of both general and neuraxial anaesthesia. The technique chosen will depend on the site of surgery.For example, perineural catheter infusions following major lower limb amputation can provide analgesia for up to 7 days, providing equivalent analgesia to epidural with lower incidence of immobility, motor block and urinary retention. However, there is no evidence that performing carotid endarterectomy under local anesthesia provides better outcomes when compared to general anesthesia. Similarly, there is limited evidence that epidural analgesia reduces phantom limb pain in peripheral surgeries.

Patients undergoing vascular surgery may present with contraindications to many of these methods of analgesia, particularly if they are on anticoagulants or antiplatelet agents. While opiates have traditionally been the primary choice for postoperative pain management, there is a growing shift towards a multimodal analgesic approach. This approach involves combining different classes of drugs at lower doses to achieve a synergistic effect, aiming to reduce acute pain and minimize secondary hyperalgesia by decreasing perioperative spinal cord sensitization. Gabapentin, ketamine, magnesium, and dexmedetomidine are potential adjuncts to analgesia in vascular patients, especially when regional techniques are contraindicated.

The optimal analgesic strategy should be determined collaboratively by the surgeon, anesthetist, patient, and, if necessary, the cardiologist.