Perioperative complications in high-risk surgical patients remain the leading causes of death and prolonged hospitalization. Although high-risk patients make up approximately 9–15% of surgical procedures they might be responsible for as high as 80% of deaths [1, 2]. The availability of hospital critical care beds shows a large variation worldwide [3], and it is clear that hospital mortality for patients admitted to critical care following surgery is significantly influenced by critical care bed utilization [4•]. On the other hand, several important factors may significantly influence patients’ outcome, especially in the first 24 h postoperatively. These factors are related to the anesthesia team and include preoperative risk stratification, preparation of high-risk patients for elective surgeries, and intraoperative and postoperative measures. In the present review, we intend to summarize the key issues that may be essential from the anesthesiological point of view to ensure a better outcome for high-risk patients and prepare them for intensive care unit (ICU) transfer.

The most important tasks of the anesthesiologist can be summarized as follows:

  1. 1.

    Preoperative identification and optimization of high-risk patients

  2. 2.

    Intraoperative monitoring and therapeutic measures

  3. 3.

    Prevention, recognition, and treatment of intraoperative causes leading to unplanned ICU admission

  4. 4.

    Organizing transport and handover

Preoperative Identification of the “High-Risk” Patient

Different definitions exist for describing high-risk surgical patients. Age, underlying diseases, the complexity of the surgical procedure, and elective or urgent interventions have to be taken into account. In a most generally accepted term, a high-risk surgical patient is defined as a patient having an individual mortality risk of > 5%, the surgical procedure itself poses a mortality risk of > 5%, or both.

For anesthesia providers, the most simple and most widely used risk stratification scoring system is American Society of Anesthesiologists Physical Status (ASA-PS) scoring. According to the report of Wolters et al., the risk of postoperative mortality exceeds 5% in ASA IV grade; thus, per definition, they should be considered high-risk patients, especially if they undergo emergency procedures [5].

Boyd and associates [6••] described a more specific list of criteria for high-risk surgical patients:

  • Previous severe cardiorespiratory illness—acute myocardial infarction, chronic obstructive pulmonary disease, or stroke

  • Late-stage vascular disease involving the aorta

  • Age > 70 years with limited physiological reserve in one or more vital organs

  • Extensive surgery for carcinoma (e.g., oesophagectomy, gastrectomy cystectomy)

  • Acute abdominal catastrophe with hemodynamic instability (e.g., peritonitis, perforated viscus, pancreatitis)

  • Acute massive blood loss > 8 units

  • Septicemia

  • Positive blood culture or septic focus

  • Respiratory failure: PaO2 < 8.0 kPa on FIO2 > 0.4 or mechanical ventilation > 48 h

  • Acute renal failure: urea > 20 mmol/l or creatinine > 260 mmol/l

Another widely used, surgery-related score, the Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM) includes 12 basic preoperative physiologic factors and 6 operative factors. Operative factors may be calculated before surgery, thus enabling a rough estimation of the perioperative risk, but may also be modified after surgery. As some of the parameters are available in the postoperative setting, this score should be used for preoperative risk stratification with caution.

It has to be noted that not all high-risk patients will be transferred to the ICU after surgery. ICU admissions from the operating theater may be categorized as planned and unplanned admissions. Planned ICU admissions in high-risk patients may occur in 5–30% of the cases depending on the local availability of perioperative critical care beds, hospital organization, and local regulations [1, 3, 4•]. Although the availability of perioperative ICU beds may improve outcomes [4•], data are suggesting that adding more ICU beds just adds lower priority ICU admissions, without changing overall hospital mortality [7]. The key here is the proper selection of patients who will benefit from ICU admissions. According to international priority criteria for admission to the ICU, these patients may be priority 1 (= needing immediate organ-supporting treatment, such as ventilatory support, vasoactive medications, renal support) and priority 2 patients (= needing advance monitoring and immediate intervention when needed). One has to realize that monitoring opportunities and the number of qualified staff members may be low in surgical wards; thus, admitting priority 2 patients may result in late ICU admissions. In a large study [1], admission of standard-risk patients resulted in high mortality when they had to be transferred later to the ICU. Proper patient selection and timing of ICU admission are of critical importance because delayed admission is associated with increased mortality [8]. Thus, besides preoperative risk assessment and defining patients who might be at higher risk, it is the anesthesiologist’s responsibility to make a decision at the end of surgery about ICU admission. High-risk surgical patients have increased risk to get decompensated usually in the first 24–48 h postoperatively and thus the effectiveness of the anesthesiologist’s activity extends well beyond what happens in the operating rooms. Several factors help optimize the patient’s condition and thus either avoid ICU admissions or to contribute to a more stable condition before transport. The list of potential measures to be taken by the anesthesiologist in high-risk surgical patients is summarized in Table 1.

Table 1 Basic measures for optimizing patient before transport

The admittance rate of high-risk patients to ICU after emergency and urgent surgical interventions is higher than that after elective, planned surgeries. In these patients, the opportunities for hemodynamic stabilization and preoperative preparation of the patients are limited and therefore the role of the anesthesiologist’s work to achieve stable vital parameters during surgery is of paramount importance.

The Decision About ICU Admission and Organization of Transport

It is the anesthesiologist’s responsibility to decide the level of required care for the patient after surgery, with the operating surgeons involved. Ideally, the necessity of ICU admission can be unequivocally decided before starting surgery and the critical care team can be informed about the demand on the bed. This advance notification is the anesthesiologist’s responsibility. According to several studies, ICU team members require this notification because then they have the opportunity to prepare necessary equipment and supplies and thus handoff may be more patient-focused [16, 17••, 18]. For unanticipated ICU admissions (due to emergency high-risk surgeries or intraoperative complications), it is also required that the senior anesthesiologist of the team warns the ICU members about the demand on critical care beds as early as possible. Ideally, this includes pre-handoff communication 30–60 min before the end of surgery and an immediate warning before the transport [16]. It has been proven that patient transport by the anesthesiologist team is as safe as transporting patients by ICU specialists. ICU service can improve turnover times and workflow in the operating room (OR) [19].

Organizing Transport

There are different structures of OR and critical care worldwide. In some countries, anesthesiologists and intensive care specialist share a common specialization and thus perioperative and postoperative care occurs in the frame of one department. In other countries, anesthesia and intensive care are split into two specializations. Thus, in some institutions, a dedicated team of the critical care unit is responsible for the transport, while in others it is the anesthesia team’s responsibility. Whatever the case is, it is important to have a local protocol describing the members of teams and their responsibilities during transport from the OR to the ICU.

Most important serious adverse events during transport make up approximately 4.2–8.9% of critically ill cases. The majority of them are cardiovascular (severe alterations in blood pressure, arrhythmias, cardiac arrest), neurological (agitation or elevation of intracranial pressure), respiratory (patient-ventilator asynchrony, hypercapnia, hypoxia, bronchospasm, accidental extubation), and hypothermia [19]. Some of the incidents are related to organizational or human errors, such as equipment malfunction due to battery/electric or oxygen tank failure. To avoid them, every institution should work out a checklist of devices that have to be readily available for the transport of critically ill patients. In some institutions, one of the biggest concerns with transitioning care from the OR to the ICU is when the OR team boluses vasoactive medications just before handoff to prevent suboptimal hemodynamics during handoff. While this can improve the clinical picture, the effects are often transient and the patient becomes hypotensive shortly after handoff has occurred once the medication effect has ceased. Although bolus doses of vasopressors administered before transport may result in a temporary elevation of blood pressure in critically ill hypotensive patients, there are results indicating worse outcomes and increased mortality [20]. To avoid this suboptimal practice, vasoactive drugs should be continuously administered through perfusion during transportation and attention should be paid to the proper volume replacement therapy. The necessary drugs and devices are summarized in Fig. 1. It is the dedicated transport team’s responsibility to control the readiness of all types of equipment for transport (recharging batteries, checking oxygen vials) and the completeness of the drug lists. It has been proven that the use of locally developed checklists and regular training of the staff being involved in the transport procedure may largely improve patient safety [21].

Fig. 1
figure 1

Necessary factors for transport of the critically ill. Abbreviations: ECG, electrocardiogram; NBP, non-invasive blood pressure; IBP, invasive blood pressure; CVP, central venous pressure

Patient Handover

Several studies indicated that approximately half of the critical incidents occurring during transport are human-related [22]. Among them, information transfer during patient handover is one of the most important. It has been shown that poor communication is the second most common cause of critical incidents, corresponding to 14% [23], and patients whose transport team exhibited less detailed information sharing at ICU handover were at higher risk for critical complications [24]. It has to be emphasized that an adequate time span and quiet environment have to be ensured for an appropriate handover to avoid incomplete information transfer [25]. Optimally, a detailed handover has to include basic patient-related information, including age, previous diseases, and indications for surgery followed by information related to anesthesia and the surgical intervention. A very important part of patient handover should be related to the transport itself; all eventual incidents that occur during transportation have to be documented and verbally shared. The status of the patient at the time of handover has to be checked and documented in common by the transport and the ICU team members. The most important information about patient handover is summarized in Table 2. In many countries, the flowchart of handover communication is based on the SBAR (Situation, Background, Assessment, Recommendation) technique [26].

Table 2 Postoperative information transfer recommendations consistently identified in the literature

It has to be underlined that it is not enough to have a detailed description of handover at the institutions, a regular teaching and simulation practice program are necessary for the staff involved in the procedure, and it has to become an integral part of both the gradual and residency teaching programs [27••, 28, 29].


Preparing critically ill patients for ICU transfer starts in the preoperative phase by optimization of the patient’s status. Anesthesiologists are involved in the intraoperative and postoperative phases of stabilization. An important task is to organize transport and handover, which need interdisciplinary communication and cooperation.