Is there a way to predict who should go to the ICU after a procedure? Scores are certainly popular in our field. Virginia Apgar devised the 10-point score system that has been demonstrated to assess the health of a newborn. It can predict neonatal survival and is used to determine the intensity of care needed for a newborn. The Aldrete score is used to determine when a patient should be discharged from the post-anesthesia care unit. In their article “The Surgical Apgar Score Is Strongly Associated with Intensive Care Unit Admission After High-Risk Intraabdominal Surgery” published in this month’s issue of Anesthesia & Analgesia, Dr. Julia B. Sobol, Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, New York, NY and colleagues studied patients 18 years of age or older who underwent a major abdominal operation.
The authors collected various pieces of information related to patient characteristics and then determined how that information would predict ICU admission immediately after surgery and in-hospital mortality. Approximately 8500 patients were analyzed. Variables associated with ICU admission included patient age, ASA physical status, whether or not a procedure was emergent, anesthesia duration, and certain types of surgery, including esophagectomy, pancreatectomy, hepatectomy or other hepatobiliary surgery, cystectomy, and major vascular surgery. The Surgical Apgar Score, which uses estimated blood loss, lowest intraoperative heart rate, and lowest intraoperative mean arterial pressure as a means to risk-stratify patients postoperatively, also correlated highly with the decision to admit a patient to the ICU. The authors developed a multivariate model to predict the postoperative decision to admit a patient after surgery and the variables in the model included the Surgical Apgar Score (SAS), ASA physical status, age, gender, emergency procedure, BMI, type of surgery, and anesthetic duration.
This study was retrospective, it included data from only one institution, and it was not designed to predict whether a patient might need ICU admission after surgery prior to the surgery itself.
AA2day interviewed Dr. Julia B. Sobol, the study’s primary author.
AA2Day: How did you first get interested in why patients might need ICU admission?
Dr. Sobol: I became interested in post-surgical ICU admission during my fellowship in critical care, during which ICU triage decisions were made on a daily basis. Limited resources require stratification of patients into those who would benefit most from ICU admission and those who may derive less benefit.
AA2Day: How did you come up with the idea?
Dr. Sobol: In the surgical ICU there were times when it seemed as if patients did not require intensive care but came to the ICU anyway, and others when patients may have benefited from earlier transfer to the ICU. The questions of who should go to the ICU after surgery and how to decide in advance which patients might benefit from ICU admission seemed both appropriate and important to investigate. In particular, the question of whether intraoperative events (such as blood loss) may be helpful for triage of patients is an area that has not been well investigated.
AA2Day: The study was specific to patients undergoing surgery at Columbia University Medical Center. Might patients from other institutions be different? Specifically, there might be some variability as to who is admitted to an ICU when comparing one institution to another.
Dr. Sobol: There is very likely inter-institutional variability as each center has a culture and protocols that may differ. We tried to study as broad a surgical group as possible by including all patients who had undergone major intraabdominal surgery, but this is only a first step. Data from other institutions is clearly needed.
AA2Day: If certain groups of operations were separately analyzed, might the results have been different?
Dr. Sobol: We did separately analyze groups of operations. We found that when stratified by individual surgical procedure, the relationship between the SAS and ICU admission remained consistent, with lower SAS associated with higher rates of ICU admission. However, there may be specific procedures (esophagectomies, for example) in which intraoperative events and the SAS may be less important for clinician decision-making, as these patients may go to the ICU after surgery regardless of what occurs intraoperatively.
AA2Day: What is the takeaway message for our readers?
Dr. Sobol: The message of this study is that the SAS is strongly associated with clinical decisions to admit patients to the ICU after high-risk intraabdominal surgery. While the SAS cannot be used by itself to predict which patients would be admitted to the ICU, it is one of several factors associated with a higher likelihood of ICU admission. Other variables associated with the decision to admit patients to the ICU postoperatively include higher ASA status, longer operations, emergency procedures, and certain high-risk surgeries such as Whipples, hepatectomies, esophagectomies, and major vascular cases. These results provide an initial step towards understanding whether intraoperative events influence ICU triage decisions.
AA2Day: What are your plans for investigating this topic in the future?
Dr. Sobol: We would like to further investigate whether there is a possible role for a predictive score or a model that could be used to match those patients who would benefit most from ICU admission with intensive care after surgery. A prospective evaluation of potential scoring systems would be extremely important.
AA2Day: In your article you note, “A scoring system that can improve on physician decisions would more accurately match appropriate patients to the ICU postoperatively.” This is an interesting thought, but is there any proof?
Dr. Sobol: There is a scarcity of evidence-based information about guidelines and standards for ICU triage after major surgery. While there is no proof to this statement, data have shown that those patients undergoing high-risk surgery who have delayed admission to the ICU postoperatively have significantly worse outcomes than those patients who are admitted to the ICU immediately after surgery.
AA2Day: Might the score be modified or reanalyzed to demonstrate how someone might predict who would be admitted to the ICU prior to surgery?
Dr. Sobol: The SAS is based on intraoperative factors, so it cannot be used prior to surgery. However, clinicians often include preoperative factors in their ICU admission decision-making as well, such as advanced age, comorbidities, and surgical complexity, all of which have been associated with worse postoperative outcomes. It would be possible to modify the SAS to include some of that information, but the major advantage of using this particular score is how easy it is to calculate.