Preoperative evaluation: Impact on early perioperative hemodynamic and respiratory complications

Abstract

Background

The impact of routine preoperative anesthesia evaluations on potential perioperative complications remains unclear. This study aimed to investigate the effect of preoperative evaluation on early perioperative hemodynamic and respiratory complications.

Methods

This prospective observational study analyzed data from patients aged 18 to 80 who underwent elective surgery between October 15, 2023, and February 15, 2024. The study evaluated the effect of preoperative anesthesia evaluation on hemodynamic and respiratory complications occurring during surgery and within the first 24 h postoperatively, as well as its impact on the length of hospital stay.

Results

The analysis included 1117 patients for whom complete data was available. Hemodynamic and respiratory complications were observed in 545 patients (48.7%), occurring within the first 24 h intraoperatively and postoperatively. Because no additional examinations beyond routine blood tests, radiological imaging, and electrocardiograms were performed in the preoperative period, the impact of these tests on the development of hemodynamic and respiratory complications could not be determined. There was no statistically significant association between the presence or absence of preoperative consultation and the occurrence of early perioperative hemodynamic and respiratory complications [OR (95% CI): 0.879 (0.646–1.195); P = 0.411], nor did it affect the length of hospital stay [median (IQR); 2 (3) vs. 2 (3); P = 0.245].

Conclusion

While the impact of routinely requested laboratory and imaging methods before surgery could not be assessed in this study, consultations that were requested did not affect hemodynamic and respiratory complications in the early perioperative period or on the duration of hospital stay.

Trial registration number

Samsun University Samsun Training and Research Hospital, following ethics committee approval (Samsun University clinical research ethics committee (KAEK) 2.12.2023) and Clinical Trials (NCT06203171 / 04.18.2024) registration.

Introduction

Annually, more than 300 million surgical procedures are performed worldwide; however, both the volume and types of surgeries differ considerably across various regions [1, 2]. During the perioperative period, major complications arise in 3–16% of patients, and 0.4–0.8% of these patients experience permanent disability or death. In low- and middle-income countries, the prevalence of permanent disability or mortality resulting from perioperative complications may reach levels between 5% and 10% [3]. Preoperative assessments for surgical patients aim to identify potential risks during the perioperative period, improve the patient’s functional and physiological condition, and reduce the likelihood of complications [4].

The literature has no standard definition for pre-anesthetic evaluation [5]. The preoperative assessment involves collecting information from multiple sources, including the patient’s medical history, interviews, physical examinations, medical tests, and evaluations. Throughout this process, the anesthesiologist may collaborate with other healthcare professionals to obtain relevant information or services related to perioperative anesthesia care [6, 7]. Medical specialists perform preoperative assessments for 10–40% of patients undergoing elective surgery. However, the number of studies showing the effects of preoperative anesthesia evaluation on patient safety is limited in the literature [8, 9]. In vascular surgery, 1 randomized clinical trial demonstrated that preoperative geriatric care reduced the length of stay. In surgical oncology, 2 randomized clinical trials found no difference in complications, length of stay, or readmissions [10]. Additionally, rising healthcare costs are a major concern for the entire system, including insurance companies and the pharmaceutical industry [11]. Research estimates suggest that approximately 30% of total healthcare expenditures are associated with medical interventions that offer minimal or no clinical benefit [12].

In this study, we conducted an extensive investigation into the impact of preoperative anesthesia assessments on the occurrence of perioperative early hemodynamic and respiratory complications. Our research aimed to evaluate whether these assessments effectively mitigate the risks associated with surgical procedures by examining their influence on patient outcomes during the perioperative period.

Materials and methods

This prospective observational study was conducted adhering to the principles stated in the Declaration of Helsinki. Approval was received from the local ethics committee under the reference number SUKAEK 2023-12/2. The study was registered in the Protocol Registration and Results System (ClinicalTrail.gov NCT06203171). Due to the observational nature of the study and institutional review rules, patient consent was not obtained.

Population

We aimed to include patients who underwent surgery between October 15, 2023, and February 15, 2024. All patients were preoperatively evaluated by an anesthesiologist. The study population consisted of individuals aged 18 years or older who underwent various non-cardiothoracic and non-aortic surgeries, including elective procedures. Eligible patients had an American Society of Anesthesiologists (ASA) physical status classification of 3 or lower, as determined during the preoperative assessment and confirmed by the investigator. Patients under 18 years of age, pregnant patients, patients undergoing emergency surgery, and patients with ASA ≥ 4 were excluded.

Protocol

In the early perioperative period, three anesthesia residents conducted a thorough evaluation of complications identified according to the study protocol. They assessed each patient’s clinical condition through comprehensive examination and closely reviewed nursing observations recorded during this period. Based on these evaluations, patients were divided into two distinct groups: those with perioperative complications (Group C) and those without complications (Group non-C). The following patient information was documented prior to surgery: age, gender, height, weight, and pre-existing comorbidities (refer to the pre-agreed standard definitions and additional methodological details in Appendix 1).

The preoperative data recorded included routine laboratory parameters, complete blood count (CBC), electrolytes (Na, K, Cl), blood urea nitrogen (BUN), creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), bleeding profile (PT, aPTT, INR), chest X-ray results, electrocardiography (ECG) results (if available within 30 days before surgery), fingertip oxygen saturation percentage, hemodynamic values (systolic blood pressure, diastolic blood pressure, mean blood pressure, heart rate), ASA classification, and whether the surgery was classified as emergency or elective.

During the intraoperative period, data collection included details of the surgical procedure, surgery duration (from incision to completion), anesthesia duration (from induction to extubation), mechanical ventilation settings, vital signs, use of regional anesthesia, intraoperative medications and fluids, and the occurrence of hemodynamic and respiratory complications intraoperatively and within the first 24 h postoperatively. Furthermore, the duration of stay in the post-anesthesia care unit (PACU), total hospital stay, and discharge type were documented.

Outcomes

The primary endpoint of this study was to assess the impact of preoperative anesthesia evaluation, requested consultations, and laboratory and imaging investigations on (I) intraoperative and early postoperative hemodynamic and respiratory complications within the first 24 h (Appendix 1; e-Appendix in the Supplement) and (II) discharge time.

Statistics

The postoperative hemodynamic and respiratory complication rate was calculated as 95% confidence (1-α), 95% test power (1-β), Proportion p1 = 0.558, and Proportion p2 = 0.452 with a minimum of 493 cases for both groups [13]. To mitigate potential data loss, we increased the sample size by 10%. The data analysis was conducted using the Statistical Package for the Social Sciences (SPSS) software, provided by IBM Corporation, based in Armonk, NY, USA. To ensure accurate and comprehensive data interpretation, the presentation of the data was determined based on the results of normality testing. Quantitative data were expressed in two ways: as the mean value along with the standard deviation (mean ± SD) for normally distributed data, and as the median accompanied by the interquartile range (IQR) for data that did not follow a normal distribution. Categorical data were presented in terms of frequency and percentage. To compare quantitative variables between different groups, the Mann-Whitney U test was employed, given its robustness for handling non-normally distributed data. For the comparison of categorical variables, the Chi-square (χ2) test or Fisher’s exact test was utilized, depending on the expected frequency counts and the suitability of these tests for the data distribution. In addition to these tests, variables that potentially influenced the development of hemodynamic and respiratory complications were thoroughly evaluated using both binary logistic regression and multiple logistic regression analyses. These regression analyses were essential in identifying significant predictors and assessing their individual and combined effects on the outcomes. All statistical tests conducted were two-sided, and a p-value of less than 0.05 was considered the threshold for statistical significance. This criterion ensured that the findings were robust and provided a high level of confidence in the results derived from the analyses.

Results

During the study period, 4781 patients underwent surgery. The number of patients whose study data were accessed was 1147. Thirty of these patients were excluded according to the study protocol. The study was completed with 1117 patients (Fig. 1).

Fig. 1

Flow diagram

Table 1 demonstrates the patients’ demographic and clinical characteristics. Hemodynamic and respiratory complications defined as primary outcomes were detected in 545 patients (48.7%), During intraoperative monitoring, hemodynamic complications were observed in 595 cases (51.3%), while respiratory complications occurred in 16 cases (1.4%). In the early postoperative period, there were 379 cases (23%) of hemodynamic complications and 119 cases (10.7%) of respiratory complications. Additionally, 47 patients (4.2%) required admission to the intensive care unit postoperatively (Table 2).

Table 1 Patient demographic and clinical characteristics

Table 2 Incidence of Perioperative complications

No additional investigations other than routine blood tests, radiologic imaging, and ECG were requested by the Department of Anesthesiology and Reanimation in all patients in the preoperative period. Preoperative consultations were requested for a total of 374 patients.

Patient age [OR (95% CI): 1.017 (1.005–1.029); P = 0.005], coronary artery disease [OR (95% CI): 0.213 (0.118–0.386); P < 0.001] and ASA score [OR (95% CI): 6.816 (4.742–9.797); P < 0.001] were associated with consultation request. Among patients who required consultation, the mean interval from the preoperative anesthesia evaluation to surgery was 16.5 days, compared to 13.7 days in those who did not require consultation [median (IQR): 14 (16) vs. 9 (15); P < 0.01].

None of the patients experienced acute coronary syndrome, severe postoperative atelectasis, reintubation, or unplanned postoperative mechanical ventilation during the early perioperative period. All variables, study group characteristics, and bivariate and multivariate analysis results are in Appendix 1 (e-Appendix in the Supplement). Table 3 includes the factors affecting perioperative complications.

Table 3 Effect of variables on perioperative complications

Since no additional examinations beyond routine blood tests, radiologic imaging, and ECG were conducted for any patients during the preoperative period, we were unable to assess the impact of these results on hemodynamic and respiratory complications. There was no statistically significant association between the presence or absence of preoperative consultation and the occurrence of early perioperative hemodynamic and respiratory complications [OR (95% CI): 0.879 (0.646–1.195); P = 0.411]. Chronic Obstructive Pulmonary Disease [OR (95% CI): 3.145 (1.545–6.399); P = 0.002], a history of asthma [OR (95% CI): 0.466 (0.252–0.863); P = 0.015], and ASA score [OR (95% CI): 1.373 (1. 041–1.813); P = 0.025] were associated with perioperative hemodynamic and respiratory complications. Patients with perioperative complications had higher hospital lengths of stay [Group C vs. Group non-C median (IQR); 2 (3) vs. 2 (2); P = 0.01] (Fig. 2).

Fig. 2

Patients hospital lengths of stay

Consultations requested after preoperative evaluation did not affect the length of hospital stay [median (IQR); 2 (3) vs. 2 (3); P = 0.245].

Discussion

In this prospective observational study, we observed that approximately half of the patients had hemodynamic and respiratory complications in the perioperative period. No relationship was detected between preoperative evaluations and consultations and the occurrence of hemodynamic and respiratory complications. High ASA score, history of COPD and asthma were associated with perioperative hemodynamic and respiratory complications. Perioperative complications significantly prolonged hospital stay. The lack of effect of preoperative evaluation and requested consultations on the outcomes is consistent with observational data from previous periods [10]. We found that patients with age, coronary artery disease, and high ASA scores were more likely to be consulted for perioperative complications. The absence of a clear association between complications and preoperative evaluations suggests the need for improvements in identifying target populations, refining evaluation processes, and optimizing interventions.

Complications that may occur after surgery, especially hemodynamic and respiratory complications, are important causes of morbidity and negatively affect the length of hospital stay [14]. Therefore, many large-scale studies have dealt with hemodynamic and respiratory optimization in the perioperative period [15,16,17]. However, the literature offers limited information on perioperative practices that reduce the predicted potential complications [18, 19]. One study specifically investigated the effects of prolonged-release metoprolol succinate in patients undergoing non-cardiac surgery to prevent perioperative hemodynamic complications. This study unexpectedly found an increased risk of stroke and mortality rather than the anticipated improvement in outcomes [20]. Most studies examining preoperative medical evaluations and outcomes usually focus on cardiac risk. It should be kept in mind that any perioperative complications that may develop may be related to both the patient’s comorbidities and other systemic complications. Despite this, there is limited evidence to guide the management of other prevalent medical conditions, such as perioperative respiratory diseases and diabetes mellitus [21, 22]. In our study, early perioperative hemodynamic and respiratory complications were analyzed, revealing an association between a history of COPD, asthma, and ASA score with perioperative complications. However, preoperative evaluations were found to have no impact on these complications. Partridge et al. showed that detailed evaluation of geriatric patients before vascular surgery shortens the length of hospital stay [23]. Another study found that preoperative evaluations reduced the mortality rate in patients classified as ASA 3 or higher [24]. Both studies focused on high-risk patients and demonstrated positive effects of comprehensive preoperative evaluations on the measured outcomes. In contrast, our study involved elective and non-high-risk patients, which may explain the differences between our findings and those of both studies.

Another important reason for preoperative consultations is the potential medicolegal problems. The extent to which preoperative consultations address medicolegal issues remains unclear. Inadequate evaluation of the patient by the consultant can result in significant liability; consequently, consultants often refrain from providing specific instructions [25]. At the same time, intraoperative management, including choice and technique of anesthesia and types of monitoring, is within the core expertise of anesthesiologists. Cardiovascular complications, which are associated with considerable medicolegal concerns during the perioperative period, likely contributed to the higher rate of preoperative cardiology consultations requested for patients with coronary artery disease in our study. However, no statistically significant relationship was found between these cardiology consultations and the occurrence of hemodynamic complications during the perioperative period.

It is essential to optimize interventions aimed at minimizing complications that may arise from the preoperative evaluation process. Unnecessary examinations and assessments not only fail to prevent potential complications but may also lead to surgical delays, which can adversely affect patient outcomes. In our study, we observed that the duration from the initial evaluation to the surgical procedure was significantly prolonged in patients for whom consultations were requested. This finding highlights the need for a more streamlined approach to preoperative evaluations, focusing on relevant assessments that effectively mitigate risks without contributing to delays in surgical intervention. Also in the perioperative period, information exchange between the surgical team, anesthesiologists, and, if necessary, intensive care specialists about specific cases is important in reducing possible perioperative complications, especially in high-risk patients [26]. The intensity of appropriate communication between the surgical team and anesthesiology should be adjusted according to patient characteristics. We believe that the effects of appropriate communication and collaboration on patient outcomes should also be investigated in order to reduce perioperative complications.

Although preoperative medical consultation is commonly used by clinicians, the evidence supporting its effectiveness remains inconsistent [10]. In our study, no statistically significant relationship was found between preoperative consultations and the occurrence of hemodynamic or respiratory complications during the perioperative period. However, given the increased morbidity, mortality, and medicolegal risks associated with perioperative complications, we believe that future research may help clarify the appropriate role and impact of preoperative consultations.

Preoperative anesthesia assessments are widely recognized as a crucial step to enhance patient safety by identifying and mitigating potential risks prior to surgery. However, the anticipated improvements in patient safety outcomes associated with these assessments have not been achieved consistently across the globe. Notably, low- and middle-income countries continue to experience significantly higher rates of intraoperative and perioperative mortality and complications compared to their high-income counterparts. These disparities in patient safety outcomes are largely driven by a range of complex factors, including the varying availability and utilization of healthcare resources, differences in healthcare infrastructure and support systems, and disparities in the training and distribution of skilled healthcare personnel. Additionally, efforts to collect and analyze patient safety outcome data vary widely between regions, which can impact the establishment and enforcement of standards of care. Furthermore, the safety culture and the emphasis on teamwork within healthcare facilities play essential roles in influencing patient outcomes [27]. Given these varied influences, we advocate for our data to be tested, validated, and adapted in other regions and countries. Such adjustments would allow for tailoring to the specific healthcare dynamics, infrastructure, and resource availability unique to each region, thereby optimizing the potential impact on patient safety.

Limitations.

During the preoperative period, the necessity of routine laboratory and imaging tests posed a challenge in comprehensively evaluating their influence on consultation requests and patient outcomes. Additionally, there has been a lack of comprehensive analysis regarding how the evaluation notes and physical examination findings documented by the anesthesiologist during the preoperative anesthesia assessment, particularly in the determination of the ASA physical status classification, may influence the occurrence of perioperative complications, such as hemodynamic instability and respiratory events. The potential role of these preoperative evaluations in predicting or mitigating adverse outcomes during the perioperative period unexamined. The participation of various surgical and anesthesia teams in the preoperative assessment of patients undergoing a diverse range of surgical procedures may have introduced variability in the approach to preoperative investigations, the nature and extent of consultations, and, consequently, the outcomes being analyzed in this study. The differing practices, clinical judgment, and protocols followed by each team could have contributed to inconsistencies in the thoroughness of preoperative evaluations, which in turn may have affected the reliability of the findings related to perioperative complications. Furthermore, our assessment was confined to intraoperative and early postoperative hemodynamic and respiratory complications as outlined in the study protocol. The absence of an evaluation of complications that may manifest beyond the initial 24-hour period represents an additional limitation of our study.

Conclusion

Although consultations were requested based on certain risk factors (e.g., age, ASA score), they did not significantly reduce the incidence of hemodynamic and respiratory complications. However, requested consultations did lead to a longer surgical waiting time. A personalized preoperative assessment and consultation, tailored to the individual’s risks and benefits, could optimize the healthcare system’s limited resources and potentially improve patient outcomes.