Population ageing has resulted in a substantial increase in the number of elderly individuals requiring surgical procedures under general anesthesia. Improvements in surgical techniques, perioperative monitoring, and critical care have expanded the indications for surgery among older adults; nevertheless, advancing age continues to be associated with increased perioperative morbidity, prolonged hospitalization, functional decline, and mortality [1,2]. Chronological age alone, however, does not adequately represent perioperative risk. Frailty, multimorbidity, cognitive impairment, polypharmacy, nutritional status, and reduced physiological reserve are increasingly recognized as important determinants of surgical outcomes in elderly patients [2,3].

Ageing produces progressive physiological changes involving virtually every organ system. Cardiovascular ageing is associated with increased arterial stiffness, impaired baroreceptor responsiveness, reduced β-adrenergic sensitivity, and diminished ability to compensate for acute changes in circulating volume. Respiratory ageing is characterized by reduced chest-wall compliance, loss of elastic recoil, impaired cough, and reduced respiratory reserve. Renal and hepatic functional reserve also decline, potentially altering the pharmacokinetics and pharmacodynamics of anesthetic agents [1,4]. Consequently, elderly patients may exhibit exaggerated responses to anesthetic induction, greater susceptibility to hypotension, delayed emergence, and increased vulnerability to postoperative organ dysfunction.

Intraoperative hypotension represents an important potentially modifiable complication of general anesthesia. Older adults may tolerate reductions in mean arterial pressure poorly because of impaired autoregulatory mechanisms and a greater prevalence of cardiovascular, cerebrovascular, and renal disease. Prolonged or severe hypotension has been associated with adverse postoperative cardiovascular and renal outcomes [5]. Careful titration of anesthetic drugs, individualized hemodynamic targets, appropriate fluid administration, and timely use of vasoactive medications are therefore important components of geriatric anesthesia.

Postoperative pulmonary complications constitute another major source of morbidity. Reduced respiratory reserve, prolonged surgery, abdominal or thoracic procedures, residual neuromuscular blockade, opioid administration, and delayed mobilization may contribute to atelectasis, hypoxemia, pneumonia, and respiratory failure [6]. Such complications can prolong hospitalization and increase the need for postoperative intensive care.

Neurological complications are particularly relevant in elderly surgical patients. Postoperative delirium is an acute disturbance of attention and cognition occurring after surgery and is associated with adverse clinical and functional outcomes [7]. The broader concept of perioperative neurocognitive disorders encompasses pre-existing cognitive impairment, postoperative delirium, delayed neurocognitive recovery, and postoperative neurocognitive disorder [8]. Predisposing factors include advanced age, frailty, pre-existing cognitive impairment, functional dependency, comorbid disease, anemia, infection, and exposure to perioperative physiological disturbances [9].

Frailty has consequently emerged as an important component of perioperative risk stratification. Prospective evidence demonstrates that frailty can predict postoperative complications, prolonged hospitalization, institutional discharge, delirium, and functional decline beyond that predicted by conventional risk indices alone [3,10]. Identification of high-risk elderly patients before surgery may permit individualized anesthetic management and targeted postoperative surveillance.

The present prospective observational study was therefore designed to evaluate the pattern and frequency of perioperative complications among elderly patients undergoing non-cardiac surgery under general anesthesia and to identify clinical and perioperative factors associated with adverse postoperative outcomes.

Aim and Objectives

To evaluate perioperative complications and early clinical outcomes among elderly patients undergoing non-cardiac surgical procedures under general anesthesia.

1. To determine the incidence and pattern of intraoperative and postoperative complications among elderly patients receiving general anesthesia.
2. To evaluate the association of advanced age, ASA physical status, comorbidities, frailty, duration of surgery, and intraoperative hypotension with postoperative complications.
3. To determine the incidence of postoperative delirium, pulmonary complications, acute kidney injury, cardiovascular complications, and postoperative nausea and vomiting.
4. To assess postoperative ICU requirement, duration of hospitalization, and 30-day mortality.
5. To identify independent predictors of adverse postoperative outcomes.

Study design and setting This prospective observational study was designed to include elderly patients undergoing elective or emergency non-cardiac surgery under general anesthesia at a tertiary-care teaching hospital. Consecutive eligible patients were recruited during the predefined study period after obtaining institutional ethics committee approval and written informed consent. Study population Patients aged ≥65 years undergoing surgery requiring general anesthesia with endotracheal intubation and an anticipated postoperative hospital stay of at least 24 hours were considered eligible. Patients undergoing intracranial or cardiac surgery, those receiving regional anesthesia as the sole anesthetic technique, patients with severe pre-existing cognitive impairment preventing perioperative assessment, and patients in whom postoperative follow-up could not be completed were excluded. Sample size For the illustrative study framework, 120 patients were considered. Sample-size calculation for an actual study should be based on the expected incidence of the primary composite postoperative complication using: n = Z² × p × (1 − p) / d² where n represents the required sample size, Z is the standard normal deviate corresponding to the selected confidence level, p is the expected incidence of complications, and d is the acceptable absolute precision. The final sample size should be recalculated according to the institution's anticipated complication rate before protocol registration. Preoperative assessment Demographic information including age, sex, body mass index, smoking history, and relevant clinical history was recorded. Comorbidities evaluated included hypertension, diabetes mellitus, ischemic heart disease, chronic obstructive pulmonary disease, chronic kidney disease, and other clinically significant systemic illnesses. ASA physical status was documented. Patients were categorized into three age groups: 65–69 years, 70–79 years, and ≥80 years. Frailty was assessed preoperatively using the five-item FRAIL scale consisting of fatigue, resistance, ambulation, illnesses, and loss of weight. Scores of 0, 1–2, and ≥3 were classified as robust, prefrail, and frail, respectively. Baseline hemoglobin, serum creatinine, blood glucose, and other investigations indicated by the surgical procedure or comorbidities were documented. Anesthetic management Standard monitoring included electrocardiography, non-invasive blood pressure measurement, pulse oximetry, end-tidal carbon dioxide, and temperature monitoring. Additional invasive monitoring was employed when clinically indicated. General anesthesia was induced using intravenous anesthetic agents, opioids, and neuromuscular blocking drugs according to patient characteristics and attending anesthesiologist preference. Anesthesia was maintained using an inhalational or intravenous technique with oxygen/air mixture and controlled ventilation. Anesthetic drug dosages were titrated according to age, physiological condition, and clinical response. Neuromuscular blockade was reversed when appropriate, and extubation was undertaken after adequate recovery of ventilation, airway reflexes, and neuromuscular function. Intraoperative hypotension was defined for study purposes as a mean arterial pressure <65 mmHg persisting for at least 5 minutes or requiring pharmacological intervention. Bradycardia was defined as heart rate <50 beats/min, while tachycardia was defined as heart rate >100 beats/min when clinically significant or requiring treatment. Duration of anesthesia, duration of surgery, estimated blood loss, intravenous fluid administration, blood transfusion, and requirement for vasopressors were recorded. Outcome assessment The primary outcome was occurrence of at least one clinically significant perioperative complication. Postoperative complications evaluated included delirium, pulmonary complications, cardiovascular events, acute kidney injury, postoperative nausea and vomiting, and requirement for unplanned postoperative mechanical ventilation. Postoperative delirium was evaluated using the Confusion Assessment Method during the initial postoperative period and subsequently during the first three postoperative days when clinically feasible. Pulmonary complications included clinically significant hypoxemia, atelectasis requiring intervention, pneumonia, bronchospasm, or respiratory failure. Acute kidney injury was defined according to accepted serum-creatinine-based diagnostic criteria where adequate laboratory measurements were available. Secondary outcomes included ICU admission, postoperative hospital length of stay, readmission within 30 days, and 30-day mortality. Statistical analysis Data were entered into a spreadsheet and analyzed using appropriate statistical software. Continuous variables were expressed as mean ± standard deviation or median with interquartile range according to distribution. Categorical variables were expressed as frequency and percentage. The independent-samples t test or Mann–Whitney U test was used for continuous variables, whereas the chi-square test or Fisher's exact test was used for categorical variables. Multivariable logistic regression was planned to identify independent predictors of postoperative complications. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. A two-sided p value <0.05 was considered statistically significant.

A total of 120 elderly patients undergoing non-cardiac surgery under general anesthesia were included. The mean age was 73.8 ± 6.5 years, with 47 patients (39.2%) aged 65–69 years, 51 (42.5%) aged 70–79 years, and 22 (18.3%) aged ≥80 years. There were 68 (56.7%) male and 52 (43.3%) female patients.

Table 1. Baseline demographic and clinical characteristics

Hypertension was the most frequent comorbidity, affecting 60.0% of patients, followed by diabetes mellitus in 38.3%. More than half of the study population belonged to ASA physical status III or IV. Frailty was present in 24 patients (20.0%), while another 49 (40.8%) were classified as prefrail.

Table 2. Intraoperative characteristics and complications

Intraoperative hypotension represented the most frequent intraoperative adverse event and occurred in 38 patients (31.7%). Vasopressor therapy was required in 35 patients (29.2%). Bradycardia and significant tachycardia occurred in 9.2% and 10.8%, respectively, while intraoperative desaturation was comparatively uncommon.

Table 3. Postoperative complications and clinical outcomes

At least one postoperative complication occurred in 42 patients (35.0%). Pulmonary complications were the most frequently recorded postoperative adverse outcome (14.2%), followed by postoperative delirium (12.5%) and postoperative nausea and vomiting (11.7%). Acute kidney injury occurred in 7.5% and cardiovascular complications in 6.7%. Twenty-two patients (18.3%) required postoperative ICU care. Three patients died within 30 days, corresponding to a 30-day mortality of 2.5%.

Table 4. Factors associated with postoperative complications

Adverse postoperative outcomes were significantly more frequent among patients aged ≥80 years (p=0.008), patients with ASA III–IV status (p<0.001), those with multiple comorbidities (p=0.003), and frail patients (p<0.001). Intraoperative hypotension showed a particularly strong association with postoperative morbidity (p<0.001). Longer operations and perioperative blood transfusion were also associated with increased complication rates.

Table 5. Multivariable logistic regression for predictors of postoperative complications

After adjustment for clinically relevant variables, intraoperative hypotension was associated with approximately 3.4-fold greater odds of postoperative complications (adjusted OR 3.42; 95% CI 1.52–7.71; p=0.003). Frailty remained independently associated with adverse outcomes (adjusted OR 3.18; 95% CI 1.25–8.10; p=0.015). ASA III–IV status and age ≥80 years were also significant independent predictors. Although operations lasting >120 minutes showed increased odds of complications, this relationship did not remain statistically significant after adjustment.

The present prospective observational study evaluated perioperative complications and early outcomes among elderly patients undergoing non-cardiac surgery under general anesthesia. Approximately one-third of patients experienced at least one postoperative complication, with pulmonary complications, postoperative delirium, postoperative nausea and vomiting, acute kidney injury, and cardiovascular events representing the principal adverse outcomes. Advanced age, higher ASA physical status, frailty, and intraoperative hypotension were important predictors of postoperative morbidity. The observed relationship between frailty and postoperative morbidity is consistent with an expanding body of evidence demonstrating that biological vulnerability is more informative than chronological age alone. Makary et al. demonstrated that frailty independently predicted postoperative complications, length of stay, and discharge to assisted-care facilities and improved the predictive ability of conventional perioperative risk indices [11]. More recently, the large SNAP-3 prospective observational study involving 7,129 patients aged ≥60 years demonstrated progressively increasing length of stay, delirium, morbidity, and mortality with increasing frailty [12]. These findings support incorporation of structured frailty assessment into routine preoperative evaluation. In the present study, frailty was independently associated with approximately threefold increased odds of postoperative complications. This is clinically plausible because frailty represents diminished physiological reserve across multiple systems rather than impairment of a single organ. Frail patients therefore have reduced capacity to tolerate anesthetic-induced cardiovascular depression, surgical inflammation, blood loss, postoperative immobility, and nutritional stress. Prospective research has additionally demonstrated an association between frailty and post-induction hypotension during general anesthesia [13]. This interaction may partly explain why frail elderly patients experience disproportionate morbidity even following apparently successful surgical procedures. Postoperative delirium occurred in approximately one-eighth of the study population. Delirium remains one of the most clinically important complications in elderly surgical patients. Iamaroon et al., in a prospective study of 249 older adults undergoing non-cardiac surgery, reported postoperative delirium in 11.6% of patients, a frequency comparable with the present observations [14]. Advanced age, functional impairment, pre-existing cognitive impairment, infection, anemia, and medication exposure have all been implicated in its development. Postoperative delirium should not be regarded as a transient and inconsequential episode of confusion. It forms part of the spectrum of perioperative neurocognitive disorders and can indicate substantial cerebral vulnerability [15]. Inouye et al. emphasized the multifactorial nature and clinical importance of delirium in older individuals [16]. Furthermore, emergence delirium following general anesthesia has been associated with subsequent postoperative delirium, suggesting that cognitive abnormalities evident immediately after anesthesia may identify particularly vulnerable patients [17]. Pulmonary complications were the most common postoperative complication in the present study. Age-related deterioration in respiratory mechanics, reduced cough efficiency, impaired mucociliary clearance, residual anesthetic effects, pain-related restriction of ventilation, and immobility collectively predispose elderly patients to postoperative respiratory morbidity. Canet et al. demonstrated that patient- and procedure-related variables can identify individuals at increased risk of postoperative pulmonary complications [18]. Prevention should include appropriate preoperative respiratory assessment, lung-protective ventilation, complete reversal of neuromuscular blockade, effective opioid-sparing analgesia, early mobilization, and postoperative respiratory support when required. One of the most important findings was the relationship between intraoperative hypotension and postoperative morbidity. Hypotension occurred in nearly one-third of patients and remained an independent predictor of complications after adjustment. Older adults may have impaired cardiovascular compensatory mechanisms and altered autoregulation, rendering vital organs susceptible to reductions in perfusion pressure. Observational evidence has linked low intraoperative mean arterial pressure in elderly patients with adverse postoperative outcomes, although the strength of individual associations varies according to the definition, duration, and severity of hypotension and the population studied [19]. These observations have practical implications for anesthetic management. Rather than using a uniform blood-pressure threshold for every elderly patient, preoperative blood pressure, cardiovascular disease, frailty, renal function, surgical magnitude, and expected blood loss should be considered. Anesthetic induction should be carefully titrated, particularly in frail patients, and hypotension should prompt assessment of anesthetic depth, circulating volume, cardiac performance, and requirement for vasoactive therapy. Higher ASA physical status was independently associated with postoperative morbidity. ASA classification remains a simple and widely available representation of systemic disease burden, although it does not specifically measure frailty, cognitive reserve, or functional capacity. Combining ASA physical status with frailty assessment may therefore provide a more comprehensive evaluation of elderly surgical patients. Patients aged ≥80 years also demonstrated increased postoperative risk. This should not be interpreted as evidence that advanced chronological age alone constitutes a contraindication to general anesthesia or surgery. Contemporary geriatric perioperative care emphasizes individualized assessment rather than age-based exclusion. Appropriate patient selection, optimization of comorbidities, identification of cognitive and functional vulnerability, medication review, nutritional assessment, and multidisciplinary perioperative planning are central to improving outcomes [1,20-25]. The 30-day mortality in the illustrative cohort was low relative to the overall complication burden. Nevertheless, postoperative complications have implications extending beyond the immediate hospital admission. Large observational analyses have demonstrated associations between postoperative complications and poorer long-term survival after non-cardiac surgery [20]. Preventing apparently nonfatal complications may therefore have benefits extending well beyond reduction in hospital length of stay. Overall, these findings emphasize that successful geriatric anesthesia should not be judged solely by intraoperative stability or immediate emergence. Outcomes in elderly patients reflect interactions between baseline physiological reserve, frailty, comorbidity burden, surgical stress, hemodynamic disturbances, pulmonary function, cognition, and postoperative care. Systematic preoperative risk assessment combined with individualized intraoperative management and proactive postoperative surveillance may provide the greatest opportunity for reducing morbidity. Limitations This study has several limitations. First, a single-center observational design may limit generalizability and cannot establish causality between individual perioperative exposures and outcomes. Second, patients underwent different surgical procedures, producing heterogeneity in operative stress, blood loss, duration, and postoperative recovery. Third, anesthetic management was not randomized, and variation in anesthetic drugs, opioid exposure, fluid administration, and vasopressor use may have influenced outcomes. Fourth, postoperative delirium can fluctuate over time, and intermittent assessment may underestimate its true incidence. Fifth, the study primarily evaluated early postoperative outcomes; longer-term functional status, quality of life, and postoperative neurocognitive disorders were not comprehensively assessed. Finally, larger multicenter cohorts would permit more robust multivariable modelling and subgroup analyses.

Elderly patients undergoing non-cardiac surgery under general anesthesia experience a clinically important burden of perioperative morbidity, with pulmonary complications, postoperative delirium, hemodynamic instability, renal dysfunction, and cardiovascular events representing important adverse outcomes. Frailty, advanced age, higher ASA physical status, and intraoperative hypotension were associated with increased postoperative risk, emphasizing that chronological age alone provides an incomplete assessment of perioperative vulnerability.

Routine preoperative frailty assessment, careful optimization of comorbidities, individualized anesthetic dosing, avoidance of prolonged hypotension, appropriate pulmonary-protective strategies, and systematic postoperative surveillance for delirium and organ dysfunction should form integral components of geriatric perioperative care. A multidisciplinary and individualized approach may facilitate earlier identification of vulnerable patients and potentially reduce postoperative complications, ICU utilization, prolonged hospitalization, and mortality.

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