European Journal of Cardiovascular Medicine

Hemodynamic stability is a central objective of anaesthetic management because arterial pressure and heart rate represent readily measurable surrogates of cardiovascular performance and organ perfusion. During surgery, these variables can change rapidly in response to induction of anaesthesia, positive-pressure ventilation, surgical stimulation, blood loss, fluid administration, patient positioning, and vasoactive medications. Although transient alterations are common, marked or repeated fluctuations can expose patients to periods of inadequate or excessive perfusion. Intraoperative hypotension is especially frequent, but its reported incidence varies greatly according to the threshold and duration used to define an event [1].

A substantial body of perioperative research has linked low intraoperative arterial pressure with clinically important postoperative outcomes. Walsh et al. demonstrated graded associations between lower mean arterial pressure (MAP) and myocardial or renal injury after noncardiac surgery [2]. Subsequent large observational analyses reported relationships between intraoperative hypotension, blood pressure variability, and postoperative mortality [3,4]. Salmasi et al. further showed that both absolute MAP thresholds and reductions from baseline were associated with acute kidney and myocardial injury, emphasizing that the magnitude and duration of pressure abnormalities are relevant [5]. These observations have shifted attention from isolated blood pressure readings toward the overall hemodynamic trajectory experienced by the patient.

Hemodynamic variability provides an additional dimension of intraoperative exposure. The coefficient of variation allows dispersion to be expressed relative to the mean and can therefore characterize instability across patients with different baseline values. Greater MAP variability has been associated with mortality after noncardiac surgery even when absolute pressure levels are considered [3]. Interventional evidence also supports the clinical importance of maintaining individualized pressure targets; tighter control of intraoperative blood pressure reduced postoperative organ dysfunction in high-risk surgical patients in a randomized trial [6]. Periods of perioperative hypotension have likewise been associated with myocardial infarction and death [7], while systematic review and consensus work has reinforced the relationship between sufficiently severe or sustained hypotension and adverse postoperative outcomes [8,9].

Early postoperative recovery is a clinically meaningful endpoint that reflects restoration of consciousness, ventilation, circulation, mobility, comfort, and readiness for discharge from the post-anaesthesia care unit (PACU). The modified Aldrete score remains widely used to standardize assessment of recovery after anaesthesia [10,11]. PACU duration is additionally influenced by anaesthetic exposure, intraoperative fluid administration, pain, nausea, vomiting, and cardiorespiratory symptoms [12-14]. However, the contribution of intraoperative hemodynamic variability to the speed of early recovery has received less attention than its association with major organ injury or mortality.

Therefore, the present study was undertaken to evaluate the association between intraoperative hemodynamic variability and early postoperative recovery among patients undergoing elective surgery. The primary objective was to determine the relationship between MAP variability and time to achieve a modified Aldrete score ≥9. Secondary objectives were to examine heart-rate variability, intraoperative hypotension and vasopressor use in relation to delayed recovery and PACU stay, and to identify independent predictors of prolonged early postoperative recovery.

Study design and setting: This prospective observational study was conducted in the Department of Anaesthesiology at Konaseema Institute of Medical Sciences and Research Foundation, Amalapuram, Andhra Pradesh, India, a tertiary-care teaching hospital providing elective general surgical, orthopaedic, gynaecological, and urological services. Recruitment and follow-up were performed from January 2019 to June 2019.

Study population and sampling: Adult patients scheduled for elective surgery were screened consecutively. Patients aged ≥18 years with American Society of Anesthesiologists (ASA) physical status I or II and planned postoperative recovery in the PACU were eligible. Patients undergoing emergency surgery, those with preoperative hemodynamic instability, clinically significant arrhythmia, preoperative vasoactive-drug requirement, or incomplete intraoperative monitoring data were excluded. Eighty eligible patients with complete perioperative data formed the final analytic sample. Consecutive sampling was used to reduce selective enrolment.

Hemodynamic monitoring and exposure variables: Standard monitoring included non-invasive arterial blood pressure, electrocardiography, and pulse oximetry. Baseline blood pressure and heart rate were recorded before induction or initiation of anaesthesia after a short period of rest. Intraoperative MAP and heart rate were recorded at routine clinical intervals throughout anaesthesia. Because definitions of intraoperative hypotension vary [1], hypotension was operationally defined as MAP <65 mmHg or a reduction >20% from baseline. Vasopressor treatment and bradycardia requiring intervention were documented. Hemodynamic variability was summarized using the coefficient of variation, calculated as standard deviation divided by the corresponding intraoperative mean and expressed as a percentage. MAP-CV and heart-rate coefficient of variation (HR-CV) were calculated for each patient.

Postoperative recovery assessment: After surgery, patients were transferred to the PACU and assessed using the modified Aldrete score, which evaluates activity, respiration, circulation, consciousness, and oxygenation [10]. An Aldrete score ≥9 indicated satisfactory early recovery. Time from PACU admission to the first score ≥9 was recorded. Delayed recovery was predefined as requiring >60 minutes to achieve this threshold. Total PACU stay was documented. Pain during the first postoperative hour was assessed using a numerical rating scale. Rescue analgesic requirement, postoperative nausea and vomiting, and excessive sedation were recorded from routine clinical observations. Recovery assessment followed established post-anaesthesia principles [10,11], and PONV was identified using standard clinical criteria [14].

Ethical considerations: The study followed the Declaration of Helsinki. Necessary Permissions were obtained before starting the study. Written informed consent was obtained from each participant before enrolment.

Statistical analysis: Continuous variables were expressed as mean ± standard deviation and categorical variables as frequency and percentage. Recovery groups were compared using the independent-samples t test for continuous variables and chi-square or Fisher exact test for categorical variables. Pearson correlation assessed associations between hemodynamic variability and recovery times. Multivariable linear regression evaluated independent predictors of time to Aldrete score ≥9, adjusting for age, ASA status, duration of surgery, MAP-CV, and intraoperative hypotension. A two-sided P value <0.05 was considered statistically significant.

Participant flow and baseline characteristics

A total of 86 patients scheduled for elective surgery were assessed for eligibility during the study period. Six patients were excluded: three did not satisfy the predefined eligibility criteria, two declined participation, and one had incomplete intraoperative hemodynamic recordings. Consequently, 80 patients were included in the final analysis. Complete intraoperative hemodynamic and early postoperative recovery data were available for all included participants.

The mean age of the study population was 45.7 ± 13.1 years, and 46 (57.5%) participants were males. The mean body mass index (BMI) was 25.6 ± 3.4 kg/m². Forty-three (53.8%) patients belonged to ASA physical status I and 37 (46.3%) to ASA physical status II. The mean duration of surgery was 112.6 ± 37.8 minutes. General surgical procedures constituted the largest group, followed by orthopaedic, gynaecological, and urological procedures (Table 1).

Table 1. Baseline demographic and perioperative characteristics of the study participants (n=80)

Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; SD, standard deviation.

Intraoperative hemodynamic characteristics

The mean baseline MAP was 94.3 ± 11.7 mmHg, while the mean intraoperative MAP was 82.1 ± 8.9 mmHg. The mean MAP-CV was 12.4 ± 4.6%. Baseline and mean intraoperative heart rates were 78.4 ± 12.1 and 76.1 ± 9.7 beats/min, respectively, and the mean HR-CV was 10.1 ± 3.9%. At least one episode of intraoperative hypotension occurred in 27 (33.8%) patients, 23 (28.8%) required vasopressor administration, and 8 (10.0%) developed bradycardia requiring intervention. The mean volume of intraoperative intravenous fluid administered was 1352 ± 482 mL (Table 2).

Table 2. Intraoperative hemodynamic characteristics (n=80)

Abbreviations: MAP, mean arterial pressure; SD, standard deviation.

Early postoperative recovery

The mean time required to achieve a modified Aldrete score ≥9 was 43.2 ± 16.7 minutes, and the mean PACU stay was 72.4 ± 24.8 minutes. Eighteen patients (22.5%) required more than 60 minutes to achieve an Aldrete score ≥9 and were classified as having delayed early postoperative recovery. The mean pain score during the first postoperative hour was 3.2 ± 1.5. Rescue analgesia was required in 23 (28.8%) patients, postoperative nausea and vomiting occurred in 14 (17.5%), and excessive postoperative sedation was documented in 7 (8.8%) patients (Table 3).

Table 3. Early postoperative recovery outcomes (n=80)

Abbreviations: PACU, post-anaesthesia care unit; SD, standard deviation.

Association between hemodynamic variability and postoperative recovery

Patients with delayed postoperative recovery demonstrated greater intraoperative hemodynamic variability than those who recovered within 60 minutes. Mean MAP-CV was 16.1 ± 4.2% in the delayed-recovery group compared with 11.3 ± 4.1% in the earlier-recovery group (P<0.001). HR-CV was also higher among patients with delayed recovery (12.0 ± 3.8% vs. 9.5 ± 3.7%; P=0.012). Intraoperative hypotension occurred in 11 of 18 (61.1%) patients with delayed recovery compared with 16 of 62 (25.8%) patients who recovered within 60 minutes (P=0.005). Vasopressor requirement was likewise more frequent in the delayed-recovery group (50.0% vs. 22.6%; P=0.024) (Table 4).

Table 4. Comparison of intraoperative variables according to early postoperative recovery

Values are mean ± SD or n (%), as appropriate. PACU, post-anaesthesia care unit; MAP, mean arterial pressure.

Correlation analysis

Increasing MAP variability demonstrated a moderate positive correlation with time to achieve an Aldrete score ≥9 (r=0.46, P<0.001) and with total PACU stay (r=0.43, P<0.001). HR-CV showed weaker but statistically significant correlations with time to Aldrete score ≥9 (r=0.29, P=0.009) and PACU duration (r=0.26, P=0.020). Cumulative duration of intraoperative hypotension also correlated positively with time to achieve an Aldrete score ≥9 (r=0.34, P=0.002).

Multivariable analysis

In multivariable linear regression, after adjustment for age, ASA physical status, duration of surgery, and occurrence of intraoperative hypotension, MAP variability remained independently associated with prolonged early postoperative recovery. Each 1% increase in MAP-CV was associated with a 1.31-minute increase in time to achieve an Aldrete score ≥9 (β=1.31; 95% CI: 0.68-1.94; P<0.001). Intraoperative hypotension was independently associated with an additional 8.4 minutes to achieve an Aldrete score ≥9 (β=8.40; 95% CI: 2.39-14.41; P=0.007). Age and duration of surgery were not independently associated with recovery time after adjustment (Table 5).

Table 5. Multivariable linear regression for factors associated with time to modified Aldrete score ≥9

CI, confidence interval; MAP-CV, mean arterial pressure coefficient of variation.

Overall, greater intraoperative hemodynamic variability, particularly MAP variability and the occurrence of intraoperative hypotension, was associated with slower early postoperative recovery and prolonged PACU stay.

The present study demonstrated that greater intraoperative hemodynamic variability was associated with slower early postoperative recovery after elective surgery. Patients who required more than 60 minutes to achieve a modified Aldrete score ≥9 had higher MAP-CV and HR-CV than those with earlier recovery. Intraoperative hypotension and vasopressor use were more frequent in the delayed-recovery group. The correlations between MAP-CV and both recovery time and PACU duration indicate that the pattern of blood pressure fluctuation, rather than a single isolated measurement, has relevance to immediate postoperative recovery.

These findings are consistent with broader evidence linking unstable or reduced intraoperative arterial pressure with adverse perioperative outcomes. Walsh et al. observed progressively greater risks of myocardial and renal injury with lower MAP exposure [2], whereas Mascha et al. reported an independent association between intraoperative MAP variability and 30-day mortality [3]. Monk et al. similarly identified intraoperative hypotension as an exposure associated with mortality [4]. Salmasi et al. showed that absolute and relative hypotension thresholds were both related to myocardial and kidney injury, supporting the concept that sustained deviation from adequate perfusion is clinically important [5]. Although the current study examined early recovery rather than major organ injury, the association is directionally consistent.

A plausible explanation is that repeated fluctuations in arterial pressure produce intermittent reductions in cerebral and systemic perfusion, while also prompting greater use of vasoactive medication and fluid therapy. These factors can interact with anaesthetic depth, surgical stimulation, and autonomic responses and consequently delay restoration of stable circulation and functional recovery in the PACU. The randomized INPRESS trial showed that individualized blood pressure management reduced postoperative organ dysfunction in high-risk patients [6], suggesting that more consistent pressure control can influence postoperative physiology. Similarly, the POISE-2 substudy found clinically important hypotension to be associated with myocardial infarction and death across perioperative periods [7]. Systematic-review evidence also indicates that the harm associated with hypotension increases with both severity and duration [8], and 2019 perioperative consensus recommendations emphasized avoidance of MAP values below approximately 60-70 mmHg during noncardiac surgery [9].

In this cohort, MAP-CV remained independently associated with recovery time after adjustment for age, ASA status, surgery duration, and hypotension. This is noteworthy because prolonged PACU stay is multifactorial. Earlier investigations identified anaesthetic duration, technique, fluid administration, postoperative symptoms, pain, nausea, and vomiting as determinants of PACU discharge [12,13]. The observed rates of postoperative pain, rescue analgesic use, and PONV in the present study therefore represent relevant competing influences. Nevertheless, the persistence of the MAP-CV association after adjustment suggests that hemodynamic instability contributes information beyond basic demographic and operative variables.

The results support intraoperative surveillance of absolute pressure thresholds and overall variability. Clinicians should interpret hemodynamic trends in relation to baseline physiology, surgical context, anaesthetic requirements, and treatment responses rather than isolated readings. Because this was an observational study, the findings establish association rather than causation. Larger prospective studies with continuous beat-to-beat monitoring and standardized anaesthetic protocols are needed to determine whether targeted reduction of intraoperative variability improves early recovery and shortens PACU utilization.

LIMITATIONS

This study has several limitations. It was conducted at a single centre with a modest sample size, which limits external validity and precision of subgroup estimates. Hemodynamic measurements were obtained at routine clinical intervals rather than by continuous beat-to-beat monitoring. Anaesthetic and surgical heterogeneity could contribute residual confounding. The observational design does not establish causality, and postoperative recovery was evaluated only during the early PACU period.

Greater intraoperative hemodynamic variability was significantly associated with delayed early postoperative recovery among patients undergoing elective surgery. Higher MAP-CV, greater heart-rate variability, intraoperative hypotension, and vasopressor requirement were more frequent in patients who required longer to attain a modified Aldrete score ≥9. MAP variability also correlated with prolonged PACU stay and remained independently associated with recovery time after adjustment for selected perioperative factors. These findings highlight the clinical value of maintaining stable intraoperative hemodynamics and evaluating pressure trends rather than isolated measurements. Prospective multicentre studies using continuous monitoring and standardized anaesthetic protocols are warranted to clarify whether strategies that reduce hemodynamic variability can improve recovery efficiency and postoperative outcomes overall,

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