Spinal analgesia in cardiac surgery: a meta-analysis of randomized controlled trials

Intrathecal Morphine for Cardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

ABSTRACT

Cardiac surgeries often result in significant postoperative pain, leading to considerable use of opioids for pain management. However, excessive opioid use can lead to undesirable side effects and chronic opioid use. This systematic review and meta-analysis aimed to evaluate whether preoperative intrathecal morphine could reduce postoperative opioid consumption in patients undergoing cardiac surgery requiring sternotomy. We conducted a systematic search of Cochrane, EMBASE, and MEDLINE databases from inception to May 2022 for randomized controlled trials that evaluated the use of intrathecal morphine in patients undergoing cardiac surgery. Studies that evaluated intrathecal administration of other opioids or combinations of medications were excluded. The primary outcome was postoperative morphine consumption at 24 h. Secondary outcomes included time to extubation and hospital length of stay. The final analysis included ten randomized controlled trials, with a total of 402 patients. The results showed that postoperative morphine consumption at 24 h was significantly lower in the intervention group (standardized mean difference -1.43 [-2.12, -0.74], 95% CI, P < 0.0001). There were no significant differences in time to extubation and hospital length of stay. Our meta-analysis concluded that preoperative intrathecal morphine is associated with lower postoperative morphine consumption at 24 h following cardiac surgeries, without prolonging the time to extubation. The use of preoperative intrathecal morphine can be considered part of a multimodal analgesic and opioid-sparing strategy in patients undergoing cardiac surgery.

Analgesic efficacy and risk of low-to-medium dose intrathecal morphine in patients undergoing cardiac surgery: An updated meta-analysis

Background

To evaluate the analgesic efficacy and risk of low-to-medium dose intrathecal morphine (ITM) (i.e., ≤0.5 mg) following cardiac surgery.

Methods

Medline, Cochrane Library, Google scholar and EMBASE databases were searched from inception to February 2022. The primary outcome was pain intensity at postoperative 24 h, while the secondary outcomes included intravenous morphine consumption (IMC), extubation time, hospital/intensive care unit (ICU) length of stay (LOS), and ITM-associated side effects (e.g., respiratory depression). Subgroup analysis was performed on ITM dosage (low: <0.3 mg vs. medium: 0.3–0.5 mg).

Results

Fifteen RCTs involving 683 patients published from 1988 to 2021 were included. Pooled results showed significantly lower postoperative 24-h pain scores [mean difference (MD) = −1.61, 95% confidence interval: −1.98 to −1.24, p < 0.00001; trial sequential analysis: sufficient evidence; certainty of evidence: moderate] in the ITM group compared to the controls. Similar positive findings were noted at 12 (MD = −2.1) and 48 h (MD = −1.88). Use of ITM was also associated with lower IMC at 24 and 48 h (MD: −13.69 and −14.57 mg, respectively; all p < 0.05) and early tracheal extubation (i.e., 48.08 min). No difference was noted in hospital/ICU LOS, and nausea/vomiting in both groups, but patients receiving ITM had higher risk of pruritus (relative risk = 2.88, p = 0.008). There was no subgroup difference in IMC except a lower pain score with 0.3–0.5 mg than <0.3 mg at postoperative 24 h. Respiratory depression events were not noted in the ITM group.

Conclusion

Our results validated the analgesic efficacy of low-to-medium dose ITM for patients receiving cardiac surgery without increasing the risk of respiratory depression.

Intrathecal Morphine for Analgesia in Minimally Invasive Cardiac Surgery: A Randomized, Placebo-controlled, Double-blinded Clinical Trial

BACKGROUND

Intrathecal morphine decreases postoperative pain in standard cardiac surgery. Its safety and effectiveness have not been adequately evaluated in minimally invasive cardiac surgery. The authors hypothesized that intrathecal morphine would decrease postoperative morphine consumption after minimally invasive cardiac surgery.

METHODS

In this randomized, placebo-controlled, double-blinded clinical trial, patients undergoing robotic totally endoscopic coronary artery bypass received either intrathecal morphine (5 mcg/kg) or intrathecal saline before surgery. The primary outcome was postoperative morphine equivalent consumption in the first 24 h after surgery; secondary outcomes included pain scores, side effects, and patient satisfaction. Pain was assessed via visual analog scale at 1, 2, 6, 12, 24, and 48 h after intensive care unit arrival. Opioid-related side effects (nausea/vomiting, pruritus, urinary retention, respiratory depression) were assessed daily. Patient satisfaction was evaluated with the Revised American Pain Society Outcome Questionnaire.

RESULTS

Seventy-nine patients were randomized to receive intrathecal morphine (n = 37) or intrathecal placebo (n = 42), with 70 analyzed (morphine 33, placebo 37). Intrathecal morphine patients required significantly less median (25th to 75th percentile) morphine equivalents compared to placebo during first postoperative 24 h (28 [16 to 46] mg vs. 59 [41 to 79] mg; difference, -28 [95% CI, -40 to -18]; P < 0.001) and second postoperative 24 h (0 [0 to 2] mg vs. 5 [0 to 6] mg; difference, -3.3 [95% CI, -5 to 0]; P < 0.001), exhibited significantly lower visual analog scale pain scores at rest and cough at all postoperative timepoints (overall treatment effect, -4.1 [95% CI, -4.9 to -3.3] and -4.7 [95% CI, -5.5 to -3.9], respectively; P < 0.001), and percent time in severe pain (10 [0 to 40] vs. 40 [20 to 70]; P = 0.003) during the postoperative period. Mild nausea was more common in the intrathecal morphine group (36% vs. 8%; P = 0.004).

CONCLUSIONS

When given before induction of anesthesia for totally endoscopic coronary artery bypass, intrathecal morphine decreases use of postoperative opioids and produces significant postoperative analgesia for 48 h.

EDITOR’S PERSPECTIVE

Current Status of Neuraxial and Paravertebral Blocks for Adult Cardiac Surgery

Cardiac surgeries are known to produce moderate to severe pain. Pain management has traditionally been based on intravenous opioids. Poorly controlled pain can result in increased incidence of respiratory complications such as atelectasis and pneumonia leading to prolonged intubation and intensive care unit length of stay and subsequent prolonged hospital stay. Adequate perioperative analgesia improves hemodynamics and immunologic responses, which would result in better outcomes after cardiac surgery. Opioid sparing "Enhanced Recovery After Surgery" protocols are increasingly being incorporated into cardiac surgeries. This will reduce opioid requirements and opioid-related side effects and facilitate fast-tracking of patients. Regional analgesia can be provided by neuraxial blocks, fascial plane blocks, peripheral nerve blocks, or simply by the infiltration of the wound with local anesthetics for cardiac surgery. Neuraxial analgesia is provided through epidural, spinal, and paravertebral routes. Though they are being replaced by peripheral fascial plane blocks, epidural and spinal analgesia are still being used in some centers. In this article, neuraxial forms of analgesia are focused. We sought to review epidural analgesia and its impact in suppressing hemodynamic stress response, reducing pulmonary complications, and development of chronic pain. The relationship between intraoperative heparinization and potential neuraxial hematoma is discussed. Other neuraxial options such as spinal and paravertebral analgesia and their usefulness, benefits, and limitations are also reviewed.

Spinal Anesthesia Increases the Frequency of Extubation in the Operating Room and Decreases the Time of Mechanical Ventilation after Cardiac Surgery

INTRODUCTION

The delayed extubation of patients undergoing mechanical ventilation (MV) in the postoperative period of cardiac surgery (CS) is associated with mortality. The adoption of spinal anesthesia (SA) combined with general anesthesia in CS influences the orotracheal intubation time (OIT). This study aims to verify if the adoption of SA reduces the time of MV after CS, compared to general anesthesia (GA) alone.

METHODS

Two hundred and seventeen CS patients were divided into two groups. The GA group included 108 patients (age: 56±1 years, 66 males) and the SA group included 109 patients (age: 60±13 years, 55 males). Patients were weaned from MV and, after clinical evaluation, extubated.

RESULTS

In the SA group, considering a 13-month period, 24% of the patients were extubated in the operating room (OR), compared to 10% in the GA group (P=0.00). The OIT was lower in the SA group than in the GA group (SA: 4.4±5.9 hours vs. GA: 6.0±5.6 hours, P=0.04). In July/2017, where all surgeries were performed in the GA regimen, only 7.1% of the patients were extubated in the OR. In July/2018, 94% of the surgeries were performed under SA, and 64.7% of the patients were extubated in the OR (P=0.00). The OIT on arrival at the intensive care unit to extubation, comparing July/2017 to July/2018, was 5.3±5.3 hours in the GA group vs. 1.7±3.9 hours in the SA group (P=0.04).

CONCLUSION

The adoption of SA in CS increased the frequency of extubations in the OR and decreased OIT and MV time.

The Impact of Anesthetic Regimen on Outcomes in Adult Cardiac Surgery: A Narrative Review

Despite improvements in surgical techniques and perioperative care, cardiac surgery still is burdened by relatively high mortality and frequent major postoperative complications, including myocardial dysfunction, pulmonary complications, neurologic injury, and acute kidney injury. Although the surgeon's skills and volume and patient- and procedure-related risk factors play a major role in the success of cardiac surgery, there is growing evidence that also optimizing perioperative care may improve outcomes significantly. The present review focuses on the aspects of perioperative care that are strictly related to the anesthesia regimen, with special reference to volatile anesthetics and neuraxial anesthesia, whose effect on outcome in adult cardiac surgery has been investigated extensively.

Impact of high spinal anesthesia technique on fast-track strategy in cardiac surgery: retrospective study

BACKGROUND AND OBJECTIVES

Although high spinal anesthesia (HSA) has been used in cardiac surgery, the technique has not yet been widely accepted. This retrospective study was designed to investigate the impact of HSA technique on fast-track strategy in cardiac surgery.

METHODS

Elective cardiac surgery cases (n=1025) were divided into two groups: cases with HSA combined with general anesthesia (GA) (HSA group, n=188) and cases with GA only (GA group, n=837). In the HSA group, bupivacaine and morphine were intrathecally administered immediately before GA was induced. Outcomes included fast-track extubation (less than 6 hours), extubation in the operating room, fast-track discharge from the intensive care unit (ICU) (less than 48 hours) and hospital (less than 7 days).

RESULTS

In the HSA group, 60.1% were extubated in less than 6 hours after ICU admission, as compared with 39.9% in the GA group (p<0.001). In the HSA group, 33.0% were extubated in the operating room, as compared with 4.4% in the GA group (p<0.001). LOS in the ICU was less than 48 hours in 67.6% in the HSA group, as compared with 57.2% of those in the GA group (p=0.033). LOS in the hospital was less than 7 days in 63.3% in the HSA group, as compared with 53.5% in the GA group (p=0.084).

CONCLUSIONS

HSA technique combined with GA in cardiac surgery increased the rate of fast-track extubation (less than 6 hours) when compared with GA only.

Impact of intrathecal morphine analgesia on the incidence of pulmonary complications after cardiac surgery: a single center propensity-matched cohort study

Background

Acute pain and systemic opioids may both negatively impact respiratory function after cardiac surgery. This study analyzes the local practice of using intrathecal morphine analgesia (ITMA) with minimal parenteral opioid administration in cardiac surgery, specifically the impact on postoperative pulmonary complications (PPCs).

Methods

Data from adult patients who underwent elective cardiac surgery between January 2002, and December 2013 in a single center were analyzed. Propensity scores estimating the likelihood of receiving ITMA were used to match (1:1) patients with ITMA and patients with intravenous analgesia (IVA). Primary outcome was PPCs, a composite endpoint including pneumonia, adult respiratory distress syndrome, and any type of acute respiratory failure. Secondary outcomes were in-hospital mortality, cardiovascular complications, and length of stay in the intensive care unit (ICU) and hospital.

Results

From a total of 1′543 patients, 920 were treated with ITMA and 623 with IVA. No adverse event consequent to the spinal puncture was reported. Propensity score matching created 557 balanced pairs. The occurrence of PPCs in patients with ITMA was 8.1% vs. 12.8% in patients with IVA (odds ratio, 0.6; 95% CI, 0.40–0.89; p = 0.012). Fewer patients with ITMA had a prolonged stay in the ICU (> 4 days; 16.5% vs. 21.2%, p = 0.047) or in the hospital (> 15 days; 25.5% vs. 31.8%. p = 0.024). In-hospital mortality and cardiovascular complications did not differ significantly between the two groups.

Conclusion

In this study involving cardiac surgical patients, ITMA was safely applied and was associated with fewer PPCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0398-z) contains supplementary material, which is available to authorized users.

High Spinal Anesthesia Enhances Anti-Inflammatory Responses in Patients Undergoing Coronary Artery Bypass Graft Surgery and Aortic Valve Replacement: Randomized Pilot Study

Background

Cardiac surgery induces many physiologic changes including major inflammatory and sympathetic nervous system responses. Here, we conducted a single-centre pilot study to generate hypotheses on the potential immune impact of adding high spinal anaesthesia to general anaesthesia during cardiac surgery in adults. We hypothesized that this strategy, previously shown to blunt the sympathetic response and improve pain management, could reduce the undesirable systemic inflammatory responses caused by cardiac surgery.

Methods

This prospective randomized unblinded pilot study was conducted on 14 patients undergoing cardiac surgery for coronary artery bypass grafting and/or aortic valve replacement secondary to severe aortic stenosis. The primary outcome measures examined longitudinally were serum pro-inflammatory (IL-6, IL-1b, CCL2), anti-inflammatory (IL-10, TNF-RII, IL-1Ra), acute phase protein (CRP, PTX3) and cardiovascular risk (sST2) biomarkers.

Results

The kinetics of pro- and anti-inflammatory biomarker was determined following surgery. All pro-inflammatory and acute phase reactant biomarker responses induced by surgical stress were indistinguishable in intensity and duration between control groups and those who also received high spinal anaesthesia. Conversely, IL-10 levels were markedly elevated in both intensity and duration in the group receiving high spinal anesthesia (p = 0.005).

Conclusions

This hypothesis generating pilot study suggests that high spinal anesthesia can alter the net inflammatory response that results from cardiac surgery. In appropriately selected populations, this may add incremental benefit by dampening the net systemic inflammatory response during the week following surgery. Larger population studies, powered to assess immune, physiologic and clinical outcomes in both acute and longer term settings, will be required to better assess potential benefits of incorporating high spinal anesthesia.

Trial Registration

ClinicalTrials.gov NCT00348920

Effectiveness of combined regional-general anesthesia for reducing mortality in coronary artery bypass: meta-analysis

BACKGROUND AND OBJECTIVES

Neuraxial anesthesia (NA) has been used in association with general anesthesia (GA) for coronary artery bypass; however, anticoagulation during surgery makes us question the viability of benefits by the risk of epidural hematoma. The aim of this study was to perform a meta-analyzes examining the efficacy of NA associated with GA compared to GA alone for coronary artery bypass on mortality reduction.

METHODS

Mortality, arrhythmias, cerebrovascular accident (CVA), myocardial infarction (MI), length of hospital stay (LHS), length of ICU stay (ICUS), reoperations, blood transfusion (BT), quality of life, satisfaction degree, and postoperative cognitive dysfunction were analyzed. The weighted mean difference (MD) was estimated for continuous variables, and relative risk (RR) and risk difference (RD) for categorical variables.

RESULTS

17 original articles analyzed. Meta-analysis of mortality (RD=-0.01, 95% CI=-0.03 to 0.01), CVA (RR=0.79, 95% CI=0.32-1.95), MI (RR=0.96, 95% CI=0.52-1.79) and LHS (MD=-1.94, 95% CI=-3.99 to 0.12) were not statistically significant. Arrhythmia was less frequent with NA (RR=0.68, 95% CI=0.50-0.93). ICUS was lower in NA (MD=-2.09, 95% CI=-2.92 to -1.26).

CONCLUSION

There was no significant difference in mortality. Combined NA and GA showed lower incidence of arrhythmias and lower ICUS.

Is there any benefit in associating neuraxial anesthesia to general anesthesia for coronary artery bypass graft surgery?

BACKGROUND AND OBJECTIVES

The use of neuraxial anesthesia in cardiac surgery is recent, but the hemodynamic effects of local anesthetics and anticoagulation can result in risk to patients.

OBJECTIVE

To review the benefits of neuraxial anesthesia in cardiac surgery for CABG through a systematic review of systematic reviews.

CONTENT

The search was performed in Pubmed (January 1966 to December 2012), Embase (1974 to December 2012), The Cochrane Library (volume 10, 2012) and Lilacs (1982 to December 2012) databases, in search of articles of systematic reviews. The following variables: mortality, myocardial infarction, stroke, in-hospital length of stay, arrhythmias and epidural hematoma were analyzed.

CONCLUSIONS

The use of neuraxial anesthesia in cardiac surgery remains controversial. The greatest benefit found by this review was the possibility of reducing postoperative arrhythmias, but this result was contradictory among the identified findings. The results of findings regarding mortality, myocardial infarction, stroke and in-hospital length of stay did not show greater efficacy of neuraxial anesthesia.