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Indian J Crit Care Med
Indian J Crit Care Med
IJCCM
Indian Journal of Critical Care Medicine : Peer-reviewed, Official Publication of Indian Society of Critical Care Medicine
0972-5229
1998-359X
Jaypee Brothers Medical Publishers

10.5005/jp-journals-10071-24606
Letter to the Editor
Post-cardiac Surgery Delirium: When the Details Matter!
Suresh Varun 1https://orcid.org/0000-0003-2521-1149

Magoon Rohan 2https://orcid.org/0000-0003-4633-8851

1 Department of Anesthesia and Intensive Care, Jaber Al Ahmad Al Sabah Hospital, Kuwait, Arabian Gulf
2 Department of Cardiac-Anaesthesia, Atal Bihari Vajpayee Institute of Medical Sciences (ABVIMS) and Dr. Ram Manohar Lohia Hospital, New Delhi, India
Varun Suresh, Department of Anesthesia and Intensive Care, Jaber Al Ahmad Al Sabah Hospital, Kuwait, Arabian Gulf, Phone: +0091 9041426743, e-mail: varunsureshpgi@gmail.com
2 2024
29 1 2024
28 2 185187
Copyright © 2024; The Author(s).
2024
https://creativecommons.org/licenses/by-nc/4.0/ © The Author(s). 2024 Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
How to cite this article: Suresh V, Magoon R. Post-cardiac Surgery Delirium: When the Details Matter! Indian J Crit Care Med 2024;28(2):185–187.

Keywords

Cardiac surgery
Cognition
Delirium
Melatonin
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pmc Dear Editor,

The meta-analysis by Niyogi et al. suggests a protective role of melatonin-melatonin agonists on post-cardiac surgery delirium, which surfaces at a particularly important time given a heightened recent focus on the pharmacological prevention of postoperative delirium (POD) in peculiarly predisposed settings such as cardiac surgery.1–3 Having included seven studies (six randomized trials and a non-randomized trial), the authors attribute a pooled odds ratio (OR) of 0.44 [95% confidence interval (CI): 0.27–0.71, p = 0.04] supporting a favorable impact of melatonin-melatonin agonists on POD, in a total of 1,179 cardiac surgical patients.1 The research group concurrently elucidates a low overall level of evidence amidst the prevailing risk of bias and/or heterogeneity in their analysis, where we have additional observations to discuss in the matter.

In a meta-analysis involving 13,286 patients, Chen et al. outline the importance of preoperative depression and mild cognitive impairment in determining the risk of POD following cardiac surgery (OR; 95% CI: 3.29; 2.18–4.96, I2 = 0% and 5.40; 2.68–10.89, I2 = 39%, respectively).4 Considering Niyogi et al. do not present the details on the former, we re-evaluated their seven studies focusing on the differences amongst the individual researchers with regards to the preoperative risk assessment.1 For the benefit of the readership, Table 1 enlists how the POD risk factors were accounted for in the seven component studies, with a special emphasis on the objective documentation of the baseline neurocognition. Of note, a 2021 meta-analysis by Li et al. studying the role of dexmedetomidine in preventing post-cardiac surgery delirium formally excluded the existing trials which failed to objectively document the preoperative cognitive status with mini-mental state examination (MMSE) score or other relevant tools.2,3

Table 1 Preoperative cognitive assessment, psychometric tools used and potential confounders evaluated in the candidate studies analyzed by Niyogi et al.1 in their meta-analysis

S. No.	Reference study in the Niyogi et al.1 meta-analysis	Inclusion	Preoperative or baseline assessment	Psychometric tool used to assess delirium and sedation	Other potential confounders evaluated	Main results	
Cognition	Delirium	
1	Reference 13 (Artemiou et al.)	500 patients undergoing elective cardiac surgery, also including off-pump cases	No; preexisting psychiatric diseases were only noted	No	CAM-ICU and RASS score	• EuroSCORE II
• Total BZD, sufentanil consumption
CPB, aortic cross clamp time
LOS	Melatonin reduced the incidence of POD	
2	Reference 14 (Jaiswal et al.)	Patients undergoing elective pulmonary thrombo-endarterectomy	No	No	CAM-ICU score for assessing delirium and RASS score for sedation	• Dose and duration of BZD, opiates and, antipsychotics in ICU
• SOFA score
• MV and LOS	Ramelteon did neither prevent delirium nor cause sedation in the authors’ homogenous cohort of 120 cases	
3	Reference 15 (Ford et al.)	210 adult patients undergoing elective cardiac surgery (CABG or valve surgery)	Yes, patients with dementia as per TICS-M score were excluded (score ≤19)	Patients with preoperative scores ≥15 on alcohol use disorders identification test were excluded	CAM-ICU, MDAS, HADS, TICS-M, RASS scores	• Education, smoking, history of stroke, depression
• Mood and anxiety disorders	Melatonin did not reduce the incidence, duration or severity of delirium in the study cohort	
4	Reference 16 (Sharaf et al.)	50 patients undergoing elective CABG	Yes, patients with low MMSE scores were excluded (score ≤24)	No	ICDSC	• Renal impairment, liver function
• CPB time, aortic cross clamp time
• Total fentanyl consumption	Melatonin reduced the incidence of POD	
5	Reference 17 (Mahrose et al.)	110 patients above 60 years of age, undergoing elective CABG	Patients with mental disorders excluded, however lacking objective assessment	Yes, CAM score estimated as a preoperative baseline	CAM-ICU, RASS	• CPB time, aortic cross clamp time
• Blood transfusion, renal impairment
• Atrial fibrillation
• LOS	Dexmedetomidine use with melatonin reduced the incidence and duration of POD	
6	Reference 18 (Kasnavieh et al.)	140 patients exclusively undergoing elective off-pump CABG	No	No, first CAM-ICU assessment was done on the day of surgery, postoperatively	CAM-ICU score and RASS score	• Education, sleep disorders
• Potassium, sodium, AST, and creatinine	Reduced incidence of delirium found in the melatonin group	
7	Reference 19 (Zadeh et al.)	60 patients undergoing elective CABG	No	No	CAM-ICU score for the incidence and MDAS for the severity of delirium	• Smoking, alcohol consumption and opioid addiction
• EuroSCORE
• Aortic cross-clamp and CPB times	Melatonin reduced the incidence and severity of POD after CABG	
AST, aspartate aminotransferase; BZD, benzodiazepines; CABG, coronary artery bypass graft; CAM-ICU, confusion assessment method in intensive care unit; CPB, cardiopulmonary bypass; EuroSCORE, European system for cardiac operative risk evaluation; HADS, hospital anxiety depression scale; ICDSC, intensive care delirium screening checklist; ICU, intensive care unit; LOS, length of stay; MDAS, memorial delirium assessment scale; MMSE, mini mental state examination; MV, mechanical ventilation; POD, postoperative delirium; RASS, Richmond agitation and sedation scale; SOFA, sequential organ failure assessment; TICS-M, modified telephone interview for cognitive status

Meanwhile, Niyogi et al. declare that the optimal timing of melatonin-melatonin agonists for pharmacological neuroprotection is yet to be explored, it remains to be first highlighted that one of their studies also included patients operated on an off-pump basis with another study exclusively including off-pump coronary artery revascularization (Table 1) which becomes particularly important in the purview of POD, given independent researchers associate the use of cardiopulmonary bypass and its’ duration with post-cardiac surgery delirium.1,5

Orcid

Varun Suresh https://orcid.org/0000-0003-2521-1149

Rohan Magoon https://orcid.org/0000-0003-4633-8851

Source of support: Nil

Conflict of interest: None
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References

1. Niyogi SG Naskar C Singh A Kumar B Grover S Melatonin and melatonin agonists for prevention of delirium in the cardiac surgical ICU: A meta-analysis Indian J Crit Care Med 2023 27 11 837 844 10.5005/jp-journals-10071-24571 37936806
2. Magoon R Mahajan S Jose J DEX, Delirium and Dilemma Braz J Cardiovasc Surg 2023 38 2 305 308 10.21470/1678-9741-2022-0002 36459474
3. Li P Li LX Zhao ZZ Xie J Zhu CL Deng XM et al. Dexmedetomidine reduces the incidence of postoperative delirium after cardiac surgery: A meta-analysis of randomized controlled trials BMC Anesthesiol 2021 21 1 153 DOI: 10.1186/s12871-021-01370-1 34006239
4. Chen H Mo L Hu H Ou Y Luo J Risk factors of postoperative delirium after cardiac surgery: A meta-analysis J Cardiothorac Surg 2021 16 1 113 DOI: 10.1186/s13019-021-01496-w 33902644
5. O'Neal JB Billings FT 4th, Liu X Shotwell MS Liang Y Shah AS et al. Risk factors for delirium after cardiac surgery: A historical cohort study outlining the influence of cardiopulmonary bypass Can J Anaesth 2017 64 11 1129 1137 10.1007/s12630-017-0938-5 28718100
