LETTER TO THE EDITOR |
https://doi.org/10.5005/jp-journals-10049-2049 |
Anesthesia in the Obese: All About Safety!
1Department of Anesthesia, Critical Care and Pain Medicine, All India Institute of Medical Sciences, New Delhi, India
2Department of Anesthesia, Atal Bihari Vajpayee Institute of Medical Sciences and Dr Ram Manohar Lohia Hospital, New Delhi, India
3Department of Anesthesia and Intensive Care, Jaber Al Ahmad Al Sabah Hospital, Arabian Gulf, Kuwait
Corresponding Author: Varun Suresh, Department of Anesthesia and Intensive Care, Jaber Al Ahmad Al Sabah Hospital, Arabian Gulf, Kuwait, Phone: +96565751020, e-mail: varunsureshpgi@gmail.com
How to cite this article: Choudhary N, Magoon R, Suresh V. Anesthesia in the Obese: All About Safety! Res and Innov Anesth 2024;9(1):33–34.
Source of support: Nil
Conflict of interest: None
Dear Editor,
We read with great interest the case report by Chellam et al. outlining successful anesthetic management of a morbidly obese patient [body mass index (BMI) of 71.1 kg/m] undergoing a gynecological procedure, with intraoperative use of high-flow nasal oxygenation (HFNO) following a failed subarachnoid block.1 The authors, having appropriately highlighted the clinical utility of HFNO in this peculiar scenario, note there remain caveats which require discussion specific to high-risk patients, especially in nonbariatric settings like theirs.
Firstly, the STOP-Bang questionnaire is a routinely used screening tool for obese patients at risk of obstructive sleep apnea (OSA) during the preanesthetic checkup.2 This questionnaire not only helps in the diagnosis of OSA but also aids in grading its severity based on the scores. A score of ≥5 points toward moderate-to-severe OSA.2 While the authors have attended to some of the parameters of this scoring system, a careful assessment and scoring in this patient would have added to the scientific discussion on the risks of perioperative pulmonary complications. Also, the authors have categorically mentioned the arterial oxygen saturation value of 92%, which, in light of the aforementioned facts, affirms the need for the scoring system. Previous studies have found a negative correlation between oxygen saturation (pulse oximeter reading) and higher OSA scores, which helped in predicting meaningful hypoxia before the actual event in sedated patients.3
Secondly, there is no clarity on the dose calculation of various anesthetic agents, which becomes a very crucial aspect of anesthetic management in this cohort. Indeed, patients with high BMI are known to be overly sensitive to anesthetic agents; therefore, it is important that the doses are calculated carefully (based on ideal, adjusted, or total body weight) and administered in a titrated manner to achieve the required effect. Anesthesia was induced using a combination of propofol with ketamine. Although with ketamine, the bispectral index value (BIS) is not a reliable indicator of the depth of anesthesia, despite this, applying the BIS electrode would have provided some information to guide the administration of safe anesthesia in these high-risk patients. Also, the dose and timing of antihypertensives could have further enhanced our understanding of intraoperative hemodynamics.
Lastly, the index case showcases the usefulness of HFNO in maintaining intraoperative oxygenation in obese patients under anesthesia. However, Hung et al.4 in their meta-analysis on the efficacy of HFNO in the prevention of peri- and postprocedural hypoxia in obese patients found that HFNO only increased the safe apnea period [mean difference (MD) = 73.88 seconds, p = 0.0004] in comparison to the control group (conventional oxygen therapy and noninvasive ventilation). They did not find any significant difference in the risk of periprocedural hypoxemia as observed from the lowest saturation of peripheral oxygen (MD = 0.09%, p = 0.95); partial pressure of arterial carbon dioxide (MD = −6.71%, p = 0.2); partial pressure of oxygen (MD = −8.13 mm Hg, p = 0.86); end-tidal carbon dioxide (MD = −0.28 mm Hg, p = 0.07); and the postprocedural partial pressure of oxygen in arterial blood/fraction of inspiratory oxygen concentration ratio (MD = 41.76, p = 0.58).4 Therefore, more robust studies are required before propagating the clinical utility of such techniques, especially in predisposed subjects. The report requires careful consideration before extrapolating this clinical experience to all obese patients.
ORCID
Nitin Choudhary https://orcid.org/0000-0002-8933-1222
Rohan Magoon https://orcid.org/0000-0003-4633-8851
Varun Suresh https://orcid.org/0000-0003-2521-1149
REFERENCES
1. Chellam S, Dalal K, Toal PV. Anesthesia management of a morbidly obese patient in a nonbariatric setup using HFNO: a case report. Res Inno Anesth 2023;8(02):63–65. DOI: 10.5005/jp-journals-10049-2038
2. Chung F, Abdullah HR, Liao P. STOP-Bang questionnaire: a practical approach to screen for obstructive sleep apnea. Chest 2016;149(03):631–638. DOI: 10.1378/chest.15-0903
3. Yun M, Kim J, Ryu S, et al. The correlation between the STOP-Bang score and oxygen saturation during spinal anesthesia with dexmedetomidine sedation. Anesth Pain Med (Seoul) 2021;16(03):305–311. DOI: 10.17085/apm.21011
4. Hung KC, Ko CC, Chang PC, et al. Efficacy of high-flow nasal oxygenation against peri- and post-procedural hypoxemia in patients with obesity: a meta-analysis of randomized controlled trials. Sci Rep 2022;12(01):6448. DOI: 10.1038/s41598-022-10396-5
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