Higher dose of dexmedetomidine infusion provides better oxygenation and lung mechanics in obese patients undergoing laparoscopic cancer surgeries: A randomized clinical trial

Mohamed Elsayed Hassan; Mohamed Alfattah Wadod

doi:10.4103/bjoa.bjoa_173_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 6 | Issue : 4 | Page : 215-220

Higher dose of dexmedetomidine infusion provides better oxygenation and lung mechanics in obese patients undergoing laparoscopic cancer surgeries: A randomized clinical trial

Mohamed Elsayed Hassan, Mohamed Alfattah Wadod
Department of Anesthesia and Pain Management, National Cancer Institute, Cairo University, Cairo, Egypt

Date of Submission	15-Jun-2022
Date of Decision	09-Aug-2022
Date of Acceptance	16-Aug-2022
Date of Web Publication	31-Oct-2022

Correspondence Address:
Mohamed Elsayed Hassan
Department of Anesthesia and Pain Management, National Cancer Institute, Cairo University, Cairo, Egypt, 34c Yehia Ibrahim, Zamalek, Cairo
Egypt

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/bjoa.bjoa_173_22

Abstract

Background: As a result of the growing international prevalence of overweightness, following then, the proportion of obese people undergoing major surgery increased. Both obesity and laparoscopic cancer surgeries had physiological effect on the respiratory system. Various studies have shown that Dexmedetomidine improves both lung compliance and oxygenation. The goal of the work to compare the effect of two various doses of dexmedetomidine infusion intraoperative on the oxygenation and lung mechanics in obese underwent laparoscopic cancer surgeries. Materials and Methods: This randomized double-blinded, trial was performed on 70 cases who underwent laparoscopic pelviabdominal cancer surgery. Cases were categorized into 2 equal groups. Group A: was given 1 μg/kg body weight dexmedetomidine then 0.5 μg/kg/hour, and group B: received 0.5 μg/kg body weight then 0.3 μg/kg/hour. Dexmedetomidine was administered as a bolus following intubation, then infusion till the end of surgery. Arterial blood gases and lung mechanics were measured at baseline, 30, 60, 90,120 min, and end of surgery. Results: PaO2/FiO2 ratio at 90min, 120min, and the end of surgery and delta PaO2/FiO2 were significantly increased in group A than in group B (P = 0.045, 0.048, and 0.047, respectively). Dynamic compliance at 120 min and at end of surgery were significantly increased in group A in comparison to group B (P = 0.047 and 0.04, respectively). Conclusions: Dexmedetomidine at a higher dose provides better oxygenation, dynamic compliance, lower dead space in obese laparoscopic cancer patients.

Keywords: Dexmedetomidine, laparoscopy, lung compliance, neoplasms, oxygen

How to cite this article:
Hassan ME, Wadod MA. Higher dose of dexmedetomidine infusion provides better oxygenation and lung mechanics in obese patients undergoing laparoscopic cancer surgeries: A randomized clinical trial. Bali J Anaesthesiol 2022;6:215-20

How to cite this URL:
Hassan ME, Wadod MA. Higher dose of dexmedetomidine infusion provides better oxygenation and lung mechanics in obese patients undergoing laparoscopic cancer surgeries: A randomized clinical trial. Bali J Anaesthesiol [serial online] 2022 [cited 2023 Mar 22];6:215-20. Available from: https://www.bjoaonline.com/text.asp?2022/6/4/215/359928

Introduction

Obesity is a difficult disorder defined by an unusually high body fat percentage. It is defined as anybody mass index (BMI) greater than 25 kg/m².^[1] Due to the fact of the growing international prevalence of obesity, following then, the proportion of obese people undergoing major surgery increased.^[2] Laparoscopy has become increasingly popular in surgical management due to its advantages of minimal invasiveness, enhanced cosmetic outcome, and shorter hospital stay, but the influences of pneumoperitoneum and Trendelenburg position on respiratory function throughout laparoscopy may contribute to atelectasis, resulting in severe perioperative pulmonary dysfunction.^[3]

Both obesity and laparoscopic surgeries had physiological effect on the respiratory system.^[4] The variations in lung capacity and respiratory system compliance, could negatively impact pulmonary gas exchange, in conjunction with hindrance of upper airways and sleep- breathing disorder required to be evaluated carefully in the perioperative time.^[5] Dexmedetomidine is a selective -2 agonist with a variety of clinical applications in anaesthesia and the intensive care unit. Additionally its cardiovascular and sedative properties, dexmedetomidine has favorable respiratory effects in chosen groups of humans patients.^[6]

In both obese cases with restrictive lung illnesses, and chronic obstructive pulmonary disease (COPD) cases performing lung cancer surgery, dexmedetomidine showed better improvement in oxygenation, lung compliance, decreased plateau pressure, dead space, blood pressure, and HR at drug infusion end.^[7],[8] These difficulties in the obese laparoscopic cancer case have resulted in a certain focus on the clinical treatment approach for lung mechanics and oxygenation in case position at initiation and under anesthesia. Therefore, we established this study to compare the combined impact of two distinct dosages of dexmedetomidine intraoperatively on oxygenation and lung mechanics in obese cases underwent laparoscopic cancer surgery.

Materials and methods

This randomized double-blinded, trial performed on 70 cases aged 18–60 years, ASA II with a BMI of >25 kg/m² had laparoscopic pelviabdominal cancer surgery at National Cancer Institute. The investigation was done with ethical committee permission and registration at Clinical Trials Registration (registry number NCT04730375 dated 29 January 2021) from January 2021 to February 2022. Prior to recruitment, all subjects provided written informed permission. Cases with heart failure or heart block, arrhythmia, severe kidney or liver impairment, and patients with forced expiratory volume in 1 sec/ forced vital capacity (FEV1)/FVC less than 70% were excluded.

Concealment was accomplished utilizing opaque sealed envelopes. Cases were randomized into two equal groups by a computer-generated sequence. Group A: received dexmedetomidine of 1 μg/kg then 0.5 μg/kg/hour, group B: received 0.5 μg/kg then 0.3 μg /Kg/hour in group B. Dexmedetomidine was administered as a bolus following intubation, then infusion till the end of surgery.

The anesthesiologist, who participate with group assignment or data gathering, experiment procedure and the researcher’s outcome assessor was unaware of the group assignment and was not present during the blocks’ execution. To ensure the investigator’s blinding, the study medication was produced, and the rate of injection determined by a research assistant. Full history taking, type of surgery, pulmonary function assessment (first forced expiratory volume, forced vital capacity) and duration of surgery were recorded preoperatively.

When the patient is referred to the operation room, monitors were attached, e.g., electrocardiogram, capnography, pulse oximetry and noninvasive blood pressure monitor at room temperature. Arterial canula for ABG and invasive monitoring was inserted. For all medicines except neostigmine, dosage was estimated using lean body weight (whole body weight was utilized).^[9]

Fentanyl (2 μg/kg) Propofol (2 mg/kg) and were used to induce anesthesia. Following anesthesia induction, an endotracheal tube was introduced with the assistance of rocuronium (0.5 mg/kg). Sevoflurane (2%) and rocuronium (0.1 mg/kg) incremental were used for maintenance. The following parameters were used to pressure-controlled ventilation: A low tidal volume (6–8 ml/kg), volume-controlled ventilation, a respiratory rate and an 8–10 mmH₂O positive end-expiratory pressure (PEEP), and adequate to keep an end-tidal CO₂ of 30–35 mmHg. In our cases, no recruiting maneuvers were performed.

At the conclusion of the procedure, sevoflurane was ceased, and neostigmine (0.05 mg/kg) and atropine (0.02 mg/kg) used for changing any lingering neuromuscular inhibition The case was then extubated and discharged in post-anesthesia care unit (PACU). Dynamic lung compliance was assessed by Maquet anesthesia machine as: tidal volume/ (peak airway pressure PEEP). The static lung compliance was determined as: Tidal volume/ (plateau pressure - PEEP). Physiological dead space was determined by Hardman and Aitkenhead equation:^[10] Vd/Vt = 1.14 (PaCO2–EtCO2)/ PaCO2–0.005.

Patient baseline characteristics, type, and duration of surgery. Baseline pulmonary functions PH, HCO3 were recorded. PaO₂/FiO₂, PaCO₂ static and dynamic compliance and dead space were measured at baseline following intubation before infusion and every 30 minutes till surgery ended.

HR and MAP were measured at baseline and every 15 minutes till surgery ended. Postoperative complications (bradycardia, hypotension, postoperative nausea, vomiting and atelectasis by computed tomography (CT) scan and pain at PACU were assessed. The primary result was oxygenation at the final of surgery, while the secondary consequences were lung compliance (static and dynamic), hemodynamics, intraoperative oxygenation and dead space.

Sample size calculation was done by G*power 3.1.9.2 (Universitat Kiel, Germany). The mean (±SD) delta PaO₂/FiO₂ ratio between baseline and 90 minutes (the primary outcome) was - 32 (±43) with dexmedetomidine infusion 1 µg according to a previous study and expected to be 75% less with dexmedetomidine infusion 0.5 µg (difference 24).^[11] With 80% power, 95% confidence limit, and Five participants have been added to compensate for dropouts, 35 patients were enrolled in each group.

SPSS version 27.0 (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY: IBM Corp) utilized for statistical analysis. To determine the normality of the data distribution, the Shapiro-Wilks test and histograms used. The unpaired student t-test utilized to establish the mean and standard deviation (SD) of quantitative parametric data. The Mann Whitney-test used to analyse non-parametric quantitative data presented as median and interquartile range (IQR). Qualitative variables reported as frequencies and percentages (percentages) and analysed utilizing the Chi-square or Fisher’s exact test, as appropriate. A p-value of 0.05 with two tails is deemed statistically significant.

Results

In this trial, 91 cases were evaluated for eligibility, 16 cases did not match with the conditions, and 5 cases refused to join to the trial. The remaining 70 cases were equally classified into 2 groups, followed up and statistically analyzed [Figure 1]. Baseline characteristics, kind and period of surgery were insignificantly different among the studied groups. Baseline pulmonary function test (FVC (%), FEV1/FVC) were insignificantly different between both groups [Table 1].

Figure 1: CONSORT flow diagram of the participants through each stage of the trial

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Table 1: Patient baseline characteristics, type, and duration of surgery of the studied groups

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PaO₂/FiO₂ was insignificantly different at baseline, 30min, and 60min and was substantially increased in group A than B at 90min, 120min, and at the surgery end. Meanwhile, delta PaO₂/FiO₂ was substantially enhanced in group A compared to B (P = 0.002), as seen in [Table 2]. Dynamic compliance was insignificantly different between both groups at baseline, 30 min, 60 min, and 90 min and was significantly increased in group A than B at 120 min and at the end of surgery. Delta dynamic compliance was significantly increased in group A compared to B. Static compliance and PaCO₂ were insignificantly different at all times of measurement between both groups.

Table 2: Oxygenation and ABG of the studied patients

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Dead space was insignificantly different between both groups at baseline, 30min, 60min, and 90min, but was considerably decrease in group A than B at 120min and at the end of surgery. Delta dead space was significantly reduced in group A than B. [Figure 2] shows HR and MAP were considerably decreased in group A than B from 30min to the end of surgery (P < 0.05). All complications (bradycardia, hypotension, nausea, vomiting and atelectasis) and pain at PACU were insignificantly different between studied groups [Table 3].

Figure 2: Heart rate and mean arterial blood pressure of the studied patients

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Table 3: Complications in the studied patients

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Discussion

Dexmedetomidine has shown promise as an organ protecting agent.^[12] Intraoperative dexmedetomidine administration enhanced the quality of oxygenation and lung mechanics in cases having lung excision surgery.^[13] Our results showed that group (A) (high dose of dexmedetomidine) was significantly better than group (B) in oxygenation, dynamic compliance, dead space. Complications as bradycardia, hypotension, nausea, vomiting and atelectasis and Visual Analogue Scale (VAS) score were insignificantly different between studied groups.

Dexmedetomidine has different mechanisms that participate in its respiratory effect on oxygenation and lung mechanics. Dexmedetomidine leads to bronchodilatation by blocking histamine-induced bronchoconstriction if administrated parentally.^[14] Dexmedetomidine in moderate doses regulates the secretion of inflammatory mediators and cytokines like C-reactive protein, IL-10, and tumor necrosis factor, so it protects the lungs against inflammatory pulmonary injury during laparoscopic surgery.^[15]

Dexmedetomidine had an inhibitory action of inhalational anesthetic drugs on hypoxic pulmonary vasoconstriction and increased the perfusion of ventilated lungs via activation of alpha-2 receptors in vascular smooth muscles.^[16] Therefore, dexmedetomidine reduces intrapulmonary shunt enhance ventilation/perfusion ratio and accordingly enhance oxygenation.^[17]

Hasanin et al.^[18] investigated 42 obese patients scheduled with bariatric surgery dexmedetomidine group, demonstrated significantly improved PaO₂/FiO₂ ratio and increased lung compliance at drug administration end in comparison to the controls. At the ending of the administration, the dexmedetomidine group had a lower plateau pressure, dead space than the control group.

Also, Lee et al.^[7] investigated 50 patients who had thoracoscopic surgery with moderate COPD and reported comparable improvements in oxygenation and lung mechanism in COPD cases performed lung cancer surgery as at PACU, PaO₂ /FIO₂ ratio was increased substantially in the dexmedetomidine group in comparison to the controls. Asri et al.^[19] stated an enhancement in oxygenation of one-lung ventilation with the lower dose of dexmedetomidine (at 0.3 µg/kg/h).

There is a lack of studies that focused on effect of high doses of dexmedetomidine intraoperatively on lung mechanics and oxygenation in overweighting laparoscopic cancer cases. The main limitation of this study was the sample size was relatively insufficient to prove our secondary outcomes. Furthermore, we excluded ASA III and above patients, and the study did not involve a control group.

Conclusion

Dexmedetomidine at a higher dose provides better oxygenation, dynamic compliance, lower dead space in obese laparoscopic cancer patients.

Acknowledgement

Not applicable.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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