Effects of Low-Flow Sevoflurane Anesthesia on Pulmonary Functions in Patients Undergoing Laparoscopic Abdominal Surgery

Precision in practice: An audit study on low-flow anesthesia techniques with desflurane and sevoflurane for cost-effective and sustainable care

Introduction

In the backdrop of escalating healthcare costs and an increasing focus on resource optimization, this audit study delves into the realm of anesthesia management, specifically exploring the application of low-flow anesthesia (LFA). The primary objective was to assess adherence to hospital standards and evaluate the economic implications of LFA (<1 L/min).

Materials and Methods

This retrospective audit focused on 700 adult patients undergoing elective surgeries with general anesthesia. Data sources included anesthesia records, electronic recording systems, and audits by a dedicated team. Fresh gas flow rates (FGFRs), minimum alveolar concentration (MAC), and volatile anesthetic consumption were analyzed. Cost comparisons between low-flow and high-flow anesthesia were conducted, employing specific cost per milliliter metrics.

Results

The average FGFR during the maintenance phase was found to be 0.45 ± 0.88 L/min. Adherence to hospital standards was notably high, with 94.29% of patients being maintained on low-flow gas rates. The differences in anesthetic consumption between low-flow and high-flow FGFR were statistically significant for both desflurane (12.17 ± 10.84 ml/MAC hour versus 43.12 ± 27.25 ml/MAC hour) and sevoflurane (3.48 ± 7.22 ml/MAC hour versus 5.20 ± 5.20 ml/MAC hour, P < 0.001). The calculated savings per patient with low-flow desflurane and sevoflurane anesthesia compared to high flow were found to be 109.25 AED and 6.74 AED, respectively.

Conclusion

This audit advocates for the widespread adoption of LFA as a standard practice. Beyond aligning with hospital standards, the study highlights the multi-faceted benefits of LFA, encompassing economic savings, environmental safety, and enhanced patient care.

Effects of different fresh gas flows on carboxyhemoglobin levels: non-invasive carbon monoxide monitoring: A randomized clinical trial

OBJECTIVES

To observe the effect of different fresh gas flows (FGF) on carboxyhemoglobin (COHb) levels non-invasively and continuously and to determine the contribution of the smoking status to intraoperative carbon monoxide (CO) accumulation and respiratory complications.

METHODS

A total of 64 patients were included in the study. Carboxyhemoglobin level was monitored non-invasively from the fingertip. Patients were divided into 2 according to the FGF as low-flow anesthesia (LFA; Group L) and high flow anesthesia (Group H). Each group was divided again into 2 groups as smokers and non-smokers. Carboxyhemoglobin and and the respiratory complications that occurred in the post-anesthesia care unit were recorded.

RESULTS

The mean COHb values were significantly higher in Group L between 30th and 210th minutes. Furthermore, in Group L, intraoperative COHb levels were significantly higher in smokers compared to non-smokers in all periods. In group H, no difference was observed between smokers and non-smokers in terms of COHb levels after 60 minutes and also preoperative COHb levels of the patients developed respiratory complication was higher.

CONCLUSION

If the CO₂ absorbent is properly preserved in patients who are administered LFA, there will be no risk of CO accumulation even in chronic smokers.ClinicalTrials.gov REG. No.: NCT04832256.

The effect of low flow anesthesia on hemodynamic and peripheral oxygenation parameters in obesity surgery

Objectives:

To investigate the effects of low-flow anesthesia on hemodynamic parameters and recovery from anesthesia in obese individuals undergoing laparoscopic surgery.

Methods:

This randomized-controlled and prospective study included 44 obese patients who underwent laparoscopic sleeve gastrectomy operation. The patients were randomly allocated into 2 groups as low-flow and high-flow anesthesia. Further, the groups compared in terms of hemodynamic parameters, anesthesia recovery times, operation times, and arterial blood gas parameters.

Results:

The groups were similar with respect to demographic data. Heart rate, peripheral oxygen saturation, arterial blood pressure measurements, end-tidal, and CO₂, lactate levels measurements were similar in both groups during the entire procedure. There was also no statistically significant difference in terms of arterial blood gas parameters or anesthesia recovery periods.

Conclusion:

Low-flow anesthesia in laparoscopic obesity surgery seems to be safer compared to high-flow anesthesia in terms of the adequacy of tissue perfusion, depth of anesthesia, and postoperative recovery.

Randomized double-blind trial comparing effects of low-flow vs high-flow anesthesia on postoperative lung functions using respirometer

Background and Aims:

Modern anesthetic practice utilizes low-flow anesthesia with evolving evidence on its pulmonary effects. Studies comparing measurement of vital capacity and inspiratory reserve volume using respirometer in both low-flow and high-flow anesthesia are sparse. We evaluated the effects of low-flow and high-flow anesthesia on postoperative pulmonary functions using respirometer.

Material and Methods:

This was a prospective randomized double blind study wherein One hundred and ten patients undergoing peripheral surgeries under general anesthesia were allocated into two groups Group I- Low-flow anesthesia with O2 + N2O + Sevoflurane (0.5L + 0.5L + 3.5%) and Group II- High-flow anesthesia with O2 + N2O + Sevoflurane (2L + 2L + 2%). The difference in vital capacity (VC), inspiratory reserve volume (IRV), and peak expiratory flow rates (PEFR) from the preoperative period were compared in both the groups postoperatively.

Results:

The difference in VC, IRV, and PEFR measured in both the groups between the preoperative and postoperative period were found to be similar and statistically insignificant (P - 0.173, 1.00 and 0.213 respectively). The difference in single breath count (SBC), breath holding time (BHT), and respiratory rates (RR) were also similar in both the groups (P – 0.101, 0.698, and 0.467) respectively.

Conclusions:

The pulmonary effects of low-flow anesthesia are comparable with the high-flow ones in patients undergoing elective surgeries under general anesthesia.

Changes in Gas Composition during Low Flow Anaesthesia without Nitrous Oxide

INTRODUCTION

Low flow anaesthesia utilising Oxygen (O₂) and Nitrous Oxide (N₂O) mixture carries a risk of hypoxia, but avoiding N₂O results in increased analgesic and volatile anaesthetic agent requirement.

AIM

This study attempted to find the lowest Fraction of inspired Oxygen (FiO₂) levels achieved with a mixture of 300 mL/min each of O₂ and medical air over two hours and to compare the overall analgesic requirement and cost while using similar flows of N₂O and O₂, respectively.

MATERIALS AND METHODS

A prospective observational study was conducted between March 2015 and June 2016 at the Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India. Patients of American Society of Anaesthesiologists (ASA) Grade 1 and 2 undergoing surgery under general anaesthesia with an endotracheal tube were included in the study, in two groups of 40 each. In the initial ten minutes following induction of anaesthesia, both groups received high Fresh Gas Flows (FGF) of 3 L/min each (Group O: medical air and oxygen; Group N: N₂O and oxygen), following which the FGF rates were reduced to 300 ml/min each. Any value of FiO₂ lesser than 0.3 during the duration of anaesthesia was considered to render the technique unsafe for clinical use. SPSS software version 20.0 was used to generate data and figures.

RESULTS

The lowest FiO₂ recorded was 0.33 in Group O and 0.3 in Group N which occurred at the end of two hours. Mean analgesic requirement was significantly higher in Group O compared to Group N (151.85 μg, 124.85 μg; p-value=0.004) with a 62% increase in the cost incurred.

CONCLUSION

The use of medical air and oxygen in flows of 300 ml/min each following initial high flows of 3 L/min appears to be a safe technique. However, this combination was associated with an increase in the cost of anaesthesia and in the need for additional intra-operative analgesia.