Comparison of incidence of gastroesophageal reflux and regurgitation associated with timing of removal of the laryngeal mask airway: on appearance of signs of rejection versus after recovery of consciousness

Optimum time of LMA ProSeal removal in adult patients undergoing isoflurane anesthesia: A randomized controlled trial

Background and Aims:

Optimum timing of laryngeal mask airway (LMA) removal after general anesthesia with isoflurane is debatable. The objective was to investigate the potential benefits of removing LMA ProSeal at ≤0.4 Minimum alveolar concentration (MAC) isoflurane over awake and “deep plane” extubation after short duration laparoscopic gynecological surgery.

Material and Methods:

In this prospective randomized trial 90 adult female patients undergoing elective laparoscopic surgery under general anesthesia using LMA ProSeal™ as airway device were included. At the end of surgery, LMA ProSeal™ was removed when the patient was awake, could open mouth following verbal command (Group A); at MAC ≤0.4 (Group B); or at MAC of 0.6 (Group C). Adverse airway events like nausea, vomiting, airway obstruction, coughing, bucking, laryngospasm were noted. Statistical analyses were done by SPSS statistical software (IBM SPSS Statistics for Mac OS X, Version 21.0. IBM Corp, Armonk, NY).

Results:

Baseline demographic characteristics were comparable in all three groups. Coughing or bucking at the time of LMA removal was higher in group A (P = 0.004). Snoring and airway obstruction after LMA removal was significantly higher in group C compared to group A and group B (P = 0.002 and P = 0.011, respectively). There was significant change in mean arterial pressure and heart rate between before and after LMA removal on group A (P = 0.008 and P < 0.001, respectively) but not in other groups.

Conclusion:

MAC ≤0.4 can be considered optimum depth of anesthesia for removal of LMA Proseal in adult patients undergoing isoflurane anesthesia.

Early versus late removal of the laryngeal mask airway (LMA) for general anaesthesia

BACKGROUND

The laryngeal mask airway (LMA) is a safe and effective modality to maintain the airway for general anaesthesia during surgical procedures. The LMA is removed at the end of surgery and anaesthesia, when the patient maintains an adequate respiratory rate and depth. This removal of the LMA can be done either when the patient is deep under anaesthesia (early removal) or only after the patient has regained consciousness (late removal). It is not clear which of these techniques is superior.

OBJECTIVES

The objective of this review was to compare the safety of LMA removal in the deep plane of anaesthesia (early removal) versus removal in the awake state (late removal) for participants undergoing general anaesthesia.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 8); MEDLINE (1966 to August 2014); EMBASE (1980 to August 2014); LILACS (1982 to August 2014); CINAHL (WebSPIRS; 1984 to August 2014); and ISI Web of Science (1984 to August 2014). We searched for ongoing trials through various trial registration websites. In addition, we searched conference proceedings and reference lists of relevant articles.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) on adults and children undergoing elective general anaesthesia using the LMA, that compared early removal of the LMA (defined as removal of the LMA in the deep plane of anaesthesia) versus late removal of the LMA (defined as removal of the LMA after the patient is awake).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. We used a random-effects model to generate forest plots from the data.

MAIN RESULTS

We identified a total of 9188 citations and included 15 RCTs conducted on 2242 participants in this review. All trials used the LMA Classic in American Society of Anesthesiologists (ASA) physical status I or II for patients undergoing elective general anaesthesia. Children were enrolled in 11 trials and adults in five trials. None of the trials were of high methodological quality. Eight of the 15 studies had adequate generation of random sequence, whereas only one trial had adequate concealment of random sequence. Three trials had blinded the outcome assessor. Thus, the majority of the studies appeared to have a high risk of bias in the study design.Using the GRADE approach, we found low quality evidence that the risk of laryngospasm was similar with early removal of the LMA (3.3%) versus late removal (2.7%): risk ratio (RR) 1.23, 95% confidence interval (CI) 0.74 to 2.03; 11 trials, 1615 participants. The quality of evidence was very low that the risk of coughing was less after early removal (13.9%) than late removal (19.4%): RR 0.52, 95% CI 0.29 to 0.94; 11 trials, 1430 participants. The quality of evidence for the risk of desaturation was also very low; there was no difference between early removal (7.9%) and late removal (10.1%): RR 0.68, 95% CI 0.4 to 1.16; 13 trials, 2037 participants. We found low quality evidence that the risk of airway obstruction was higher with early removal (15.6%) compared to late removal of the LMA (4.6%): RR 2.69, 95% CI 1.32 to 5.5; eight trials, 1313 participants.

AUTHORS' CONCLUSIONS

This systematic review suggests that current best evidence comparing early versus late removal of the LMA in participants undergoing general anaesthesia does not demonstrate superiority of either intervention. However, the quality of evidence available is either low or very low. There is a paucity of well designed RCTs and a need for large scale RCTs to demonstrate whether early removal or late removal of the LMA is better after general anaesthesia.

A sequential examination of parent-child interactions at anesthetic induction

Parental presence is often employed to alleviate distress in children within the context of surgery under general anesthesia. The critical component of this intervention may not be the presence of the parent per se, but more importantly the behaviors in which the parent and child engage when the parent is present. The purpose of the current study was to examine the sequential and reciprocal relationships between parental behaviors and child distress during induction of general anesthesia. Participants were 32 children (3-6 years) receiving dental surgery as a day surgery procedure, and their parents. A modified Child Adult Medical Procedures Interaction Scale-Revised was used to code parent and child behaviors. Initial child distress led to increased parental provision of reassurance and decreased provision of physical comfort. Our findings may inform the development of preoperative preparation programs whereby parents can be appropriately educated about what behaviors will be helpful/unhelpful for their child during induction of general anesthesia.

The ProSeal laryngeal mask airway

The ProSeal LMA is a major advance over the Classic LMA because of the following reasons: it allows ventilation at much higher airway pressures; it protects the lungs from aspiration and the stomach from gastric insufflation; it facilitates passage of a gastric tube and monitoring devices into the esophagus; it can be inserted like the Classic or Intubating LMA; it has its own built-in bite block; malposition is detected more readily; and, through use of techniques such as gum elastic bougie-guided insertion, correct positioning is almost guaranteed. The ProSeal can be considered a replacement device for the Classic LMA, but the Flexible LMA is still preferable for most intraoral procedures, and the Intubating LMA is still preferable whenever intubation is required. Limitations are that it is slightly more difficult to insert and requires more careful thought to use optimally.

Effect of laryngeal mask airway on esophageal motility during general anesthesia

STUDY OBJECTIVES

To determine whether the Laryngeal Mask Airway (LMA) triggers the pharyngo-esophago-gastric reflex during general anesthesia by comparing the esophageal motility of patients with the LMA and endotracheal tube (ETT) in place.

DESIGN

Randomized clinical trial.

SETTING

Operating room and recovery room of a tertiary-care referral hospital.

PATIENTS

50 adult ASA physical status I and II patients scheduled for elective orthopedic surgery.

INTERVENTIONS

All patients received a standardized general anesthetic technique, then were allocated randomly to the LMA (n = 30) or ETT (n = 20) groups.

MEASUREMENTS AND MAIN RESULTS

The esophageal manometric inputs were recorded continuously using an ambulatory esophageal manometric recorder and divided into five perioperative phases (preanesthesia, induction, surgery, LMA, or ETT rejection and arousal phase). The LMA or ETT was removed at the end of the surgery, when the patient was awake. An awake state was defined as the presence of the following clinical signs: swallowing, bucking, struggling, straining, and restlessness. The esophageal peristaltic wave percent and esophageal contraction frequency were significantly decreased during induction, surgery, and the LMA or ETT rejection and arousal phases compared with the preanesthetic phases in both the LMA and ETT groups. However, there were no significant group differences in any corresponding perioperative phases.

CONCLUSION

During the general anesthetic period before the arousal phase in this study, a LMA does not provoke significantly different esophageal peristalsis compared with an ETT. Thus, the LMA is unlikely to stimulate the pharyngo-esophago-gastric reflex during that period.

Mechanisms of gastroesophageal reflux and gastroesophageal reflux disease

Gastroesophageal reflux is a physiological phenomenon, occurring with different severity and duration in different individuals. Reflux occurs when this normal event results in the occurrence of symptoms/signs or complications. The pathophysiology of gastroesophageal reflux is complex and diverse, since it is influenced by factors that are genetic, environmental (e.g., diet smoking), anatomic, hormonal, and neurogenic. However, many mechanisms remain incompletely understood. Future research should focus on a better understanding of the physiology of the upper and lower esophageal sphincters, and of gastric motility. The afferent and efferent neural pathways and neuropharmacologic mediators of transient lower esophageal sphincter relaxations and gastric dysmotility require further study. The role of anatomic malformations such as hiatal hernia in children has been underestimated. While therapeutic possibilities are greater in number and largely improved, the outcomes of some treatments are far from satisfactory in many cases. In addition to development of new forms of treatment, research should address better use of currently available medical and surgical treatments.

Gastroesophageal reflux and aspiration of gastric contents in anesthetic practice

General anesthesia may predispose patients to aspiration of gastroesophageal contents because of depression of protective reflexes during loss of consciousness. In addition, some patients may be at increased risk of pulmonary aspiration because of retention of gastric contents caused by pain, inadequate starvation, or gastrointestinal pathology resulting in reduced gastric emptying and gastroesophageal reflux. Despite increasing knowledge of the problems associated with aspiration, the relatively small incidence and associated mortality rates in the perioperative period do not appear to have changed markedly over the last few decades. In this review article, the physiological factors associated with an increased risk of gastroesophageal reflux and aspiration are considered together with some of the methods that are used to prevent aspiration. In particular, preoperative starvation, the use of drugs designed to increase gastric pH, recent developments in airway devices, and appropriate application of cricoid pressure are critically appraised.