Effectiveness of ketamine gargle in reducing the incidence of postoperative sore throat in patients undergoing airway instrumentation: a systematic review protocol

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Abstract

Review question/objective

The objective of this review is to identify the effectiveness of ketamine gargle in comparison to placebo in reducing postoperative sore throat for patients undergoing airway instrumentation.

Background

Postoperative sore throat (POST) remains a frequent complaint for patients after airway instrumentation yet it takes very little pre-intervention to reduce the effects of throat soreness.1-5 Airway instrumentation is defined as manipulation of the airway to facilitate insertion of an object into the airway for assisting or maintaining breathing and/or for diagnostic purposes.5 POST may be perceived by health care providers as a minor side effect associated with the insertion of airway instrumentation; however POST can be a distressing point of focus for most patients that could diminish an overall positive surgical experience.2 Sore throat is a general term that encompasses many different symptoms. For the purposes of this review, the term 'sore throat' will include specific symptoms such as: dysphagia (difficulty in swallowing), dysphonia (disorders of the voice), hoarseness, continuous throat pain and pharyngeal dryness.6

Background

"Sore throat” can result from damage and/or irritation to the tracheal mucosa due to the introduction of an instrument to the airway.1,5 Various instruments are inserted into the airway during surgical or diagnostic procedures, including laryngoscopes, laryngeal mask airways, oral airways, suctioning devices or fiber optic equipment, for visualization of the airway. Anesthesia providers maintain or assist an anesthetized patient's respirations with an endotracheal tube (ETT) or laryngeal mask airway (LMA). Laryngoscopy for ETT placement involves the insertion of a hard metal or plastic instrument into the oropharynx with subsequent manipulation of the epiglottis for direct visualization of the vocal cords. Laryngoscopy with subsequent insertion of an ETT can result in irritation to any part of the pharynx, the larynx or the trachea.5 Sore throat is often highest after tracheal intubation; however, the incidence of POST has also been documented after the use of LMA.6 The LMA is a supraglottic airway device that sits above the glottis providing a tight seal around the trachea. LMA insertion involves sliding the soft plastic device backwards along the roof of the oral cavity until resistance is felt. LMA insertion can result in irritation to the pharynx above the glottis.5

Background

In a study performed by Lehmann, Monte, Barach and Kindler, postoperative complaints were evaluated in 12,276 patients and POST was rated as the second highest patient complaint of dissatisfaction.3 A non-randomized prospective study conducted by Biro, Seifert and Pasch noted a 40% incidence of sore throat complaints amongst 809 patients analyzed.2 Researchers have attempted to provide patients with a simple, yet effective, intervention to reduce POST that is consistent with the provision of adequate and quality care by the anesthesia provider.2,3 Studies have analyzed the effectiveness of reducing POST with various methods including the use of a smaller sized endotracheal tube, the preoperative administration of a lidocaine spray, and the application of lidocaine or betamethasone gel to the distal portion of the endotracheal tube.1,2,7,8 While these interventions have shown some effectiveness in reducing POST, not one intervention has been completely effective. For this reason, the exploration of alternative techniques is indicated.

Background

Ketamine gargle is a newly proposed adjunct for reducing the incidence of POST in anesthesia literature. The gargle is hypothesized to provide analgesia due to its inhibition of N-methyl-D-aspartate (NMDA) receptors and agonist activity at opioid receptors located in the oral and upper respiratory tract mucosa.9-11 As cited by Quibell et al.,11 ketamine rinse has been shown to be a useful treatment in radiation-induced oral mucositis. In a study by Ryan, Lin and Atayee,12 ketamine mouthwash - 20 mg/5 mL - was utilized for the treatment of refractory oral mucositis pain, with success in five of the eight patients studied. These authors cite two additional studies in which ketamine rinse - at doses of 20 mg/5 mL and 40 mg/30 mL - was successfully utilized for the treatment of oral mucositis pain and prevention of post-operative sore throat.12 The phenomenon of postoperative opioid induced hyperalgesia - changes in intracellular signalling leading to a decrease in the pain threshold - has also been ameliorated by the use of ketamine.9-11 Ketamine may therefore be helpful for attenuating the sore throat that often follows airway instrumentation.

Background

Administration of ketamine has been associated with development of negative dissociative psychological effects such as delirium, hallucinations, and vivid dreaming.9-11 These negative symptoms occur most commonly following anesthetic doses of ketamine - doses capable of producing a state of sedation and anesthesia - and are not as common following administration of lower doses of ketamine intended to produce analgesia.9,10 As noted above, ketamine gargle would be administered as a low dose gargle which would reduce the chances of negative side effects.

Background

Ketamine gargle is a simple intervention that takes less than a minute to administer and can be done with almost all patients, given they have the ability to gargle. The aim of this review is to determine in patients undergoing airway instrumentation whether a ketamine gargle given preoperatively compared to the usual standard of care or placebo reduces postoperative throat soreness within 24 hours It would be assumed that gargling ketamine would provide potent analgesic effects directly to the area that is most affected during airway instrumentation. This, in turn, would lead to a decrease in the incidence of POST.

Background

Minor adverse events, like POST, should not be overlooked by care providers as they have the potential to extend the length of stay of the patient as well as increase the need for added medical intervention that could have been avoided or at least reduced. Benefits of reducing POST include: less postoperative discomfort, less need for pain medications, improved patient satisfaction and a possible decrease in length of stay. Patient satisfaction is subjective and is best summed up as the difference between the experience of care provided and what the patient expected the experience to be.4 Improving patient satisfaction is a crucial component of healthcare delivery because reimbursement for health care services is partly based on how satisfied the patients are with the care they are provided. Different patients each place priority on different things, but all patients can benefit from a simple intervention to reduce discomfort.

Background

The purpose of this review will be to evaluate the effectiveness of ketamine gargle in comparison to placebo in reducing POST.

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