REVIEW
Research Advances in Factors InfluencingSore Throat after
General Anesthesia Tracheal Intubation
Wang Chen¹, Geng Deqin^2
1Yixing Hospital of Traditional Chinese Medicine, Jiangsu,People’s Republic of China
²Xuzhou Medical College Affiliated Hospital, Jiangsu, People’s Republic of China
 
Abstract:Postoperative sore throat (POST) is the most common respiratory complication after general anesthesia tracheal intubation. Comparedto other air pathwayssuch as thelaryngeal mask airway (LMA) or cuffed oropharyngeal airway (COPA), it has the highest incidence rate in tracheal intubation. It is reported that the incidence rate of POST after tracheal intubation is as high as 30–70%. Sore throat adds an uncomfortable feeling to patients and along with postoperative complications would increase the duration of hospital stays. This paper overviewed the factors influencinggeneral anesthesia POST and aims to provide recommendations to increase patient satisfaction.
Keywords: general anaesthesia; tracheal intubation; postoperative sore throat
Citation:Chen W et al. Research Advances in Factors Influencing Sore Throat after
General Anesthesia Tracheal Intubation. J Gen Neuro 2016; 1(1):
*Correspondence to:
Received:            Accepted:           Published Online:
 
 
 
 
 
Definition of POST
Currently, there is not uniform definition of postoperative sore throat (POST). Most researchersbelieve thatPOST is due to the nociceptive pain caused bymucosal injury during general anesthesiatracheal intubation. Clinical manifestations include varying degrees of throat pain, along with hoarseness, low and deep voice, and coughing.Severe cases may affect eating and may even cause fatal injury.
 
Related factors of postoperative sore throat and prevention
Tracheal intubation
Both unskilled tracheal and repeated intubation may cause exacerbation of the laryngopharyngealairway. Knolihet al. have noted that new staff with less than 3 months experience were high-risk factors in sore throat occurrence^[3].Proper consideration of specific circumstances during tracheal intubation should be taken, otherwise tissue damage would occur and these damages may cause bacterial infection. Therefore, intubation techniques should beskillfully mastered, strictly adhering to the rules strictly, intubating when the glottis is fully exposed and the muscles well relaxed –effectively preventing sore throat.
 
Choice of endotracheal tube
A thick diametertubewill not only cause intense stimulation but also tissue damage. Two endotracheal tubes (ETT) of different diameters (6 mm and 7 mm) were comparedto identify which can effectively reduce the incidence of postoperative sore throat. The incidence rate of sore throat by using double-lumen tubeis much higher than using single-lumen tube. The quality of ETT is another factor of laryngopharyngeal damage. In addition, residuals from ETT sterilization could also cause irritation to the throat mucosa. Therefore, a full assessment of the airway and choosing thesuitable ETT should be done appropriately before an intubation.
 
 
 
ETT cuff pressure
In recent years, cuff pressure draws much attention. Most researchersagree that cuff pressure is an important factor indecidingwhether the mucosal airway is injured. It has been proventhat hyperinflatingthe ETTwould cause oppression on the tracheathushavingthe effect ofhemoperfusionof the tracheal mucosa which could lead to tracheal mucosa ischemic necrosis. When the ETT internal pressure exceeds 22mmHg, tracheal mucosal blood flow isdecreased and when it reaches 30mmHg, blood fluid is significantly decreased. When pressure reaches 50mmHg for 15mins, tracheal mucosa ischemia occurs. Presently, most anesthetistswould assess cuff pressure based on personal experiences. Personal experiences only guaranteed54%of patients’ ETT pressureswere within the range of 15–25mmHg. Liu et al.showed that an average ETT pressure of43±33.3mmHg (up to 210 mmHg) can be estimated using the touchballoon method^[12].This has proven that ETT pressure could increase higher than the normal upper limit by using personal experiences. Thus even in brief surgery, routine monitoring of ETT pressure woulddecrease the incidence rate of POST. In laparoscopic surgery, the pneumoperitoneum may cause higher airway pressure and would significantly increase tracheal cuff pressure. Incidence rate of POST will rise, provingthat airway cuff pressure is the main factor of POST.
 
Operation related factors
The incidence rate will be higher in head and neck surgeriesthan in other surgeries. The time of operation is proportional to the occurrence of sore throat. Studies have shown that when tracheal intubation time lasted over 180min, the incidence rate of POST will increase markedly. This may be due tothe prolongedpressure to trachea and ischemia-induceddeterioration. In addition, surgery decubitus is also a factor of POST. Zhang et al.analyzed201 tracheal intubation cases and discovered that decubitus was anaddedincidence rate of sore throat^[15].
 
The patients’ own factors
Biro et al. indicated that the incidence rate of female POST was higher than male patientsand in patients over 60 years of age^[16].Dai et al. also discovered that sore throat incidences in the anesthesia recovery room was higher than in the wards, prompting that environmental psychology might have some influence on the occurrence of sore throat^[17].
 
Tracheal extubation factors
Extubation is the inverse process of tube intubation. When the ETT is r removed, the throat and trachea would be stimulatedcausing laryngeal,tracheal and bronchial spasms, damage, or even vomiting aspiration.Yao et al.experimented onearly extubation under anesthesia to effectively avoid patients choking, coughing, breathlessnessduringETT friction, extrusion and other mechanical damage of the respiratory tract^[19].Results have shown thatearly extubationcould decrease the occurrence of POST. At present, most clinical extubation standardswere conducted when patients are fully conscious and normal muscle tension can take up to 5 seconds, therefore, the agreement of tracheal extubation time has not yet been reached, and it is worth further research.
 
Atomization inhalation and POST
Atomization inhalation is the most common clinical nursing intervention measures toease a sore throat. In recent years, liquid atomizing inhalation has been extensively studied. Research have shownthat atomization liquid formulation consisting of peppermint water, budesonide suspension, or lidocaine mixed with 10mLsaline, 80,000units ofgentamycin and 10mg dexamethasone etc. all have good curative effect. Intravenous dexamethasone injection and budesonide atomizing inhalation 30 minutes before extubation was proven to give better results compared to single intravenous injection of dexamethasone^[24]. Atomizing inhalation administered as soon as patients awakeafter6–8, 10–12 or 24hgeneral anesthesiawas the best time for POST recovery^[25].
Postoperative analgesia and drug use
Along with the development of evidence-based medicine, most POST studies tend to compare new methods (epidural analgesia, PCA and auxiliary non- steroidal drugs) with traditional analgesic methods (usually intravenous use of opioid drugs). Drug analgesia typically has various side effects; therefore, analgesic drugs are chosen withminimalside effects. Lackinga large sample research and a comparative drug study,further research is needed to explore a more scientific method of analgesia.
The application of traditional Chinese acupuncture
More and more clinical evidence have proventhat acupuncturalanalgesia would reduce the dependency on opioids, thereby reducing the side effects of drugs and promotingrecovery. At present, the research about mechanism of acupuncture analgesia has developed from cellular to the molecular level, such as mRNA probe, genetic intervention technology such as gene knockout, acupuncture as well as regulation of the expression of proto-oncogenes, etc. Acupunctural analgesia has some advantages like quick onset, long lasting, no side effects etc. Yang etal. studied the effects of acupuncture “sore throat cavity”treatment on 74 cases of sore throat patients;at the bilateral “choke points” (located at back of the hand, between the third and fourthmetacarpophalangeal joints, closer tothe third joint); after needlepoint oblique disinfection,0.3–0.5 inchesvolar piercing,retaining the needle for 30 minutes^[34]. The results showed that the treatment group’seffective rate was 44.4%, 10.59% better than that of the control group.This clinical evidence suggestedthat acupuncturalanalgesiaprovideda method for analgesia without drugs; it has becomean important component of the modern discipline of pain study.
Outlook
In conclusion, there is a close relationship between the occurrence of POST,tracheal cuffpressure,endotracheal intubation and extubation, the choice of ETT, personal factors, operational factors and so on. Analgesic drugs, aerosol inhalation and acupuncture are effective ways to ease a sore throat, and it played an important role on the improvement of the perioperative clinical outcome in patients with general anesthesia. In consideration of the existence of drug side effects, increasing clinical nursing workload of atomization inhalation, the psychological fear of acupuncture;satisfactory measures to get the most analgesic effect and promotingfunctional recovery neededfuture research.
 
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