A comparison of ramping position and sniffing position during endotracheal intubation: a systematic review and meta-analysis / Comparação entre a posição de rampa e posição olfativa durante intubação traqueal: revisão sistemática e meta-análise

Abstract Objectives Positioning during endotracheal intubation (ETI) is critical to ensure its success. We aimed to determine if the ramping position improved laryngeal exposure and first attempt success at intubation when compared to the sniffing position. Methods PubMed, EMBASE, and Cochrane CENTRAL databases were searched systematically from inception until January 2020. Our primary outcomes included laryngeal exposure as measured by Cormack-Lehane Grade 1 or 2 (CLG 1/2), CLG 3 or 4 (CLG 3/4), and first attempt success at intubation. Secondary outcomes were intubation time, use of airway adjuncts, ancillary maneuvers, and complications during ETI. Results Seven studies met our inclusion criteria, of which 4 were RCTs and 3 were cohort studies. The meta-analysis was conducted by pooling the effect estimates for all 4 included RCTs (n = 632). There were no differences found between ramping and sniffing positions for odds of CLG 1/2, CLG 3/4, first attempt success at intubation, intubation time, use of ancillary airway maneuvers, and use of airway adjuncts, with evidence of high heterogeneity across studies. However, the ramping position in surgical patients is associated with increased likelihood of CLG 1/2 (OR = 2.05, 95% CI 1.26 to 3.32, p = 0.004) and lower likelihood of CLG 3/4 (OR = 0.49, 95% CI 0.30 to 0.79, p = 0.004), moderate quality of evidence. Conclusion Our meta-analysis demonstrated that the ramping position may benefit surgical patients undergoing ETI by improving laryngeal exposure. Large scale well designed multicentre RCTs should be carried out to further elucidate the benefits of the ramping position in the surgical and intensive care unit patients.

Resumo Objetivos A posição do paciente durante a Intubação Traqueal (IT) é fundamental para o sucesso do procedimento. Nosso objetivo foi determinar se a posição de rampa melhorou a visualização laríngea e o êxito na primeira tentativa de intubação quando comparada à posição olfativa. Métodos Os bancos de dados PubMed, EMBASE e Cochrane CENTRAL foram pesquisados de forma sistemática a partir da data em que os bancos de dados foram estabelecidos até janeiro de 2020. Nossos desfechos primários incluíram a visualização laríngea avaliada como Cormack‐Lehane Grau 1 ou 2 (CLG 1/2), Cormack‐Lehane Grau 3 ou 4 (CLG 3/4) e o êxito na primeira tentativa de intubação. Os desfechos secundários foram o tempo de intubação, uso de dispositivos adjuvantes para manuseio de vias aéreas, manobras auxiliares e complicações durante a IT. Resultados Sete estudos preencheram nossos critérios de inclusão, dos quais 4 eram Estudos Clínicos Randomizados (ECR) e 3 eram estudos de coorte. A meta‐análise foi conduzida combinando as estimativas de efeito para todos os 4 ECR incluídos (n = 632). Não foram encontradas diferenças entre as posições de rampa e olfativa para razão de chances de CLG 1/2, CLG 3/4, sucesso na primeira tentativa de intubação, tempo de intubação, uso de manobras auxiliares das vias aéreas e uso de dispositivos adjuvantes de vias aéreas, havendo evidência de alta heterogeneidade nos estudos. No entanto, a posição de rampa em pacientes cirúrgicos está associada com maior probabilidade de CLG 1/2 (OR = 2,05; 95% IC 1,26 a 3,32; p = 0,004) e menor probabilidade de CLG 3/4 (OR = 0,49; 95% IC 0,30 a 0,79; p = 0,004), com qualidade moderada de evidência. Conclusão Nossa meta‐análise demonstrou que a posição de rampa pode beneficiar pacientes cirúrgicos submetidos a IT, melhorando a visualização laríngea. ECR multicêntricos bem projetados com amostras grandes devem ser realizados para esclarecer ainda mais os benefícios da posição de rampa nos pacientes cirúrgicos e na unidade de terapia intensiva.

Comparison of the ease of laryngeal mask airway ProSeal insertion and the fiberoptic scoring according to the head position and the presence of a difficult airway / 대한마취과학회지

BACKGROUND: The sniffing position is recommended for conventional laryngeal mask airway (LMA) insertion. However, there has been a high success rate of LMA insertion with the head in the neutral position. The effect of a difficult airway on the ease of LMA insertion is not clear. In this study, we compared the ease of LMA ProSeal(TM) (PLMA) insertion and the fiberoptic scoring according to the head position and the presence of a difficult airway. METHODS: After obtaining informed consent from the subjects, we enrolled 144 adult patients (age range: 18-65) with an ASA physical status 1 or 2. After evaluation of the airway, all the patients were grouped into the EA (easy airway) group (n = 68) and the DA (difficult airway) group (n = 76). According to the head position, each group was divided into the EA-SE (extension) group (n = 35), the EA-SN (sniffing) group (n = 33), the DA-SE group (n = 39) and the DA-SN group (n = 37). The success rate and insertion time at the first attempt were evaluated. The position of the PLMA was fiberoptically scored from the mask aperture of the airway tube in the original head position. After the head position was changed to the sniffing and neutral positions in the SE and SN group, respectively, the position of PLMA was re-evaluated fiberoptically. RESULTS: The success rate and insertion time at the first attempt and the fiberoptic score showed no significant difference among the groups. After head position was changed, there were no significant changes in the fiberopitc scores. CONCLUSIONS: A difficult airway and the head position had no influence on the ease of PLMA insertion and the fiberopic score. Therefore, the head position can be selected according to the individual patient's situation.

The changes of the sternomental distance under general anesthesia and with increasing age

BACKGROUND: Because the sternomental distance (SMD) is evaluated in conscience patients and in the sitting position, this could change under general anesthesia, which is a state that the patient is unconscious and fully relaxed in the supine position. Increasing age also affects the SMD. We investigated the change in the SMD with the patients under general anesthesia and we also investigated the effect of age on the SMD. METHODS: A total of 108 patients were allocated to Group Y (20-30 yr), Group M (31-50 yr) and Group O (51-70 yr). The SMD, as measured when the patients were awake and sitting, was defined as baseline. The SMD was measured in the supine position, the shoulder-suppressed supine position, at the time of loss of consciousness (LOC), 4 min after vecuronium administration and in the sniffing position. The percent change of the SMD (%) was defined as (the baseline SMD - the measured SMD)/the baseline SMD x 100. RESULTS: Compared with the baseline, the SMD decreased significantly in the supine position, the shoulder-suppressed supine position, at the time of LOC, during neuromuscular blockade and in the sniffing position in all the groups. Group O showed a shorter SMD than did Groups Y and M for all the measurements. There was no significant difference in the percent change of the SMD between the groups. CONCLUSIONS: This study demonstrated that the SMD was significantly reduced by the supine position, the sniffing position, at the time of loss of consciousness and during neuromuscular blockade with the patient under general anesthesia and also with the increasing age of the patient.

Randomized Study Comparing the Sniffing Position with the Neutral Position for Lightwand Intubation / 대한마취과학회지

BACKGROUND: The sniffing position is recommended for optimal glottic visualization under direct laryngoscopy. However, there is no study assessing whether sniffing position is superior to a neutral position during lightwand-guided intubation. This prospective, randomized study was performed to compare facilitation of lightwand-guided intubation between the sniffing and neutral positions. METHODS: The study included 180 patients with normal cervical spines requiring tracheal intubation for elective surgery. Patients were randomly allocated into two groups: neutral or sniffing position. Mallampati class, mouth opening distance, thyromental distance, and laryngeal view grade were measured. A lightwand railroaded with an endotracheal tube was bent 90degrees at 5 cm from the distal end for both groups. Time to intubation, success rate and intubation time for the first attempt, hydrodynamic changes, and BIS values were recorded. RESULTS: There were no significant differences in time to intubation, success rate and intubation time of the first trial, hydrodynamic changes, or BIS values between the two positions. CONCLUSIONS: Routine use of the sniffing position does not provide any advantage over the neutral position during lightwand-guided intubation.

Sniffing Position Improves the Laryngeal View Regardless of Body Mass Index / 대한마취과학회지

BACKGROUND: Most anesthesiologists universally recommend the sniffing position and consider it to be essential for improving the performance of orotracheal intubation. However, a recent investigation reported that the sniffing position does not aid the laryngoscope except under specific circumstances (i.e., obesity). Therefore, this study examined the impact of the BMI (body mass index) on the effectiveness of the sniffing position in improving the laryngeal view. METHODS: A video laryngoscopy imaging system and POGO (the percentage of glottic opening) scoring system were used to assess the laryngeal view in 79 adult patients undergoing a laryngoscopy. In each patient, the laryngeal view was videotaped continuously from simple head extension to the sniffing position by inflating a pressure bag as a pillow to obtain approximately 15o of flexion of the lower cervical spine on the chest. The variables assessed included the BMI, the POGO score in each position and the change in the POGO score. RESULTS: The POGO scores improved with the sniffing position (18.1 +/- 14.3%). However, the sniffing position did not improve the POGO score in 16/79 (20.3%) patients. The sniffing position did not worsen the POGO score in any patient. No significant correlation was found between the BMI and the change in the POGO score in the sniffing position (Pearson's correlation coefficient r = 0.075). CONCLUSIONS: The sniffing position has the potential to improve the laryngeal view in all intubations without needing to consider the BMI. Therefore, the sniffing position appears to be advantageous for orotracheal intubation compared with a simple head extension.

The Comparison of Suceess Rates of Lightwand Facilitated Tracheal Intubation in Different Head Positions (Neutral Position versus Sniffing Position) / 대한마취과학회지

BACKGROUND: It has been known that a patient head in sniffing position for lightwand facilitated tracheal intubation is not an anatomically appropriate method. However, there is no evidence nor study whether it is true or not. In this study, we compared success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position. METHODS: With informed consent, sixty adult patients of ASA physical status I or II were randomly allocated into two groups: neutral position (N) or sniffing position (S) group. A lightwand and tube were bent at approximately a 90degrees degree angle for N group and a 60 degree angle for S group on the basis of mouth axis and pharyngeal axis. The time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications during the procedure were recorded. RESULTS: There was no significant difference in the time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications between neutral position and sniffing position groups. CONCLUSIONS: Success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position showed no significant difference. Therefore, both positions are suitable for lightwand assisted intubation.

The Comparison of Suceess Rates of Lightwand Facilitated Tracheal Intubation in Different Head Positions (Neutral Position versus Sniffing Position) / 대한마취과학회지

BACKGROUND: It has been known that a patient head in sniffing position for lightwand facilitated tracheal intubation is not an anatomically appropriate method. However, there is no evidence nor study whether it is true or not. In this study, we compared success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position. METHODS: With informed consent, sixty adult patients of ASA physical status I or II were randomly allocated into two groups: neutral position (N) or sniffing position (S) group. A lightwand and tube were bent at approximately a 90degrees degree angle for N group and a 60 degree angle for S group on the basis of mouth axis and pharyngeal axis. The time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications during the procedure were recorded. RESULTS: There was no significant difference in the time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications between neutral position and sniffing position groups. CONCLUSIONS: Success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position showed no significant difference. Therefore, both positions are suitable for lightwand assisted intubation.