Table 1.
Characteristics of eligible trials
| Trials | Country | Groups | Population(n) (Female/Male) | Studydesign | Subjects | Outcomes |
|---|---|---|---|---|---|---|
| Gonzalez 2008 [7] | France | obese(BMI≥30 kg/m2) | 70 | prospective cohort study | GA with endotracheal intubation | Rate of difficult intubation, difficult laryngoscopy and Mallampati score≥3 |
| non-obese(BMI<30 kg/m2) | 61 | |||||
| Mashour 2008 [8] | USA | obese (BMI≥40 kg/m2) | 346 | prospective cohort study | surgery under GA | Rate of difficult intubation and difficult laryngoscopy |
| non-obese (BMI<40 kg/m2) | 4827 | |||||
| Lavi 2009[14] | Israel | obese(BMI≥30 kg/m2) | 105 | prospective cohort study | elective surgery with GA (exclusion emergent surgery) | Rate of Mallampati score≥3 |
| non-obese(BMI<30 kg/m2) | 99 | |||||
| Dargin 2013 [23] | USA | obese (BMI≥30 kg/m2) | 338 | case–control study | intubated in the ICUs, ED, and elsewhere in the hospital(excluded intubations performed in the operating room) | Rate of difficult laryngoscopy and Mallampati score≥3 |
| non-obese(BMI<30 kg/m2) | 715 | |||||
| Juvin 2003 [24] | France | obese(BMI≥35 kg/m2) non-obese(BMI<30 kg/m2) | 129 134 |
prospective cohort study | Obese patients: laparoscopic gastroplasty; non-obese patients: inguinal hernia repair or laparoscopic cholecystectomy | Rate of difficult intubation, difficult laryngoscopy and Mallampati score≥3 |
| Basaranoglu 2010[ 25] | Turkey | obese (BMI>30 kg/m2) | 71 | prospective cohort study | Consecutive women requiring GAfor emergency caesarean section | Rate of difficult laryngoscopy |
| non-obese(BMI≤30 kg/m2) | 168 | |||||
| Ezri 2003 [26] | USA | obese(BMI>35 kg/m2) | 200 | prospective cohort study | obese patients undergoing laparoscopic weight reduction surgery (LapBand); non-obese patients underwent laparoscopic abdominal procedures | Rate of difficult laryngoscopy and Mallampati score≥3 |
| non-obese(BMI≤35 kg/m2) | 1272 | |||||
| Heinrich 2013 [27] | Germany | obese(BMI≥35 kg/m2) | 6334 | case-control study | undergoing general anesthesia for any type of surgical or diagnostic intervention | Rate of difficult laryngoscopy |
| non-obese(BMI<35 kg/m2) | 95556 | |||||
| Lee 2015 [28] | USA | obese(BMI≥30 kg/m2) | 160 | case–control study | adult patients undergoing GA (exclusion emergency intubation) | Rate of difficult laryngoscopy and Mallampati score≥3 |
| non-obese(BMI<30 kg/m2) | 184 | |||||
| Voyagis 1998 [29] | Greece | obese (BMI≥30 kg/m2) | 99 | prospective cohort study | elective surgery under GA with endotracheal intubation( exclusion heart disease, emergency or obstetric surgery) | Rate of difficult laryngoscopy and Mallampati score≥3 |
| non-obese (BMI<40 kg/m2) | 1734 | |||||
| Magalhaes 2013 [30] | Brazil | obese(≥30 kg/m2) | 43 | prospective cohort study | undergoing GA for surgical procedures | Rate of Mallampati score≥3 |
| non-obese(<30 kg/m2) | 45 | |||||
| Turkay Aydogmus 2014 [31] | Turkey | obese(BMI>30 kg/m2) | 20 | prospective cohort study | pregnant women of ASA 1-2 scheduled for GA for cesarian operation | Rate of Mallampati score≥3 |
| non-obese(BMI≤30 kg/m2) | 20 | |||||
| Aslani 2012 [32] | Ireland | obese (BMI>30 kg/m2) | 58 | case control study | women referred to the anaesthetic clinic and relevant historic control groups | Rate of Mallampati score≥3 |
| non-obese(BMI<30 kg/m2) | 34 | |||||
| Combes 2005 [33] | United Kingdom | obese(BMI>35 kg/m2) | 50 | prospective cohort study | patients scheduled to undergo abdominal, orthopedic, or cardiac surgery GA(laryngeal mask) | Rate of Mallampati score≥3 |
| non-obese(BMI<30 kg/m2) | 50 | |||||
| Yildiz 2010 [34] | Italy | obese (BMI>40 kg/m2) | 30 | prospective cohort study | undergoing GA for gynecological surgery with use of the LMA CTrach | Rate of Mallampati score≥3 |
| non-obese (BMI<30 kg/m2) | 30 | |||||
| Lundstrøm 2009 [35] | Denmark | obese(≥35 kg/m2) | 4704 | case control study | all types of surgery (except for cardiothoracic surgery) | Rate of difficult intubation |
| non-obese(<35 kg/m2) | 86617 |
GA general anesthesia, NR not reported, ICU intensive care unit, ED emergency department, ASA American Society of Anesthesiologists, IDS score the intubation difficulty scale score