In this study, 13% of adult patients (40 out of 300) had at least one or more respiratory complications with deep extubation. This is in line with a previous publication by Kim and colleagues in which one group that received desflurane had a 48% complications rate (12 out of 25 patient) while the other group that received desflurane with remifentanil had a 3.4% complication rate (1 out of 29 patients) . It is also consistent with Fan et al’s report, where percentage of patient with airway complications ranges from 12–37.5% . An important difference between ours and prior studies is how respiratory complications are defined. For example, whereas Kim et al’s defined complications as coughing and breath holding, we expanded the criteria to capture additional complications, including significant desaturation, laryngospasm, stridor, bronchospasm and reintubation, that could also influence the success of deep extubation. It is worth noting that all of these complications were easily corrected by the anesthesia providers in our study with no need for drastic interventions such as reintubation. However, our data also showed that patients who had complications with deep extubation tended to stay longer in the OR compared with patients who did not.
It is well understood that deep extubation can minimize adverse hemodynamic reflexes in appropriate situations . Nonetheless, many anesthesiologists are reluctant to perform deep extubation in adults because of concerns for potential respiratory complications . The present study indicates that deep extubations in adults is likely safer than in the pediatric population. Our airway complication rate of 13% in adult patients is significantly lower than the 40% complication rate (64 out of 159 patients) reported in a recent meta-analysis of pediatric patients . While it is possible that patient selection and provider difference account for the lower rate; it is also feasible that the pediatric airway is more irritable and sensitive to stimulation than the adult airway .
Present study suggests that patient selection plays an integral part in the success of endotracheal deep extubations. Our anesthesia providers were free to choose their patients for deep extubations. Overwhelmingly, the patients selected had easy airway placement based on the Cormack and Lehane’s Grade as only 1 patient out of 300 had a grade 4 view, which is a probable factor contributing to the overall low complications rate. On the flip side, our data also shows that when the provider chose to deep extubate patient with lower O2 saturation levels 5 min prior to extubation, these patients are more likely to have significant airway complications. Our results suggest that higher BMI patients are less likely to tolerate deep extubations. We observed a statistically significant correlation between higher BMI and likelihood of complications during deep extubation. The median BMI in the complications group was 30 while the median BMI in the no complications group was 26. Obesity has been shown to worsen oxygenation through several mechanisms, including increased intraabdominal pressure and atelectasis [16–18]. Whether an isolated elevated BMI is a causal factor for complications during deep extubations will need further investigation.
The depth of anesthesia suitable for a smooth deep extubation is primarily based on the MAC of inhaled anesthetics. Previous studies suggested that extubation could be performed at an inhaled anesthetic level as low as 1 MAC [4, 12, 19–21]. Some of the differences in MAC levels were likely due to variations in adjuvant opioid use, because opioid medications have been shown to minimize coughing and various extubation related adverse events [22, 23]. Here, we allowed the providers to freely decide the type and amount of opioid use appropriate for practice and did not observe a significant difference in the amount of opioid used in the complications versus no complications groups.
There were several limitations to this study. Firstly, this is a single-center prospective study, and the anesthesiologists were not and could not be blinded to the treatment technique. Secondly, there is also significant selection bias in the study, as no patients with history of difficult airway underwent deep extubation. Thirdly, other than the deep extubation technique, the anesthetic management was not standardized. However, this is a reality of every day anesthesia practice, irrespective of the extubation technique. Lastly, an experienced anesthesia provider remained with each patient until an adequate control of the airway was achieved, which could have contributed to the low incidence rate of complications. Moving forward, we hope our data can facilitate a more informed calculation of sample size for future studies comparing the complication rate of deep versus awake extubation in adults. As expected, time to leaving the OR was higher in the complication group, however, the general question about differences in operating room turnover times between deep and traditional extubation techniques has not been properly answered. Finally, there are probably many different ways of performing a deep extubation and further studies should be done to fine tune this technique.