Arathi B H^1*, Sangeetha²

 

¹Associate Professor, ²Junior Consultant, Kidwai Memorial Institute of oncology, M.H. Marigowda Road (near dairy circle) Bangalore 560029, Karnataka, INDIA.

Email: arathibh@gmail.com

 

Figure­­ 1: Age distribution of patients studied

The age of the patients in both the groups are comparable and the difference in mean age between the groups is not statistically significant

Figure 2: Gender distribution of patients studied

The gender distribution of the patients in both the groups are comparable.

 

Figure 3: weight distribution of patients studied

The mean weight in control group is 54.10 kgs and in study group is 56.55 kgs. Statistically insignificant difference.

 

Table 1: Mean duration of surgery in two groups of patients studied

Figure 4: Mean duration of surgery in two groups of patients studied          Figure 5: Comparison of HR (beats/min) in two groups of patients

studied

Figure 4, The mean duration of surgeries, patients underwent in both the groups is statistically comparable.

Figure 5, Basal heart rate was comparable in both groups. But it was statistically and clinically lower in study group from 5^th minute of drug infusion till the end of infusion; at reversal administration; extubation and post extubation 5, 10, 15, 20, 25 and 30 minutes compared to basal value. Though the above table shows statistically significant lower values at 60 and 90 minutes post extubation, they were not clinically significant.

 

 

Figure 6                                                                                                         Figure 7

Figure 6: Comparison of systolic blood pressure (in mm of Hg) in two groups of patients studied; Figure 7: Comparison of diastolic blood pressure (in mm of Hg) in two groups of patients studied

Figure 6, Both the groups were comparable with respect to basal SBP values. SBP values were statistically and clinically significantly lower in Group D at 10th minute of study drug infusion; at reversal administration; extubation and post extubation 5, 10, 15 and 20 minutes compared to basal values. SBP values in group C returned to basal levels gradually over next hour.

Figure 7, Basal DBP values in both the groups were comparable. DBP values were statistically and clinically significantly lower in study group at 10th minute of dexmedetomidine infusion; at the time of reversal administration; extubation and post extubation 5, 10, 15, 20, 25 and 30 minutes compared to baseline values. DBP values at 45, 60, 75 and 90 minutes post extubation though statistically significant were not clinically significant

Figure 8: Comparison of mean arterial pressure (in mm of Hg) in two groups of patients studied

MAP values in both the groups were comparable at baseline. Values were statistically and clinically significantly lower in Group D compared to basal value during the period of drug infusion; at reversal; extubation and post extubation 5, 10, 15, 20, 25 and 30 minutes. MAP values post extubation 45, 60, 75 and 90 minutes were clinically not significant though statistically significant.

 

Table 2: Comparison of Ramsay Sedation Scale in two groups of patients studied

Patients in dexmedetomidine group were significantly sedated compared to control group at extubation and post extubation 5, 10, 15 and 30 minutes.

 

Table 3: Extubation quality 5- point scale (cough score) in two groups of patients studied

number of bouts of cough per patient was significantly lower in Group D when compared to Group C. Extubation quality 5- point scale was lower in study group implying smoother extubation as compared to control group.

 

Table 4: Comparison of Mean time to eye opening in two groups of patients studied

Time to eye opening was statistically and clinically significantly prolonged in Group D compared to Group C with P<0.001.

 

Table 5: Comparison of Mean time to extubation in two groups of patients studied

Time to extubation was statistically and clinically significantly prolonged in Group D compared to Group C with P<0.001.

 

Table 6: Comparison of complications in two groups of patients studied

10 patients in study group had hypotension which was statistically significant. This responded to intravenous fluids administration. 9 patients in dexmedetomidine group had bradycardia, but this was transient and responded to injection atropine. Laryngospasm and desaturation (SpO2< 93%) was not observed in either of the groups.

 

DISCUSSION

Emergence from general anaesthesia and tracheal extubation is often accompanied with tachycardia and hypertension. Hartley M and Vaughan RS¹ found that there is an increase of 20% in heart rate and systolic blood pressure during extubation and cause was attributed to increase plasma concentration of adrenaline. These responses may produce myocardial ischemia or infarction in susceptible patients. Alpha2 -agonists decrease the sympathetic outflow and noradrenergic activity, thereby counteracting hemodynamic fluctuations occurring at the time of extubation due to increased sympathetic stimulation.³² This study was designed to assess prospectively the degree of attenuation of hemodynamic responses and airway reflexes to extubation by administration of dexmedetomidine at the dosage of 0.5 µg/ kg body weight.. In our study both the groups were comparable with respect to age, sex, weight, ASA physical status grading and duration of surgery.

HEMODYNAMIC PARAMETERS

In our study we observed that HR did not show a significant rise compared to basal value from 2^nd minute of drug administration, during reversal, at extubation and any period post extubation. But in control group, there was a significant rise in HR compared to basal value. The rise in HR in control group was more persistent than study group. This observation is in concurrence with the study done by Jain D et al..³² where the pulse rate in study group remained below the (baseline value) at all time intervals following extubation. Bradycardia was observed in __ 25%of patients in study group which responded to injection atropine. This is in conjunction with the observation by Aksu R et al.³³ SBP, DBP and MAP values were significantly lower in study group compared to baseline values at all times from the time of dexmedetomidine infusion to post extubation 30 minutes. This is in conjunction with the study conducted by Jain D et al..³² in which study group patients received 1 µg/ kg of dexmedetomidine and they did not observe any significant change (p<0.05) in the blood pressure in dexmedetomidine group throughout the study period. On the contrary, systolic blood pressure rose significantly (p<0.05) in control group following extubation as observed in our study which we achieved with 0.5 µg/ kg of dexmedetomidine. In our study none of the patients in study group had hypertension against control group. This observation is in contradiction with the study done by Aksu R et al..³³ who observed significantly increased SBP at 1 and 5 minutes after extubation. Probably this is due to infusion of dexmedetomidine over 5 minutes rather than slow infusion.

 

RESPIRATORY PARAMETERS

Dexmedetomidine by virtue of its analgesic and sedative properties is known to blunt airway reflexes. Exutubation response was smooth extubation against patients in control group. Incidence of coughing was significantly higher in control group than when compared to study group .This is in accordance with study done by Aksu R et al.³³ Guler G et al..³⁶ they also noted the effect of dexmedetomidine on children undergoing adenotonsillectomy wherein dexmedetomidine group had significantly decreased incidence and severity of agitation and a smooth extubation without any increase in incidence of side effects. Also, the number of severe coughs per patient was significantly decreased in study drug group when compared with control group. This further supports our observation. Hence, dexmedetomidine improves extubation quality.

SpO2 values were comparable in both the groups with no incidence of desaturation. Also, no bronchospasm or laryngospasm was observed in either of the groups. These observations are in concurrence with study conducted by Aksu R et al.³³

 

COMPLICATIONS

Sedation in our study was assessed using Ramsay Sedation Scale. Significant number of patients in study group were drowsy but responded to oral commands (score of 3) following extubation as against patients in control group who were co-operative and oriented (score of 2). However, those patients who were drowsy maintained SpO2with humidified oxygen administered by facemask at 4 liter/ minute which was routinely provided for all patients in PACU. This observation is in agreement with the comparative study done between dexmedetomidine and fentanyl in those undergoing rhinoplasty by Aksu R et al.³³ But, in contrast to Jain D et al..³² who did not notice sedation in both the groups probably because of the difference in the anaesthetic technique employed by the authors.

Sedation score was significant post extubation for __ minutes in study group compared with control group. After this period sedation scores were comparable in both the groups.

EXTUBATION PARAMETERS

Guler G, Akin A et al..³⁶ in their study on emergence agitation in children undergoing adenotonsillectomy observed that time to extubation and emergence were prolonged significantly when compared to control group with p<0.05. (5.03± 2.3 vs 3.30±1.3minutes and 9.30± 2.9 vs 7.20± 2.7 minutes, respectively). This observation is in agreement with our study conducted wherein time to extubation and eye opening (i.e, interval between cut off of nitrous oxide to extubation and eye opening respectively) were significantly prolonged in dexmedetomidine group when compared to control group.

 

CONCLUSION

In conclusion, our study demonstrates that single- dose of dexmedetomidine 0.5 µg/ kg body weight administered over 10 minutes, before tracheal extubation attenuates the airway and hemodynamic reflexes during emergence from anaesthesia providing smooth extubation without causing undue sedation. But may delay time to extubation and eye opening.

 

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