obstructive sleep apnea syndrome ( osas ) is a highly prevalent disorder affecting about 4% of adults , and is associated with repetitive episodes of transient oxygen desaturation during sleep .
osas is an independent risk factor for a number of cardiovascular diseases [ 24 ] .
although uppp expands pharyngeal cavity and improves upper respiratory tract obstruction , it is often complicated by edema , strictures , bleeding , increased hypopharyngeal secretions , and decreased pharyngeal airway - protective reflexes .
therefore , patients are prone to have airway re - obstruction and apnea during recovery from anesthesia .
adequate sedation is important in the post - anesthesia care unit ( pacu ) following uppp to ensure patient comfort and decrease the duration of mechanical ventilation ( mv ) , pacu stay , and bleeding .
the anesthetic propofol is commonly used in the icu for sedation of the ventilated postsurgical patient .
however , propofol sedation may also cause respiratory depression , which may be accentuated by the concurrent use of opioids .
dexmedetomidine is a highly specific alpha-2-adrenergic receptor agonist that possesses sedative , anxiolytic , and analgesic effects . at clinically effective doses , continuous sedation with intravenous dexmedetomidine
does not interfere with the normal course of ventilator weaning and extubation because it does not depress respiratory drive or decrease arterial oxygen saturation .
the aim of this study was to retrospectively compare the effects of dexmedetomidine versus propofol as sedatives following uppp in the pacu .
after approval of the ethics committee of the general hospital of shenyang military region ( china ) , a total of 150 patients undergoing uppp and recovering from general anesthesia were studied .
all subjects were diagnosed with osas based on symptoms such as heavy and loud snoring , witnessed apneas , and/or daytime sleepiness and choking during sleep .
each subject underwent clinical assessment , testing for complete blood count , liver and kidney function , and cardiac enzymes .
the patients were considered ineligible if they had unstable angina or acute myocardial infarction in the last 30 days , uncontrolled diabetes , morbid obesity ( bmi > 40 ) , ejection fraction below 30% , or were treated with neuromuscular blocking agents .
patients were also excluded if they had a history of alcohol or drug abuse or their neurologic condition was difficult to evaluate .
patients in the propofol group ( n=61 ) received an infusion of propofol ( 3 mg / kg / hr ) , which was titrated up to a maximum of 6 mg / kg / h until they were adequately sedated ( ramsay sedation score 4 ) .
patients in the dexmedetomidine group ( n=63 ) received 1.0 g / kg of dexmedetomidine over a 10-min period and then 0.5 to 1.0 g / kg / h infusion to maintain a ramsay sedation score 4 .
if a dexmedetomidine - sedated patient could not be maintained within the desired sedation range and the infusion rate was already at the recommended maximum of 1.0 g / kg / h , the patient received intravenous injection of propofol ( 3 mg / kg / hr ) until ramsay sedation score was at least 4 .
tramadol ( 1 mg / kg ) was allowed for pain relief in both groups .
staff determined the need for tramadol depending upon the signs of pain [ e.g. , sweating , increased blood pressure , and elevated heart rate ( hr ) ] before extubation or when the score was no more than 2 on the bruggemann comfort scale ( bcs ) assessed 10 min after extubation by direct communication with the patient .
intraoperative anesthetics , narcotics , and other medications were standardized by the department of anesthesiology by induction with propofol 2 mg / kg in combination with midazolam 2 mg , sufentanil 0.5 g / kg , and rocuronium bromide 0.8 mg / kg .
anesthesia was maintained with propofol ( 38 mg / kg / h ) and remifentanil ( 315 g / kg / h ) administered with an infusion pump , and 0.52.5% sevoflurane administered by vaporization .
blood pressure and heart rate ( hr ) were maintained within 20% of awake values .
propofol , remifentanil , and sevoflurane were stopped when the patients were transferred to the pacu after the operation . in the pacu ,
mechanical ventilation was stopped when end - tidal ( et ) anaesthetic concentration dropped to 0.2% .
respiration was then manually assisted until recovery of spontaneous breathing ( tidal volume > 6 ml / kg ) . each patient
was given 5 l / min of oxygen via oxygen insufflation after recovery of adequate spontaneous ventilation , followed by 2 l / min oxygen through a nasal cannula after extubation .
a patient was considered ready for extubation if awake or arousable , cooperative and comfortable , and if fraction of inspiration o2 ( fio2 ) was less than 0.4 and blood oxygen saturation ( spo2 ) exceeded 96% .
in addition , the partial pressure of o2 in arterial blood ( pao2 ) should be over 80 mmhg , partial pressure of carbon dioxide in the blood ( paco2 ) below 50 mmhg , tidal volume greater than 6 ml / kg , spontaneous respiratory rate lower than 25/min , with steady circulatory function and no hemorrhagic secretions observed in the upper respiratory tract .
patients with a modified aldrete score between 9 and 10 were transferred to the ward .
the electrocardiogram , hr , noninvasive systolic and diastolic arterial blood pressures , spo2 , respiratory rate , bis ( bis xp 3.4 monitor , aspect medical systems , newton , ma ) were recorded preoperatively ( t0 ) , when sedation was initiated ( t1 ) , and at the following timepoints : 30 min after dexmedetomidine or propofol initiation ( t2 ) , extubation ( t3 ) , 10 min after extubation ( t4 ) , and at discharge from the pacu ( t5 ) .
time to extubation : defined as the time interval between stopping dexmedetomidine or propofol and the fulfillment of extubation criteria .
ramsay sedation scores   were assessed at t2 and rass agitation scores ( rass )   were assessed at t3 . at t3 ,
if rass score was at least 3 points , the patients were treated with analgesics ( tramadol ) and sedatives ( dexmedetomidine or / and propofol with an infusion pump ) .
if rass score was at least 3 , the sedation was continued as before until rass score was 2 or less .
if rass score was 2 or less , sedatives were discontinued and the patients regained consciousness gradually .
cough responses during extubation were scored as 1=no incidence of cough ; 2=smooth extubation , slight coughing ( 1~2 coughs ) ; 3=moderate coughing ( 3~4 coughs ) ; 4=severe or repetitive coughing ( 5~10 coughs ) ; 5=patient discomfort , poor extubation ( > 10 severe coughs ) .
bcs : 0=continuous pain ; 1=no pain without movement , but serious pain when breathing deeply or coughing ; 2=no pain without movement , but mild pain when breathing deeply or coughing ; 3=no pain , even when breathing deeply ; and 4=no pain when coughing ) .
potential adverse drug reactions were noted during pacu : bradycardia ( hr < 50 bpm ) , tachycardia ( hr > 100 bpm ) , hypotension [ mean arterial pressure ( map ) was less than 30% of the baseline ] , hypertension ( map was more than 30% of the baseline ) , respiratory depression ( respiratory rate 8 bpm or spo2 90% for a duration exceeding 5 min ) , glossoptosis , nausea or vomiting , rigors , and bleeding . statistical analysis was performed using a commercial software package ( spss 17.0 , chicago , il ) .
this sample size for the study was based on tramadol consumption in the pacu after uppp surgery , assuming a requirement of rescue tramadol 0.72 ( sd0.23 ) mg / kg with dexmedetomidine - ketamine - based anesthesia . to detect a 30% reduction in tramadol requirements in the pacu after surgery
, 60 subjects per treatment group would be needed for a study with an alpha level of 0.05 and a beta level of 0.2 ( 80% power ) .
continuous variables with a normal distribution are reported as mean ( standard deviation , sd ) .
differences in the incidence of adverse events were analyzed by chi - square test . a p - value less than 0.05 was considered statistically significant .
after approval of the ethics committee of the general hospital of shenyang military region ( china ) , a total of 150 patients undergoing uppp and recovering from general anesthesia were studied .
all subjects were diagnosed with osas based on symptoms such as heavy and loud snoring , witnessed apneas , and/or daytime sleepiness and choking during sleep .
each subject underwent clinical assessment , testing for complete blood count , liver and kidney function , and cardiac enzymes .
the patients were considered ineligible if they had unstable angina or acute myocardial infarction in the last 30 days , uncontrolled diabetes , morbid obesity ( bmi > 40 ) , ejection fraction below 30% , or were treated with neuromuscular blocking agents .
patients were also excluded if they had a history of alcohol or drug abuse or their neurologic condition was difficult to evaluate .
patients in the propofol group ( n=61 ) received an infusion of propofol ( 3 mg / kg / hr ) , which was titrated up to a maximum of 6 mg / kg / h until they were adequately sedated ( ramsay sedation score 4 ) .
patients in the dexmedetomidine group ( n=63 ) received 1.0 g / kg of dexmedetomidine over a 10-min period and then 0.5 to 1.0 g / kg / h infusion to maintain a ramsay sedation score 4 .
if a dexmedetomidine - sedated patient could not be maintained within the desired sedation range and the infusion rate was already at the recommended maximum of 1.0 g / kg / h , the patient received intravenous injection of propofol ( 3 mg / kg / hr ) until ramsay sedation score was at least 4 .
tramadol ( 1 mg / kg ) was allowed for pain relief in both groups .
staff determined the need for tramadol depending upon the signs of pain [ e.g. , sweating , increased blood pressure , and elevated heart rate ( hr ) ] before extubation or when the score was no more than 2 on the bruggemann comfort scale ( bcs ) assessed 10 min after extubation by direct communication with the patient .
intraoperative anesthetics , narcotics , and other medications were standardized by the department of anesthesiology by induction with propofol 2 mg / kg in combination with midazolam 2 mg , sufentanil 0.5 g / kg , and rocuronium bromide 0.8 mg / kg .
anesthesia was maintained with propofol ( 38 mg / kg / h ) and remifentanil ( 315 g / kg / h ) administered with an infusion pump , and 0.52.5% sevoflurane administered by vaporization .
blood pressure and heart rate ( hr ) were maintained within 20% of awake values .
propofol , remifentanil , and sevoflurane were stopped when the patients were transferred to the pacu after the operation . in the pacu ,
mechanical ventilation was stopped when end - tidal ( et ) anaesthetic concentration dropped to 0.2% .
respiration was then manually assisted until recovery of spontaneous breathing ( tidal volume > 6 ml / kg ) . each patient
was given 5 l / min of oxygen via oxygen insufflation after recovery of adequate spontaneous ventilation , followed by 2 l / min oxygen through a nasal cannula after extubation .
a patient was considered ready for extubation if awake or arousable , cooperative and comfortable , and if fraction of inspiration o2 ( fio2 ) was less than 0.4 and blood oxygen saturation ( spo2 ) exceeded 96% .
in addition , the partial pressure of o2 in arterial blood ( pao2 ) should be over 80 mmhg , partial pressure of carbon dioxide in the blood ( paco2 ) below 50 mmhg , tidal volume greater than 6 ml / kg , spontaneous respiratory rate lower than 25/min , with steady circulatory function and no hemorrhagic secretions observed in the upper respiratory tract .
patients with a modified aldrete score between 9 and 10 were transferred to the ward .
the electrocardiogram , hr , noninvasive systolic and diastolic arterial blood pressures , spo2 , respiratory rate , bis ( bis xp 3.4 monitor , aspect medical systems , newton , ma ) were recorded preoperatively ( t0 ) , when sedation was initiated ( t1 ) , and at the following timepoints : 30 min after dexmedetomidine or propofol initiation ( t2 ) , extubation ( t3 ) , 10 min after extubation ( t4 ) , and at discharge from the pacu ( t5 ) .
time to extubation : defined as the time interval between stopping dexmedetomidine or propofol and the fulfillment of extubation criteria .
ramsay sedation scores   were assessed at t2 and rass agitation scores ( rass )   were assessed at t3 . at t3 ,
if rass score was at least 3 points , the patients were treated with analgesics ( tramadol ) and sedatives ( dexmedetomidine or / and propofol with an infusion pump ) .
if rass score was at least 3 , the sedation was continued as before until rass score was 2 or less .
if rass score was 2 or less , sedatives were discontinued and the patients regained consciousness gradually .
cough responses during extubation were scored as 1=no incidence of cough ; 2=smooth extubation , slight coughing ( 1~2 coughs ) ; 3=moderate coughing ( 3~4 coughs ) ; 4=severe or repetitive coughing ( 5~10 coughs ) ; 5=patient discomfort , poor extubation ( > 10 severe coughs ) .
bcs : 0=continuous pain ; 1=no pain without movement , but serious pain when breathing deeply or coughing ; 2=no pain without movement , but mild pain when breathing deeply or coughing ; 3=no pain , even when breathing deeply ; and 4=no pain when coughing ) .
potential adverse drug reactions were noted during pacu : bradycardia ( hr < 50 bpm ) , tachycardia ( hr > 100 bpm ) , hypotension [ mean arterial pressure ( map ) was less than 30% of the baseline ] , hypertension ( map was more than 30% of the baseline ) , respiratory depression ( respiratory rate 8 bpm or spo2 90% for a duration exceeding 5 min ) , glossoptosis , nausea or vomiting , rigors , and bleeding .
statistical analysis was performed using a commercial software package ( spss 17.0 , chicago , il ) .
this sample size for the study was based on tramadol consumption in the pacu after uppp surgery , assuming a requirement of rescue tramadol 0.72 ( sd0.23 ) mg / kg with dexmedetomidine - ketamine - based anesthesia . to detect a 30% reduction in tramadol requirements in the pacu after surgery
, 60 subjects per treatment group would be needed for a study with an alpha level of 0.05 and a beta level of 0.2 ( 80% power ) .
continuous variables with a normal distribution are reported as mean ( standard deviation , sd ) .
differences in the incidence of adverse events were analyzed by chi - square test . a p - value less than 0.05 was considered statistically significant .
sixty - one patients in the propofol group and 63 patients in the dexmedetomidine group were analyzed ( figure 1 ) .
the 2 groups were similar in age , bmi , apnea - hypopnea index ( ahi ) , neck size , and ess score .
there were no significant differences in anesthesia time and operative time between the 2 groups .
figure 2 shows the hr , noninvasive systolic and diastolic arterial blood pressures , spo2 , etco2 , and bis at each point of time . in the propofol group ,
hr , systolic blood pressure ( sbp ) , and diastolic blood pressure ( dbp ) significantly increased at the time of extubation ( t3 ) in contrast to dexmedetomidine - sedated patients who manifested non - significant changes in sbp and dbp ( p>0.05 ) .
dexmedetomidine sedation decreased the hr significantly after its initiation and was significantly less than in the propofol group .
the spo2 and etco2 were not changed in the dexmedetomidine group ( both p<0.05 , in comparison with the propofol group ) .
bis values were significantly lower in the dexmedetomidine group than in the propofol group at ramsay sedation scores of 4 and 5 ( p=0.045 ) .
there were no significant differences in ramsay sedation scores between groups during assisted ventilation ( t2 ) ( p=0.259 ) .
after extubation , bcs and rass in the dexmedetomidine group were lower than in the propofol group ( p=0.024 and 0.042 , respectively ) . during
assisted ventilation , the dexmedetomidine - sedated patients required less tramadol than patients in the propofol group ( p=0.001 ) ( table 2 ) .
coughing during extubation occurred more frequently and was more severe in the propofol group compared to the dexmedetomidine group ( p<0.001 ) ( table 3 ) .
the time to spontaneous breathing in the dexmedetomidine group was significantly shorter than in the propofol group ( p=0.035 ) .
patients fulfilled the criteria of extubation earlier in the dexmedetomidine group ( p=0.028 ) ( table 4 ) .
there were fewer dexmedetomidine - sedated patients requiring treatment for emergent adverse reactions than in the propofol group ( p=0.002 ) .
there were no differences between the 2 groups in the length of stay in the pacu .
four categories  hypertension , tachycardia , bradycardia and respiratory depression  were significantly different between groups .
hypertension , tachycardia and respiratory depression occurred significantly more frequently in the propofol group ( p=0.038 and 0.027 , respectively , table 5 ) .
dexmedetomidine , a a2-adrenoreceptor agonist well known for its anti - anxiety , sedative , analgesic , anaesthetic - sparing and respiratory - sparing effects , is also a perfect candidate for premedication . in the pacu of our department , we administrated dexmedetomidine to patients after uppp for sedation . in our study ,
analgesic consumption , pain intensities , sedation and agitation scores , cardiovascular and respiratory variables , and adverse reactions such as nausea , vomiting , and rigors were compared for 4 hours after operation .
the results show that dexmedetomidine - based sedation was safe and effective for postsurgical uppp patients .
our results also showed that at comparable ramsay scores , bis values were lower with dexmedetomidine sedation than with propofol .
patients who receive dexmedetomidine are quite comfortable and are still arousable and responsive to stimuli .
evaluated the intraoperative sedative effects of dexmedetomidine and propofol , and demonstrated that although sedation with dexmedetomidine was achieved slowly , similar effects were found between groups 25 min after initiation of infusion .
pain was the main cause of agitation in patients recovering from uppp , reflected by frequent complaints of throat pain and discomfort after extubation .
a previous study showed that visual analogue scale ( vas ) was 4~6 points in a quiet condition after uppp .
prompt and effective management of pain is one of the most effective measures to prevent and treat postoperative complications following uppp .
opioid analgesics are commonly used to manage postoperative pain , but in large doses they may cause respiratory depression . in our study , dexmedetomidine - sedated patients required significantly less tramadol and
this analgesic - sparing effect of dexmedetomidine is well documented in previous studies [ 2426 ] .
we compared the uppp patients receiving dexmedetomidine or propofol during recovery from extubation in the pacu . under similar levels of sedation ,
dexmedetomidine efficiently inhibited the stress response around tracheal extubation , whereas propofol increased blood pressure and hr .
dexmedetomidine initiation was associated with decreased hr and transient hypertension , which is consistent with other reports in the literature .
the effect of dexmedetomidine in reducing the incidence and severity of cough during extubation is consistent with the study of aksu et al . , in which injection of 0.5 g / kg dexmedetomidine before extubation effectively alleviated the airway responses and suppressed the cough response and hemodynamic fluctuations .
dexmedetomidine also prevented the occurrence of nausea , vomiting , and chills after extubation . in this study , the incidence of nausea , vomiting and chills was less in patients receiving dexmedetomidine .
none of the 124 patients in this study had glossoptosis , and the influence of dexmedetomidine and propofol on glossoptosis was similar .
the time to extubation and the time to recovery of spontaneous breathing were significantly shorter in the dexmedetomidine group compared with the propofol group .
patients in the dexmedetomidine group were easy to wake and recovered consciousness more quickly and completely .
these results suggest that the extubation quality was better in the dexmedetomidine group than in the propofol group .
respiratory depression during the uppp recovery period is commonly caused by the residual effects of anesthetics such as opioids .
assisted ventilation or ventilation control should be performed until the recovery of spontaneous breathing , and antagonist must be used with caution to prevent agitation .
reported that dexmedetomidine did not significantly prolong the recovery time of spontaneous breathing and the eye - opening time compared with propofol . indeed , several other studies with dexmedetomidine support observations that dexmedetomidine used at clinical doses did not depress respiratory drive [ 3335 ] .
however , some patients may have respiratory depression due to the interaction between dexmedetomidine and residual anesthetics and muscle relaxants .
reported that geriatric patients presented with respiratory depression 90 min after extubation following infusion of 0.26 g / kg / h dexmedetomidine for 3.5 h , indicating that higher doses or prolonged administration of dexmedetomidine caused respiratory depression . in this study , respiratory depression occurred in 12 cases after drug withdrawal and before extubation in the propofol group , and in 4 cases after extubation in the dexmedetomidine group .
these data suggest that inappropriate application of dexmedetomidine in patients of different ages resulted in respiratory depression .
agitation scales were monitored occasionally by an assessor who rated the level of agitation on the basis of a single observation and interaction with the patient .
discrete observations may fail to account for changes in sedation level that may occur between assessments .
plasma drug concentrations were not measured , and therefore , can not be assumed to have remained constant or similar in patients .
this drug can induce suitable depth of sedation and the analgesic effect , significantly reduce the use of analgesics without clinically significant respiratory depression and agitation during extubation , and shorten the time to extubation .
 backgroundadequate sedation is important in the post - anesthesia care unit ( pacu ) following uvulopalatopharyngoplasty ( uppp ) to ensure patient comfort and decrease the duration of mechanical ventilation ( mv ) , pacu stay , and bleeding . 
 this study aimed to compare dexmedetomidine and propofol as sedatives after uppp in the pacu.material/methodswe randomized 124 mechanically ventilated adults following uppp who were managed in the pacu of the general hospital of the shenyang military region between january 2014 and june 2014 , to receive either dexmedetomidine or propofol . 
 the patients in the propofol group received an infusion of propofol ( 3 mg / kg / h ) titrated up to 6 mg / kg / h to attain a ramsay sedation score 4 . 
 the dexmedetomidine group patients received 1.0 g / kg of dexmedetomidine over a period of 10 minutes and then 0.5 to 1.0 g / kg / h infusion to maintain a ramsay sedation score 4.resultsbispectral index ( bis ) values were significantly lower in the dexmedetomidine group than in the propofol group at ramsay sedation scores of 4 and 5 . 
 the mean times to spontaneous breathing , waking , and extubation were shorter in the dexmedetomidine group . 
 tramadol requirement was significantly reduced in the dexmedetomidine group ( p<0.05 ) . 
 incidence of cough during the extubation process in the propofol group was higher than in the dexmedetomidine group . 
 after extubation , bruggemann comfort scale ( bcs ) and rass agitation scores ( rass ) were decreased in the dexmedetomidine - sedated patients.conclusionsdexmedetomidine provides safe and effective sedation for post - uppp surgical patients and significantly reduces the use of analgesics , with minimal adverse effects . 
Background
Material and Methods
Subjects
Study design
Statistical analysis
Results
Discussion
Conclusions