Study reference

Study characteristics

Patient characteristics ²

Intervention (I)

Comparison / control (C) ³

Follow-up

Outcome measures and effect size ⁴

Comments

Ibraheim, 2008

Type of study: RCT

Setting and country: King Khalid University Hospital, Saudi Arabia

Funding and conflicts of interest: Not reported.

Inclusion criteria:

After institutional Review Board approval, thirty morbidly obese (BMI >35 kg/m2), ASA I & II patients to undergo gastric banding  procedures, were studied.

Exclusion criteria:

Exclusion criteria consisted of renal, hepatic or neurological dysfunction or use of benzodiazepines, anticonvulsants, alcohol, opioids or other psychotropic drugs.

N total at baseline:

Intervention: 15

Control: 15

Important prognostic factors:

Age ± SD:

I: 39 ± 4.50

C: 41.21 ± 5.07

Sex (M/F):

I: 9/6

C: 11/4

BMI ± SD:

I: 43.2 ± 5.07

C: 45.8 ± 7.5

Groups comparable at baseline?

The two groups were similar in age, height, age, weight, BMI and duration of anesthesia.

BIS monitoring

The second group, (15 patients) sevoflurane was titrated to maintain a BIS value between 40 and 60 during surgery, and then 60-70 during 15 min prior to the end of surgery (BIS group).

- BIS group: the anesthesiologist had access to the monitor and

adjusted the concentration of sevoflurane to achieve a target BIS in the

range 40-60.

No BIS monitoring

First group, (15 patients) were anesthetized without the use of BIS (non BIS or control group), and sevoflurane being administered according to standard clinical practice.

- No BIS (control) group: the anesthesiologist adjusted the sevoflurane concentration purely according to the clinical signs.

Length of follow-up:

Not reported. The authors do not state how long they continued to follow-up patients, but patients were asked about recall at 24 hours after surgery.

Loss-to-follow-up:

Not reported.

Incomplete outcome data:

Not reported.

Patient-reported awareness:

Question at time of discharge from recovery room and 24h after surgery, whether they had dreams or recalled any intraoperative events.

Recall of intraoperative events

I: 0

C: 0

Mortality:

Not explicitly reported, but all patients were completely awake during the three postoperative hours without complications.

I: 0

C: 0

Cardiovascular complications

Not explicitly reported, but all patients were completely awake during the three postoperative hours without complications.

I: 0

C: 0

Length of stay:

Not reported.

Time to exctubation:

Recovery times (in minutes): extubation (mean ± SD),

I: 9.26 ± 2.01

C: 11.80 ± 2.9

MD: -2.54 (95% CI: -4.33, -0.75)

Author’s conclusion:

In conclusion, the recovery variables were shorter with BIS monitoring which in turn made significant savings in sevoflurane consumption and influenced the speed of recovery after laparoscopic gastric banding in morbidly obese patients.

Ibrabim, 2013

Type of study: RCT

Setting and country: University hospital, Zagazig, Egypt

Funding and conflicts of interest:

Source of Support: Nil.

Conflict of Interest: None declared.

Inclusion criteria:

After local institutional review board approval was obtained and all patients gave informed written consent, 40 morbidly obese patients [body mass index (BMI) >35 kg/m2 and ASA physical status II–III] undergoing laparoscopic sleeve gastrectomy were included in the study.

Exclusion criteria:

Exclusion criteria were memory impairment, psychosis, known or suspected electroencephalograph abnormality (e.g., epilepsy, previous brain operation), chronic use of psychoactive medication, and operation time exceeding 6 h.

N total at baseline:

I: 20

C: 20

Important prognostic factors:

Age ± SD:

I: 36.07 ± 3.5

C: 34.12 ± 4.2

Gender (F/M):

I: 14/6

C: 15/5

BMI ± SD:

I: 44.04 ± 3.5

C: 45.51 ± 4.6

Groups comparable at baseline.

There were no significant differences between the two groups regarding demographic data (age, height, weight; BMI) or duration of anesthesia and surgery

Desflurane was titrated to maintain a BIS value between 40 and 60 during surgery, and then to 60–70 during 15 min before the end of surgery.

Desflurane 6% in 2 l/min fresh gas flow, mixed in air and oxygen, was administered to all patients after endotracheal intubation until skin incision; then the concentration was changed every 5 min as follows: in BIS group, the anesthesiologist adjusted the concentration of desflurane to achieve a target BIS in the range 40-60. End-tidal concentration of desflurane was also regularly recorded (by Datex-Ohmeda S/5 monitor). During the operation, the patients in both groups were observed for signs of inadequate anesthesia (increased BP and HR 20% from baseline, lacrimation). Significant hypotension or bradycardia was defined as 20% reduction of the baseline figures. Any instances of inadequate anesthesia were managed by increasing the concentration of desflurane. Rocuronium neuromuscular blockade was maintained to a single twitch of the train of four. During the last 15 min of surgery, in the BIS group, the BIS value was gradually titrated to 60-70 by decreasing the inhaled anesthetic concentration.

Desflurane was administered according to standard clinical practice.

Desflurane 6% in 2 l/min fresh gas flow, mixed in air and oxygen, was administered to all patients after endotracheal intubation until skin incision; then the concentration was changed every 5 min as follows: Non-BIS group (control group), the anesthesiologist adjusted the desflurane concentration purely according to the clinical signs [heart rate (HR) and BP].

Length of follow-up:

Not reported. The authors do not state how long they continued to follow-up patients, but patients were asked about recall at 24 hours after surgery

Loss-to-follow-up:

Not reported.

Incomplete outcome data:

Not reported.

Patient-reported awareness:

Question at time of discharge from recovery room and 24h after surgery, whether they had bad dreams or recalled any intraoperative events.

Recall of intraoperative events

I: 0

C: 0

Mortality:

Not reported.

Cardiovascular complications

“all patients were completely awake and discharged after 3 h from PACU without complications.”

Length of stay:

Not reported.

Time to extubation:

Mean time in minutes ± SD

I: 6.4 ± 1.4

C: 8.2 ± 3.1

MD: -1.80 (95% CI: -3.29, -0.31)

Author’s conclusion: The use of BIS monitoring was effective in reducing intraoperative desflurane requirement (cost) and in shortening early recovery times after laparoscopic sleeve gastrectomy in morbidly obese patients without compromising the hemodynamic stability, adequacy of anesthesia, or patient outcome.

Siampalioti, 2015

Type of study: RCT

Setting and country:

University Hospital of Patras,

Greece

Funding and conflicts of interest: The authors declared that there were no conflicts of interest.

Inclusion criteria:

Super obese patients (with body mass index greater than 50 kg/m²), aged 21 to 60 years old were recruited for this prospective randomized controlled study. All patients undergoing elective bariatric surgery were scheduled to have a variant of biliopancreatic diversion.

Exclusion criteria:

Patients with severe cardiopulmonary disease (aortic stenosis, angina, chronic heart failure, previous cardiac or intrathoracic operations), significant renal dysfunction (serum creatinine > 1.8 mg/dl), liver dysfunction (evidenced by abnormal LFTs), history of hyper or hypothyroidism, serious psychiatric or neurologic disorders, recall during general anesthesia, allergy to local anesthetics, history of substance abuse (alcohol or other drugs), contra indications for placement of thoracic epidural catheter (previous spine surgery,

coagulation abnormalities) and patients who refused to participate were excluded from the study.

Comparison 1:

N total at baseline:

I1: 25

C1:25

Important prognostic factors:

Age ± SD:

I1: 36 ± 10

C1: 42 ± 8

Gender M/F:

I1: 7/18

C1: 10/15

BMI ± SD:

I1: 57 ± 9

C1: 61 ± 10

Comparison 2:

N total at baseline:

I2: 25

C2: 25

Important prognostic factors:

Age ± SD:

I2: 37 ± 9

C2: 36 ± 9

Gender M/F:

I2: 6/19

C2: 8/17

BMI ± SD:

I2: 55 ± 6

C2: 59 ± 11

All groups comparable at baseline, except for comorbidity dyslipidemia

BIS monitoring

Comparison 1:

[for standard care protocol, see control group] +

In the BIS monitoring group the sevoflurane concentrations were also adjusted to maintain a BIS level between 40 and 55. For every positive sympathetic response expressed with rise of blood pressure or heart rate > 15% of the baseline, a bolus inhalation of 8% sevoflurane (fresh gas flow 6 L/min, semi-closed circuit) was administered for 2 minutes. If the positive sympathetic response persisted and HR < 70/min, nifedipine 10 mg was administered sublingually, whereas if HR > 70/min diltiazem 10-20 mg was administered IV, followed by esmolol infusion if the response to diltiazem was unsatisfactory. The duration and frequency of positive sympathetic stress responses that required pharmacologic intervention were recorded.

Comparison 2:

[for standard care protocol, see control group] +

In the BIS monitoring group the rate of propofol administration was also adjusted to maintain a BIS level between 40 and 55. For every rise of BP or HR > 15% of the baseline, a bolus dose of remifentanil 1 μg · kg-1 IBW was administered, followed by a gradual increase in the continuous infusion rate of remifentanil to 1.0 μg/kg/min. The increased dose was interrupted when hemodynamic alterations returned to baseline. For any decrease in blood pressure <15% of the baseline, continuous infusion rate of remifentanil was reduced and if no response was evident in 3 minutes etilefrine was administered. For every drop of HR < 45/min a bolus dose of atropine 0.5 mg was administered, followed by a repeated dose if no response was evident in 5 minutes. The duration and the frequency of the hemodynamic changes were recorded.

No BIS monitoring

Administration dose for all anesthetic drugs was based either on the ideal body weight (IBW), or the empirical formula of corrected body weight (CBW = IBW + [0.4 × excess weight]).

Comparison 1:

In both Sevoflurane groups, rapid sequence induction

(RSI) to anesthesia was performed with

the administration of a bolus dose of propofol 2 mg·kg-1 CBW, followed by a bolus dose of remifentanil 1 μg·kg-1 IBW and succinylcholine 1 mg·kg-1 TBW and subsequent intubation of the trachea. The correct positioning of the endotracheal tube was confirmed by capnography and bilateral lung auscultation. Anesthesia was maintained with end-tidal sevoflurane concentrations of 1-3% (Siemens Multigaz Gas Analyzer).

Comparison 2:

In both propofol groups general anesthesia was induced with a gradually reduced continuous IV propofol infusion (21 mg·kg-1 CBW for 5 min, 12 mg·kg-1 CBW for 10 min and then 6 mg·kg-1 CBW), followed by a bolus dose of remifentanil 1 μg·kg-1 IBW and succinylcholine 1 mg·kg-1 IBW. Anesthesia was maintained with continuous intravenous administration of propofol at 6-10 mg/kg/hr CBW and remifentanil at 0.1-1 μg/kg/min.

Length of follow-up:

Not reported. The authors do not state how long they continued to follow-up patients.

Loss-to-follow-up:

Not reported.

Incomplete outcome data:

Not reported.

Patient-reported awareness:

Not reported.

Mortality:

Not reported

Cardiovascular complications

While the authors state that “all episodes of postoperative hypertension, nausea, vomiting and pain exacerbation were also recorded.”, the number of these episodes were not reported.

“In our high volume specialized bariatric center a thoracic epidural catheter was placed successfully in all patients with no early or late complications.”

Length of stay:

Mean duration of stay ±SD

units not specified

Comparison 1

I1: 8 ± 1

C1: 8 ± 1

MD: 0.00 (95% CI: -0.55, 0.55)

Comparison 2

I2: 8 ± 1

C2: 8

MD: not estimable.

Time to extubation:

Mean time in minutes ± SD

Comparison 1

I1: 24.7 ± 11.68

C1: 25.19 ± 13.7

MD: -0.49 (95% CI: -7.55, 6.57)

Comparison 2

I2: 10.96 ± 5.45

C2: 10.67 ± 4.26

MD: 0.29 (95% CI: -2.42, 3.00)

Study reference

(first author, publication year)

Was the allocation sequence adequately generated?

Definitely yes

Probably yes

Probably no

Definitely no

Was the allocation adequately concealed?

Definitely yes

Probably yes

Probably no

Definitely no

Blinding: Was knowledge of the allocated interventions adequately prevented?

Were patients blinded?

Were healthcare providers blinded?

Were data collectors blinded?

Were outcome assessors blinded?

Were data analysts blinded?

Definitely yes

Probably yes

Probably no

Definitely no

Was loss to follow-up (missing outcome data) infrequent?

Definitely yes

Probably yes

Probably no

Definitely no

Are reports of the study free

of selective outcome reporting?

Definitely yes

Probably yes

Probably no

Definitely no

Was the study apparently free of other problems that could put it at a risk of bias?

Definitely yes

Probably yes

Probably no

Definitely no

Overall risk of bias

If applicable/necessary, per outcome measure

LOW

Some concerns

HIGH

Ibraheim, 2008

Probably yes

Reason: “Patients were randomly assigned to two groups.”

Method not reported.

No information.

Probably yes

Reason: “In the present study, the protocol was designed as a single blinded comparison of the anesthetic administration, as sevoflurane was titrated intraoperatively against objective measures such as BIS, HR, MAP, and patient movements. Early recovery in the operative room (time to awakening and to extubation) was assessed by another anesthesia provider, that does not constitute an investigator associated bias. In addition, in the PACU, the nursing staff had no knowledge of the study.”

Probably yes

Reason: Not explicitly reported, but the number of patients in the outcome section is the same as the number of patients randomized.

Probably yes

Reason: no protocol or study registration available; all relevant outcomes mention in method section were reported.

Probably yes. No other problems noted.

Some concerns

Reason: overall study quality: lack of detailed information (e.g. about the allocation sequence and concealment) and no study protocol available.

Ibrahim, 2013

Probably yes

Reason: “Patients were randomly allocated into two groups.” Method not reported.

No information.

Probably yes

Reason: This study was designed to be a prospective randomized controlled single-blinded study as desflurane was titrated intraoperatively against objective measures such as BIS, HR, MAP, and end-tidal desflurane concentration. Early recovery times in the operating room (eye opening to verbal commands, extubation time, and orientation to time, place, and person) were also recorded by a blinded study anesthesia nurse, which may not constitute an investigator-associated bias. Also, in the PACU, the nursing staff did not have any idea about the study.

Probably yes

Reason: Not explicitly reported, but the number of patients in the outcome section is the same as the number of patients randomized.

Probably yes

Reason: no protocol or study registration available; all relevant outcomes mention in method section were reported.

Probably yes. No other problems noted.

Some concerns

Reason: overall study quality: lack of detailed information (e.g. about the allocation sequence and concealment) and no study protocol available.

Siampalioti, 2015

Definitely yes

Reason: “All patients were randomly divided into four groups via a computer-generated random number table.”

No information.

Probably yes

Reason: “Both the anesthesiologist performing the assessment and the patients were blinded to the general anesthetic used and the BIS monitoring. [...]

All data were collected by a blinded investigator.”

Probably yes

Reason: Not explicitly reported, but the number of patients in the outcome section is the same as the number of patients randomized.

Definitely yes

Reason: All relevant outcomes were reported.

Trial registered: NCT01279499

Incomplete information: for the outcome length of stay: no specification of time units and SD not reported for one of the groups.

Probably yes. No other problems noted.

Some concerns

Reason: no information on allocation, not all information about the study outcomes was clearly described and complete.