N = 98 patients were included into the present study. All patients underwent elective bariatric minimal invasive surgery, namely either sleeve gastrectomies or Roux-Y bypass reconstructions. Survey period was from August 1, 2015, to December 31, 2015.
The ethics vote for CESARO study was granted by the local independent ethics committee (ref. : EA1/220/13, chairman Prof. Dr R. Uebelhack) of Charité-Universitätsmedizin Berlin (NCT01964274) and written informed consent was obtained from each patient. Furthermore, all local data privacy regulations were followed.
The following conditions were determined as inclusion criteria for the present analysis: laboratory measurements have to be less than 4 weeks old; patients need to be at least 18 years old, elective general anesthesia must be followed by monitoring in the recovery room or admission to a postanesthesia care unit and patients should be hospitalized for at least 24 h after surgery.
Patients with already known pseudocholinesterase deficiency, patients with speech, vision or hearing disorders and patients with illiteracy or insufficient knowledge of German or English were excluded from this study. Furthermore, participation was not possible in case of unwillingness to store and share pseudonomized patient´s data. Patients in prison or similar institutions (AMG § 40), patients working in our study center, patients who participate in another prospective clinical intervention study or shown a RASS score lower than − 2 were also excluded from this study.
Patients with diabetes mellitus received capillary blood glucose monitoring preoperatively. If capillary blood glucose limit was exceeded, insulin therapy was adjusted. For surgery, standardized general anesthesia was performed without prior premedication. For induction, 3.5 mg/kg propofol, 0.15 µg/kg sufentanyl, and 1.5 mg/kg succinylcholine were used. Anesthesia was maintained in balanced form using desflurane + O2/room air mixture according to MAC with a target range of 0.8–1.2, 0.05–0.15 µg/Kg/min remifentanyl and relaxometry-guided rocuronium. For further analgesia, 1–2 g of dipypirone was used regularly. In case of more analgesia requirement, additional 0.5 mg/kg ketamine or 40 mg parecoxib was applicated. Antiemetic prophylaxis was provided applicating 4–8 mg dexamethasone and 8 mg ondansetron or 10 mg metoclopramide. In case of relaxant overload at the end of surgery pyridostigmine and atropine were administered to antagonize muscle relaxation. Intraoperative hypotension was treated with Akrinor (Theodrenalin/Cafedrin) or norepinephrine, aiming for MAP > 65 mmHg and less than 20% deviation from baseline. Ventilation was pressure-controlled with positive end-expiratory pressure (PEEP) between 8–15 mmHg, FiO2 0.4–0.7 aiming SaO2 > 90%. Intraoperative monitoring consisted of 3-lead ECG, 3-minute Riva Rocci blood pressure measurement, continuous measurement of oxygen saturation (SaO2), ventilation and respiratory parameters and depth of relaxation. Piritramide was titrated for postoperative pain management in the recovery room; supplemental 40 mg parecoxib was given if analgesia was inadequate. All patients received temporary CPAP therapy in recovery room.
Preoperatively various parameters were analyzed, including baseline data, comorbidities, standard laboratory parameters and the use of various scores.
The following parameters were collected: age, gender, type and duration of surgery and anesthesia, length of stay in the recovery room, and length of stay in hospital.
Comorbidities, especially arterial hypertension, heart disease, diabetes mellitus, COPD, obstructive sleep apnea (OSAS) and depression were extracted from premedical history. Alcohol and nicotine consumption as well as any regular medication have also been documented.
All patients underwent preoperative routine laboratory tests (see Table 1).
routinely assessed parameters
red blood count
Leukocytes, Erythrocyten, Hemoglobin, Hematokrit, MCV, MCH, MCHC, Thrombocytes, RDW
INR, pTT sec, Quick %
Liver- und lipid metabolism parameter
GOT µmol/ls, GPT µmol/ls, γ-GT µmol/ls, Bili µmol/ls, Chol. mmol/l
GFR ml/min, Creatinin mmol/l, BUN µmol/l, BUN/Crea-Quotient, uric acid mmol/l, Sodium µmol/l, Potassium mmol/l
TSH mU/l, Serum glucose mmol/l, HbA1c %
Patients were categorized using the ASA risk classification, which is intended to provide information about patient´s general physical condition (16). To estimate the risk for obstructive sleep apnea syndrome the STOP-BANG score was used (17). A cut-off value of ≥ 5 is associated with a high risk of obstructive sleep apnea.
We used the Nursing Delirium Screening Scale (Nu-Desc) according to Gaudreau et al. (18) for delirium detection in recovery room. Nu-Desc is a nursing-based tool for standardized diagnosis of POD based on criteria of DSM-IV. The questionnaire asks for the following topics: disorientation, inappropriate behavior, inappropriate communication, illusions / hallucinations and psychomotoric retardation. Usually, this score is raised by nurses and the individual parts score from 0 to 2. If the total score reaches 2 points or more, the patient has delirium.
The score was assessed three times (before starting anesthesia as baseline, 10 minutes after arrival in the recovery room and at the time leaving the recovery room).
The Richmond Agitation-Sedatation Scale (RASS) is a clinical scale to assess the individual depth of sedation and agitation. The scale ranges between + 4 (violent) and − 5 (comatose). RASS Score was used on arrival in the recovery room and 10 minutes later.
In order to investigate the relationship between pre-existing diseases, laboratory abnormalities and the occurrence of POD, patients with missing laboratory values were excluded from this study. Moreover, patients with RASS- Score < -2 could not be diagnosed with delirium, which also led to exclusion.
The statistical evaluation was performed using SPSS Statistics 23 (19). First, descriptive statistics were calculated (age, gender distribution, BMI, type of surgery, duration of surgery, duration of the AWR stay and length of hospital stay). Participants were then divided in two groups, depending on occurrence of POD. Afterwards, the groups were compared for differences in surveyed parameters. For Interpretations significance level of alpha < 0.05 was chosen.
To estimate associations of these variables with the risk of POD, variables that differed significantly and marginally not significantly between groups, were included in univariate logistic regression models, where the presence of postoperative delirium according to Nu-DESC was chosen as the dependent variable.
Finally, in order to determine adjusted odds ratios and confidence intervals, the significant and marginally insignificant variables from the univariate analyses were combined in a multivariate logistic regression model. Backward elimination was carried out using likelihood method.