Valter Perilli

The effects of the reverse Trendelenburg position on respiratory mechanics and blood gases in morbidly obese patients during bariatric surgery

Anesthesia adversely affects respiratory function, particularly in morbidly obese patients. Although many studies have been performed to determine the optimal ventilatory settings in these patients, this question has not been answered. The aim of this study was to evaluate the effect of reverse Trendelenburg position (RTP) on gas exchange and respiratory mechanics in 15 obese patients undergoing biliopancreatic diversion. A standardized anesthetic regimen was used and patients were examined at standard times: 1) after tracheal intubation, 2) after laparotomy, 3) after positioning of subcostal retractors, 4) with retractors in RTP. The measurements of respiratory mechanics were repeated for a wide range of tidal volumes by using the technique of rapid occlusion during constant flow inflation. We noted a wide alveolar-arterial oxygen difference [P(A−a)o2] in all patients, particularly during Phase 3. When the patients were placed in RTP, P(A−a)o2 showed a significant improvement and a return toward baseline values. As for mechanics, total respiratory system compliance was significantly higher in RTP than in the other phases. In conclusion, our data suggest that RTP is an appropriate intraoperative posture for obese subjects because it causes minimal arterial blood pressure changes and improves oxygenation. Implications The aim of the study was to assess whether the reverse Trendelenburg position could improve pulmonary gas exchange in obese patients undergoing abdominal surgical procedures. Our work may have a clinical value because few studies deal with this issue.

Comparison of Positive End-Expiratory Pressure with Reverse Trendelenburg Position in Morbidly Obese Patients Undergoing Bariatric Surgery: Effects on Hemodynamics and Pulmonary Gas Exchange

Background: Anesthetized morbidly obese patients often exhibit impaired pulmonary gas exchanges, mostly because of a reduction in functional residual capacity. At present, several approaches are suggested to ventilate these patients. Methods: The efficiency of positive end-expiratory pressure (PEEP) and reverse Trendelenburg position (RTP) were compared in order to improve oxygenation in 20 morbidly obese patients undergoing bariatric surgery. Results: Both PEEP and RTP determined a significant decrease in alveolar-arterial oxygen difference and an increase in total respiratory compliance (Ctot). RTP resulted in lower airway pressures than PEEP with similar improvements in Ctot and oxygenation. Concerning hemodynamic parameters, cardiac output (CO) significantly decreased with both PEEP and RTP. Conclusions: RTP and PEEP can be considered adequate ventilatory settings for morbidly obese patients, without any significant difference with regard to gas exchange improvement. However, the decrease in CO may partially counteract the beneficial effects on oxygenation of these ventilatory settings.

Endoscopic adrenalectomy: Is there an optimal operative approach? Results of a single-center case-control study

BACKGROUND The choice in between the laparoscopic lateral transabdominal (LTA) or the posterior retroperitoneoscopic (PRA) approach for adrenalectomy is usually based on surgeons preference, rather than on objective arguments. We compared the intraoperative and postoperative outcomes of LTA and PRA to determine whether there is a preferable approach. METHODS Thirty-eight consecutive patients successfully underwent PRA for benign adrenal tumors </=6 cm. A case-control study including 38 patients who successfully underwent LTA was performed. Operative time, intraoperative ventilatory parameters (CO(2) production [Vco(2)], whole body oxygen consumption, arterial partial pressure of carbon dioxide [Paco(2)], and arterial partial pressure of oxygen [Pao(2)]), final histology, complications, postoperative stay, analgesic requirement, time to regain normal bowel function, and time to return to work were recorded and compared between the 2 groups. RESULTS The 2 groups did not differ in terms of operative time, analgesic requirement, time to first flatus, complication rate, duration of postoperative stay, or final histology. Patients in the LTA group showed significantly lower Paco(2), Pao(2), and Vco(2) at the end of the operation. Patients in the PRA group experienced a significantly faster return to work. CONCLUSION No procedure can be considered preferable overall. In cases of bilateral adrenalectomy and previous abdominal surgery, PRA may offer some advantages. Surgeons preference and experience will continue to guide this choice.

Volatile Anesthesia in Bariatric Surgery

Background: Obesity causes anesthesiologists a broad variety of perioperative theoretical and practical problems. The aim of this study was to compare two protocols of anesthesia employing Isoflurane and Sevoflurane and evaluate the cardiorespiratory parameters, postoperative recovery and analgesia. Methods: 90 patients underwent biliopancreatic diversion. 60 patients (group A) received Isoflurane and 30 patients (group B) were anesthetized with Sevoflurane. Intraoperative monitoring consisted of EKG, invasive arterial pressure, Sp02, EtCO2, Etanest, Spirometry, urinary output and TOF. Cardiorespiratory parameters and end tidal expiratory concentrations of volatile agents were collected during specific phases of surgery: 1) before induction of anesthesia, 2) after intubation, 3) after skin incision, 4) after positioning of costal retractors, 5) in the reverse Trendelenburg position, 6) end of surgery. During the postoperative period the Aldrete test was carried out to evaluate the recovery from anesthesia. VAS was administered for 6 hours after the end of surgery to set the quality of analgesia. Results: No statistically significant differences in cardiorespiratory parameters were found between the two groups. Extubation time was significantly less in the Sevoflurane Group than in the Isoflurane (15 ± 7 min vs 24 ± 5 min, p< 0.05). The Sevoflurane Group showed an Aldrete score significantly higher than the Isoflurane (8.8 ± 0.3 vs 8.1 ± 0.4, p < 0.05). VAS values did not show statistical differences. Conclusion: The introduction of Sevoflurane, a volatile agent with rapid pharmacokinetic properties, seems to offer an interesting application in these patients.

Preinductive use of clonidine and ketamine improves recovery and reduces postoperative pain after bariatric surgery

BACKGROUND In obese patients, concomitant use of clonidine and ketamine might be suitable to reduce the doses and minimize the undesired side effects of anesthetic and analgesic drugs. In this study, we evaluated the perioperative effects of administration of clonidine and ketamine in morbidly obese patients undergoing weight loss surgery at a university hospital in Rome, Italy. METHODS A total of 50 morbidly obese patients undergoing open biliopancreatic diversion for weight loss surgery were enrolled. The patients were randomly allocated into a study group (n = 23) receiving a slow infusion of ketamine-clonidine before anesthesia induction and a control group (n = 27) who received standard anesthesia. The hemodynamic profile, intraoperative end-tidal sevoflurane and opioid consumption, tracheal extubation time, Aldrete score, postoperative pain assessment by visual analog scale, and analgesic requirements were recorded. RESULTS The patients in the study group required less end-tidal sevoflurane, lower total doses of fentanyl (3.8 +/- 0.3 gamma/kg actual body weight versus 5.0 +/- 0.2 gamma/kg actual body weight, respectively; P <.05) and had a shorter time to extubation (15.1 +/- 5 min versus 28.2 +/- 6 min, P <.05). The Aldrete score was significantly better in the postanesthesia care unit in the study group. The study group consumed less tramadol than did the control group (138 +/- 57 mg versus 252 +/- 78 mg, P <.05) and had a lower visual analog scale score postoperatively during the first 6 hours. CONCLUSION The preoperative administration of low doses of ketamine and clonidine at induction appears to provide early extubation and diminished postoperative analgesic requirements in morbidly obese patients undergoing open bariatric surgery.

Molecular adsorbent recirculating system (Mars) in patients with primary nonfunction and other causes of graft dysfunction after liver transplantation in the era of extended criteria donor organs.

Liver dysfunction is an important cause of morbidity and mortality after orthotopic liver transplantation (OLT). The Molecular Adsorbent Recirculating System (MARS) is an albumin-based dialysis system designed to enhance the excretory function of a failing liver. MARS has been successfully used in patients affected by advanced liver disease and presenting with severe cholestasis. The aim of this study was to evaluate the safety and clinical efficacy of MARS in patients with liver dysfunction after OLT. Seven patients (primary nonfunction, 2 patients; graft dysfunction, 5 patients) fulfilled the inclusion criteria of serum bilirubin level >15 mg/dL and least 1 of the following clinical signs: hepatic encephalopathy (HE) > or = grade II, hepatorenal syndrome (HRS), and intractable pruritus. Graft and patient survival rates at 6 months were 42.8% and 57.1%, respectively. All patients tolerated MARS treatment, with no adverse event. In all patients, a decrease in serum bilirubin (P < .05), bile acids (P < .05), serum creatinine, and ammonia levels was observed after treatment with MARS. A considerable improvement of HE, as well as renal and synthetic liver functions, was observed in 4 of 5 patients with graft dysfunction, but not among those with primary nonfunction. The patients with intractable pruritus showed significant improvement of this symptom after MARS therapy. Thus, MARS is a safe, therapeutic option for the treatment of liver dysfunction after OLT. Further studies are necessary to confirm whether this treatment is able to improve both graft and patient survival.

Factors affecting acute pain perception and analgesics consumption in patients undergoing bariatric surgery

BACKGROUND Previous studies performed in non-obese patients undergoing elective surgery have revealed that psychological factors may affect postoperative analgesic requirements. The aim of this observational prospective study was to investigate the extent to which psychopathological dimensions, including anxiety, depression and alexithymia, may influence postoperative pain intensity and analgesics consumption using patient-controlled analgesia (PCA) in patients undergoing bariatric surgery. METHODS 120 patients, aged 18-60years, with an ASA physical status I-II, undergoing gastric bypass were enrolled. Anxiety and depression Hamilton scales, and Toronto Alexithymia scale, were administered to patients on the day before surgery. General anesthesia was standardized. After awakening, a PCA pump with intravenous tramadol was immediately made available for a 36-hour postoperative analgesia. Visual analog scale at rest (VASr) and after coughing (VASi), and effective PCA requests number were postoperatively recorded. Pearsons correlations, Anova analyses and multiple linear regression were used for statistical purpose. RESULTS Positive correlations were found between anxiety, depression, alexithymia and all pain indicators (p<0.01). Analyses of variance showed that anxious (p<0.001), depressed (p<0.001) and alexithymic (p<0.05) patients had high pain indicators. VASr and VASi were predicted by anxiety and depression (p<0.05), but not by alexithymia; effective PCA requests number was predicted by anxiety, depression and alexithymia (p<0.001). CONCLUSIONS Obese patients with high depression, anxiety and alexithymia levels rated their pain as more intense and required a larger amount of tramadol. Pain perception intensity was predicted by anxiety and depression but not by alexithymia, whereas analgesics consumption was predicted by all the investigated psychopathological dimensions.

Lung volumes, respiratory mechanics and dynamic strain during general anaesthesia

Background: Driving pressure (&Dgr;P) represents tidal volume normalised to respiratory system compliance (CRS) and is a novel parameter to target ventilator settings. We conducted a study to determine whether CRS and &Dgr;P reflect aerated lung volume and dynamic strain during general anaesthesia. Methods: Twenty non‐obese patients undergoing open abdominal surgery received three PEEP levels (2, 7, or 12 cm H2O) in random order with constant tidal volume ventilation. Respiratory mechanics, lung volumes, and alveolar recruitment were measured to assess end‐expiratory aerated volume, which was compared with the patients individual predicted functional residual capacity in supine position (FRCp). Results: CRS was linearly related to aerated volume and &Dgr;P to dynamic strain at PEEP of 2 cm H2O (intraoperative FRC) (r=0.72 and r=0.73, both P<0.001). These relationships were maintained with higher PEEP only when aerated volume did not overcome FRCp (r=0.73, P<0.001; r=0.54, P=0.004), with 100 ml lung volume increases accompanied by 1.8 ml cm H2O−1 (95% confidence interval [1.1–2.5]) increases in CRS. When aerated volume was greater or equal to FRCp (35% of patients at PEEP 2 cm H2O, 55% at PEEP 7 cm H2O, and 75% at PEEP 12 cm H2O), CRS and &Dgr;P were independent from aerated volume and dynamic strain, with CRS weakly but significantly inversely related to alveolar dead space fraction (r=–0.47, P=0.001). PEEP‐induced alveolar recruitment yielded higher CRS and reduced &Dgr;P only at aerated volumes below FRCp (P=0.015 and 0.008, respectively). Conclusions: During general anaesthesia, respiratory system compliance and driving pressure reflect aerated lung volume and dynamic strain, respectively, only if aerated volume does not exceed functional residual capacity in supine position, which is a frequent event when PEEP is used in this setting.

Stress-related biomarkers of dream recall and implicit memory under anaesthesia

The aim of this study was to investigate whether auditory presentation of a story during general anaesthesia might influence stress hormone changes and thus affecting dream recall and/or implicit memory. One hundred and ten patients were randomly assigned either to hear a recording of a story through headphones or to have routine care with no auditory recording while undergoing laparoscopic cholecystectomy. Anaesthesia was standardised. Blood samples for cortisol and prolactin assays were collected 20 min before anaesthesia and 5 min after pneumoperitoneum. Dream recall and explicit/implicit memory were investigated upon awakening from anaesthesia and approximately 24 h after the end of the operation. Auditory presentation was associated with lower intra‐operative serum prolactin concentration compared with control (p = 0.0006). Twenty‐seven patients with recall of dreaming showed higher intra‐operative prolactin (p = 0.004) and lower cortisol (p = 0.03) concentrations compared with those without dream recall. The knowledge of this interaction might be useful in the quest to ensure postoperative amnesia.

Suction catheter guided insertion of ProSeal laryngeal mask airway: Experience by untrained physicians.

Background: The use of suction catheter (SC) has been shown to improve success rate during ProSeal laryngeal mask airway (PLMA) insertion in expert users. Aims: The aim of this study was to compare insertion of PLMA performed by untrained physicians using a SC or the digital technique (DT) in anaesthetised non-paralysed patients. Methods: In this prospective randomised double-blind study, conducted in the operating setting, 254 patients (American Society of Anaesthesiologists I-II, aged 18-65 years), undergoing minor surgery were enrolled. Exclusion criteria were body mass index >35 kg/m 2 , laryngeal or oesophageal varices, risk of aspiration or difficult face mask ventilation either referred or suspected (Langeron′s criteria ≥2) and modified Mallampati classification score >2. Participants were randomly allocated to one of the two groups in which PLMA was inserted using DT (DT-group) or SC (SC-group). Statistical Analysis: Chi-square test with Yates′ correction, Mann-Whitney U-test or Student′s t-test were carried-out as appropriate. Results: The final insertion success rate was greater in SC-groupcompared with DT-group 90.1% (n = 109) versus 74.4% (n = 99) respectively (P = 0.002). Mean airway leak pressure was higher in SC-group compared to DT-group (23.7 ± 3.9 vs. 21.4 ± 3.2 respectively; (P = 0.001). There were no differences in insertion time, post-operative airway morbidity and complications. Conclusion: The findings of this study suggest that SC-technique improves the success rate of PLMA insertion by untrained physicians.