Thomas Bluth

Effects of Volatile Anesthetics on Mortality and Postoperative Pulmonary and Other Complications in Patients Undergoing Surgery: A Systematic Review and Meta-analysis

Background:It is not known whether modern volatile anesthetics are associated with less mortality and postoperative pulmonary or other complications in patients undergoing general anesthesia for surgery. Methods:A systematic literature review was conducted for randomized controlled trials fulfilling following criteria: (1) population: adult patients undergoing general anesthesia for surgery; (2) intervention: patients receiving sevoflurane, desflurane, or isoflurane; (3) comparison: volatile anesthetics versus total IV anesthesia or volatile anesthetics; (4) reporting on: (a) mortality (primary outcome) and (b) postoperative pulmonary or other complications; (5) study design: randomized controlled trials. The authors pooled treatment effects following Peto odds ratio (OR) meta-analysis and network meta-analysis methods. Results:Sixty-eight randomized controlled trials with 7,104 patients were retained for analysis. In cardiac surgery, volatile anesthetics were associated with reduced mortality (OR = 0.55; 95% CI, 0.35 to 0.85; P = 0.007), less pulmonary (OR = 0.71; 95% CI, 0.52 to 0.98; P = 0.038), and other complications (OR = 0.74; 95% CI, 0.58 to 0.95; P = 0.020). In noncardiac surgery, volatile anesthetics were not associated with reduced mortality (OR = 1.31; 95% CI, 0.83 to 2.05, P = 0.242) or lower incidences of pulmonary (OR = 0.67; 95% CI, 0.42 to 1.05; P = 0.081) and other complications (OR = 0.70; 95% CI, 0.46 to 1.05; P = 0.092). Conclusions:In cardiac, but not in noncardiac, surgery, when compared to total IV anesthesia, general anesthesia with volatile anesthetics was associated with major benefits in outcome, including reduced mortality, as well as lower incidence of pulmonary and other complications. Further studies are warranted to address the impact of volatile anesthetics on outcome in noncardiac surgery.

Kinetics of plasma biomarkers of inflammation and lung injury in surgical patients with or without postoperative pulmonary complications.

BACKGROUND Postoperative pulmonary complications (PPCs) are common after major abdominal surgery. The kinetics of plasma biomarkers could improve identification of patients developing PPCs, but the kinetics may depend on intraoperative ventilator settings. OBJECTIVE To test whether the kinetics of plasma biomarkers are capable of identifying patients who will develop PPCs, and whether the kinetics depend on the intraoperative level of positive end-expiratory pressure (PEEP). DESIGN A preplanned substudy of a randomised controlled trial. SETTING Operation room of five centres. PATIENTS Two hundred and forty-two adult patients scheduled for abdominal surgery at risk of developing PPCs. INTERVENTIONS High (12 cmH2O) versus low (⩽2 cmH2O) levels of PEEP. MAIN OUTCOME MEASURES Individual PPCs were combined as a composite endpoint. Plasma samples were collected before surgery, directly after surgery and on the fifth postoperative day. The levels of the following were measured: tumour necrosis factor (TNF)-&agr;, interleukin (IL)-6 and IL-8, the soluble form of the Receptor for Advanced Glycation End–products (sRAGE), Surfactant Protein (SP)-D, Clara Cell protein (CC)-16 and Krebs von den Lungen 6 (KL6). RESULTS Blood sampling was complete in 242 patients: 120 patients in the high PEEP group and 122 patients in the low PEEP group. Increases in plasma levels of TNF- IL-6, IL-8 and CC-16, and a decrease in plasma levels of SP-D were greater in patients who developed PPCs; however, the area under the receiver operating characteristic curve was low for all biomarkers. CC-16 was the only biomarker whose level increased more in patients who had received high levels of PEEP. CONCLUSION In patients undergoing abdominal surgery and at risk of developing PPCs, plasma levels of biomarkers for inflammation or lung injury showed distinct kinetics with development of PPCs, but none of the biomarkers showed sufficient prognostic value. The use of high levels of PEEP was associated with increased levels of CC-16, suggesting lung overdistension. TRIAL REGISTRATION The PROVHILO trial, including this substudy, was registered at clinicaltrials.gov (NCT01441791).

Effects of Ultraprotective Ventilation, Extracorporeal Carbon Dioxide Removal, and Spontaneous Breathing on Lung Morphofunction and Inflammation in Experimental Severe Acute Respiratory Distress Syndrome

Background:To investigate the role of ultraprotective mechanical ventilation (UP-MV) and extracorporeal carbon dioxide removal with and without spontaneous breathing (SB) to improve respiratory function and lung protection in experimental severe acute respiratory distress syndrome. Methods:Severe acute respiratory distress syndrome was induced by saline lung lavage and mechanical ventilation (MV) with higher tidal volume (VT) in 28 anesthetized pigs (32.8 to 52.5 kg). Animals (n = 7 per group) were randomly assigned to 6 h of MV (airway pressure release ventilation) with: (1) conventional P-MV with VT ≈6 ml/kg (P-MVcontr); (2) UP-MV with VT ≈3 ml/kg (UP-MVcontr); (3) UP-MV with VT ≈3 ml/kg and SB (UP-MVspont); and (4) UP-MV with VT ≈3 ml/kg and pressure supported SB (UP-MVPS). In UP-MV groups, extracorporeal carbon dioxide removal was used. Results:The authors found that: (1) UP-MVcontr reduced diffuse alveolar damage score in dorsal lung zones (median[interquartile]) (12.0 [7.0 to 16.8] vs. 22.5 [13.8 to 40.8]), but worsened oxygenation and intrapulmonary shunt, compared to P-MVcontr; (2) UP-MVspont and UP-MVPS improved oxygenation and intrapulmonary shunt, and redistributed ventilation towards dorsal areas, as compared to UP-MVcontr; (3) compared to P-MVcontr, UP-MVcontr and UP-MVspont, UP-MVPS yielded higher levels of tumor necrosis factor-&agr; (6.9 [6.5 to 10.1] vs. 2.8 [2.2 to 3.0], 3.6 [3.0 to 4.7] and 4.0 [2.8 to 4.4] pg/mg, respectively) and interleukin-8 (216.8 [113.5 to 343.5] vs. 59.8 [45.3 to 66.7], 37.6 [18.8 to 52.0], and 59.5 [36.1 to 79.7] pg/mg, respectively) in dorsal lung zones. Conclusions:In this model of severe acute respiratory distress syndrome, MV with VT ≈3 ml/kg and extracorporeal carbon dioxide removal without SB slightly reduced lung histologic damage, but not inflammation, as compared to MV with VT = 4 to 6 ml/kg. During UP-MV, pressure supported SB increased lung inflammation.

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a randomised controlled trial

Background: Experimental studies showed that controlled variable ventilation (CVV) yielded better pulmonary function compared to non‐variable ventilation (CNV) in injured lungs. We hypothesized that CVV improves intraoperative and postoperative respiratory function in patients undergoing open abdominal surgery. Methods: Fifty patients planned for open abdominal surgery lasting >3 h were randomly assigned to receive either CVV or CNV. Mean tidal volumes and PEEP were set at 8 ml kg−1 (predicted body weight) and 5 cm H2O, respectively. In CVV, tidal volumes varied randomly, following a normal distribution, on a breath‐by‐breath basis. The primary endpoint was the forced vital capacity (FVC) on postoperative Day 1. Secondary endpoints were oxygenation, non‐aerated lung volume, distribution of ventilation, and pulmonary and extrapulmonary complications until postoperative Day 5. Results: FVC did not differ significantly between CVV and CNV on postoperative Day 1, 61.5 (standard deviation 22.1) % vs 61.9 (23.6) %, respectively; mean [95% confidence interval (CI)] difference, −0.4 (−13.2–14.0), P=0.95. Intraoperatively, CVV did not result in improved respiratory function, haemodynamics, or redistribution of ventilation compared to CNV. Postoperatively, FVC, forced expiratory volume at the first second (FEV1), and FEV1/FVC deteriorated, while atelectasis volume and plasma levels of interleukin‐6 and interleukin‐8 increased, but values did not differ between groups. The incidence of postoperative pulmonary and extrapulmonary complications was comparable in CVV and CNV. Conclusions: In patients undergoing open abdominal surgery, CVV did not improve intraoperative and postoperative respiratory function compared with CNV. Clinical trial registration: NCT 01683578.

Intraoperative ventilation settings and their associations with postoperative pulmonary complications in obese patients

Background: There is limited information concerning the current practice of intraoperative mechanical ventilation in obese patients, and the optimal ventilator settings for these patients are debated. We investigated intraoperative ventilation parameters and their associations with the development of postoperative pulmonary complications (PPCs) in obese patients. Methods: We performed a secondary analysis of the international multicentre Local ASsessment of VEntilatory management during General Anesthesia for Surgery’ (LAS VEGAS) study, restricted to obese patients, with a predefined composite outcome of PPCs as primary end‐point. Results: We analysed 2012 obese patients from 135 hospitals across 29 countries in Europe, North America, North Africa, and the Middle East. Tidal volume was 8.8 [25th–75th percentiles: 7.8–9.9] ml kg−1 predicted body weight, PEEP was 4 [1–5] cm H2O, and recruitment manoeuvres were performed in 7.7% of patients. PPCs occurred in 11.7% of patients and were independently associated with age (P<0.001), body mass index ≥40 kg m−2 (P=0.033), obstructive sleep apnoea (P=0.002), duration of anaesthesia (P<0.001), peak airway pressure (P<0.001), use of rescue recruitment manoeuvres (P<0.05) and routine recruitment manoeuvres performed by bag squeezing (P=0.021). PPCs were associated with an increased length of hospital stay (P<0.001). Conclusions: Obese patients are frequently ventilated with high tidal volume and low PEEP, and seldom receive recruitment manoeuvres. PPCs increase hospital stay, and are associated with preoperative conditions, duration of anaesthesia and intraoperative ventilation settings. Randomised trials are warranted to clarify the role of different ventilatory parameters in obese patients. Clinical trial registration: NCT01601223.

Perioperative complications of obese patients.

Purpose of reviewThe perioperative care of obese patients can often be challenging, as the presence of comorbidities is common in this patient population. In this article, we present recent data on perioperative complications of obese patients and discuss relevant details for daily practice, including drug dosing, airway management, and mechanical ventilation. Recent findingsThe volatile agent desflurane reduces extubation time, without major effects on postoperative anesthesia care unit discharge time, incidence of postoperative nausea and vomiting, or postoperative pain scores compared with other volatile anesthetics. Lean body weight is the most appropriate dosing scalar for most drugs used in anesthesia, including opioids and anesthetic induction agents. Compared with the operational theatre, airway complications occur 20-fold more often in the ICU, with poor outcome. Individual titration of positive end-expiratory pressure (PEEP) after lung recruitment improves gas exchange and lung mechanics intraoperatively, but data on patient outcome are lacking. SummaryIntensive care physicians who treat obese patients need to be trained in the management of the difficult airway. The application of PEEP and the use of recruitment maneuvers may lead to improved intraoperative oxygenation, but current data do not allow recommending the use of high PEEP combined with lung recruitment maneuvers in this population.

Anästhesie bei endourologischen und roboterassistierten Eingriffen

The improved drug therapy leads to increasingly older patients with complex comorbidities in the discipline of operative urology. Today, improved technical equipment provides new operational capabilities in the field of urology. The prone and lithotomy position during surgery leads to physiological changes that affect anesthesia management. The surgical risk of procedures such as transurethral surgery of the prostate or bladder is being altered by laser surgery and other new technologies. Although the incidence of transurethral resection (TUR) syndrome has been reduced in recent years, the intrusion of irrigation fluid still has to be considered during anesthesia. Robot-assisted surgery has successfully completed the experimental stage and is widely used so that new targets have to be challenged. Ureterorenoscopy is performed with flexible, small caliber ureteroscopes which even allow treatment of renal calculi under analgosedation within short time periods. Percutaneous nephrostomy and litholapaxy are still frequently performed in the prone position. With respect to the risks arising from patient positioning, supine or lateral positioning should be considered in individual cases. A good communication between the surgeon and anesthetist allows deviation from daily routine procedures if special indications require a modified approach. In conclusion, a profound knowledge of the (patho-)physiology of general anesthesia and endourological diseases enables anesthetists to provide a prospective type anesthesia, which should prevent the occurrence of life-threatening incidents.

Periodic Fluctuation of Tidal Volumes Further Improves Variable Ventilation in Experimental Acute Respiratory Distress Syndrome

In experimental acute respiratory distress syndrome (ARDS), random variation of tidal volumes (VT) during volume controlled ventilation improves gas exchange and respiratory system mechanics (so-called stochastic resonance hypothesis). It is unknown whether those positive effects may be further enhanced by periodic VT fluctuation at distinct frequencies, also known as deterministic frequency resonance. We hypothesized that the positive effects of variable ventilation on lung function may be further amplified by periodic VT fluctuation at specific frequencies. In anesthetized and mechanically ventilated pigs, severe ARDS was induced by saline lung lavage and injurious VT (double-hit model). Animals were then randomly assigned to 6 h of protective ventilation with one of four VT patterns: (1) random variation of VT (WN); (2) P04, main VT frequency of 0.13 Hz; (3) P10, main VT frequency of 0.05 Hz; (4) VCV, conventional non-variable volume controlled ventilation. In groups with variable VT, the coefficient of variation was identical (30%). We assessed lung mechanics and gas exchange, and determined lung histology and inflammation. Compared to VCV, WN, P04, and P10 resulted in lower respiratory system elastance (63 ± 13 cm H2O/L vs. 50 ± 14 cm H2O/L, 48.4 ± 21 cm H2O/L, and 45.1 ± 5.9 cm H2O/L respectively, P < 0.05 all), but only P10 improved PaO2/FIO2 after 6 h of ventilation (318 ± 96 vs. 445 ± 110 mm Hg, P < 0.05). Cycle-by-cycle analysis of lung mechanics suggested intertidal recruitment/de-recruitment in P10. Lung histologic damage and inflammation did not differ among groups. In this experimental model of severe ARDS, periodic VT fluctuation at a frequency of 0.05 Hz improved oxygenation during variable ventilation, suggesting that deterministic resonance adds further benefit to variable ventilation.

Anästhesie in der Urologie

Die perioperative Betreuung urologischer Patienten ist haufig anspruchsvoll, aber auch abwechslungsreich: Regionalanasthesien besitzen wie die Allgemeinanasthesie einen festen Stellenwert als Anasthesieverfahren, und das Alter reicht von Kindern bis hin zu geriatrischen Patienten. Neben grosen, recht standardisierten Eingriffen wie der Prostatektomie oder Zystektomie finden komplexe endourologische Eingriffe statt, z. B. zur Harnableitung bei supravesikalem Harnstau. Die Anasthesie in der Urologie eignet sich demnach nicht nur hervorragend als Einstieg in das Fachgebiet, sondern erfordert mitunter die gesamte facharztliche Expertise.

Anästhesie bei endourologischen und roboterassistierten Eingriffen@@@Anesthesia in endourological and robot-assisted interventions

The improved drug therapy leads to increasingly older patients with complex comorbidities in the discipline of operative urology. Today, improved technical equipment provides new operational capabilities in the field of urology. The prone and lithotomy position during surgery leads to physiological changes that affect anesthesia management. The surgical risk of procedures such as transurethral surgery of the prostate or bladder is being altered by laser surgery and other new technologies. Although the incidence of transurethral resection (TUR) syndrome has been reduced in recent years, the intrusion of irrigation fluid still has to be considered during anesthesia. Robot-assisted surgery has successfully completed the experimental stage and is widely used so that new targets have to be challenged. Ureterorenoscopy is performed with flexible, small caliber ureteroscopes which even allow treatment of renal calculi under analgosedation within short time periods. Percutaneous nephrostomy and litholapaxy are still frequently performed in the prone position. With respect to the risks arising from patient positioning, supine or lateral positioning should be considered in individual cases. A good communication between the surgeon and anesthetist allows deviation from daily routine procedures if special indications require a modified approach. In conclusion, a profound knowledge of the (patho-)physiology of general anesthesia and endourological diseases enables anesthetists to provide a prospective type anesthesia, which should prevent the occurrence of life-threatening incidents.