Effect of cerebrospinal fluid drainage pressure in descending and thoracoabdominal aortic repair: a prospective multicenter observational study.

PURPOSE: Cerebrospinal fluid drainage (CSFD) is recommended during open or endovascular thoracic aortic repair. However, the incidence of CSFD complications is still high. Recently, CSF pressure has been kept high to avoid complications, but the efficacy of CSFD at higher pressures has not been confirmed. We hypothesize that CSFD at higher pressures is effective for preventing motor deficits. METHODS: This prospective observational study included 14 hospitals that are members of the Japanese Society of Cardiovascular Anesthesiologists. Patients who underwent thoracic and thoracoabdominal aortic repair were divided into four groups: Group 1, CSF pressure around 10 mmHg; Group 2, CSF pressure around 15 mmHg; Group 3, CSFD initiated when motor evoked potential amplitudes decreased; and Group 4, no CSFD. We assessed the association between the CSFD group and motor deficits using mixed-effects logistic regression with a random intercept for the institution. RESULTS: Of 1072 patients in the study, 84 patients (open surgery, 51; thoracic endovascular aortic repair, 33) had motor deficits at discharge. Groups 1 and 2 were not associated with motor deficits (Group 1, odds ratio (OR): 1.53, 95% confidence interval (95% CI): 0.71-3.29, p = 0.276; Group 2, OR: 1.73, 95% CI: 0.62-4.82) when compared with Group 4. Group 3 was significantly more prone to motor deficits than Group 4 (OR: 2.56, 95% CI: 1.27-5.17, p = 0.009). CONCLUSION: CSFD is not associated with motor deficits in thoracic and thoracoabdominal aortic repair with CSF pressure around 10 or 15 mmHg.

Prone Position Impairs Oxygen Supply-Demand Balance During Systemic Hypoxia in Rabbits.

Ventilation in the prone position improves the prognosis of patients with severe acute respiratory distress syndrome (ARDS). Contraindications to ventilation in this position include unstable systemic circulation. Only a few reports exist on the effects of prone ventilation in respiratory failure on systemic circulation. This animal study compared systemic hemodynamic changes between supine and prone positions in anesthetized rabbits under acute systemic hypoxia (breathing 15% O2). Cardiac output and the systemic O2 extraction ratio increased under the hypoxia, but only in the supine group. Besides, the rate pressure product was higher in the prone group than in the supine group. This study showed that prone ventilation increases myocardial O2 consumption and suppresses compensatory mechanisms to maintain aerobic metabolism during systemic hypoxia. First of all, it will be necessary to examine the effect of prone ventilation on the O2 supply-demand balance in the ARDS model.

Cerebrospinal fluid drainage to prevent postoperative spinal cord injury in thoracic aortic repair.

BACKGROUND: Cerebrospinal fluid drainage (CSFD) is recommended as a spinal cord protective strategy in open and endovascular thoracic aortic repair. Although small studies support the use of CSFD, systematic reviews have not suggested definite conclusion and a large-scale study is needed. Therefore, we reviewed medical records of patients who had undergone descending and thoracoabdominal aortic repair (both open and endovascular repair) at multiple institutions to assess the association between CSFD and postoperative motor deficits. METHODS: Patients included in this study underwent descending or thoracoabdominal aortic repair between 2000 and 2013 at 12 hospitals belonging to the Japanese Association of Spinal Cord Protection in Aortic Surgery. We conducted a retrospective study to investigate whether motor-evoked potential monitoring is effective in reducing motor deficits in thoracic aortic aneurysm repair. We use the same dataset to examine whether CSFD reduces motor deficits after propensity score matching. RESULTS: We reviewed data from 1214 patients [open surgery, 601 (49.5%); endovascular repair, 613 (50.5%)]. CSFD was performed in 417 patients and not performed in the remaining 797 patients. Postoperative motor deficits were observed in 75 (6.2%) patients at discharge. After propensity score matching (n = 700), mixed-effects logistic regression performed revealed that CSFD is associated with postoperative motor deficits at discharge [adjusted odds ratio (OR), 3.87; 95% confidence interval (CI), 2.30-6.51]. CONCLUSION: CSFD may not be effective for postoperative motor deficits at discharge.

Marathoners' Breathing Pattern Protects Against Lung Injury by Mechanical Ventilation: An Ex Vivo Study Using Rabbit Lungs.

BACKGROUND: Breathing during a marathon is often empirically conducted in a so-called "2:2 breathing rhythm," which is based on a four-phase cycle, consisting of the 1st and 2nd inspiratory and the 1st and 2nd expiratory phases. We developed a prototype ventilator that can perform intermittent positive pressure ventilation, mimicking the breathing cycle of the 2:2 breathing rhythm. This mode of ventilation was named the marathoners' breathing rhythm ventilation (MBV). We hypothesized that MBV may have a lung protective effect. METHODS: We examined the effects of the MBV on the pulmonary pre-edema model in isolated perfused rabbit lungs. The pulmonary pre-edema state was induced using bloodless perfusate with low colloid osmotic pressure. The 14 isolated rabbit lung preparations were randomly divided into the conventional mechanical ventilation (CMV) group and MBV group, (both had an inspiratory/expiratory ratio of 1/1). In the CMV group, seven rabbit lungs were ventilated using the Harvard Ventilator 683 with a tidal volume (TV) of 8 mL/kg, a respiratory rate (RR) of 30 cycles/min, and a positive end-expiratory pressure (PEEP) of 2 cmH2O for 60 min. In the MBV group, seven rabbit lungs were ventilated using the prototype ventilator with a TV of 6 mL/kg, an RR of 30 cycles/min, and a PEEP of 4 cmH2O (first step) and 2 cmH2O (second step) for 60 min. The time allocation of the MBV for one cycle was 0.3 s for each of the 1st and 2nd inspiratory and expiratory phases with 0.2 s of intermittent resting between each phase. RESULTS: Peak airway pressure and lung wet-to-dry ratio after 60 min of ventilation were lower in the MBV group than in the CMV group. CONCLUSION: MBV was considered to have a lung-protective effect compared to CMV.

Desflurane inhalation before ischemia increases ischemia-reperfusion-induced vascular leakage in isolated rabbit lungs.

BACKGROUND: Isoflurane and sevoflurane protect lungs with ischemia-reperfusion (IR) injury. We examined the influence of desflurane on IR lung injury using isolated rabbit lungs perfused with a physiological salt solution. METHODS: The isolated lungs were divided into three groups: IR, desflurane-treated ischemia-reperfusion (DES-IR), and ventilation/perfusion-continued control (Cont) groups (n = 6 per group). In the DES-IR group, inhalation of desflurane at 1 minimum alveolar concentration (MAC) was conducted in a stable 30-min phase. In the IR and DES-IR groups, ventilation/perfusion was stopped for 75 min after the stable phase. Subsequently, they were resumed. Each lung was placed on a balance, and weighed. Weight changes were measured serially throughout this experiment. The coefficient of filtration (Kfc) was determined immediately before ischemia and 60 min after reperfusion. Furthermore, bronchoalveolar lavage fluid (BALF) was collected from the right bronchus at the completion of the experiment. After the completion of the experiment, the left lung was dried, and the lung wet-to-dry weight ratio (W/D) was calculated. RESULTS: The Kfc values at 60 min after perfusion were 0.40 ± 0.13 ml/min/mmHg/100 g in the DES-IR group, 0.26 ± 0.07 ml/min/mmHg/100 g in the IR group, and 0.22 ± 0.08 (mean ± SD) ml/mmHg/100 g in the Cont group. In the DES-IR group, the Kfc at 60 min after the start of reperfusion was significantly higher than in the other groups. In the DES-IR group, W/D was significantly higher than in the Cont group. In the DES-IR group, the BALF concentrations of nitric oxide metabolites were significantly higher than in the other groups. In the DES-IR group, the total amount of vascular endothelial growth factor in BALF was significantly higher than in the Cont group. CONCLUSIONS: The pre-inhalation of desflurane at 1 MAC exacerbates pulmonary IR injury in isolated/perfused rabbit lungs.

Phosphoenolpyruvate administration protects ischemia-reperfusion injury in isolated rabbit lungs.

Phosphoenolpyruvate (PEP) is an intermediate metabolite of the glycolytic pathway and an in vivo high-energy phosphate compound. We have examined the protective effects of PEP on ischemia-reperfusion lung injury in isolated rabbits lungs perfused with a physiological salt solution. The lungs were divided into three treatment groups: (1) ischemia-reperfusion (IR), (2) ischemia-reperfusion with PEP treatment (PEP-IR), in which 1 mM PEP was pre-administered into the perfusate during the stable period, and (3) ventilation-perfusion continued without interruption (Cont). In the IR and PEP-IR groups, ventilation-perfusion was discontinued for about 60 min after a 30-min stable period and then restarted. The capillary filtration coefficients (K fc) and pyruvate concentration in the perfusate were determined immediately before ischemia and 30 and 60 min after reperfusion. The left lungs were dried at the end of the experiment to calculate the tissue wet-to-dry weight ratio (W/D). The K fc values after reperfusion were significantly higher in the IR group than in the other two groups. Pyruvate concentrations were significantly higher at three time-points in the PEP-IR group than in the other two groups. The W/D was significantly higher in the IR group than in the other two groups. Based on these results, we conclude that the administration of PEP prior to lung ischemia alleviates lung ischemia-reperfusion injury.

Effect of intraoperative acetated Ringer's solution with 1% glucose on glucose and protein metabolism.

PURPOSE: To investigate the effects of the intraoperative administration of Ringer's solution with 1% glucose on the metabolism of glucose, lipid and muscle protein during surgery. METHODS: Thirty-one adult patients, American Society of Anesthesiologists physical status I or II, undergoing elective otorhinolaryngeal, head and neck surgeries were randomly assigned to one of two patient groups: those receiving acetated Ringer's solution with 1% glucose (Group G) or those receiving acetated Ringer's solution without glucose (Group R) throughout the surgical procedure. Plasma glucose was measured at anesthetic induction (T0), artery 1 h (T1), 2 h (T2), 3 h after anesthetic induction (T3) and at the end of surgery (T4). Plasma ketone bodies, insulin and 3-methylhistidine were measured at T0 and T4. RESULTS: The intravenous infusion for patients in Group G and R was 6.1 + or - 0.8 and 6.3 + or - 1.7 ml/kg/h, respectively, with Group G patients receiving a dose of 4.1 g/h glucose. Plasma glucose levels were significantly higher in Group G than in Group R patients at T1, T2, T3 and T4; however, plasma glucose remained <150 mg/dl in both groups. The plasma concentration of ketone bodies was significantly higher (P < 0.05) in Group R than in Group G patients at T4. Changes in plasma 3-methylhistidine concentration was significantly lower in Group G than in Group R patients. These results indicate that acetated Ringer's solution with 1% glucose decreased protein catabolism without hyperglycemia among the Group G patients. CONCLUSION: The infusion of a small dose of glucose (1%) during minor otorhinolaryngeal, head and neck surgeries may suppress protein catabolism without hyperglycemia and hypoglycemia.

Priming with rocuronium or vecuronium prevents remifentanil-mediated muscle rigidity and difficult ventilation.

PURPOSE: The aim of this study was to test our hypothesis that priming with rocuronium would prevent muscle rigidity and difficult ventilation due to remifentanil administration. METHODS: One hundred patients, American Society of Anesthesiologists (ASA) status I or II, were recruited into the study, and randomly allocated to one of four protocols (n = 25 each). Remifentanil was administered at 0.2 microg.kg(-1).min(-1) in group A and at 0.7 microg.kg(-1).min(-1) in groups B, C, and D. Priming with vecuronium (0.02 mg.kg(-1)) or rocuronium (0.06 mg.kg(-1)) was performed at the same time as the infusion of remifentanil in groups C and D, respectively. Anesthesia was induced with 1 mg.kg(-1)propofol 2 min after the start of remifentanil infusion. After the patient had lost consciousness, the anesthesiologist performed mask ventilation, and watched for the presence of muscle rigidity. Ventilation and rigidity were evaluated using a scoring system. RESULTS: Of the 100 patients, 9 were excluded; the number of patients in group A was 24, while groups B and D had 22 patients each, and group C had 23 patients. A lower dose of remifentanil (group A) or priming with vecuronium or rocuronium (groups C, D) significantly reduced the incidence of some difficulty with ventilation (P = 0.0010, P = 0.0053, and P = 0.021, respectively, vs group B). Of the patients in group B, 10 (45.5%) developed some difficulty with ventilation, and ventilation was impossible in 2 of them. On the other hand, 1 (4.1%) of the patients in group A, 2 (8.7%) in group C, and 3 (13.6%) in group D developed some difficulty with ventilation. CONCLUSION: The present study showed that priming with rocuronium or vecuronium reduced the incidence of difficult ventilation by avoiding the muscle rigidity caused by remifentanil.

[Lung protection with anesthetics].

Common inhaled and intravenous anesthetics except the barbiturate are recommended for the patients with bronco-constrictive lung disease because of their bronco-dilating property. However there are pharmacological potency differences between individual anesthetics. The halogenated inhaled anesthetics and propofol exert antiinflammatory effect on acute lung injury and acute respiratory distress syndrome in the laboratory level, but further study is required for future clinical application. These anesthetics also have an organ protective effect on the ischemia reperfusion lung injury, and their clinical application is expected in the lung transplantation surgery.