Effects of different mechanical ventilation methods on respiratory function in elderly patients in the steep Trendelenburg position under general anesthesia / 中华老年医学杂志

Objective:To investigate the effects of different mechanical ventilation methods on respiratory function in elderly patients in the steep Trendelenburg position undergoing general anesthesia.Methods:This was a randomized controlled study.Sixty patients scheduled for elective laparoscopic radical prostatectomy in the steep Trendelenburg position under general anesthesia were randomly divided into the lung protective ventilation strategy group(the P group)and the traditional ventilation strategy group(the T group)(n=30, each group). The setting for the P group included FiO 2 at 50%, tidal volume at 6 ml/kg, respiratory rate at 14-16/min, positive end expiratory pressure(PEEP)at 5 cmH 2O, with sustained lung inflation by pressure control every 30 min and the pressure at 30 cmH 2O for 30 s. The setting for the T group included FiO 2 at 50%, tidal volume at 10 ml/kg, and respiratory rate at 10-12/min.Anesthesia was maintained by sevoflurane, remifentanil and cis-atracurium.Driving pressure(DP), mean airway pressure(P mean)and end-tidal carbon dioxide(EtCO 2)were recorded at T1(5 mins after intubation), T2(after pneumoperitoneum), T3(30 mins after pneumoperitoneum), T4(1h after pneumoperitoneum), T5(2h after pneumoperitoneum), T6(3h after pneumoperitoneum)and T7(end of surgery). Arterial blood partial pressure of carbon dioxide(PaCO 2), alveolar-arterial oxygen partial pressure difference[P(A-a)O 2]and oxygenation index(OI)were recorded at T0(entering the operating room), T1, T3, T4, T5, T6, T8(after extubation)and T9(24h after operation). Arterial-end-tidal carbon dioxide partial pressure difference[P(a-et)CO 2]was recorded at T3, T4, T5 and T6. Results:DP in the P group was lower than in the T group at each time point( P<0.01). The P mean in the P group at each time point was higher than in the T group( P<0.01). EtCO 2 was higher in the P group than in the T group at T1( t=0.751, P<0.01)and T2( t=2.830, P<0.01). PaCO 2 was higher in the P group than in the T group at T1( t=1.435, P<0.01), T3( t=2.469, P<0.01)and T4( t=1.359, P<0.05). There were no statistic differences in P(A-a)O 2, OI and P(a-et)CO 2 between the two groups at any time point( P>0.05). Conclusions:Compared with the traditional ventilation strategy, the lung protective ventilation strategy has lower DP and higher P mean during laparoscopic radical prostatectomy, while it has no advantage in lung oxygenation.The lung protection ventilation strategy can be safely used in laparoscopic radical prostatectomy in the steep Trendelenburg position under general anesthesia.

Efeitos da PEEP na ventilação controlada a volume sobre parâmetros hemodinâmicos em suínos submetidos ao pneumoperitônio associado ao cefalodeclive / Effects of PEEP on hemodynamic variables in pigs submitted to volume-controlled ventilation under pneumoperitoneum associated to cephalodeclive

Videolaparoscopic procedures have gained prominence due to their low invasiveness, causing less surgical trauma and better post-surgical recovery. However, the increase in intra-abdominal pressure due to the institution of pneumoperitoneum can alter the patient's homeostasis. Therefore, volume-controlled ventilation, associated with positive end-expiratory pressure (PEEP), improves arterial oxygenation and prevents pulmonary collapse, but it can lead to important hemodynamic changes. The aim of this study was to evaluate, comparatively, the effects of positive end expiratorypressure (PEEP) on hemodynamic variables of pigs submitted to volume-controlled ventilation, during pneumoperitoneum and maintained in head-down tilt and determine which PEEP value promotes greater stability on hemodynamic variables. Twenty-four pigs were used, between 55 and 65-day-old, weighing between 15 and 25 kg, randomly divided into 3 distinct groups differentiated by positive end-expiratory pressure: PEEP 0 (volume-controlled ventilation and PEEP of 0 cmH2O), PEEP 5 (volume-controlled ventilation and PEEP of 5 cmH2O) and PEEP 10 (volume-controlled ventilation and PEEP of 10 cmH2O). Volume-controlled ventilation was adjusted to 8 mL/kg of tidal volume and a respiratory rate of 25 movements per min. Anesthesia was maintained with continuous infusion of propofol (0.2 mg/kg/min) and midazolam (1 mg/kg/h). Pneumoperitoneum was performed with carbon dioxide (CO2), keeping the intraabdominal pressure at 15 mmHg and the animals were positioned on a 30° head-down tilt. The evaluations of hemodynamic variables started 30 min after induction of anesthesia (M0), followed by measurements at 15-min intervals (from M15 to M90), completing a total of 7 evaluations. The variables of interest were collected over 90 min and submitted to analysis of variance followed by Tukey's post-hoc test, with P < 0.05. The PEEP 10 group had higher values of CVP and mCPP, while the PEEP 5 group, mPAP and PVR were higher. The PEEP 0 group, on the other hand, had higher means of CI. Regarding the moments, there were differences in HR, SAP, DAP, MAP, CO, IC and TPR. According to the literature, important hemodynamic effects due to pneumoperitoneum are reported, which can be caused by the pressure used in abdominal insufflation, CO2 accumulation, duration of the surgical procedure, hydration status and patient positioning. Mechanical ventilation associated with PEEP can also cause an increase in intrathoracic pressure and, therefore, reduce cardiac output. Cardiovascular changes are proportional to the PEEP used. Central venous pressure (PVC) measure the patient's preload, and intrathoracic pressure can interfere with this parameter. The peak pressure values in the PEEP 10 group were higher than the other groups, demonstrating that the increase in intrathoracic pressure results in higher PVC values. Regarding PAPm and PCPm, these variables can be influenced according to the PEEP values and the patient's position. In relation to CI, the increase in PEEP may reflect on intrathoracic pressure, resulting in greater compression of the heart, with a consequent reduction in cardiac output and cardiac index. Therefore, it is concluded that the PEEP effects of 0 cmH2O and 5 cmH2O on hemodynamics are discrete, under the proposed conditions.(AU)

Effects and influencing factors of trendelenburg position on intraocular pressure during robotic-assisted radical cystectomy / 中华护理杂志

Objective To explore the effects of trendelenburg position on intraocular pressure during robotic-assisted radical cystectomy and to analyze its influencing factors.Methods Forty-one patients scheduled for roboticassisted radical cystectomy were included.Perioperative IOP measurements were performed as follows:10 min after anesthesia induction with supine position(T1),10 min after maintaining trendelenburg position(T2),1 h,2 h and 3 h after maintaining Trendelenburg position (T3,T4,T5),10 min after supine position (T6),2 h after supine position(T7).Gender,age,BMI,duration and angle of trendelenburg position,and blood loss were recorded.Results Mean IOP after trendelenburg position was 24.88±2.61 mmHg,which was higher than normal.Mean IOP in Trendelenburg positioning were significantly higher than those at T1,T6,T7,and IOP increased with time.The influencing factors of IOP included duration and degree of Trendelenburg position,and blood loss.Conclusion IOP increased in patients undergoing robotic-assisted radical cystectomy in Trendelenburg position.

Effects and influencing factors of trendelenburg position on intraocular pressure during robotic-assisted radical cystectomy / 中华护理杂志

Objective To explore the effects of trendelenburg position on intraocular pressure during robotic-assisted radical cystectomy and to analyze its influencing factors.Methods Forty-one patients scheduled for roboticassisted radical cystectomy were included.Perioperative IOP measurements were performed as follows:10 min after anesthesia induction with supine position(T1),10 min after maintaining trendelenburg position(T2),1 h,2 h and 3 h after maintaining Trendelenburg position (T3,T4,T5),10 min after supine position (T6),2 h after supine position(T7).Gender,age,BMI,duration and angle of trendelenburg position,and blood loss were recorded.Results Mean IOP after trendelenburg position was 24.88±2.61 mmHg,which was higher than normal.Mean IOP in Trendelenburg positioning were significantly higher than those at T1,T6,T7,and IOP increased with time.The influencing factors of IOP included duration and degree of Trendelenburg position,and blood loss.Conclusion IOP increased in patients undergoing robotic-assisted radical cystectomy in Trendelenburg position.

Ischemia modified albumin: does it change during pneumoperitoneum in robotic prostatectomies?

ABSTRACT Background The unique positioning of the patient at steep Trendelenburg with prolonged and increased intra-abdominal pressure (IAP) during robotic radical prostatectomy may increase the risk of splanchnic ischemia. We aimed to investigate the acute effects of IAP and steep Trendelenburg position on the level of ischemia modified albumin (IMA) and to test if serum IMA levels might be used as a surrogate marker for possible covert ischemia during robotic radical prostatectomies. Patients and Methods Fifty ASA I-II patients scheduled for elective robotic radical prostatectomy were included in this investigation. Exclusion criteria The patients were excluded from the study when an arterial cannulation could not be accomplished, if the case had to be converted to open surgery or if the calculated intraoperative bleeding exceeded 300ml. All the patients were placed in steep (45 degrees) Trendelenburg position following trocar placement. Throughout the operation the IAP was maintained between 11-14mmHg. Mean arterial blood pressure (MAP), cardiac output (CO) were continuously monitored before the induction and throughout the surgery. Blood gases, electrolytes, urea, creatinine, alanine transferase (ALT), aspartate transferase (AST) were recorded. Additionally, IMA levels were measured before, during and after surgery. Results (1) MAP, CO, lactate and hemoglobin (Hb) did not significantly change in any period of surgery (p>0.05); (2) sodium (p<0.01), potassium (p<0.05) and urea (p<0.05) levels decreased at postoperative period, and no significant changes at creatinine, AST, ALT levels were observed in these patients; (3) At the end of surgery (180 min) pCO2, pO2, HCO3 and BE did not change compared to after induction values (p>0.05) but mild acidosis was present in these patients (p<0.01 vs. after induction); (4) IMA levels were found to be comparable before induction (0.34±0.04), after induction (0.31±0.06) ...

Increased amount of pleural effusion during head-down tilt position in ovarian cancer patient with ascites: A case report

Pseudo-Meigs syndrome is accompanied with pleural effusion, ascites and a benign or malignant tumor of ovary, tubes, uterus, round ligament or colon. We reported a case of hypoxia in an ovarian cancer patient with moderate ascites after head-down tilt position for central venous catheterization under general anesthesia. Massive pleural effusion was detected on portable chest X-ray, which was not observed in a preoperative radiologic test. The patient had no respiratory symptoms and breath sound was normal in both lungs prior to surgery. The pleural effusion was resolved by a chest tube insertion.

Effects of different head-down tilt angles on respiratory mechanics and cerebral circulation during laparoscopic radical resection of rectal carcinoma / 中华麻醉学杂志

Objective To evaluate the effects of different head-down tilt (HDT) angles on respiratory mechanics and cerebral circulation during laparoscopic radical resection of rectal carcinoma in the patients.Methods Thirty patients of both sexes,aged 40-64 yr,of ASA physical status Ⅰ or Ⅱ,with body mass index ＜ 30 kg/m2,scheduled for elective laparoscopic radical resection of rectal carcinoma,were included in the study.Anesthesia was induced with midazolam,fentanyl,propofol and cis-atracurium and maintained with targetcontrolled infusion of propofol and remifentanil and cis-atracurium when needed.At 5 min after supine position,5 min after 30° HDT,5 min after 35° HDT,5 min after 40° HDT,and 30 min after pneumoperitoneum (T1-5),airway pressure (Paw),peak airway pressure (PIP),lung compliance (Cpat) and jugular bulb blood pressure (JBP) were recorded.Blood samples were taken from the radial artery and jugular bulb for blood gas analysis and arterial partial pressure of oxygen (PaO2),partial pressure of carbon dioxide in artery (PaCO2),arterial oxygen saturation (SaO2),jugular bulb oxygen partial pressure (PjvO2),and jugular bulb venous saturation (SjvO2) were recorded at each time point mentioned above.Results Paw,PIP,MAP,PaCO2,JBP,PjvO2 and SjvO2 were significantly increased as compared with those obtained when the patients were in supine position,increased gradually with the increasing HDT angles,and decreased to the level obtained when the patients were in supine position at 30 min after pneumoperitoneum.Cpat and PaO2 were significantly decreased as compared with those obtained when the patients were in supine position decreased gradually with the decreasing HDT angles,and increased to the level obtained when the patients were in supine position at 30 min after pneumoperitoneum.Conclusion HDT-induced effects on respiratory mechanics and cerebral circulation increase with increasing angles during laparoscopic radical resection of rectal carcinoma; thus the optimum HDT angle is smaller than 40° for the patients undergoing this kind of surgery.

Effect of 72h weightlessness simulation on processing speed of mental rotation of males / 中华行为医学与脑科学杂志

Objective To explore the effect of weightlessness simulation on processing speed of mental rotation of males in 72 h head-down tilt,in order to further reveal human performance changes caused by weightlessness.Methods During 72 h weightlessness simulation (9 am day 1 to 9 pm day 4,head-down tilt started from 9 pm day 1),16 male subjects were processed speed of rotation data byhand picture mental rotation (test 8 times),using self cross-references design,and the variation of processing speed of mental rotation by duration was analyzed.Results The linear regression analysis showed,the reaction time of each time point for each subject as the independent variable,the angle of rotation as the dependent variable,with the extension of simulated weightlessness time.The intercept(constant term of the regression equation),indicating the processing speed of non-rotation,were gradually increased with HDT time,but didn(t) reached significantly difference (F(3,14) =0.551,P =0.650) ;the slope(Regression coefficient of the regression equation),indicating the processing speed of rotation.were gradually increased with HDT time,and reached the significantly difference (F(3,14) =4.338,P =0.009).The value of intercept and slope was like upside-down U in three days,and reached the highest value at day 2.Conclusion Weightlessness simulation have affection on the speed of mental rotation,especially on the rotation speed.

Severe brachial plexus injury after retropubic radical prostatectomy: A case report / 대한마취과학회지

A 69-year-old man with prostate cancer underwent surgery for 16 h. Approximately 6 h after surgery, the patient developed severe pain and motor weakness in his right arm. After neurologic examinations that included a nerve conduction study and electromyography, the patient was diagnosed with a brachial plexus injury. The causes of the brachial plexus injury were thought to be abduction of both arms, direct compression of the shoulder brace, and prolonged surgery. Most of the postoperative peripheral nerve injuries due to patient position are preventable, and anesthetists and surgeons should be very careful in positioning the patient accurately.

The effects of sevoflurane and propofol anesthesia on cerebral oxygenation in gynecological laparoscopic surgery / 대한마취과학회지

BACKGROUND: Both the Trendelenburg position and pneumoperitoneum with carbon dioxide have been reported to increase intracranial pressure (ICP) and to alter cerebral blood flow or cerebral blood volume. Also anesthetic agents have variable effects on cerebral hemodynamics and ICP. The present study was conducted to determine whether regional cerebral oxygen saturation (rSO2) values differ between propofol and sevoflurane anesthesia during laparoscopic surgery in the Trendelenburg position. METHODS: Thirty-two adult women undergoing gynecological laparoscopic surgery were divided into sevoflurane and propofol groups. rSO2 values were recorded at 10 min after induction in the neutral position (Tpre), 10 min after the pneumoperitoneum in the Trendelenburg position (Tpt) and 10 min after desufflation in the neutral position (Tpost). For analysis of rSO2, we did ANOVA and univariate two-way ANCOVA with covariates being mean arterial pressure and end tidal carbon dioxide tension. RESULTS: Between sevoflurane and propofol groups, the change in rSO2 was significantly different even after ANCOVA. rSO2 at Tpt (76.3 +/- 5.9% in sevoflurane vs 69.4 +/- 5.8% in propofol) and Tpost (69.5 +/- 7.1% in sevoflurane vs 63.8 +/- 6.6% in propofol) were significantly higher in the sevoflurane group compared with the propofol group. In the propofol group, rSO2 at Tpost was significantly lower than at Tpre (71.1 +/- 4.8%) and cerebral oxygen desaturation occurred in two patients (14.3%). CONCLUSIONS: Significantly lower rSO2 values were observed in the propofol group during gynecological laparoscopic surgery. The possibility of cerebral oxygen desaturation should not be overlooked during propofol anesthesia even after desufflation of the abdomen in the neutral position.

The influence of head down tilt on electroretinography / 眼科研究

Background Influence of weightlessness on visual function has been a hot topic in aerospace medicine field.Electroretinography (ERG) is valuable tool of evaluating visual function.Objective This study aims to observe the influence of head down tilt simulated weightlessness on ERG.MethodHead down tilt for 6° was adopted in 6 healthy volunteers.Flash ERG,including rod response,maxium response,cone response,oscillatory potentials (OPs) and 30 Hz flicker was recorded,and the latency and amplitude from each wave were analyzed before,two days and five days after trial.The record procedure followed the ISCEV standard for full field clinical electroretinography (2008 update).Oral informed consent was obtained from all the subjects prior to the trail.Results No significant differences were detected in the latencies and amplitudes of a,b waves of cone response and 30 Hz flicker among various time points(P＞0.05).The latencies were significantly prolonged in b wave of rod and a,b waves of maxim responses(P＜0.01),but no obvious change was found in amplitudes (P＞0.05).Both the latency and amplitude of all of the wavelets of OPs were considerably among the different time points(P＜0.05-0.01),and the ∑OPs was evidently different among the different time points(P＜0.05).Conclusion Head down tilt simulated weightlessness induce the abnormality of visual function in the early stage.

The effect of pneumoperitoneum and Trendelenburg position on respiratory mechanics during pelviscopic surgery / 대한마취과학회지

BACKGROUND: Conventional pelviscopic surgery requires pneumoperitoneum with CO2 gas insufflation and lithotomy-Trendelenburg position. Pneumoperitoneum and Trendelenburg position may influence intraoperative respiratory mechanics in anesthetic management. This study was conducted to investigate the influence of pneumoperitoneum and Trendelenburg position on respiratory compliance and ventilation pressure. METHODS: Twenty-five patients scheduled for elective gynecologic laparoscopy were evaluated. The patients had no preexisting lung or heart disease or pathologic lung function. Conventional general anesthesia with thiopental sodium, lidocaine, rocuronium, and sevoflurane was administered. The peak inspiratory pressure, plateau pressure, and end-tidal CO2 were measured before and after creation of pneumoperitoneum with an intraabdominal pressure of 12 mmHg, then after 10 minutes and 30 minutes in the 20degrees Trendelenburg position, and after deflation of pneumoperitoneum. The dynamic lung compliance was then calculated. RESULTS: Following creation of pneumoperitoneum, there was a significant increase in peak inspiratory pressure (6 cmH2O), plateau pressure (7 cmH2O), and end-tidal CO2 (5 mmHg), while dynamic lung compliance decreased by 12 ml/cmH2O. Overall, the Trendelenburg position induced no significant hemodynamic or pulmonary changes. CONCLUSIONS: The effects of pneumoperitoneum significantly reduced dynamic lung compliance and increased peak inspiratory and plateau pressures. The Tredelenburg position did not change these parameters.

The Influence of Head-down Tilt on the Visual Evoked Potential of Healthy People / 航天医学与医学工程

Objective To observe the influence of head-down tilt on visual evoked potential.Methods Six healthy volunteers were exposed to-6? head-down tilt.The visual evoked potential were measured before the test,the second day and the fifth day of the test under different space frequency.Results No significant difference was found in the latency of P100 before and after the test.The amplitude of P100 had significant change under high space frequency.But not the same happened on middle and low space frequency.Conclusion head-down tilt can induce the change of visual evoked potential under high space frequency,which means the weightlessness may influent the visual function.

Difference of Responses of Males and Females under-30? Head-down Tilt / 航天医学与医学工程

Objective To find out the difference of responses to HDT between females and males of different occupations.Methods Healthy female employees(group A,n=11)and female pilots(group B,n=10)and male special pilots(group C,n=14)and male employees(group D,n=7)were tested with-30? head-down tilt for 45 min.Results Heart rate(HR)of females and males all decreased with time during HDT,especially male employees group and female pilots group(P

The Effects of Intraperitoneal Carbon Dioxide Insufflation and Head-down Tilt Position on Intracranial Pressure / 대한마취과학회지

BACKGROUND: The laparoscopy requires CO2 insufflation and posture changes for operational convenience. However, above circumstances affect the cardiopulmonary systems significantly. And then intracranial pressure (ICP) may be also influenced. METHODS: To ascertain the changes of ICP, an experimental study was performed, in which the parameters of hemodynamic status, arterial blood gas components and ICP were measured from twelve cases of Korean mongrel dogs. Pneumoperitoneum was produced by CO2 insufflation(15 mmHg) and then posture was altered from horizontal to head-down tilt of 20, 30 and 40 degree*. The measurements were obtained before (control), after CO2 insufflated horizontal position at 20, 40 and 60 minute in CO2 insufflated tilt** and CO2 deflated horizontal***. RESULTS: MAP and HR were not related to the insufflated time and degree of tilt. CVP and PCWP were significantly increased after CO2 insufflated tilt (p<0.01), but returned to control after deflated supine. PaCO2 was not significantly changed after CO2 insufflated supine, but grdually increased with degree of tilt and time (p<0.01). ICP was increased at 40 and 60 minute of 20degree, and at 20 minute of 30degree(p<0.05), then markedly increased at 40 and 60 minute of 30degree, and at 20, 40 and 60 minute of 40degreetilt (p<0.01). The increment of ICP was parallel with time and degree of tilt. But, ICP was returned to control after deflated supine. CONCLUSIONS: ICP was increased significantly during laparoscopy in head-down tilt, although it was reversible. Therefore, the patient must be given special attention during laparoscopy in whom the increment of ICP may be harmful.