Effect of hypercapnia on arterial hypotension after induction of anaesthesia

We evaluated the effectiveness of intentional hypercapnia against hypotension after induction of anaesthesia with thiopental and isoflurane (TI) or propofol (P). For each group, 24 patients were anaesthetized with thiopental 4 mg kg(-1) (TI) or propofol 2 mg kg(-1) (P) for tracheal intubation and then lightly anaesthetized with isoflurane at 0.6% end-expiratory concentration (TI) or by 6 mg kg(-1) h(-1) infusion of propofol (P). In both anaesthesia groups, patients were randomly assigned to either normocapnia (end-tidal CO(2) = 35 mmHg) or hypercapnia (end-tidal CO(2) = 45 mmHg), which were achieved through adjusting the tidal volume. Systolic arterial pressure (SAP) 15 min after intubation was compared with the preanaesthetic baseline value. Under normocapnia, both TI and P induced a comparable, statistically significant suppression of SAP by approximately 20 mmHg from baseline. Hypercapnia prevented the decrease in SAP in TI but not in P. No patient in the TI-hypercapnia group experienced SAP below 100 mmHg, unlike those in the other groups. In conclusion, mild hypercapnia was effective in the prevention of hypotension in patients receiving thiopental followed by 0.6% end-expiratory isoflurane, but not in patients receiving 6 mg kg(-1) h(-1) propofol.     

A randomised controlled feasibility trial of a clinical protocol to manage hypotension during major non-cardiac surgery

Intra-operative hypotension is a risk factor for postoperative morbidity and mortality. Minimally invasive monitors that derive other haemodynamic parameters, such as stroke volume, may better inform the management of hypotension. As a prelude to a multicentre randomised controlled trial, we conducted a single-centre feasibility trial of a protocol to treat hypotension as informed by minimally invasive haemodynamic monitoring during non-cardiac surgery. We recruited adults aged ≥40 years with cardiovascular risk factors who underwent non-cardiac surgery requiring invasive arterial pressure monitoring. Participants were randomly allocated to usual care, or a clinical protocol informed by an arterial waveform contour analysis monitor. Participants, outcome assessors, clinicians outside operating theatres and analysts were blinded to treatment allocation. Feasibility was evaluated based on: consent rate; recruitment rate; structured feedback from anaesthesia providers; and between-group differences in blood pressure, processes-of-care and outcomes. The consent rate among eligible patients was 33%, with 30 participants randomly allocated to the protocol and 30 to usual care. Anaesthesia providers rated the protocol to be feasible and acceptable. The protocol was associated with reduced fluid balance and hypotension exposure in the peri-operative setting. Postoperative complications included: acute myocardial injury in 18 (30%); acute kidney injury in 17 (28%); and surgical site infection in 7 (12%). The severity of complications was rated as moderate or severe in 25 (42%) participants. In summary, this single-centre study confirmed the feasibility of a multicentre trial to assess the efficacy and safety of a physiologically guided treatment protocol for intra-operative hypotension based on minimally invasive haemodynamic monitors.     

Assessment of refill and hypovolaemia by continuous surveillance of blood volume and extracellular fluid volume

During renal replacement therapy hypovolaemia due to ultrafiltration(UF) may, when not sufficiently counteracted by refill fromthe interstitium, result in hypotension. Combining two recentlydeveloped methods the haemodynamic process of refill was studiedin order to find characteristics featuring hypotension. Relativeblood volume (BV) and extracellular fluid volume (EFV) weremeasured continuously in 40 stable haemodialysis patients bymeans of an optical and a conductivity technique respectively.Regarding their postdialytic (PD) EFV the patients were dividedinto three groups: normohydrated (N, n=20), dehydrated (D, n=11) and overhydrated (O, n=9). Significant differences betweenthe groups were assessed in BV decrease (after 2 h until theend of treatment P<0.05 and after 3 h P<0.01), EFV decrease(after 3 h P<0.05) and occurrence of hypotensive episodes(N,5; D,7; O,none; P<0.01). During the entire session thespeed of BV decrease was significantly higher in hypotensivepatients (H) than in non-hypotensive patients (non-H). At themoment of hypotension (after 141±49 min) residual BVwas less (P<0.0005) in H (87.7±5.2%) than at the correspondingmoment in non-H patients (96.5±4.0%). PD BV and PD EFV,both expressed as a percentage of the starting value, correlatedsignificantly (r=0.63, p<0.005) and UF-volume (differencesbetween the groups were not significant) correlated to EFV decrease(r=0.45, P<0.005). In conclusion, the combination of bothnon-invasive methods elucidates the pathophysiology of UF-inducedhypotension and provides a means of reducing dialysis morbidity.The influence of tissue hydration state on these variables hasbeen shown.     

The effect of prophylactic metaraminol on systemic hypotension caused by induction of anaesthesia with propofol in patients over 55 years old

We conducted a double-blind, randomised, placebo-controlled study evaluating the efficacy of prophylactic metaraminol for preventing propofol-induced hypotension. Thirty patients aged 55-75 years undergoing general anaesthesia were randomly allocated to receive either metaraminol 0.5 mg or saline before administration of fentanyl 1 microg.kg(-1) and propofol 2 mg.kg(-1). Induction of anaesthesia was associated with a decrease in mean and systolic arterial pressure in both groups (p = 0.0001). However, there was no significant difference between the two groups. These results show that prophylactic use of metaraminol 0.5 mg does not prevent the decrease in blood pressure following fentanyl and propofol induction in older patients.     

The effect of intra-operative hypotension on acute kidney injury,postoperative mortality and length of stay following emergency hip fracture surgery

The association between intra-operative hypotension and postoperative acute kidney injury, mortality and length of stay has not been comprehensively evaluated in a large single-centre hip fracture population. We analysed electronic anaesthesia records of 1063 patients undergoing unilateral hip fracture surgery, collected from 2015 to 2018. Acute kidney injury, 3-, 30- and 365-day mortality and length of stay were evaluated to assess the relationship between intra-operative hypotension absolute values (≤ 55, 60, 65, 70 and 75 mmHg) and duration of hypotension. The rate of acute kidney injury was 23.7%, mortality at 3-, 30- and 365 days was 3.7%, 8.0% and 25.3%, respectively, and median (IQR [range]) length of stay 8 (6–12 [0–99]) days. Median (IQR [range]) time ≤ MAP 55, 60, 65, 70 and 75 mmHg was 0 (0–0.5[0–72.1]); 0 (0–4.4 [0–104.9]); 2.2 (0–8.7 [0–144.2]); 6.6 (2.2–19.7 [0–198.8]); 17.5 (6.6–37.1 [0–216.3]) minutes, and percentage of surgery time below these thresholds was 1%, 2.5%, 7.9%, 12% and 21% respectively. There were some univariate associations between hypotension and mortality; however, these were no longer evident in multivariable analysis. Multivariable analysis found no association between hypotension and acute kidney injury. Acute kidney injury was associated with male sex, antihypertensive medications and cardiac/renal comorbidities. Three-day mortality was associated with delay to surgery ? 48 hours, whilst 30-day and 365-day mortality was associated with delay to surgery ≥ 48 hours, impaired cognition and cardiac/renal comorbidities. While the rate of acute kidney injury was similar to other studies, use of vasopressors and fluids to reduce the time spent at hypotensive levels failed to reduce this complication. Intra-operative hypotension at the levels observed in this cohort may not be an important determinant of acute kidney injury, postoperative mortality and length of stay.     

Prevention of arterial hypotension after spinal anaesthesia using vena cava ultrasound to guide fluid management

Background

Significant hypotension is frequent after spinal anaesthesia and fluid administration as therapy is usually empirical. Inferior vena cava (IVC) ultrasound (US) is effective to assess fluid responsiveness in critical care patients. The aim of this study was to evaluate the IVCUS-guided volume optimization to prevent post-spinal hypotension.

使用硝酸甘油控制性降压对食管癌开胸术后胸腔引流量的影响

目的观察食管癌根治术后应用硝酸甘油控制性降压对术后胸腔引流量及胸腔引流管拔除时间的影响。 方法将甘肃省人民医院胸外科2015年3月—2017年4月行经左胸食管癌根治术的128例患者随机分为两组。试验组(n＝64)：术后48 h内以0.01%的硝酸甘油溶液微量泵泵入行控制性降压,血压严格控制在90～100 mmHg/60～70 mmHg范围内;对照组(n＝64)：术后48 h内未行硝酸甘油控制性降压,血压波动在110～148 mmHg/70～102 mmHg。比较两组患者的术前临床资料,以及术后第1、3、5、7、9天的胸腔引流量及胸腔引流总量、术后胸腔引流管拔除时间。 结果两组患者的年龄、性别、病变部位、病理类型及TNM分期等临床资料比较差异均无统计学意义(P>0.05)。试验组患者的术后胸腔引流总量、胸腔引流管拔除时间和住院时间均显著少于对照组,差异有统计学意义[(939±134)ml vs (1 203±146)ml,P<0.01;(8.7±1.1)d vs (10.6±1.3)d,P<0.01;(9.5±1.2)d vs(11.2±2.4)d]。 结论经左胸食管癌根治术后应用硝酸甘油控制性降压可有效减少胸腔引流总量,能在一定程度上缩短胸腔引流管的拔除时间和住院时间。     

胸椎管狭窄症术后脑脊液漏继发低颅压症状的临床特点及处理策略

【摘要】 目的：探讨胸椎管狭窄症术后脑脊液漏继发低颅压症状的临床特点及处理策略。方法：回顾性分析2021年8月～2022年3月于北京大学第三医院骨科行胸椎后路手术且术后并发脑脊液漏的38例胸椎管狭窄症患者的资料,其中男7例,女31例,年龄30～78岁（56.6±11.1岁）。根据术后是否出现低颅压症状分为低颅压症状组和非低颅压症状组,低颅压症状组15例,男1例,女14例,年龄43～78岁（58.9±11.0岁）,非低颅压症状组23例,男6例,女17例,年龄30～72岁（55.1±11.2岁）。采用疼痛视觉模拟评分（visual analogue scale,VAS）评估头痛,按照WHO规定标准对恶心呕吐进行分级,头晕按患者的主观感受分为：轻度、中度和重度,对比两组患者的手术时间、术中出血量、术后补液量及引流量;采用二元Logistic分析低颅压症状的危险因素;总结低颅压症状的具体表现、严重程度、出现时间、持续时间;评价补液、调整体位、改变引流方式等治疗措施对低颅压症状的疗效。结果：15例出现低颅压症状的患者中,头痛11例（73.3%）,恶心呕吐9例（60.0%）,头晕5例（33.3%）,其中7例（46.7%）为单一症状,6例（40.0%）合并2种症状,2例（13.3%）合并3种症状。头痛VAS评分为2～6分（4.0±1.0分）,恶心呕吐程度：Ⅱ级1例,Ⅲ级7例,Ⅳ级1例,头晕程度均为轻度。患者出现低颅压症状时间为术后24～96h（41.3±25.5h）。低颅压症状持续天数为1～4d（2.2±0.9d）。低颅压症状治疗方法包括补液、调整体位及改变引流方式,拔除引流管时间为3～5d,平均为3.9d。15例患者低颅压症状经保守治疗后均完全缓解,顺利出院。脑脊液漏继发并发症情况,非低颅压症状组颅内出血1例、蛛网膜下腔-胸膜腔瘘1例,低颅压症状组伤口裂开1例。患者胸椎管狭窄症术后并发脑脊液漏患者出现低颅压症状比例为39.5%（15/38）,低颅压症状组和非低颅压症状组在手术时间、术中出血量、术后补液量及引流量无统计学差异（P＞0.05）。Logistic回归分析显示年龄、性别、体重、身高、BMI、手术时间、手术节段、术中总入量、术中总出量、术中出血量、术后第1天血钠、平均每日引流量、平均每日引流量/体重、平均每日补液量、平均每日补液量/体重与低颅压症状无显著相关性（P＞0.05）。结论：胸椎管狭窄症术后并发脑脊液漏患者出现低颅压症状的比例较高;低颅压症状的常见临床表现为头痛、恶心呕吐、头晕,半数患者会合并出现两种或两种以上症状;补液、调整体位及改变引流方式等综合处理方案能够有效地缓解低颅压症状或缩短其持续时间。     

The role of plasma volume and fluid overload in the tolerance to ultrafiltration and hypotension in hemodialysis patients

IntroductionUltrafiltration (UF) in hemodialysis (HD) patients is accompanied by irregular falls in plasma volume (PV) and blood pressure (BP).MethodsWe obtained in 321 patients (large cohort), body weight (BW), BP, samples of blood to determine hemoglobin (Hb) and hematocrit (Ht), Pre and Post HD. We estimated the % variation of the PV and its effect on the BP. In a small cohort of 38/321 patients, arterial blood was drawn Pre and Post HD and at 2, 48, and 72 h to determined Hb and Ht and % variation of the PV. Bio-impedance spectroscopy (BIS) was performed, in the same times, to estimate: dry weight (DW), total body water (TBW), extracellular water (ECW), Fluid overload (FO) and phase angle (PhA).ResultsWe divided our large cohort in two groups. The Hypotensive group with a fall equal or more than 20 mmHg (96/321,30%) and Normotensive group with a drop equal or less than 19 mmHg (225/321,70%). The UF was 2.73 ± 0.72 L in the Hypotensive group and 2.53 ± 0.85 L in the Normotensive group (p < 0.0001). The % PV was −11.7 ± 17.8 in the Hypotensive group and −8.53 ± 10.07 in the Normotensive group (p < 0.0001). The systolic blood pressure (SBP) correlated with the % change of the PV (r = -0.232; p < 0.0001). The FO was contrasted with the % of water removed by UF (r = -0.890; p < 0.0001).ConclusionThe SBP drop was secondary to the fall in the PV after UF. The FO was irregular and modulates in part the fall in the SBP.     

Noninvasive continuous detection of arterial hypotension during induction of anaesthesia using a photoplethysmographic signal: proof of concept

Background

During general anaesthesia, intraoperative hypotension (IOH), defined as a mean arterial pressure (MAP) reduction of > 20%, is frequent and may lead to complications. Pulse oximetry is mandatory in the operating room, making the photoplethysmographic signal and parameters, such as relative dicrotic notch height (Dic_pleth) or perfusion index (PI), readily available. The purpose of this study was to investigate whether relative variations of Dic_pleth and PI could detect IOH during anaesthesia induction, and to follow their variations during vasopressor boluses.

Prevention of hypotension after spinal anaesthesia for caesarean section: a systematic review and network meta-analysis of randomised controlled trials

Spinal anaesthesia for caesarean section commonly causes maternal hypotension. This systematic review and network meta-analysis compared methods to prevent hypotension in women receiving spinal anaesthesia for caesarean section. We selected randomised controlled trials that compared an intervention to prevent hypotension with another intervention or inactive control by searching MEDLINE and Embase, Web of Science to December 2018. There was no language restriction. Two reviewers extracted data on trial characteristics, methods and outcomes. We assessed risk of bias for individual trials (Cochrane tool) and quality of evidence (GRADE checklist). We assessed 109 trials (8561 women) and 12 different methods that resulted in 30 direct comparisons. Methods ranked by OR (95%CI) from most effective to least effective were: metaraminol 0.11 (0.04–0.26); norepinephrine 0.13 (0.06–0.28); phenylephrine 0.18 (0.11–0.29); leg compression 0.25 (0.14–0.43); ephedrine 0.28 (0.18–0.43); colloid given before induction of anaesthesia 0.38 (0.24–0.61); angiotensin 2, 0.12 (0.02–0.75); colloid given after induction of anaesthesia 0.52 (0.30–0.90); mephentermine 0.09 (0.01–1.30); crystalloid given after induction of anaesthesia 0.78 (0.46–1.31); and crystalloid given before induction of anaesthesia 1.16 (0.76–1.79). Phenylephrine caused maternal bradycardia compared with control, OR (95%CI) 0.23 (0.07–0.79). Ephedrine lowered umbilical artery pH more than phenylephrine, standardised mean difference (95%CI) 0.78 (0.47–1.49). We conclude that vasopressors should be given to healthy women to prevent hypotension during caesarean section with spinal anaesthesia.     

Effect of induced hypotension on serum concentrations of atropine after intramuscular administration

The serum concentrations of atropine after a single intramuscular injection of 0.01 mg/kg were determined by radioimmunoassay in nine general surgical patients during and after a combination anaesthesia and compared with those of 13 neurosurgical patients operated on during induced hypotensive anaesthesia (sodium nitroprusside plus trimetaphan). Surprisingly, comparable serum levels were found in both patient groups. We conclude that this kind of induced hypotension cannot be used as a model of drug absorption in such clinical situations as cardiac failure, haemorrhage or anaphylactic drug reactions.     

Effect of pneumatic leg compression on post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy: a double-blind randomised controlled trial

Post-induction hypotension is common and associated with postoperative complications. We hypothesised that pneumatic leg compression reduces post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy. In this double-blind randomised study, patients were allocated randomly to the pneumatic leg compression group (n = 50) or control (n = 50). In the intervention group, pneumatic leg compression was initiated before induction of anaesthesia. In the control group, pneumatic leg compression was initiated 20 min after anaesthesia induction. The primary outcome was the incidence of post-induction hypotension in these groups. Post-induction hypotension was defined as systolic blood pressure < 90 mmHg during the first 20 min after induction. Haemodynamic variables and area under the curve of post-induction systolic blood pressure over time were assessed. Complications associated with pneumatic leg compression were recorded, including: peripheral neuropathy; compartment syndrome; extensive bullae beneath the leg sleeves; and pulmonary thromboembolism. The incidence of post-induction hypotension decreased in the pneumatic leg compression group compared with that in the control group; 5 (10%) vs. 29 (58%), respectively, p < 0.001. In the pneumatic leg compression group, the lowest systolic, diastolic and mean blood pressures 20 min after induction of anaesthesia were significantly greater than the control group. Pneumatic leg compression resulted in an increased area under the curve of systolic blood pressure in the first 20 min after induction, p = 0.001. There were no pneumatic leg compression-related complications. Pneumatic leg compression reduced post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy, suggesting that it is an effective and safe intervention to prevent post-induction hypotension among elderly patients undergoing general anaesthesia.     

尼卡地平控制性降压对家犬脊髓诱发电位的影响

目的观察尼卡地平控制性降压对家犬脊髓诱发电位（SCEPs）的影响,探讨脊柱手术麻醉中尼卡地平控制性降压的安全性。方法成年杂种犬6只,体重12．0～15．5kg,用2．5o,4硫喷妥钠行麻醉诱导并维持麻醉。股动脉置管监测MAP。以尼卡地平8μg·kg^-1·min^-1持续静脉注射进行控制性降压,降压标准为基础MAP的40％。以日本光电诱发电位监测仪测定SCEPs。结果MAP平均下降幅度为42．9％,控制性降压后体感诱发电位（SEP）波幅及运动诱发电位（MEP）波幅差异无统计学意义。结论尼卡地平控制性降压对SCEPs影响较小,可安全用于脊髓手术。     

血液稀释对控制性降压下血清胱抑素C的影响

目的探讨急性等容性血液稀释对控制性降压期间血清胱抑素（Cys-C）的影响。方法选择40例择期脊柱手术病人,随机分为4组,对照组、控制性降压组、血液稀释组和血液稀释联合控制性降压组,每组10例。用0.01%硝普钠进行控制性降压,将MAP维持在60～70mmHg;通过静脉采血和输液进行血液稀释,将Hct降至25%～30%;测定Cys-C含量。结果控制性降压组Cys-C含量明显升高（P〈0.05）。结论单纯控制性低血压可使肾小球滤过率（GFR）降低,而联用血液稀释则对肾功能有保护作用。     

Effect of thoracic epidural anaesthesia on ventilation= perfusion distribution and intrathoracic blood volume before and after induction of general anaesthesia

Background: Gas exchange is impaired during general anaesthesia due to development of shunt and ventilation-perfusion mismatching. Thoracic epidural anaesthesia (TEA) may affect the mechanics of the respiratory system, intrathoracic blood volume and possibly ventilation-perfusion (V_A/Q) distribution during general anaesthesia.
Methods: V_A/Q relationships were analyzed in 24 patients undergoing major abdominal surgery. Intrapulmonary shunt (Qs/ Q_T), perfusion of "low" V_A/Q areas, ventilation of "high V_A/ regions, dead space ventilation and mean distribution of ventilation and perfusion were calculated from the retention/excretion data of six inert gases. Intrathoracic blood volume (ITBV) and pulmonary blood volume (PBV) were determined with a double indicator technique. Recordings were made before and after administration of 8.5±1.5 ml bupivacaine 0.5% (n=12) or 8.3±1.8 ml placebo (n=12) into a thoracic epidural catheter and after induction of general anaesthesia.
Results: Before TEA, QS/QT was normal in the bupivacaine group (222%) and the placebo group (23%). TEA covering the dermatomal segments T 12 to T 4 had no effect on V_A/Q relationships, ITBV and PBV. After induction of general anaesthesia S/T increased to 84% (bupivacaine group, P < 0.05) and to 72% (placebo group, P < 0.05). ITBV and PBV decreased significantly to the same extent in the bupivacaine group and the placebo group.
Conclusions: TEA has no effect on V_A/Q distribution, gas exchange and intrathoracic blood volume in the awake state and does not influence development of S/T and V_A/Q inequality after induction of general anaesthesia.     

The association of hypotension during non‐cardiac surgery,before and after skin incision,with postoperative acute kidney injury: a retrospective cohort analysis

Intra‐operative hypotension is associated with acute postoperative kidney injury. It is unclear how much hypotension occurs before skin incision compared with after, or whether hypotension in these two periods is similarly associated with postoperative kidney injury. We analysed the association of mean arterial pressure < 65 mmHg with postoperative kidney injury in 42,825 patients who were anaesthetised for elective non‐cardiac surgery. Intra‐operative hypotension occurred in 30,423 (71%) patients: 22,569 (53%) patients before skin incision; and 24,102 (56%) patients after incision. Anaesthetised patients who were hypotensive had mean arterial pressures < 65 mmHg for a median (IQR [range]) of 5.5 (0.0–14.7 [0.0–60.0]) min.h^?1 before skin incision, compared with 1.7 [0.3–5.1 [0.0–57.5]) min.h^?1 after incision: a median (IQR [range]) of 36% (0%–84% [0%–100%]) of hypotensive readings were before incision. We diagnosed postoperative kidney injury in 2328 (5%) patients. The odds ratio (95%CI) for acute kidney injury was 1.05 (1.02–1.07) for each doubling of the duration of hypotension, p < 0.001. Postoperative kidney injury was associated with the product of hypotension duration and severity, that is, area under the curve, before skin incision and after, odds ratio (95%CI): 1.02 (1.01–1.04), p = 0.004; and 1.02 (1.00–1.04), p = 0.016, respectively. A substantial fraction of all hypotension happened before surgical incision and was thus completely due to anaesthetic management. We recommend that anaesthetists should avoid mean arterial pressure < 65 mmHg during surgery, especially after induction, assuming that its association with postoperative kidney injury is, at least in part, causal.     

尼卡地平控制性降压对家犬脊髓血流的影响

目的　观察尼卡地平控制性降压对家犬脊髓血流的影响。方法　成年杂种犬 6只 ,体重 12 5～ 16kg ,以 2 5 %硫喷妥钠麻醉。股动脉置管监测MAP。以尼卡地平 8μg·kg 1·min 1持续静脉注射控制性降压。以激光多普勒血流仪测定脊髓血流 (SCBF)。结果　降压前MAP为 (12 5 7±10 6 )mmHg ,降压后为 (72 0± 11 2 )mmHg ,平均下降 4 2 8%。降压前SCBF为 (9 80± 1 0 5 )v ,降压后为 (8 0 4± 0 96 )v ,降低幅度为 18%。结论　尼卡地平控制性降压对SCBF影响较小 ,可安全用于脊髓手术。