滴定个体化呼气末正压对全麻俯卧位脊柱手术老年患者呼吸功能的影响

目的探讨滴定个体化呼气末正压(PEEP)对全麻俯卧位脊柱手术老年患者术中呼吸和循环的影响。方法选择择期全麻下行俯卧位脊柱手术老年患者80例,男39例,女41例,年龄≥65岁,ASAⅡ或Ⅲ级。根据术中是否滴定获取个体化PEEP将患者随机分为两组:滴定组和对照组,每组40例。滴定组从0 cmH_2O开始递增至20 cmH_2O,PEEP变化梯度为2 cmH_2O获取个体化PEEP;对照组PEEP恒定为5 cmH_2O并通气至手术结束。记录滴定过程中每个PEEP水平持续1 min时动态肺顺应性(Cdyn),将Cdyn最大时的PEEP定为个体化PEEP。记录俯卧位时(T_0)、PEEP通气10 min(T_1)、30 min(T_2)、60 min(T_3)、手术结束(T_4)、拔管后20 min(T_5)的MAP、HR、CVP,记录T_0—T_4时平均气道压(Pmean)和Cdyn。T_0—T_5时行血气分析,计算肺内分流率(Qs/Qt)和氧合指数(OI)。记录机械通气过程中去氧肾上腺素使用和术后肺部并发症情况。结果滴定组所获取的个体化PEEP为(12.38±2.67)cmH_2O。T_0—T_5时两组MAP、HR、CVP差异无统计学意义。T_0—T_4时两组Pmean差异无统计学意义。T_2—T_4时滴定组Cdyn明显高于对照组(P0.05),Qs/Qt明显低于对照组(P0.05)。T_2—T_5时滴定组OI明显高于对照组(P0.05)。滴定组去氧肾上腺素使用率明显高于对照组[10例(25%) vs 3例(8%),P0.05]。滴定组术后肺部并发症发生率明显低于对照组[2例(5%) vs 8例(20%),P0.05]。结论与恒定PEEP 5 cmH_2O比较,俯卧位脊柱手术老年患者术中滴定个体化PEEP,能够更好地改善氧合,降低肺内分流率,减少术后肺部并发症。     

肥胖患者腹腔镜结直肠癌根治术中实时食管压监测下呼气末正压通气对肺通气的影响

目的探讨实时食管压监测指导下设定呼气末正压(positive end expiratory pressure,PEEP)通气参数对肥胖腹腔镜结直肠癌根治术患者的临床价值。方法选择2016年1—12月收治的拟行腹腔镜结直肠癌根治术的肥胖患者90例,男50例,女40例,年龄40~65岁,BMI30kg/m2,ASAⅡ或Ⅲ级,采用随机数字表法将患者随机分为三组:P组、PEEP5组和PEEP10组,设置VT8ml/kg,分别在肺复张后给予个体化PEEP(采用实时食管压监测通过计算呼气末跨肺压=0cmH_2O和吸气末跨肺压=25cmH_2O确定最佳PEEP)、PEEP 5cmH_2O和10cmH_2O。观察气腹建立前(T0)、气腹建立后10min(T1)、气腹后头低40.5°足高位20 min(T2)和气腹结束(T3)时的呼吸力学指标。结果T1—T3时P组Ppeak、SBP明显低于,PaO_2/FiO_2明显高于PEEP5组和PEEP10组(P0.05);T2时P组Pplat、Raw明显低于PEEP5组(P0.05);T2、T3时P组Cst明显高于PEEP5组(P0.05);T1、T2时P组DBP明显低于PEEP5组和PEEP10组(P0.05)。结论实时食管压监测应用于PEEP通气的肥胖腹腔镜结肠癌手术患者,能够有效改善患者呼吸和循环功能。     

个体化呼气末正压对心肺转流下瓣膜手术患者肺功能的影响

目的探讨心脏瓣膜术中早期应用个体化呼气末正压(PEEP)对患者肺功能的影响。方法选择2019年7—10月择期行瓣膜手术的患者33例,男11例,女22例,年龄40～70岁,BMI 18～26 kg/m~2,ASAⅡ或Ⅲ级,心功能Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组:对照组(C组,n=17)和个体化PEEP组(P组,n=16),两组术中麻醉维持为全凭静脉麻醉。停机后P组采用阶梯PEEP法滴定适宜的PEEP,并维持至手术结束,C组设置固定PEEP 4 cmH_2O。记录手术前(T_0)、肺复张前(T_1)、肺复张后40 min(T_2)、术后2 h(T_3)、术后24 h(T_4)的氧合指数(PaO_2/FiO_2),T_0—T_2时的HR、MAP、CVP,T_1—T_3时的肺动态顺应性(Cdyn)。使用经胸超声检查并记录T_0、T_2—T_4时的肺超声评分(LUS评分)和术后肺部并发症的发生情况。结果与T_1时比较,T_2、T_3时P组PaO_2/FiO_2和Cdyn明显升高(P0.05)。与C组比较,T_2时P组PaO_2/FiO_2和Cdyn均明显升高(P0.05),T_2—T_4时P组LUS评分明显降低(P0.05),P组术后肺水肿的发生率明显降低(P0.05)。两组其余术后肺部并发症发生率差异无统计学意义。结论在心脏瓣膜手术心肺转流停机后早期应用个体化PEEP具有肺保护作用。     

不同气腹压力对腹腔镜妇科手术患者颅内压的影响

目的应用超声测量视神经鞘直径(ONSD)评价不同气腹压力下腹腔镜妇科手术患者颅内压(ICP)的变化。方法择期行腹腔镜妇科手术患者40例,年龄18～65岁,BMI 18～25 kg/m~2,ASAⅠ或Ⅱ级,采用随机数字表法分为两组(n=20):低气腹压力组(A组)和高气腹压力组(B组)。常规麻醉诱导和机械通气。手术开始时行CO_2气腹,A组气腹压力为10 mmHg,B组为14 mmHg。气腹后调整体位为30°头低脚高位,手术结束时恢复为仰卧位。超声测量患者右眼ONSD,根据ONSD计算ICP_(ONSD)。记录麻醉诱导后气腹前(T_0)、气腹后1min(T_1)、头低脚高位即刻(T_2)、气腹后30 min后(T_3)、气腹后60 min后(T_4)、手术结束后5 min(T_5)、15 min(T_6)时的P_(ET)CO_2、PaCO_2、MAP、HR、ONSD和ICP_(ONSD)。结果与T_0时比较,T_4、T_5时两组P_(ET)CO_2、PaCO_2明显升高,T_4—T_6时MAP明显升高(P0.05);T_4—T_6时A组,T_3—T_6时B组HR明显增快(P0.05)。与A组比较,T_3、T_4时B组MAP明显升高,HR明显增快(P0.05)。与T_0时比较,T_4、T_5时A组ONSD、ICP_(ONSD)明显升高,T_3—T_5时B组ONSD、ICP_(ONSD)明显升高(P0.05)。与A组比较,T_3时B组ONSD、ICP_(ONSD)明显升高(P0.05)。结论 10 mmHg和14 mmHg气腹压力均可引起腹腔镜妇科手术患者ONSD和ICP升高,其中14 mmHg气腹压力对ONSD和ICP的影响更大。     

驱动压指导PEEP滴定对机器人辅助根治性前列腺切除术老年患者呼吸功能的影响北大核心CSCD

目的观察驱动压(DP)指导呼气末正压(PEEP)滴定对机器人辅助根治性前列腺切除术(RARP)老年患者呼吸功能的影响。方法选择2020年9月至2021年9月择期全麻下行RARP的老年患者40例,年龄65~80岁,BMI 19~28 kg/m^(2),ASAⅡ或Ⅲ级。将患者随机分为两组:DP指导组(D组)和对照组(C组),每组20例。D组:机械通气后,PEEP从4 cmH_(2)O开始,以1 cmH_(2)O增幅逐渐增加,每个PEEP水平维持4 min,计算并记录4 min内最后1次呼吸循环的DP值,寻找DP最低值,此时对应的PEEP为平卧位时的最佳PEEP。屈氏体位且气腹建立后重复上述操作,滴定屈氏体位气腹下的最佳PEEP,直至手术结束。C组:以5 cmH_(2)O的固定PEEP进行机械通气。记录平卧位最佳PEEP设置完成后(C组固定PEEP通气后)4 min(T_(1))、屈氏体位气腹后滴定的最佳PEEP通气(C组改变体位与建立气腹后)1 h(T_(2))、2 h(T_(3))血气分析结果、气道峰压(Ppeak)、气道平台压(Pplat)、肺动态顺应性(Cdyn),并计算肺泡动脉氧分压差(A-aDO_(2))、氧合指数(OI)、呼吸指数(RI)、死腔/潮气量比值(V_(D)/V_(T)),记录T_(1)、T_(3)、拔管后1 min(T_(4))、术后2 h(T_(5))血清白细胞介素-6(IL-6)、白细胞介素-8(IL-8)、肿瘤坏死因子-α(TNF-α)浓度。记录术后肺部并发症(PPCs)的发生情况。结果与C组比较,D组T_(1)、T_(2)、T_(3)时PaO_(2)、Cdyn、OI明显升高(P<0.05),A-aDO_(2)、RI明显降低(P<0.05),T_(1)、T_(3)、T_(4)、T_(5)时血清IL-6、IL-8、TNF-α浓度明显降低(P<0.05)。两组术中Ppeak、Pplat、PaCO_(2)、V_(D)/V_(T)差异无统计学意义。两组均未发生PPCs。结论最小驱动压指导最佳呼气末正压设置能够改善机器人辅助根治性前列腺切除术老年患者术中呼吸功能,提高患者氧合。     

最佳呼吸末正压肺保护通气策略对腹腔镜下结直肠癌根治术患者氧合功能的影响

目的探讨最佳呼吸末正压(PEEP)肺保护通气策略对腹腔镜下结直肠癌根治术患者围术期氧合功能的影响。方法择期行腹腔镜下结直肠癌根治术患者54例,男36例,女18例,年龄65～85岁,ASAⅡ或Ⅲ级。随机分为两组:传统组(T组)和保护组(P组),每组27例。T组设置V_T 9 ml/kg且无PEEP和肺复张(RMs);P组通过肺动态顺应性(Cdyn)PEEP滴定确定患者最佳PEEP值,设置低V_T 7 ml/kg联合最佳PEEP,每30分钟RMs一次。于麻醉诱导后10 min(T_1)、每次RMs后30 min(T_2、T_3、T_4)记录Cdyn及气道平台压(Pplat)、并在T_1—T_4、拔管后30 min(T_5)及术后第3天(T_6)采集动脉血样本,计算氧合指数(OI),记录术前和T_6时的改良临床肺部感染评分(mCPIS)。结果与T组比较,T_3、T_4时P组Cdyn明显升高(P0.05),T_4—T_6时P组OI明显升高(P0.05),T_6时P组mCPIS明显降低(P0.05)。结论最佳PEEP联合低V_T和RMs的肺保护通气策略可改善腹腔镜结直肠癌根治术患者围术期氧合,降低mCPIS。     

经皮肾镜取石术中不同通气策略对视神经鞘直径的影响

目的观察在经皮肾镜取石术(percutaneous nephrolithotomy, PCNL)中采用肺保护性通气模式对视神经鞘直径(optic nerve sheath diameter, ONSD)的影响。方法全身麻醉下行择期PCNL患者30例,男19例,女11例,年龄≥18岁,ASAⅠ—Ⅲ级,采用随机数字表法将患者随机分为两组,每组15例。常规机械通气组(C组)设置V_T 8 ml/kg,PEEP 0 cmH_2O;肺保护性通气组(P组)设置V_T 6 ml/kg,PEEP 5 cmH_2O。分别在麻醉诱导前5 min(T_0)、改俯卧位前5 min(T_1)、俯卧位后10 min(T_2)、1 h(T_3)、改平卧位后10 min(T_4)应用床旁超声实时测量左右眼球后3 mm处ONSD。分别在T_1—T_4时采集动脉血进行血气分析,计算氧合指数(OI)。术后随访患者恶心呕吐、头晕、头痛以及肺部并发症的发生情况。结果与T_1时比较,T_2—T_4时两组双侧ONSD明显增加(P0.05)。与T_3时比较,T_4时两组双侧ONSD明显减小(P0.05)。与C组比较,T_3、T_4时P组OI明显升高(P0.05)。两组术后恶心呕吐、头晕、头痛以及肺部并发症发生率差异无统计学意义。结论经皮肾镜取石术中,俯卧位可显著增加患者的ONSD,但平卧位或俯卧位下行小潮气量联合低水平PEEP通气策略对ONSD无明显影响。     

肺保护性通气在老年患者腹腔镜子宫内膜癌根治术中的应用

目的探讨肺保护性通气在老年患者腹腔镜子宫内膜癌根治术中的应用效果。方法选择2019年6月至2020年6月择期行腹腔镜子宫内膜癌根治术的老年女性患者60例,年龄65～80岁,BMI 20～28 kg/m~2,ASAⅠ或Ⅱ级。采用随机数字表法将患者分为两组:肺保护性通气组(P组)和常规机械通气组(R组),每组30例。P组设置V_T 7 ml/kg、呼气末正压通气(PEEP) 7 cmH_2O、每30分钟规律手法肺复张一次;R组仅设置V_T 9 ml/kg,未采用PEEP和肺复张。记录气腹前即刻、气腹后2 h、手术结束即刻的气道峰压(Ppeak)、气道平台压(Pplat)、肺动态顺应性(Cdyn)及血清IL-6、IL-8、TNF-α浓度。记录气腹前即刻和出复苏室即刻的氧合指数(PaO_2/FiO_2)。结果与气腹前即刻比较,气腹后2 h、手术结束即刻两组Pplat、Ppeak及血清IL-6、IL-8、TNF-α浓度均明显升高(P0.05),Cdyn明显降低(P0.05);出复苏室即刻两组PaO_2/FiO_2明显降低(P0.05)。与R组比较,P组气腹后2 h、手术结束即刻Pplat、Ppeak及血清IL-6、IL-8、TNF-α浓度明显降低(P0.05),Cdyn明显升高(P0.05);出复苏室即刻PaO_2/FiO_2明显升高(P0.05)。结论肺保护性通气可以减轻老年患者腹腔镜子宫内膜癌根治术围术期呼吸功能损伤和炎症反应,可安全用于老年患者腹腔镜子宫内膜癌根治术。     

不同通气模式对Trendelenburg体位腹腔镜手术患者PaO_2和PaCO_2的影响

目的探讨压力控制通气(PCV)联合呼气末正压(PEEP)在Trendelenburg体位腹腔镜手术中对PaO_2和PaCO_2的影响。方法腹腔镜直肠癌根治术患者40例,年龄35~55岁,随机分为两组,每组20例。A组采用容量控制通气模式(VCV)通气[VT=体重(kg)×10ml]20min后,改用PCV模式通气20min,返回VCV模式继续通气20min后,采用PCV+低PEEP(5cm H_2O)模式通气20min。B组则将PCV与PCV+PEEP的顺序调换。在切换通气模式时行动脉血气分析。结果两组VCV模式时PaO_2均明显低于PCV模式及PCV+PEEP模式(P0.05)。PCV模式时PaO_2明显低于PCV+PEEP模式(P0.05);VCV模式时PaCO_2明显高于PCV模式和PCV+PEEP模式(P0.05),而PCV模式和PCV+PEEP模式时PaCO_2差异无统计学意义。VCV模式时动脉血pH值明显低于PCV和PCV+PEEP模式(P0.05),PCV和PCV+PEEP模式时动脉血pH值差异无统计学意义。结论 Trendelenburg体位腹腔镜手术时采用PCV+PEEP通气模式,与单纯VCV或单纯PCV模式比较,在提高PaO_2以及降低PaCO_2方面更具优势。     

呼气末正压通气对二氧化碳气腹病人动脉血氧合的影响

目的观察腹腔镜手术期间呼气末正压通气(PEEP)对二氧化碳气腹病人动脉血氧合及血液动力学的影响。方法20例ASAⅠ～Ⅱ级经腹腔镜肾上腺肿块、输尿管上段结石及肾切除的病人,随机均分为P组和C组。50%氧气混合空气机械通气,P组予以5cmH2O的PEEP,C组无PEEP。观察建立二氧化碳气腹前(T0)、气腹后10min(T1)、30min(T2)、1h(T3)和2h(T4)的PaO2、PaCO2、HR及MAP。结果P组气腹期间PaO2有上升趋势,而C组呈下降趋势,气腹后1hC组显著低于P组(P<0.05)。两组MAP和HR波动均未超过11%。结论腹腔镜手术期间PEEP能促进动脉血氧合,对循环影响较小。     

股静脉测压法和膀胱测压法在危重患者腹内压监测中的比较

目的：比较股静脉测压法和膀胱测压法在危重患者腹内压（IAP）监测中的应用价值.方法：对2013年1-6月住院治疗的20例ICU重症患者,分别使用两种测压方法进行IAP监测,均每8 h 1次,连续测定3 d,每次随机选择两种方法的测量顺序,共测量720次,比较两种测压法在读数精准性、测压数值、操作时间、并发症和医护人员满意度等方面的异同.结果：股静脉测压法所测压力数值与膀胱测压法相近[（14.14±4.33）mmHg比（12.91±4.75）mmHg,P〉0.05];但是股静脉测压法的操作时间[（57.94±19.00）s]较膀胱测压法更短[（112.49±27.07）s,P〈0.05];股静脉测压法读数精准率（84.44%）较膀胱测压法（49.44%）高（P〈0.01）,操作并发症低至1.1%（4例次）,远低于膀胱测压法的5.3%（19例次,P〈0.05）;医护人员满意度达（3.90±0.26）分,优于膀胱测压法[（2.48±0.19）分,P〈0.01].结论：相对于膀胱测压法而言,股静脉测压法具有测压值相似、操作时间短、读数精准度高、操作并发症少、接纳度高等优点,值得在危重患者IAP监测中推广.     

间歇正压通气和呼气末正压通气对犬眼内压的影响

目的 探讨间歇正压通气(IPPV)和呼气末正压通气(PEEP)对犬眼内压(10P)的影响.方法 实验犬8只,麻醉后分别监测基础条件下和各种机械通气条件下的IOP、CVP、MAP.结果 实施20 ml/kg和30 ml/kg两种不同潮气量的IPPV时IOP差异无统计学意义.实施10、15、20cm H20三种不同压力值的PEEP时IOP均显著升高(P<0.01).结论 IPPV对IOP影响不大,PEEP可使IOP显著升高.     

Iliac venous pressure estimates central venous pressure after laparotomy

Background

Central venous pressure (CVP) is traditionally obtained through subclavian or internal jugular central catheters; however, many patients who could benefit from CVP monitoring have only femoral lines. The accuracy of illiac venous pressure (IVP) as a measure of CVP is unknown, particularly following laparotomy.

Methods

This was a prospective, observational study. Patients who had both internal jugular or subclavian lines and femoral lines already in place were eligible for the study. Pressure measurements were taken from both lines in addition to measurement of bladder pressure, mean arterial pressure, and peak airway pressure. Data were evaluated using paired t-test, Bland-Altman analysis, and linear regression.

Results

Measurements were obtained from 40 patients, 26 of which had laparotomy. The mean difference between measurements was 2.2 mm Hg. There were no significant differences between patients who had laparotomy and nonsurgical patients (P = 0.93). Bland-Altman analysis revealed a bias of 1.63 ± 2.44 mm Hg. There was no correlation between IVP accuracy and bladder pressure, mean arterial pressure, or peak airway pressure.

Conclusions

IVP is an adequate measure of CVP, even in surgical patients who have had recent laparotomy. Measurement of IVP to guide resuscitation is encouraged in patients who have only femoral venous catheter access.     

Intra-abdominal pressure measurement: validation of intragastric pressure as a measure of intra-abdominal pressure

Background: The diagnosis of abdominal compartment syndrome depends uponthe demonstration of an elevated intra-abdominal pressure (IAP).Direct measures of IAP are impractical in the critical careunit; intravesical pressure (IVP) and intragastric pressure(IGP) should represent acceptable surrogate measures. IVP isthe preferred measure of IAP in critical care. We consideredthat IGP represents a practical alternative. The objective ofthis preliminary study was to observe the relationship betweenIGP and IAP. Methods: After Institutional Ethics Board approval, 29 patients havingelective laparoscopic surgery were recruited. IAP was measureddirectly via the abdominal trochar. This was compared with IGPmeasured via a commercial balloon catheter placed into the stomach. Results: Measured IGP was always more positive than IAP; both showedlinear correlation (r²>0.9). When IGP was calibrated againstIAP, an estimated difference between the IGP and IAP of ±2.5 mm Hg for 95% of the measurements was seen. Conclusions: The study demonstrates the strength of the relationship betweenIGP and IAP in normal individuals. Application of IGP measurementin the critical care patient is necessary to demonstrate itssuitability for continuous IAP assessment.     

Changes in intracranial pulse pressure amplitudes after shunt implantation and adjustment of shunt valve opening pressure in normal pressure hydrocephalus

Summary Background  We have previously reported that the intracranial pulse pressure amplitudes were elevated in idiopathic normal pressure hydrocephalus (NPH) patients responding to shunt surgery. Whether or not shunt implantation or adjustment of the shunt valve opening pressure modifies the intracranial pulse pressure amplitudes in NPH patients remains to be established. This report summarises our observations. Patients and methods  Thirteen patients with NPH (idiopathic in nine and secondary in four) are presented in whom continuous intracranial pressure (ICP) monitoring was done before and after shunt implantation. In two, ICP monitoring was also done during adjustment of shunt valve opening pressure. The mean ICP and mean ICP wave amplitude (i.e. pulse pressure amplitudes) were determined in 6-s time windows. Results  After shunt implantation there was a fall in both mean ICP and mean ICP wave amplitude; the reduction in the two ICP parameters correlated significantly. However, mean ICP in the supine position was normal (i.e. <15 mmHg) in 12 of 13 patients before shunt placement, and remained normal after shunting. According to our criteria, the mean ICP wave amplitudes were elevated before shunting in 12 of 13 patients and became “normalised” the day after shunting in nine patients. The reduction in mean ICP wave amplitude after shunt was highly significant at the group level. Moreover, adjustment of shunt valve opening pressure modified the levels of mean ICP wave amplitudes. Conclusions  The present observations in 13 NPH patients indicate that shunt implantation reduces mean ICP wave amplitudes. Moreover, the level of reduction can be tailored by adjustment of the shunt valve opening pressure.     

Telemetric recording of intrapleural pressure

BACKGROUND: Monitoring of intrapleural pressure (IPP) is used for evaluation of lung function in a number of pathophysiological conditions. We describe a telemetric method of non-invasive monitoring of the IPP in conscious animals intermittently or continuously for a prolonged period of time. MATERIALS AND METHODS: After IACUC approval, six mongrel dogs were used for the study. After sedation, each dog was intubated and anesthetized using 0.5% Isoflurane. A telemetric implant model TL11M2-D70-PCT from Data Science International was secured subcutaneously. The pressure sensor tip of the catheter from the implant was inserted into the pleural space, and the catheter was secured with sutures. The IPP signals were recorded at a sampling rate of 100 points/second for 30 to 60 min daily for 4 days. From these recordings, the total mean negative IPP (mmHg), and the total mean negative IPP for a standard time of 30 min were calculated. In addition, the actual inspiratory and expiratory pressures were also measured from stable recording of the IPP waveforms. RESULTS: In six dogs, the total mean +/- SD negative IPP was -10.8 +/- 10.6 mmHg. After normalizing with respect to acquisition time it was -13.2 +/- 11.2 mmHg/min. The actual inspiratory pressure was -19.7 +/- 15.3, and the expiratory pressure was -11.0 +/- 12.9. CONCLUSIONS: Our study demonstrates that telemetric monitoring of IPP can be performed reliably and non-invasively in conscious experimental animals. The values for IPP in our study are compatible with the results of other investigators who used different methods of IPP measurement. Further work may show this method to be helpful in understanding the pathophysiology of various breathing disorders.     

Associations between intracranial pressure, intraocular pressure and mean arterial pressure in patients with traumatic and non-traumatic brain injuries

Introduction

Anatomical proximity of the eye and the intracranial space is a fact but the existence of physiological and pathophysiological relationships between them is elusive. The objective of this study was to explore anatomical and pathophysiological interactions between the eye and the intracranial space and to assess clinical utility of intraocular pressure measurement in estimation of intracranial pressure in patients with brain injuries and to discover how haemodynamic instability could influence these interactions. Controversy surrounds the recent literature concerning this problem and the consensus has not been achieved.

Materials and methods

We evaluated the correlation between intracranial pressure and intraocular pressure, intracranial pressure and mean arterial pressure, intraocular pressure and mean arterial pressure in 40 patients with brain injuries initially comatose, admitted to our hospital. All patients required the intracranial pressure monitoring on clinical grounds. Simultaneous recordings of intracranial pressure, intraocular pressure and mean arterial pressure were performed.

Results

We calculated both the linear correlation coefficient and the Spearman rank-order correlation coefficient for all three relations. We found significant correlation between intraocular pressure and mean arterial pressure in 63% of the tested population. When the power of the test was increased, by considering only patients with 11 or more observations, this ratio increased to 76%. However, the correlation between intraocular pressure and intracranial pressure, as well as, between intracranial pressure and mean arterial pressure was not significant.

Conclusions

There is no anatomical and pathophysiological basis for the statement that intraocular pressure can be used as an indirect estimator of intracranial pressure.     

Our contemporary understanding of the aetiology of pressure ulcers/pressure injuries

In 2019, the third and updated edition of the Clinical Practice Guideline (CPG) on Prevention and Treatment of Pressure Ulcers/Injuries has been published. In addition to this most up‐to‐date evidence‐based guidance for clinicians, related topics such as pressure ulcers (PUs)/pressure injuries (PIs) aetiology, classification, and future research needs were considered by the teams of experts. To elaborate on these topics, this is the third paper of a series of the CPG articles, which summarises the latest understanding of the aetiology of PUs/PIs with a special focus on the effects of soft tissue deformation. Sustained deformations of soft tissues cause initial cell death and tissue damage that ultimately may result in the formation of PUs/PIs. High tissue deformations result in cell damage on a microscopic level within just a few minutes, although it may take hours of sustained loading for the damage to become clinically visible. Superficial skin damage seems to be primarily caused by excessive shear strain/stress exposures, deeper PUs/PIs predominantly result from high pressures in combination with shear at the surface over bony prominences, or under stiff medical devices. Therefore, primary PU/PI prevention should aim for minimising deformations by either reducing the peak strain/stress values in tissues or decreasing the exposure time.     

Blood pressure assessment in haemodialysis patients: Comparison between pre-dialysis blood pressure and ambulatory blood pressure measurement

Aim: Hypertension is common in haemodialysis (HD) patients. Determining the most appropriate method of blood pressure (BP) measurement, representative of target organ damage, is still an issue. BP variations between pre‐ and post‐HD treatment, or between on‐dialysis day and off‐dialysis day, are common. The aim of this study was to examine the possible differences between pre‐HD office BP (OBP) levels, inter‐HD (iHD) or HD day 24 h ambulatory BP measurement (ABPM) with 48 h ABPM, where the latter was considered the gold standard. Methods: 163 HD patients were studied. BP was monitored consecutively for 48 h with a Takeda TM2421 device, then sub‐analysed into two periods of 24 h: HD and iHD day. An average of 12 sessions pre‐HD OBP measurements was determined. Results: OBP significantly overestimates systolic (SBP) and diastolic BP (DBP) when compared with 48 h ABPM. SBP and DBP are significantly higher on iHD day than on HD day: 141.2 ± 20.8 versus 137.9 ± 20.9, and 77.1 ± 11.1 versus 76.1 ± 10.9 (P < 0.01). No differences of SBP night/day ratio were reported between 48 h ABPM and iHD 24 h ABPM or HD 24 h ABPM. The highest correlations were reported between 48 h SBP/DBP with iHD or HD 24 h ABPM (r² = 0.95, P < 0.001), while the lowest between 48 h SBP/DBP and OBP (r² = 0.40, P < 0.01, r² = 0.12, P < 0.01). The narrowest limits of agreement using the Bland and Altman test were reported between 48 h SBP or DBP and 24 h iHD or HD day ABPM. Considering 48 h ABPM, 80.5% of patients had BP higher than the norm, compared with 61.7% of patients in the case of OBP (χ² = 13.28, P < 0.001). The sensibility for detecting hypertension for iHD day 24 h ABPM was 98.4%, with specificity of 90%. The sensibility of 24 h HD day ABPM was 90.3%, with specificity 96.6%. In the case of OBP, sensibility and specificity were considerably lower, that is, 72.6% and 83.3% respectively. Conclusion: Significant differences are shown between OBP and 48 h ABPM in the recognition of a hypertensive state. OBP measurement has a lower sensibility and specificity than 24 h ABPM, which remains a valid alternative approach to 48 h ABPM in HD patients. Errors of OBP estimation should be taken into account, with possible negative impact on treatment strategies and epidemiology studies.