Relationship between postoperative hypoxemia and the operative site

The effect of the site of operation on postoperative hypoxemia was studied in 104 patients undergoing thoraco-abdominal, thoracic, upper abdominal, lower abdominal, extra-abdominal and non-thoracic operations. The degree of postoperative hypoxemia was the most extensive in patients undergoing thoraco-abdominal, moderate in thoracic and upper abdominal operations, and minimal in lower abdominal and other operations. On the other hand, the duration of hypoxemia also differed with the surgical procedures. Arterial oxygen tension returned to almost control values by the 3rd postoperative day in cases of lower abdominal and extremity operations and by the 7th postoperative day in those undergoing thoracic and upper abdominal surgery. Postoperative hypoxemia, however, remained throughout the fourteen day study period, in patients undergoing thoraco-abdominal operation. True shunt was measured in 27 patients with thoraco-abdominal, thoracic and upper abdominal operations. An increase in true shunt was evident postoperatively in the entire group of patients. The increase was significantly larger and longer lasting in cases of thoraco-abdominal incision than that in cases of thoracic and upper abdominal incision alone. Differences in postoperative true shunt between cases of thoracic and upper abdominal incisions were nil.     

Systemic administration of N–acetylcysteine has no effect on postoperative lung function following elective upper laparotomy in lung healthy patients

In a randomized, double-blind study, 131 consecutive patients, subjected to elective upper laparotomy, were prophylactically given the recommended dose of N-acetylcysteine (NAC) (Mucomyst, ASTRA) (200 mg x 3) or placebo against postoperative pulmonary complications. The effect was evaluated by lung function tests (VC and FEV1), arterial blood gas analyses and chest x-ray. No benefit could be demonstrated, either to postoperative pulmonary function or in the frequency of atelectasis in the recommended dose. However, no patients with preoperative bronchopulmonary disease demanding treatment with bronchodilatators were included in the study. A positive effect of NAC in this category of patients could not be excluded.     

Influence of anesthetic technique on early postoperative hypoxemia

In the present study we have compared the incidence and degree of hypoxemia during the early postoperative period and for the first 3 nights after operation occuring after the administration ot total intravenous anesthesia with propofol versus inhalation anesthesia with nitrous oxide and isoflurane.
We studied 50 consecutive non-obese patients, ages 25–65, ASA I-11, who were scheduled for elective cholecystectomy. Patients received randomly either total intravenous anesthesia with propofol (24 patients) or inhalation anesthesia with nitrous oxide and isoflurane (26 patients). Oxygen saturation was continously recorded on the night before surgery, for 8 hours after extubation (early postoperative period) and during the first, second and third nights after operation.
In the early postoperative period we found statistically significant higher values of mean (P<0.05) and minimum (P<0.01) SpO₂ in patients who received total intravenous anesthesia compared to patients in whom inhalation anesthesia was used. Moreover, in the early postoperative period, 4 (16.7%) patients of the intravenous anesthesia group versus 11 (42.3%) patients of the inhalation anesthesia group had at least 1 hypoxemic event (P<0.05).
We conclude that the incidence and degree of hypoxemia in the early postoperative period is significantly less when total intravenous anesthesia with propofol is used.     

Wearable device for prevention of postoperative and post-discharge hypoxemia: A randomized pilot trial

Background

The Oxalert Enhanced Pulse Oximeter (EPO) is a wearable device that detects and alerts patients to hypoxemia. In a preplanned pilot trial, we estimated the effect of continuous saturation monitoring with patient alerts on in-hospital and post-discharge saturation; we further assessed the feasibility of the intervention.

Methods

Noncardiac surgical patients were randomized to either the Oxalert with patient alerts (Monitor + Alert, N = 25) or the Oxalert without patient alerts (Monitor Only, N = 24). Monitoring continued during hospitalization for up to 6 days and for 24 h after hospital discharge. Patients in each group were compared on time-weighted average (TWA) SpO₂ <90% (%) and area under SpO₂ <90% (% * min) in-hospital and after discharge using the Wilcoxon rank sum test, with the treatment effect median difference and 95% confidence interval (CI) estimated using the Hodges–Lehmann estimator of location shift.

Results

We enrolled ≥2 patients per week, for a total of 49 patients in whom recording were obtained for a median [quartiles] of 91 [85, 95]% of the time in hospital. In-hospital, TWA SpO₂ <90% was a median [quartiles] of 0.11 [0.03, 0.25]% for Monitor + Alert and 0.29 [0.04, 0.71]% for Monitor-Only patients, with estimated median difference (95% CI) of −0.1 (−0.4, 0)%, p = .120. In hospital, the area under the curve (AUC) SpO₂ <90% was a median [quartiles] of 635 [204, 1513] % * min for Monitor + Alert and 1260 [117, 5278] % * min for Monitor-Only patients, with estimated median difference (95% CI) of −407 (−1816, 208) % * min, p = .349. Post-discharge, the estimated median difference (95% CI) was only −0.1 (−0.2, 0) %, p = .307.

Conclusions

The Oxalert system was well tolerated in both groups and enrollment was strong. Patients randomized to active Oxalert systems experienced half as many postoperative desaturation events while hospitalized, although the difference was not statistically significant in this small pilot trial. In contrast, the Oxalert system did not reduce post-discharge desaturation. Detecting postoperative deterioation in surgical patients after they arrive on regular hospital wards, and even after they have been discharged home, can potentially facilitate necessary “rescue” interventions. Wearable devices assessing vital signs, including oxygenation, are a practical requirement. In this pilot study, a wearable pulse oximeter, with and without hypoxemia alarms, was tested for feasibility and acceptability for signal collection in postoperative cases, including at home. Results indicate that a full-scale trial is warranted to test for possible clinical benefit with this type of “wearable” where late postoperative hypoxia could be a concern. The trial was registered at ClincialTrial.gov (NCT04453722).     

Atelectasis during anaesthesia and in the postoperative period

Transverse sections of lung tissue were studied in patients by computerized tomography during anaesthesia and in the postoperative period. Eight patients were studied during intravenous (thiopentone) and six during inhalational (halothane) anaesthesia. The latter patients were studied during both spontaneous and mechanical ventilation. Five of the patients who underwent surgery for inguinal hernia and five patients in whom laparotomy was performed were studied 1 h and 24 h postoperatively. No patient showed any lung changes while awake preoperatively, and all patients developed dependent, crest-shaped lung densities within 5-10 min of anaesthesia. The densities comprised 3.4% of the lung volume in the caudal (basal) 5 cm of the lung tissue. No significant differences in the size and distribution of the densities were noted between spontaneous breathing and mechanical ventilation during anaesthesia, or between intravenous and inhalational anaesthesia. The densities remained in nine of ten patients 1 h postoperatively, and they remained in five of ten patients 24 h after anaesthesia. The densities are considered to be compression atelectases which may develop as a result of relaxation of the diaphragm. They may be important contributors to postoperative pulmonary complications.     

PaO2 during anaesthesia and years of smoking predict late postoperative hypoxaemia and complications after upper abdominal surgery in patients without preoperative cardiopulmonary dysfunction

Background: The incidence of late postoperative hypoxaemia and complications after upper abdominal surgery is 20–50% among cardiopulmonary healthy patients. Atelectasis development during anaesthesia and surgery is the main hypothesis to explain postoperative hypoxaemia. This study tested the predictive value of PaO₂<19 kPa during combined general and thoracic epidural anaesthesia and the preoperative functional residual capacity (FRC) reduction in the 30° head tilt‐down position for the development of late prolonged postoperative hypoxaemia, PaO₂<8.5 kPa for a minimum of 3 out of 4 days, and other complications. Methods: Forty patients without cardiopulmonary morbidity, assessed by ECG, spirometry, FRC and diffusion capacity preoperatively, underwent upper abdominal surgery. PaO₂ during anaesthesia and preoperative FRC reduction were compared to known risk factors for the development of hypoxaemia and complications: age, pack‐years of smoking and duration of operation. The effect of optimizing pulmonary compliance with peroperative positive end‐expiratory pressure (PEEP) on postoperative hypoxaemia and complications was evaluated in a blinded and randomized manner. Results: Late prolonged postoperative hypoxaemia and other complications were found in 37% and 38% of the patients, respectively. Patients with PaO₂>19 kPa during anaesthesia with F_IO₂=0.33 exhibited a risk, irrespective of PEEP status, of suffering late prolonged hypoxaemia of 0% (0;23) and patients with PaO₂<19 kPa a risk of 52% (32;71), P<0.005. Having smoked more than 20 pack‐years was associated with a 47% (19;75) higher incidence of postoperative complications than having smoked less than 20 pack‐years, P<0.006. Conclusions: PaO₂ during anaesthesia and smoked pack‐years provide new tools evaluating patients undergoing upper abdominal surgery in order to predict the patients who develop late postoperative hypoxaemia and complications.     

The relationship between pre-operative symptoms, operative findings and postoperative complications in schwannomas

This study presents a retrospective review of the management of schwannomas in the limbs and examines the relationship between pre-operative clinical examination, operative findings and postoperative neurological complications. Eighteen tumours with a histological diagnosis of schwannoma in 17 patients who underwent surgery between 1998 and 2004 were the basis of this study. Enucleation of the tumour was possible in 14 cases. None of these patients had neurological complications pre-operatively but eight had mild neurological complications postoperatively. The complications consisted of sensory deficit in five cases, motor weakness in one and both in two. Enucleation of the tumours was impossible in four cases. These schwannomas originated in the brachial plexus in three cases and the ulnar nerve in the proximal arm in one case. Tumours with pre-operative symptoms and masses located at a proximal site in the limb were more likely to be impossible to enucleate completely.     

Evaluation of the risk of postoperative pulmonary complications

Ten of 40 patients who underwent major thoracic or abdominal operations developed postoperative pulmonary complications, consisting of six massive atelectasis, three pneumonias and one edema. They were mostly thoracotomy cases and cigarette smokers. Many of these complications would have been prevented, if reliable pulmonary function tests are available to predict preoperatively such occurrence. Flow-volume curve tracing and closing volume measurement were evaluated in this respect. Both flow at the point of functional residual capacity on flow-volume curve, and the closing capacity subtracted from functional residual capacity were found to be well correlated with the occurrence of postoperative complications and can be used to evaluate the risk of pulmonary complications developing in postoperative period.     

The other Pasteur Changing views on the postoperative chest

The life and works of William Pasteur (1855-1943) are described and his thesis that pulmonary collapse is the harbinger of the development of postoperative lung pathology is discussed.     

Risk factors for postoperative surgical site wound problems after metastatic and primary spine tumour surgery: A meta-analysis

A meta-analysis study was conducted to assess the risk factors (RFs) for postoperative surgical site wound problems (POSSWPs) after metastatic and primary spine tumour surgery (STS). A comprehensive literature examination until February 2023 was implemented, and 1786 linked studies were appraised. The 18 picked studies contained 18 580 subjects with surgery in the studies' baseline with and without different RFs. Odds ratio (OR) in addition to 95% confidence intervals (CIs) were used to calculate the consequence of RFs for POSSWPs after metastatic and primary STS using the dichotomous and continuous styles and a fixed or random model. Subjects with surgical instrumentation in their surgery had a significantly higher rate of POSSWPs in STS (OR, 2.28; 95% CI, 1.49–3.49, P < 0.001) compared with those without surgical instrumentation. Subjects with preoperative chemotherapy had a significantly higher rate of POSSWPs in STS (OR, 1.81; 95% CI, 1.09–3.00, P = 0.02) compared with those without preoperative chemotherapy. Subjects with preoperative radiotherapy had a significantly higher rate of POSSWPs in STS (OR, 1.93; 95% CI, 1.12–3.34, P = 0.02) compared with those without preoperative radiotherapy. Subjects with corticosteroid intake had a significantly higher rate of POSSWPs in STS (OR, 2.89; 95% CI, 1.73–4.82, P < 0.001) compared with those without corticosteroid intake. No significant difference was found between males and females in the rate of POSSWPs in STS (OR, 0.95; 95% CI, 0.66–1.37, P = 0.78). Surgical instrumentation, preoperative chemotherapy, preoperative radiotherapy and corticosteroid are RFs for the higher rate of POSSWPs in STS; however, gender was not shown to be a risk factor. Though precautions should be taken when commerce with the consequences since some of the studies picked for this meta-analysis had low sample sizes.     

术后急性疼痛与慢性疼痛关系的研究进展

背景 术后急性疼痛管理仍然不尽人意,如何防治急性疼痛转化为慢性疼痛仍然是临床亟待解决的问题. 目的 阐述术后急性疼痛转化为慢性疼痛的研究进展,为术后疼痛管理以减少慢性疼痛的发生提供参考. 内容 就急性疼痛转化为慢性疼痛的可能性等方面作一综述. 趋向 进一步研究术后急性疼痛转化为慢性疼痛的机制,以明确有效的预防急性疼痛慢性化的方法.     

Arterial oxygen desaturation during postoperative transportation: the influence of operation site

Arterial oxygen saturation in 132 patients was measured using a Biox IV oximeter with an ear probe, during transfer from theatre to recovery room following a variety of surgical procedures. Oxygen saturation decreased to 85% or less in 21.9% of patients and to 90% or less in 61.4%. No predictive factors were identified. It is recommended that supplementary oxygen be given to all patients in the immediate postoperative period, including the period of transit to the recovery room.     

An Analysis of the Predictability of Hypoxemia Following Vertical Banded Gastroplasty

Postoperative (post-op) hypoxemia is unpredictable, often undetected by physical examination, sometimes fatal. We studied 45 morbidly obese patients with an average age of 37, including 16 smokers, having vertical banded gastroplasty (VBG) for useful preoperative (pre-op) predictor(s) of post-op hypoxemia during the first five days following VBG. Patient blood gases (arterial blood oxygen, P_aO₂, in mmHg), pre-op and five post-op days (POD), after 30 min in room air were: pre-op, 85 ± 9; POD1, 63 ± 9*; POD2, 61 ± 9*; POD3, 63 ± 10*; POD4, 63 ± 9*; POD5, 64 ± 11*. (*p < 0.05, Student's t-test compared with pre-op). Linear regression showed no practical, predictive value for P_aO₂ for age, Body Mass Index (BMI), pulmonary function tests (PFTs), smokers or preop P_aO₂. Post-op atelectasis occurred in 84% of patients, mostly the posterior basilar regions on chest X-ray. No patient developed clinically diagnostic pneumonia. VBG patients experienced profound hypoxemia post-op, the lowest on POD2. There is no reliable method to predict which patient may develop severe hypoxemia. It is, therefore, extremely helpful to uniformly monitor P_aO₂ post-op in morbidly obese patients.     

术前硬膜外激素注射是否增加腰椎术后手术部位感染风险的Meta分析

目的 :通过Meta分析明确术前腰椎硬膜外激素注射(lumbar epidural steroid injection,LESI)是否增加后续腰椎手术术后手术部位感染(surgical site infection,SSI)风险。方法:检索Pubmed、Embase、Cochran Trail数据库,检索时间均是从建库到2018年7月。筛选出比较腰椎术前行LESI及未行LESI患者术后90d内SSI发生率的对照研究,各研究的观察(暴露)组为接受LESI并后续相同节段行首次腰椎手术,对照(非暴露)组为未行LESI而于相同节段行首次腰椎手术。各组病例数均大于100,随访时间至少90d。评价指标为术后90d内SSI发生率。依据LESI注射距后续腰椎手术时间分亚组(1个月内,1～3个月,3～6个月,6～12个月),合并SSI比值比(OR)。使用Newcastle-Ottawa Quality Scale(NOS)评分评价纳入研究质量。分别行亚组分析探讨异质性,敏感性分析测定合并结果稳定性,Egger′s回归检测发表偏倚。结果:共5篇文献纳入研究,其中4篇为回顾性病例对照研究,1篇为回顾性队列研究,研究质量NOS评分均在6分以上。共纳入225801例患者,其中暴露组38452例,对照组187349例。经Meta分析,术前1个月内行LESI,暴露组与对照组术后90d内SSI发生率比较OR=2.15(95%CI,1.30～3.55),P0.05;术前1～3个月行LESI,暴露组与对照组术后90d内SSI发生率比较OR=1.54(95%CI,1.36～1.74),P0.05;术前3～6个月行LESI,暴露组与对照组术后90d内SSI发生率比较OR=1.09(95%CI,0.94～1.26),P0.05;术前6～12个月行LESI,暴露组与对照组术后90d内SSI发生率比较OR=1.30(95%CI,0.88～1.93),P0.05。Meta分析亚组分析证实基线资料不匹配为显著异质性来源,敏感性分析证实Meta分析结果稳定,发表偏倚检测提示未见发表偏倚。结论:术前3个月内行LESI显著增加后续腰椎手术术后90d内SSI风险。     

Relationship between perioperative blood transfusion and surgical site infections in pediatric general and thoracic surgical patients

Background

Recently, perioperative transfusions were demonstrated to be associated with higher rate of surgical site infections (SSIs) in neonates. We sought to examine whether a similar relationship exists between perioperative blood transfusions and SSI among non-neonatal pediatric general surgical patients.

允许性低氧血症理论与实践研究进展

背景 允许性低氧血症是指对于难治性低氧的危重患者在相对较低的氧饱和度的情况下,通过优化心输出量（cardiac output,CO）,部分代偿呼吸功能,维持正常氧供（delivery of oxygen,DO2）,减少机械通气对肺部和全身的损害。目的 对目前允许性低氧血症理论与实践进展综述,为进一步的研究与讨论提供基础。内容 阐述允许性低氧血症的基本概念、起源、理论基础、研究进展及临床实践可能需要关注的问题。 趋向 理论上允许性低氧血症能够改善危重患者的临床预后,但仍需更多的临床实验来证明其在危重患者呼吸管理中的有效性和安全性。     

术中压力性损伤与受压部位微环境关系的研究

目的探究受压部位微环境与俯卧位手术患者发生术中压力性损伤的关系,为临床实施预防措施提供参考。方法选取择期手术患者99例,获取患者人口学及手术相关资料,以及受压部位皮肤温度和皮肤湿度情况。结果俯卧位手术患者术中压力性损伤发生率为10.10%,多发生在手术结束后24 h内,颧骨及髂前上棘为好发部位。皮肤温度、核心温度升高是俯卧位手术患者压力性损伤的危险因素(OR值为8.215、7.186,均P<0.05)。结论受压部位微环境对俯卧位手术患者术中压力性损伤有影响,应采取针对性干预措施,降低术中压力性损伤发生率。