Association between respiratory distress time and invasive mechanical ventilation in COVID-19 patients: A multicentre regional cohort study.

AIM: To determine whether the duration of respiratory distress symptoms in severe COVID-19 pneumonia affects the need for invasive mechanical ventilation and clinical outcomes. MATERIALS AND METHODS: An observational multicentre cohort study of patients hospitalised in five COVID-19-designated ICUs of the University Hospitals of Emilia-Romagna Region. Patients included were adults with pneumonia due to SARS-CoV-2 with PaO2/FiO2 ratio <300 mmHg, respiratory distress symptoms, and need for mechanical ventilation (invasive or non-invasive). Exclusion criteria were an uncertain time of respiratory distress, end-of-life decision, and mechanical respiratory support before hospital admission. MEASUREMENTS AND MAIN RESULTS: We analysed 171 patients stratified into tertiles according to respiratory distress duration (distress time, DT) before application of mechanical ventilation support. The rate of patients requiring invasive mechanical ventilation was significantly different (p < 0.001) among the tertiles: 17/57 patients in the shortest duration, 29/57 in the intermediate duration, and 40/57 in the longest duration. The respiratory distress time significantly increased the risk of invasive ventilation in the univariate analysis (OR 5.5 [CI 2.48-12.35], p = 0.003). Multivariable regression analysis confirmed this association (OR 10.7 [CI 2.89-39.41], p < 0.001). Clinical outcomes (mortality and hospital stay) did not show significant differences between DT tertiles. DISCUSSION: Albeit preliminary and retrospective, our data raised the hypothesis that the duration of respiratory distress symptoms may play a role in COVID-19 patients' need for invasive mechanical ventilation. Furthermore, our observations suggested that specific strategies may be directed towards identifying and managing early symptoms of respiratory distress, regardless of the levels of hypoxemia and the severity of the dyspnoea itself.

Intrathecal atropine to prevent postoperative nausea and vomiting after Cesarean section: a randomized, controlled trial.

BACKGROUND: Postoperative nausea and vomiting (PONV) is a common adverse effect of intrathecal morphine, especially after Cesarean section. This randomized controlled trial investigated the effects of intrathecal administration of a small-dose of atropine on postoperative nausea and vomiting after Cesarean section. METHODS: Parturients with ASA physical status class I-II scheduled for elective Cesarean section and consenting to spinal anesthesia were enrolled. They received 0.5% hyperbaric bupivacaine 12.5 mg, morphine 200 µg and one of the following three solutions: atropine 100 µg intrathecally and saline intravenously; saline intrathecally and atropine 100 µg intravenously; saline only both intravenously and intrathecally. We examined the incidence and severity of PONV, pain ratings and the need for analgesics. RESULTS: We followed 204 parturients. The incidence of PONV was 15%, 37% and 49% in the three groups, respectively (P<0.001). The relative risk reduction for PONV when using intrathecal atropine was 69% vs. placebo and 59% vs. intravenous atropine. No differences were noted in terms of postoperative pain. CONCLUSION: Intrathecal atropine had a significant antiemetic effect, making it a useful adjunct for intrathecal opioid-related PONV.

Clinical uses of low-dose ketamine in patients undergoing surgery.

Ketamine acts mainly as a N-methyl-D-aspartate receptor (NMDAr) antagonist. Originally developed as a general anesthetic, it is now seldom employed as such in richer countries due to the relatively high risk of psychotomimetic adverse effects. Recently, low-dose regimens in the range of 0.25-0.5 mg/kg as an initial bolus followed by 50-500 kappag/kg/h have been proposed as an adjuvant for postoperative analgesia and for the reduction of exogenous opioid-induced hyperalgesia. In this review, we examine the evidence for clinical usefulness of perioperative ketamine infusion and its role in the context of general and/or regional anesthesia.

Ultrasound vs nerve stimulation multiple injection technique for posterior popliteal sciatic nerve block.

In this prospective, randomised, observer-blinded study we evaluated whether ultrasound guidance can shorten the onset time of popliteal sciatic nerve block as compared to nerve stimulation with a multiple injection technique. Forty-four ASA I-III patients undergoing posterior popliteal sciatic nerve block with 20 ml of 0.75% ropivacaine were randomly allocated to nerve stimulation or ultrasound guided nerve block. A blinded observer recorded onset of sensory and motor blocks, success rates, the need for fentanyl intra-operatively, the requirement for general anaesthesia, procedure-related pain, patient satisfaction and side-effects. Onset times for sensory and motor blocks were comparable. The success rate was 100% for ultrasound guided vs 82% for nerve stimulation (p = 0.116). Ultrasound guidance reduced needle redirections (p = 0.01), were associated with less procedural pain (p = 0.002) and required less time to perform (p = 0.002). Ultrasound guidance reduced the time needed for block performance and procedural pain.

Intrathecal ropivacaine 5 mg/ml for outpatient knee arthroscopy: a comparison with lidocaine 10 mg/ml.

PURPOSE: The aim of this prospective, randomised, blind study was to compare the evolution of spinal block produced with 50 mg lidocaine 10 mg/ml and 10 mg ropivacaine 5 mg/ml for outpatient knee arthroscopy. METHODS: Thirty outpatients undergoing knee arthroscopy received 50 mg of lidocaine 10 mg/ml (n=15) or 10 mg of ropivacaine 5 mg/ml (n=15) intrathecally. The evolution of spinal block was recorded until home discharge, while the occurrence of transient neurologic symptoms (TNS) was evaluated through phone-call follow-ups. RESULTS: The median onset time was 15 (10-21) min with lidocaine and 24 (11-37) min with ropivacaine (P=0.109). Spinal lidocaine resulted in a faster resolution of sensory block [148 (130-167) min vs. 188 (146-231) (P=0.022)], unassisted ambulation with crutches [176 (144-208) min vs. 240 (179-302) min (P=0.014)], and voiding [208 (163-254) min vs. 293 (242-343) min (P=0.001)] than ropivacaine. Recovery of motor function required 113 (95-131) min with lidocaine and 135 (87-183) with ropivacaine (P=0.219). Six lidocaine patients reported TNS (40%) as compared with no patient receiving ropivacaine (0%) (P=0.005). CONCLUSIONS: Spinal block produced with 10 mg ropivacaine 5 mg/ml is as effective as that produced by 50 mg of lidocaine 10 mg/ml. Recovery of unassisted ambulation and spontaneous voiding occurred earlier with lidocaine, but this was associated with a markedly higher incidence of TNS.

Updating postoperative pain management: from multimodal to context-sensitive treatment.

Although a wealth of evidence exists on effective postoperative pain (POP) treatment, surgical patients still suffer from inadequate analgesic regimens, and outcomes have been shown to improve only within the context of tightly controlled, randomized trials. The pathophysiology of pain seems to suggest that analgesic regimens aimed at inhibition of neurotransmission and neuroplastic phenomena should be instituted immediately before the painful stimuli are applied. Several protocols have been proposed, but the final choice should be made according to patients' needs, surgical indications, and institutional resources. Optimal POP management may succeed in improving outcomes only when combined with hospital-wide protocols for early rehabilitation and recovery; in the absence of adequate monitoring, equipment, motivation and coordination, even state-of-the-art techniques may fail to show results in terms of returning to daily life. Analgesic efficacy should always be balanced against safety and the ability to monitor patients in order to reduce complications that may actually impair recovery. A ''context-sensitive'' approach to POP, therefore, is suggested. Context-sensitive analgesia should be instituted as early as deemed necessary to avoid persistent pain, and it should be continued, with different modalities, until full recovery from surgery. In this way, it should constitute a ''bridge'' therapy from surgery to full healing. The use of neuroprotective agents to reduce the risk of postoperative hyperalgesia and other sensory disturbances should be considered in the context of specific surgical interventions.

Transcutaneous carbon dioxide monitoring in spontaneously breathing, nonintubated patients in the early postoperative period.

BACKGROUND: The authors investigated the accuracy of transcutaneous capnometry (TcPCO(2)) in estimating arterial blood carbon dioxide partial pressure (PaCO(2)) during spontaneous breathing in patients admitted to our surgical intensive care unit (ICU). METHODS: Serial TcPCO(2) and PaCO(2) measurements were taken in stable patients undergoing postoperative monitoring after major abdominal, vascular, or thoracic surgery. Patients were enrolled 12 hours after extubation. Exclusion criteria were pulmonary dysfunction, hemodynamic instability, or anemia. Linear regression, mixed models, and Bland-Altman analyses were used to compare accuracy and correlation between the two variables. Data are presented as means (95% confidence intervals). RESULTS: PaCO(2) values ranged between 26 mmHg and 52 mmHg. Mean values for TcPCO(2) and PaCO(2) were 35.3 (33.8-36.8) mmHg and 39.2 (37.6-40.7) (P<0.001). Bland-Altman analysis showed a bias of -3.8 (-5.1-2.5) mmHg with upper and lower limits of agreement of 5.6 (3.4-7.9) mmHg and -13.3 (-15.6 -11.1) mmHg, respectively. Thirty-one (55.4%) measurements disagreed by 3 mmHg or more. Linear mixed model analysis with adjustment for repeated measurements showed low correlation (r=0.63; P<0.0005). There were small but significant differences between patients in the correlation coefficient (P=0.04). CONCLUSION: TcPCO(2) showed moderate bias with wide limits of agreement when compared to PaCO(2) in our patients. The regression model showed low correlation of the measurements when adjusting for repeated measurements and between-subject variances. TcPCO(2) may not provide an accurate quantitative estimation of PaCO(2) in stable, spontaneously breathing, nonintubated patients in the early postoperative period.

Effects of ultrasound guidance on the minimum effective anaesthetic volume required to block the femoral nerve.

BACKGROUND: We tested the hypothesis that ultrasound guidance may reduce the minimum effective anaesthetic volume (MEAV50) of ropivacaine 0.5% required to block the femoral nerve compared with nerve stimulation guidance. METHODS: After standard premedication and sciatic nerve block were given, 60 patients undergoing knee arthroscopy were randomly allocated to receive a femoral nerve block with ropivacaine 0.5% using either nerve stimulation (group NS, n = 30) or ultrasound (group US, n = 30) guidance. The volume of the injected solution was varied for consecutive patients based on an up-and-down staircase method according to the response of the previous patient. The initial volume was 12 ml. A double-blinded observer evaluated the occurrence of complete loss of pinprick sensation in the femoral nerve distribution, with concomitant block of the quadriceps muscle: positive or negative responses within 30 min after the injection determined a 3 ml decrease or increase for the next patient, respectively. RESULTS: The mean (sd) MEAV50 for femoral nerve block was 15 (4) ml (95% CI, 7-23 ml) in group US and 26 (4) ml (95% CI, 19-33 ml) in group NS (P = 0.002). The effective dose in 95% of cases (ED95) calculated with probit transformation and logistic regression analysis was 22 ml (95% CI, 13-36 ml) in group US, and 41 ml (95% CI, fs 24-66 ml) in group NS. CONCLUSIONS: Ultrasound guidance provided a 42% reduction in the MEAV of ropivacaine 0.5% required to block the femoral nerve as compared with the nerve stimulation guidance.

Stimulating or conventional perineural catheters after hallux valgus repair: a double-blind, pharmaco-economic evaluation.

BACKGROUND: We prospectively evaluated direct analgesia-related costs of continuous sciatic nerve block using either a stimulating or conventional catheter after hallux valgus repair. METHODS: The perineural catheter was inserted through a stimulating introducer either blindly (group Conventional, n= 38) or while stimulating via the catheter (group Stimulating, n= 38). Nerve block was induced with 25 ml of mepivacaine 15 mg/ml, and was followed 3 h later by a patient-controlled infusion of ropivacaine 2 mg/ml (basal infusion: 3 ml/h; incremental dose: 5 ml; lock-out time: 30 min). Rescue tramadol [100 mg intravenous (i.v.)] was given if required. Local anesthetic consumption, need for rescue tramadol and post-operative nausea and vomiting (PONV) treatment, and patient's satisfaction were recorded during first 24-h infusion. Cost calculations were based on the acquisition cost of drugs and devices. RESULTS: Both techniques were similarly effective, but local anesthetic consumption and need for rescue analgesics were lower in the Stimulating group [respectively, 120 vs. 153 ml (P= 0.004) and 21% vs. 60% (P= 0.001)]. The analgesia-related costs for 24 h were similar when 100-ml bags of ropivacaine 2 mg/ml were used (66 euro vs. 67 euro; P= 0.26). When 200-ml bags of ropivacaine were used, the analgesia-related costs were higher in the Stimulating group than the Conventional group (75 euro vs. 55 euro; P= 0.0005). CONCLUSIONS: Direct costs of continuous sciatic nerve block ranged from 55 to 75 euro. Stimulating catheters reduced local anesthetic consumption and need for rescue analgesics. This was only cost effective when 100-ml bags of 2 mg/ml ropivacaine were used, while the cheapest combination was the use of conventional catheters and 200-ml bags of ropivacaine.

Anatomy and imaging of lumbar plexus.

Sensory and motor innervation of the whole lower limb is due to lumbo-sacral-plexus that arises from the spinal roots L1-S3. The whole lower limb can be blocked from its origin to the foot for surgical procedures or for postoperative analgesia. Single or continuous lumbar plexus blockade can be an alternative to general anesthesia and central block in elective and traumatic hip or femur repair, for knee surgery and for postoperative analgesia. To understand the relative plexus depth and the relationship between the plexus and the closer structure in order to avoid complicance, the aid of imaging technique such as CT-scan, MRI and ultrasounds can be considered.

Thrombelastography. Present and future perspectives in clinical practice.

RESULTS: Thrombelastography (TEG) is a method for evaluating the viscoelastic properties of the blood clot, from its formation to its lysis. All major surgeries may be associated with massive blood loss, with blood component transfusion therapy often becoming mandatory. The clinician's goal is thus to optimize and possibly minimize blood components usage. To this end, TEG allows for a qualitative and dynamic analysis of the specific blood clotting process, from clot formation through its lysis, highlighting alterations at every single step in the cascade. With TEG is thus possible to know if bleeding is due to a failure to provide adequate surgical hemostasis, if there is platelet dysfunction, or to detect anomalies in coagulation proteases or their inhibitors, or if the blood loss is associated to early, excessive fibrinolysis. The theoretical advantages of TEG are the ease of performing the test, the fast sample reading times (now 30 minutes) and the informative