Anesthesia Management

Accidental Intra-arterial Injection

Severe digit or limb injury including amputation has occurred from accidental intra-arterial injection of medications as well as illicit drugs. Common sites include the brachial artery at the elbow or dorsum of the hand in the radial artery, as well as inadvertent injection into arterial lines in-situ.

The most severe limb injury has occurred after Pentothal, Diazepam, Penicillin, and Clindamycin. The most commonly injected illicit medications were crushed benzodiazepines (most commonly flunitrazepam). The potential for damage depends on the drug injected, and also its formulation – benzyl alcohol appears more harmful; commonly used agents like Propofol, Succinylcholine, Rocuronium, Fentanyl, amd Ketamine have not resulted in severe injury generally, although Propofol may cause severe pain.

Incidence is difficult to determine and has been estimated between 1:3,440 and 1:56,000 with old data. Mechanisms of injury can variously or in combination include direct endothelial injury, vasospasm, drug crystallization, and thrombosis.

Many empirical treatments have been reported with a less than strong evidence base, including steroids, vasodilators and nerve blocks. The most common regimes now recommended usually include anticoagulation with Heparin, Prostacyclin, and intra-arterial thrombolytics like TPA.

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Transfontanelle Ultrasound to Predict Fluid Responsiveness in Infants

Studies have found a relationship between fluid responsiveness and respiratory variation in the arterial blood flow peak velocity in the ascending aorta.

This was a prospective observational study of 30 infants undergoing cardiac surgery. Before and after the administration of 10ml · kg–1 crystalloid, established measures – respiratory variation of the aorta blood flow peak velocity, pulse pressure variation, and central venous pressure were obtained. The respiratory variation of the internal carotid artery blood flow peak velocity was measured using transfontanelle ultrasound.

In this study the respiratory variation of the internal carotid artery blood flow peak velocity as measured using transfontanelle ultrasound predicts an increase in stroke volume in response to an intravenous fluid bolus.

Cutoffs for respiratory variation were different than aortic velocity and further larger studies are needed in diverse populations before this potentially useful non-invasive fluid responsiveness assessment modality can be more widely recommended in infants.

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Volatile Anesthetics vs. Total Intravenous Anesthesia for Cardiac Surgery

The ‘cardioprotective’ effects of volatile anesthesia gases have been seen as useful during coronary artery bypass surgery (CABG). This controlled study in elective CABG compared volatile anesthesia with total intravenous anesthesia (TIVA) and found no difference in 30 day or 1 year mortality.

The findings are important as anesthetic gases have been even recommended as useful in American and European guidelines, based on known cellular protective effects and effects on cardiac biomarkers, and suggested by previous observational and meta-analysis studies.

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Cesarean Maternal & Neonatal Mortality in Africa

Maternal mortality after cesarean delivery in Africa is 50 times higher than that of high-income countries and is driven by peripartum haemorrhage and anaesthesia complications. Neonatal mortality is double the global average.

These shocking figures from a prospective observational study across Africa may be due to such factors as poor access to caesarean delivery, peripartum hemorrhage, and provision of anesthesia by non-physicians.

Suggested areas to improve include risk identification (eg, ASA status, risk of bleeding), care bundles and checklists and a higher level of monitoring, use of antifibrinolytic drugs (tranexamic acid), improved access to blood and blood products with long shelf lives, such as freeze-dried plasma and fibrinogen; and novel methods of training of non-physician anaesthetists, including online support and mobile-based applications.

Intraoperative Goal-directed Balanced Crystalloid versus Colloid

Another piece for the perpetual puzzle as to the harms and/or benefits of colloids vs. crystalloids.

The potential serious kidney injury and mortality using Hydroxyethyl Starch reported in critical illness are not always replicated in the intraoperative setting.

In this study in abdominal surgery, the primary outcome was a composite of serious postoperative cardiac, pulmonary, infectious, gastrointestinal, renal, and coagulation complications. Creatinine at 6 months was assessed.

Lactated Ringers or Hydroxyethyl Starch were given in a goal directed manner using esophageal Doppler based on stroke volume and corrected aortic flow time.

“Doppler-guided intraoperative hydroxyethyl starch administration did not reduce composites of serious complications. Nor did hydroxyethyl starch reduce the duration of hospitalization, but there was also no indication of renal or other toxicity”.

No clear reason to use Hydroxyethyl Starch is apparent, in view of the greater cost.

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Intravenous Dexmedetomidine and Dexamethasone for Postop Analgesia

Many agents have been added to peripheral nerve blocks to prolong analgesia. In some cases intravenous administration has been as successful without potential nerve toxicity concerns.

This small randomized study evaluated the difference in time to first rescue analgesic request between patients receiving co-administered intravenous dexamethasone and dexmedetomidine and patients receiving intravenous dexamethasone alone after single-shot interscslene brachial plexus block for arthroscopic shoulder surgery. Saline controls were used.

Co-administration of intravenous dexamethasone (0.11 mg kg−1) with dexmedetomidine (1.0 μg kg−1) significantly prolonged the time to first rescue analgesic request more than Dexamethasone alone, and both more so than saline controls. Also both groups had reduced postoperative opioid consumption, less sleep disruption and improved patient satisfaction compared with the control group.

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Intravenous Acetaminophen & Hip and Kneee Arthroplasty

Intravenous Acetaminophen was hailed as a useful addition to anesthesia care, but almost every study has shown little to be gained compared to oral Acetaminophen.

This latest, albeit a database study in total hip and knee arthroplasty, once again shows no (or less) benefit compared to oral Acetaminophen, which should always where possible be the first choice.

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Acute Pain Trajectories and Remote Pain Resolution

A secondary analysis of the Stanford Accelerated Recovery Trial assessed remote postoperative pain, opioid use, and recovery. The incidence of persistent postsurgical pain ranges from 10% to 50%, and 2% to 10% of patients report severe, chronic pain after surgery.

The study assessed high and low pain clusters in the first 10 days in a mixed surgical cohort. Numerous pain and other scores were administered. The authors identified worst pain over the past 24 hours reported on postoperative day 10 as a significant immediate postoperative predictor of remote pain resolution, opioid cessation, and complete surgical recovery.

The implications are summarized: “Ultimately, early identification of high-risk patients would facilitate personalized care with closer follow-up, earlier referral for specialist care, and extension of multimodal pain regimens”.

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Lidocaine and Neurologic Outcomes after Cardiac Surgery

50% of cardiac surgery patients leave hospital with cognitive dysfunction which tends to improve but may persist at 5 years in some. Based on previous suggestion that Lidocaine may ameliorate such issues due to postulated anti-inflammatory, blood flow, and cerebral metabolism mechanisms, this randomized study failed to find benefit with use of Lidocaine infusion during and for 48 hours after cardiac surgeries.

Conclusion: Intravenous lidocaine administered during and after cardiac surgery did not reduce postoperative cognitive decline at 6 weeks.

The authors note the complex issues involved in cognitive dysfunction that could not be expected to benefit from a single agents – preoperative cognitive impairment, genetic predisposition, cerebral microembolism or hypoperfusion during CPB, inflammatory responses, hemodilution, hyperglycemia, hyperthermia, unmasking of Alzheimer disease, and acceleration of amyloid deposition associated with inhalational anesthetics.

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Prenatal surgery of fetal open spinal neural tube defects

A full text article describes some of the unique features of anesthesia for prenatal open and fetoscopic surgery of fetal open spinal neural tube defects.

For uterine relaxation, higher MACs of Sevoflurane were used, as well as nitroglycerin and tocolytics. Higher doses as well as greater hemodynamic disturbance occurred with open surgery. Colloids were used more, presumably to lower the risk of pulmonary edema which occurred in 10%, attributable to gestational physiologic changes, tocolytic administration and liberal fluid therapy.

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