Management of a Fragmented Angiocatheter During Central Venous Cannulation: A Case Report and Important Lessons

Complications during central venous catheter (CVC) insertion are infrequent with an incidence of 0.1%-1%. We experienced a rare CVC complication with fragmentation of the angiocatheter at its hub during central venous cannulation while utilizing the modified Seldinger technique (ie, wire through the catheter technique). Vascular surgery was emergently required to remove the catheter fragment from the neck. Clinicians must remain vigilant during all aspects of CVC insertion, including awareness of the potential for fragmentation of the angiocatheter during its removal over the in situ guidewire. Prompt recognition and appropriate management included leaving the guidewire in place (to stabilize the distal fragmented segment) and promptly consulting vascular surgery for removal before potential vascular embolization of the angiocatheter fragment. We further recommend that all components of the insertion kit be inspected before and after patient use.

Adult Emergence Agitation: A Veteran-Focused Narrative Review

Emergence agitation (EA) is a self-limited state of psychomotor excitement during awakening from general anesthesia. EA is confined to the emergence period as consciousness is restored, which sharply distinguishes it from other postoperative delirium states. Sporadic episodes of EA may become violent with the potential for harm to both patients and caregivers, but the long-term consequences of such events are not fully understood. Current literature on EA in adults is limited to small-scale studies with inconsistent nomenclature, variable time periods that define emergence, a host of different surgical populations, and conflicting diagnostic criteria. Therefore, true incidence rates and risk factors are unknown. In adult noncardiac surgery, the incidence of EA is approximately 19%. Limited data suggest that young adults undergoing otolaryngology operations with volatile anesthetic maintenance may be at the highest risk for EA. Currently suggested EA mechanisms are theoretical but might reflect underblunted sympathetic activation in response to various internal (eg, flashbacks or anxiety) or external (eg, surgical pain) stimuli as consciousness returns. Supplemental dexmedetomidine and ketamine may be utilized for EA prevention. Compared to the civilian population, military veterans may be more vulnerable to EA due to high rates of posttraumatic stress disorder (PTSD) manifesting as violent flashbacks; however, confirmatory data are limited. Nonetheless, expert military medical providers suggest that use of patient-centered rapport tactics, PTSD trigger identification and avoidance, and grounding measures may alleviate hyperactive emergence phenomena. Future research is needed to better characterize EA in veterans and validate prophylactic measures to optimize care for these patients. This narrative review provides readers with an important framework to distinguish EA from delirium. Furthermore, we summarize current knowledge of EA risk factors, mechanisms, and adult management strategies and specifically revisit them in the context of veteran perioperative health. The anesthesiology care team is ideally positioned to further explore EA and develop effective prevention and treatment protocols.

Neuromuscular blockade management in the critically Ill patient

Neuromuscular blocking agents (NMBAs) can be an effective modality to address challenges that arise daily in the intensive care unit (ICU). These medications are often used to optimize mechanical ventilation, facilitate endotracheal intubation, stop overt shivering during therapeutic hypothermia following cardiac arrest, and may have a role in the management of life-threatening conditions such as elevated intracranial pressure and status asthmaticus (when deep sedation fails or is not tolerated). However, current NMBA use has decreased during the last decade due to concerns of potential adverse effects such as venous thrombosis, patient awareness during paralysis, development of critical illness myopathy, autonomic interactions, and even residual paralysis following cessation of NMBA use.

It is therefore essential for clinicians to be familiar with evidence-based practices regarding appropriate NMBA use in order to select appropriate indications for their use and avoid complications. We believe that selecting the right NMBA, administering concomitant sedation and analgesic therapy, and using appropriate monitoring techniques mitigate these risks for critically ill patients. Therefore, we review the indications of NMBA use in the critical care setting and discuss the most appropriate use of NMBAs in the intensive care setting based on their structure, mechanism of action, side effects, and recognized clinical indications. Lastly, we highlight the available pharmacologic antagonists, strategies for sedation, newer neuromuscular monitoring techniques, and potential complications related to the use of NMBAs in the ICU setting.

Perceptions of gender equity in departmental leadership, research opportunities, and clinical work attitudes: an international survey of 11 781 anaesthesiologists

BACKGROUND

Women make up an increasing proportion of the physician workforce in anaesthesia, but they are consistently under-represented in leadership and governance.

METHODS

We performed an internet-based survey to investigate career opportunities in leadership and research amongst anaesthesiologists. We also explored gender bias attributable to workplace attitudes and economic factors. The survey instrument was piloted, translated into seven languages, and uploaded to the SurveyMonkey® platform. We aimed to collect between 7800 and 13 700 responses from at least 100 countries. Participant consent and ethical approval were obtained. A quantitative analysis was done with χ² and Cramer's V as a measure of strength of associations. We used an inductive approach and a thematic content analysis for qualitative data on current barriers to leadership and research.

RESULTS

The 11 746 respondents, 51.3% women and 48.7% men, represented 148 countries; 35 respondents identified their gender as non-binary. Women were less driven to achieve leadership positions (P<0.001; Cramer's V: 0.11). Being a woman was reported as a disadvantage for leadership and research (P<0.001 for both; Cramer's V: 0.47 and 0.34, respectively). Women were also more likely to be mistreated in the workplace (odds ratio: 10.6; 95% confidence interval: 9.4-11.9; P<0.001), most commonly by surgeons. Several personal, departmental, institutional, and societal barriers in leadership and research were identified, and strategies to overcome them were suggested. Lower-income countries were associated with a significantly smaller gender gap (P<0.001).

CONCLUSIONS

Whilst certain trends suggest improvements in the workplace, barriers to promotion of women in key leadership and research positions continue within anaesthesiology internationally.

Vascular air embolism: A silent hazard to patient safety

PURPOSE

To narratively review published information on prevention, detection, pathophysiology, and appropriate treatment of vascular air embolism (VAE).

MATERIALS AND METHODS

MEDLINE, SCOPUS, Cochrane Central Register and Google Scholar databases were searched for data published through October 2016. The Manufacturer and User Facility Device Experience (MAUDE) database was queried for "air embolism" reports (years 2011-2016).

RESULTS

VAE may be introduced through disruption in the integrity of the venous circulation that occurs during insertion, maintenance, or removal of intravenous or central venous catheters. VAE impacts pulmonary circulation, respiratory and cardiac function, systemic inflammation and coagulation, often with serious or fatal consequences. When VAE enters arterial circulation, air emboli affect cerebral blood flow and the central nervous system. New medical devices remove air from intravenous infusions. Early recognition and treatment reduce the clinical sequelae of VAE. An organized team approach to treatment including clinical simulation can facilitate preparedness for VAE. The MAUDE database included 416 injuries and 95 fatalities from VAE. Data from the American Society of Anesthesiologists Closed Claims Project showed 100% of claims for VAE resulted in a median payment of $325,000.

CONCLUSIONS

VAE is an important and underappreciated complication of surgery, anesthesia and medical procedures.

Sodium nitroprusside in 2014: A clinical concepts review

Sodium nitroprusside has been used in clinical practice as an arterial and venous vasodilator for 40 years. This prodrug reacts with physiologic sulfhydryl groups to release nitric oxide, causing rapid vasodilation, and acutely lowering blood pressure. It is used clinically in cardiac surgery, hypertensive crises, heart failure, vascular surgery, pediatric surgery, and other acute hemodynamic applications. In some practices, newer agents have replaced nitroprusside, either because they are more effective or because they have a more favorable side-effect profile. However, valid and adequately-powered efficacy studies are sparse and do not identify a superior agent for all indications. The cyanide anion release concurrent with nitroprusside administration is associated with potential cyanide accumulation and severe toxicity. Agents to ameliorate the untoward effects of cyanide are limited by various problems in their practicality and effectiveness. A new orally bioavailable antidote is sodium sulfanegen, which shows promise in reversing this toxicity. The unique effectiveness of nitroprusside as a titratable agent capable of rapid blood pressure control will likely maintain its utilization in clinical practice for the foreseeable future. Additional research will refine and perhaps expand indications for nitroprusside, while parallel investigation continues to develop effective antidotes for cyanide poisoning.

The normalization of deviance: do we (un)knowingly accept doing the wrong thing?

There are many elements that contribute to errors within an industry or profession. Several human factors associated with safety breakdowns are outlined in Table 2. Experience and root-cause analyses usually document that 2 or more of these factors coalesce to form a "perfect storm" leading to a mishap. For example, expecting a fatigued provider to care for an emergency patient with concurrent production pressure to maintain the elective schedule, while using new and unfamiliar equipment, is a potent mix of risk factors. As Gaba et al. pointed out, production pressure "is a reality for many anesthesiologists and is perceived in some cases to have resulted in unsafe actions." One solution is to integrate standard protocols and expectations for safe practice and expected behavior throughout the practice. Other potential solutions may involve the design of better and "smarter" monitors that will reduce the noise pollution and attendant distractions in the OR, and variable priority training that helps clinicians focus on "optimal distribution of attention when performing multiple tasks simultaneously with the goal of flexible allocation of attention." We have also observed the phenomenon of intersecting curves of knowledge versus experience. When we exit our organized training period, our knowledge base is strong. We have studied for specialty examinations, experienced the idealized purity of an academic environment, and have been taught the "right way" to practice by our mentors and role models. As the years pass, our minute, detailed knowledge may decrease, but our practical experience increases greatly, and patient care and safety are assured. However, as we are increasingly challenged to "do more with less," the temptation will arise to "cut a few comers" where we can to achieve productivity and efficiency benchmarks. To that end, we caution our colleagues to avoid the slippery slope of accepting a decrease in vigilance and safety while striving for "faster, better, cheaper." We encourage every individual to maintain vigilance, advocate for patient safety, aim for excellence and efficiency, and avoid the temptation of normalizing deviance from accepted safety standards.

A tale of two stents: perioperative management of patients with drug-eluting coronary stents

Drug-eluting stents were introduced into clinical practice to decrease coronary stent restenosis rates. Though remarkably effective in reducing this complication, recent data reveal that drug-eluting stents pose a significant risk for late stent thrombosis, an event strongly correlated with discontinuation of anti-platelet therapy. Because anti-platelet agents are often discontinued perioperatively, patients with DES are at risk for perioperative stent thrombosis and myocardial infarction. Along with a review of the recent literature, we present two cases of patients with drug-eluting stents scheduled for renal transplantation. Two distinct antithrombotic management strategies illustrate the risk of either approach-bleeding and transfusion versus stent thrombosis and myocardial infarction.

Men Are More Susceptible Than Women to Direct Pressure on Unmyelinated Ulnar Nerve Fibers

Ulnar nerve injury, the most common form of perioperative peripheral nerve injury, has a 3:1 male/female predominance. Neither the mechanism of perioperative ulnar nerve injury nor the reasons for the increased male susceptibility are well understood. We used an experimental model with arm flexion at the elbow, direct pressure on the ulnar nerve, and arm ischemia as distinct stress mechanisms to induce adverse changes in ulnar current perception thresholds (CPTs) on 3 groups of 40 male and 40 female volunteers (a total of 240 volunteers). CPT measurements were repeated at 2000-, 250-, and 5-Hz stimulating frequencies, specific to A-beta, A-delta, and unmyelinated C-fibers, respectively. Ischemia produced significant increases in CPT with all three stimulating frequencies, and there were no detectable differences between men and women. Flexion failed to produce significant CPT increases at any of the three stimulating frequencies, with no sex-based differences. Direct pressure produced significant CPT increases at 5 and 250 Hz, indicating inhibition of both unmyelinated C-fibers and myelinated A-delta fibers. C-fibers, but not A-delta fibers, demonstrated sex differences with direct pressure; there was a 1.7-fold (95% confidence interval, 1.2- to 2.4-fold) greater effect in men. Ischemia significantly inhibited the function of all three fiber types, perhaps sufficient to overwhelm gender differences.

IMPLICATIONS

The ability of direct pressure to produce a greater inhibition of unmyelinated C-fibers in male subjects compared with female subjects is consistent with, and may help explain, the male increased susceptibility to perioperative ulnar nerve dysfunction.

Comparison of a prototype esophageal oximetry probe with two conventional digital pulse oximetry monitors in aortocoronary bypass patients

OBJECTIVE

Pulse oximetry (SpO2) is the non-invasive standard for monitoring arterial oxygen saturation in patients undergoing anesthesia, but is subject to external interference by motion artifact, peripheral vasoconstriction, and low cardiac output. We hypothesized that oximetry signals could be acquired from the esophagus when peripheral pulse oximetry is unobtainable. Therefore, we tested an esophageal stethoscope which incorporates transverse oximetry photodetectors and emitters in patients undergoing coronary bypass surgery.

METHODS

Immediately after induction of general anesthesia in 10 coronary artery bypass (CABG) patients, Criticare and Nellcor digital probes were positioned on the left hand, concurrent with placement of an esophageal SpO2 probe. A computer recorded 5,910 matched oximetry signals every 15 sec during an average of 2.5 hrs. All SpO2 measurements were before, and immediately after non-pulsatile, hypothermic cardiopulmonary bypass. Data represent the percentage (median value [range]) of the total monitored time that a SpO2 value was displayed.

RESULTS

The Nellcor (99.8%, range 6.5-100%) and Criticare (99.7%, range 36.6-100%) acquired and displayed saturation signals more frequently (p = 0.003) than the esophageal monitor (75.3%, range 42.1-95.8%). The two standard digital oximeters had a mean difference of 0.9%, with a standard deviation of the differences of 0.9. The esophageal probe had a mean difference of -5.2% and -4.8%, with standard deviation of differences of 8.0 and 7.7 (compared to the Nellcor and Criticare monitors, respectively). A second-generation prototype shielded from electrocautery interference was tested in an additional 4 patients. The shielded prototype displayed signals more frequently (96.7%, range 68.4-100%) than the original esophageal prototype.

CONCLUSIONS

Digital pulse oximetry failure is common in CABG patients, probably because of marginal cardiac output and peripheral vasoconstriction associated with hypothermia. Our study could not confirm that esophageal technology, which utilizes the esophagus as a site of transflectance oximetry, was superior to conventional digital pulse oximetry.

Rapid disappearance of protamine in adults undergoing cardiac operation with cardiopulmonary bypass

BACKGROUND

Despite long use of protamine in cardiac operations, neither protamine concentrations nor pharmacokinetics have been reported in patients.

METHODS

Twenty-eight patients (age, 26 to 80 years) undergoing various cardiac surgical procedures gave their consent to receive 250 mg of protamine sulfate administered intravenously by an infusion pump during 5 minutes. Protamine was administered at the usual intraoperative time after separation from cardiopulmonary bypass for reversal of heparin. Timed arterial blood samples were obtained after protamine infusion. Blood plasma was subjected to solid-phase extraction and high-performance liquid chromatography. Total (free + heparin-bound) protamine concentration versus time data were subjected to pharmacokinetic modeling.

RESULTS

Twenty-six patients completed the study. Total plasma protamine concentrations declined rapidly. Model-independent pharmacokinetic analysis revealed median (range) values as follows: volume of distribution, 5.4 L (0.82 to 34 L); clearance, 1.4 L/min (0.61 to 3.8 L/min); and half-life, 4.5 min (1.9 to 18 min). Schwarz-Bayesian criterion identified a two-compartment exponential model with adjustment for weight in the central compartment volume of distribution as performing better than other compartmental or Michaelis-Menten models.

CONCLUSIONS

Protamine has a very short (approximately 5 minutes) half-life after a single 250-mg dose in adult patients. This short half-life could underlie recurrent anticoagulation after initial apparent reversal of heparin.

Dexmedetomidine-induced sedation in volunteers decreases regional and global cerebral blood flow

Dexmedetomidine is a selective alpha(2)-agonist approved for sedation of critically ill patients. There is little information on the effects of dexmedetomidine on cerebral blood flow (CBF) or intracranial hemodynamics, despite considerable other pharmacodynamic data. We hypothesized that therapeutic doses of dexmedetomidine would decrease CBF. Therefore, nine supine volunteers, aged 24-48 yr, were infused with a 1 micro g/kg IV loading dose of dexmedetomidine, followed by an infusion of 0.2 micro g. kg(-1). h(-1) (LOW DEX) and 0.6 micro g. kg(-1). h(-1) (HIGH DEX). Hemodynamic and CBF (via positron emission tomography) measurements were determined at each experimental time point. Dexmedetomidine decreased both cardiac output and heart rate during and 30 min after drug administration. Blood pressure decreased from 12% to 16% during and after the dexmedetomidine administration. Global CBF was decreased significantly from baseline (91 mL. 100 g(-1). min(-1) [95% confidence interval, 72-114] to 64 mL. 100 g(-1). min(-1) [51-81] LOW DEX and 61 mL. 100 g(-1). min(-1) [48-76] HIGH DEX). This decrease in CBF remained constant for at least 30 min after the dexmedetomidine infusion was discontinued, despite the plasma dexmedetomidine concentration decreasing 40% during this same time period (628 pg/mL [524-732] to 380 pg/mL [253-507]).

IMPLICATIONS

Dexmedetomidine-induced sedation decreased cerebral blood flow (CBF) by congruent with 33%, which could be due to direct alpha(2)-receptor cerebral smooth muscle vasoconstriction or to compensatory CBF changes caused by dexmedetomidine-induced decreases in the cerebral metabolic rate.

Ulnar nerve injury and perioperative arm positioning

Primum non nocere. Hippocrates included this admonition in Epidemics, Book I, Second Constitution, to do good or "to do no harm." However, even the most conscientious health care provider will encounter unexpected and serious adverse medical events. This discussion focuses on one relatively common, often perplexing, and usually unexplained perioperative complication: ulnar neuropathy. Perioperative ulnar neuropathy has received increased scientific attention because it accounts for one third of all nerve injury claims in the American Society of Anesthesiologists (ASA) Closed Claims Study database. In addition, these injuries may result in chronic pain or paresthesia, employment disability, catastrophic economic damages, and malpractice litigation. We will explore the current understanding of perioperative ulnar nerve dysfunction by summarizing the relevant scientific literature and information within the ASA closed-claims database, describing the epidemiologic features of perioperative nerve injuries, discussing relevant clinical investigations and recommendations for safe arm positioning during anesthesia, and reviewing the medico-legal issues inevitably intertwined with this topic, particularly the doctrine of res ipsa loquitur.

Clevidipine in adult cardiac surgical patients: a dose-finding study

BACKGROUND

Treatment of elevated blood pressure is frequently necessary after cardiac surgery to minimize postoperative bleeding and to attenuate afterload changes associated with hypertension. The purpose of this study was to investigate the pharmacodynamics and pharmacokinetics of a short-acting calcium channel antagonist, clevidipine, in the treatment of hypertension in postoperative cardiac surgical patients.

METHODS

Postoperative cardiac surgical patients were randomized to receive placebo or one of six doses of clevidipine. Hemodynamic parameters were recorded and blood samples were drawn for determination of clevidipine plasma concentrations during infusion and after discontinuation of clevidipine. The concentration-response relation was analyzed using logistic regression, and pharmacokinetic models were applied to the data using population analysis.

RESULTS

There were significant decreases in mean arterial blood pressure and systemic vascular resistance at doses greater than or equal to 1.37 microg. kg-1. min-1. There were no changes in heart rate, central venous pressure, pulmonary artery occlusion pressure, or cardiac index with increasing doses of clevidipine. The clevidipine C50 value for a 10% or greater decrease in mean arterial pressure was 9.7 microg/l and for a 20% or greater decrease in mean arterial pressure was 26.3 microg/l. The pharmacokinetics of clevidipine were best described with a three-compartment model with a volume of distribution of 32.4 l and clearance of 4.3 l/min. The early phase of drug disposition had a half-life of 0.6 min. The context-sensitive half-time is less than 2 min for up to 12 h of administration.

CONCLUSION

Clevidipine is a calcium channel antagonist with a very short duration of action that effectively decreases systemic vascular resistance and mean arterial pressure without changing heart rate, cardiac index, or cardiac filling pressures.

Benzodiazepines in the intensive care unit

The effects of BZ drugs result from interaction at the GABAA receptor within the CNS, producing anxiolysis, hypnosis, and amnesia in a dose-dependent fashion. These sedative effects are best titrated to reproducible clinical endpoints, using scoring systems such as the Ramsay scale. All BZs exhibit similar pharmacologic effects, but the important differences in pharmacokinetics and pharmacodynamics should be recognized to use these drugs safely and effectively within the ICU. Diazepam is the classic anxiolytic, amnestic, and sedative agent, but the presence of long-acting active metabolites that depend on the kidneys for elimination limits its use in many ICU patients. Lorazepam is the most potent BZ used in the ICU; it has stable pharmacokinetics and relatively low cost. This drug is best reserved for situations in which rapid onset is not essential and long-term sedation is anticipated. Midazolam has the shortest t1/2 of the commonly used BZs, generates few active metabolites, and is water soluble at physiologic pH. Thus, it is well suited for continuous infusion in the ICU, and the recent introduction of generic formulations of midazolam has decreased the drug-acquisition cost for many hospitals. Optimal sedation for ICU patients often requires BZ and concomitant therapy with drugs such as haloperidol, dexmedetomidine, opioids, and so forth, to reduce untoward side effects and, perhaps, overall drug costs. Flumazenil, a specific BZ antagonist, can be used for diagnostic or therapeutic reversal of BZ agonists when appropriate. Most experienced intensivists recommend an individualized approach to sedation and titration of anxiolysis to maximize efficacy, minimize side effects, and optimize cost effectiveness in the ICU. New CNS monitors of the EEG, such as the BIS or entropy EEG monitors, may refine titration algorithms further in the near future.

Reduced regional and global cerebral blood flow during fenoldopam-induced hypotension in volunteers

Dopamine has a wide spectrum of receptor and pharmacologic actions that may affect cerebral blood flow (CBF). A new, selective dopamine-1 agonist, fenoldopam, is a potent systemic vasodilator with moderate alpha(2)-receptor affinity. However, the effects of fenoldopam on the cerebral circulation are undefined. We therefore hypothesized that infusion of fenoldopam would decrease mean arterial blood pressure (MAP) and might concurrently decrease CBF via vascular alpha(2)-adrenoreceptor activation in awake volunteers. We studied nine healthy normotensive subjects, using positron emission tomography to measure CBF in multiple cortical and subcortical regions of interest. In addition, bioimpedance cardiac output and middle cerebral artery blood flow velocity were determined during fenoldopam-induced hypotension. Three men and four women, aged 25-43 yr, completed the study. Fenoldopam infused at 1.3 +/- 0.4 microg. kg(-1). min(-1) (mean +/- SD) reduced MAP 16% from baseline: from 94 (89-100) mm Hg (mean [95% confidence interval]) to 79 [74-85] mm Hg (P < 0.0001). During the fenoldopam infusion, both cardiac output (+39%), and heart rate (+45%) increased significantly, whereas global CBF decreased from baseline, 45.6 [35.6-58.5] mL. 100 g(-1). min(-1), to 37.7 [33.9-42.0] mL. 100 g(-1). min(-1) (P < 0.0001). Despite restoration of baseline MAP with a concurrent infusion of phenylephrine, global CBF remained decreased relative to baseline values at 37.9 [34.0-42.3] mL. 100 gm(-1). min(-1) (P < 0.0001). Changes in middle cerebral artery velocity did not correlate with positron emission tomography-measured changes of CBF induced by fenoldopam, with or without concurrent phenylephrine.

IMPLICATIONS

In awake volunteers with (presumably) intact cerebral autoregulation,fenoldopam-induced hypotension significantly decreased global cerebral bloodflow (CBF). Clinicians should be aware of these pharmacodynamic effects when choosing a vasodilator to control blood pressure, especially in situations where control of CBF, cerebral blood volume, and intracranial pressure are therapeutic priorities.