Abcejo, Arnoley S.

Perioperative cardiac arrest (POCA) is a catastrophic complication that requires immediate recognition and correction of the underlying cause to improve patient outcomes. While the hypoxia, hypovolemia, hydrogen ions (acidosis), hypo-/hyperkalemia, and hypothermia (Hs) and toxins, tamponade (cardiac), tension pneumothorax, thrombosis (pulmonary), and thrombosis (coronary) (Ts) mnemonic is a valuable tool for rapid differential diagnosis, it does not cover all possible causes leading to POCA. To address this limitation, we propose using the preload-contractility-afterload-rate and rhythm (PCARR) construct to categorize POCA, which is comprehensive, systemic, and physiologically logical. We provide evidence for each component in the PCARR construct and emphasize that it complements the Hs and Ts mnemonic rather than replacing it. Furthermore, we discuss the significance of utilizing monitored variables such as electrocardiography, pulse oxygen saturation, end-tidal carbon dioxide, and blood pressure to identify clues to the underlying cause of POCA. To aid in investigating POCA causes, we suggest the Anesthetic care, Surgery, Echocardiography, Relevant Check and History (A-SERCH) list of actions. We recommend combining the Hs and Ts mnemonic, the PCARR construct, monitoring, and the A-SERCH list of actions in a rational manner to investigate POCA causes. These proposals require real-world testing to assess their feasibility.

Abstract Purpose A human cadaveric model combining standard lung protective mechanical ventilation and modified cardiac bypass techniques was developed to allow investigation into automated modes of detection of venous air emboli (VAE) prior to in vivo human or animal investigations. Methods In this study, in order to create an artificial cardiopulmonary circuit in a cadaver that could mimic VAE physiology, the direction of flow was reversed from conventional cardiac bypass. Saline was circulated in isolation through the heart and lungs as opposed to the peripheral organs by placing the venous cannula into the aorta and the arterial cannula into the inferior vena cava with selective ligation of other vessels. Results Mechanical ventilation and this reversed cardiac bypass scheme allowed preliminary detection of VAE independently but not in concert in our current simulation scheme due to pulmonary edema in the cadaver. A limited dissection approach was used initially followed by a radical exposure of the great vessels, and both proved feasible in terms of air signal detection. We used electrical impendence as a preliminary tool to validate detection in this cadaveric model however we theorize that it would work for echocardiographic, intravenous ultrasound or other novel modalities as well. Conclusion A cadaveric model allows monitoring technology development with reduced use of animal and conventional human testing.

Remimazolam is a novel ultrashort-acting benzodiazepine that produces sedation by acting as a positive allosteric modulator of the gamma-amino butyric acid-A receptor. Its high water solubility and metabolism via tissue esterases allow for a rapid onset of sedation/anesthesia and prompt arousal despite prolonged use. In addition, the effects of remimazolam can be reversed with flumazenil. This narrative review discusses the role of remimazolam in patients undergoing neurosurgical and neuroradiological procedures, specifically its role during awake craniotomies and compatibility with neuromonitoring. Considerations for remimazolam use in patients with neurological diseases are also highlighted. In addition, the impact of remimazolam on postoperative excitation, risk for postoperative delirium, and delayed neurocognitive recovery are discussed. Although there seems to be a clinical promise for remimazolam based on limited case studies and our own institutional experience of its use, further clinical investigation is warranted to understand the potential impact of remimazolam on surgical and neurological outcomes.

BACKGROUND: Patients with existing coronary artery stents are at an increased risk for major adverse cardiac events (MACEs) when undergoing noncardiac surgery (NCS). Although the use of antifibrinolytic (AF) therapy in NCS has significantly increased in the past decade, the relationship between perioperative AF use and its association with MACEs among patients with existing coronary artery stents has yet to be assessed. In this study, we aim to evaluate the association of MACEs in patients with existing coronary artery stents who receive perioperative AF therapy during orthopedic surgery. METHODS: A single-center retrospective cohort study was conducted in adult patients with existing coronary artery stents who underwent orthopedic surgery from 2008 to 2018. Two cohorts were established: patients with existing coronary artery stents who did not receive perioperative AF and patients with coronary artery stents who received perioperative AF. Associations between AF use and the primary outcome of MACEs within 30 days postoperatively and the secondary outcomes of thrombotic complications, excessive surgical bleeding, and intensive care unit (ICU) admissions were analyzed using logistic regression models. Inverse probability of treatment weighting was used to control for confounding. Secondary analyses examining the association between coronary stent type/timing and the outcomes of interest were performed using unadjusted logistic regression models. RESULTS: A total of 473 patients met study criteria, including 294 who did not receive AF and 179 patients who received AF. MACEs occurred in 15 (5.1%) patients who did not receive AF and 1 (0.6%) who received AF ( P = .007). In weighted analyses, no significant difference was found in patients who received AF with regard to MACEs (odds ratio [OR] = 0.13, 95% confidence interval [CI], 0.01-1.74, P = .12), thrombotic complications (OR = 1.19, 95% CI, 0.53-2.68, P = .68), or excessive surgical bleeding (OR = 0.13, 95% CI, 0.01-2.23, P = .16) compared to patients who did not receive AF. CONCLUSIONS: The results of this study are inconclusive whether an association exists between perioperative AF use in patients with coronary artery stents and the outcome of MACEs compared to patients who did not receive perioperative AF therapy. The authors acknowledge that the imprecise CI hinders the ability to definitively determine whether an association exists in the study population. Further large prospective studies, powered to detect differences in MACEs, are needed to assess the safety of perioperative AF in patients with existing coronary artery stents and to clarify the mechanism of perioperative MACEs in this high-risk population.

Abstract Introduction Calcinosis cutis is a condition characterized by pathologic calcium deposition into superficial dermal skin layers. It is often associated with an autoimmune disease. However, it may also occur after minor localized trauma and infection. Description of Problem We report a case of lumbar epidural placement of labor analgesia in a parturient with severe dystrophic calcinosis cutis without apparent complications. Clinical Solution We recommend fastidious optimization of epidural placement conditions for all patients who may be at high risk for neuraxial anesthesia, including consideration of ultrasound use, use of an experienced anesthesia provider for neuraxial placement, and placement in early labor. Additionally, judicious discussion of risks, benefits, and alternatives when obtaining informed consent is critical, ideally with the patient identified for a comprehensive visit in a preoperative obstetric anesthesia clinic before delivery.

OBJECTIVEThe sitting or semisitting position in neurosurgery allows for several technical advantages, including improved visualization of the surgical field. However, it has also been associated with an increased risk of venous air embolisms and positioning-related complications that limit its commonplace adoption. The authors report a large, single-center series of cervical spine procedures performed with patients in the sitting or prone position in order to assess the perceived risk of intraoperative and postoperative complications associated with the sitting position.METHODSNoninstrumented, single-level posterior cervical spine procedures performed with patients in the sitting/semisitting or prone position from 2000 to 2016 at a single institution were reviewed. Institutional abstraction tools (DataMart and Chart Plus) were used to collect data from the medical records. The two positions were compared with regard to preoperative factors, intraoperative variables, and postoperative outcomes. Multivariable logistic regression models were fitted for 30-day readmission, 30-day return to the operating room, and complication rates.RESULTSA total of 750 patients (sitting, n = 480; prone, n = 270) were analyzed. The median age was 53 years for those who underwent surgery in the prone position and 50 years for those who underwent surgery in the sitting position (IQRs 45–62 years and 43–60 years, respectively), and 35% of the patients were female. Sitting cases were associated with significantly longer anesthetic times (221 minutes [range 199–252 minutes] vs 205 minutes [range 179–254 minutes]) and operative times (126 minutes [range 101–163 minutes] vs 149 minutes [120–181 minutes]). Cardiorespiratory events in the postanesthesia care unit (PACU) were comparable between the two groups, with the exception of episodes of apnea (2.6% vs 0.6%, p = 0.041) and hypoventilation (4.4% vs 0.8%, p < 0.003), which were more frequent in the prone-position cohort. On multivariable analysis, the effect of the sitting versus the prone position was not significant for 30-day readmission (OR 0.77, 95% CI 0.34–1.71, p = 0.52) or reoperation (OR 0.71, 95% CI 0.31–1.60, p = 0.40). The sitting position was associated with lower odds of developing any complication (OR 0.31, 95% CI 0.16–0.62, p < 0.001).CONCLUSIONSBased on the intraoperative and postoperative complications chosen in this study, the sitting position confers a similar safety profile to the prone position. This can be explained by a more anatomic positioning accounting for reduced temporary neurological deficits and reduced PACU-associated hypoventilation noted in this series. Nevertheless, the findings may also reflect institutional familiarity, experience, and mastery of this position type, and outcomes may not reflect practices in general.

Venous air embolism (VAE) is a well-described phenomenon that may have life-threatening cardiopulmonary and neurological consequences. Accidental administration of air during resuscitation while using a rapid infuser is rare. Furthermore, there is a paucity of published data describing the intraoperative management of VAE during emergent nonseated neurological surgery. We report a 22-year-old previously healthy female who experienced a motor vehicle accident with severe facial and head trauma, and mixed subdural and epidural hematomas with an 8 mm midline shift. Computed tomography revealed significant air entrainment in the right heart and main pulmonary artery, with venous air tracking from the right axillary vein. Given her age, lack of preexisting cardiac comorbidities, hemodynamic stability, and critical cerebral herniation risk, further cardiac evaluation was deferred, and the patient was transferred to the operating room for emergent decompressive craniotomy. Intraoperatively, she experienced acute decrease in mean arterial pressure and end-expiratory carbon-dioxide with loss of pulse oximetry waveform concerning for obstructive VAE physiology. She was responsive to fluid resuscitation and epinephrine administration and did not experience any recurrence of obstructive VAE. This challenging case report describes positive neurologic and hemodynamic outcomes after resuscitation-associated VAE and cardiopulmonary collapse during emergency neurosurgery. Comprehensive evaluation of risk, urgency of procedure, and need for diagnostic monitoring and treatment should be personalized.