Combined Use of ECMO, Prone Positioning, and APRV in the Management of Severe COVID-19 Patients.

Background: Severe COVID-19-associated Acute Respiratory Distress Syndrome (ARDS) may warrant extracorporeal membrane oxygenation (ECMO). We evaluated the safety and physiologic changes in oxygenation and hemodynamic profile during ECMO, prone positioning, and the two modalities combined in patients receiving veno-venous (VV) ECMO. Methods: Cohort study of consecutive adult patients with COVID-19-associated ARDS requiring VV-ECMO, classified into three groups: ECMO support only; Prone positioning only; and Prone positioning during ECMO. We collected hemodynamic, respiratory and ventilation variables as follows: pre-treatment, 1, 6, and 24 h post-treatment, and documented treatment-related complications. On-treatment variables were compared with pre-treatment using one-sample paired t-test with Bonferroni correction. Results: Fourteen patients (mean age 48.1 [SD 9.3] years, male [100%]) received VV-ECMO. Of those, 10 patients had data during prone positioning alone and seven had data while proned on ECMO. While on ECMO, patients had improvement in oxygen saturation, PaO2/FiO2 ratio, and minute ventilation up to 24 h post-treatment. Vasopressor requirements increased with ECMO at 1 h and 24 h post-treatment. Prone positioning was not associated with clinically significant hemodynamic or respiratory changes, either alone or during ECMO support. All patients sustained deep tissue injuries, but only those on the face or chest were related to prone positioning. Three patients required cannula replacement. In-hospital mortality was 43%. Conclusions: VV-ECMO and prone positioning in patients with COVID-19 ARDS was overall well-tolerated; however, physiologic improvements were marginal, and patients sustained deep tissue injuries. Although this was a selected population with high mortality, our data call into question the benefits of these management modalities in this severe COVID-19 population.

Right heart thrombi (RHT) and clot in transit with concomitant PE management: Approach and considerations.

Right heart thrombi (RHT) continues to pose a clinical dilemma for multiple specialties and is especially concerning when present with concomitant pulmonary embolism (PE). Patients with PE and RHT are at an increased risk of poor outcomes compared to PE without RHT. Although the exact incidence of RHT is unknown, the increasing use of point-of-care ultrasound may lead to an increased detection and frequency of RHT. There are multiple treatment strategies available for RHT, including anticoagulation, systemic thrombolysis, and endovascular and surgical therapies. Given that these treatment strategies involve multiple medical specialties, the management of RHT with concomitant PE can be complex. Currently, there is limited clinical data and guidelines on the treatment and management of RHT. We aim to provide a review on RHT with concomitant PE, including risk stratification, treatment considerations, and our approach to the management of RHT.

Efficacy and Safety of Sugammadex to Shorten Time-to-Extubation Following Cardiac Surgery: A Single-Center Randomized Placebo-Controlled Trial.

Residual neuromuscular blockade (NMB) is an important and modifiable factor associated with prolonged mechanical ventilation after cardiac surgery. Studies evaluating the use of sugammadex for residual NMB reversal in the post-cardiac surgery ICU setting are lacking. We conducted a randomized trial to determine the efficacy of sugammadex in reducing time to extubation in patients admitted to the ICU after cardiac surgery. DESIGN: Single-center, randomized, double-blind, placebo-controlled trial. SETTING: University-based cardiothoracic ICU. SUBJECTS: Patients (n = 90) undergoing elective aortic valve replacement (AVR) and/or coronary artery bypass grafting (CABG) surgery. INTERVENTIONS: Participants were randomized to receive either sugammadex (2 mg/kg) or placebo after arrival to the ICU. MEASUREMENTS AND MAIN RESULTS: The primary study endpoint was time from study drug administration to extubation. Of the 90 patients included in the study (45 in each group), a total of 68 patients underwent CABG, 13 AVR, and nine combined AVR and CABG. Baseline characteristics and intraoperative anesthetic medications were comparable between groups. Patients in sugammadex group had reduced time to extubation compared with the placebo group (median [interquartile range (IQR)]-sugammadex group: 126.0 min [84.0-274.0 min] vs placebo: 219.0 min [121.0-323.0 min]; difference in means [95% CI], 72.8 [1.5-144.1 min]; p = 0.01. There were no differences in negative inspiratory force (mean [sd]-sugammadex group: 33.79 cm H2O [8.39 cm H2O] vs placebo: -31.11 cm H2O [7.17 cm H2O]) and vital capacity (median [IQR]-sugammadex group: 1.1 L [0.9-1.3 L] vs placebo: 1.0 L [0.9-1.2 L]). There were no differences between groups in postoperative blood product requirement, dysrhythmias, length of ICU, or hospital stay. There were no serious adverse events in either group. CONCLUSIONS: This randomized trial showed that the administration of sugammadex after cardiac surgery decreased time to extubation by approximately 1 hour. Larger trials may be required to confirm these findings and determine the clinical implications.

Aqueous Phase Behavior of a NaLAS-Polycarboxylate Polymer System.

Linear alkylbenzene sulfonate (NaLAS) surfactant is often combined with polycarboxylate polymers in detergent formulations. However, the behavior of these aqueous surfactant-polymer systems in the absence of an added electrolyte is unreported. This work investigates the behavior of such systems using polarized light microscopy, small-angle X-ray scattering (SAXS), centrifugation, and 2H NMR techniques. A phase diagram at 50 °C is reported for 0-50 wt % NaLAS concentrations and 0-10 wt % polycarboxylate concentrations. The NaLAS-water system is micellar at concentrations <35 wt %, and a 2-phase micellar-lamellar system is seen at higher NaLAS levels, consistent with that reported by previous studies. As polymers are added at low surfactant concentrations (∼10 to 20 wt % NaLAS), a second optically isotropic phase is formed; this is thought to be a polymer-rich phase. Further addition of polycarboxylate leads to the formation of a lamellar phase. At high surfactant concentrations (>20 wt % NaLAS), the addition of a polymer induces a second lamellar phase. These observed behaviors are thought to arise as a result of depletion flocculation and salting-out effects. The observed lamellar phases adopt colloidal multilamellar vesicle (MLV) structures, and the average MLV radii were estimated using 2H NMR by probing the diffusion and anisotropy of D2O within the bilayers of the vesicles. The NMR results show that as the polymer concentration was increased from 0 to 10 wt %, an increase in the average multilamellar vesicle size from ∼200 to ∼500 nm was observed. This increase in the calculated average MLV radius likely results from depletion flocculation-induced MLV fusion.

Association of red blood cell transfusion and short- and longer-term mortality after coronary artery bypass graft surgery.

OBJECTIVE: Red blood cell (RBC) transfusion has been linked to increased morbidity and mortality. However, strict RBC transfusion recommendations recently have been questioned. The aim of this study was to investigate the short- and long-term mortality outcomes after RBC transfusion in patients undergoing coronary artery bypass graft surgery (CABG). DESIGN: This was a retrospective medical record review. SETTING: Tertiary care academic medical center. PARTICIPANTS: The study included patients who underwent CABG from June 2006 to May 2013. INTERVENTION: Adult (>18 years) cardiac surgery patients who were admitted to the cardiothoracic intensive care unit in a tertiary care academic medical center from June 2006 to May 2013 were collected. In all, 2,180 patients who underwent CABG surgery were included into propensity-score matching analyses, which were matched 1:1. Patients who did not receive transfusion of packed red blood cells (PRBC) (n = 937) were compared with those who received 1 to 5 U (n = 1,113). The study outcomes included mortality rates at 1, 3, and 6 months (short-term) and 1, 2, 3, and 4 years (long-term). RESULTS: No statistical significant differences were found for the 1-month (2% v 1.1%, p = 0.292), 3-month (2.9% v 2%, p = 0.396), or 6-month mortality rate (4.3% v 3.4%, p = 0.602) in 446 patients with 1 to 5 U versus 446 matched patients with no PRBC transfusion. Patients in the transfused group compared with those in the no-transfusion group had statistically significant higher 3-year mortality rate (11% v 6.7%; hazard ratio, 1.64; 95% confidence interval, 1.03-2.63; p = 0.038). CONCLUSION: In the present study, patients undergoing CABG surgery and receiving <6 U of PRBC did not have statistically increased risk for in-hospital mortality and up to 2 years postoperatively. A modestly statistically significant difference was noted at 3 years. However, cumulatively, there was no statistical difference between the transfused and nontransfused groups at 4 years. Further studies are needed to confirm the findings and define the population that will benefit the most from blood transfusion.

Microfluidic SAXS Study of Lamellar and Multilamellar Vesicle Phases of Linear Sodium Alkylbenzenesulfonate Surfactant with Intrinsic Isomeric Distribution.

The structure and flow behavior of a concentrated aqueous solution (45 wt %) of the ubiquitous linear sodium alkylbenzenesulfonate (NaLAS) surfactant is investigated by microfluidic small-angle X-ray scattering (SAXS) at 70 °C. NaLAS is an intrinsically complex mixture of over 20 surfactant molecules, presenting coexisting micellar (L1) and lamellar (Lα) phases. Novel microfluidic devices were fabricated to ensure pressure and thermal resistance, ability to handle viscous fluids, and low SAXS background. Polarized light optical microscopy showed that the NaLAS solution exhibits wall slip in microchannels, with velocity profiles approaching plug flow. Microfluidic SAXS demonstrated the structural spatial heterogeneity of the system with a characteristic length scale of 50 nL. Using a statistical flow-SAXS analysis, we identified the micellar phase and multiple coexisting lamellar phases with a continuous distribution of d spacings between 37.5 and 39.5 Å. Additionally, we showed that the orientation of NaLAS lamellar phases is strongly affected by a single microfluidic constriction. The bilayers align parallel to the velocity field upon entering a constriction and perpendicular to it upon exiting. On the other hand, multilamellar vesicle phases are not affected under the same flow conditions. Our results demonstrate that despite the compositional complexity inherent to NaLAS, microfluidic SAXS can rigorously elucidate its structure and flow response.

The relationship between the photoplethysmographic waveform and systemic vascular resistance.

OBJECTIVE: The objective of this study was to determine the relationship between systemic vascular resistance (SVR), finger & ear photoplethysmographic measurements in 14 adult patients undergoing coronary artery bypass grafting (CABG). METHODS: Patients were monitored with photoplethysmographs of the finger and ear and continuous cardiac output (QT) via thermodilution catheter. The relationship between SVR, finger plethysmographic amplitude, width and ear plethysmographic amplitude, width was assessed with linear regression. RESULTS: The finger plethysmographic amplitude had a low correlation r value = -0.15, while finger plethysmographic width had a better correlation r value = 0.56. The correlation between SVR and ear plethysmographic amplitude and width were -0.24 and 0.62 respectively. Using receiver operating characteristic analysis the ear plethysmographic width had both better sensitivity and specificity than the finger plethysmographic width in identifying high and low SVR. Using a multiple regression analysis, SVR was estimated from the pulse oximeter waveforms: SVR calculated = 27.27 + (3978.53 x Ear pulse oximeter width) - (8.91 x Ear pulse oximeter area) + (1986.3 x Finger pulse oximeter width). Bland-Altman analysis was used the bias was 29.8 dynes s cm(-5), standard deviation was 587.3, upper and lower limit of agreement were 1204.45, and -1144.8 dynes s cm(-5) respectively. CONCLUSION: The data indicate that pulse width of finger and ear plethysmographic tracing are more sensitive to changes in SVR than the other indices. An appreciation of changes in pulse width may provide valuable evidence with respect to changes in peripheral vascular tone.

Survey of anesthesiologists as to the value of prior ECG in a patient with nonspecific ST-T wave changes.

BACKGROUND: An abnormal ECG often must be assessed preoperatively in the absence of prior tracings. We surveyed anesthesiologists to determine if their concern about nonspecific ST-T (NSST) wave changes is influenced significantly by the availability of a prior ECG for comparison. METHODS: Forty-eight anesthesiologists rated their concern (O=none, 1=minor, 2=moderate, 3=marked) about a patient with an intermediate cardiac risk factor and new NSST, NSST of indeterminate duration (no old ECG for comparison), or old NSST. RESULTS: Concern for patients with more recent development of NSST was significantly greater for each of the interage comparisons; P=0.019 for new vs indeterminate, P=0.003 for new vs old, and P=0.008 for indeterminate vs old. This was associated with increased tendency to obtain cardiology consultation. CONCLUSIONS: The efficiency of preoperative assessment of patients with NSST on ECG would be improved by consistent availability of prior ECG tracings to enable determination of the newness of current findings.

Toxins.

Exposures to toxins are prevalent, frequently complicate surgical emergencies, and impact critical care. A fundamental understanding of pathophysiologic principles and management strategies is essential for the anesthesiologist frequently responsible for the acute care of patients who have toxicologic exposures. Given their pervasiveness and ability to confound the clinical presentations in the perioperative or intensive care setting, substances of abuse and asphyxiants warrant particular attention and a high degree of vigilance.

Preoperative beta-blocker use: is titration to a heart rate of 60 beats per minute a consistently attainable goal?

STUDY OBJECTIVE: To quantify the prevalence of perioperative beta-blocker use and its impact on preoperative and preinduction heart rate (HR), in light of the recent publication of specific recommendations regarding perioperative beta-blocker use and desired HR. DESIGN: Retrospective observational study in patients who underwent elective and coronary artery bypass graft (CABG) surgery between January 2001 and March 2002. SETTING: Tertiary-care teaching hospital. MEASUREMENTS: Percentage of eligible patients who received beta-blockers preoperatively and the impact of non-protocol-based beta-blocker therapy on preadmission and preinduction HR were recorded. Differences were assessed with unpaired t test and chi(2) analysis; P < .05 was considered significant, with corrections for multiple comparisons. RESULTS: Of the patients who underwent vascular surgery, 9 had documented prior beta-blocker intolerance. Of the remaining 172 patients, 94.8% had indication for perioperative beta-blocker use. However, only 47.7% of the eligible patients received beta-blockers. Of the 155 CABG patients, 74.2% were taking beta-blockers preoperatively. Only 29% of vascular patients and 32% of CABG patients who were receiving beta-blockers had HR less than 60 beats per minute (bpm) at preadmission. The mean preadmission HR in vascular surgery patients was 65.2 +/- 11 and 73.2 +/- 13.8 bpm in beta-blocker and non-beta-blocker patients, respectively (P = .0001). In CABG surgery patients, preadmission HR values were 64.2 +/- 13 and 76.1 +/- 12 bpm in beta-blocker and non-beta-blocker patients, respectively (P = .001). The preinduction HR subsequently increased in the beta-blocker as well as in the non-beta-blocker groups. CONCLUSION: Only half of the patients who qualify to receive preoperative beta-blockers by current recommendations actually receive them before noncardiac surgery, and the majority of these patients have preadmission and preinduction HR less than 60 bpm. Targeting beta-blocker therapy treatment to an HR less than 60 bpm may not be readily achievable in many patients.