Double lumen endobronchial tube intubation: lessons learned from anatomy.

BACKGROUND: Double lumen endobronchial tubes (DLTs) are frequently used to employ single lung ventilation strategies during thoracic surgical procedures. Placement of these tubes can be challenging even for experienced clinicians. We hypothesized that airway anatomy, particularly of the glottis and proximal trachea, significantly impacts the ease or difficulty in placement of these tubes. METHODS: Images from 24 randomly selected Positron Emission Tomography - Computed Tomography (PET-CT) scans were evaluated for several anatomic aspects of the upper airway, including size and angulation of the glottis and proximal tracheal using calibrated CT measurements and an online digital protractor. The anatomic issues identified were confirmed in cadaveric anatomic models. RESULTS: Proximal tracheal diameter measurements in PET-CT scans demonstrated a mean ± standard deviation of 20.4 ± 2.5 mm in 12 males and 15.5 ± 0.98 mm in 12 females (p < 0.001), and both were large enough to accommodate 39 French and 37 French DLTs in males and females, respectively. Subsequent measurements of the posterior angulation of the proximal trachea revealed a mean angle of 40.8 ± 5.7 degrees with no sex differences. By combining the 24 individual posterior tracheal angles with the 16 angled distal tip measurements DLTs (mean angle 24.9 ± 2.1 degrees), we created a series of 384 patient intubation angle scenarios. This data clearly showed that DLT rotation to a full 180 degrees decreased the mean intubation angle between the DLT and the proximal trachea from a mean of 66.6 ± 5.9 to only 15.8 ± 5.9 degrees. CONCLUSIONS: Rotation of DLTs a full 180 instead of the recommended 90 degrees facilitates DLT intubations.

Research and development of the sOLVe Tube™ dual lumen endobronchial tube: from concept to construct.

Introduction: Dual lumen endobronchial tubes (DLTs) are frequently used for lung isolation and one lung ventilation in thoracic surgery and other specialized clinical scenarios. Modern DLTs are large and rigid, and account for half of all tracheobronchial injuries. Their 70 year old design has numerous flaws which limit their safety and clinical utility. Our research team set out to design a new and improved DLT to mitigate these shortcomings, and then test the proposed device to ensure proper function. Methods: Using published airway anatomy data and computed tomography imaging from 195 thoracic surgery patients, we designed a new DLT with a single size/configuration that would fit into adult surgery patients. This single "Universal design" was intended to replace both left and right sided 35Fr-41Fr DLTs (8 total products), while remaining small in diameter (35Fr). Other design goals included: 1) making intubation easier and safer, 2) allowing full sized therapeutic bronchoscopes to fit into this tube, 3) making the DLT more resistant to dislodgement. After design process completion the proposed dimensions were tested against 195 patients' left and right mainstem bronchi for radiographic fit. Once production prototypes were manufactured, they were tested in large adult Yorkshire pigs and fresh human cadavers for anatomic fit and performance. Results: The proposed design passed the radiographic fit test in all 195 patients for both left and right mainstem endobronchial placement. Intubation was successful and deemed atraumatic in all pigs and cadavers, and the device appropriately fit in both the right and left mainstem bronchi. Lung isolation was successfully achieved and the device proved resistant to axial force dislodgement. Conclusion: We propose a new design for a novel DLT meant to replace 8 currently supplied adult configurations with a single, one size/configuration fits all product that allows for large bore bronchoscopy and resists axial force dislodgement.

Proof-of-concept study of compartmentalized lung ventilation using system for asymmetric flow regulation (SAFR).

Asymmetrical distribution of acute lung injury in mechanically ventilated patients can result in a heterogeneity of gas distribution between different regions, potentially worsening ventilation-perfusion matching. Furthermore, overdistension of healthier, more compliant lung regions can lead to barotrauma and limit the effect of increased PEEP on lung recruitment. We propose a System for Asymmetric Flow Regulation (SAFR) which, combined with a novel double lumen endobronchial tube (DLT) may offer individualized lung ventilation to the left and right lungs, better matching each lung's mechanics and pathophysiology. In this preclinical experimental model, the performance of SAFR on gas distribution in a two-lung simulation system was tested. Our results indicate that SAFR may be a technically feasible and potentially clinically useful although further research is warranted.

A novel negative pressure isolation device reduces aerosol exposure: A randomized controlled trial.

Background and aim: The COVID-19 pandemic has led to a proliferation of intubation barriers designed to protect healthcare workers from infection. We developed the Suction-Assisted Local Aerosol Containment Chamber (SLACC) and tested it in the operating room. The primary objectives were to determine the ease and safety of airway management with SLACC, and to measure its efficacy of aerosol containment to determine if it significantly reduces exposure to health care workers. Methods: In this randomized clinical trial, adult patients scheduled to undergo elective surgery with general endotracheal anesthesia were screened and informed consent obtained from those willing to participate. Patients were randomized to airway management either with or without the SLACC device. Patients inhaled nebulized saline before and during anesthesia induction to simulate the size and concentration of particles seen with severe symptomatic SARS-CoV-2 infection. Results: 79 patients were enrolled and randomized. Particle number concentration (PNC) at the patients' and healthcare workers' locations were measured and compared between the SLACC vs. control groups during airway management. Ease and success of tracheal intubation were recorded for each patient. All intubations were successful and time to intubation was similar between the two groups. Healthcare workers were exposed to significantly lower particle number concentrations (#/cm3) during airway management when SLACC was utilized vs. control. The particle count outside SLACC was reduced by 97% compared to that inside the device. Conclusions: The SLACC device does not interfere with airway management and significantly reduces healthcare worker exposure to aerosolized particles during airway management.

Minimally Invasive Bilateral Stellate Ganglionectomy for Refractory Ventricular Tachycardia.

Cardiac sympathetic denervation (CSD) for refractory ventricular tachycardia (VT) has been shown to decrease VT recurrence and defibrillator shocks in patients with ischemic and nonischemic cardiomyopathy. Here and in the accompanying Video, we demonstrate the technique for minimally invasive CSD, highlight important technical points, and report surgical outcomes. CSD is accomplished through bilateral resection of the inferior one-third to one-half of the stellate ganglion en bloc with T2-T4 sympathectomy. Despite the high potential for perioperative risk, most patients do not have serious complications. We find that surgical CSD can be performed safely in an attempt to liberate patients from refractory VT.

Minimally Invasive Bilateral Stellate Ganglionectomy for Refractory Ventricular Tachycardia.

Cardiac sympathetic denervation (CSD) for refractory ventricular tachycardia (VT) has been shown to decrease VT recurrence and defibrillator shocks in patients with ischemic and nonischemic cardiomyopathy. Here and in the accompanying Video, we demonstrate the technique for minimally invasive CSD, highlight important technical points, and report surgical outcomes. CSD is accomplished through bilateral resection of the inferior one-third to one-half of the stellate ganglion en bloc with T2-T4 sympathectomy. Despite the high potential for perioperative risk, most patients do not have serious complications. We find that surgical CSD can be performed safely in an attempt to liberate patients from refractory VT.

Recurrent ventricular tachycardia after cardiac sympathetic denervation: Prolonged cycle length with improved hemodynamic tolerance and ablation outcomes.

INTRODUCTION: Cardiac sympathetic denervation (CSD) is utilized for the management of ventricular tachycardia (VT) in structural heart disease when refractory to radiofrequency ablation (RFA) or when patient/VT characteristics are not conducive to RFA. METHODS: We studied consecutive patients who underwent CSD at our institution from 2009 to 2018 with VT requiring repeat RFA post-CSD. Patient demographics, VT/procedural characteristics, and outcomes were assessed. RESULTS: Ninety-six patients had CSD, 16 patients underwent RFA for VT post-CSD. There were 15 male and 1 female patients with mean age of 54.2 ± 13.2 years. Fourteen patients had nonischemic cardiomyopathy. A mean of 2.0 ± 0.8 RFAs for VT was unsuccessful before the patient undergoing CSD. The median time between CSD and RFA was 104 days (interquartile range [IQR] = 15-241). The clinical VT cycle length was significantly increased after CSD both spontaneously on ECG and/or ICD interrogation (355 ± 73 ms pre-CSD vs. 422 ± 94 ms post-CSD, p = .001) and intraprocedurally (406 ± 86 ms pre-CSD vs. 457 ± 88 ms post-CSD, p = .03). Two patients had polymorphic and 14 had monomorphic VT (MMVT) pre-CSD, and all patients had MMVT post-CSD. The proportion of mappable, hemodynamically stable VTs increased from 35% during pre-CSD RFA to 58% during post-CSD RFA (p = .038). At median follow-up of 413 days (IQR = 43-1840) after RFA, eight patients had no further VT. CONCLUSION: RFA for recurrent MMVT post-CSD is a reasonable treatment option with intermediate-term clinical success in 50% of patients. Clinical VT cycle length was significantly increased after CSD with associated improvement in mappable, hemodynamically tolerated VT during RFA.

A Novel Negative Pressure Isolation Device for Aerosol Transmissible COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic creates a need to protect health care workers (HCWs) from patients undergoing aerosol-generating procedures which may transmit the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Existing personal containment devices (PCDs) may protect HCWs from respiratory droplets but not from potentially dangerous respiratory-generated aerosols. We describe a new PCD and its aerosol containment capabilities. The device ships flat and folds into a chamber. With its torso drape and protective arm sleeves mounted, it provides contact, droplet, and aerosol isolation during intubation and cardiopulmonary resuscitation (CPR). Significantly improved ergonomics, single-use workflow, and ease of removal distinguish this device from previously published designs.

Autonomic nervous system involvement in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a chronic pulmonary vascular disease characterized by increased pulmonary vascular resistance (PVR) leading to right ventricular (RV) failure. Autonomic nervous system involvement in the pathogenesis of PAH has been demonstrated several years ago, however the extent of this involvement is not fully understood. PAH is associated with increased sympathetic nervous system (SNS) activation, decreased heart rate variability, and presence of cardiac arrhythmias. There is also evidence for increased renin-angiotensin-aldosterone system (RAAS) activation in PAH patients associated with clinical worsening. Reduction of neurohormonal activation could be an effective therapeutic strategy for PAH. Although therapies targeting adrenergic receptors or RAAS signaling pathways have been shown to reverse cardiac remodeling and improve outcomes in experimental pulmonary hypertension (PH)-models, the effectiveness and safety of such treatments in clinical settings have been uncertain. Recently, novel direct methods such as cervical ganglion block, pulmonary artery denervation (PADN), and renal denervation have been employed to attenuate SNS activation in PAH. In this review, we intend to summarize the multiple aspects of autonomic nervous system involvement in PAH and overview the different pharmacological and invasive strategies used to target autonomic nervous system for the treatment of PAH.

Utilizing Forced Vital Capacity to Predict Low Lung Compliance and Select Intraoperative Tidal Volume During Thoracic Surgery.

BACKGROUND: Tidal volume selection during mechanical ventilation utilizes dogmatic formulas that only consider a patient's predicted body weight (PBW). In this study, we investigate whether forced vital capacity (FVC) (1) correlates better to total lung capacity (TLC) than PBW, (2) predicts low pulmonary compliance, and (3) provides an alternative method for tidal volume selection. METHODS: One hundred thirty thoracic surgery patients had their preoperative TLC calculated via 2 methods: (1) pulmonary function test (PFT; TLCPFT) and (2) computed tomography 3D reconstruction (TLCCT). We compared the correlation between TLC and PBW with the correlation between TLC and FVC to determine which was stronger. Dynamic pulmonary compliance was then calculated from intraoperative ventilator data and logistic regression models constructed to determine which clinical measure best predicted low compliance. Ratios of tidal volume/FVC plotted against peak inspiratory pressure were utilized to construct a new model for tidal volume selection. Calculated tidal volumes generated by this model were then compared with those generated by the standard lung-protective formula Vt = 7 cc/kg. RESULTS: The correlation between FVC and TLC (0.82 for TLCPFT and 0.76 for TLCCT) was stronger than the correlation between PBW and TLC (0.65 for TLCPFT and 0.58 for TLCCT). Patients with very low compliance had significantly smaller lung volumes (forced expiratory volume at 1 second, FVC, TLC) and lower diffusion capacity of the lungs for carbon monoxide when compared with patients with normal compliance. An FVC cutoff of 3470 cc was 100% sensitive and 51% specific for predicting low compliance. The proposed equation Vt = FVC/8 significantly reduced calculated tidal volume by a mean of 22.5% in patients with low pulmonary compliance without affecting the mean tidal volume in patients with normal compliance (mean difference 0.9%). CONCLUSIONS: FVC is more strongly correlated to TLC than PBW and a cutoff of about 3.5 L can be utilized to predict low pulmonary compliance. The equation Vt = FVC/8 reduced mean calculated tidal volume in patients with low pulmonary compliance and/or small lungs.

A Comparison of the Haider Tube-Guard® Endotracheal Tube Holder Versus Adhesive Tape to Determine if This Novel Device Can Reduce Endotracheal Tube Movement and Prevent Unplanned Extubation.

BACKGROUND: Endotracheal tube security is a critical safety issue. We compared the mobility of an in situ endotracheal tube secured with adhesive tape to the one secured with a new commercially available purpose-designed endotracheal tube-holder device (Haider Tube-Guard). We also observed for the incidence of oropharyngeal or facial trauma associated with the 2 tube fixation methods. METHODS: Thirty adult patients undergoing general anesthesia with neuromuscular blockade were prospectively enrolled. Immediately after intubation, a single study author positioned the endotracheal tube tip in the distal trachea using a bronchoscope. Anesthesiologists caring for patients secured the tube in their normal fashion (always with adhesive tape). A force transducer was used to apply linear force, increasing to 15 N or until the principal investigator deemed that the force be aborted for safety reasons. The displacement of the endotracheal tube was measured with the bronchoscope. Any tape was then removed and the endotracheal tube secured with the Haider Tube-Guard device. The linear force was reapplied and the displacement of the endotracheal tube measured. The Haider Tube-Guard device was left in place for the duration of the case. The patient's face and oropharynx were examined for any evidence of trauma during surgery and in the recovery room. On discharge from the postanesthesia care unit, the patient answered a brief survey assessing for any subjective evidence of minor facial or oropharyngeal trauma. RESULTS: Under standardized tension, the endotracheal tube withdrew a mean distance of 3.4 cm when secured with adhesive tape versus 0.3 cm when secured with the Haider Tube-Guard (P <0.001). Ninety-seven percent of patients (29/30) experienced clinically significant endotracheal tube movement (>1 cm) when adhesive tape was used to secure the tube versus 3% (1/30) when the Haider Tube-Guard was used (P <0.001). Thirty percent of patients (9/30) were potentially deemed a high extubation risk (endotracheal tube movement >4 cm) when the endotracheal tube was secured with tape versus 0% (0/30) when secured with the Haider Tube-Guard (P = 0.004). Six patients with taped endotracheal tubes required the traction to be aborted before 15 N of force was achieved to prevent potential extubation as the tape either separated from the face or stretched to allow excessive endotracheal tube movement. None of the patients appeared to sustain any injury from the Haider Tube-Guard device. CONCLUSIONS: The Haider Tube-Guard significantly reduced the mobility of the endotracheal tube when compared with adhesive tape and was well tolerated in our observations.

Acute vocal fold dystonic reaction to propofol: a case report.

A 67-year old male underwent uneventful robotic-assisted thoracoscopic resection of a solitary pulmonary fibrous tumor. Immediately following extubation at the completion of the surgical procedure, the patient developed respiratory distress that did not resolve with treatment. Benadryl provided only temporary relief. Midazolam and hydromorphone were given for anxiolysis and analgesia respectively, which provided transient relief of symptoms. Propofol was given to decrease upper airway reflexes. Adequate reversal from nondepolarizing neuromuscular blockade was confirmed with nerve stimulator. A flexible laryngoscope was introduced nasally to visualize the vocal cords, which revealed intermittent tremulousness of the vocal cords, adduction of bilateral vocal cords to the midline, and minimal to absent opening with inspiration, without any apparent injury or blood, saliva, or vomit noted in or around the glottic opening. The patient was then given diazepam and reintubated. Given the patient's history of difficulty breathing after previous surgery and the lack of vocal cord movement, dystonic reaction to propofol was suspected. The patient remained intubated for two hours in the post-anesthesia care unit before being extubated uneventfully.

Revised Cardiac Risk Index (RCRI) is a useful tool for evaluation of perioperative cardiac morbidity in kidney transplant recipients.

BACKGROUND: We evaluated a published Revised Cardiac Risk Index (RCRI) to determine if this preoperative cardiovascular risk stratification tool would be useful in the kidney transplant recipient population. METHODS: We identified all kidney transplants from 2005 to 2009 (n=1652) at our institution. We performed a detailed retrospective chart review of (a) all recipients who underwent preoperative coronary angiography (n=169) and (b) an age-matched and transplantation year-matched group who did not undergo coronary angiography (n=156). Charts were reviewed for the presence of specific preoperative cardiovascular risk factors and perioperative cardiovascular complications (as defined by RCRI plus elevation of troponin) from time of surgery to hospital discharge. The total number of risk factors for each patient was compared with the occurrence of postoperative cardiac complications to identify a possible association. RESULTS: The number of risk factors was highly predictive of cardiovascular complications (receiver operating characteristic area, 0.77; P<0.0001). History of coronary artery disease was most strongly associated (odds ratio, 20.59; confidence interval, 4.73-89.53; P=0.0001) and history of congestive heart failure was also significantly associated with cardiac complications (odds ratio, 2.95; confidence interval, 1.01-8.59; P=0.0475). CONCLUSION: The RCRI is a useful tool for cardiac risk stratification in kidney transplantation and could be used to develop protocols for intraoperative and postoperative care to minimize complications.

Positive end expiratory pressure during one-lung ventilation: selecting ideal patients and ventilator settings with the aim of improving arterial oxygenation.

The efficacy of positive end-expiratory pressure (PEEP) in treating intraoperative hypoxemia during one-lung ventilation (OLV) remains in question given conflicting results of prior studies. This study aims to (1) evaluate the efficacy of PEEP during OLV, (2) assess the utility of preoperative predictors of response to PEEP, and (3) explore optimal intraoperative settings that would maximize the effects of PEEP on oxygenation. Forty-one thoracic surgery patients from a single tertiary care university center were prospectively enrolled in this observational study. After induction of general anesthesia, a double-lumen endotracheal tube was fiberoptically positioned and OLV initiated. Intraoperatively, PEEP = 5 and 10 cm H(2)O were sequentially applied to the ventilated lung during OLV. Arterial oxygenation, cardiovascular performance parameters, and proposed perioperative variables that could predict or enhance response to PEEP were analysed. T-test and χ(2) tests were utilized for continuous and categorical variables, respectively. Multivariate analyses were carried out using a classification tree model of binary recursive partitioning. PEEP improved arterial oxygenation by ≥20% in 29% of patients (n = 12) and failed to do so in 71% (n = 29); however, no cardiovascular impact was noted. Among the proposed clinical predictors, only intraoperative tidal volume per kilogram differed significantly between responders to PEEP and non-responders (mean 6.6 vs. 5.7 ml/kg, P = 0.013); no preoperative variable predicted response to PEEP. A multivariate analysis did not yield a clinically significant model for predicting PEEP responsiveness. PEEP improved oxygenation in a subset of patients; larger, although still protective tidal volumes favored a positive response to PEEP. No preoperative variables, however, could be identified as reliable predictors for PEEP responders.

Unintentional subdural injection: a complication of neuraxial anesthesia/analgesia.

Unintentional subdural injection during neuraxial anesthesia/analgesia continues to be a challenge for anesthesiologists. This unusual complication is often poorly recognized, with the diagnosis made in retrospect, or not at all. The clinical presentation of these regional blocks can be heterogeneous, ranging from restricted, patchy, or unilateral sensory blockade all the way to extensive and even life-threatening motor and autonomic nervous system depression. Prompt diagnosis using clinical algorithms and radiographic imaging is crucial for the early discontinuation of the offending catheter. Supportive care is mandatory in cases involving severe depression of consciousness, motor function, and/or sympathetic tone.