Safety and Considerations of the Anaesthetic Management during Bronchoscopic Lung Volume Reduction Treatments.

BACKGROUND: Different bronchoscopic lung volume reduction approaches are available for a select group of patients with advanced COPD. General anaesthesia is the recommended method of sedation during these procedures. However, this patient population is at an increased risk of anaesthetic complications, and the best approach to general anaesthesia and mechanical ventilation is unknown. OBJECTIVES: The aims of this study were to describe the anaesthetic management techniques used during bronchoscopic lung volume reduction procedures and to investigate the number of anaesthesia-related events. METHODS: Data were retrospectively collected from all endobronchial valve and lung volume reduction coil procedures performed between January 2018 and March 2020 in our hospital. Primary outcomes measures were anaesthetic technique including airway management; ventilation mode and settings; and the incidence of anaesthesia-related events, classified as catastrophic, severe, significant, or moderate. RESULTS: 202 procedures were included. One procedure was performed under procedural sedation, 198 (98%) under general anaesthesia with endotracheal intubation, and 3 (1.5%) under general anaesthesia with laryngeal mask airway. Volume-controlled ventilation was used in 64% of the procedures and pressure-controlled in 36%. Patients were ventilated with a median respiration rate of 9.9 (IQR: 9.6-10.6) breaths per minute, mean tidal volume of 5.8 ± 1.4 mL/kg, and median inspiratory to expiratory (I:E) ratio of 1:2.8 (IQR: 1:2.1-1:3.2). No catastrophic anaesthesia-related events were observed. Hypotension was the most observed anaesthesia-related event. CONCLUSIONS: Despite the presence of advanced COPD, general anaesthesia and mechanical ventilation are well tolerated by patients undergoing endobronchial valve or lung volume reduction coil treatment. This is presumably strongly linked to the strict selection criteria. Other important considerations are using a low respiratory rate, low tidal volume, and high I:E ratio.

Hypotension during propofol sedation for colonoscopy: a retrospective exploratory analysis and meta-analysis.

BACKGROUND: Intraoperative and postoperative hypotension occur commonly and are associated with organ injury and poor outcomes. Changes in arterial blood pressure (BP) during procedural sedation are not well described. METHODS: Individual patient data from five trials of propofol sedation for colonoscopy and a clinical database were pooled and explored with logistic and linear regression. A literature search and focused meta-analysis compared the incidence of hypotension with propofol and alternative forms of procedural sedation. Hypotensive episodes were characterised by the original authors' definitions (typically systolic BP <90 mm Hg). RESULTS: In pooled individual patient data (n=939), 36% of procedures were associated with episodes of hypotension. Longer periods of propofol sedation and larger propofol doses were associated with longer-lasting and more-profound hypotension. Amongst 380 patients for whom individual BP measurements were available, 107 (28%) experienced systolic BP <90 mm Hg for >5 min, and in 89 (23%) the episodes exceeded 10 min. Meta-analysis of 18 RCTs identified an increased risk ratio for the development of hypotension in procedures where propofol was used compared with the use of etomidate (two studies; n=260; risk ratio [RR] 2.0 [95% confidence interval: 1.37-2.92]; P=0.0003), remimazolam (one study; n=384; RR 2.15 [1.61-2.87]; P=0.0001), midazolam (14 studies; n=2218; RR 1.46 [1.18-1.79]; P=0.0004), or all benzodiazepines (15 studies; n=2602; 1.67 [1.41-1.98]; P<0.00001). Hypotension was less likely with propofol than with dexmedetomidine (one study; n=60; RR 0.24 [0.09-0.62]; P=0.003). CONCLUSIONS: Hypotension is common during propofol sedation for colonoscopy and of a magnitude and duration associated with harm in surgical patients.

A New Oxygen Uptake Measurement Supporting Target Selection for Endobronchial Valve Treatment.

BACKGROUND: Adequate target lobe selection for endobronchial valve (EBV) treatment in patients with severe emphysema is essential for treatment success and can be based on emphysema destruction, lobar perfusion, lobar volume, and collateral ventilation. As some patients have >1 target lobe for EBV treatment, we were interested whether we could identify the least functional lobe. OBJECTIVES: The objective of this study was to investigate the relationship between endoscopic lobar measurement of oxygen uptake, lobar destruction, and vascular volume, and whether this could help in identifying the least functional lobe and thus optimal target for EBV treatment. METHOD: We prospectively included patients who were scheduled for EBV treatment in our hospital. A customized gas analysis setup was used to measure lobar O2 uptake after lobar balloon occlusion. Quantitative CT analysis was performed to assess the degree of emphysematous destruction and lobar arterial and venous volumes. RESULTS: Twenty-one (5 male/16 female) patients with emphysema (median age 63 years, FEV1 25% of predicted, residual volume 234% of predicted) were included, and 49 endoscopic lobar measurements were performed. A lower O2 uptake significantly correlated with a higher degree of emphysematous lobar destruction (Spearman's ρ: 0.39, p < 0.01), and lower arterial and venous vascular volumes of the lobes (-0.46 and -0.47, respectively; both p < 0.001). CONCLUSIONS: Endoscopic measurement of lobar O2 uptake is feasible in patients with emphysema. Measurement of lobar O2 uptake helped to identify the least functional lobe and can be used as additional tool for EBV target lobe selection.

Collateral Ventilation Measurement Using Chartis: Procedural Sedation vs General Anesthesia.

BACKGROUND: Absence of interlobar collateral ventilation is key to successful endobronchial valve treatment in patients with severe emphysema and can be functionally assessed by using the Chartis measurement. This system has been validated during spontaneous breathing, undergoing procedural sedation (PS), but can also be performed under general anesthesia. Performing the Chartis measurement under PS is often challenging because of coughing, mucus secretion, and difficulties in maintaining an adequate level of sedation. The objective of this study was to investigate whether there is a difference in Chartis measurement outcomes between PS and general anesthesia. METHODS: In this prospective study, patients underwent Chartis measurements under both PS and general anesthesia. Study outcomes were Chartis measurement duration, number of measurements, feasibility, and success rate. RESULTS: The study included 30 patients with severe emphysema (mean age, 62 years; median FEV1, 29% of predicted). Chartis measurement duration was significantly longer under PS than under general anesthesia (mean, 20.3 ± 4.2 min vs 15.1 ± 4.4 min; P < .001). There was no difference in the number (median [range]) of measurements performed (2 [1-3] for PS vs 1 [1-3] for general anesthesia; P = 1.00). Chartis measurement was more feasible during general anesthesia (median sum of all feasibility scores, 12 [range, 6-26] for PS vs 7 [5-13] for general anesthesia; P < .001). There was no statistical difference in success rate: 77% of PS cases vs 97% of general anesthesia cases (P = .07). CONCLUSIONS: This study found that Chartis measurement under general anesthesia is faster and more feasible to perform compared with performance with PS, without affecting measurement outcomes. TRIAL REGISTRATION: Clinicaltrials.gov; No. NCT03205826; URL: www.clinicaltrials.gov.

Pharmacodynamic Interaction of Remifentanil and Dexmedetomidine on Depth of Sedation and Tolerance of Laryngoscopy.

BACKGROUND: Dexmedetomidine is a sedative with modest analgesic efficacy, whereas remifentanil is an opioid analgesic with modest sedative potency. Synergy is often observed when sedative-hypnotics are combined with opioid analgesics in anesthetic practice. A three-phase crossover trial was conducted to study the pharmacodynamic interaction between remifentanil and dexmedetomidine. METHODS: After institutional review board approval, 30 age- and sex- stratified healthy volunteers were studied. The subjects received consecutive stepwise increasing target-controlled infusions of dexmedetomidine, remifentanil, and remifentanil with a fixed dexmedetomidine background concentration. Drug effects were measured using binary (yes or no) endpoints: no response to calling the subject by name, tolerance of shaking the patient while shouting the name ("shake and shout"), tolerance of deep trapezius squeeze, and tolerance of laryngoscopy. The drug effect was measured using the electroencephalogram-derived "Patient State Index." Pharmacokinetic-pharmacodynamic modeling related the administered dexmedetomidine and remifentanil concentration to these observed effects. RESULTS: The binary endpoints were correlated with dexmedetomidine concentrations, with increasing concentrations required for increasing stimulus intensity. Estimated model parameters for the dexmedetomidine EC50 were 2.1 [90% CI, 1.6 to 2.8], 9.2 [6.8 to 13], 24 [16 to 35], and 35 [23 to 56] ng/ml, respectively. Age was inversely correlated with dexmedetomidine EC50 for all four stimuli. Adding remifentanil did not increase the probability of tolerance of any of the stimuli. The cerebral drug effect as measured by the Patient State Index was best described by the Hierarchical interaction model with an estimated dexmedetomidine EC50 of 0.49 [0.20 to 0.99] ng/ml and remifentanil EC50 of 1.6 [0.87 to 2.7] ng/ml. CONCLUSIONS: Low dexmedetomidine concentrations (EC50 of 0.49 ng/ml) are required to induce sedation as measured by the Patient State Index. Sensitivity to dexmedetomidine increases with age. Despite falling asleep, the majority of subjects remained arousable by calling the subject's name, "shake and shout," or a trapezius squeeze, even when reaching supraclinical concentrations. Adding remifentanil does not alter the likelihood of response to graded stimuli.

Drug selection for ambulatory procedural sedation.

PURPOSE OF REVIEW: Ambulatory procedural sedation is used to relieve anxiety, pain and discomfort in a broad spectrum of patients during many types of diagnostic or therapeutic procedures. This review focuses on recent comparative studies of commonly used and new drugs for adult ambulatory sedation. RECENT FINDINGS: Midazolam and propofol are commonly used for ambulatory sedation. Their pharmacological properties offer many advantages and there is much experience with their use. Ketamine can be a useful addition to hypnotic drugs but the advantage of the use of ketofol (a mixture of propofol and ketamine) is, although often practiced, difficult to assess. Dexmedetomidine is a relatively new sedative drug and many studies suggest advantages. New findings about its effects, however, show that the hemodynamic consequences of the use of dexmedetomidine may last for several hours. New sedative drugs for procedural sedation are still being developed: remimazolam has many properties that would make it an ideal sedative and has been studied in a phase 3 study. SUMMARY: The properties that would constitute the ideal sedative have yet to be combined in one drug. The selection of the drugs used for ambulatory sedation depends on many factors such as procedure type, patient characteristics and the expectations of patients and the healthcare provider. Because of this, the literature cannot yet provide a definitive answer to the question which drug is best selected in a specific situation.