Canadian Journal of Anaesthesia

To report the anesthetic management of a parturient with a large intrathoracic tumour, presenting for Cesarean section. Clinical features: A 28-yr-old parturient, gravida l, presented at 33 weeks gestation with a one month history of increasing cough and dyspnea. A computed tomography scan demonstrated a large mass filling the right hemothorax, causing mediastinal displacement to the left and carinal compression. Both mainstem bronchi were compressed and there was near total obliteration of the lumens of the right lobar bronchi. A decision was taken to expedite delivery to allow for staging and treatment of her disease and Cesarean section was scheduled. She was seen in consultation and prescribed oxygen by nasal prongs, dextromethorphan for cough and ranitidine the evening before and the morning of surgery. A subarachnoid block was performed and a block to the upper thoracic dermatomes was achieved; surgery proceeded uneventfully with the patient’s head and upper body elevated about 15° from the supine. The patient was discharged to the medical oncology service for evaluation and treatment. Intrathoracic tumours are uncommon in pregnancy. The physiological changes of pregnancy may mask not only the initial presentation but also, even advanced intrathoracic disease. Regional anesthesia is the anesthetic of choice and is rarely contraindicated by maternal condition.

The effect of direct laryngoscopy using a Macintosh blade (MAC) vs GlideScope™ videolaryngoscopy using a Spectrum LoPro blade (GVL) on nociceptive stimulation has not been quantitatively studied. This study used the new nociception level (NOL) index to compare the nociceptive response induced by GVL or MAC during laryngoscopy with or without intubation. Patients underwent two laryngoscopies at four-minute intervals (L1, L2), one with GVL and the other with MAC (first randomization). A third laryngoscopy (L3) followed by tracheal intubation was performed four minutes after L2 (GVL or MAC, second randomization). Nociception was quantitatively assessed by NOL and standard hemodynamic parameters (heart rate [HR] and mean arterial pressure). For the crossover design, blade comparisons accounted for sequence and blade type. A possible carryover effect between laryngoscopies was assessed. In the 50 patients randomized, there was no carryover effect from one laryngoscopy to the next for all analyzed parameters. Nociception level index peak values were higher with MAC than GVL. Analysis of ΔNOL showed a lower nociceptive response with GVL for L1+L2 combined. Mean peak NOL values were significantly higher after L3+intubation than after L1+L2, for both GVL and MAC groups. Analysis of ΔHR values did not show a significant difference between GVL and MAC for any laryngoscopy. Laryngoscopy alone with GVL induces less nociception than with MAC. The NOL was more sensitive than HR at detecting nociceptive responses to MAC vs GVL. Additionally, and irrespective of which technique/blade was used, the combination of laryngoscopy + tracheal intubation produced a much greater nociceptive response than the laryngoscopy alone. www.clinicaltrials.gov (NCT03277872); registered 29 August 2017.

The optimal regional technique to control pain after breast cancer surgery remains unclear. We sought to synthesize available data from randomized controlled trials comparing pain-related outcomes following various regional techniques for major oncologic breast surgery. In a systematic review and network meta-analysis, we searched trials in PubMed, Embase Scopus, Medline, Cochrane Central and Google Scholar, from inception to 31 July 2020, for commonly used regional techniques. The primary outcome was the 24-hr resting pain score measured on a numerical rating score of 0–10. We used surface under the cumulative ranking curve (SUCRA) to establish the probability of an intervention ranking highest. The analysis was performed using the Bayesian random effects model, and effect sizes are reported as 95% credible interval (Crl). We conducted cluster-rank analysis by combining 24-hr pain ranking with 24-hr opioid use or incidence of postoperative nausea and vomiting. Seventy-nine randomized controlled trials containing 11 different interventions in 5,686 patients were included. The SUCRA values of the interventions for 24-hr resting pain score were continuous paravertebral block (0.83), serratus anterior plane block (0.76), continuous wound infusion (0.76), single-level paravertebral block (0.68), erector spinae plane block (0.59), modified pectoral block (0.49), intercostal block (0.45), multilevel paravertebral block (0.41), wound infiltration (0.33), no intervention (0.12), and placebo (0.08). When compared with placebo, the continuous paravertebral block (mean difference, 1.26; 95% Crl, 0.43 to 2.12) and serratus anterior plane block (mean difference, 1.12; 95% Crl, 0.32 to 1.9) had the highest estimated probability of decreasing 24-hr resting pain scores. Cluster ranking analysis combining 24-hr resting pain scores and opioid use showed that most regional analgesia techniques were more effective than no intervention or placebo. Nevertheless, wound infiltration and continuous wound infusion may be the least effective active interventions for reducing postoperative nausea and vomiting. Continuous paravertebral block and serratus anterior plane block had a high probability of reducing pain at 24 hr after major oncologic breast surgery. The certainty of evidence was moderate to very low. Future studies should compare different regional anesthesia techniques, including surgeon-administered techniques such as wound infiltration or catheters. Trials comparing active intervention with placebo are unlikely to change clinical practice. Study registration: PROSPERO (CRD42020198244); registered 19 October 2020.

A two-dimensional model of the factors relevant to difficult laryngoscopy was analysed mathematically to determine clinical implications and limitations. The model describes the space into which the “inevitable residual volume” of the tongue (that part remaining anterior to the blade at laryngoscopy) can be displaced to permit a view of the larynx. Four points are used: the tip of the upper incisors; a point on the anterior airway just above the larynx; the mid-point between the mandibular condyles and the internal mid-point of the symphysis. The number, F, was defined by a formula developed from their spacial relationships. Decreasing F values imply an increasing likelihood of difficult laryngoscopy. The analysis investigated the effects of: translation of individual points; plotting individual point positions for specified F-values; translating adjacent pairs of points; treating any three points as a triangle which rotates about each of its apices; and lastly, translating three points independently. During manipulations the model behaved well mathematically. Single point analysis implied that jaw recession and a non-protruding mandible were comparable in effect. Closing the mouth around the laryngoscope blade maximised F-values. Prominence of the maxilla required greater forward displacement than backward movement of the symphysis for equivalent F-value change. One particular triangular rotation suggested an entirely novel mechanism for difficulty (the “hi-slung mandible”) where the condyles are positioned more rostral than normal. An otherwise normal jaw with this configuration recedes markedly on opening. Further studies are required to validate the model. Accurate quantification of individual factors in difficult laryngoscopy may then be feasible.