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BackgroundData on postoperative outcomes of the COVID-19 patient population is limited. We described COVID-19 patients who underwent a surgery and the pandemic impact on surgical activities.MethodsWe conducted a multicenter cohort study between March 13 and June 192,020. We included all COVID-19 patients who underwent surgery in nine centres of the Province of Québec, the Canadian province most afflicted by the pandemic. We also included concomitant suspected COVID-19 (subsequently confirmed not to have COVID-19) patients and patients who had recovered from it. We collected data on baseline characteristics, postoperative complications and postoperative mortality. Our primary outcome was 30-day mortality. We also collected data on overall surgical activities during this first wave and during the same period in 2019.ResultsWe included 44 COVID-19 patients, 18 suspected patients, and 18 patients who had recovered from COVID-19 at time of surgery. Among the 44 COVID-19 patients, 31 surgeries (71%) were urgent and 16 (36%) were major. In these patients, pulmonary complications were frequent (25%) and 30-day mortality was high (15.9%). This mortality was higher in patients with symptoms (23.1%) compared to those without symptoms (5.6%), although not statistically significant (p = 0.118). Of the total 22,616 cases performed among participating centres during the study period, only 0.19% had COVID-19 at the time of surgery. Fewer procedures were performed during the study period compared to the same period in 2019 (44,486 cases).ConclusionIn this Canadian cohort study, postoperative 30-day mortality in COVID-19 patients undergoing surgery was high (15.9%). Although few surgeries were performed on COVID-19 patients, the pandemic impact on surgical activity volume was important.Trial registrationClinicalTrials.gov Identifier:NCT04458337.

We report a case of awake paralysis due to residual neuromuscular blockade (NMB) in the intensive care unit (ICU) in a patient following fast-track cardiac surgery. As a result of this case, we performed a prospective quality assurance audit to investigate the incidence of residual paralysis in the ICU in a similar population of cardiac surgery patients. A 73-yr-old woman (69 kg) underwent coronary artery bypass surgery under anesthesia induced with intravenous sufentanil 25 µg, midazolam 5 mg, ketamine 25 mg, and rocuronium 100 mg (followed by two additional 50-mg doses during surgery) and maintained with sevoflurane. Postoperatively in the ICU, the patient was initially sedated with propofol (50 mg·hr−1) but failed to awaken 90 min after its cessation. As train-of-four neurostimulation showed residual paralysis, she was re-sedated. Neostigmine 3 mg and glycopyrrolate 0.6 mg were administered, and she was extubated 30 min later. During this episode of residual paralysis, the patient was conscious and reported explicit memory of the events. She was discharged on day 7 without psychological distress related to her postoperative awake paralysis. We subsequently performed a prospective audit in 50 consecutive patients to determine the timing of NMB dosing and to quantify the incidence of residual paralysis after fast-track cardiac surgery. Of the 50 patients studied, 24 (48%) had received an NMB during the last hour of surgery and 33 (66%) had evidence of residual paralysis during the immediate postoperative period. Postoperative residual paralysis after fast-track cardiac surgery was common in our institution and likely contributed to the reported case of postoperative awake paralysis. We suggest that an NMB not be administered after intubation in fast-track patients. If given, however, it must be well communicated to the ICU team upon ICU admission. We further recommend routine assessment of neuromuscular function before sedation is weaned prior to extubation.

New regulations are in place at the federal and provincial levels in Canada regarding the way medical cannabis is to be controlled. We present them together with guidance for the safe use of medical cannabis and recent clinical trials on cannabis and pain. The new Canadian regulations on the use of medical cannabis, the provincial regulations, and the various cannabis products available from the Canadian Licensed Producers were reviewed from Health Canada, provincial licensing authorities, and the licensed producers website, respectively. Recent clinical trials on cannabis and pain were reviewed from the existing literature. Health Canada has approved a new regulation on medical marijuana/cannabis, the Marihuana for Medical Purposes Regulations: The production of medical cannabis by individuals is illegal. Health Canada, however, has licensed authorized producers across the country, limiting the production to specific licenses of certain cannabis products. There are currently 26 authorized licensed producers from seven Canadian provinces offering more than 200 strains of marijuana. We provide guidance for the safe use of medical cannabis. The recent literature indicates that currently available cannabinoids are modestly effective analgesics that provide a safe, reasonable therapeutic option for managing chronic non-cancer-related pain. The science of medical cannabis and the need for education of healthcare professionals and patients require continued effort. Although cannabinoids work to decrease pain, there is still a need to confirm these beneficial effects clinically and to exploit them with acceptable benefit-to-risk ratios.

Background and Objectives General anesthesia for breast surgery may be supplemented by using a regional anesthetic technique. We evaluated the efficacy of the first pectoral nerve block (Pecs I) in treating postoperative pain after breast cancer surgery. Methods A randomized, double-blind, dual-centered, placebo-controlled trial was performed. One hundred twenty-eight patients scheduled for unilateral breast cancer surgery were recruited. A multimodal analgesic regimen and surgeon-administered local anesthetic infiltration were used for all patients. Ultrasound-guided Pecs I was performed using bupivacaine or saline. The primary outcome was the patient pain score (numerical rating scale [NRS]) in the recovery unit 30 minutes after admission or just before the morphine administration (NRS ≥4/10). The secondary outcomes were postoperative opioid consumption (ie, in the recovery unit and after 24 hours). Results During recovery, no significant difference in NRS was observed between the bupivacaine (n = 62, 3.0 [1.0–4.0]) and placebo (n = 65, 3.0 [1.0–5.0]) groups (P = 0.55). However, the NRS was statistically significantly different, although not clinically significant, for patients undergoing major surgeries (mastectomies or tumorectomies with axillary clearance) (n = 29, 3.0 [0.0–4.0] vs 4.0 [2.0–5.0], P = 0.04). Morphine consumption during recovery did not differ (1.5 mg [0.0–6.0 mg] vs 3.0 mg [0.0–6.0 mg], P = 0.20), except in the major surgery subgroup (1.5 mg [0.0–6.0 mg] vs 6.0 mg [0.0–12.0 mg], P = 0.016). Intraoperative sufentanil and cumulative morphine consumption up to 24 hours did not differ between the 2 groups. Three patients experienced complications related to the Pecs I. Conclusions Pecs I is not better than a saline placebo in the presence of multimodal analgesia for breast cancer surgery. However, its role in extended (major) breast surgery may warrant further investigation. Clinical Trial Registration This study was registered at ClinicalTrials.gov, identifier NCT01670448.

As the use of recreational drugs increases, the likelihood of an anesthesiologist perioperatively encountering patients using or addicted to these drugs will also increase. Addicted patients may present for anesthetic care in a variety of circumstances in everyday elective surgeries or in acute or life-saving situations, such as emergency Cesarean delivery or trauma surgery. Therefore, it is important for anesthesiologists to know about the most common illicit drugs being used, their clinical presentation and side effects, and the anesthetic options that are beneficial or detrimental to these patients. The most frequently used illicit substances, apart from alcohol and tobacco, are cannabis, cocaine, heroin, prescription opioids, methamphetamine, and hallucinogens. When planning anesthetic care, it is important for anesthesiologists to understand the effects of these agents, including various drug interactions, to predict tolerance to some anesthetic agents, to recognize drug withdrawal signs and symptoms, and to be prepared to manage all these factors in the perioperative period. For optimal patient care through the perioperative period, it is critical to obtain information about patient drug use and other associated treatment in order to construct an appropriate anesthetic plan, including specific considerations during surgery, emergence, and in the postanesthesia care unit.

Cerebral oxygen desaturation during cardiac surgery has been associated with adverse perioperative outcomes. Before a large multicenter randomized controlled trial (RCT) on the impact of preventing desaturations on perioperative outcomes, the authors undertook a randomized prospective, parallel-arm, multicenter feasibility RCT to determine whether an intervention algorithm could prevent desaturations.Eight Canadian sites randomized 201 patients between April 2012 and October 2013. The primary outcome was the success rate of reversing cerebral desaturations below 10% relative to baseline in the intervention group. Anesthesiologists were blinded to the cerebral saturation values in the control group. Intensive care unit personnel were blinded to cerebral saturation values for both groups. Secondary outcomes included the area under the curve of cerebral desaturation load, enrolment rates, and a 30-day follow-up for adverse events.Cerebral desaturations occurred in 71 (70%) of the 102 intervention group patients and 56 (57%) of the 99 control group patients (P = 0.04). Reversal was successful in 69 (97%) of the intervention group patients. The mean cerebral desaturation load (SD) in the operating room was smaller for intervention group patients compared with control group patients (104 [217] %.min vs. 398 [869] %.min, mean difference, -294; 95% CI, -562 to -26; P = 0.03). This was also true in the intensive care unit (P = 0.02). There were no differences in adverse events between the groups.Study sites were successful in reversal of desaturation, patient recruitment, randomization, and follow-up in cardiac surgery, supporting the feasibility of conducting a large multicenter RCT.

This study was designed to estimate the validity of an 11-point verbal numerical rating scale (VNRS) and a 100 Unit (U) plasticized visual analogue scale (VASp) using a 100mm paper visual analogue scale (VAS) as a gold standard, to recommend the best method of reporting the intensity of acute pain in an emergency department (ED). A convenience sample of 1176 patients with acute pain were recruited in the ED of a teaching hospital. Patients18 years and able to use the different scales were included. Scales were presented randomly. Results were converted to a 0-100 U scale and validity was quantified using the Bland-Altman method and the intra-class correlation (ICC). The limits of acceptability were previously set for the limits of agreement at +/-20 U, with a constant bias. The Bland-Altman method revealed a small bias of -4 U for the VNRS and +1 U for VASp. However, the bias of the VNRS varied with the intensity of pain from -10 to +1 U. The limits of agreement between the VNRSVAS and the VASpVAS were -25; +17 U and -17; +18 U, respectively. The ICC was excellent between the VNRSVAS (0.88) and the VASpVAS (0.92). In conclusion, the VASp has a small bias, acceptable limits of agreement and an excellent intra-class correlation. It is probably a valid tool to estimate acute pain in the ED. However, the VNRS is less valid in that context because of its wide limits of agreement and variable bias (mainly in lower scores).

The aim of this article is to assess the role of cannabinoids in the treatment of acute and chronic pain in humans.Very few clinical trials looking at the analgesic effects of cannabinoids in the acute pain settings have been performed. Three recent studies have evaluated the oral administration of synthetic cannabinoids in postoperative pain. At low doses cannabinoids are not different from placebo, whereas at high doses they may be associated with adverse effects or even worsening of pain intensity. In chronic pain patients, the safety and analgesic efficacy of a number of cannabinoid compounds have recently been evaluated in several clinical trials in several chronic pain conditions. While the small size of the trials and the relatively short duration of follow-up limits broad generalization, to date there is increasing evidence that cannabinoids are safe and effective for refractory chronic pain conditions including neuropathic pain associated with multiple sclerosis, rheumatoid arthritis, and peripheral neuropathy associated with HIV/AIDS.The precise role of cannabinoids in pain treatment still needs further evaluation. Cannabinoid compounds may be more effective in the context of chronic neuropathic pain than for the management of acute pain.

Pain is an unpleasant sensation that originates from ongoing or impending tissue damage. Management of different types of pain (acute, postoperative, inflammatory, neuropathic or cancer) is the most frequent issue encountered by clinicians and pharmacological therapy is the first line of approach for the treatment of pain. This review presents and discusses recent clinical advances regarding both the improvements in delivery of analgesic drugs and improvements in the design of analgesic molecules. The new modalities of administration of analgesics used in the clinic are reviewed, including skin patches, oral and mucosal sprays, transdermal delivery systems and intranasal administration. New insights are then presented on standard drugs used to relieve pain, such as opioids (including tramadol), NSAIDs including selective cyclo-oxygenase-2 inhibitors, paracetamol (acetaminophen), local anaesthetics and adjuvant analgesics such as antidepressants, anticonvulsants (gabapentin and pregabalin), cannabinoids, ketamine and others (e.g. nefopam). Although the understanding of pain mechanisms has improved significantly recently, much more is yet to be discovered and awaited. Broadening of our knowledge is needed to improve basic and clinical research in this field in order to better alleviate pain in millions of people.

The potency of ropivacaine compared with bupivacaine in regional anesthesia remains controversial. Therefore, we compared the pharmacodynamics of equal concentrations of bupivacaine and ropivacaine in combined sciatic and femoral nerve blocks for patients undergoing knee arthroplasty. Fifty patients received 40 mL of either 0.5% bupivacaine (n = 25) or 0.5% ropivacaine (n = 25) divided between the sciatic (15 mL) and the femoral (25 mL) nerves before induction of anesthesia. Loss and recovery of sensory (% of cold sensation compared to opposite side) and motor (no contraction or normal muscle force) functions were recorded in the distribution of the femoral, saphenous, common peroneal, and tibial nerves. Pain scores and morphine consumption over 48 h were also evaluated. There were no difference between bupivacaine and ropivacaine in terms of onset of sensory and motor blockade. However, resolution of sensory and motor function was faster in the ropivacaine group but only significantly so for the sciatic nerve and between 24 to 28 h for sensory resolution and 12 to 20 h for motor function. Overall, pain scores and morphine consumption were similar. In conclusion, we showed that block resolution is different between bupivacaine and ropivacaine when administered for combined sciatic and femoral nerve blocks. A new systematic method to assess sciatic and femoral nerve blockade is proposed.

Cannabinoids have been shown to have analgesic properties in animal studies, but a potential role for these drugs in acute pain management has not been established. It was hypothesized that nabilone, an oral cannabinoid synthetic tetrahydrocannabinol analogue, decreases morphine consumption, pain scores, nausea and vomiting following major surgery.A double-blind, randomized, placebo-controlled, parallel-group pilot trial compared the effects of two different doses, 1 mg (n = 11) and 2 mg (n = 9) of nabilone, ketoprofen 50 mg (n = 11) or placebo (n = 10), given at eight-hour intervals for 24 hr. Outcomes included morphine consumption, pain scores and emesis after major surgery. Secondary outcomes included patient tolerability of the study medication.Forty-one patients (mean age 52 +/- 2 yr) undergoing gynecologic (46%), orthopedic (44%), or other (10%) surgery were recruited. Cumulative 24-hr morphine consumption was not different between the four groups, but pain scores at rest and on movement were significantly higher in the 2 mg nabilone group compared to the other groups. There were no significant differences between groups with respect to episodes of nausea and vomiting, quality of sleep, sedation, euphoria, pruritus, or the number and severity of adverse events. No serious adverse event was recorded.Contrary to the main hypothesis, high dose nabilone in the presence of morphine patient controlled analgesia is associated with an increase in pain scores in patients undergoing major surgery.

Over the past five years, there has been a considerable increase in clinical research on cannabinoid use for a range of pain syndromes. Cannabinoid products are becoming available for research and clinical use, and pharmaceutical industry interest in the potential for cannabinoids in therapeutics is also gaining momentum. The present article summarizes recent clinical trial data in the field of pain management and suggests that the potential for cannabinoid therapy for chronic pain states is encouraging. Clinicians working in pain management should be aware of the options becoming available from the cannabinoid class of medications.

Positive pressure ventilation using a laryngeal mask airway (LMA) has gained increased popularity. This study examined the influence of neuromuscular blockade on the incidence and severity of pharyngolaryngeal discomfort after positive pressure ventilation using a LMA.130 patients were included in this prospective, double-blind, randomized two-centre study. Anesthesia was induced with remifentanil and propofol and maintained using remifentanil and sevoflurane in 30% oxygen and 70% air. Patients were mechanically ventilated at 15 breaths.min(-1) with tidal volumes to maintain Petco(2) 30-40 mmHg. Patients were randomly assigned to receive no neuromuscular blocking agent (NOBLOCK group) or cisatracurium prior to LMA insertion (BLOCK group). Prior to the end of surgery, morphine 3 to 5 mg iv were injected. The ease of insertion of the LMA, cuff pressure, and inspiratory pressure were recorded. Patients were asked immediately after two hours, and 24 hr after surgery to rate sore throat, dysphonia, or dysphagia as absent, minimal, moderate or severe. Continuous and categorical data were compared using t test and Chi-squared test, respectively.68 and 62 patients were randomized to the NOBLOCK and BLOCK groups, respectively. Successful insertion on first attempt were 89% and 92% in the NOBLOCK and BLOCK groups, respectively. Mean intracuff and inspiratory pressures were 85 +/- 35 mmHg and 13 +/- 3 mmHg for the NOBLOCK group, and 96 +/- 34 mmHg and 15 +/- 2 mmHg for the BLOCK group. The immediate, two and 24 hr postoperative incidences and severity of sore throat, dysphonia, and dysphagia did not differ significantly between the two groups.Neuromuscular blockade does not influence the ease or rate of success of LMA insertion nor the incidence and severity of pharyngolaryngeal discomfort after positive pressure ventilation using a LMA.

Phonomyography (PMG) is a novel technique for measuring neuromuscular blockade (NMB). The effect of the duration of control stimulation on the onset and duration of blockade was investigated using PMG and acceleromyography (AMG).After induction of anesthesia, a microphone was placed above the middle portion of the left eyebrow, and an acceleromyographic probe was placed above the middle portion of the right eyebrow. Twenty patients were randomized to receive bilateral, single-twitch, facial nerve stimulation (0.1 Hz, 20 mA) with three minutes (n = 10) or ten minutes (n = 10) of supramaximal stimulation before mivacurium 0.2 mg.kg(-1) was administered. Onset, maximum effect, and offset of NMB were measured.Using PMG, lag time, onset time, maximum effect, and time to reach 75% of control twitch height (mean +/- SD) were 36 +/- 27 sec, 136 +/- 35 sec, 89 +/- 10%, and 12.1 +/- 4.5 min, respectively, after three minutes of control stimulation and were 40 +/- 22 sec, 122 +/- 40 sec, 93 +/- 3%, and 12.4 +/- 4.9 min, after ten minutes. Using AMG, the values were 38 +/- 23 sec, 106 +/- 28 sec, 79 +/- 6%, and 14.3 +/- 5.9 min, respectively, after three minutes and were 34 +/- 22 sec, 106 +/- 28 sec, 76 +/- 10%, and 14.9 +/- 3.7 min, after ten minutes. Compared to PMG, AMG revealed significant bias for onset time (-30 sec), maximum effect (-16%) and time to reach 75% of control twitch height (1.5 min), with wide limits of agreement of 66 sec, 22%, and 5.6 min, respectively.The duration of control stimulation did not influence the time course of blockade measured by either method. Three minutes of supramaximal stimulation is sufficient to measure pharmacodynamic parameters. AMG measures a shorter onset and longer recovery time and reduced anesthesiology the maximum effect compared to PMG.

Background. This study investigated the acoustic signal characteristics and best recording site of phonomyography at the corrugator supercilii muscle and compared phonomyography with acceleromyography. Methods. In 12 patients (group I), after induction of anaesthesia and insertion of a laryngeal mask, a microphone (frequency range 2.5 Hz to 10 kHz) was placed on six different areas on the forehead and the peak-to-peak response after single-twitch stimulation of the facial nerve was measured. The microphone was placed where the response was largest and mivacurium 0.2 mg kg ‐1 was administered. Fast Fourier transformation was applied to all signals to determine peak frequencies and the power‐frequency relationship at different stages of neuromuscular block. In an additional 15 patients (group II), the same microphone and an acceleromyographic probe were placed above the middle portion of the left and right eyebrows respectively. Onset and offset of neuromuscular block were determined after mivacurium 0.2 mg kg ‐1 . Results. In all seven women and all five men in group I, the best response was obtained just above the middle portion of the eyebrow. Peak frequency was 4.1 (SD 0.9) Hz without neuromuscular block and did not change significantly during onset and offset of neuromuscular block. Ninety per cent of the total signal power was below 40 Hz. In group II, mean onset time and maximum effect measured were 104 (20) s and 76 (10)% respectively using acceleromyography and 134 (30) s and 92 (4)% using phonomyography (P

OBJECTIVE: To provide clinicians with guidelines for the use of cannabinoid compounds in the treatment of chronic pain.METHODS: Publications indexed from 1990 to 2005 in the National Library of Medicine Index Medicus were searched through PubMed. A consensus concerning these guidelines was achieved by the authors through review and discussion.RESULTS: There are few clinical trials, case reports or case series concerning the use of cannabinoid compounds in the treatment of chronic pain. There are no randomized clinical trials examining the use of herbal cannabis in the treatment of chronic pain.CONCLUSIONS: A practical approach to the treatment of chronic pain with cannabinoid compounds is presented. Specific suggestions about the off-label dosing of nabilone (Cesamet, Valeant Canada limitée/Limited) and dronabinol (Marinol, Solvay Pharma Inc, Canada) in the treatment of chronic pain are provided.

Among several pharmacological properties, analgesia is the most common feature shared by either opioid or cannabinoid systems. Cannabinoids and opioids are distinct drug classes that have been historically used separately or in combination to treat different pain states. Indeed, it is widely known that activation of either opioid or cannabinoid systems produce antinociceptive properties in different pain models. Moreover, several biochemical, molecular and pharmacological studies support the existence of reciprocal interactions between both systems, suggesting a common underlying mechanism. Further studies have demonstrated that the endogenous opioid system could be involved in cannabinoid antinociception and recent data have also provided evidence for a role of the endogenous cannabinoid system in opioid antinociception. These interactions may lead to additive or even synergistic antinociceptive effects, emphasizing their clinical relevance in humans in order to enhance analgesic effects with lower doses and consequently fewer undesirable side effects. Thus, the present review is focused on bidirectional interactions between opioids and cannabinoids and their potent repercussions on pain modulation.

The objective of this continuing professional development module is to describe the perioperative anesthesia and pain management of patients taking opioids because of chronic pain or drug addiction.The number of patients under opioid treatment is increasing. Pain management is problematic in these patients, because regular opioid intake is associated with mechanisms of tolerance and dependence. More recently, opioid-induced hyperalgesia phenomena have been brought to light. As a rule, the usual opioid dose should be administered with the appropriate conversions, and additional requirements should be anticipated because of the surgical procedure. Local and regional anesthesia, and multimodal analgesia are indicated whenever possible. For the patient addicted to heroin or other opioids, the perioperative period is not a suitable time to initiate weaning.The physiological and pharmacological changes caused by chronic opioid intake must be understood in order to provide optimal pain management with respect to each individual and the type of procedure.

Pain is relatively refractory to most of the current analgesics, emphasizing the importance of identifying novel pharmacological agents. Thus, modulation of the cannabinoid system is a new therapeutic approach. This could be performed at several levels. For endogenous cannabinoids, it would be a modulation of their synthesis, release, cellular uptake, metabolism or interactions with cannabinoid receptors. Many recent clinical studies investigating the role of cannabinoids in various pain syndromes demonstrated overall positive results. Nevertheless, cannabis and cannabinoids as analgesic agents have not been yet unequivocally established. Targeting preferentially peripheral cannabinoid receptors to avoid unwanted psychotropic effects is a new interesting avenue requiring further investigation.

Subscribers to the Canadian Journal of Anesthesia are invited to read the following article to introduce them to a number of key articles cited in the bibliography. Reading at least the articles preceded by an asterisk (*) allows adequate preparation for the Self-Assessment Program, which can be completed by accessing the Continuing Medical Education (CME) link on the Journal site (http://www.cja-jca.org). Completion of the Self-Assessment Program will entitle subscribers to claim up to ten hours of Continuing Professional Development (CPD) under section 3 of CPD options, for a total of up to 20 Maintenance of Certification credits (note that section 3 hours are not limited to a maximum number of credits per five-year period). Obtaining CME credits for this module is not based upon attaining a specific score: the goal of participating is to define potential areas for improvement.

Autonomic influences on the heart rate have been the subject of intense research for many decades and are classically devoted to the sympathetic and parasympathetic systems. However, developments over the past few years in our knowledge of the organization of the autonomic nervous system have led to the conclusion that in addition to the classical transmitters, peptidic transmitters are clearly present and have direct or indirect actions on cardiac conduction. Neuropeptides have been found to collocate with each other or with classical transmitters, thereby increasing the variety of chemical signals that a neuron can utilize to communicate with other cells. Neuropeptides can act as neurotransmitters, neuromodulators or neurohormones. Some are produced in endocrine glands and circulate as hormones, while others are contained in cardiac myocytes, neurons, or endothelial cells in proximity to the sinoatrial node and can therefore act in a paracrine or autocrine way on the pacemaker cells to modulate heart frequency. There is evidence supporting such a role, especially for locally situated neuropeptide Y, vasoactive intestinal peptide, calcitonin gene-related peptide, substance P, angiotensin II, natriuretic peptides, endothelins and possibly many others. The role of the peptidic neurotransmitters in the conduction system should not be exaggerated. Nevertheless, neuropeptides certainly represent a new category of neurotransmitters forming a third component of the autonomic nervous system and may have complex actions with potential therapeutic implications in man.

Background and objectives: PECS I block was first described for surgery involving the pectoralis muscles. No randomized clinical trial has been conducted on surgeries that directly involve these muscles, such as subpectoral breast augmentation. We hypothesized that PECS I block would decrease pain in the postoperative period in this population. Methods: This was a randomized, double-blind, placebo-controlled trial in women undergoing subpectoral breast augmentation surgery. PECS I block was performed using 0.4 mL.kg-1 of 0.9% saline on one side and bupivacaine (0.25%) on the other side, each patient being her own control. Numeric Rating Scale (NRS) pain scores (0 − 10) were measured at rest and during movement. The primary outcome was pain score at rest 30 minutes after arrival in the PACU. To detect a clinically significant difference of 50% in pain reduction, 14 volunteers were enrolled (power of 90% and alpha < 0.05). Results: In the PACU, three patients had no difference in pain between sides, five had reduced pain on the placebo side, and six had reduced pain on the bupivacaine side. In the bupivacaine group, pain scores at rest at 5, 30 and 60 minutes and 24 hours were 4.89 (4.23 − 5.56; mean 95% CI), 3.75 (3.13 − 4.37), 3.79 (2.93 − 4.64), and 2.29 (1.56 − 3.01), respectively, whereas in the placebo group, they were 4.96 (4.32 − 5.60), 4.00 (3.50 − 4.49), 3.93 (3.12 − 4.73), and 2.29 (1.56 − 3.01), respectively. Conclusions: PECS I block in patients undergoing breast augmentation surgery does not provide better pain relief than placebo. Therefore, the indications for PECS I block in breast augmentation surgery should be reconsidered. Resumo: Justificativa e objetivos: O bloqueio PECS I foi descrito pela primeira vez para cirurgia envolvendo os músculos peitorais. Nenhum estudo clínico randomizado foi realizado em procedimentos envolvendo diretamente os músculos peitorais, como a mamoplastia de aumento submuscular. Nossa hipótese foi de que o bloqueio PECS I diminuiria a dor pós-operatória nessa população. Método: Realizamos estudo randomizado, duplo-cego, controlado por placebo em mulheres submetidas à mamoplastia de aumento submuscular. Realizamos o bloqueio PECS I com 0,4 mL.kg-1 de solução salina a 0,9% de um lado e bupivacaína (0,25%) do outro lado, sendo cada paciente seu próprio controle. Os escores da Escala de Avaliação Numérica (EAN) de dor (0 − 10) foram obtidos em repouso e durante movimento. O desfecho primário foi o escore de dor em repouso 30 minutos após a chegada à SRPA. Para detectar uma diferença clinicamente significante de 50% na redução da dor, 14 voluntárias foram incluídas (poder de 90% e alfa < 0,05). Resultados: Na SRPA, três pacientes não apresentaram diferença na dor entre os lados, cinco relataram menos dor no lado do placebo, e seis menos dor no lado da bupivacaína. No grupo bupivacaína, os escores de dor em repouso aos 5, 30 e 60 minutos e 24 horas foram 4,89 (4,23 − 5,56; IC médio 95%), 3,75 (3,13 − 4,37), 3,79 (2,93 − 4,64) e 2,29 (1,56 − 3,01), respectivamente, enquanto no grupo placebo foram 4,96 (4,32 − 5,60), 4,00 (3,50 − 4,49), 3,93 (3,12 − 4,73) e 2,29 (1,56 − 3,01), respectivamente. Conclusões: O bloqueio PECS I em pacientes submetidas à mamoplastia de aumento não oferece melhor alívio da dor do que o placebo. Portanto, as indicações para bloqueio de PECS I na cirurgia de aumento de mama devem ser reconsideradas.