Pedro Amorim

• MD
• Chief of Service (Chefe de Serviço) at Centro Hospitalar do Porto

Cardiac arrest (CA) in the operating room is rare. Among known perioperative CA causes, Takotsubo syndrome (TTS) is a well-recognized one. Perioperative TTS is more common than existing reported cases therefore anesthesiologists should be aware of its diagnosis and management. TTS is an acquired and self-limited stress cardiomyopathy usually trigge...

Background: Profound neuromuscular block (NMB) is important in surgeries where complete immobility is considered essential to improve tracheal intubation and surgical conditions. Rocuronium bromide is a commonly used NMB agent. This work describes a noninvasive approach for estimation of post-tetanic count (PTC) based on two pharmacokinetic (PK) m...

General anesthesia is a reversible drug-induced state of altered arousal characterized by loss of responsiveness due to brainstem inactivation. Precise identification of the moment in which responsiveness is lost during the induction of general anesthesia is extremely important to provide information regarding an individual’s anesthetic requirement...

Pupillary reflex dilation (PRD) is triggered by noxious stimuli and diminished by opioid administration. In the postoperative period, PRD has been shown to be correlated with pain reporting and a useful tool to guide opioid administration. In this study we assessed whether pupillary measurements taken before extubation were related with the patient...

Analgesia Nociception Index monitor provides a measurement of the nociception and anti-nociception balance based on heart-rate variability. The aim was to assess the ability of Analgesia Nociception Index (ANI) to detect standard noxious stimulation during anesthesia at different opioid concentrations in comparison to hemodynamic and Bispectral Ind...

Objective General anesthesia is a reversible drug-induced state of altered arousal characterized by loss of responsiveness (LOR) due to brainstem inactivation. Precise identification of the LOR during the induction of general anesthesia is extremely important to provide personalized information on anesthetic requirements and could help maintain an...

Background The amount of propofol needed to induce loss of responsiveness varied widely among patients, and they usually required less than the initial dose recommended by the drug package inserts. Identifying precisely the moment of loss of responsiveness will determine the amount of propofol each patient needs. Currently, methods to decide the ex...

Background: Postoperative delirium is common among older patients and preoperative identification of high-risk patients is widely recommended. The aim of this study was to assess whether preoperative cognitive performance using brief screening tools or regional cerebral oxygen saturation (SctO2) was associated with the development of postoperative...

Using a targeted controlled infusion of remifentanil during total intravenous anesthesia, we investigated the effect-site concentrations of remifentanil that correlate with different values of the Pupillary Pain Index and which concentrations were necessary for achieving a Pupillary Pain Index ≤ 4 and its usefulness in titrating opioids. The Pupill...

Patterns of Hysteresis Between Induction and Emergence of Neuroanesthesia Are Present in Spinal and Intracranial Surgeries

In general anesthesia, Neuromuscular Blockade (NMB) agents are administered to ensure intubation quality and complete immobilization. Monitoring NMB, based on the evoked response evaluation after a peripheral nerve stimulation, is essential to provide insight on medication dosing and suitable approaches for NMB reversal. Professionals often rely on...

The aim of this study was to investigate the relation between the blink reflex evoked by an electrical stimulus and the depth of anesthesia induced with intravenous anesthetic drug propofol. The blink reflex was stimulated before the propofol infusion started (baseline) and after, every 6 s. The electromyographic responses and the level of sedation...

Background Rocuronium is a muscle relaxant with increased use interest due to the binding relation with the reversal agent sugammadex. The purpose of this review entails the investigation of its use for the maintenance of deep neuromuscular block (NMB) via continuous infusion. Methods Based on PRISMA systematic search guidelines, databases include...

Objectives: Rocuronium is a muscle relaxant with increased use, because of the binding relation with the reversal agent sugammadex. Its continuous infusion benefits the maintenance of deeper levels of neuromuscular blockade (NMB) ensuring an improved and stable solution for daily surgical anesthesia. This is systematic review on current approaches...

Background: Anesthesia induction and maintenance with propofol can be guided by target-controlled infusion (TCI) systems using pharmacokinetic (Pk) models. Physiological variables, such as changes in cardiac output (CO), can influence propofol pharmacokinetics. Knee-chest (KC) surgical positioning can result in CO changes. Objectives: This study...

Background and objectives: According to the manufacturer, the Bispectral Index (BIS) has a processing time delay of 5-10s. Studies addressing this have suggested longer delays. We evaluated the time delay in the Bispectral Index response. Methods: Based on clinical data from 45 patients, using the difference between the predicted and the real BI...

Background and objectives According to the manufacturer, the Bispectral Index (BIS) has a processing time delay of 5-10 s. Studies addressing this have suggested longer delays. We evaluated the time delay in the Bispectral Index response. Methods Based on clinical data from 45 patients, using the difference between the predicted and the real BIS,...

This review aims to give an overview of the current state of monitoring depth of anaesthesia and detecting the moment of loss of consciousness, from the first clinical signs involved in anaesthesia to the latest technologies used in this area. Such techniques are extremely important for the development of automatic systems for anaesthesia control,...

Background: Induction of anesthesia and the knee-chest position are associated with hemodynamic changes that may impact patient outcomes. The aim of this study was to assess whether planned reductions in target-controlled infusion propofol concentrations attenuate the hemodynamic changes associated with anesthesia induction and knee-chest position...

A 20-year-old man submitted to surgical insertion of a lumboperitoneal drain as a treatment for intracranial hypertension, secondary to venous sinus thrombosis, developed severe headache accompanied by nausea, vomiting, and diplopia 24 hours postoperative. Cerebral spinal fluid low-pressure headache was diagnosed. A transnasal sphenopalatine gangli...

Introduction: The Postoperative Quality Recovery Scale is a brief instrument of six domains designed to assess quality of recovery from early to long term after surgery. This study aims to validate the Portuguese version of the Postoperative Quality Recovery Scale. Material and Methods: In this observational study 101 adult patients undergoing elec...

Background: Recovery of consciousness is usually seen as a passive process, with emergence from anesthesia depicted as the inverse process of induction resulting from the elimination of anesthetic drugs from their central nervous system sites of action. However, that need not be the case. Recently it has been argued that we might encounter hystere...

This review aims to give an overview of the current state of monitoring depth of anaesthesia and detecting the moment of loss of consciousness, from the first clinical signs involved in anaesthesia to the latest technologies used in this area. Such techniques are extremely important for the development of automatic systems for anaesthesia control,...

Background Patients with intellectual disability (ID) often require general anesthesia during oral procedures. Anesthetic depth monitoring in these patients can be difficult due to their already altered mental state prior to anesthesia. In this study, the utility of electroencephalographic indexes to reflect anesthetic depth was evaluated in pediat...

Background and objectives: Postoperative delirium and postoperative cognitive dysfunction are some of the most common complications in older surgical patients and are associated with adverse outcomes. The aim of this study was to evaluate portuguese anesthesiologists' perspectives and knowledge about adverse postoperative cognitive disorders, and...

The Bispectral Index (BISTM) is validated to assess depth of anesthesia in patients with a normal brain. A bilateral BIS sensor may be used to assess cerebral ischemia by allowing the comparison of the electroencephalogram (EEG) between the two cerebral hemispheres. Bilateral BIS displays the spectrogram of the EEG and an asymmetry index. We report...

Background and objectives Postoperative delirium and postoperative cognitive dysfunction are some of the most common complications in older surgical patients and are associated with adverse outcomes. The aim of this study was to evaluate Portuguese anesthesiologists’ perspectives and knowledge about adverse postoperative cognitive disorders, and ro...

doi:10.1097/ANA.0000000000000452

Ketamine is an important component of multimodal treatment and a commonly used anesthetic drug. However, its analgesic effects have not been fully assessed intraoperatively because of difficulties in measuring this effect. In this case report, a woman underwent general anesthesia with ketamine and its pupillary reflexes were measured to detect auto...

The assessment of the adequacy of general anesthesia for surgery, namely the nociception/anti-nociception balance, has received wide attention from the scientific community. Monitoring systems based on the frontal EEG/EMG, or autonomic state reactions (e.g. heart rate and blood pressure) have been developed aiming to objectively assess this balance...

Introduction: Narcoleptic patients may be at increased risk of prolonged emergence, postoperative hypersomnia, apneic episodes, and sleep paralysis after general anesthesia. Modafinil is the first-line treatment, however, the implication it has on general anesthesia is not clear. This report present 2 cases of narcoleptic patients medicated with m...

Background • We have previously reported a high interpatient variability in propofol requirements for induction of anesthesia more than 250%. • We hypothesized that basal metabolism could also have a high interpatient variability and that it could be related to propofol requirement to induce LOC (loss of consciousness). • We prospectively measure...

To model the effect of anesthetic drugs on the Bispectral Index (BIS) of the EEG is of great importance for a reliable predictive response model during surgery. In this study, the impact of using two different drug infusion profiles in a pharmacodynamics interaction model was studied and the methods were compared with respect to their performance....

Anesthesia induction is a high risk step in every surgical procedure. However, monitoring and control of anesthesia depth is not fully developed, due to the lack of constant correlation between vital signs and drug infusion. This work proposes a LabVIEW user-friendly application tool to control syringe pumps using serial communication protocol, to...

Venous air embolism (VAE) is the air bubble accumulation in the right side of the heart, or in the pulmonary region. Pre-cordial Doppler allows a real-time monitoring of heart sound and is used to detect VAE episodes through changes in cardiac sound. Sometimes these changes are not detected by the operator, which reveals the importance of finding o...

Somatosensory evoked potentials (SEPs) have been linked to noxious activation and stimulus intensity. In this exploratory study we investigated the impact of anaesthetic drugs on SEPs and pain ratings, to assess their applicability as an objective measure of the nociception/anti-nociception balance. Following institutional approval and written info...

Background Quality of postoperative recovery is an important outcome after surgery. An observational cohort study was designed to assess the quality of postoperative recovery using the Portuguese version of the Postoperative Quality Recovery Scale (PQRS) in patients treated with neostigmine vs. sugammadex as neuromuscular blocking reversal agents....

When anesthetized patients are hypovolemic, colloid solutions, such as hydroxyethyl starch (HES), are often used to restore the volemia and prevent tissue hypoperfusion. Previous studies revealed that the anesthetic propofol and HES form a complex with different physical-bio-chemical behavior than the single drugs (Silva et al., 2013). We hypothesi...

Venous air embolism (VAE) is the air bubble accumulation in the right side of the heart. Changes in Doppler heart sound (DHS) are characteristic of VAE, and the anesthesiologist has to pay attention to this event continuously, which may not always be possible. This work aims to study different features of the heart sound through a precordial Dopple...

Continuous erector spinae plane block for analgesia in pediatric thoracic surgery: A case report. Erector spinae plane block has been recently described and it appears as a very promising regional analgesia technique. We report the first continuous erector spinae plane block performed in a pediatric patient for thoracic surgery. A 15-month-old boy...

Bleeding changes the haemodynamics, compromising organ perfusion. In this study, the effects of bleeding followed by replacement with hydroxyethyl starch 130/0.4 (HES) or lactated Ringer's (LR) on cerebral oxygenation and electroencephalogram-derived parameters were investigated. Twelve young pigs under propofol-remifentanil anaesthesia were bled 3...

Background: Hydroxyethyl starch (HES) is one of the most used colloids for intravascular volume replacement during anesthesia. Aim: To investigate the existence of a chemical interaction between HES and the anesthetic propofol by in vitro propofol dosing, computational docking, and examination of a complex between propofol and HES by infrared (I...

To study the effects of a high remifentanil bolus dose on pig's electroencephalographic indices and on brain regional and global oxygenation. Prospective experimental study. Twelve healthy Large-White male pigs, age 3 months and weight 26.2 ± 3.6 kg. Anaesthesia was induced with intravenous propofol 4 mg kg(-1) , then maintained with constant rate...

The effect of drugs' interaction on the brain signal Bispectral Index (BIS) of the EEG, is of great importance for an anesthesia control drug infusion system. In this study, the objective was to investigate if an autoregressive with exogenous inputs model (ARX) could be a suitable approach to predicting BIS according to the anesthetic drugs concent...

Cardiovascular variability and homeostasis control in response to precise noxious stimuli and different analgesic doses were analyzed. Cardiovascular variability was altered in response to noxious stimulation, and amplitude responses varied in a dose-dependent manner with the analgesic. Responses were more pronounced to laringoscopy/intubation, whe...

Acupuncture is a low-risk intervention that is increasingly used. Some studies examined the potential effects of acupuncture on anxiety and the bispectral index of the EEG (BIS), used as an objective and indirect measure of anxiolysis. Those studies used the same acupuncture point and achieved conflicting results.Objectives To objectively assess th...

A laryngoscope is a medical device commonly used in most hospitals worldwide and used to conduct an oral or endotracheal intubation which leads to changes in the patient parameters (heart rate, blood pressure, etc.) due to the force applied on the tongue and other soft-tissues. However, these parameters are being monitored continuously, and provide...

A laryngoscope is a medical device used to facilitate endotracheal intubation during general anesthesia or mechanical ventilation. Usually, a laryngoscopy can be performed in less than a minute, but requires very precise movements and force control abilities; otherwise, it may result in serious damages to the patient incisors, larynx, spinal column...

Our aim was to quantify the interaction between propofol and remifentanil on BIS for sedation, and analyse the effect on other clinical variables. Methods: Healthy unpremedicated volunteers participated in the study. BIS, systolic arterial pressure (SAP), heart rate (HR), ETCO2 and SpO2 were monitored. TCI was used for propofol (Schnider PK 1) and...

Target Controlled Infusion (TCI) systems are based in drug Pharmacokinetic (Pk) and Pharmacodynamic (Pd) models implemented in an algorithm to drive an infusion device. Several studies had compare manual titration of anesthesia and TCI system use; some studies evaluate the performance of the control algorithms for TCI systems, and a considerable nu...

A laryngoscope is a surgical instrument used to facilitate endotracheal intubation task during general anaesthesia or mechanical ventilation. This task usually takes less than a minute, but requires very precise movements and force control ability; otherwise it may result in serious damages to the patient incisors, larynx, spinal column, changes in...

Anesthetic drugs with a rapid onset of action and a short half-live, such as the hypnotic propofol and the analgesic opioid remifentanil, allowed easy control of the anesthetic depth and noxious stimuli associated to surgical interventions, and revealed most of the potential of target controlled infusion for general anesthesia Mathematic models wer...

Background: High doses of remifentanil are often required to prevent autonomic responses to noxious stimuli, but causes changes in cerebral hemodynamics. Patients with intracranial pathologies may be more sensitive to the remifentanil induced hemodynamic effects. This study addresses the effect of high remifentanil doses in patients with brain tumo...

Patients with hypertension may be more prone to develop hypotension as a consequence of opioid administration under general anesthesia. The hemodynamic and bispectral index responses to a remifentanil bolus in neurosurgical hypertensive patients under target-controlled infusion with propofol and remifentanil are addressed. Ten healthy patients and...