Rapid Sequence Induction Of General Anaesthesia Research Articles

A Prospective, Up-down Sequential Allocation Study Investigating the Effectiveness of Vital Capacity Breaths Using High-flow Nasal Oxygenation versus a Tight-fitting Face Mask to Preoxygenate Term Pregnant Women

(Int J Obstet Anesth. 2021;45:28–33) While neuraxial anesthesia is the preferred technique for cesarean delivery (CD), sometimes general anesthesia (GA) is warranted. Preoxygenation before rapid-sequence induction of GA in obstetric patients can prolong the time to oxygen desaturation. High-flow nasal oxygenation (HFNO) has been used in other settings, but there is a lack of data on its use in the obstetric population. A previous study examined the use of HFNO, using tidal volume breaths rather than vital capacity (VC) breaths. This current study aimed to determine the number of VC breaths needed using HFNO to achieve FETO2 ≥90% in pregnant women undergoing CD at term, and compare this to the number of VC breaths needed to achieve FETO2 ≥90% using a tight-fitting face mask for preoxygenation.

Rocuronium Versus Suxamethonium for Rapid Sequence Induction of General Anesthesia for Cesarean Section: Influence on Neonatal Outcomes

(Int J Obstet Anesth 2017;32:4–10) Rocuronium has been considered for use in rapid-sequence induction of general anesthesia for cesarean delivery as an alternative to succinylcholine. No large, randomized trials have investigated neonatal outcomes associated with maternal administration of rocuronium. A previous trial by the same authors as the present study compared rocuronium and succinylcholine for cesarean delivery and found lower Apgar scores at 1 and 5 minutes for neonates whose mothers were administered rocuronium. However, this was a secondary outcome of the earlier study and was not adequately powered for that outcome. Therefore, the investigators performed this current study with the goal to confirm these findings in a larger sample size.

Rocuronium versus suxamethonium for rapid sequence induction of general anaesthesia for caesarean section: influence on neonatal outcomes

BackgroundIn a previous study we compared rocuronium and suxamethonium for rapid-sequence induction of general anaesthesia for caesarean section and found no difference in maternal outcome. There was however, a significant difference in Apgar scores. As this was a secondary outcome, we extended the study to explore this finding on a larger sample. MethodsWe included 488 parturients of whom 240 were women from the original study. Women were randomly assigned to receive either rocuronium 1mg/kg (ROC n=245) or suxamethonium 1mg/kg (SUX n=243) after propofol 2mg/kg. Anaesthesia was maintained with up to 50% nitrous oxide and up to one minimum alveolar concentration of sevoflurane until the umbilical cord was clamped. We compared neonatal outcome using Apgar scores and umbilical cord blood gases. ResultsData were analysed for 525 newborns (ROC n=263vs. SUX n=262). There was a statistically significant difference in the proportion of Apgar scores <7 at 1min (ROC 17.5% vs. SUX 10.3%, P=0.023) but no difference at 5min (ROC 8% vs. SUX 4.2%, P=0.1) or 10min (ROC 3.0% vs. SUX 1.9%, P=0.58). There was no difference between groups in other measured outcomes. ConclusionThe use of rocuronium was associated with lower Apgar scores at 1min compared with suxamethonium. The clinical significance of this is unclear and warrants further investigation.

Airway Protection during Anesthesia for Esophagogastroduodendoscopy in Patients with Achalasia

Achalasia is a disorder characterized by aperistalsis of the esophageal body and impaired relaxation of the lower esophageal sphincter. Dysphagia and regurgitation of undigested, retained food or accumulated saliva are common presenting symptoms. Recurrent aspiration pneumonia may also occur particularly in older patients [1]. Patients with achalasia are clearly at a high risk for aspiration during general anesthesia. The rapidsequence induction technique with endotracheal intubation and cricoid pressure is, therefore, indicated [2]. This is a report of two patients with achalasia who underwent esophagogastroduodenoscopy (EGD) during general anesthesia which was induced using the rapid-sequence induction technique. The cases illustrate the limitations of the airway protection that this technique offers such high risk patients. The first patient was a 69-yr-old man, ASA physical status III, 120 kg, 175 cm, with a Mallampati class III airway. He was admitted for an EGD for evaluation of dysphagia. Recent radiographs were suggestive of achalasia. Rapid-sequence induction of general anesthesia using propofol and succinyl choline with cricoid pressure was performed with the patient in the supine, head-up position. Some difficulty in visualizing an anteriorly placed larynx was felt to be exaggerated by the cricoid pressure. Gradual release of the cricoid pressure to improve visualization of the larynx was immediately followed by regurgitation of milky fluid from the esophagus into the mouth. Immediate suctioning of the regurgitant fluid was followed by successful endotracheal intubation. The trachea was suctioned and was found to be clear of fluids prior to applying positive pressure ventilation. No evidence of aspiration was found following the procedure.

Life-saving or ineffective? An observational study of the use of cricoid pressure and maternal outcome in an African setting

Cricoid pressure is a routine part of rapid-sequence induction of general anaesthesia in obstetrics, but its efficacy in saving life is difficult to ascertain. As part of a prospective observational study of caesarean sections performed between January 1998 and June 2000 in 27 hospitals in Malawi, the anaesthetist recorded whether cricoid pressure was applied, the method of anaesthesia, the use of endotracheal intubation, the occurrence and timing of regurgitation and any other pre- or intra-operative complications. Logistic regression was used to assess the effect of cricoid pressure, type of anaesthetic and pre-operative complications on vomiting/regurgitation and death. Data were collected for 4891 general anaesthetics that involved intubation. Cricoid pressure was applied in 61%; 139 women vomited or regurgitated, but only 30 on induction of anaesthesia, in 24 of whom cricoid pressure was applied. There were 77 deaths, 11 of which were associated with regurgitation, in 10 of which regurgitation contributed to the death. Nine of the 11 mothers had cricoid pressure applied. Only one died on the table, the rest postoperatively. All those who died had preoperative complications. This study does not provide any evidence for a protective effect of cricoid pressure as used in this context, in preventing regurgitation or death. Preoperative gastric emptying may be a more effective measure to prevent aspiration of gastric contents.

Laryngeal nerve monitoring during thyroid surgery in pregnancy

A 32-week parturient required partial thyroidectomy for suspicious carcinoma. The surgeon requested laryngeal nerve monitoring to decrease the chances of laryngeal nerve injury during surgery. After rapid-sequence induction of general anesthesia and intubation, a size 3 laryngeal mask airway was inserted posterior to the endotracheal tube and the cuff inflated with 15 mL of air. A fiberoptic bronchoscope inserted through the laryngeal mask airway provided an unhindered view of vocal cords for laryngeal nerve identification and testing during surgery. This combined technique also offered the advantages of a secured airway, as well as positive pressure ventilation in the parturient during thyroid surgery.

Standard preoxygenation technique versus two rapid techniques in pregnant patients

The aim of this study was to compare three different preoxygenation techniques in pregnant women by measuring end-tidal fractional oxygen concentration (FETO2): the traditional technique of 3min tidal volume breathing (VT×3min), 8 deep breaths (8 DB) and 4 deep breaths (4 DB). Twenty pregnant volunteers without pulmonary diseases were studied during the third trimester (36–38 weeks’ gestation). Women were preoxygentated using a non-rebreathing respiratory circuit with a 3-L reservoir bag and a Capnomac Ultima calibrated before each patient to monitor FETO2 continuously. The three preoxygenation techniques were investigated in random order: VT×3min using an oxygen flow of 9Lmin−1, 4 DB within 30s using an oxygen flow of 9Lmin−1, and 8 DB within one minute using an oxygen flow of 15Lmin−1. Between each technique, 5-min room air breathing was allowed to return to baseline FETO2 assessed by the Capnomac Ultima. An FETO2⩾90% was achieved more frequently with the VT×3min and the 8 DB techniques (76%) than with the 4 DB technique (18%) (P<0.05). The average time required for obtaining an FETO2⩾90% was 107±37s. Both the VT×3min and the 8 DB techniques are therefore more effective for preoxygenation in pregnant patients than the 4 DB technique. In an acute obstetric emergency before rapid-sequence induction of general anaesthesia, 8 DB preoxygenation technique could be recommended.

Aprotinin use during deep hypothermic circulatory arrest for type A aortic dissection and cesarean section in a woman with preeclampsia

The patient was a 110-kg, 34-year-old, G2P1A0 woman at 34-weeks gestation with a past medical history significant for congenital mitral valve prolapse and preeclampsia during a previous pregnancy, which necessitated a cesarean section at that time. She was admitted to an outlying hospital at 34-weeks gestation for treatment of preeclampsia. Her initial symptoms included hypertension and peripheral edema. Initial therapy included labetalol and methyldopa. On the seventh day of hospitalization, she awoke with dyspnea and crushing substernal chest pain. Transthoracic echocardiography at this time revealed a dissection flap in the ascending aorta and aortic arch. The patient was transferred directly to the authors’ hospital for an emergent cesarean section and repair of the aortic dissection. On presentation, the patient was extremely anxious, although pain free. Her blood pressure was 150/90 mmHg, pulse 100 beats/min, and respiratory rate 18 breaths/min. Initial laboratory values revealed a hemoglobin of 10.2 g/dL, a platelet count of 187,000/mL3, sodium 138 mEq/L, potassium 4.1 mEq/L, blood urea nitrogen 4 mg/dL, and creatinine 0.5 mg/dL. Coagulation studies revealed a prothrombin time of 12.4 seconds and a partial thromboplastin time of 25 seconds. Rapid-sequence induction of general anesthesia was carried out with sodium thiopental (4 mg/kg) and succinylcholine (1.5 mg/kg). Anesthesia was maintained with a balanced technique consisting of isoflurane, fentanyl (27 g/kg), midazolam (0.18 mg/kg), and pancuronium (25 mg). Before induction, a 20gauge left radial arterial catheter was placed. A right internal jugular venous central catheter was placed after induction of general anesthesia. Before surgical incision, transesophageal echocardiography confirmed the presence of a dissection of the ascending aorta involving the aortic valve, aortic arch, and descending aorta (Figs 1 and 2). Mild aortic insufficiency was also noted. The remainder of the transesophageal echocardiography examination revealed that the mitral, pulmonic, and tricuspid valves were normal. There were no segmental wall motion abnormalities noted. Four minutes after abdominal incision (42 minutes after induction of general anesthesia), a female infant was delivered by cesarean section with Apgar scores of 5 at 1 minute and 8 at 5 minutes. The infant was taken to the neonatal intensive care unit (ICU) and was discharged home on the fourth postoperative day. After delivery, the uterine incision was closed and hemostasis obtained. Twenty units of oxytocin were administered intravenously, and uterine tone was evaluated. Hemostasis was deemed adequate, and the abdominal wound was left open and packed with sponges to facilitate examination after cardiopulmonary bypass. Sodium beef lung heparin (300 U/kg) was then administered intravenously. The kaolin activated coagulation time (ACT) was then determined to be greater than 500 seconds. An aprotinin test dose (1 mL) was administered intravenously with no adverse reaction. An intravenous loading dose of 2 million units of aprotinin was then administered, 2 million units added to the pump prime, and an intravenous infusion started at 500,000 U/h. After sternotomy, cardiopulmonary bypass was initiated using a 15F arterial inflow cannula in the femoral artery and a 2-stage venous cannula placed through the right atrial appendage. Direct examination of the aorta showed a dissection at the level of the tubular sinus extending circumferentially to the right coronary ostia. The patient was actively cooled to a nasopharyngeal temperature of 17.1°C. Deep hypothermic circulatory arrest (DHCA) was initiated to facilitate replacement of the underside of the aortic arch and ascending aorta. Reimplantation of the right coronary ostia was also performed. Total circulatory arrest time was 34 minutes and total aortic crossclamp time 64 minutes. The patient was rewarmed to a temperature of 36.5°C and subsequently weaned from cardiopulmonary bypass. No inotropes were required after cardiopulmonary bypass. The total cardiopulmonary bypass time was 162 minutes. Surgical hemostasis was obtained, and protamine (250 mg) was administered intravenously to reverse the effects of heparin. The ACT returned to normal, and the sternum was closed *B.A. Murphy, D.A. Zvara, L.H. Nelson, and N.D. Kon

Difficult Endotracheal Intubation Due to an Asymptomatic Epiglottic Cyst

Airway problems are easiest to manage when they are anticipated. Difficult intubation might, however, occur in patients with no obvious signs or symptoms suggesting airway obstruction. We describe a case of difficult intubation where the laryngeal inlet was obscured by a large epiglottic cyst that was discovered during rapid-sequence induction of general anesthesia. A 3-year-old male weighing 15㎏ was admitted for an emergency appendectomy. After preoxygenation, a rapid-sequence induction was carried out. Direct laryngoscopy (Macintosh # 1 blade) revealed a large 2-㎝ cyst arising from the lingual surface of the epiglottis. The cyst completely obstructed the view of the epiglottis and larynx, and several attempts at endotracheal intubation were unsuccessful. Fortunately, the patient was mask ventilated without difficulty and oxygen saturation was 98 - 99%. After a second 10㎎ dose of succinylcholine, intubation was attempted using the same laryngoscope blade and a styletted 4.5㎜ endotracheal tube by another anesthesiologist as cricoid pressure was maintained. By using the tube to push the cyst upward, intubation of the trachea was performed after a brief view of the arytenoid cartilages. Anesthesia and the operation then proceeded uneventfully. Following an appendectomy, an ENT surgeon removed the cyst. (Korean J Anesthesiol 2002; 42: 685-689)

Asymptomatic vallecular cyst: airway management considerations

Airway problems are easiest to manage when they are anticipated. Difficult intubation might, however, occur in patients with no obvious signs or symptoms suggesting airway difficulty. We describe a case where laryngeal inlet was obscured by a large vallecular cyst that was discovered during rapid-sequence induction of general anesthesia, causing difficulty in tracheal intubation. Once the patient was allowed to recover from general anesthesia, the trachea could be safely intubated using a fiberoptic bronchoscope.

Muscle relaxants during pregnancy and the puerperium

R EGIONAL anesthesia is usually preferred for peripartum procedures such as Cesarean section because of the consensus that it results in a decreased risk of maternal mortality relative to general anesthesia. The presence of a contraindication to regional anesthesia or extreme urgency or failure of regional technique mandate that a minority of cesarean section cases will still require general anesthesia, ranging at this time from 12% for active obstetric services (>500 deliveries/year) to 21% for smaller services (<250 deliveries/year). 1 It is well established that pregnant women have an increased risk of aspiration upon induction of general anesthesia. Additionally, most women needing Cesarean section present emergently and have not fasted. For these reasons, parturients requiting general anesthesia for Cesarean section need aspiration prophylaxis with an oral nonparticulate antacid with the possible addition of an H2-receptor antagonist and metoclopramide. A rapid-sequence induction of general anesthesia with cricoid pressure is also necessary. Succinylcholine is usually used as the muscle relaxant for intubation because of its rapid onset and brief duration. Another indication for the use of muscle relaxants in obstetric anesthesia is to assist in the management of an eclamptic seizure. If the seizure does not terminate promptly, muscle relaxation and intubation may be needed in order to protect the airway, stop the physical seizure activity, and allow adequate ventilation and oxygenation. For the reasons listed above this is also accomplished using a rapid-sequence intubation with succinylcholine. Pregnancy and the immediate postpartum period represent special physiological states that affect the pharmacokinetics and pharmacodynamics of muscle relaxants. Exposure of the soonto-be-delivered fetus to the effects of maternallyadministered muscle relaxant is another special consideration. Finally, many parturients are receiving medications that may affect neuromuscular transmission or metabolism of relaxants. SUCCINYLCHOLINE

Infusion of large particles of thiopental sodium during anesthesia induction

Study Objective: To determine the potential clinical significance of admixtures of thiopental sodium and acidic drugs, which are used, during induction of general anesthesia and can cause the formation of particles of thiopental. Design: Using an infusion setup similar to that used for a rapid-sequence induction of general anesthesia, injection of either pancuronium bromide or vecuronium bromide caused formation of particles of thiopental that were measured using a particle analyzer. The effects of delaying the injection of the muscle relaxant on particle formation and the effects of plasma on particle dissolution were studied. Measurements and Main Results: The thiopental particles had a diameter of 17 to 39 microns, with a concentration of 15,000 to 20,000 particles/ml. Particle formation was prevented when a 30-second delay preceded administration of pancuronium or vecuronium following injection of thiopental. No particle, formation was detected when succinylcholine was injected. Human plasma was far more effective than a crystalloid solution in dissolving thiopental particles. Conclusions: It is unlikely that clinically significant particles of thiopental will remain intact upon entering the bloodstream. However, mixing thiopental with pancuronium or vecuronium has the potential of disrupting intravenous access due to occlusion with particles.