Safety and efficacy of high-flow nasal oxygen for pre-oxygenation before anesthesia induction: a meta-analysis / 中华麻醉学杂志

Objective:To systematically review and evaluate the safety and efficacy of high-flow nasal oxygen (HFNO) for pre-oxygenation before anesthesia induction.Methods:Pubmed, Cochrane Library, Embase, China National Knowledge Infrastructure, Wanfang Database, China Science and Technology Journal Database and China Biomedical Literature Database were searched from inception to March 2022.All randomized controlled trials comparing HFNO and facemask ventilation for pre-oxygenation before anesthesia induction were collected.Two researchers independently assessed the quality of trials and extracted data.The primary outcome was the safe apnea time, the secondary outcomes were the lowest SpO 2 during intubation, oxygenation-related complications, patient comfort, PaO 2 and PaCO 2 before and after pre-oxygenation and after intubation.Meta-analysis was performed using RevMan 5.4 software. Results:Seventeen randomized controlled trials involving 843 patients were included in this meta-analysis.The results of meta-analysis showed that the safe apnea time was significantly longer ( MD=67.61, 95% CI 5.94-129.28, P=0.03), the lowest SpO 2 was higher during tracheal intubation ( MD=3.27, 95% CI 2.25-4.29, P<0.01), and PaO 2 was higher after pre-oxygenation ( MD=54.39, 95% CI 9.32-99.46, P=0.02) in the patients using HFNO than those using facemask ventilation.There were no statistically significant differences in the other outcomes ( P>0.05). Conclusions:HFNO for pre-oxygenation before anesthesia induction can significantly prolong the safe apnea time, increase the lowest SpO 2 during tracheal intubation, and improve the levels of PaO 2 after pre-oxygenation, and HFNO does not affect the patient′s comfort or increase the development of preoxygenation-related complications when compared with facemask ventilation.

Making Intubation and Extubation Safe in the Covid Era

@#The highly infectious COVID-19 pandemic has in a way or the other affected everyone. Health care workers particularly anaesthesists who deal with airway manipulation are at an increased risk of being infected. Invasive procedures such as intubation and extubation performed mostly by anaesthetists are classified as procedures with high risk of aerosol generating particles where respiratory droplets containing the virus can easily spread to the surroundings. Various methods of preoxygenation, intubation and extubation have been further discussed and improvised with the aim of reducing the spread of aerosolization and making intubation safe. The purpose of this review is to identify the new techniques that are safe and effective in reducing aerosolization of respiratory droplets during the process of intubation and extubation. Anaesthetists are often not familiar with these new techniques and protocols. Thus far, no scientific data has been made available to support the superiority of each technique. Further research is needed to investigate each technique in the future.

Effect of preoxygenation and apnoeic oxygenation during intubation in the critically ill patients: a network Meta-analysis / 中华危重病急救医学

Objective To systematic review the effect of preoxygenation (PreOx) and apnoeic oxygenation (ApOx) during intubation in the critically ill patients by network Meta-analysis. Methods The PubMed, Embase, the Cochrane Library, CNKI and Wanfang Data were searched by computer to collect randomized controlled trials (RCT) of PreOx and ApOx techniques in the intensive care unit (ICU) from inception to January 30th, 2019. PreOx techniques (p) included nasal cannula (NC), high flow nasal cannula (HFNC), bag valve mask (BVM), bi-level positive airway pressure (BiPAP), non-rebreather mask (NRM) and non-invasive ventilation (NIV), etc.; ApOx technique (a) referred to HFNC. Experimental group strategy was PreOx combined with ApOx, and control group strategy was PreOx alone. The outcomes were as follows: the lowest value of pulse oximetry (SpO2) during the intubation procedure, the incidence of severe desaturations (SpO2 < 0.80), and severe intubation-related complications [including SpO2 < 0.80, systolic blood pressure < 80 mmHg (1 mmHg = 0.133 kPa), vasopressor 30% dose increment, cardiac arrest and death]. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Statistic analysis was performed by RevMan 5.3 software, Stata 15.1 software and WinBUGS 1.4.3 software. Results A total of 7 RCTs involving 796 patients were included. Meta-analysis showed that, compared with the control group, the lowest SpO2 in the experimental group was significantly increased [mean difference (MD) = 1.42, 95% confidence interval (95%CI) was 0.60 to 2.25, P = 0.000 7], the incidence of severe complications was significantly decreased [odds ratio (OR) = 0.54, 95%CI was 0.32 to 0.92, P = 0.02], but the incidence of SpO2 < 0.80 did not improve significantly (OR = 0.65, 95%CI was 0.40 to 1.05, P = 0.08). The network Meta-analysis showed that, compared with non-pressure mask (NPM)p, (HFNC+NIV)p+HFNCa (OR = 51.20, 95%CI was 2.06 to 3 518.68) and NIVp (OR = 5.80, 95%CI was 1.25 to 34.70) had a significant reduction in the incidence of SpO2 < 0.80 (both P < 0.05). There were no significant differences in the incidence of severe complications during intubation among (HFNC+NIV)p+HFNCa, HFNCp+HFNCa, NIVp and NPMp. The occurrence rate of SpO2 < 0.80 and severe complications using different oxygenation techniques decreased sequentially in NPMp, HFNCp+HFNCa, NIVp and (HFNC+NIV)p+HFNCa. Conclusion (HFNC+NIV)p+HFNCa should be of a priority choice for critically ill patients during intubation.

Effect of preoxygenation and apnoeic oxygenation during intubation in the critically ill patients: a network Meta-analysis / 中华危重病急救医学

Objective To systematic review the effect of preoxygenation (PreOx) and apnoeic oxygenation (ApOx) during intubation in the critically ill patients by network Meta-analysis. Methods The PubMed, Embase, the Cochrane Library, CNKI and Wanfang Data were searched by computer to collect randomized controlled trials (RCT) of PreOx and ApOx techniques in the intensive care unit (ICU) from inception to January 30th, 2019. PreOx techniques (p) included nasal cannula (NC), high flow nasal cannula (HFNC), bag valve mask (BVM), bi-level positive airway pressure (BiPAP), non-rebreather mask (NRM) and non-invasive ventilation (NIV), etc.; ApOx technique (a) referred to HFNC. Experimental group strategy was PreOx combined with ApOx, and control group strategy was PreOx alone. The outcomes were as follows: the lowest value of pulse oximetry (SpO2) during the intubation procedure, the incidence of severe desaturations (SpO2 < 0.80), and severe intubation-related complications [including SpO2 < 0.80, systolic blood pressure < 80 mmHg (1 mmHg = 0.133 kPa), vasopressor 30% dose increment, cardiac arrest and death]. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Statistic analysis was performed by RevMan 5.3 software, Stata 15.1 software and WinBUGS 1.4.3 software. Results A total of 7 RCTs involving 796 patients were included. Meta-analysis showed that, compared with the control group, the lowest SpO2 in the experimental group was significantly increased [mean difference (MD) = 1.42, 95% confidence interval (95%CI) was 0.60 to 2.25, P = 0.000 7], the incidence of severe complications was significantly decreased [odds ratio (OR) = 0.54, 95%CI was 0.32 to 0.92, P = 0.02], but the incidence of SpO2 < 0.80 did not improve significantly (OR = 0.65, 95%CI was 0.40 to 1.05, P = 0.08). The network Meta-analysis showed that, compared with non-pressure mask (NPM)p, (HFNC+NIV)p+HFNCa (OR = 51.20, 95%CI was 2.06 to 3 518.68) and NIVp (OR = 5.80, 95%CI was 1.25 to 34.70) had a significant reduction in the incidence of SpO2 < 0.80 (both P < 0.05). There were no significant differences in the incidence of severe complications during intubation among (HFNC+NIV)p+HFNCa, HFNCp+HFNCa, NIVp and NPMp. The occurrence rate of SpO2 < 0.80 and severe complications using different oxygenation techniques decreased sequentially in NPMp, HFNCp+HFNCa, NIVp and (HFNC+NIV)p+HFNCa. Conclusion (HFNC+NIV)p+HFNCa should be of a priority choice for critically ill patients during intubation.

Effect of preoxygenation and apnoeic oxygenation during intubation in the critically ill patients: a network Meta-analysis / 中华危重病急救医学

Objective@#To systematic review the effect of preoxygenation (PreOx) and apnoeic oxygenation (ApOx) during intubation in the critically ill patients by network Meta-analysis.@*Methods@#The PubMed, Embase, the Cochrane Library, CNKI and Wanfang Data were searched by computer to collect randomized controlled trials (RCT) of PreOx and ApOx techniques in the intensive care unit (ICU) from inception to January 30th, 2019. PreOx techniques (p) included nasal cannula (NC), high flow nasal cannula (HFNC), bag valve mask (BVM), bi-level positive airway pressure (BiPAP), non-rebreather mask (NRM) and non-invasive ventilation (NIV), etc.; ApOx technique (a) referred to HFNC. Experimental group strategy was PreOx combined with ApOx, and control group strategy was PreOx alone. The outcomes were as follows: the lowest value of pulse oximetry (SpO2) during the intubation procedure, the incidence of severe desaturations (SpO2 < 0.80), and severe intubation-related complications [including SpO2 < 0.80, systolic blood pressure < 80 mmHg (1 mmHg = 0.133 kPa), vasopressor 30% dose increment, cardiac arrest and death]. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Statistic analysis was performed by RevMan 5.3 software, Stata 15.1 software and WinBUGS 1.4.3 software.@*Results@#A total of 7 RCTs involving 796 patients were included. Meta-analysis showed that, compared with the control group, the lowest SpO2 in the experimental group was significantly increased [mean difference (MD) = 1.42, 95% confidence interval (95%CI) was 0.60 to 2.25, P = 0.000 7], the incidence of severe complications was significantly decreased [odds ratio (OR) = 0.54, 95%CI was 0.32 to 0.92, P = 0.02], but the incidence of SpO2 < 0.80 did not improve significantly (OR = 0.65, 95%CI was 0.40 to 1.05, P = 0.08). The network Meta-analysis showed that, compared with non-pressure mask (NPM)p, (HFNC+NIV)p+HFNCa (OR = 51.20, 95%CI was 2.06 to 3 518.68) and NIVp (OR = 5.80, 95%CI was 1.25 to 34.70) had a significant reduction in the incidence of SpO2 < 0.80 (both P < 0.05). There were no significant differences in the incidence of severe complications during intubation among (HFNC+NIV)p+HFNCa, HFNCp+HFNCa, NIVp and NPMp. The occurrence rate of SpO2 < 0.80 and severe complications using different oxygenation techniques decreased sequentially in NPMp, HFNCp+HFNCa, NIVp and (HFNC+NIV)p+HFNCa.@*Conclusion@#(HFNC+NIV)p+HFNCa should be of a priority choice for critically ill patients during intubation.

High-flow nasal oxygenation for anesthetic management / 대한마취과학회지

High-flow nasal oxygenation (HFNO) is a promising new technique for anesthesiologists. The use of HFNO during the induction of anesthesia and during upper airway surgeries has been initiated, and its applications have been rapidly growing ever since. The advantages of this technique include its easy set-up, high tolerability, and its abilities to produce positive airway pressure and a high fraction of inspired oxygen and to influence the clearance of carbon dioxide to some extent. HFNO, via a nasal cannula, can provide oxygen both to patients who can breathe spontaneously and to those who are apneic; further, this technique does not interfere with bag-mask ventilation, attempts at laryngoscopy for tracheal intubation, and surgical procedures conducted in the airway. In this review, we describe the techniques associated with HFNO and the advantages and disadvantages of HFNO based on the current state of knowledge.

Efficacy of preoxygenation using tidal volume breathing: a comparison of Mapleson A, Bain's and Circle system / Eficácia da pré-oxigenação usando respiração em volume corrente: uma comparação dos sistemas Mapleson A, Bain e Circular

Abstract Background: Efficacy of preoxygenation depends upon inspired oxygen concentration, its flow rate, breathing system configuration and patient characteristics. We hypothesized that in actual clinical scenario, where breathing circuit is not primed with 100% oxygen, patients may need more time to achieve EtO2 ≥ 90%, and this duration may be different among various breathing systems. We thus studied the efficacy of preoxygenation using unprimed Mapleson A, Bain's and Circle system with tidal volume breathing at oxygen flow rates of 5 L.min−1 and 10 L.min−1. Methods: Patients were randomly allocated into one of the six groups, wherein they were preoxygenated using either Mapleson A, Bain's or Circle system at O2 flow rate of either 5 L.min−1 or 10 L.min−1. The primary outcome measure of our study was the time taken to achieve EtO2 ≥ 90% at 5 and 10 L.min−1 flow rates. Results: At oxygen flow rate of 5 L.min−1, time to reach EtO2 ≥ 90% was significantly longer with Bain's system (3.7 ± 0.67 min) than Mapleson A and Circle system (2.9 ± 0.6, 3.3 ± 0.97 min, respectively). However at oxygen flow rate of 10 L.min−1 this time was significantly shorter and comparable among all the three breathing systems (2.33 ± 0.38 min with Mapleson, 2.59 ± 0.50 min with Bain's and 2.60 ± 0.47 min with Circle system). Conclusions: With spontaneous normal tidal volume breathing at oxygen flow rate of 5 L.min−1, Mapleson A can optimally preoxygenate patients within 3 min while Bain's and Circle system require more time. However at O2 flow rate of 10 L.min−1 all the three breathing systems are capable of optimally preoxygenating the patients in less than 3 min.

Resumo Justificativa: A eficácia da pré-oxigenação depende da concentração inspirada de oxigênio, do fluxo de gases, da configuração do circuito respiratório e das características do paciente. Nossa hipótese foi que, no cenário clínico real, no qual o circuito respiratório não é preparado com 100% de oxigênio, os pacientes podem precisar de mais tempo para atingir EtO2 ≥ 90% e essa duração pode ser diferente entre vários circuitos de respiração. Avaliamos, portanto, a eficácia da pré-oxigenação com o uso dos circuitos não preparados Mapleson A, Bain e Circular com volume corrente de respiração com um fluxo de oxigênio de 5 L.min−1 e 10 L.min−1. Métodos: Os pacientes foram alocados aleatoriamente em um dos seis grupos, nos quais foram pré-oxigenados com o uso do circuito Mapleson A, Bain ou Circular com um fluxo de O2 de 5 L.min−1 ou 10 L.min−1. O desfecho primário de nosso estudo foi o tempo necessário para atingir EtO2 ≥ 90% com um fluxo de 5 e 10 L.min−1. Resultados: Com um fluxo de oxigênio de 5 L.min−1, o tempo para atingir EtO2 ≥ 90% foi significativamente maior com o circuito Bain (3,7 ± 0,67 min) do que com os circuitos Mapleson A e Circular (2,9 ± 0,6 e 3,3 ± 0,97 min, respectivamente). No entanto, com o fluxo de oxigênio de 10 L.min−1 foi significativamente menor e comparável entre os três circuitos respiratórios (2,33 ± 0,38 min com Mapleson; 2,59 ± 0,50 min com Bain e 2,60 ± 0,47 min com o Circular). Conclusões: Durante respiração espontânea com volume corrente normal e com um fluxo de oxigênio de 5 L.min−1, o sistema Mapleson A pode pré-oxigenar o paciente de forma ideal dentro de três minutos, enquanto os sistemas Bain e Circular requerem mais tempo. Porém, com um fluxo de O2 de 10 L.min−1, todos os três circuitos respiratórios podem pré-oxigenar o paciente de forma ideal em menos de três minutos.

Clinical Effects of High Flow Nasal Cannular Insufflation on Preoxygenation and Extension of Safe Apneic Period / 中山大学学报(医学科学版)

[Objective]To assess the effects of high flow nasal cannular insufflation(HFNCI)on preoxygenation and extension of safe apneic period during tracheal intubation.[Methods]Patients were randomly allocated into facemask(FM),facemask plus HFNCI(FM+HFNCI),HFNCI and HFNCI plus nasopharyngeal airway(HFNCI+NPA) groups. Facemask was adopted in FM and FM+HFNCI groups,while HFNCI was used in HFNCI and HFNCI+NPA groups for preoxygenation. All patients except for those in FM group received HFNCI during tracheal intubation. PaO2, SaO2,HR and MAP were recorded and analyzed.[Results]There was no significant difference in PaO2and SaO2after preoxygenation among groups(P>0.05). During apneic tracheal intubation period,PaO2decreased significantly in FM group while increased in HFNCI+NPA group. The Δ PaO2in FM group(Mean value was -5.4 kPa)was significantly bigger than those in other groups(Mean values in FM+HFNCI,HFNCI,and HFNCI+NPA groups were -0.5,-0.8 and 1.4 kPa,respectively(P < 0.001). All values at the success of tracheal intubation were much above the safe limits.[Conclusion]HFNCI provides effective preoxygenation and may extend safe apneic period in patients with patent airway.

Preoxygenation in pediatric patients

BACKGROUND: Preoxygenation with tidal volume breathing for 3 min is a standard technique using 100% oxygen for prevention of hypoxia during the induction of general anesthesia. The measurement of end tidal oxygen concentration is useful in preoxygenation monitoring. The aim of the study was to determine the effects of preoxygenation in pediatric patients during 3 min with tidal volume breathing. METHODS: Sixty patients who were scheduled for general surgery were divided into 0-6 yr old children (Group I, n = 20), 7-15 yr old children (Group II, n = 20) and adults (Group III, n = 20). Patients with an inflatable mask connected to an anesthesia machine breathed 100% oxygen spontaneously for 3 min with tidal volume in all three groups. End tidal oxygen concentration, end tidal carbon dioxide concentration and respiratory rate were measured simultaneously for 3 min. RESULTS: Group I and II showed significantly higher end tidal oxygen concentrations than Group III from 10 sec to 160 sec with 3 min tidal volume breathing (P < 0.05). The mean time required for end tidal oxygen concentration of 90% was 85.5 +/- 18.5 sec for Group I, 101.5 +/- 21.5 sec for Group II and 148.0 +/- 24.0 sec for Group III. Therefore, Group I and II showed a significantly shorter time than Group III (P < 0.05). CONCLUSIONS: Pediatric patients showed a significantly shorter time to obtain the required preoxygenation.

Comparison of the effects of preoxygenation between pregnant and non-pregnant patients

BACKGROUND: Preoxygenation is a standard anesthetic technique using 100% oxygen for the prevention of hypoxia during the induction of anesthesia. Measuring end-tidal oxygen is the most useful indicator for determining the end-point of preoxygenation. We studied the effects of preoxygenation between pregnant and non-pregnant patients during 5 min of tidal volume breathing. METHODS: Non-pregnant women who were scheduled for general surgery (Group I, n = 25) and pregnant women who were scheduled for elective cesarean section (Group II, n = 20) were explained the technique of preoxygenation, which was conducted with 100% oxygen during 5 min of tidal volume breathing. End-tidal oxygen concentration was measured at 10 sec intervals for 5 min, simultaneously. RESULTS: Group II showed significantly higher end-tidal oxygen concentration than Group I from 30 sec to 170 sec during preoxygenation (P or =90% was 110.0 +/- 31.7 sec for Group II and 152.8 +/- 34.5 sec for Group I. Therefore, Group II showed a significantly shorter time than Group I (P < 0.05). CONCLUSIONS: We concluded that the time for complete preoxygenation was shorter in pregnant patients compared to non-pregnant patients.

Utilización de la oxigenación apneica en la simpatectomía transtorácica endoscópica / Use of apneic oxygenation in endoscopic transthoracic sympathectomy

Introducción: Es aún controversial la conducta anestésica de los pacientes tratados por toracoscopia para tratamiento quirúrgico de las hiperhidrosis en los miembros superiores. Objetivos: Identificar el comportamiento de los niveles de oxigenación y del dióxido de carbono al final de la espiración, así como los posibles efectos adversos al aplicar la técnica de Oxigenación Apneica en pacientes que se les realizará simpatectomía transtorácica endoscópica T2-T3. Material y Método: Se realizó un estudio descriptivo, transversal en 16 pacientes a los que se les aplicó la oxigenación apneica empleando tubo orotraqueal convencional. En el intraoperatorio se midió el tiempo de apnea por hemitórax y se evaluó la saturación periférica arterial de oxigeno (SpO2) y el dióxido de carbono al final de la espiración (etCO2), además de la frecuencia cardiaca (FC) y la tensión arterial no invasiva (TA). Resultados: a pesar de los tiempos de apnea la oxigenación se mantuvo óptima en todos los casos, el valor medio del etCO2 no supera los 60 mmHg y no se encontraron cambios significativos de la FC y TA con respecto a los valores basales. Conclusiones: La técnica de Oxigenación Apneica es útil en este tipo de procedimiento.

Even now it is arguable the anesthetic behavior of patients underwent thoracoscopy for a surgical treatment of hyperhidrosis of upper extremities. Objectives: To identify the behavior of oxygenation and carbon dioxide (CO2 ) at the end of the exhalation, as well as the potential side effects with the application of apneic oxygenation in patients in which a T2-T3 endoscopic transthoracic sympathectomy will be carried out. Material and Methods: A cross-sectional and descriptive study was conducted in 16 patients underwent apneic oxygenation using a conventional orotracheal tube. At intraoperative period the apnea time was measured by hemithorax and the arterial peripheral oxygen saturation (Sp02) was assessed and the carbon dioxide at the end of the exhalation (etCO2), as well as the heart rate (HR) and the non-invasive blood pressure (BP). Results: Despite the apnea times the oxygenation remained optimal in all the cases, the mean value of etCO2 in under the 60 mmHg without significant changes of HR and the BP regarding the basal values. Conclusions: The apneic oxygenation technique is useful in this type of procedure.

Effects of preoxygenation with the three minutes tidal volume breathing technique in the elderly / 대한마취과학회지

BACKGROUND: Preoxygenation with tidal volume breathing for 3 min is commonly used technique. An end tidal expiratory oxygen concentration greater than 90% is considerd to be adequate for preoxygenation. The aim of this study was to check the effects of preoxygenation on elderly patients through the comparison with young patients during the 3 min tidal volume breathing technique. METHODS: Sixty patients from ASA class I or II who were scheduled for elective orthopedic general surgery were divided into an elderly (>65 yr) group and a control (25-65 yr) group. Patients were instructed in the technique of preoxygenation. Preoxygenation was accomplished with an appropriately sized face mask connected to an anesthesia machine with 100% oxygen during 3 min with patients in both groups. Expired O2, CO2 concentration and oxygen saturation were recorded simultaneously for 3 min. RESULTS: The elderly group showed significantly lower end tidal oxygen concentration than the control group from 50 sec to the end of study (180 sec) with the 3 min tidal volume breathing technique (P < 0.05). In 180 sec, the control group had over 90% (91.5%) end tidal oxygen concentration, but in the elderly group end tidal oxygen concentration could not reach 90% (86.2%). In oxygen saturation, the elderly group showed a significantly lower level until 40 sec from the start of study, and then two groups showed a similar levels of oxygen saturation until the end of study. CONCLUSIONS: End tidal oxygen concentration did not reach 90% in 180 sec in the elderly group during preoxygenation with the 3 min tidal volume breathing technique.

Effects of body mass index of patients on duration of non-hypoxic apnoea / 重庆医科大学学报

Objective:To investigate the effects ofbody mass index on duration of non-hypoxic apnoea during induction and intubation of anesthesia.Methods:80 patients undergoing surgery with general anaesthesia aged 21～63 years old with ASA Ⅰ-Ⅱgrade and without special diseases were included.they were assigned to one of four groups according to body mass index:Group 1(normal,n=20),Group 2 (overweight,n=20),Group 3(Ⅰ? obesity,n=20)and Group 4(Ⅱ?obesity,n=20).Preoxygenation was achieved with an oxygen flowof10 litre/min within 4 minutes.After rapid sequence induction of anaesthesia,the trachea was intubated and the patient was left apneic with disconnected from the anaesthesia circuit until SpO2 decreased to 90%.The time taken for desaturation to 90%from the end of induction of anaesthesia was recorded.Arterial blood samples were drawn when patients to enter the operating room and the end of induction of anaesthesia and SpO2 decreased to 90%respectively for arterial blood ga(sABG)analysis.Results:Desaturation safety period(the time to desaturation to 90%)were significantly differences between four groups with different body mass index(P

Effects of Normocapneic Preoxygenation and Air Breathing during Vital Capacity Inhalation Induction with Sevoflurane on the Ventilation / 대한마취과학회지

BACKGROUND: Sevoflurane has been used to provide an inhaled induction by using a vital capacity breath, which is fast and has few side effects. We compared the clinical effects of a vital capacity inhalation induction (VCII) with sevoflurane in patients of preoxygenation or air-breathing before anesthetic induction. METHODS: After IRB approval, patients were randomly assigned to receive preoxygenation (O2 group, 70 patients) or air breathing (Air group, 70 patients) via SIBI (Single Breath Induction) connectorTM before VCII with 8% sevoflurane in 75% N2O/O2 from primed circuit. The clinical characteristics were compared between two groups in respect to prolongation of breath holding after loss of consciousness (response to verbal command) and side effects (airway, hemodynamic, motor) during VCII. RESULTS: O2 group showed lower incidence (60.0% vs. 87.1%, P < 0.05) and shorter duration (27.1 s vs. 36.4 s, P < 0.05) in prolongation of breath holding than Air group. Otherwise, there were no significant differences in clinical effects between two groups. CONCLUSIONS: We found that preoxygenation reduces the incidence and duration of prolongation of breath holding during VCII with sevoflurane compared with air-ventilation before VCII. We suggest that the prolongation of breath holding might be related to Hering-Breuer response to maximal lung inflation during VCII.

Meta-Analysis on the Effectiveness of Interventions Applied to Preventing Endotracheal Suction-Induced Hypoxemia / 간호학회지

PURPOSE: This study was conducted to investigate the effects of the suction-induced hypoxemia interventions. METHOD: 30 suction-induced hypoxemia interventions were reviewed for the purpose of meta-analysis. RESULT: The study showed that both preoxygenation and insufflation were the most frequently examined oxygenation time periods, and hyperoxygenation combined with hyperinflation was the most commonly applied oxygenation method in order to prevent suction-induced hypoxemia. The greatest effect was obtained by providing oxygenation before and after suctioning, whereas negative effect(the contrary results from the study hypotheses) was frequently obtained by applying insufflation only. Applying hyperoxygenation combined with hyperinflation had the greatest effect over that of applying hyperoxygenation only, even though the difference between effect sizes of both methods were statistically significant. CONCLUSION: The results of meta-analysis showed that the occurrence rate of hypoxemia after suctioning was significantly reduced with the overall interventions for hypoxemia (decreasing 40% of occurrence rate), independent with time periods or methods for providing oxygenation.

Comparison of Tidal Volume Breathing and Deep Breathing Preoxygenation Techniques for a Cesarean Section / 대한마취과학회지

BACKGROUND: Preoxygenation is routine prior to rapid sequence induction of general anesthesia for a cesarean section. The aim of this study was to evaluate the preoxygenation techniques of tidal volume breathing (TVB) and deep breathing (DB) for a cesarean section. METHODS: One hundred twenty ASA I and II patients scheduled for a cesarean section under general anesthesia participated in the study. Preoxygenation was performed with 5, 7, and 10 L/min 100% oxygen. The following techniques were tested: 1) normal TVB for a 5-min period (TVB/5 min) and 2) DB for a 2-min period (4 DB/0.5 min, 8 DB/min, 12 DB/1.5 min and 16 DB/2 min). Inspired (FIO2) and end-tidal oxygen fraction (FETO2), end-tidal carbon dioxide pressure (ETCO2) and oxygen saturation (SpO2) were measured at 0.5-min intervals. RESULTS: During TVB, FETO2 increased rapidly between 0.5 and 3.5 min and plateaued by 3.5 min at 78.5%, 83.3% and 90.8% with 5, 7 and 10 L/min 100% oxygen, respectively. Four DB/0.5 min increased FETO2 to 64.7%, 67.2% and 72.3% at 5, 7, and 10 L/min 100% oxygen, respectively. As compared with four DB/0.5 min, the values of FETO2 with TVB/1.5 min and TVB/2 min were high at 7, 10 and 5 L/min 100% oxygen. CONCLUSIONS: We concluded that TVB/2 min was more effective than four DB/0.5 min in achieving preoxygenation but eight DB/min could be used in case of an emergent operation.

The Study of Preoxygenation on the Maternal and Neonatal Arterial Blood Gas Analysis in General Anesthesia for Cesarean Section / 대한마취과학회지

Preoxygenation is a standard anesthetic technique for preventing a significant hypoxemia during the induction of anesthesia. Complete denitrogenation is especially important in clinical situations of difficult intubation or in patients with decreased functional residual capacity, and in situations where oxygen saturation is critical. Methods for preoxygenation before induction of anesthesia have raised from tidal breathing of 100% O2 to taking four maximal breaths. Pregnancy produces significant physiologic changes in the respiratory system. Oxygen consumption in pregnancy is markedly increased and functional residual capacity decreases by 20-30% at term as compared to the nonpregnant stage. It is important to evaluate how long parturient women can withstand apneic hypoxemia during induction of general anesthesia. The aim of this study is to understand better how pregnancy effects preoxygenation with boths tidal breathing of 100% O2 for 3 min and four maximally deep inspiration of 100% O2 within 30 seconds technique. Twenty ASA 1 and 2 patients scheduled for elective cesarean section under general anesthesia selected for the study. After premedication with atropine sulfate 0.5 mg, we randomly divide the patients into two groups : Group 1 was preoxygenated by tidal breathing of 100% O2 for 3 min (n =10). Group 2 was preoxygenated by taking four maximally deep inspirations of 100% O2 within 30s (n = 10). We administered O2 to both groups at a flow rate of 8 Vmin via a semiclosed circle anesthesia system and a tight-fitting face mask. We performed a rapid-sequence induction of general anesthesia with thiopental 4 mg/kg iv followed by succinylcholine 1.2 mg/kg iv and intubated the trachea. We sampled maternal arterial blood immediately umbilical blood at delivery for blood gas analysis. And induction to delivery time, uterine incision to delivery time, neonatal birth weight, Apgar score were measured. The results were as follows, 1) Induction to delivery times, uterine incision to delivery times and birth weight were similarand no infant had an Apgar score of less than 8 at 1 or 5 min between two groups. 2) There were no significant differences in maternal blood gas values between the two groups. 3) Umbilical artery and venous blood gas values were similar in both groups. In conclusion, either tidal breathing of 100% O2 for 3 minutes or four maximally deep inspiration of 100% O2 within 30 seconds technique improve arterial oxygenation and similar protection against apneic hypoxemia in rapid sequence induction of general anesthesia for Cesarean section.

Preoxygenation Using End - tidal Oxygen Concentration / 대한마취과학회지

Preoxygenation is a standard anesthetic technique for preventing hypoxemia during the in- duction of anesthesia. This is achieved by alveolar denitrogenation while ventilating the lungs with 100% oxygen. Until recently there was no satisfactory nitrogen monitoring device except mass spectrometry which is not generally available. We used a convinient and readily available measuring technique to evaluate the effectpreoxygenation. In 31 healthy volunteers breathing 100% oxygen, end-tidal oxygen concentration have been measured at 15 seconds interval from the start of preoxygenation. A circle system was flushed with 100% oxygen and flow rate of 8 liter per minute. The gas sampling line of the Capnomac II (Datex, Finland) was placed in nasal cavity. At 1, 2, 3 minutes, mean end-tidal oxygen concentration was 78.7%, 89.2%, 91.9 % respectively. End-tidal nitrogen concentration was approximately 16.1 %, 5.8%, 3.2%. We conclude end-tidal oxygen concentration is a good indirect measure of denitrogenation.