Preoxygenation before anesthetic induction and tracheal intubation is a widely accepted maneuver, designed to increase the body oxygen stores and thereby delay the onset of arterial hemoglobin desaturation during apnea. Because difficulties with ventilation and intubation are unpredictable, the need for preoxygenation is desirable in all patients.
What is the point of Preoxygenation?
Abstract. Preoxygenation before anesthetic induction and tracheal intubation is a widely accepted maneuver, designed to increase the body oxygen stores and thereby delay the onset of arterial hemoglobin desaturation during apnea.
What is the role of Preoxygenation in rapid sequence intubation RSI )?
Preoxygenation is accomplished by delivering 100% oxygen at high flow given to a spontaneously breathing patient through a nonrebreather mask for 3 minutes without "bagging" the patient.
Why do we Preoxygenate for 3 minutes?
[11] showed that preoxygenation with 3 min tidal volume breathing of 100% oxygen offers more protection against hypoxia due to prolonged apnea after induction of anesthesia than does four maximal breaths of 100% oxygen.
Why do you Hyperoxygenate before intubation?
Hypoxia is one of the most common suctioning complications. It's also preventable in most scenarios. Hyperoxygenate a patient prior to suctioning to reduce the risk of hypoxia as well as other suctioning complications.
What are the 5 Ps of RSI?
PROCESS OF RSI Preparation (drugs, equipment, people, place) Protect the cervical spine. Positioning (some do this after paralysis and induction) Preoxygenation.
What are the 6 P's of rapid sequence intubation?
The steps in performing RSI are often described by the six “P's”: preparation, preoxygenation, pretreatment, paralysis and induction, placement of the tube, and postintubation management (Fig. 5.1).
What is the purpose of premedication before surgery?
Prior to an operation, patients experience a high degree of stress and internal tension. Preoperative drug administration (premedication) is intended to reduce these stresses through anxiolytic and sedative effects.
How long should you pre oxygenate?
The traditional preoxygenation technique, which consists of 3 min of tidal volume breathing using an oxygen flow of 5 l/min; Four deep breaths within 30 s using an oxygen flow of 5 l/min; Eight deep breaths within 60 s using an oxygen flow of 10 l/min.
Why do we Preoxygenate before suctioning?
Preoxygenation is a technique of increasing inspired oxygen immediately prior to the suction procedure to increase arterial oxygen saturation. It has been suggested that preoxygenation may minimise the hypoxemia and other adverse effects associated with endotracheal suctioning (Young 1984; Cheng 1989).
How often should you suction an intubated patient?
Some patients need suction every 30 minutes due to excessive mucus production, which is quickly and easily assessed. Others may need it only once or twice per shift and may require a thorough assessment before suction is applied.
What is too much oxygen called?
Hyperoxia is a state of excess supply of O2 in tissues and organs. Oxygen toxicity occurs when the partial pressure of alveolar O2 (PAO2) exceeds that which is breathed under normal conditions. With continuous exposure to supraphysiologic concentrations of O2, a state of hyperoxia develops.
What drug is used for intubation?
[4] Common sedative agents used during rapid sequence intubation include etomidate, ketamine, and propofol. Commonly used neuromuscular blocking agents are succinylcholine and rocuronium. Certain induction agents and paralytic drugs may be more beneficial than others in certain clinical situations.
What are the 7 steps of rapid sequence intubation?
Steps of RSI (7 Ps)Preparation & Plan.Preoxygenation.Pre-treatment.Paralysis and induction.Protection and positioning.Placement with proof.Post-intubation management.
When do you do RSI?
General indications — RSII should be considered for the patient who is at increased risk of aspiration with induction of anesthesia. This includes the patient with a full stomach, gastrointestinal pathology, increased abdominal pressure, or pregnancy after 20 weeks gestation (table 1):
What is RSI anesthesia?
Rapid sequence induction (RSI) is a set of actions during induction of anaesthesia in unfasted patients or patients at risk of aspiration/regurgitation of gastric contents. The purpose of RSI is to secure the airway quickly and safely while actively reducing the risk of aspiration. RSI was first described in 1970.
What is modified RSI?
Modified rapid-sequence induction (RSI) techniques RSI is a commonly used procedure in patients with 'full stomachs' to minimize the risk of regurgitation and aspiration.
What are the risks of preoxygenation?
Potential risks of preoxygenation include delayed detection of esophageal intubation, absorption atelectasis, production of reactive oxygen species, and undesirable hemodynamic effects. Because the duration of preoxygenation is short, the hemodynamic effects and the accumulation of reactive oxygen species are insufficient to negate its benefits.
Why is preoxygenation important before intubation?
Preoxygenation before anesthetic induction and tracheal intubation is a widely accepted maneuver, designed to increase the body oxygen stores and thereby delay the onset of arterial hemoglobin desaturation during apnea. Because difficulties with ventilation and intubation are unpredictable, the need ….
What happens to the airway after emergence from anesthesia?
During emergence from anesthesia, residual effects of anesthetics and inadequate reversal of neuromuscular blockade can lead to hypoventilation, hypoxemia, and loss of airway patency. In accordance, routine preoxygenation before the tracheal extubation has also been recommended.
What is the goal of preoxygenation?
GOALS OF PREOXYGENATION. The main goal is to extend the ‘safe apnoea time’ (see below), which is more likely if these physiological objectives are met: denitrogenation of the lungs . the lungs serve as a large oxygen reservoir during apnea.
What is preoxygenation in apnoea?
Preoxygenation is the administration of oxygen to a patient prior to intubation to extend ‘the safe apnoea time’ . The primary mechanism is ‘denitrogenation’ of the lungs, however maximal preoxygenation is achieved when the alveolar, arterial, tissue, and venous compartments are all filled with oxygen.
How long does it take for a preoxygenated patient to get apnea?
In a healthy preoxygenated patient the safe apnea time is up to 8 minutes, compared to ~1 min if they were breathing room air. In some critically ill patients critical desaturation may occur immediately despite attempts at preoxygenation. Factors that decrease safe apnoea time include: critical illness.
Why does desaturation occur more rapidly in patients with airway occlusion?
In patients who develop airway occlusion, desaturation will occur more rapidly due to loss of functional residual capacity (FRC)
How much oxygen is used in apnea?
Oxygen consumption during apnea is approximately 200-250 mL/min (~3 mL/kg/min) in healthy adults.
What happens when you breathe 100% oxygen?
when a patient breathes 100% oxygen, this washes out the nitrogen, increasing the oxygen in the lungs to ~3,000 mL. achieve as close to SaO2 100% as possible. this maximises oxygen content of the blood by ensuring haemoglobin is fully saturated. oxygenate the plasma.
When intubating hypoxic critically ill patients, what is the dilemma?
A common dilemma when intubating hypoxic critically ill patients is whether to extend the period of preoxygenation if the SpO2 fails to rise adequately
Why are some clinicians reluctant to perform preoxygenation?
Some clinicians are reluctant to perform preoxygenation due to concerns that a tight fitting mask will cause discomfort to patients. Most patients tolerate preoxygenation well but a small proportion do experience significant distress from application of a tight fitting mask. A number of techniques are available which still allow fulll preoxygenation in these patients without causing distress:
What is the effect of preoxygenation with 100% oxygen?
Effective preoxygenation with 100% oxygen increases the oxygen content of gas in the patient’s FRC from 21% towards 100% which should theoretically produce a proportionate increase in the safe apnoea time. Whilst in practice achieving alveolar oxygen concentrations of 100% is not possible, increasing the end-tidal oxygen concentration to levels of 80-90% is usually readily achievable. The requirements for maximising alveolar oxygen concentration are as follows:
Why is capnography attached during preoxygenation?
Confirmation of functioning capnography: having capnography attached during preoxygenation provides an opportunity to check that the capnograph is available, ready & functioning prior to induction. This avoids confusion about whether subsequent absence of an ETCO2 trace, using any of the upper airway lifelines, is due to a measurement error or an interruption to alveolar oxygen delivery.
Why is capnography important for a face mask?
Confirmation of effective facemask ventilation: capnography is important not just for confirming correct placement of an endotracheal tube, but also for confirming whether ventilation (& thus alveolar oxygen delivery) is occurring when other lifelines are used. Even if the primary intention is placement of an endotracheal tube, a face mask is likely to be used as the primary rescue techniques if intubation is initially unsuccessful. Having capnography already attached to the face mask allows immediate assessment of whether the Green Zone has been entered as failure to obtain an ETCO2 trace when ventilating via a facemask suggests that alveolar oxygen delivery is not occurring.
Why use supplementary oxygen sources?
Use of supplementary oxygen sources can compensate for the inability of some oxygen delivery devices to provide a closed system and increase the FiO2 provided by them towards acceptable levels for preoxygenation.
What is the oxygen delivery device?
Oxygen delivery devices such as an anaesthetic circuit (circle, Mapleson, etc) or some bag-valve-mask devices, are capable of providing close to 100% oxygen due to the presence of a reservoir bag and valves as well as a mask which can create a tight seal on the face.
How many vital capacity breaths are needed to get full preo2?
Number of Breaths: as described above, 8 vital capacity breaths will usually achieve full PreO2 when gas analysis is not available.
Why is preoxygenation necessary?
Because difficulties with ventilation and intubation are unpredictable, the need for preoxygenation is desirable in all patients. During emergence from anesthesia, residual effects of anesthetics and inadequate reversal of neuromuscular blockade can lead to hypoventilation, hypoxemia, and loss of airway patency.
How to provide effective preoxygenation?
To provide effective preoxygenation, a methodical approach is necessary. The importance of preoxygenation with a tight-fitting mask should be explained to the patient beforehand. Once preoxygenation is initiated, Et o2 and F io2 values should be monitored closely. If the Et o2 value does not increase as expected, the anesthesia provider may have to hold the mask with both hands and/or replace the mask with a better-fitting one. Whenever possible, the induction should not start until the Et o2 value approximates or exceeds 90%.
How does preoxygenation affect the body?
Preoxygenation increases the body O 2 stores, the main increase occurring in the functional residual capacity. The size of the increases in O 2 volume in the various body tissues is difficult to assess with precision, but assuming that the partition coefficient for gases approximates the gas-water coefficients, the estimated increases are appreciable ( Table 1; Figure 1 ). 18, 19 The effectiveness of preoxygenation is assessed by its efficacy and efficiency. 8 Indices of efficacy include increases in the fraction of alveolar O 2 (F ao2 ), 20–22 decreases in the fraction of alveolar nitrogen (F an2 ), 23, 24 and increases in arterial O 2 tension (Pa o2 ). 25–27 Efficiency of preoxygenation is assessed from the decline of oxyhemoglobin desaturation (Sa o2) during apnea. 28–30
What is the role of preoxygenation in apnea?
The ability of preoxygenation, using a high fraction of inspired oxygen (F io2) before anesthetic induction and tracheal intubation, to delay the onset of apnea-induced arterial oxyhemoglobin desaturation has been appreciated for many years. 1–3 For patients at risk for aspiration, during rapid sequence induction/intubation where manual ventilation is undesirable, preoxygenation has become an integral component. 4–7 Preoxygenation is also important, when difficulty with ventilation or tracheal intubation is anticipated and when the patient has limited oxygen (O 2) reserves. 8, 9 In 2003, guidelines from the American Society of Anesthesiologists Task Force on the Management of the Difficult Airway included “face mask preoxygenation before initiating management of the difficult airway.” 10 Because the “cannot intubate, cannot ventilate” situation is unpredictable, the need for preoxygenation is desirable in all patients. 8, 11 In 2015, guidelines developed by Difficult Airway Society in the United Kingdom for the management of unanticipated difficult intubation included the statement that all patients should be preoxygenated before the induction of general anesthesia. 12
What is the most common side effect of preoxygenation?
Atelectasis occurs in 75% to 90% of healthy individuals undergoing general anesthesia, 87, 88 and absorption atelectasis is the most common side effect of preoxygenation. It is initiated by 2 mechanisms during anesthesia. 89–92 One mechanism is the decrease in the functional residual capacity. Both the supine position and induction ...
When should preoxygenation be performed?
Preoxygenation should also be performed whenever there is an anticipated interruption of O 2 delivery, such as during open tracheobronchial suctioning, and before and during awake fiber-optic intubation, especially in high-risk patients , such as the supermorbidly obese. The technique should be performed correctly, with monitoring of Et o2. Because the advantage of preoxygenation may be blunted in high-risk patients, various maneuvers are available to prolong its effectiveness. The clinician should be familiar with these maneuvers. Absorption atelectasis during preoxygenation can be readily minimized, and thus it should not be a deterrent to the routine use of the technique.
What are the risks of preoxygenation?
Potential risks of preoxygenation include delayed detection of esophageal intubation, absorption atelectasis, production of reactive oxygen species, and undesirable hemodynamic effects. Because the duration of preoxygenation is short, the hemodynamic effects and the accumulation of reactive oxygen species are insufficient to negate its benefits.
Why is preoxygenation important before paralysis?
THE purposes of maximally preoxygenating a patient before the induction of general anesthesia and paralysis are to provide the maximum amount of time that a patient can tolerate apnea and for the anesthesia provider to solve a cannot-ventilate, cannot-intubate situation. This issue of ANESTHESIOLOGY contains an intriguing article by Baraka et al. 1 that describes a new method of preoxygenation that may be best with regard to both efficacy and efficiency.
What is the maximum preoxygenation?
Maximal preoxygenation is achieved when the alveolar, arterial, tissue, and venous compartments are all filled with oxygen. However, patients with a decreased capacity for oxygen loading ( i.e. , decreased functional residual capacity [FRC], hemoglobin concentration, alveolar ventilation, cardiac output) or an increased oxygen extraction, or both, desaturate during apnea much faster than a healthy patient. 2,3 Consequently, in patients with oxygen transport limitations (who desaturate the fastest) and in any patient in whom difficulty in managing the airway is suspected (need to tolerate apnea the longest time), maximal preoxygenation is indicated. Moreover, because the development of a cannot-ventilate, cannot-intubate situation is largely unpredictable, the desirability/need to maximally preoxygenate is theoretically present for all patients. Along this line of thought, the American Society of Anesthesiologists Difficult Airway Algorithm, 4 which makes no mention of preoxygenation, should include a requirement for preoxygenation before the induction of general anesthesia whenever possible; obvious exclusion examples are very uncooperative adult patients and pediatric patients. Two major but preventable reasons why a patient will not be maximally preoxygenated are failure to achieve an alveolar fraction of oxygen (FA O2 )= 0.87 (i.e., failure to breathe fraction inspired oxygen tension [FI O2 ]= 1.0 through a sealed system) and insufficient time of preoxygenation.
Why is FA O2 0.87?
The major reason for failure to achieve an FI O2 = 1.0 and an FA O2 = 0.87 is a leak under the mask, allowing inspiratory entrainment of room air. Avoiding a leak between the mask and the face is the most important factor in obtaining maximal preoxygenation because it is the one factor that cannot be compensated for by an increased duration of preoxygenation, and relatively minor degrees of leak may be hard to appreciate. 5,6 Using the model of Farmery and Roe, 3 it can be shown that when preapnea FA O2 is progressively decreased from 0.87 to 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.13 (breathing room air) for a healthy 70-kg patient, apnea times to arterial saturation of oxygen (Sa O2 )= 60% are progressively decreased from 9.90 to 9.32, 8.38, 7.30, 6.37, 5.40, 4.40, 3.55 and 2.80 min, respectively. Clinical endpoints that indicate a sealed system are movement of the reservoir bag in and out with each inhalation and exhalation, respectively; presence of a normal capnogram and an end-tidal partial pressure of carbon dioxide (PET CO2) and tidal oximetry indicating appropriate inspired and end-tidal values.
Does nitrogen rebreathing cause submaximal preoxygenation?
10 However, simple calculation (and daily clinical observation of tidal oximetry) shows that the effect of nitrogen rebreathing in a completely oxygen-loaded standard anesthesia circle system is a minor factor causing submaximal preoxygenation. It is not surprising, therefore, that patients preoxygenated by the 4DB/30 sec method using an oxygen inflow rate of 35 l/min still desaturate to an Sa O2 = 90%, much faster (212 ± 92 s) than patients preoxygenated using the T method (406 ± 75 s). 11
How is preoxygenation performed?
Before preoxygenation, the reservoir bag was filled to capacity by occluding the mask opening with the palm of the hand. Patients were preoxygenated with a properly sized, tight-fitting anesthesia mask to prevent air leaks. These preoxygenation techniques were performed in a random order. Randomization was performed through a blinded pick from among five identical coins, each labeled according to one of the five preoxygenation techniques. A 5-min period of room air tidal volume breathing was allowed before each preoxygenation technique to ensure return of the arterial oxygen tension to its baseline value. An arterial blood sample was obtained before and after each preoxygenation technique and was analyzed for Pa O2 (Radiometer ABL3, Copenhagen, Denmark).
How many techniques of preoxygenation were used in the study of preoxygenation?
Each patient underwent five different techniques of preoxygenation and as such acted as his or her own control. The following preoxygenation techniques were investigated:
How many deep breaths are needed for rapid preoxygenation?
In conclusion, rapid preoxygenation can be achieved by using eight deep breaths within 60 s at an oxygen flow of 10 l/min.
How to increase oxygen flow?
Preoxygenation by the deep-breath technique may be improved by prolonging the time of deep breathing from 30 to 60 s, which allows eight deep breaths, and using an oxygen flow of 10 l/min. This approach can increase the ventilation volume to 8–9 l/min, which is about three times the FRC associated with an increase of the oxygen flow. The technique minimizes nitrogen rebreathing and ensures rapid washout of the FRC. Our study shows that the mean Pa O2 with deep breathing for 60 s at an oxygen flow of 10 l/min is significantly higher than that obtained with the four deep breaths at an oxygen flow of 5, 10, or even 20 l/min and is comparable to the value obtained with the traditional 3-min technique of tidal volume breathing.
How long does denitrogenation last?
In 1955, Hamilton and Eastwood 6 demonstrated that denitrogenation is 95% complete within 2–3 min if a subject is breathing at normal tidal volume from a circle anesthesia system with an oxygen flow of 5 l/min. These studies led to the recommendation that preoxygenation should last for 3–5 min before rapid-sequence induction of anesthesia. Preoxygenation before induction of general anesthesia increases the safe apnea time in most healthy adults to between 3 and 6 min before arterial oxygen desaturation occurs. 7
What is the best oxygen for anesthesia?
PREOXYGENATION with 100% oxygen before rapid-sequence induction of anesthesia has become a standard practice. Preoxygenation depends on spontaneous breathing of 100% oxygen, which denitrogenates the functional residual capacity (FRC) of the lungs and hence increases the FRC oxygen store and delays the onset of arterial desaturation and hypoxemia during the apneic period following induction of anesthesia and muscle relaxation. Several studies have demonstrated that most subjects are optimally oxygenated after 3 min of normal tidal volume breathing of 100% oxygen using the standard breathing systems. 1,2
What is the mean arterial oxygen tension?
In the first group of patients, the mean arterial oxygen tension following the tidal breathing technique was 392+/-72 mm Hg. This was significantly higher (P<0.05) than the values obtained following the four deep breath technique at oxygen flows of 5 l/min (256+/-73 mm Hg), 10 l/min (286+/-69 mm Hg), and 20 l/min (316+/-67 mm Hg). In contrast, the technique of eight deep breaths resulted in a mean arterial oxygen tension of 369+/-69 mm Hg, which was not significantly different from the value achieved by the traditional technique. In the second group of patients, apnea following different techniques of preoxygenation was associated with a slower hemoglobin desaturation in the eight-deep-breaths technique as compared with both the traditional and the four-deep-breaths techniques.
