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EVIDENCE BASED DATA
Year : 2008  |  Volume : 52  |  Issue : 1  |  Page : 96 Table of Contents     

Rapid Sequence Induction


Senior Prof. & Head, Department of Anaesthesiology, R.N.T.Medical College, Udaipur (Raj.), India

Date of Web Publication19-Mar-2010

Correspondence Address:
Pramila Bajaj
25, Polo Ground, Udaipur (Raj.)
India
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Bajaj P. Rapid Sequence Induction. Indian J Anaesth 2008;52:96

How to cite this URL:
Bajaj P. Rapid Sequence Induction. Indian J Anaesth [serial online] 2008 [cited 2020 Oct 20];52:96. Available from: https://www.ijaweb.org/text.asp?2008/52/1/96/60609

The term "rapid sequence induction" (RSI) usually applies when tracheal intubation must be performed in a patient who is suspected of having a full stomach and who is at risk for pulmonary aspiration of gastric con­tents. The goal is to secure the airway without producing any regurgitation and vomiting. The procedure involves three objectives : 1) preventing hypoxia during the induction- intubation sequence ; 2) minimizing the time between induction and tracheal intubation, when the airway is un­protected by the patient's reflexes or by the cuffed tra­cheal tube;and 3) applying measures to decrease the chances of pulmonary aspiration of gastric contents. The first of these objectives is normally met by preoxygenation. Typically, breathing 100% oxygen for 3-5 min before induction of anaesthesia allows the patient to sustain apnea for a period of 5-8 min without hypoxia. [1] The second ob­jective involves minimization of the induction -intubation interval, which means that a short acting hypnotic agent should be administered with a neuromuscular blocking agent with a rapid onset of action. Finally, the chance of aspiration is diminished by applying cricoid pressure, by refraining from positive pressure ventilation before tra­cheal intubation is accomplished, and by waiting until neuromuscular blockade is complete to perform tracheal in­tubation.

All these steps have their detractors. Preoxygenation has been associated with atelectasis. [1] , but this is a minor problem compared with the added protection afforded by an increase in oxygen contents in the lungs. Application of cricoid pressure has been criticized [2] , and positive pres­sure ventilation has been advocated by some. The role of alternate airway devices, such as the ProSeal laryngeal mask airway in patients with a full stomach is debated by some. In addition, there is uncertainty regarding which patients should be considered as having a full stomach and who should undergo RSI. The effectiveness of the whole procedure in preventing aspiration of gastric con­tents has not been evaluated. However, the approach is logical and widely applied. Emergency cases and poor muscle relaxation at the time of intubation have been iden­tified as predisposing factors for pulmonary aspiration.


   Current problems and controversies Top


Between 1982 and September 2005, there has not been a single study in which RSI was applied to patients scheduled for emergency surgery. All studies dealing with the problem of neuromuscular blockade and intubating conditions during the course of a RSI have used elective patients in whom RSI was simulated. Most of these stud­ies have focused on neuromuscular profile and intubat­ing conditions comparing succinylcholine and nondepolarizing agents. After the demise of rapacuronium, the most interesting of the nondepolarizing agent remains rocuronium, introduced in the 1990s. Still, the dose re­quired to match the intubating qualities of succinylcho­line appears to be 1.0 mg.kg -1 , at least in elective pa­tients [3] , and that dose of rocuronium is associated with a long duration of action.

The introduction of propofol and remifentanil into clinical practice had the theoretical advantage of modi­fying the practice of RSI because of the ability of these drugs to improve intubating conditions. Unfortunately, most of the evidence comes from elective patients rather than emergency surgery patients. The difference might not be trivial. Early pharmacokinetics are modified by cardiac output, and the study of this phenomenon has been termed "front-end pharmacokinetics" [4] . If cardiac output is decreased, as may happen in emergency pa­tients, the early plasma concentration of drug is increased because the dose is diluted in a smaller volume.

The question of dose was fuelled by another contro­versy. A major concern with RSI is what to do if intuba­tion is not possible. The margin of safety is increased if the neuromuscular blocking agent has a duration of action that is shorter than the duration of apnea after proper preoxygenation. Although it was widely believed that such protection could be afforded by succinylcholine 1mg.kg -1 , recent evidence suggests that this might not be true, and some authors recommend a dose reduction. [5] In children, the use of succinylcholine has been questioned because of cases of hyperkalemia and cardiac arrest that are fre­quently resistant to resuscitative efforts. [6] Finally, RSI has been used outside the operating room. Not surprisingly, most studies in the emergency literature suggest that suc­cess at intubation is greater if neuromuscular blocking agents are used. [7] This means that recommendations have to be formulated for their optimal use.


   Do we need neuromuscular blocking agents Top


With the introduction of propofol as a hypnotic agent and the rapidly acting opioid drugs alfentanil and remifentanil, the need for neuromuscular blocking agents for intubation has been questioned. However, the quality of intubating conditions is less predictable and tracheal intubation becomes frequently impossible if neuromus­cular blocking agents are omitted. In elective patients, heavy doses of alfentanil (60mcg.kg -1 ) or remifentanil (4mcg.kg -1 ) are required to produce conditions that ap­proach those produced by succinylcholine. [8] These doses are associated with hypotension, and logic dictates that the occurrence of such hypotensive episodes is likely to be greater in emergency patients. Intubation was im­possible in 20% of patients who received alfentanil,30mcg.kg -1 or less, or remifentanil, 3mcg.kg -1 or less. [8]

The need for neuromuscular blocking agents seems obvious when one considers the results obtained by emer­gency physicians. A review of four studies indicated that failure to intubate occurred in 0% -1.3 % in patients in whom RSI with muscle paralysis was applied compared with 8.6 % -28 % when intubation was performed under sedation only [7] Three attempts were required in 2%-3% of paralyzed patients compared with a 10.7%-24% in­cidence with sedation only. Intense neuromuscular block­ade can increase the chance of success at tracheal intu­bation, but it can also benefit the patient. Aspiration is less likely with profound neuromuscular blockade. [9] Also, the incidence of laryngeal injuries is less if intubating conditions are excellent, and this situation is more fre­quent if neuromuscular blocking agents are used. [10]

There is limited evidence on the best drug and dose of neuromuscular blocking agent indicated in RSI. Data have to be extrapolated from simulated RSI in elective patients and studies on patients requiring intubation in the emergency room. The use of neuromuscular block­ing agents improves intubating conditions, and probably the risk of aspiration, over any induction technique using only opioids and hypnotic agents. Succinylcholine re­mains the "gold standard" and should be administered unless there are contraindications to its use. The dose of 1mg.kg -1 without precurarization or 2mg.kg -1 with precurarization appears to be optimal, providing adequate intubating conditions without prolonged duration. How­ever, protection against hypoxia cannot be guaranteed. Precurarization should be limited to rocuronium 0.03mg.kg -1 or equivalent. The optimal intubating dose of rocuronium is 1mg.kg -1.

 
   References Top

1.Edmark L, Kostova- Aherdan K, Enlund M, Hedenstierna G. Optimal oxygen concentration during induction of general ana­esthesia. Anesthesiology2003;98:28-33.  Back to cited text no. 1      
2.Brimacombe JR, Berry AM, Cricoid pressure. Can J Anaesth 1997;44:414-25.  Back to cited text no. 2      
3.Andrews JI, Kumar N, van den Brom RH, et al. A large simple randomized trial of rocuronium versus succinycholine in rapid­sequence induction of anaesthesia along with propofol. Acta Anaesthesiol Scand 1999;43:4-8.  Back to cited text no. 3      
4.Krejcie TC, Avram MJ. What determines anesthetic induction dose? It's the front-end kinetics, doctor ! Anesth Analg 1999;89:541-4.  Back to cited text no. 4      
5.Naguib M, Samarkandi A, Riad W, Alharby SW. Optimal dose of succinylcholine revisited. Anesthesiology 2003;99:1045-9.  Back to cited text no. 5      
6.Gronert GA, Cardiac arrest after succinylcholine:mortality greater with rhabdomyolysis than receptor upregulation. An­esthesiology 2001;94:523-9.  Back to cited text no. 6      
7.Kovacs G, Law JA, Ross J, et al. Acute airway management in the emergency department by non- anesthesiologists. Can J Anaesth 2004;51:174-80.  Back to cited text no. 7      
8.Klemola UM, Mennander S, Saarnivaara L, Tracheal intuba­tion without the use of muscle relaxants: remifentanil or alfentanil in combination with propofol.Acta Anaesthesiol Scand 2000;44:465-9.  Back to cited text no. 8      
9.Warner MA, Warner ME, Weber JG. Clinical significance of pulmonary aspiration during the perioperative period. Anes­thesiology 1993;78:56-62.  Back to cited text no. 9      
10.Mencke T, Echternach M, Kleinschmidt S,et al.Laryngeal mor­bidity and quality of tracheal intubation : a randomized con­trolled trial. Anesthesiology 2003; 98:1049-56.  Back to cited text no. 10      




 

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