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					Indian Journal of Anaesthesia 2008; 52 (1):96-97                                                 Evidence Based 2008
                                                                         Indian Journal of Anaesthesia, February Data


                                       Rapid Sequence Induction
                                                                                                               Pramila Bajaj
       The term “rapid sequence induction” (RSI) usually             Current problems and controversies
applies when tracheal intubation must be performed in a                    Between 1982 and September 2005, there has not
patient who is suspected of having a full stomach and                been a single study in which RSI was applied to patients
who is at risk for pulmonary aspiration of gastric con-              scheduled for emergency surgery. All studies dealing with
tents. The goal is to secure the airway without producing            the problem of neuromuscular blockade and intubating
any regurgitation and vomiting. The procedure involves               conditions during the course of a RSI have used elective
three objectives : 1) preventing hypoxia during the induc-           patients in whom RSI was simulated. Most of these stud-
tion- intubation sequence ; 2) minimizing the time between           ies have focused on neuromuscular profile and intubat-
induction and tracheal intubation, when the airway is un-            ing conditions comparing succinylcholine and
protected by the patient’s reflexes or by the cuffed tra-            nondepolarizing agents. After the demise of rapacuronium,
cheal tube;and 3) applying measures to decrease the                  the most interesting of the nondepolarizing agent remains
chances of pulmonary aspiration of gastric contents. The             rocuronium, introduced in the 1990s. Still, the dose re-
first of these objectives is normally met by preoxygenation.         quired to match the intubating qualities of succinylcho-
Typically , breathing 100% oxygen for 3-5 min before in-             line appears to be 1.0 mg.kg-1, at least in elective pa-
duction of anaesthesia allows the patient to sustain apnea           tients3, and that dose of rocuronium is associated with a
for a period of 5-8 min without hypoxia.1 The second ob-             long duration of action.
jective involves minimization of the induction -intubation
interval , which means that a short acting hypnotic agent                  The introduction of propofol and remifentanil into
should be administered with a neuromuscular blocking                 clinical practice had the theoretical advantage of modi-
agent with a rapid onset of action. Finally, the chance of           fying the practice of RSI because of the ability of these
                                                                     drugs to improve intubating conditions. Unfortunately,
aspiration is diminished by applying cricoid pressure, by
                                                                     most of the evidence comes from elective patients rather
refraining from positive pressure ventilation before tra-
                                                                     than emergency surgery patients. The difference might
cheal intubation is accomplished, and by waiting until neu-
                                                                     not be trivial. Early pharmacokinetics are modified by
romuscular blockade is complete to perform tracheal in-
                                                                     cardiac output, and the study of this phenomenon has
tubation .
                                                                     been termed “front-end pharmacokinetics”4. If cardiac
       All these steps have their detractors. Preoxygenation         output is decreased, as may happen in emergency pa-
has been associated with atelectasis.1, but this is a minor          tients, the early plasma concentration of drug is increased
problem compared with the added protection afforded by               because the dose is diluted in a smaller volume.
an increase in oxygen contents in the lungs. Application of
cricoid pressure has been criticized2, and positive pres-                  The question of dose was fuelled by another contro-
sure ventilation has been advocated by some. The role of             versy. A major concern with RSI is what to do if intuba-
                                                                     tion is not possible. The margin of safety is increased if
alternate airway devices, such as the ProSeal laryngeal
                                                                     the neuromuscular blocking agent has a duration of action
mask airway in patients with a full stomach is debated by
                                                                     that is shorter than the duration of apnea after proper
some. In addition, there is uncertainty regarding which
                                                                     preoxygenation. Although it was widely believed that such
patients should be considered as having a full stomach
                                                                     protection could be afforded by succinylcholine 1mg.kg-1,
and who should undergo RSI. The effectiveness of the
                                                                     recent evidence suggests that this might not be true, and
whole procedure in preventing aspiration of gastric con-
                                                                     some authors recommend a dose reduction.5 In children,
tents has not been evaluated. However, the approach is
                                                                     the use of succinylcholine has been questioned because
logical and widely applied. Emergency cases and poor
                                                                     of cases of hyperkalemia and cardiac arrest that are fre-
muscle relaxation at the time of intubation have been iden-
                                                                     quently resistant to resuscitative efforts.6 Finally, RSI has
tified as predisposing factors for pulmonary aspiration.

Senior Prof. & Head, Department of Anaesthesiology, R.N.T.Medical College, Udaipur (Raj.)
Correspondence to: Pramila Bajaj, 25, Polo Ground, Udaipur (Raj.) Email: bajajpramila@hotmail.com

                                                                96
Pramila Bajaj. Rapid sequence induction


been used outside the operating room. Not surprisingly,            unless there are contraindications to its use. The dose of
most studies in the emergency literature suggest that suc-         1mg.kg -1 without precurarization or 2mg.kg-1 with
cess at intubation is greater if neuromuscular blocking            precurarization appears to be optimal, providing adequate
agents are used.7This means that recommendations have              intubating conditions without prolonged duration. How-
to be formulated for their optimal use.                            ever, protection against hypoxia cannot be guaranteed.
                                                                   Precurarization should be limited to rocuronium
Do we need neuromuscular blocking agents                           0.03mg.kg-1 or equivalent. The optimal intubating dose
      With the introduction of propofol as a hypnotic agent        of rocuronium is 1mg.kg-1.
and the rapidly acting opioid drugs alfentanil and
remifentanil, the need for neuromuscular blocking agents           References
for intubation has been questioned. However, the quality           1.    Edmark L, Kostova- Aherdan K, Enlund M, Hedenstierna G.
of intubating conditions is less predictable and tracheal                Optimal oxygen concentration during induction of general ana-
                                                                         esthesia. Anesthesiology2003;98:28-33.
intubation becomes frequently impossible if neuromus-
cular blocking agents are omitted. In elective patients,           2.    Brimacombe JR, Berry AM, Cricoid pressure. Can J Anaesth
                                                                         1997;44:414-25.
heavy doses of alfentanil (60mcg.kg-1) or remifentanil
                                                                   3.    Andrews JI, Kumar N, van den Brom RH, et al. A large simple
(4mcg.kg-1) are required to produce conditions that ap-                  randomized trial of rocuronium versus succinycholine in rapid-
proach those produced by succinylcholine.8 These doses                   sequence induction of anaesthesia along with propofol. Acta
are associated with hypotension , and logic dictates that                Anaesthesiol Scand 1999;43:4-8.
the occurrence of such hypotensive episodes is likely to           4.    Krejcie TC, Avram MJ. What determines anesthetic induction
be greater in emergency patients. Intubation was im-                     dose? It’s the front-end kinetics, doctor ! Anesth Analg
possible in 20% of patients who received                                 1999;89:541-4.
alfentanil,30mcg.kg-1 or less, or remifentanil, 3mcg.kg-1          5.    Naguib M, Samarkandi A, Riad W, Alharby SW. Optimal dose
or less.8                                                                of succinylcholine revisited. Anesthesiology 2003;99:1045-9.
                                                                   6.    Gronert GA, Cardiac arrest after succinylcholine:mortality
       The need for neuromuscular blocking agents seems                  greater with rhabdomyolysis than receptor upregulation. An-
obvious when one considers the results obtained by emer-                 esthesiology 2001;94:523-9.
gency physicians. A review of four studies indicated that          7.    Kovacs G, Law JA, Ross J, et al. Acute airway management in
failure to intubate occurred in 0% -1.3 % in patients in                 the emergency department by non- anesthesiologists. Can J
whom RSI with muscle paralysis was applied compared                      Anaesth 2004;51:174-80.
with 8.6 % -28 % when intubation was performed under               8.    Klemola UM, Mennander S, Saarnivaara L, Tracheal intuba-
sedation only7 Three attempts were required in 2%-3%                     tion without the use of muscle relaxants: remifentanil or alfentanil
                                                                         in combination with propofol.Acta Anaesthesiol Scand
of paralyzed patients compared with a 10.7%-24% in-                      2000;44:465-9.
cidence with sedation only. Intense neuromuscular block-
                                                                   9.    Warner MA, Warner ME, Weber JG. Clinical significance of
ade can increase the chance of success at tracheal intu-                 pulmonary aspiration during the perioperative period. Anes-
bation, but it can also benefit the patient. Aspiration is               thesiology 1993;78:56-62.
less likely with profound neuromuscular blockade.9 Also,           10.   Mencke T, Echternach M, Kleinschmidt S,et al.Laryngeal mor-
the incidence of laryngeal injuries is less if intubating                bidity and quality of tracheal intubation : a randomized con-
conditions are excellent, and this situation is more fre-                trolled trial. Anesthesiology 2003; 98:1049-56.
quent 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 block-
ing agents improves intubating conditions, and probably
the risk of aspiration, over any induction technique using
only opioids and hypnotic agents . Succinylcholine re-
mains the “gold standard” and should be administered

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