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Removal of the laryngeal mask airway in children: Deep anesthesia versus awake
ELSEVIER
Original Contributions Removal of the Laryngeal Mask Airway in Children: Deep Anesthesia versus Awake William M. Splinter, MD, FRCPC,* Craig W. Reid, MD, FRCPC* Department Department
of Anaesthesia, Children’s Hospital of Eastern Ontario, Ottawa, and of Anaesthesia, University of Ottawa, Ottawa, Ontario, Canada.
Study Objective: To compare the incidence of adverse airway euents identified with removal of the laryngeal mask airway (LMA) f rom an awake child or from a child before his or her airway reflexes had returned. Design: Prospective, randomized study. Setting: University-affiliated children’s hospital. Patients: 333 ASA physical status I and II patients ages 1.5 to 15 years undergoing elective surgery. Interventions: At the time of removal of the LMA at the end of surgery, patients were anesthetized or had intact airway reflexes. Measurements and Main Results: Any ainuay problems occurring within 15 minutes of LMA removal were recorded. These problems included airway obstruction (laryngeal spasm and biting of the LMA), peripheral hemoglobin oxygen saturation less than 90%, strider requiring manipulation of the airway, vomiting, retching, and excessive salivation. Airway problems occurred after Lh44 removal among 23 children who had their LMA removed prior to return of airway reflexes, and among 13 subjects who had their IM removed afer the return of airway reflexes. Conclusion: Removal of the LMA during anesthesia and afte-r return of airway reflexes results in a similar inn’dence of airway problems in children. 0 1997 by Elsevier Science Inc. *Assistant Professor
Keywords:
Address correspondence to Dr. Splinter at the Department of Anaesthesia, Children’s Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, Ontario, Canada KIH 8Ll.
Introduction
Supported by a grant from the Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada. Received for publication October 11, 1995; revised manuscript accepted for publication April 16, 1996. *Brain AlJ: Instruction
The Intavent
Manual.
Intavent Ltd., 1991.
Lmyngeal
Mask Airway
Henley-on-Thames,
UK:
Anesthesia,
pediatric;
equipment:
Laryngeal
Mask Airway.
For many operative procedures, standard intraoperative airway management includes the insertion of a laryngeal mask airway (LMA). The optimal time to remove this airway is not known. Brain,* who invented the device, and the manufacturer recommend that the LMA be removed “awake”; that is, after the patient’s airway reflexes have returned. In contrast, Gataure et al.,’ concluded that it may be safer to remove the LMA while adult patients are deeply anesthetized. The reported incidence of problems with removal of the LMA after the patient has awakened is 10% to 53%, while the incidence after removal from the anesthetized, “deep” patient has varied from 2.6% to 27%.ie5 McGinn et al4 and
Journal of Clinical Anesthesia 94-7, 1997 0 1997 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0952-8180/97/$17.00 PI1 SO952-8180(96)00217-6
LMA
Laffon et al.’ compared removal of the LMA from the awake patient versus the deeply anesthetized patient, and found that patients who had their LMA removed while they were awake had more problems than patients who had the LMA extracted while anesthetized. This result disagrees with Brain’s recommendations. Unfortunately, both of these studies had flaws, which included a lack of randomization by McGinn et aL4 and, in Laffon et al.‘s study,5 the LMA removal was performed by inexperienced users. The purpose of our prospective, randomized study of children was to compare the incidence of adverse events associated with removal of the LMA either from the deeply anesthetized or awake patient.
Materials
and Methods
Following Research Ethics Committee of the Children’s Hospital of Eastern Ontario approval and parental consent, 333 healthy ASA physical status I and II patients ages 1.5 to 15 years were enrolled into this randomized, singleblind study. Patients undergoing airway surgery, or suffering from any disease that may affect airway reflexes, including recent upper respiratory tract infection or symptomatic asthma, were excluded. The patients were randomly assigned to one of the two study groups via a computer-generated random numbers table. The two groups were similar, except for the depth of anesthesia at the time of removal of the LMA, which was either before the return of airway reflexes (deep anesthesia) or after the patient had awakened and had intact airway reflexes. Following the application of standard anesthesia monitoring, the induction of anesthesia was by inhalation of halothane and nitrous oxide (N,O) or intravenously (IV) with propofol. A standard, nonreinforced LMA was inserted after induction of anesthesia. The appropriately sized, lubricated (2% lidocaine jelly) LMA was inserted in accordance with published guidelines4 A bite block was inserted with each LMA. Maintenance of anesthesia was primarily with N,O and halothane. Older patients received isoflurane instead of halothane. Patients received IV opioids and were administered regional anesthetics when clinically indicated. In the deep anesthesia group, a surgical plane of anesthesia was maintained until the or-opharynx had been gently suctioned to prevent inadvertent aspiration of pharyngeal contents, at which time the LMA was removed and the halothane was discontinued. Patients in the awake group were transferred to the recovery room and their LMA was removed by the nursing staff once they were exhibiting purposeful movements, including swallowing, as an indication of the return of airway protective reflexes. All persons who removed the LMA were experienced anesthesiologists or recovery room nursing staff. Prior to removal of the LMA, we made no special inter-
and Reid
Results Although we enroled 333 patients into this study, 25 patients were subsequently removed from the study because a Lh4A was not used (n = 17) or surgery was cancelled (n = 8). The primary reason for not using the LMA was lack of availability of the appropriately-sized LMA. The groups were similar with respect to age, weight, induction technique, length of anesthesia, and peripheral hemoglobin SpO, immediately before LMA removal (Table 1). The LMA was removed 1 f 3 minutes and 12 + 6 minutes (means f SD) after surgery was completed for the deep and awake groups, respectively. The laryngeal cuff was not deflated before LMA removal for 47 of the patients in the deep group and 10 patients in the awake group. An adverse event associated with LMA removal was noted in 36 patients. Problems occurred in 23 patients who had their LMA removed before the return of airway reflexes, while 13 patients who had removal of their LMA awake in the recovery room had a problem. The incidence of problems was not altered by the decision to have the LMA cuff inflated or not at the time of removal. The lowest SpO, level was similar between the groups studied (Table 2). Nine patients developed an SpO, of less than 90%, 3 in the “deep” removal group and 6 in the “awake” removal group (Figure 1). All four cases of laryngospasm
Table 1. Demographic Data Group
(~4
Weight (kg) Anesthesia time (min) Instruction
+linter
ventions, such as the administration of IV lidocaine or opioids, to blunt airway responses. Patients were observed by an anesthesiologist or recovery room nurse and monitored with a pulse oximeter after LMA removal. Any problems relating to the airway were recorded for 15 minutes after LMA removal. Specific problems noted by the observers included any airway obstruction (laryngeal spasm and biting of the airway), peripheral hemoglobin oxygen saturation (SpO,) less than 90%, stridor requiring manipulation of the airway, vomiting, retching, and/or excessive salivation. All problems were treated in the routine fashion. The remainder of the postoperative care was not altered by this study. Demographic data were assessed with Student’s t-test and Chi-square analysis, where appropriate. The incidence of problems was compared with Fisher’s exact test or Chisquare analysis, where relevant. Sample size was based on the following assumptions: an acceptable difference between the groups of 10% (5% us. 15%), a power of SO%, and a tolerated chance of a Type I error of 5%.
&e
*Brain AIJ: The Intavent Lmyngzal Mask Airnay Henley-on-Thames, UK: Intavent Ltd., 1991.
in childrat
Deep
Awake
6.1154 f 3.8 24k14 46+23
6.9156 i 4.0 28+ 17 47*23
Manual.
Note: Data are means f SD.
J. Clin. Anesth., vol. 9, February
1997
5
Original Contributions
Table 2. Recovery and Problems with Laryngeal Mask Airway Removal Group Problems Lowest hemoglobin spa, (%I Incidence of hemoglobin spo, < 90% Stridor Laryngospasm Breath holding Retching, vomiting Excessive salivation
Deep
Awake
23/155
13/155
98 + 3
98 k 4
>0.5
3/155 16 3 3 2 1
6/155 6 1 4 2 0
>0.5 0.14* 20.5 >0.5 >0.5 >0.5
p-V&U?
0.07
*Chi-square analysis, pvalue listed is after due consideration of multiple testing. SpO, = oxygen saturation as measured by pulse oximetry.
responded to continuous positive simple airway support measures.
airway
pressure
and
Discussion Removal of the LMA before or after return of airway reflexes resulted in a similar incidence of postoperative airway problems. The overall incidence of problems was 12%, which is similar to previous investigations,‘4 except Laffon et ~1.~Mason and Bingham’ observed a 13% incidence of problems (coughing, biting, laryngospasm, retching, vomiting) among children during awake removal. These events were minor in nature and promptly resolved. Reddy and Win’ noted a 20% incidence of problems (clenching of teeth, excessive salivation, and vomiting) associated with LMA removal from 50 patients. McGinn et aL4 investigated several aspects of the usage of a LMA, which included timing the removal of the airway. They studied 211 children in a nonrandomized fashion. The incidence of adverse events among the 76 patients who had their LMA removed before the return of airway reflexes was 2.6% and was significantly better than the 10.9% incidence of complications (coughing, biting of the LMA, breath-holding, laryngeal spasm, excessive secretions, and retching) when the LMA was removed after the return of airway reflexes. Laffon et aZ.5 prospectively assessed the effect of anesthetized removal tle~sus awake removal of LMA in children. They observed an exceptional incidence (40%) of respiratory complications after LMA removal, which was signiflcantly greater in the awake group (53% V.X 27%). The authors attributed the unacceptably high incidence of airway complications with the LMA removal to inexperience with the device.6 Central to this study are the definitions of the “deep” verfus “awake” patient groups. We felt that the essential distinguishing feature between the study groups was the presence or absence of protective airway reflexes. Accordingly, we designed the study to create one group of patients who had intact airway reflexes and one in which patients had no protective airway reflexes. Due to the wide range of ages included in the study (1.5 to 15 years), 6
J. Clin. Anesth., vol. 9, Februan/ 1997
simple reporting of end-tidal halothane concentration at the time of LMA removal would not allow an accurate, objective assessment of depth of anesthesia among patients because the minimum alveolar concentration (MAC) of halothane varies considerably over this age range. Rather, we elected to refer to the “deep” group as those patients who underwent LMA removal at a surgical plane of anesthesia, while patients in the “awake” group exhibited purposeful movement, including swallowing, prior to LMA removal. In dividing the patients in this manner, we were confident that we had created one group of patients whose Lh4A was removed in the absence of protective airway reflexes and one group whose airway reflexes had returned at the time of LMA removal. The nature of the postoperative airway problems documented during this investigation varied. For example, an SpO, level less than 90% has much greater clinical significance than excessive salivation. When comparing the incidence of problems between the groups, weight was not given to the clinical significance of the various problems. A more detailed analysis of the events of clinical relevance, such as oxygen desaturation, did not reveal a difference between the groups. Many, but not all, of the potential problems associated with removal of an LMA were included in this study. The problems followed were those that had been previously investigated. Adding or subtracting problems from this list would preclude comparison of our results to those of others. The problems assessed were mostly objective phenomena not associated with significant interrater variability. Excessive salivation was included in the current investigation because it had been noted by others; however, it is a subjective event and cannot be reliably quantified. In conclusion, based on the findings of this study, we cannot recommend one method of LMA removal over the other, because both have an acceptably low incidence of complications. Our current clinical practice remains un-
200
72
74
76
78
80 82 84 86 88 90 92 LOWEST OXYGEN SATURATION
94
96
98 100
1. Distribution of lowest hemoglobin oxygen saturation (%) after removal of the Laryngeal mask Airway from the subjects.
Figure
LMA in children: Splinter and Reid
altered. Children are either deeply anesthetized when the LMA is removed.
or awake
deeply anaesthetized versus awake patients. Can JAnaesth 1995;42: 1113-6.
2. Mason DG, Bingham RM: The laryngeal mask airway in children.
Acknowledgments We thank our colleagues in anaesthesia and nursing for their cooperation and advice during this study. We also wish to thank Ms. Nancy Bye-Carson and Ms. Tina Subissati for their significant help in conducting this investigation. This research was supported in part by a grant from the Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
References 1. Gataure PS, Latto IP, Rust S: Complications associated with removal of the laryngeal mask airway: a comparison of removal in
Anaesthesia 1990;45:760-3. 3. Reddy SV, Win N: Brain laryngeal mask-study in 50 spontaneously breathing patients. Singapore Med J 1990;31:338-40. 4. McGinn G, Haynes SR, Morton NS: An evaluation of the laryngeal mask airway during routine paediatric anaesthesia. Paediah Anaesth 1993;3:23-8. 5. Laffon M, Plaud B, Dubousset AM, Ben Haj’hmida R, Ecoffey C: Removal of laryngeal mask airway: airway complications in children, anaesthetized versus awake. Pediatr Anaesth 1994;4:35-7. 6. Laffon M, Plaud B, Dubousset AM, Ben Haj’hmida R, Ecoffey C: Removal of laryngeal mask airway: airway complications in children, anaesthetized versus awake [Letter] Pediatr Am&h 1994;4: 272.
J. Clin. Anesth., vol. 9, February 1997
7
Original Contributions Removal of the Laryngeal Mask Airway in Children: Deep Anesthesia versus Awake William M. Splinter, MD, FRCPC,* Craig W. Reid, MD, FRCPC* Department Department
of Anaesthesia, Children’s Hospital of Eastern Ontario, Ottawa, and of Anaesthesia, University of Ottawa, Ottawa, Ontario, Canada.
Study Objective: To compare the incidence of adverse airway euents identified with removal of the laryngeal mask airway (LMA) f rom an awake child or from a child before his or her airway reflexes had returned. Design: Prospective, randomized study. Setting: University-affiliated children’s hospital. Patients: 333 ASA physical status I and II patients ages 1.5 to 15 years undergoing elective surgery. Interventions: At the time of removal of the LMA at the end of surgery, patients were anesthetized or had intact airway reflexes. Measurements and Main Results: Any ainuay problems occurring within 15 minutes of LMA removal were recorded. These problems included airway obstruction (laryngeal spasm and biting of the LMA), peripheral hemoglobin oxygen saturation less than 90%, strider requiring manipulation of the airway, vomiting, retching, and excessive salivation. Airway problems occurred after Lh44 removal among 23 children who had their LMA removed prior to return of airway reflexes, and among 13 subjects who had their IM removed afer the return of airway reflexes. Conclusion: Removal of the LMA during anesthesia and afte-r return of airway reflexes results in a similar inn’dence of airway problems in children. 0 1997 by Elsevier Science Inc. *Assistant Professor
Keywords:
Address correspondence to Dr. Splinter at the Department of Anaesthesia, Children’s Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, Ontario, Canada KIH 8Ll.
Introduction
Supported by a grant from the Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada. Received for publication October 11, 1995; revised manuscript accepted for publication April 16, 1996. *Brain AlJ: Instruction
The Intavent
Manual.
Intavent Ltd., 1991.
Lmyngeal
Mask Airway
Henley-on-Thames,
UK:
Anesthesia,
pediatric;
equipment:
Laryngeal
Mask Airway.
For many operative procedures, standard intraoperative airway management includes the insertion of a laryngeal mask airway (LMA). The optimal time to remove this airway is not known. Brain,* who invented the device, and the manufacturer recommend that the LMA be removed “awake”; that is, after the patient’s airway reflexes have returned. In contrast, Gataure et al.,’ concluded that it may be safer to remove the LMA while adult patients are deeply anesthetized. The reported incidence of problems with removal of the LMA after the patient has awakened is 10% to 53%, while the incidence after removal from the anesthetized, “deep” patient has varied from 2.6% to 27%.ie5 McGinn et al4 and
Journal of Clinical Anesthesia 94-7, 1997 0 1997 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0952-8180/97/$17.00 PI1 SO952-8180(96)00217-6
LMA
Laffon et al.’ compared removal of the LMA from the awake patient versus the deeply anesthetized patient, and found that patients who had their LMA removed while they were awake had more problems than patients who had the LMA extracted while anesthetized. This result disagrees with Brain’s recommendations. Unfortunately, both of these studies had flaws, which included a lack of randomization by McGinn et aL4 and, in Laffon et al.‘s study,5 the LMA removal was performed by inexperienced users. The purpose of our prospective, randomized study of children was to compare the incidence of adverse events associated with removal of the LMA either from the deeply anesthetized or awake patient.
Materials
and Methods
Following Research Ethics Committee of the Children’s Hospital of Eastern Ontario approval and parental consent, 333 healthy ASA physical status I and II patients ages 1.5 to 15 years were enrolled into this randomized, singleblind study. Patients undergoing airway surgery, or suffering from any disease that may affect airway reflexes, including recent upper respiratory tract infection or symptomatic asthma, were excluded. The patients were randomly assigned to one of the two study groups via a computer-generated random numbers table. The two groups were similar, except for the depth of anesthesia at the time of removal of the LMA, which was either before the return of airway reflexes (deep anesthesia) or after the patient had awakened and had intact airway reflexes. Following the application of standard anesthesia monitoring, the induction of anesthesia was by inhalation of halothane and nitrous oxide (N,O) or intravenously (IV) with propofol. A standard, nonreinforced LMA was inserted after induction of anesthesia. The appropriately sized, lubricated (2% lidocaine jelly) LMA was inserted in accordance with published guidelines4 A bite block was inserted with each LMA. Maintenance of anesthesia was primarily with N,O and halothane. Older patients received isoflurane instead of halothane. Patients received IV opioids and were administered regional anesthetics when clinically indicated. In the deep anesthesia group, a surgical plane of anesthesia was maintained until the or-opharynx had been gently suctioned to prevent inadvertent aspiration of pharyngeal contents, at which time the LMA was removed and the halothane was discontinued. Patients in the awake group were transferred to the recovery room and their LMA was removed by the nursing staff once they were exhibiting purposeful movements, including swallowing, as an indication of the return of airway protective reflexes. All persons who removed the LMA were experienced anesthesiologists or recovery room nursing staff. Prior to removal of the LMA, we made no special inter-
and Reid
Results Although we enroled 333 patients into this study, 25 patients were subsequently removed from the study because a Lh4A was not used (n = 17) or surgery was cancelled (n = 8). The primary reason for not using the LMA was lack of availability of the appropriately-sized LMA. The groups were similar with respect to age, weight, induction technique, length of anesthesia, and peripheral hemoglobin SpO, immediately before LMA removal (Table 1). The LMA was removed 1 f 3 minutes and 12 + 6 minutes (means f SD) after surgery was completed for the deep and awake groups, respectively. The laryngeal cuff was not deflated before LMA removal for 47 of the patients in the deep group and 10 patients in the awake group. An adverse event associated with LMA removal was noted in 36 patients. Problems occurred in 23 patients who had their LMA removed before the return of airway reflexes, while 13 patients who had removal of their LMA awake in the recovery room had a problem. The incidence of problems was not altered by the decision to have the LMA cuff inflated or not at the time of removal. The lowest SpO, level was similar between the groups studied (Table 2). Nine patients developed an SpO, of less than 90%, 3 in the “deep” removal group and 6 in the “awake” removal group (Figure 1). All four cases of laryngospasm
Table 1. Demographic Data Group
(~4
Weight (kg) Anesthesia time (min) Instruction
+linter
ventions, such as the administration of IV lidocaine or opioids, to blunt airway responses. Patients were observed by an anesthesiologist or recovery room nurse and monitored with a pulse oximeter after LMA removal. Any problems relating to the airway were recorded for 15 minutes after LMA removal. Specific problems noted by the observers included any airway obstruction (laryngeal spasm and biting of the airway), peripheral hemoglobin oxygen saturation (SpO,) less than 90%, stridor requiring manipulation of the airway, vomiting, retching, and/or excessive salivation. All problems were treated in the routine fashion. The remainder of the postoperative care was not altered by this study. Demographic data were assessed with Student’s t-test and Chi-square analysis, where appropriate. The incidence of problems was compared with Fisher’s exact test or Chisquare analysis, where relevant. Sample size was based on the following assumptions: an acceptable difference between the groups of 10% (5% us. 15%), a power of SO%, and a tolerated chance of a Type I error of 5%.
&e
*Brain AIJ: The Intavent Lmyngzal Mask Airnay Henley-on-Thames, UK: Intavent Ltd., 1991.
in childrat
Deep
Awake
6.1154 f 3.8 24k14 46+23
6.9156 i 4.0 28+ 17 47*23
Manual.
Note: Data are means f SD.
J. Clin. Anesth., vol. 9, February
1997
5
Original Contributions
Table 2. Recovery and Problems with Laryngeal Mask Airway Removal Group Problems Lowest hemoglobin spa, (%I Incidence of hemoglobin spo, < 90% Stridor Laryngospasm Breath holding Retching, vomiting Excessive salivation
Deep
Awake
23/155
13/155
98 + 3
98 k 4
>0.5
3/155 16 3 3 2 1
6/155 6 1 4 2 0
>0.5 0.14* 20.5 >0.5 >0.5 >0.5
p-V&U?
0.07
*Chi-square analysis, pvalue listed is after due consideration of multiple testing. SpO, = oxygen saturation as measured by pulse oximetry.
responded to continuous positive simple airway support measures.
airway
pressure
and
Discussion Removal of the LMA before or after return of airway reflexes resulted in a similar incidence of postoperative airway problems. The overall incidence of problems was 12%, which is similar to previous investigations,‘4 except Laffon et ~1.~Mason and Bingham’ observed a 13% incidence of problems (coughing, biting, laryngospasm, retching, vomiting) among children during awake removal. These events were minor in nature and promptly resolved. Reddy and Win’ noted a 20% incidence of problems (clenching of teeth, excessive salivation, and vomiting) associated with LMA removal from 50 patients. McGinn et aL4 investigated several aspects of the usage of a LMA, which included timing the removal of the airway. They studied 211 children in a nonrandomized fashion. The incidence of adverse events among the 76 patients who had their LMA removed before the return of airway reflexes was 2.6% and was significantly better than the 10.9% incidence of complications (coughing, biting of the LMA, breath-holding, laryngeal spasm, excessive secretions, and retching) when the LMA was removed after the return of airway reflexes. Laffon et aZ.5 prospectively assessed the effect of anesthetized removal tle~sus awake removal of LMA in children. They observed an exceptional incidence (40%) of respiratory complications after LMA removal, which was signiflcantly greater in the awake group (53% V.X 27%). The authors attributed the unacceptably high incidence of airway complications with the LMA removal to inexperience with the device.6 Central to this study are the definitions of the “deep” verfus “awake” patient groups. We felt that the essential distinguishing feature between the study groups was the presence or absence of protective airway reflexes. Accordingly, we designed the study to create one group of patients who had intact airway reflexes and one in which patients had no protective airway reflexes. Due to the wide range of ages included in the study (1.5 to 15 years), 6
J. Clin. Anesth., vol. 9, Februan/ 1997
simple reporting of end-tidal halothane concentration at the time of LMA removal would not allow an accurate, objective assessment of depth of anesthesia among patients because the minimum alveolar concentration (MAC) of halothane varies considerably over this age range. Rather, we elected to refer to the “deep” group as those patients who underwent LMA removal at a surgical plane of anesthesia, while patients in the “awake” group exhibited purposeful movement, including swallowing, prior to LMA removal. In dividing the patients in this manner, we were confident that we had created one group of patients whose Lh4A was removed in the absence of protective airway reflexes and one group whose airway reflexes had returned at the time of LMA removal. The nature of the postoperative airway problems documented during this investigation varied. For example, an SpO, level less than 90% has much greater clinical significance than excessive salivation. When comparing the incidence of problems between the groups, weight was not given to the clinical significance of the various problems. A more detailed analysis of the events of clinical relevance, such as oxygen desaturation, did not reveal a difference between the groups. Many, but not all, of the potential problems associated with removal of an LMA were included in this study. The problems followed were those that had been previously investigated. Adding or subtracting problems from this list would preclude comparison of our results to those of others. The problems assessed were mostly objective phenomena not associated with significant interrater variability. Excessive salivation was included in the current investigation because it had been noted by others; however, it is a subjective event and cannot be reliably quantified. In conclusion, based on the findings of this study, we cannot recommend one method of LMA removal over the other, because both have an acceptably low incidence of complications. Our current clinical practice remains un-
200
72
74
76
78
80 82 84 86 88 90 92 LOWEST OXYGEN SATURATION
94
96
98 100
1. Distribution of lowest hemoglobin oxygen saturation (%) after removal of the Laryngeal mask Airway from the subjects.
Figure
LMA in children: Splinter and Reid
altered. Children are either deeply anesthetized when the LMA is removed.
or awake
deeply anaesthetized versus awake patients. Can JAnaesth 1995;42: 1113-6.
2. Mason DG, Bingham RM: The laryngeal mask airway in children.
Acknowledgments We thank our colleagues in anaesthesia and nursing for their cooperation and advice during this study. We also wish to thank Ms. Nancy Bye-Carson and Ms. Tina Subissati for their significant help in conducting this investigation. This research was supported in part by a grant from the Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
References 1. Gataure PS, Latto IP, Rust S: Complications associated with removal of the laryngeal mask airway: a comparison of removal in
Anaesthesia 1990;45:760-3. 3. Reddy SV, Win N: Brain laryngeal mask-study in 50 spontaneously breathing patients. Singapore Med J 1990;31:338-40. 4. McGinn G, Haynes SR, Morton NS: An evaluation of the laryngeal mask airway during routine paediatric anaesthesia. Paediah Anaesth 1993;3:23-8. 5. Laffon M, Plaud B, Dubousset AM, Ben Haj’hmida R, Ecoffey C: Removal of laryngeal mask airway: airway complications in children, anaesthetized versus awake. Pediatr Anaesth 1994;4:35-7. 6. Laffon M, Plaud B, Dubousset AM, Ben Haj’hmida R, Ecoffey C: Removal of laryngeal mask airway: airway complications in children, anaesthetized versus awake [Letter] Pediatr Am&h 1994;4: 272.
J. Clin. Anesth., vol. 9, February 1997
7