Anesth Analg 57 :63-66. 1978
Cook and Fischer
63
Characteristics of Succi nylcholine Neurom uscula r Blockade in Neonates DAVID R. COOK, MD* CARL G. FISCHER, M D t Pittsburgh, Pennsylvania$
The neuromuscular response of 10 infants to train-of-four electrical stimuli was examined during anesthesia with Nz0-02-halothane and after 1.5 mg/kg of succinylcholine IV. The ulnar nerve was stimulated electrically with a Grass S88 SIU at the wrist; the resultant force of thumb adduction was recorded. Trains-of-four, 2-Hz, supramaximal, square stimulating pulses (0.1 m/sec) were applied every 12 seconds. The maximum twitch depression following injection of succinylcholine and t h e train-of-four ratio were noted for the control period, at 25 percent neuromuscular transmission (Tz5), 50 percent neuromuscular transmission (TJo),and 90 percent transmission ( T d . The degree of neuromuscular blockade following succinylcholine was calculated by comparing the height of the 1st twitch of the train of stimuli to the height of the 1st twitch of the train of stimuli during anesthesia alone.
N
lluring anesthesia and before administration of succinylcholine the train-of-four ratio averaged 0.92, a ratio comparable to that reported in adults during similar anesthesia. The average maximum neuromuscular blockade after 1.5 mg/kg succinylcholine was 91.1 percent. A t TZ6 the train-of-four ratio averaged 0.72; at T , the ratio averaged 0.79; and a t T, the ratio averaged 0.87. Using the criteria for succinylcholine phase I1 neuromuscular block suggested by Lee, no infant developed a phase I1 block with a n initial dose of succinylcholine of 1.5 mg/kg. Key Words-NEUROMUSCULAR RELAXANTS, succinylcholine. ANESTHESIA, pediatric.
require more depolarizing neu- muscular blockade as compared to adults romuscular relaxants such as decame- because of the phase I1 block.5 However, thoniuml and succinylcholine2-4on a weight neither of these hypotheses was documented. basis than do adults to achieve equal neuroSince gros fasciculations are rarely seen muscular blockade. The initial characteris- in neonates following succinylcholine admintics of the neuromuscular blockade with istration and since pseudocholinesterase depolarizing relaxants may also differ be- levels in neonates are about one-half those tween infants and adults. For example, of the adult,6 we wondered if the neonate Churchill-Davidson and Wise] noted many had an initial phase I1 block following a characteristics of a phase I1 block in neo- paralyzing dose of succinylcholine. Lee7 nates following a paralyzing dose of deca- recently characterized phase I and phase I1 methonium. They suggested that neonates of neuromuscular block in adult man followdevelop a phase 11block following an initial ing succinylcholine on the basis of train-ofdose of succinylcholine. Wylie and Chur- four ratios (the ratio of the height of the chill-Davidson further suggested that neo- 4th twitch response to the height of the 1st nates would have slightly prolonged neuro- twitch response during application of 4 EONATES
*Associate Professor of Clinical Anesthesiology ?Associate Professor of Anesthesiology and Pediatrics, University of Cincinnati School of Medicine $Departments of Anesthesiology, Children's Hospital of Pittsburgh and University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania Presented at the Anesthesiology Sections of the American Academy of Pediatrics, April 1977 Accepted for publication: July 25, 1977
64
Anesth A n d g 57 :63-66, 1978
Succinylcholine Block in Neonates
2-Hz supramaximal square-wave stimuli of 0.1 m/sec) .
Anesthesia was induced and maintained with N,O-0,-halothane for the duration of the study. Inspired concentrations of halothane By avoiding tetanic stimulation, the na- during the study ranged from 1.5 to 2.0 perture of neuromuscular blockade can be cent. Neither the alveolar levels of haloassessed as often as every 12 seconds.6-8 thane nor arterial blood gases were measDuring phase I block the train-of-four ratios ured. However, respiration was assisted or were high, ie, 0.7 to 0.9; during phase I1 controlled as necessary in an attempt to block they were low, ie, 0.3 or less. After a maintain eucarbia. All patients were euthertotal dose of 3 to 5 mg/kg of succinylcho- mic at the time of the study. line, phase I1 block was evident in all patients studied by Lee during halothane anThe neuromuscular blocking effects of esthesia. The transition from phase I to succinylcholine were monitored in a standphase I1 block was abrupt as the total dose ard way by stimulating the ulnar nerve and of succinylcholine increased. The transition recording the twitch height.8-10 Sterile 25in an individual adult occurred with an in- gauge metal needles were placed subcutanecrease in the total dose of succinylcholine ously close to the ulnar nerve at the wrist. of 1 to 2 mg/kg. Trains-of-four, 2 Hz, supramaximal, square stimulating pulses (0.1m/sec) were applied The present study defines in neonates the every 12 seconds from a Grass S88 stimulacharacteristics of neuromuscular blockade tion isolation unit. A Grass FT-03 force-disfollowing a paralyzing dose of succinylcho- placement transducer connected to a string line (1.5 mg/kg) using train-of-four criteria. with fixed tension was secured to the thumb by means of a small wooden applicator. The METHODS AND MATERIAL forearm was taped to a special armboard a t Ten infants, born at or near term, having the fingers, wrist, and mid-forearm to preoperations requiring general endotracheal vent rotation of the hand. The transducer anesthesia were studied. None had electro- was aligned parallel to the fully abducted lyte disturbances nor apparent volume de- thumb. The electrical signal resulting from ficiencies. The age and weight of each infant thumb adduction was amplified and recorded on a Hewlett-Packard paper recorder. are recorded in the table. Atropine (0.03mg/kg) was given IM 30 minutes prior to induction of anesthesia.
After stabilization of the twitch height and after I V atropine (0.1 mg), succinyl-
TABLE Train-of-Four Ratios in Anesthetized Neonates Before and After 1.5 mg/kg Succinylcholine Age
Weiaht
Patient
Rotio after succinylcholine
Rotio before reloxant
TZK*
TSO*
T0o'
1
1.03
0.73
0.82
0.88
IDovs)
1
3.5
2
3.8
6
1.06
0.61
0.88
0.95
3
2.5
10
0.87
0.79
0.88
0.95
4
3.1
14
0.67
0.40
0.50
0.50
5
3.8
1
0.96
0.64
0.83
1.00
6
3.3
3
0.96
1.00
0.98
0.95
7
2.3
1
0.79
0.63
0.75
0.77
8
3.1
1
1.00
1.00
0.83
0.91
0.85
0.94
9
4 .O
30
1.00
0.80
10
3.2
28
1.00
0.64
0.79
0.90
Mean rt SD
3.3 & 0.9
9.5 2 11.2
0.92 r 0.20
0.72 2 0.181
0.79 2 0.22t
0.87 & 0.15t
~~~
*T,,, T,,, and T,, represent 25, 50, and 90 percent neuromuscular transmission, respectively. tp
Cook and Fischer
63
Characteristics of Succi nylcholine Neurom uscula r Blockade in Neonates DAVID R. COOK, MD* CARL G. FISCHER, M D t Pittsburgh, Pennsylvania$
The neuromuscular response of 10 infants to train-of-four electrical stimuli was examined during anesthesia with Nz0-02-halothane and after 1.5 mg/kg of succinylcholine IV. The ulnar nerve was stimulated electrically with a Grass S88 SIU at the wrist; the resultant force of thumb adduction was recorded. Trains-of-four, 2-Hz, supramaximal, square stimulating pulses (0.1 m/sec) were applied every 12 seconds. The maximum twitch depression following injection of succinylcholine and t h e train-of-four ratio were noted for the control period, at 25 percent neuromuscular transmission (Tz5), 50 percent neuromuscular transmission (TJo),and 90 percent transmission ( T d . The degree of neuromuscular blockade following succinylcholine was calculated by comparing the height of the 1st twitch of the train of stimuli to the height of the 1st twitch of the train of stimuli during anesthesia alone.
N
lluring anesthesia and before administration of succinylcholine the train-of-four ratio averaged 0.92, a ratio comparable to that reported in adults during similar anesthesia. The average maximum neuromuscular blockade after 1.5 mg/kg succinylcholine was 91.1 percent. A t TZ6 the train-of-four ratio averaged 0.72; at T , the ratio averaged 0.79; and a t T, the ratio averaged 0.87. Using the criteria for succinylcholine phase I1 neuromuscular block suggested by Lee, no infant developed a phase I1 block with a n initial dose of succinylcholine of 1.5 mg/kg. Key Words-NEUROMUSCULAR RELAXANTS, succinylcholine. ANESTHESIA, pediatric.
require more depolarizing neu- muscular blockade as compared to adults romuscular relaxants such as decame- because of the phase I1 block.5 However, thoniuml and succinylcholine2-4on a weight neither of these hypotheses was documented. basis than do adults to achieve equal neuroSince gros fasciculations are rarely seen muscular blockade. The initial characteris- in neonates following succinylcholine admintics of the neuromuscular blockade with istration and since pseudocholinesterase depolarizing relaxants may also differ be- levels in neonates are about one-half those tween infants and adults. For example, of the adult,6 we wondered if the neonate Churchill-Davidson and Wise] noted many had an initial phase I1 block following a characteristics of a phase I1 block in neo- paralyzing dose of succinylcholine. Lee7 nates following a paralyzing dose of deca- recently characterized phase I and phase I1 methonium. They suggested that neonates of neuromuscular block in adult man followdevelop a phase 11block following an initial ing succinylcholine on the basis of train-ofdose of succinylcholine. Wylie and Chur- four ratios (the ratio of the height of the chill-Davidson further suggested that neo- 4th twitch response to the height of the 1st nates would have slightly prolonged neuro- twitch response during application of 4 EONATES
*Associate Professor of Clinical Anesthesiology ?Associate Professor of Anesthesiology and Pediatrics, University of Cincinnati School of Medicine $Departments of Anesthesiology, Children's Hospital of Pittsburgh and University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania Presented at the Anesthesiology Sections of the American Academy of Pediatrics, April 1977 Accepted for publication: July 25, 1977
64
Anesth A n d g 57 :63-66, 1978
Succinylcholine Block in Neonates
2-Hz supramaximal square-wave stimuli of 0.1 m/sec) .
Anesthesia was induced and maintained with N,O-0,-halothane for the duration of the study. Inspired concentrations of halothane By avoiding tetanic stimulation, the na- during the study ranged from 1.5 to 2.0 perture of neuromuscular blockade can be cent. Neither the alveolar levels of haloassessed as often as every 12 seconds.6-8 thane nor arterial blood gases were measDuring phase I block the train-of-four ratios ured. However, respiration was assisted or were high, ie, 0.7 to 0.9; during phase I1 controlled as necessary in an attempt to block they were low, ie, 0.3 or less. After a maintain eucarbia. All patients were euthertotal dose of 3 to 5 mg/kg of succinylcho- mic at the time of the study. line, phase I1 block was evident in all patients studied by Lee during halothane anThe neuromuscular blocking effects of esthesia. The transition from phase I to succinylcholine were monitored in a standphase I1 block was abrupt as the total dose ard way by stimulating the ulnar nerve and of succinylcholine increased. The transition recording the twitch height.8-10 Sterile 25in an individual adult occurred with an in- gauge metal needles were placed subcutanecrease in the total dose of succinylcholine ously close to the ulnar nerve at the wrist. of 1 to 2 mg/kg. Trains-of-four, 2 Hz, supramaximal, square stimulating pulses (0.1m/sec) were applied The present study defines in neonates the every 12 seconds from a Grass S88 stimulacharacteristics of neuromuscular blockade tion isolation unit. A Grass FT-03 force-disfollowing a paralyzing dose of succinylcho- placement transducer connected to a string line (1.5 mg/kg) using train-of-four criteria. with fixed tension was secured to the thumb by means of a small wooden applicator. The METHODS AND MATERIAL forearm was taped to a special armboard a t Ten infants, born at or near term, having the fingers, wrist, and mid-forearm to preoperations requiring general endotracheal vent rotation of the hand. The transducer anesthesia were studied. None had electro- was aligned parallel to the fully abducted lyte disturbances nor apparent volume de- thumb. The electrical signal resulting from ficiencies. The age and weight of each infant thumb adduction was amplified and recorded on a Hewlett-Packard paper recorder. are recorded in the table. Atropine (0.03mg/kg) was given IM 30 minutes prior to induction of anesthesia.
After stabilization of the twitch height and after I V atropine (0.1 mg), succinyl-
TABLE Train-of-Four Ratios in Anesthetized Neonates Before and After 1.5 mg/kg Succinylcholine Age
Weiaht
Patient
Rotio after succinylcholine
Rotio before reloxant
TZK*
TSO*
T0o'
1
1.03
0.73
0.82
0.88
IDovs)
1
3.5
2
3.8
6
1.06
0.61
0.88
0.95
3
2.5
10
0.87
0.79
0.88
0.95
4
3.1
14
0.67
0.40
0.50
0.50
5
3.8
1
0.96
0.64
0.83
1.00
6
3.3
3
0.96
1.00
0.98
0.95
7
2.3
1
0.79
0.63
0.75
0.77
8
3.1
1
1.00
1.00
0.83
0.91
0.85
0.94
9
4 .O
30
1.00
0.80
10
3.2
28
1.00
0.64
0.79
0.90
Mean rt SD
3.3 & 0.9
9.5 2 11.2
0.92 r 0.20
0.72 2 0.181
0.79 2 0.22t
0.87 & 0.15t
~~~
*T,,, T,,, and T,, represent 25, 50, and 90 percent neuromuscular transmission, respectively. tp
