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Recognizing hypoventilation in the recovery room
Recognizing hypoventilation in the recovery room Lisa V Sigg, RN Linda L Fallucca, RN
270
ypoventilation in patients in the recovery room is a serious problem. Respiratory depression occurs frequently because of the high doses of narcotics used to maintain the proper level of anesthesia during surgery and because of the residual effects of neuromuscular blocking agents. The recovery room nurse must be able to recognize the onset of hypoventilation. An assessment tool was developed to help the recovery room nurse monitor the patient’s condition and recognize early warnings of respiratory depression. If respiratory depression can be predicted, interventions will prevent respiratory hypoventilation and arrest. Causes of hypoventilation. The use of balanced or narcotic anesthesia has increased the incidence of respiratory depression. This technique, which combines the use of nitrous oxide with a narcotic and, if necessary, a muscle relaxant, is one of the most widely used anesthesia methods. This technique gained popularity in the 1960s when morphine was used for open-heart surgery, and fentanyl, a short-acting narcotic, was developed especially for use with anesthesia. A well-known side effect of balanced anesthesia is hypoventilation. Although there are multiple reasons for respiratory depression, the four most common are: (1)the amount of narcotic used; (2) the length of surgery; (3) decreased stimulation after surgery and after admission to the recovery room; and (4) the amount of carbon dioxide crossing the blood brain barrier. The patient’s physical condition also affects the metabolism of narcotics. Elderly and sick patients, especially with liver disease, metabolize narcotics slowly and are at risk for prolonged respiratory depression. Pharmacology of balanced anesthesia. All narcotics have similar action. They produce analgesia, respiratory depres-
AORN Journal, August 1983, Val 38,No 2
sion, gastrointestinal spasm, and other morphine-like effects. Narcotic activity is diffuse, affecting the central nervous system including the spinal cord, brain stem, thalamus, hypothalamus, diencephalon, cortex, reticular system, and gamma neurons. The exact mechanism of action is unclear. It is known, however, that narcotics affect the release of neurotransmitters and, most likely, affect the release of acetylcholine. The narcotics seem to inhibit the release of catecholamine or neurotransmitters from certain peripheral neurons and increase the release of catecholamine in the central nervous system. It appears that narcotics do not affect a particular receptor but affect heterogeneous receptors. Narcot-
Lisa V Sigg
Linda L Fallucca
Lisa V Sigg, RN, MSN, is a practitioner/ teacher in the recovery room and operating room at Rush-Presbyterian-StLuke’s Medical Center, Chicago, and an instructor at Rush University College of Nursing. A diploma graduate of Presbyterian-StLuke’s HospitalSchool of Nursing, she earned a BA at Northeastern Illinois University, Chicago, and an MSN from Rush University College of Nursing. Linda L Faiiucca, RN, MSN, is a clinical specialist, surgical nursing, Mt Sinai Hospital, Chicago, and formerly a staff nurse in the recovery room at Rush-Presbyterian-St Luke’s Medical Center. She has a BSN from DePaul University, Chicago, and an MSN from Rush University School of Nursing.
272
ics increase the pain threshold and alter actions in the limbic system without altering other sensory modalities.’ Narcotics used in anesthesia include morphine, meperidine (Demerol), and fentanyl, the most widely used. Fentanyl is a potent narcotic analgesic with a rapid onset and a short duration of action. The average duration of action is 30 to 60 minutes, and the total effect lasts from two to four hours. Fentanyl is 80 to 180 times as potent as morphine.2 Fentanyl depresses respirations by: (1) directly depressing the respiratory center; (2) decreasing the response of the carotid body and aortic chemoreceptors to elevated carbon dioxide levels; (3) decreasing ciliary action in the bronchial tree; and (4) increasing bronchial tonus. The respiratory system is depressed by reducing the responsiveness of the brain stem respiratory center to carbon dioxide increases. Fentanyl also depresses the pontine and medullary centers involved in regulating respiratory rate and rhythm. After the administration of fentanyl, respiratory depression is seen as decreases in respiratory minute volume, rate, and tidal volume. This causes an increase in carbon dioxide in the blood, resulting in hypoxia and hyper~arbia.~ In balanced anesthesia, the two most frequently used neuromuscular blocking agents or muscle relaxants are pancuronium bromide and d-tubocurarine. Both are nondepolarizing neuromuscular blocking agents causing competitive inhibition at the myoneural junction. These two drugs combine with the cholinoceptive sites at the postjunctional membrane, blocking the transmitter action of acetylcholine and preventing the continuation of an impulse at the neuromuscular junction causing skeletal muscle paralysis. D-tubocurarine and pancuronium bromide are antagonized by acetylcholine, anticholinesterase drugs, and potassium.
AORN Journal, August 1983, Vol38, No 2
Neuromuscular blocking agents’ actions are increased by inhalation anesthetics, quinine, magnesium salts, hypokalemia, oat cell carcinoma, and certain antibiotics. D-tubocurarine and pancuronium bromide have no effect on consciousness, pain threshold, or functional action of the cerebrum because these drugs do not cross the blood-brain barrier. The most frequent adverse reaction to pancuronium bromide and d-tubocurarine is the extension of pharmacological actions beyond the time needed for anesthesia. Adverse reactions may vary from skeletal muscle weakness to profound and prolonged skeletal muscle relaxation resulting in respiratory insufficiency or apnea. The neuromuscular blocking agents cause paralysis of the intercostal muscles and the diaphragm. Death is caused by hypoxia secondary to respiratory muscle paralysis. Respiratory dysfunction may continue even after administration of anticholinesterase reversal agents. Satisfactory reversal of the blocking agents can be assessed by adequate muscle tone and respiration. A peripheral nerve stimulator may be used to monitor restoration of twitch height on an unconscious patient. The major difference between the two agents is that pancuronium bromide causes a slight rise in pulse rate, whereas d-tubocurarine causes a decrease in blood pressure due to the release of histamines. Pancuronium bromide is five times as potent as d-tubocurarine. Both drugs are primarily excreted through the urine.4 The increased use of balanced anesthesia has stimulated the development of naloxone, a narcotic antagonist. Narcotic antagonists are administered to correct respiratory depression and restore consciousness. Naloxone is the only narcotic antagonist that does not 274
depress respiratory action. Its action is not precisely known, but the most widely accepted theory is that naloxone competes with narcotics for the same receptor sites. Two problems may occur with use of naloxone. If the dose of naloxone is too high, the respiratory depression will be corrected, but there will be a loss of analgesia, leaving the patient in pain. The other problem is that respiratory depression can recur if the naloxone wears off before the narcotics. Often patients arrive in the recovery room without a reversal agent and are breathing adequately. But when the stimulation of the admission procedure is over, the patient will fall back asleep and hypoventilate if not further stimulated. Naloxone may then be given in the recovery room. Naloxone is not always the narcotic antagonist of choice, especially when the patient is recovering from a long procedure. The effect of naloxone is about 30 minutes, but the effect of the narcotic may last from 3 to 4 hours, and the patient then falls asleep and hypoventilates again. The effect of the narcotic may be more prolonged in the elderly because of decreases in liver function or enzymes.
Naloxone competes with narcotics for reception sites. The assessment tool. Using a threephased assessment tool, the recovery room nurse can prevent or predict the onset of respiratory depression. The assessment tool is used on admission and every 30 minutes thereafter for two hours, which is the average length of stay in the recovery room. The num-
AORN Journal, August 1983, Vol38, No 2
Fig 7
Assessment tool for hypoventilation from narcotic anesthesia in the RR Phase I Patient's name Find the description in each category that best fits the patient and circlethe number of points under the time of assessment. Add the number of points on each page, then add the two numbers together to get the patient's score. Check the interpretationto see if further assessment is neededat this time. If assessments must be made after 120 minutes, write the time at the top of the column.
Time of assessment Admission 30 60 90 120 Respiration rate respiratory ratelof 16 to 22 breathslmin respiratory ratelof 12 to 16 breaths/min respiratory ratelof less than 12 breaths/ minlor no spontaneous breathdover 1Umin
Discharge
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
0
0
0
0
0
0
0
0
Respiratory pattern regular respiratory pattern irregular respiratory pattern no spontaneous breathing
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1
0
Depth of respiration deep, full respirations shallow respiration no spontaneous breathing
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2
2
2
2
2
2
2
2
1
0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
Level of consciousness patient awake, alert patient arousable when called no auditory response from patient
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
ber of assessments after two hours depends on the patient's condition and the reasons for the prolonged stay in the recovery room. If the patient is stable, the assessments can be made hourly. If the patient is unstable or on a ven-
tilator, the assessments will continue until the patient recovers from anesthesia and is table.^ Phase I (Fig 1) is the standard admission assessment in the recovery room. This includes assessment of respiratory
Lung sounds bilateral breath soundslequal, clear abnormal, diminishedlor adventitous breath sounds no spontaneous breath sounds
216
AORN Journal, August 1983, Vol38, No 2
Color pink pale, dusky, blotchy, jaundice/ or other abnormal color cyanotic
2
2
2
2
2
2
2
2
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2
2
2
2
2
2
2
2
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
Blood pressure t 10% to 20% of preanesthetic level t 20% to 50% of preanesthetic level t 50% or more of preanesthetic level
Pulse
* 1 0 or less of preanesthetic range 2 1 0 to 20
of preanesthetic range t 20 or more of preanesthetic range Activity patient moves all four extremities/ voluntarily or on command patient moves two extremities/ voluntarily or on command patient does not move Physical status physical status 1 physical status 2 physical status 3 to 5
Interpretation of score 16 to 20 points: patient is at minimal risk for respiratory depression. 12to 16 points: possibility existsfor respiratory depression. Proceedto phase I1to check respiratory status. 1 to 12 points: patient is at high risk or may be hypoventilating. Proceed to phase 11. Watch closely.
rate, respiratory patterns, respiratory depth, lung sounds, level of consciousness, skin color, blood pressure, pulse, level of activity, and preoperative physical status. The patient’s preoperative physical
status influences the effects of narcotic anesthetics. The American Society of Anesthesiologists has five classifications. Physical status 1-the patient has no organic, physiologic, biochemical,
d) AORN Journal, August 1983,Vol38, No 2
277
Fig 2
Assessment tool for hypoventilation from narcotic anesthesia in the RR Phase II Patient's name Measurements of respiratory parameters are made using the Wright respirometer. Find the description in each category that best fits the patient and circle the number of points under the time of assessment. Add the number of pointsto get the patient's score. Check the interpretation to see if further assessment is needed at this time.
If assessments must still be made after 120 minutes, write the time at the top of the column. Time of assessment Admission 30 60 90 120
Discharge
Tidal volume 10 cdkg to more than 500 cc 8 to 10 cclkg or 300 to 500 cc 5 to 8 cclkg or under 300 cc
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
Minute ventilation 5to 7 L 3to5L 1to3L
2 1 0
2 1
2 1
2 1
2 1
2 1
2 1
2 1
0
0
0
0
0
0
0
Vital capacity 750 to 1200 cc 500 to 750 cc 500 cc or less
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1
Negative inspiratory force -15 cm H20 to -20 cm H20 -5 cm H20 to -15 cm H20 0 cm H20 to -5 cm H20
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
0
0
0
0
0
0
0
0
Respiratory rate 16 to 22 breathslmin 12 to 16 breathslmin 12 breathdmin or no spontaneous breathing
0
0
Interpretation of score 8 to 10 points: patient's respiratory status is good. 6 to 8 points: caution. Watch patient closely, encourage ventilation, and, if possible, obtain blood gas. 6 points: obtain blood gas and assist ventilation.
280
AORN Journal, August 1983, Vol38, No 2
psychiatric, or any type of system disturbance Physical stat'us 2-mild to moderate systemic disturbance or disease Physical status 3-severe systemic disturbance or disease Physical status &life-threatening severe systemic disorders Physical status 5-moribund patient with little chance of survival The Phase I1 assessment (Fig 2) is initiated when results of Phase I are inconclusive in predicting respiratory depression. Phase I1 measures tidal volume, minute volume, vital capacity, negative inspiratory force, and respiratory rate. Respiratory rate is probably most important because the volume of air is independent of the respiration rate, and the two together provide proper ventilation.s Tidal volume is the amount of air expired in one minute. Vital capacity is the greatest amount or volume of air that can be expired. Negative inspiratory force is a measure of the negative force required during normal ventilation to suck air into the alveolar ducts and sacs. A Wright respirometer and pressure manometer are used to make these assessments. The Wright respirometer measures tidal volume and minute volume accurately, and measures vital capacity within 10%. Both instruments are light and compact and can be attached to a mask placed over the patient's face or to the endotracheal tube. The Phase I11 assessment (Fig 3) is used only if there is question of hypoventilation and there is time for a blood gas analysis. Usually, blood gases are drawn after the initial problem has been treated and used to determine if the treatment is adequate. This assessment is performed by drawing an arterial blood sample and analyzing the blood gases to determine oxygen, POz, PC02, pH, and bicarbonate. This provides definite proof of respiratory 282
acidosis caused by hypoventilation as a result of narcotic anesthesia. Interventions. Treatment of hypoventilation depends on variables such as the patient's health, the amount of narcotic anesthesia given, the type of surgery, and the amount of muscle relaxants used. The Phase I assessment determines nursing actions. Each area is given a value of 0 to 2 points. The patient with a score from 16 to 20 is at minimal risk for hypoventilation. He requires only a face tent, high humidity oxygen, and a stirup regimen to stimulate deep breathing, coughing, and turning. All patients who receive general anesthesia should receive high humidity oxygen. The percentage of oxygen delivered depends on the institution and anesthesiologist and is usually between 40% and 60% with a flow of 6 L to 10 L. Usually, the higher the oxygen percentage, the lower the liter flow. Patients with chronic obstructive pulmonary disease usually require a lower percentage of oxygen because this stimulates them t o breathe. The patient with a score from 12 to 16 points should be examined for the need for ventilatory assistance. The nurse should then proceed to the Phase I1 as-
Treatment depends on a number of variables. sessment to check respiratory status. Patients who score between 12 and 16 need more frequent observation and stir-up regimens to prevent hypoventilation. The nurse should examine the anesthesia record to determine the last dose
AORN Journal, August 1983, Vol38, No 2
Fig 3
Assessment tool for hypoventilation from narcotic anesthesia in the RR Phase Ill Patient’s name
~
~~
~.
The arterial blood gas is a reliable way of diagnosing respiratory acidosis. Find the description that best fits the patient and enter the number of points under the time of assessment. Check the interpretation to see if further assessment is needed at this time. If assessments must still be made after 120 minutes, write the time at the top of the column.
If values do not correlate with those listed, especially the PCOZ,POn, and pH, the problem is not hypoventilationfrom narcotic anesthesia. It is a separate problem that requires diagnosis and treatment.
PH PCO2 PO2 HCOS Base excess
10 points 7.35 to 7.45 34 to 45 mm Hg 80 to 100 mm Hg 24? 1 mEq/L -1 to -2
Score Time of assessment Admission 30 60 90 120
8 points 7.30 to 7.35 45 to 55 mm Hg 60 to 80 mm Hg 2 4 t 3 mEq/L -2 to -5
6 points
< 7.30 > 55 mm Hg <60 mm Hg 2 4 t 6 mEq/L -5 to -7
Discharge
Interpretation of score 10 points: continue present therapy. 8 points: patient requires some increase in ventilation. 6 points: patient needs immediate ventilation.
of naloxone and narcotics. Some patients who receive naloxone before coming to the recovery room score 16 to 20 points on admission, but 10 to 30 minutes later, their score decreases to 12 to 16 points or lower because the naloxone does not last as long as the narcotic. Patients who score less than 12 points on the Phase I assessment are at high risk for hypoventilation. The nurse should then proceed to Phase I1 quickly and monitor the patient closely because this patient may need to be intubated and, if necessary, put on a T-piece or 284
ventilator. The nurse should then determine if the patient has received any naloxone in the operating room and when. Another dose may be needed. If no naloxone was administered, it can now be given to correct the problem of hypoventilation. However, if the patient has received excessive doses of naloxone, he may require ventilation, and if not intubated, the patient should be reintubated. As the naloxone wears off, some patients with respiratory depression may be given physostigmine salicylate (An-
AORN Journal, August 1983, Vol38, N o 2
tilerium). This drug is a nonspecific anticholinesterase that stimulates central and peripheral cholinergic receptor^.^ Physostigmine is used for patients who are agitated during emergence from anesthesia or who are unresponsive to naloxone. The Phase I1 assessment gives more reliable information on the patient's ventilation. If the patient scores between 8 and 10 points, his respiratory status is good. The stir-up regimen and oxygen are continued, and naloxone usage and need are evaluated. If the patient scores between 6 and 8 points, the nurse should watch the patient closely and, if possible, obtain an arterial blood gas sample. If the patient is intubated, the stir-up regimen should be continued. If the patient is not intubated, the nurse should prepare for possible administration of naloxone or reintubation. If additional doses of naloxone are given, the patient is watched for respiratory depression because the effects of naloxone may wear off before the narcotic. If possible, a blood gas analysis is obtained to determine the degree of hypoventilation and respiratory acidosis. If the patient scores below 6, the nurse should assist ventilation, prepare to reintubate, and have a ventilator available. A blood gas analysis should be obtained as soon as possible. In the Phase I11 assessment, if the patient scores 10 points, therapy continues as prescribed. If the patient is intubated and on the ventilator, he may progress to use of a T-piece, depending on the degree of wakefulness. This patient must be watched carefully for potential respiratory depression. If the patient scores only 8 points, more rigorous treatment is initiated. Naloxone is given or ventilation is assisted, or both. If the patient scores less than 6 points, immediately place the patient on ventilatory assistance. A score of 6 or less means the patient is hypoventilating.
This patient requires rigorous treatment to increase ventilation. He has severe respiratory acidosis and respiratory depression. Summary. This assessment tool assists the recovery room nurse to determine respiratory depression and hypoventilation. In Phase I, the nurse performs a general assessment and assigns values to them to describe the patient's respiratory status. Phase I1 assessments measure the patient's actual ventilations, determining that oxygen is getting to the lungs. In the Phase I11 assessment, the amount of oxygen entering the blood and going to the tissues is measured. This assessment tool can help the recovery room nurse predict, prevent, and treat hypoventilation or respiratory depression resulting from narcotic anesthesia. 0 Notes 1. J J Downes, R A Kemp, C J Lambertsen, "The magnitude and duration of respiratory depression due to fentanyl and meperidine in man," Journal of Pharmacology and ExperimentalTherapeutics 158 (1967) 416-420. 2. M H Harper et al, "The magnitude and duration of respiratory depression produced by fentanyl and fentanyl plus droperidol in man," Journal of Pharmacology and Experimental Therapeutics 199 (1976) 464-468. 3. J S Finch, T J deKornfeld, "Clinical investigations of the analgesic potency and respiratory depressant activity of fentanyl, a new narcotic analgesic," Journal of Clinical Pharmacology 7 (1967) 46-51. 4. L S Goodman, A Gilman, The Pharmacological Basic of Therapeutics, 5th ed (New York: Macmillan, 1975). 5. J A Aldrete, D Kroulike, "A postanesthesia recovery score," Anesthesia and Analgesiaxurrent Researches (November-December 1970) 924-933. 6. H C Churchill-Davidson, ed., Practice of Anaesthesia, 4th ed (Philadelphia:W B Saunders Co, 1978) 68. 7. V I Collins, Principles of Anesthesiology, 2nd ed (Philadelphia: Lea 8 Febinger, 1978). 8. R D Dripps, J E Eckenhoff, L D Vandem, Introduction to Anesthesia: The Principles of Safe Practice, 6th ed (Philadelphia: W B Saunders, 1982) 145-159.
AORN Journal, August 1983, Vol38, No 2
285
270
ypoventilation in patients in the recovery room is a serious problem. Respiratory depression occurs frequently because of the high doses of narcotics used to maintain the proper level of anesthesia during surgery and because of the residual effects of neuromuscular blocking agents. The recovery room nurse must be able to recognize the onset of hypoventilation. An assessment tool was developed to help the recovery room nurse monitor the patient’s condition and recognize early warnings of respiratory depression. If respiratory depression can be predicted, interventions will prevent respiratory hypoventilation and arrest. Causes of hypoventilation. The use of balanced or narcotic anesthesia has increased the incidence of respiratory depression. This technique, which combines the use of nitrous oxide with a narcotic and, if necessary, a muscle relaxant, is one of the most widely used anesthesia methods. This technique gained popularity in the 1960s when morphine was used for open-heart surgery, and fentanyl, a short-acting narcotic, was developed especially for use with anesthesia. A well-known side effect of balanced anesthesia is hypoventilation. Although there are multiple reasons for respiratory depression, the four most common are: (1)the amount of narcotic used; (2) the length of surgery; (3) decreased stimulation after surgery and after admission to the recovery room; and (4) the amount of carbon dioxide crossing the blood brain barrier. The patient’s physical condition also affects the metabolism of narcotics. Elderly and sick patients, especially with liver disease, metabolize narcotics slowly and are at risk for prolonged respiratory depression. Pharmacology of balanced anesthesia. All narcotics have similar action. They produce analgesia, respiratory depres-
AORN Journal, August 1983, Val 38,No 2
sion, gastrointestinal spasm, and other morphine-like effects. Narcotic activity is diffuse, affecting the central nervous system including the spinal cord, brain stem, thalamus, hypothalamus, diencephalon, cortex, reticular system, and gamma neurons. The exact mechanism of action is unclear. It is known, however, that narcotics affect the release of neurotransmitters and, most likely, affect the release of acetylcholine. The narcotics seem to inhibit the release of catecholamine or neurotransmitters from certain peripheral neurons and increase the release of catecholamine in the central nervous system. It appears that narcotics do not affect a particular receptor but affect heterogeneous receptors. Narcot-
Lisa V Sigg
Linda L Fallucca
Lisa V Sigg, RN, MSN, is a practitioner/ teacher in the recovery room and operating room at Rush-Presbyterian-StLuke’s Medical Center, Chicago, and an instructor at Rush University College of Nursing. A diploma graduate of Presbyterian-StLuke’s HospitalSchool of Nursing, she earned a BA at Northeastern Illinois University, Chicago, and an MSN from Rush University College of Nursing. Linda L Faiiucca, RN, MSN, is a clinical specialist, surgical nursing, Mt Sinai Hospital, Chicago, and formerly a staff nurse in the recovery room at Rush-Presbyterian-St Luke’s Medical Center. She has a BSN from DePaul University, Chicago, and an MSN from Rush University School of Nursing.
272
ics increase the pain threshold and alter actions in the limbic system without altering other sensory modalities.’ Narcotics used in anesthesia include morphine, meperidine (Demerol), and fentanyl, the most widely used. Fentanyl is a potent narcotic analgesic with a rapid onset and a short duration of action. The average duration of action is 30 to 60 minutes, and the total effect lasts from two to four hours. Fentanyl is 80 to 180 times as potent as morphine.2 Fentanyl depresses respirations by: (1) directly depressing the respiratory center; (2) decreasing the response of the carotid body and aortic chemoreceptors to elevated carbon dioxide levels; (3) decreasing ciliary action in the bronchial tree; and (4) increasing bronchial tonus. The respiratory system is depressed by reducing the responsiveness of the brain stem respiratory center to carbon dioxide increases. Fentanyl also depresses the pontine and medullary centers involved in regulating respiratory rate and rhythm. After the administration of fentanyl, respiratory depression is seen as decreases in respiratory minute volume, rate, and tidal volume. This causes an increase in carbon dioxide in the blood, resulting in hypoxia and hyper~arbia.~ In balanced anesthesia, the two most frequently used neuromuscular blocking agents or muscle relaxants are pancuronium bromide and d-tubocurarine. Both are nondepolarizing neuromuscular blocking agents causing competitive inhibition at the myoneural junction. These two drugs combine with the cholinoceptive sites at the postjunctional membrane, blocking the transmitter action of acetylcholine and preventing the continuation of an impulse at the neuromuscular junction causing skeletal muscle paralysis. D-tubocurarine and pancuronium bromide are antagonized by acetylcholine, anticholinesterase drugs, and potassium.
AORN Journal, August 1983, Vol38, No 2
Neuromuscular blocking agents’ actions are increased by inhalation anesthetics, quinine, magnesium salts, hypokalemia, oat cell carcinoma, and certain antibiotics. D-tubocurarine and pancuronium bromide have no effect on consciousness, pain threshold, or functional action of the cerebrum because these drugs do not cross the blood-brain barrier. The most frequent adverse reaction to pancuronium bromide and d-tubocurarine is the extension of pharmacological actions beyond the time needed for anesthesia. Adverse reactions may vary from skeletal muscle weakness to profound and prolonged skeletal muscle relaxation resulting in respiratory insufficiency or apnea. The neuromuscular blocking agents cause paralysis of the intercostal muscles and the diaphragm. Death is caused by hypoxia secondary to respiratory muscle paralysis. Respiratory dysfunction may continue even after administration of anticholinesterase reversal agents. Satisfactory reversal of the blocking agents can be assessed by adequate muscle tone and respiration. A peripheral nerve stimulator may be used to monitor restoration of twitch height on an unconscious patient. The major difference between the two agents is that pancuronium bromide causes a slight rise in pulse rate, whereas d-tubocurarine causes a decrease in blood pressure due to the release of histamines. Pancuronium bromide is five times as potent as d-tubocurarine. Both drugs are primarily excreted through the urine.4 The increased use of balanced anesthesia has stimulated the development of naloxone, a narcotic antagonist. Narcotic antagonists are administered to correct respiratory depression and restore consciousness. Naloxone is the only narcotic antagonist that does not 274
depress respiratory action. Its action is not precisely known, but the most widely accepted theory is that naloxone competes with narcotics for the same receptor sites. Two problems may occur with use of naloxone. If the dose of naloxone is too high, the respiratory depression will be corrected, but there will be a loss of analgesia, leaving the patient in pain. The other problem is that respiratory depression can recur if the naloxone wears off before the narcotics. Often patients arrive in the recovery room without a reversal agent and are breathing adequately. But when the stimulation of the admission procedure is over, the patient will fall back asleep and hypoventilate if not further stimulated. Naloxone may then be given in the recovery room. Naloxone is not always the narcotic antagonist of choice, especially when the patient is recovering from a long procedure. The effect of naloxone is about 30 minutes, but the effect of the narcotic may last from 3 to 4 hours, and the patient then falls asleep and hypoventilates again. The effect of the narcotic may be more prolonged in the elderly because of decreases in liver function or enzymes.
Naloxone competes with narcotics for reception sites. The assessment tool. Using a threephased assessment tool, the recovery room nurse can prevent or predict the onset of respiratory depression. The assessment tool is used on admission and every 30 minutes thereafter for two hours, which is the average length of stay in the recovery room. The num-
AORN Journal, August 1983, Vol38, No 2
Fig 7
Assessment tool for hypoventilation from narcotic anesthesia in the RR Phase I Patient's name Find the description in each category that best fits the patient and circlethe number of points under the time of assessment. Add the number of points on each page, then add the two numbers together to get the patient's score. Check the interpretationto see if further assessment is neededat this time. If assessments must be made after 120 minutes, write the time at the top of the column.
Time of assessment Admission 30 60 90 120 Respiration rate respiratory ratelof 16 to 22 breathslmin respiratory ratelof 12 to 16 breaths/min respiratory ratelof less than 12 breaths/ minlor no spontaneous breathdover 1Umin
Discharge
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
0
0
0
0
0
0
0
0
Respiratory pattern regular respiratory pattern irregular respiratory pattern no spontaneous breathing
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1
0
Depth of respiration deep, full respirations shallow respiration no spontaneous breathing
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2
2
2
2
2
2
2
2
1
0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
Level of consciousness patient awake, alert patient arousable when called no auditory response from patient
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
ber of assessments after two hours depends on the patient's condition and the reasons for the prolonged stay in the recovery room. If the patient is stable, the assessments can be made hourly. If the patient is unstable or on a ven-
tilator, the assessments will continue until the patient recovers from anesthesia and is table.^ Phase I (Fig 1) is the standard admission assessment in the recovery room. This includes assessment of respiratory
Lung sounds bilateral breath soundslequal, clear abnormal, diminishedlor adventitous breath sounds no spontaneous breath sounds
216
AORN Journal, August 1983, Vol38, No 2
Color pink pale, dusky, blotchy, jaundice/ or other abnormal color cyanotic
2
2
2
2
2
2
2
2
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2
2
2
2
2
2
2
2
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
Blood pressure t 10% to 20% of preanesthetic level t 20% to 50% of preanesthetic level t 50% or more of preanesthetic level
Pulse
* 1 0 or less of preanesthetic range 2 1 0 to 20
of preanesthetic range t 20 or more of preanesthetic range Activity patient moves all four extremities/ voluntarily or on command patient moves two extremities/ voluntarily or on command patient does not move Physical status physical status 1 physical status 2 physical status 3 to 5
Interpretation of score 16 to 20 points: patient is at minimal risk for respiratory depression. 12to 16 points: possibility existsfor respiratory depression. Proceedto phase I1to check respiratory status. 1 to 12 points: patient is at high risk or may be hypoventilating. Proceed to phase 11. Watch closely.
rate, respiratory patterns, respiratory depth, lung sounds, level of consciousness, skin color, blood pressure, pulse, level of activity, and preoperative physical status. The patient’s preoperative physical
status influences the effects of narcotic anesthetics. The American Society of Anesthesiologists has five classifications. Physical status 1-the patient has no organic, physiologic, biochemical,
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Fig 2
Assessment tool for hypoventilation from narcotic anesthesia in the RR Phase II Patient's name Measurements of respiratory parameters are made using the Wright respirometer. Find the description in each category that best fits the patient and circle the number of points under the time of assessment. Add the number of pointsto get the patient's score. Check the interpretation to see if further assessment is needed at this time.
If assessments must still be made after 120 minutes, write the time at the top of the column. Time of assessment Admission 30 60 90 120
Discharge
Tidal volume 10 cdkg to more than 500 cc 8 to 10 cclkg or 300 to 500 cc 5 to 8 cclkg or under 300 cc
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
Minute ventilation 5to 7 L 3to5L 1to3L
2 1 0
2 1
2 1
2 1
2 1
2 1
2 1
2 1
0
0
0
0
0
0
0
Vital capacity 750 to 1200 cc 500 to 750 cc 500 cc or less
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1
Negative inspiratory force -15 cm H20 to -20 cm H20 -5 cm H20 to -15 cm H20 0 cm H20 to -5 cm H20
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1 0
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
0
0
0
0
0
0
0
0
Respiratory rate 16 to 22 breathslmin 12 to 16 breathslmin 12 breathdmin or no spontaneous breathing
0
0
Interpretation of score 8 to 10 points: patient's respiratory status is good. 6 to 8 points: caution. Watch patient closely, encourage ventilation, and, if possible, obtain blood gas. 6 points: obtain blood gas and assist ventilation.
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psychiatric, or any type of system disturbance Physical stat'us 2-mild to moderate systemic disturbance or disease Physical status 3-severe systemic disturbance or disease Physical status &life-threatening severe systemic disorders Physical status 5-moribund patient with little chance of survival The Phase I1 assessment (Fig 2) is initiated when results of Phase I are inconclusive in predicting respiratory depression. Phase I1 measures tidal volume, minute volume, vital capacity, negative inspiratory force, and respiratory rate. Respiratory rate is probably most important because the volume of air is independent of the respiration rate, and the two together provide proper ventilation.s Tidal volume is the amount of air expired in one minute. Vital capacity is the greatest amount or volume of air that can be expired. Negative inspiratory force is a measure of the negative force required during normal ventilation to suck air into the alveolar ducts and sacs. A Wright respirometer and pressure manometer are used to make these assessments. The Wright respirometer measures tidal volume and minute volume accurately, and measures vital capacity within 10%. Both instruments are light and compact and can be attached to a mask placed over the patient's face or to the endotracheal tube. The Phase I11 assessment (Fig 3) is used only if there is question of hypoventilation and there is time for a blood gas analysis. Usually, blood gases are drawn after the initial problem has been treated and used to determine if the treatment is adequate. This assessment is performed by drawing an arterial blood sample and analyzing the blood gases to determine oxygen, POz, PC02, pH, and bicarbonate. This provides definite proof of respiratory 282
acidosis caused by hypoventilation as a result of narcotic anesthesia. Interventions. Treatment of hypoventilation depends on variables such as the patient's health, the amount of narcotic anesthesia given, the type of surgery, and the amount of muscle relaxants used. The Phase I assessment determines nursing actions. Each area is given a value of 0 to 2 points. The patient with a score from 16 to 20 is at minimal risk for hypoventilation. He requires only a face tent, high humidity oxygen, and a stirup regimen to stimulate deep breathing, coughing, and turning. All patients who receive general anesthesia should receive high humidity oxygen. The percentage of oxygen delivered depends on the institution and anesthesiologist and is usually between 40% and 60% with a flow of 6 L to 10 L. Usually, the higher the oxygen percentage, the lower the liter flow. Patients with chronic obstructive pulmonary disease usually require a lower percentage of oxygen because this stimulates them t o breathe. The patient with a score from 12 to 16 points should be examined for the need for ventilatory assistance. The nurse should then proceed to the Phase I1 as-
Treatment depends on a number of variables. sessment to check respiratory status. Patients who score between 12 and 16 need more frequent observation and stir-up regimens to prevent hypoventilation. The nurse should examine the anesthesia record to determine the last dose
AORN Journal, August 1983, Vol38, No 2
Fig 3
Assessment tool for hypoventilation from narcotic anesthesia in the RR Phase Ill Patient’s name
~
~~
~.
The arterial blood gas is a reliable way of diagnosing respiratory acidosis. Find the description that best fits the patient and enter the number of points under the time of assessment. Check the interpretation to see if further assessment is needed at this time. If assessments must still be made after 120 minutes, write the time at the top of the column.
If values do not correlate with those listed, especially the PCOZ,POn, and pH, the problem is not hypoventilationfrom narcotic anesthesia. It is a separate problem that requires diagnosis and treatment.
PH PCO2 PO2 HCOS Base excess
10 points 7.35 to 7.45 34 to 45 mm Hg 80 to 100 mm Hg 24? 1 mEq/L -1 to -2
Score Time of assessment Admission 30 60 90 120
8 points 7.30 to 7.35 45 to 55 mm Hg 60 to 80 mm Hg 2 4 t 3 mEq/L -2 to -5
6 points
< 7.30 > 55 mm Hg <60 mm Hg 2 4 t 6 mEq/L -5 to -7
Discharge
Interpretation of score 10 points: continue present therapy. 8 points: patient requires some increase in ventilation. 6 points: patient needs immediate ventilation.
of naloxone and narcotics. Some patients who receive naloxone before coming to the recovery room score 16 to 20 points on admission, but 10 to 30 minutes later, their score decreases to 12 to 16 points or lower because the naloxone does not last as long as the narcotic. Patients who score less than 12 points on the Phase I assessment are at high risk for hypoventilation. The nurse should then proceed to Phase I1 quickly and monitor the patient closely because this patient may need to be intubated and, if necessary, put on a T-piece or 284
ventilator. The nurse should then determine if the patient has received any naloxone in the operating room and when. Another dose may be needed. If no naloxone was administered, it can now be given to correct the problem of hypoventilation. However, if the patient has received excessive doses of naloxone, he may require ventilation, and if not intubated, the patient should be reintubated. As the naloxone wears off, some patients with respiratory depression may be given physostigmine salicylate (An-
AORN Journal, August 1983, Vol38, N o 2
tilerium). This drug is a nonspecific anticholinesterase that stimulates central and peripheral cholinergic receptor^.^ Physostigmine is used for patients who are agitated during emergence from anesthesia or who are unresponsive to naloxone. The Phase I1 assessment gives more reliable information on the patient's ventilation. If the patient scores between 8 and 10 points, his respiratory status is good. The stir-up regimen and oxygen are continued, and naloxone usage and need are evaluated. If the patient scores between 6 and 8 points, the nurse should watch the patient closely and, if possible, obtain an arterial blood gas sample. If the patient is intubated, the stir-up regimen should be continued. If the patient is not intubated, the nurse should prepare for possible administration of naloxone or reintubation. If additional doses of naloxone are given, the patient is watched for respiratory depression because the effects of naloxone may wear off before the narcotic. If possible, a blood gas analysis is obtained to determine the degree of hypoventilation and respiratory acidosis. If the patient scores below 6, the nurse should assist ventilation, prepare to reintubate, and have a ventilator available. A blood gas analysis should be obtained as soon as possible. In the Phase I11 assessment, if the patient scores 10 points, therapy continues as prescribed. If the patient is intubated and on the ventilator, he may progress to use of a T-piece, depending on the degree of wakefulness. This patient must be watched carefully for potential respiratory depression. If the patient scores only 8 points, more rigorous treatment is initiated. Naloxone is given or ventilation is assisted, or both. If the patient scores less than 6 points, immediately place the patient on ventilatory assistance. A score of 6 or less means the patient is hypoventilating.
This patient requires rigorous treatment to increase ventilation. He has severe respiratory acidosis and respiratory depression. Summary. This assessment tool assists the recovery room nurse to determine respiratory depression and hypoventilation. In Phase I, the nurse performs a general assessment and assigns values to them to describe the patient's respiratory status. Phase I1 assessments measure the patient's actual ventilations, determining that oxygen is getting to the lungs. In the Phase I11 assessment, the amount of oxygen entering the blood and going to the tissues is measured. This assessment tool can help the recovery room nurse predict, prevent, and treat hypoventilation or respiratory depression resulting from narcotic anesthesia. 0 Notes 1. J J Downes, R A Kemp, C J Lambertsen, "The magnitude and duration of respiratory depression due to fentanyl and meperidine in man," Journal of Pharmacology and ExperimentalTherapeutics 158 (1967) 416-420. 2. M H Harper et al, "The magnitude and duration of respiratory depression produced by fentanyl and fentanyl plus droperidol in man," Journal of Pharmacology and Experimental Therapeutics 199 (1976) 464-468. 3. J S Finch, T J deKornfeld, "Clinical investigations of the analgesic potency and respiratory depressant activity of fentanyl, a new narcotic analgesic," Journal of Clinical Pharmacology 7 (1967) 46-51. 4. L S Goodman, A Gilman, The Pharmacological Basic of Therapeutics, 5th ed (New York: Macmillan, 1975). 5. J A Aldrete, D Kroulike, "A postanesthesia recovery score," Anesthesia and Analgesiaxurrent Researches (November-December 1970) 924-933. 6. H C Churchill-Davidson, ed., Practice of Anaesthesia, 4th ed (Philadelphia:W B Saunders Co, 1978) 68. 7. V I Collins, Principles of Anesthesiology, 2nd ed (Philadelphia: Lea 8 Febinger, 1978). 8. R D Dripps, J E Eckenhoff, L D Vandem, Introduction to Anesthesia: The Principles of Safe Practice, 6th ed (Philadelphia: W B Saunders, 1982) 145-159.
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