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Preoxygenation in the Elderly: A Comparison of the Four-MaximalBreath and Three-Minute Techniques Stephen J. Valentine, FFARCS, Robert Marjot, FFARCS, and Christopher R. Monk, VALENTINE SJ, MARJOT R, MONK CR. Preoxygenation in the elderly: a comparison of the four-maximal-breath and three-minute techniques. Anesth Analg 1990;71:51&9.

To compare the effectiveness of two routinely used methods of preoxygenation in protecting against hypoxia in the elderly, the arterial 0, saturation was measured using an oximeter. Twenty-four elderly patients (265 yr) presenting for elective orthopedic surgery were randomly allocated to receive either 3-min or four-maximal-breaths of 100% 0, via a Bain circuit. After preoxygenation, anesthesia was induced, tracheal intubation performed with patients kept apneic, and the endotracheal tube 1tft open to air. The arterial

Preoxygenation is recommended before the induction of anesthesia and muscle paralysis, particularly if there is increased risk of gastric regurgitation or if a difficult intubation is expected. The preoxygenation with 100% oxygen (0,) replaces the nitrogen contained in the functional residual capacity and so prolongs the time before hypoxia occurs after the onset of apnea. Previous studies have compared the different methods of preoxygenation but mainly in younger ASA physical status I and I1 patients (1-5). The question of the relative efficacies of a four-maximal-breath and a 3-min technique has not been addressed in an elderly population, and yet it has important connotations for both routine and emergency geriatric anesthesia where both methods are accepted practice.

Patients and Methods The study was approved by the hospital ethical committee, and written informed consent was obtained from all patients. Twenty-four elderly patients Received from the Sir Humphry Davy Department of Anaesthesia, Bristol Royal Infirmary, Marlborough Street, Bristol, United Kingdom. Accepted for publication July 2, 1990. Address correspondence to Dr. Valentine, Sir Humphry Davy Department of Anaesthesia, Bristol Royal Infirmary, Marlborough Street, Bristol, 852 8HW, United Kingdom. 01990 by the International Anesthesia Research Society

FFARCS

0, saturation was measured before preoxygenation and continually recorded during desaturation. Although attaining similar arterial 0, saturation values after preoxygenation, patients in the four-maximal-breath group had significantly shorter times (P < 0.0001) to all ltwels of desaturation. W e suggest that preoxygenation with 3-min breathing of 100% 0, offers more protection against hypoxia due to prolonged apnea after induction of anesthesia in the elderly than does four maximal breaths of 100% 0,.

Key Words: OXYGEN, DENITROGENATION, preinduction. INDUCTION, ANESTHESIApreoxygenation.

(aged 265 yr) presenting for routine orthopedic surgery were prospectively studied after being randomly allocated to receive either the 3-min or fourmaximal-breath technique of preoxygenation. Patients excluded were those with clinically significant cardiovascular, respiratory, neurologic, or endocrine disease, as were patients with obesity or those in whom difficult intubation could be predicted. During the preoperative assessment, the appropriate method of preoxygenation was explained to each patient. Premedication was with oral tempazepam (0.1-0.2 mg/kg) given 90 min preoperatively. In the anesthetic room the patients were again instructed in the technique of preoxygenation, and intravenous access was secured with a 16-gauge cannula. Monitoring was with a Dinamap (1846SX) automated blood pressure device, electrocardiogram in the CM5 configuration, and a pulse oximeter (Datex Satlite) applied to a thumb. Baseline measurements were recorded with patients breathing air. Patients were pretreated with atropine (10 p g k g ) and vecuronium (10 pglkg) 3 min before induction. Preoxygenation was accomplished with an appropriately sized face mask connected to a Bain circuit that had been flushed with 100%02. The O2flow rate was 10 Wmin in the 3-min group and 35 L/min in the four-maximal-breath group to maintain the filling of the reservoir bag during inspiration and prevent any

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Table 1. Demographic Data and Times to Apnea Age Group

(Y‘)

4 VCJ ( n = 12) 3 rnin” ( n = 12)

74.6 2 6.0 (62-73) 79.2 2 5.9 (7G92)

Height (m)

Weight (kg)

Sex (M/F)

Hb (g/dL)

Time to apnea (s)

1.71 k 0.09 (1.57-1.88)

63.4 k 8.8 (51-74)

913

14.4 2 1.2 (12.6-16.8)

40.4 2 5.0 (3045)

1.65 k 0.07 (1.551.78)

62.8 k 8.1 (53-74)

913

14.3 2 1.3 (11.8-16.7)

39.2 2 9.5 (20-50)

Hb, hemoglobin. Values are mean 2 SD, with range given in parentheses. “Patients receiving the four-vital-capacity-breath method of preoxygenation. ”Patients receiving the 3-min method of preoxygenation

100

.

X

99 98 97 96 2

P

95

U az

94

I-

Figure 1. Times to decrease in saturation from peak Sao, to lowest Sao, levels. 0 , four-maximalbreath group; X, 3-min group.

a

v,

93

5

92

* 0 x

CI

2

91

9

90

a

89

6 be

8a I 0

1

I

I

I

I

I

1

1

2

3

4

5

0

l

PEAK SaO,

rebreathing. Patients in the 3-min group were asked 3 continue to breathe normally after application of the face mask while preoxygenation was performed for 3 min. Patients in the four-breath group were asked to exhale maximally, an effective seal being obtained with the face mask, and then requested to take four maximal breaths. They were then told to breathe normally. Immediately after completing the preoxygenation maneuvers anesthesia was induced with thiopental ( 2 4 mg/kg) and succinylcholine (1.5 mg/kg). The patients were not ventilated until the end of the study. With the onset of anesthesia and muscle paralysis cricoid pressure was applied, and the patients’ trachea intubated under direct vision. After successful intubation was visually confirmed the endotracheal tube was left open to air. If visual confirmation was not possible the patient was excluded from the trial, the airway secured, and the lungs ventilated with 100% 0,. Supplemental doses of thiopental (1 mg/kg) and succinylcholine (0.5 mg/kg) were given every 2 min to maintain anesthesia and muscle paralysis. A continuous recording of the arte~~

a

+

TIME(minuter)

rial 0, saturation (Sao,) was made and the heart rate and blood pressure recorded at 1-min intervals. The study was completed when the Sao, had decreased to 90%, the lungs then being ventilated with 100% O2 until the Sao, was greater than 97%. The demographic data were compared by analysis of variance. Arterial 0, saturation while breathing air, the peak Sao, obtained after preoxygenation, and mean times to the onset of apnea and each desaturation point were compared using the Mann-Whitney U test. P values of less than 0.05 were considered to be statistically significant.

Results The demographic data for the two groups are shown in Table 1. There is no significant difference in age, height, weight, hemoglobin concentration, or time to apnea after induction of anesthesia. The number of men and women was similar in each group, with a similar distribution of smokers and nonsmokers. No

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Table 2. Oxygen Saturation Levels Before and After Preoxygenation and Times to Arterial Desaturation Group

Sao, on air

Peak Sao, on 100%0,

Time to 97% Sao,

Time to 95% Sao,

Time to 93% Sao,

Time to 90% Sao,

4 VC" (n = 12) 3 minb (n = 12)

95.4 2 1.7 (93-97) 95.2 t 2.2 (92-98)

99.8 2 0.5 (99-100) 99.5 2 0.8 (98-100)

147.5 2 82.4 (30-260)" 296.7 f 72.5 (220450)

177.1 2 90.7 (50-31 0)c 315.3 5 69.5 (265-500)

193.7 2 92.1 (70-315)c 382.9 t 74.2 (275-530)

212.1 2 91.8 (80-320)" 405.8 2 75.4 (290-550)

Sao,, arterial oxygen saturation. Values are mean 5 SD, with the range given in parentheses. Time is given in seconds. "Patients receiving the four-vital-capacity-breath method of preoxygenation. 'Patients receiving the 3-min method of preoxygenation.

'P < 0.0001.

significant hemodynamic disturbance occurred in any patient, and all patients were successfully intubated at the first attempt. After completion of the study and hand ventilation with 100% O,, Sao, values in all patients were 97% or greater within 45 s . No patient recalled any events after induction. The saturation results are shown in Table 2 and Figure 1. There was no significant difference between the two groups in Sao, while breathing air, or in the peak Sao, after preoxygenation. Patients in the fourmaximal-breath group had significantly shorter times to desaturation to each Sao, level recorded (P < 0.0001). The times to 90% saturation were 212.1 + 91.8 s in the four-breath group and 405.8 + 75.4 s in the 3-min group. Four patients in the maximal-breath group desaturated to 90% in 2 min or less. The shortest time to this level of desaturation in the 3-min group was 4 min 50 s .

Discussion Various methods of preoxygenation to protect against hypoxemia after induction of anesthesia have been recommended. Previous studies of these techniques have been primarily restricted to fit young adult patients or volunteers (1-5). This study has examined the efficacy of two standard techniques of preoxygenation in an elderly population scheduled for elective surgery. The design of the study ensured airway protection allowing for rapid oxygenation once the saturation had decreased to 90% or if any deterioration in patient condition occurred. By leaving the endotracheal tube open to air and keeping the patient anesthetized and apneic, the 0, reserve was measured by observation of the time required for arterial desaturation to occur after induction of anesthesia. Other investigators have estimated 0, reserve indirectly by measuring arterial O2 tension (Pao,) (2), but factors other than Pao, at completion of preoxygenation may influence 0, reserve (3).

Drummond and Park have shown that age, forced expiratory volume, forced vital capacity, and smoking habits were not related to the rapidity of desaturation after induction of anesthesia, but that obesity was (1). They suggested that three vital capacity breaths of 100% 0, would allow a 3-min period of apnea before the onset of hypoxemia. Without preoxygenation, only 1 min elapsed before significant desaturation occurred. Gold and Muraavchick compared four maximally deep breaths of 100% 0, against air in patients (aged 4CL73 yr), and found Pao, values higher in the preoxygenation group at the time of intubation (2). No comment was made on the effect of age on Pao,. In comparing four maximal breaths with 3 min of preoxygenation in ASA physical status I patients (aged 23-37 yr) Gambee et al. reported that although the Sao, remained above 90% for more than 4 min of apnea in both groups, the latter technique gave longer protection against desaturation (3). Norris and Dewan (5) showed that in the pregnant patient there was no difference in the Pao, in maternal or fetal samples after 3 min or four maximal breaths of preoxygenation. These studies suggest that the four-maximal-breath technique affords adequate protection against inadvertent desaturation. Our investigation was designed to test the efficacyof this technique in geriatric patients presenting for elective orthopedic surgery. There were no demographic differences between the two groups of patients in our study, and times to apnea were the same, implying that the period of breathing 100% 0, was similar in the two groups after induction of anesthesia but before onset of muscle paralysis. Patients in our four-maximal-breath group were told to breathe normally after their last maximal breath, thus avoiding the possibility of active exhalation and loss of the expiratory reserve volume immediately before apnea. The patients assigned to the four-maximal-breath technique had two

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rehearsals of the procedure preoperatively (once in the ward and once in the anesthetic room), and all cooperated to the best of their ability. This rehearsal and cooperation might not be possible with some geriatric patients. We found in our elderly patients similar Sao, values before and after preoxygenation with these two techniques. However, there was a significantly shorter time to all levels of desaturation associated with the four-maximal-breath method. Four patients in this group desaturated to 90% in 2 min or less. The shortest time to 90% saturation in the 3-min group was 4 min 50 s. This difference between our two groups is presumably due to physiologic changes in the respiratory system of the elderly. The aging process is associated with parenchymal changes of the diffuse emphysematous type within the lungs, changes that decrease the alveolar surface area (6,7). The reduced total elastic recoil of the lungs impairs the function of the distal airways with airway closure occurring at the higher lung volumes (8). This encroachment of the closing volume into the tidal volume creates ventilation-perfusion mismatch. The respiratory muscles (diaphragm and intercostal and accessory muscles) act on a less compliant chest wall and are themselves weaker, with decreased strength and speed of contraction (9-11). The vital capacity and inspiratory and expiratory reserve volumes are all diminished. These effects combine to reduce the pulmonary reserve of the elderly in general and appear in particular to render the four-maximalbreath technique less effective in denitrogenating the functional residual capacity. In summary, we found that in this study of elective geriatric patients the four-maximal-breath technique

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gives similar peak Sao, values to the 3-min technique after preoxygenation. However, it does not give reliable protection against desaturation during apnea. We therefore suggest that if preoxygenation is to be performed in the elderly, the 3-min technique should be used.

References 1. Drummond GB, Park GR. Arterial oxygen saturation before intubation of the trachea: an assessment of oxygenation techniques. Br J Anaesth 1984;56:987-92. 2. Gold MI, Muraavchick S. Arterial oxygenation in conscious patients after 3 minutes and after 30 seconds of oxygen breathing. Anesth Analg 1981;60:313-5. 3. Gambee AM, Hertzka RE, Fisher DM. Preoxygenation techniques: comparison of three-minutes and four-breaths. Anesth Analg 1987;66:46&70. 4. Berthoud M, Read DH, Norman J. Preoxygenation-how long? Anaesthesia 1983;38:9&102. 5. Norris MC, Dewan MD. Preoxygenation for cesarian section: a comparison of two techniques. Anaesthesiology 1985;62:827-9. 6. Azcuy A, Anderson AE Jr, Foraker AG. The morphological spectrum of aging and emphysematous lungs. Ann Intern Med 1962;571-17. 7. Pump KK. The aged lung. Chest 1971;60:571-7. 8. Stephen CR, Assaf RAE. Geriatric anaesthesia: principles and practice. London: Butterworth, 1986:69. 9. Mittman C, Edelman NH, Norris AH. Relationship between chest wall and pulmonary compliance and age. J Appl Physiol 1965;20:1211-6. 10. Robinson S. Physical fitness in relation to age. In: Cander L, Moyer JH, eds. Ageing of the lung: perspectives. New York: Grune & Stratton, 1964:287-301. 11. Du Bois AB, Alaela R. Airway resistance and mechanics of breathing in normal subjects 75 to 90 years of age. In: Cander L, Moyer JH, eds. Ageing of the lung: perspectives. New York: Grune & Stratton, 1964:156-62.

Preoxygenation in the elderly: a comparison of the four-maximal-breath and three-minute techniques.

To compare the effectiveness of two routinely used methods of preoxygenation in protecting against hypoxia in the elderly, the arterial O2 saturation ...
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