Quid novi in the eldery patient’s anesthesia

Abstract

Background Today the availability of new local anesthetics and the use of analgesics, allow the modulation of the analgesia, maintaining a state of consciousness. An answer to the needs of patients >75 years undergoing surgery is the technique Monitored Anesthesia Care (MAC), defined “the middle land” (Figure 1). Figure 1 Monitored anestesia care MAC allows: - the modulation of the level of analgesia at different stages of surgery due to the availability of analgesic action, but with rapid onset-time - the additional analgesia using local anesthetics with prolonged effect without the use of noradrenaline, dangerous for elderly patients the consciousness and cooperation of the patient (Table 1). Table 1 MAC. Conscious Sedation ( MAC ) Unconscious Sedation Altered consciousness Unconsciousness Conscious patient Unconscious patient Protective reflexes intact and active Protective reflexes decreased; airway obstruction may occurVentilation: hypoxia, hypercapniaCardiovascular system: , hypotension, hypertension, bradycardia, tachycardia Stable vital signs Unstable vital signs Analgesia may be present; need for regional analgesia / local or systemic Pain controlled centrally; does not require regional analgesia Limited stay in the units of observation Requiring hospitalization or prolonged hospitalization Low risk of complications High risk of complications Infrequent postoperative complications Frequent postoperative complications Patients with psychiatric problems or mental deficiency may be difficult to manage May be needed to manage patients with mental deficiency Materials and methods With this study we tested the efficacy, safety and limitations of the MAC. The design of the study was a prospective, double-blind, parallel-group, with 42 patients randomly selected from 87 patients recruited between those eligible for inclusion in the circuit one-day surgery (Table 2) Table 2 Patients’ criteria of homogeneity. Patients’ criteria of homogeneity same level of gravity ASA II/III NYHA II class same duration of surgery (40 min ± 10 min Two groups were subjected to two different regimes of sedation with propofol and midazolam, pain controlled with remifentanil. - Primary end-point was verifying the level and quality of sedation achieved - Secondary end-point was identifying and quantifying potential adverse effects (Table 3-4) Table 3 Access Criteria. ACCESS CRITERIA Weight 69 ± 6 Kg Informed consent for MAC procedures ASA II/III with stabilized cardio-circulatory impairments and respiratory parameters: pO2 ≤ 70 e pCO2 < 45 mmHg Patients undergoing operations can be managed only with the cooperation of the patient Age > 75 years Table 4 Exclusion Criteria. EXCLUSION CRITERIA Patient desire ASA III impairment of vital organs in acute and evolutionary phase Patients with unexpected rapid intubation Patients with high risk of bleeding Severe neurological disorders Levels of sedation, pain and mental status were assessed using different clinical approaches : - Observational data (Table 5). Table 5 Observer’ s assessment of alertness/sedation scale (oaa/s scale). Answer Verbal expression Facial expression Eyes Ready to the call, normal tone Normal Normal Normal 5 Torpid to the call, normal tone Initial slowdown Medium relaxation Medium relaxation 4 Only for repeat calls with high tone slowdown Marked relaxation Marked ptosis 3 Only if shaken Not understandable words --- --- 2 No answers, even if shaken --- --- --- 1 We proceeded as follows: 1) O2 inhalation (SpO2 > 98 and normocapnia) 2) during surgical manipulation a continuous infusion of remifentanil: 0.03 to 0.06 mg / kg / h was activated Patients were randomly dichotomized into two arms with two different infusion regimens: -group P (45 patients): starter bolus of 0.5 mg / kg propofol (to fill the central compartment) → P infusion of 1-2 mg / kg / h (to offset the rapid deployment) -group M (41 patients): bolus starter from 0.03 to 0.05 mg / kg midazolam (average dose of 2-4 mg) infusion of 1-2 mg / kg / h Every 10 m’ scores are recorded, BIS and OAA / S scale. - objective parameters based on Ramsay Scale (Table 6). Table 6 Ramsay Scale. 1 Patient anxious and agitated or restless, or both 2 Patient co-operative, orientated and tranquil 3 Patient responds to commands only 4 Brisk response to a light glabellar tap or auditory stimulus 5 Sluggish response to a light glabellar tap or auditory stimulus 6 No response to the stimuli mentioned in items 4 and 5 - Instrumental response with Bispectral Index (Table 7 8 9) Table 7 Average values of clinical and instrumental group P. T10m T20m T30m T40m BIS 72 (42-45) 66 (35-88) 70 (55-82) 74 (52-88) OAA/S 4 (1-5) 3-4 (1-5) 3-4(1-5) 4 (1-5) Table 8 Average values of clinical and instrumental group M. T10m T20m T30m T40m BIS 64 (48-86) 58 (35-73) 62 (36-84) 66 (48-83) OAA/S 4 (1-5) 3-4 (1-5) 3-4 (1-5) 4 (1-5) Table 9 Propofol, Midazolam, Remifentanil during MAC. Propofol Midazolam Remifentanil onset of sedation rapid moderate rapid resolution pharmacological effects rapid lenta rapid injection pain yes no no intraoperative and postoperative pain moderate moderate minimum hemodynamic depression moderate minimum minimum respiratory variations mild desaturation (<30%) minimum moderate PONV minimum minimum minimum Conclusions The combination midazolam-remifentanil presented a lower synergistic effect compared with propofol-remifentanil. The first fact documented a mean BIS of 62.5 +3 vs. 64.7 +4 midazolam-remifentanil association and has finally, although sporadic, incidents of desaturation content and never > 30%. The evaluation of the kinetic values of BIS, the interesting fact that emerges concerns the values> 70, which represented a significant predictor in the study to better recovery of consciousness, which has helped the fast-traking ongoing day-surgery.