Quid novi in the eldery patient’s anesthesia

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.

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.

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.

Table 4 Exclusion Criteria.

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).

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.

• Instrumental response with Bispectral Index (Table 789)

Table 7 Average values of clinical and instrumental group P.

Table 8 Average values of clinical and instrumental group M.

Table 9 Propofol, Midazolam, Remifentanil during MAC.

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.