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
figure 1

Monitored anestesia care

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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.
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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.
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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.
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Table 4 Exclusion Criteria.
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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).
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We proceeded as follows:

  1. 1)

    O2 inhalation (SpO2 > 98 and normocapnia)

  2. 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.
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  • Instrumental response with Bispectral Index (Table 789)

Table 7 Average values of clinical and instrumental group P.
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Table 8 Average values of clinical and instrumental group M.
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Table 9 Propofol, Midazolam, Remifentanil during MAC.
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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.