Functional Capacity

Since the main physiologic stimulus to a perioperative endocrine/metabolic response is surgical stress, clinicians should also seek to determine the patient’s functional capacity (FC).15 FC, expressed in metabolic equivalents (METs), relates to a person’s functional reserve and correlates well with maximum oxygen uptake during treadmill testing. One MET is equal to the basal oxygen requirement (i.e., 3.5 ml of O2 per kg per minute) of a 40–year-old, 70-kg man.

A validated method to determine FC, predicated on a person’s ability to perform a spectrum of common daily activities, is presented in Table 4.18-20 FC is classified as excellent (> 10 METs), good (7 METs to 10 METs), moderate (6 METs to 4 METs), or poor (< 4 METs). The inability to climb two flights of stairs or to run a short distance indicates poor functional capacity (< 4 METs). When FC is low, the risk of a major medical event in susceptible patients is increased.15

Table 4. Estimated Energy Requirement for a Spectrum of Common Daily Activities.18-20

<4 METs
  Can you…
  • Take care of yourself?
  • Eat, get dressed, or use the toilet?
  • Walk indoor around the house?
  • Walk 100 m on level ground at 3 to 5 km per hour
≥4 METs

>10 METs
  Can you…
  • Climb two flights of stairs or walk uphill, or run a short distance?
  • Do heavy work around the house like scrubbing floors or lifting or moving heavy furniture?
  • Participate in strenuous sports like swimming, singles tennis, football, basketball, or skiing?

The hemodynamic effects of infiltration anesthesia with 0.045 mg of epinephrine (4.5 cc of a local anesthetic agent with epinephrine 1:100,000) were found to be less than those produced by ergometric-stress testing at ≥ 4 METs.21 Consequently, patients with FC ≥ 4 METs may safely be administered at least 4.5 cc of a local anesthetic agent with epinephrine 1:100,000 and may not need any further evaluation before proceeding with planned dental treatment.