Recovery from Anesthesia (Anesthesia Text)


Residual Paralysis in the PACU[edit]

Berg Study: TOF < 0.7 in Pancuronium[edit]

Berg et al. examined 691 patients who received pancuronium, atracurium, or vecuronium during abdominal, gynaecological, or orthopaedic surgery. Postoperatively, the TOF was measured mechanomyographically. The incidence of residual block (TOF < 0.7), was significantly higher in the pancuronium group (59/226, 26%) than in the atracurium/vecuronium groups (24/450, 5.3%). In the pancuronium group, significantly more patients with residual block developed post-operative pulmonary complications (10/59, 16.9%) as compared to patients without residual block (8/167, 4.8%), however this relationship did not hold for the atracurium/vecuronium groups (4.2% vs. 5.4%). Multiple regression analysis indicated that abdominal surgery, age, long-lasting surgery, and a TOF ratio < 0.7 following the use of pancuronium were potential risk factors for the development of POPC.

Murphy: TOF for Critical Respiratory Events[edit]

Murphy et al. collected data over a 1-year period in which PACU nurses identified patients with evidence of a critical respiratory event during the first 15 minutes of PACU admission, after which TOF was quantified using acceleromyography. TOF data were also collected in a control group matched by age, sex, and surgical procedure. A total of 61 of 7459 patients developed a CRE after a general anesthetic (42 were matched with controls for statistical analysis – why not all of them?). The most common CREs among matched cases were severe hypoxemia (52.4%) and upper airway obstruction (35.7%, what about the unmatched cases?). Mean (±sd) TOF ratios were 0.62 (±0.20) in the CRE cases, with 73.8% of the CRE cases having TOF ratios <0.70. In contrast, TOF values in the controls were 0.98 (p < 0.0001).

Debaene Study: Recovery from Single Intubating Dose[edit]

Debaene et al. conducted a prospective trial of 526 patients receiving a single intubating dose of intermediate acting non-depolarizing NMBDs and no reversal. They found that even after 120 minutes, > 30% had a TOF < 0.9, and ~ 10% had a TOF < 0.7 as measured with the TOF Watch acceleromyograph. Importantly, they also found that the sensitivity of the qualitative TOF was only 11% for a TOF < 0.9 (and 27% for a TOF < 0.7). Surprisingly, the sensitivity of the head lift was 11% and 19%, respectively.

Summary of Data[edit]

TOF of 0.7 is a reasonable cutoff for patients who have received pancuronium, as there is evidence that these patients have a significantly increased risk of complications – these data do not hold for vecuronium patients. Murphy’s study showed that the average TOF for patients who had a critical respiratory event was 0.72, based on TOF accelerometry (i.e., quantitative measurements). Debaene’s data establish the insensitivity of both the head lift and the qualitative TOF to detect residual paralysis; however, any conclusions on the decision to reverse must be based on complication rate data.


Respiratory Complications[edit]

Rose et al. prospectively collected and analyzed data on 24,157 PACU admission, and found that critical respiratory events (RR < 8, paCO2 > 50 mm Hg, or stridor or laryngospasm requiring intervention) were related to opiate premedication (OR 1.8), preoperative sedation (OR 2.0), fentanyl > 2 ucg/kg/hr as the sole opioid (OR 1.9), fentanyl combined with morphine (OR 1.6), atracurium at > 0.25 mg/kg/hr (OR 2.2), or thiopental induction as compared to propofol (OR 2.5).