Postoperative respiratory state assessment using the Integrated Pulmonary Index (IPI) and resultant nurse interventions in the post-anesthesia care unit: a randomized controlled trial.

Although postoperative adverse respiratory events, defined by a decrease in respiratory rate (RR) and/or a drop in oxygen saturation (SpO2), occur frequently, many of such events are missed. The purpose of the current study was to assess whether continuous monitoring of the integrated pulmonary index (IPI), a composite index of SpO2, RR, end-tidal PCO2 and heart rate, alters our ability to identify and prevent adverse respiratory events in postoperative patients. Eighty postoperative patients were subjected to continuous respiratory monitoring during the first postoperative night using RR and pulse oximetry and the IPI monitor. Patients were randomized to receive intervention based on standard care (observational) or based on the IPI monitor (interventional). Nurses were asked to respond to adverse respiratory events with an intervention to improve the patient's respiratory condition. There was no difference in the number of patients that experienced at least one adverse respiratory event: 21 and 16 in observational and interventional group, respectively (p = 0.218). Compared to the observational group, the use of the IPI monitor led to an increase in the number of interventions performed by nurses to improve the respiratory status of the patient (average 13 versus 39 interventions, p < 0.001). This difference was associated with a significant reduction of the median number of events per patient (2.5 versus 6, p < 0.05) and a shorter median duration of events (62 s versus 75 s, p < 0.001). The use of the IPI monitor in postoperative patients did not result in a reduction of the number of patients experiencing adverse respiratory events, compared to standard clinical care. However, it did lead to an increased number of nurse interventions and a decreased number and duration of respiratory events in patients that experienced postoperative adverse respiratory events.

Reversal of Partial Neuromuscular Block and the Ventilatory Response to Hypoxia: A Randomized Controlled Trial in Healthy Volunteers.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: The ventilatory response to hypoxia is a critical reflex that is impaired by neuromuscular blocking drugs. However, the degree to which this reflex is restored after reversal of blockade is unknown. WHAT THIS ARTICLE TELLS US THAT IS NEW: Despite full reversal of neuromuscular blockade at the thumb using different drug classes, this hypoxic chemoreflex is not fully restored. BACKGROUND: The ventilatory response to hypoxia is a life-saving chemoreflex originating at the carotid bodies that is impaired by nondepolarizing neuromuscular blocking agents. This study evaluated the effect of three strategies for reversal of a partial neuromuscular block on ventilatory control in 34 healthy male volunteers on the chemoreflex. The hypothesis was that the hypoxic ventilatory response is fully restored following the return to a train-of-four ratio of 1. METHODS: In this single-center, experimental, randomized, controlled trial, ventilatory responses to 5-min hypoxia (oxygen saturation, 80 ± 2%) and ventilation at hyperoxic isohypercapnia (end-tidal carbon dioxide concentration, 55 mmHg) were obtained at baseline, during rocuronium-induced partial neuromuscular block (train-of-four ratio of 0.7 measured at the adductor pollicis muscle by electromyography), and following reversal until the train-of-four ratio reached unity with placebo (n = 12), 1 mg neostigmine/0.5 mg atropine (n = 11), or 2 mg/kg sugammadex (n = 11). RESULTS: This study confirmed that low-dose rocuronium reduced the ventilatory response to hypoxia from 0.55 ± 0.22 (baseline) to 0.31 ± 0.21 l · min · % (train-of-four ratio, 0.7; P < 0.001). Following full reversal as measured at the thumb, there was persistent residual blunting of the hypoxic ventilatory response (0.45 ± 0.16 l · min · %; train-of-four ratio, 1.0; P < 0.001). Treatment effect was not significant (analysis of covariance, P = 0.299) with chemoreflex impairment in 5 (45%) subjects following sugammadex reversal, in 7 subjects (64%) following neostigmine reversal, and in 10 subjects (83%) after spontaneous reversal to a train-of-four ratio of 1. CONCLUSIONS: Despite full reversal of partial neuromuscular block at the thumb, impairment of the peripheral chemoreflex may persist at train-of-four ratios greater than 0.9 following reversal with neostigmine and sugammadex or spontaneous recovery of the neuromuscular block.

Ability of the nociception level, a multiparameter composite of autonomic signals, to detect noxious stimuli during propofol-remifentanil anesthesia.

BACKGROUND: A novel multidimensional index of nociception, the nociception level (NoL) index, derived from the nonlinear composite of heart rate (HR), HR variability, amplitude of the photoplethysmogram, skin conductance, fluctuations in skin conductance, and their time derivatives, was used to assess nociception during anesthesia. METHODS: Seventy-two American Society of Anesthesiologists I to III patients received propofol (target bispectral index, 45) and one of six remifentanil target concentrations in the range of 0 to 5 ng/ml. The NoL, mean arterial pressure (MAP; derived from a beat-to-beat finger cuff measurement), and HR were measured during nonnoxious, moderate noxious (skin incision), and intense noxious (intubation) stimulation. Values are represented as average (95% CI). RESULTS: NoL, HR, and MAP did not change during nonnoxious events. Incision increased HR by 1.3/min (-0.46 to 3.1/min; not significant), MAP by 7.9 mmHg (-1.9 to 13.0 mmHg; not significant), and NoL by 8.0 (0.4 to 16.0; P < 0.001). Intubation increased HR by 7.0/min (1.4 to 12.0/min; P < 0.001), MAP by 13.0 mmHg (3.1 to 20 mmHg; P < 0.001), and NoL by 18.0 (7.8 to 29.0; P < 0.001). The ΔNoL area under the curve (0.95) of the receiver operating characteristic curve was greater compared with ΔHR (0.84, P < 0.001) and ΔMAP (0.78, P < 0.001). Under nonnociceptive conditions, remifentanil had no effect on NoL, in contrast to HR and MAP that showed a dose-dependent decrease. CONCLUSIONS: The NoL is a reliable measure of moderate and intense noxious stimulation and outperforms HR and MAP in differentiating noxious from nonnoxious stimuli. In contrast to HR and MAP, the NoL was not affected by hemodynamic effects of remifentanil.