The effects of dexmedetomidine on pulmonary artery pressure in experiment

Effects of dexmedetomidine on dynamic lung compliance in general anesthesia with desflurane: A randomized controlled study

Objective

The aim of this study was to evaluate the effect of dexmedetomidine on lung compliance in patients under general anesthesia with desflurane.

Methods

This prospective, randomized, double-blind, controlled trial included 51 patients who received general anesthesia undergoing lower limb fracture surgery. Participants were assigned to either the experimental (loading dose of 0.25 μg/kg dexmedetomidine over 10 min, followed by a maintenance dose of 0.3 μg/kg/h until the end of the surgery) or control (0.9% saline) group. Anesthesia was maintained with desflurane, analgesics and muscle relaxants. The two groups were compared for hemodynamic parameters, dynamic lung compliance, oxygenation index, and postoperative complications.

Results

While dynamic lung compliance showed no significant difference between the two groups at T1 (P = 0.321), it was significantly higher in the experimental group at all other time points (all P < 0.001). In the control group, Cdyn at T4, T5, T6, and T7 were lower than that at T1 (P = 0.032, 0.043, 0.032 and 0.018, respectively). There were no significant between-group differences in the mean arterial pressure and heart rate. Compared to the control group, the experimental group had a higher oxygenation index at T1 (P < 0.001), T2 (P < 0.001), T3 (P < 0.001), T4 (P = 0.02), and T5 (P = 0.016) and significantly lower peak airway pressure at all time points (all P < 0.001). Both groups had comparable postoperative outcomes.

Conclusions

Dexmedetomidine infusion at a loading dose of 0.25 μg/kg and maintenance dose of 0.3 μg/kg/h improved dynamic lung compliance in patients receiving desflurane during general anesthesia.

ONE-LUNG VENTILATION PATIENTS: CLINICAL CONTEXT OF ADMINISTRATION OF DIFFERENT DOSES OF DEXMEDETOMIDINE

Background

Open and endoscopic thoracic surgeries improve surgical exposure by One-lung ventilation (OLV). The aim of this study was to investigate the effects of different doses of dexmedetomidine on inflammatory response, oxidative stress, cerebral tissue oxygen saturation (SctO2) and intrapulmonary shunt in patients undergoing one-lung ventilation (OLV).

Methods

Seventy-five patients undergoing open pulmonary lobectomy in our hospital from January 2016 to December 2017 were enrolled and randomly divided into high-dose dexmedetomidine group (group D1, 1 mg/kg, n=25), low-dose dexmedetomidine group (group D2, 0.5 mg/kg, n=25) and control group (group C, n=25). Then, arterial blood and internal jugular venous blood were taken before anesthesia induction (T0) and at 15 min after twolung ventilation (T1) and 5 min (T2) and 30 min (T3) after OLV for later use. Next, the changes in hemodynamic parameters [mean arterial pressure (MAP), heart rate (HR) and pulse oxygen saturation (SpO2)] of patients were observed in each group. Enzyme-linked immunosorbent assay (ELISA) was carried out to detect serum inflammatory factors such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) and oxidative stress indicators [superoxide dismutase (SOD) and malondialdehyde (MDA)]. The changes in SctO2, arterial partial pressure of oxygen (PaO2) and intrapulmonary shunt Qs/Qt (a measurement of pulmonary shunt: right-to-left shunt fraction) were observed. Additionally, the changes in lung function indicators like lung dynamic compliance (Cdyn) and airway peak pressure (P_peak) were determined.

Results

There were no statistically significant differences in the MAP, HR and SpO2 among three groups at each observation time point (P>0.05). At T2 and T3, the levels of serum IL-6, TNF-α and IL-8 were obviously decreased in group D1 and D2 compared with those in group C (P<0.05), and the decreases in group D1 were overtly larger than those in group D2, and the decreases at T3 were markedly greater than those at T2 (P<0.05). In comparison with group C, group D1 and D2 had notably reduced levels of serum reactive oxygen species (ROS) and MDA (P<0.05) and remarkably increased SOD content (P<0.05) at T2 and T3, and the effects were markedly better in group D1 than those in group D2. Besides, they were significantly superior at T3 to those at T2 (P<0.05). The SctO2 in group D1 and D2 was evidently lowered at T2 and T3 compared with that at T0, and the decrease in group D1 was distinctly smaller than that in group D2 (P<0.05). The Qs/Qt was significantly lower in group D1 and D2 than that in group C at T2 and T3 (P<0.05), while the PaO2 content was notably raised (P<0.05), and the decrease and increase were significantly larger in group D1 than those in group D2, and they were obviously greater at T3 to those at T2 (P<0.05). At T0 and T1, no significant differences were detected in the Cdyn, Pplat and Ppeak among three groups. At T2 and T3, the Cdyn was significantly elevated, while the Pplat and Ppeak overtly declined (P<0.05), and group D1 had greater changes in comparison with group D2, and the changes were obviously more evident at T3 to those at T2 (P<0.05).

Conclusions

Dexmedetomidine effectively ameliorates inflammatory response and oxidative stress, lowers oxygenation, Qs/Qt and the decrease in SctO2 and improves lung function during OLV, with good efficacy.

Evaluation of the effects of dexmedetomidine infusion on oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease

Background

Dexmedetomidine infusion improves oxygenation and lung mechanics in patients with chronic obstructive lung disease; however, its effect in patients with restrictive lung disease has not been thoroughly investigated yet. The aim of this work was to evaluate the effects of dexmedetomidine infusion on oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease.

Methods

Forty-two morbidly obese patients scheduled for bariatric surgery were included in the study. Patients were randomized to receive either dexmedetomidine infusion at a bolus dose of 1mcg/Kg followed by infusion at 1 mcg/Kg/hour for 90 min (Dexmedetomidine group), or normal saline infusion (Control group). Both groups were compared with regard to: oxygenation {P/F ratio: PaO₂/fraction of inspired oxygen (FiO₂)}, lung compliance, dead space, plateau pressure, blood pressure, and heart rate.

Results

Dexmedetomidine group showed significant improvement of the PaO₂/FiO₂ ratio, and higher lung compliance compared to control group by the end of drug infusion. Dexmedetomidine group demonstrated decreased dead space, plateau pressure, blood pressure, and heart rate compared to control group by the end of drug infusion.

Conclusion

A 90-min dexmedetomidine infusion resulted in moderate improvement in oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease.

Trial registration

clinicaltrials.gov: NCT02843698 on 20 July 2016.

Cardiopulmonary Effects of a Partial Intravenous Anesthesia Technique for Laboratory Swine

Various anesthetic protocols are used in laboratory swine, each with specific advantages and disadvantages. Partial intravenous anesthetic techniques (PIVA) help minimize dose-dependent cardiopulmonary effects of inhalant drugs. The aim of this study was to determine the cardiopulmonary effects of a PIVA in laboratory swine. In a prospective, nonrandomized clinical study, 8 healthy juvenile Landrace-White pigs were premedicated with azaperone (0.20 ± 0.20 mg/kg IM), dexmedetomidine (0.02 ± 0.002 mg/kg IM), and alfaxalone (2.0 ± 0.20 mg/kg IM), and anesthesia was induced with intravenous alfaxalone. Anesthesia was maintained by using constant-rate infusion of dexmedetomidine (2 μg/kg/h) and alfaxalone (25 μg/kg/min) in combination with isoflurane. After the fraction of expired isoflurane was adjusted to 1.1% to 1.5%, respiratory rate, heart rate, systemic and pulmonary arterial pressure, central venous pressure, cardiac output, bispectral index, systemic vascular resistance, and arterial and mixed venous blood gases were recorded every 10 min for 60 min. Statistical analysis consisted of repeated-measures one-way ANOVA. Significant decreases occurred in heart rate, pulmonary mean arterial pressure, pulmonary diastolic pressure, partial pressure of arterial oxygen, partial pressure of venous oxygen; significant increases occurred in respiratory rate, minute volume index, diastolic arterial blood pressure, systemic vascular resistance, and arterial pH over time. We consider that the observed statistically significant cardiopulmonary changes were clinically important and that the PIVA protocol provided hemodynamic and respiratory stability for short-term anesthesia of laboratory swine.

Effects of dexmedetomidine on oxygenation and lung mechanics in patients with moderate chronic obstructive pulmonary disease undergoing lung cancer surgery: A randomised double-blinded trial

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a risk factor that increases the incidence of postoperative cardiopulmonary morbidity and mortality after lung resection. Dexmedetomidine, a selective α₂-adrenoreceptor agonist, has been reported previously to attenuate intrapulmonary shunt during one-lung ventilation (OLV) and to alleviate bronchoconstriction.

OBJECTIVE

The objective is to determine whether dexmedetomidine improves oxygenation and lung mechanics in patients with moderate COPD during lung cancer surgery.

DESIGN

A randomised, double-blinded, placebo-controlled study.

SETTING

Single university hospital.

PARTICIPANTS

Fifty patients scheduled for video-assisted thoracoscopic surgery who had moderate COPD. Patients were randomly allocated to a control group or a Dex group (n = 25 each).

INTERVENTIONS

In the Dex group, dexmedetomidine was given as an initial loading dose of 1.0 μg kg⁻¹ over 10 min followed by a maintenance dose of 0.5 μg kg⁻¹ h⁻¹ during OLV while the control group was administered a comparable volume of 0.9% saline. Data were measured at 30 min (DEX-30) and 60 min (DEX-60) after dexmedetomidine or saline administration during OLV.

MAIN OUTCOME MEASURES

The primary outcome was the effect of dexmedetomidine on oxygenation. The secondary outcome was the effect of dexmedetomidine administration on postoperative pulmonary complications.

RESULTS

Patients in the Dex group had a significantly higher PaO₂/FiO₂ ratio (27.9 ± 5.8 vs. 22.5 ± 8.4 and 28.6 ± 5.9 vs. 21.0 ± 9.9 kPa, P < 0.05), significantly lower dead space ventilation (19.2 ± 8.5 vs. 24.1 ± 8.1 and 19.6 ± 6.7 vs. 25.3 ± 7.8%, P < 0.05) and higher dynamic compliance at DEX-30 and DEX-60 (P = 0.0001 and P = 0.0184) compared with the control group. In the Dex group, the PaO₂/FiO₂ ratio in the postoperative period was significantly higher (P = 0.022) and the incidence of ICU admission was lower than in the control group.

CONCLUSION

Dexmedetomidine administration may provide clinically relevant benefits by improving oxygenation and lung mechanics in patients with moderate COPD undergoing lung cancer surgery.

TRIAL REGISTRATION

ClinicalTrial.gov identifier: NCT 02185430.