Effects of anaesthesia on ventilation/perfusion matching:

Effectiveness of postural lung recruitment on postoperative atelectasis assessed by lung ultrasound in children undergoing lateral thoracotomy cardiac surgery with cardiopulmonary bypass

OBJECTIVES

To assess the effects of postural lung recruitment maneuvers on the postoperative atelectasis assessed by lung ultrasound (LUS) compared with supine position recruitment maneuvers in children undergoing right lateral thoracotomy cardiac surgery with cardiopulmonary bypass.

METHODS

In this randomized and controlled trial, 84 patients aged 3 years or younger, scheduled for right lateral thoracotomy cardiac surgery with cardiopulmonary bypass (CPB) were randomly allocated to postural lung recruitment group or control group. The first LUS exam was performed immediately upon completion of the cardiac surgery (T1), and a repeat ultrasound exam started 1 min after lung recruitment maneuvers (T2). The primary outcome was the incidence of significant atelectasis at T2.

RESULTS

The incidence of significant atelectasis at T2 in the postural lung recruitment maneuver group was lower compared with that in the control group (30.2% vs. 58.1%; odds ratio: 0.31; 95% confidence interval: 0.13-0.76; p = .009). The LUS scores for consolidations and B-lines of the left lung were higher than those of the right lung in both groups at T1. More significant reduction of the left LUS scores and sizes of atelectatic areas were found in the postural lung recruitment group than those in the control group.

CONCLUSIONS

Postoperative postural recruitment maneuver was more effective to improve reaeration of lung than supine position recruitment maneuver in children undergoing right lateral thoracotomy cardiac surgery with CPB.

Post-extubation continuous positive airway pressure improves oxygenation after pediatric laparoscopic surgery: A randomized controlled trial

BACKGROUND

Effects of intraoperative recruitment maneuvers (RMs) on oxygenation and pulmonary compliance are lost during recovery if high inspired oxygen and airway suctioning are used. We investigated the effect of post-extubation noninvasive CPAP mask application on the alveolar arterial oxygen difference [(A-a) DO₂ ] after pediatric laparoscopic surgery.

METHODS

Sixty patients (1-6 years) were randomly allocated to three groups of 20 patients, to receive zero end-expiratory pressure (ZEEP group), RM with decremental PEEP titration only (RM group), or followed with post-extubation CPAP for 5 minutes (RM-CPAP group). Primary outcome was [(A-a) DO₂ ] at 1 hour postoperatively. Secondary outcomes were respiratory mechanics, arterial blood gas analysis, hemodynamics, and adverse events.

RESULTS

At 1 hour postoperatively, mean [(A-a) DO₂ ] (mm Hg) was lower in the RM-CPAP group (41.5 ± 13.2, [95% CI 37.6-45.8]) compared to (80.2 ± 13.7 [72.6-87.5], P < 0.0001] and (59.2 ± 14.6, [54.8-62.6], P < 0.001) in the ZEEP and RM groups. The mean PaO₂ (mm Hg) at 1 hour postoperatively was higher in the RM-CPAP group (156.2 ± 18.3 [95% CI 147.6-164.7]) compared with the ZEEP (95.9 ± 15.9 [88.5-103.3], P < 0.0001) and RM groups (129.1 ± 15.9 [121.6-136.5], P < 0.0001). At 12 hours postoperatively, mean [(A-a) DO₂ ] and PaO₂ were (9.6 ± 2.1 [8.4-10.8]) and (91.9 ± 9.4 [87.5-96.3]) in the RM-CPAP group compared to (25.8 ± 5.5 [23.6-27.6]) and (69.9 ± 5.5 [67.4-72.5], P < 0.0001) in the ZEEP group and (34.3 ± 13.2, [28.4-40.2], P < 0.0001) and (74.03 ± 9.8 [69.5-78.6], P < 0.0001) in the RM group. No significant differences of perioperative adverse effects were found between groups.

CONCLUSIONS

An RM done after pneumoperitoneum inflation followed by decremental PEEP titration improved oxygenation at 1 hour postoperatively. The addition of an early post-extubation noninvasive CPAP mask ventilation improved oxygenation at 12 hours postoperatively.

Recruitment manoeuvres in anaesthesia: How many more excuses are there not to use them?

Pulmonary recruitment manoeuvres (RM) are intended to reopen collapsed lung areas. RMs are present in nature as a physiological mechanism to get a newborn to open their lungs for the first time at birth, and we also use them, in our usual anaesthesiological clinical practice, after induction or during general anaesthesia when a patient is desaturated. However, there is much confusion in clinical practice regarding their safety, the best way to perform them, when to do them, in which patients they are indicated, and in those where they are totally contraindicated. There are important differences between RM in the patient with adult respiratory distress syndrome, and in a healthy patient during general anaesthesia. Our intention is to review, from a clinical and practical point of view, the use of RM, specifically in anaesthesia.

Low-positive pressure ventilation improves non-hypoxaemic apnoea tolerance during ear, nose and throat pan-endoscopy: A randomised controlled trial

BACKGROUND

It has been suggested that oxygenation using pressure support ventilation (PSV) before general anaesthesia can reduce the duration of non-hypoxaemic apnoea.

OBJECTIVE

The objective was to determine whether or not pre-oxygenation with PSV increases the duration of non-hypoxaemic apnoea in non-obese patients during pan-endoscopy.

DESIGN

A randomised, controlled trial.

SETTING

Amiens University Hospital, France.

PATIENTS

Fifty patients scheduled for ENT pan-endoscopy with a BMI lower than 35  kg  m(-2).

INTERVENTION

Patients scheduled for pan-endoscopy were enrolled to receive either 100% oxygen at neutral pressure (the control group) or 100% oxygen with positive-pressure ventilation (a positive inspiratory pressure of 4  cmH2O and a positive end-expiratory pressure of 4  cmH2O; the PSV group) during spontaneous ventilation with a face mask. The goal of pre-oxygenation was to obtain an end-tidal oxygen concentration of more than 90% prior to induction of anaesthesia.

MAIN OUTCOME MEASURES

The primary efficacy criterion was the duration of non-hypoxaemic apnoea (i.e. before the peripheral capillary oxygen saturation fell to 90%). Secondary outcomes were duration of pre-oxygenation, pre-oxygenation failure and tolerance.

RESULTS

The mean (interquartile range) duration of non-hypoxaemic apnoea was longer in the PSV group [598 (447 to 717) s] than in the control group [310 (217 to 451) s] (P < 0.001). Oxygenation time was shorter in the PSV group [190 (159 to 225) s] than in the control group [245 (151 to 435) s] (P = 0.037). Pre-oxygenation was unsuccessful (i.e. end-tidal oxygen concentration was < 90%) in 20% of the patients in the control group but none in the PSV group. The intergroup difference in the duration of pan-endoscopy was not significant. Tolerance was good or very good in all patients.

CONCLUSION

Our results show that pre-oxygenation with PSV is associated with a longer duration of non-hypoxaemic apnoea and a lower frequency of manual reventilation during ENT pan-endoscopy. CLINICALTRIALS.

GOV REGISTRATION NUMBER

NCT02167334.

Pulmonary effects of expiratory-assisted small-lumen ventilation during upper airway obstruction in pigs

Novel devices for small-lumen ventilation may enable effective inspiration and expiratory ventilation assistance despite airway obstruction. In this study, we investigated a porcine model of complete upper airway obstruction. After ethical approval, we randomly assigned 13 anaesthetised pigs either to small-lumen ventilation following airway obstruction (n = 8) for 30 min, or to volume-controlled ventilation (sham setting, n = 5). Small-lumen ventilation enabled adequate gas exchange over 30 min. One animal died as a result of a tension pneumothorax in this setting. Redistribution of ventilation from dorsal to central compartments and significant impairment of the distribution of ventilation/perfusion occurred. Histopathology demonstrated considerable lung injury, predominantly through differences in the dorsal dependent lung regions. Small-lumen ventilation maintained adequate gas exchange in a porcine airway obstruction model. The use of this technique for 30 min by inexperienced clinicians was associated with considerable end-expiratory collapse leading to lung injury, and may also carry the risk of severe injury.