Intraoperative protective ventilation in patients undergoing major neurosurgical interventions: a randomized clinical trial.

BACKGROUND: Post-operative pulmonary complications (PPC) can develop in up to 13% of patients undergoing neurosurgical procedures and may adversely affect clinical outcome. The use of intraoperative lung protective ventilation (LPV) strategies, usually including the use of a low Vt, low PEEP and low plateau pressure, seem to reduce the risk of PPC and are strongly recommended in almost all surgical procedures. Nonetheless, feasibility of LPV strategies in neurosurgical patients are still debated because the use of low Vt during LPV might result in hypercapnia with detrimental effects on cerebrovascular physiology. Aim of our study was to determine whether LPV strategies would be feasible compared with a control group in adult patients undergoing cranial or spinal surgery. METHODS: This single-centre, pilot randomized clinical trial was conducted at the University Hospital "Maggiore della Carità" (Novara, Italy). Adult patients undergoing major cerebral or spinal neurosurgical interventions with risk index for pulmonary post-operative complications > 2 and not expected to need post-operative intensive care unit (ICU) admission were considered eligible. Patients were randomly assigned to either LPV (Vt = 6 ml/kg of ideal body weight (IBW), respiratory rate initially set at 16 breaths/min, PEEP at 5 cmH2O and application of a recruitment manoeuvre (RM) immediately after intubation and at every disconnection from the ventilator) or control treatment (Vt = 10 ml/kg of IBW, respiratory rate initially set at 6-8 breaths/min, no PEEP and no RM). Primary outcomes of the study were intraoperative adverse events, the level of cerebral tension at dura opening and the intraoperative control of PaCO2. Secondary outcomes were the rate of pulmonary and extrapulmonary complications, the number of unplanned ICU admissions, ICU and hospital lengths of stay and mortality. RESULTS: A total of 60 patients, 30 for each group, were randomized. During brain surgery, the number of episodes of intraoperative hypercapnia and grade of cerebral tension were similar between patients randomized to receive control or LPV strategies. No difference in the rate of intraoperative adverse events was found between groups. The rate of postoperative pulmonary and extrapulmonary complications and major clinical outcomes were similar between groups. CONCLUSIONS: LPV strategies in patients undergoing major neurosurgical intervention are feasible. Larger clinical trials are needed to assess their role in postoperative clinical outcome improvements. TRIAL REGISTRATION: registered on the Australian New Zealand Clinical Trial Registry ( www.anzctr.org.au ), registration number ACTRN12615000707561.

Noninvasive ventilation after early extubation in patients recovering from hypoxemic acute respiratory failure: a single-centre feasibility study.

PURPOSE: The use of noninvasive ventilation (NIV) to facilitate discontinuation of mechanical ventilation in patients with acute hypoxemic respiratory failure (hypoxemic ARF) has never been explored. This pilot study aims to assess the feasibility of early extubation followed by immediate NIV, compared conventional weaning, in patients with resolving hypoxemic ARF. METHODS: Twenty consecutive hypoxemic patients were randomly assigned to receive either conventional weaning or NIV. The changes in arterial blood gases and respiratory rate were compared between the two groups at 1, 12, 24 and 48 h. Differences in the rate of extubation failure, ICU and hospital mortality, number of invasive-ventilation-free-days at day 28, septic complications, number of tracheotomies, days and rates of continuous intravenous sedation, and ICU length of stay were also determined. RESULTS: No patient interrupted the study protocol. Arterial blood gases were similar during invasive mechanical ventilation, 1 h after NIV application following extubation, and after 12, 24 and 48 h. Respiratory rate was higher after 1 h in the NIV group, but no different after 12, 24 and 48 h. The number of invasive-ventilation-free-days at day 28 was 20 ± 8 (min = 0, max = 25) days in the treatment group and 10 ± 9 (min = 0, max = 25) days in the control group (p = 0.014). The rate of extubation failure, ICU and hospital mortality, tracheotomies, septic complications, days and rates of continuous sedation, and ICU length of stay were not significantly different between the two groups. CONCLUSIONS: In a highly experienced centre NIV may be used to facilitate discontinuation of mechanical ventilation in selected patients with resolving hypoxemic ARF.

Influence of lung collapse distribution on the physiologic response to recruitment maneuvers during noninvasive continuous positive airway pressure.

PURPOSE: Noninvasive continuous positive airway pressure (n-CPAP) has been proposed for the treatment of hypoxemic acute respiratory failure (h-ARF). Recruitment maneuvers were shown to improve oxygenation, i.e., the ratio of arterial oxygen tension to inspiratory oxygen fraction (PaO2/FiO2), during either invasive mechanical ventilation, and n-CPAP, with a response depending on the distribution of lung collapse. We hypothesized that, during n-CPAP, early h-ARF patients with bilateral (B(L)) distribution of lung involvement would benefit from recruitment maneuvers more than those with unilateral (U(L)) involvement. METHODS: To perform a recruitment maneuver, once a minute we increased the pressure applied to the airway from 10 cmH2O to 25 cmH2O for 8 s (SIGH). We enrolled 24 patients with h-ARF (12 B(L) and 12 U(L)) who underwent four consecutive trials: (1) 30 min breathing through a Venturi mask (V(MASK)), (2) 1 h n-CPAP (n-CPAP1), (3) 1 h n-CPAP plus SIGH (n-CPAP(SIGH)), and (4) 1 h n-CPAP (n-CPAP2). RESULTS: Compared to V(MASK), n-CPAP at 10 cmH2O delivered via a helmet, increased PaO2/FiO2 and decreased dyspnea in both B(L) and U(L); furthermore, it reduced the respiratory rate and brought PaCO2 up to normal in B(L) only. Compared to n-CPAP, n-CPAP(SIGH) significantly improved PaO2/FiO2 in B(L) (225 ± 88 vs. 308 ± 105, respectively), whereas it produced no further improvement in PaO2/FiO2 in U(L) (232 ± 72 vs. 231 ± 77, respectively). SIGH did not affect hemodynamics in both groups. CONCLUSIONS: Compared to n-CPAP, n-CPAP(SIGH) further improved arterial oxygenation in B(L) patients, whereas it produced no additional benefit in those with U(L).