PERISCOPE study: predicting post-operative pulmonary complications in Europe:

Low tidal volume ventilation for patients undergoing laparoscopic surgery: a secondary analysis of a randomised clinical trial

BACKGROUND

We recently reported the results for a large randomized controlled trial of low tidal volume ventilation (LTVV) versus conventional tidal volume (CTVV) during major surgery when positive end expiratory pressure (PEEP) was equal between groups. We found no difference in postoperative pulmonary complications (PPCs) in patients who received LTVV. However, in the subgroup of patients undergoing laparoscopic surgery, LTVV was associated with a numerically lower rate of PPCs after surgery. We aimed to further assess the relationship between LTVV versus CTVV during laparoscopic surgery.

METHODS

We conducted a post-hoc analysis of this pre-specified subgroup. All patients received volume-controlled ventilation with an applied PEEP of 5 cmH₂O and either LTVV (6 mL/kg predicted body weight [PBW]) or CTVV (10 mL/kg PBW). The primary outcome was the incidence of a composite of PPCs within seven days.

RESULTS

Three hundred twenty-eight patients (27.2%) underwent laparoscopic surgeries, with 158 (48.2%) randomised to LTVV. Fifty two of 157 patients (33.1%) assigned to LTVV and 72 of 169 (42.6%) assigned to conventional tidal volume developed PPCs within 7 days (unadjusted absolute difference, - 9.48 [95% CI, - 19.86 to 1.05]; p = 0.076). After adjusting for pre-specified confounders, the LTVV group had a lower incidence of the primary outcome than patients receiving CTVV (adjusted absolute difference, - 10.36 [95% CI, - 20.52 to - 0.20]; p = 0.046).

CONCLUSION

In this post-hoc analysis of a large, randomised trial of LTVV we found that during laparoscopic surgeries, LTVV was associated with a significantly reduced PPCs compared to CTVV when PEEP was applied equally between both groups.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry no: 12614000790640.

Predictive study of pharmacological reversal for residual neuromuscular blockade and postoperative pulmonary complications: a prospective, observational, cohort study

In recent years, some studies have generated controversy since they conclude that intraoperatively pharmacological reversal of neuromuscular blockade does not contribute to the reduction of postoperative residual neuromuscular blockade or pulmonary complications. Therefore, the main objective of this study was to assess the incidence of residual neuromuscular blockade and postoperative pulmonary complications according to spontaneous or pharmacological neuromuscular reversal. The secondary aim was to present a prognostic model to predict the probability of having postoperative residual neuromuscular blockade depending on a patient's comorbidities and intraoperative neuromuscular blocking agents management. A single-center, prospective, observational cohort study including patients undergoing surgical procedures with general anesthesia was designed. A total of 714 patients were analyzed. Patients were divided into four groups: cisatracurium with spontaneous reversal, cisatracurium with neostigmine antagonism, rocuronium with spontaneous reversal, and rocuronium with sugammadex antagonism. According to our binomial generalized linear model, none of the studied comorbidities was a predisposing factor for an increase in the residual neuromuscular blockade. However, in our study, pharmacological reversal of rocuronium with sugammadex and, particularly, neuromuscular monitoring during surgery were the factors that most effectively reduced the risk of residual neuromuscular blockade as well as early and late postoperative pulmonary complications.

How to optimize critical care resources in surgical patients: intensive care without physical borders

PURPOSE OF REVIEW

Timely identification of surgery patients at risk of postoperative complications is important to improve the care process, including critical care. This review discusses epidemiology and impact of postoperative complications; prediction scores used to identify surgical patients at risk of complications, and the role of critical care in the postoperative management. It also discusses how critical care may change, with respect to admission to the ICU.

RECENT FINDING

Optimization of postoperative outcome, next to preoperative and intraoperative optimization, consists of using risk scores to early identify patients at risk of developing complications. Critical care consultancy should be performed in the ward after surgery, if necessary. ICUs could work at different levels of intensity, but remain preferably multidisciplinary, combining care for surgical and medical patients. ICU admission should still be considered for those patients at very high risk of postoperative complications, and for those receiving complex or emergency interventions.

SUMMARY

To optimize critical care resources for surgery patients at high risk of postoperative complications, the care process should not only include critical care and monitoring in ICUs, but also strict monitoring in the ward. Prediction scores could help to timely identify patients at risk. More intense care (monitoring) outside the ICU could improve outcome. This concept of critical care without borders could be implemented in the near future to optimize the local resources and improve patient safety. Predict more, do less in ICUs, and more in the ward.

Perioperative anaesthetic management of patients with or at risk of acute distress respiratory syndrome undergoing emergency surgery

Patients undergoing emergency surgery may present with the acute respiratory distress syndrome (ARDS) or develop this syndrome postoperatively. The incidence of ARDS in the postoperative period is relatively low, but the impact of ARDS on patient outcomes and healthcare costs is relevant Aakre et.al (Mayo Clin Proc 89:181-9, 2014).The development of ARDS as a postoperative pulmonary complication (PPC) is associated with prolonged hospitalisation, longer duration of mechanical ventilation, increased intensive care unit length of stay and high morbidity and mortality Ball et.al (Curr Opin Crit Care 22:379-85, 2016). In order to mitigate the risk of ARDS after surgery, the anaesthetic management and protective mechanical ventilation strategies play an important role. In particular, a careful integration of general anaesthesia with neuraxial or locoregional techniques might promote faster recovery and reduce opioid consumption. In addition, the use of low tidal volume, minimising plateau pressure and titrating a low-moderate PEEP level based on the patient's need can improve outcome and reduce intraoperative adverse events. Moreover, perioperative management of ARDS patients includes specific anaesthesia and ventilator settings, hemodynamic monitoring, moderately restrictive fluid administration and pain control.The aim of this review is to provide an overview and evidence- and opinion-based recommendations concerning the management of patients at risk of and with ARDS who undergo emergency surgical procedures.

The Carrico index is the parameter that guides the requirement of oxygen in the postoperative period in patients undergoing head and neck surgery under general anaesthesia: a cross-sectional study

BACKGROUND & AIMS

Altered lung function and consequent decrease in oxygenation has been linked to the duration of anaesthesia. This necessitates oxygen monitoring and supplementation in the perioperative period. But, evidence is lacking regarding the parameter that guides best the oxygen supplementation in the postoperative period and the parameter that correlates best with the duration of anaesthesia.

METHODS

Adult patients scheduled for head & neck surgery under general anaesthesia were recruited. Two radial arterial blood samples one at pre-induction and the other at one hour after extubation were obtained. Primary outcome measures were partial pressure of oxygen (PaO2), saturation (SpO2), arterial oxygen content (CaO2) and Carrico index (PaO2/FiO2) and their relation with duration of anaesthesia.

RESULTS

Data from 112 patients showed a hypoxaemia incidence of 11.6%. We observed a drop in the mean CaO2 and haemoglobin concentration but a rise in the mean PaO2 at recovery. The mean PaO2/FiO2 deteriorated by 225.65 ± 72.46 (95% CI 367.66, 83.64, p = 0.000) at recovery and there was a significant correlation (r = 0.2, p = 0.03) between duration of anaesthesia and decrease in PaO2/FiO2 at recovery with a regression coefficient of 0.27 (95% CI 0.02, 0.50).

CONCLUSIONS

The Carrico index was proven to be the best parameter which needs to be monitored perioperatively to detect the alteration in the gaseous exchange in patients undergoing general anaesthesia for head and neck surgery. There is a positive correlation between the decrease in the Carrico index and the duration of anaesthesia especially when it is prolonged beyond 150 minutes.

Perioperative lung protection

Perioperative pulmonary complications are known to be a major cause of morbidity and mortality, and as such, contribute a large burden to the health care system globally. Anesthesiologists have an important role during the perioperative period to identify patients at risk of these complications and intervene in order to reduce them. After describing perioperative pulmonary complications and risk factors for such, this article will address preoperative, intraoperative, and postoperative lung protective strategies to try and reduce the risk of these complications.

Peri-operative pulmonary dysfunction and protection

Pulmonary complications are a major cause of peri-operative morbidity and mortality, but have been researched less thoroughly than cardiac complications. It is important to try and predict which patients are at risk of peri-operative pulmonary complications and to intervene to reduce this risk. Anaesthetists are in a unique position to do this during the whole peri-operative period. Pre-operative training, smoking cessation and lung ventilation with tidal volumes of 6-8 ml.kg(-1) and low positive end-expiratory pressure probably reduce postoperative pulmonary complications.

Monitoring respiration: what the clinician needs to know

A recent large prospective cohort study showed an unexpectedly high in-hospital mortality after major non-cardiac surgery in Europe, as well as a high incidence of postoperative pulmonary complications. The direct effect of postoperative respiratory complications on mortality is still under investigation, for intensive care unit (ICU) and in the perioperative period. Although respiratory monitoring has not been actually proven to affect in-hospital mortality, it plays an important role in patient care, leading to appropriate setting of ventilatory support as well as risk stratification. The aim of this article is to provide an overview of various respiratory monitoring techniques including the role of conventional and most recent methods in the perioperative period and in critically ill patients. The most recent techniques proposed for bedside respiratory monitoring, including lung imaging, are presented and discussed, comparing them to those actually considered as gold standards.

Predicting postoperative pulmonary complications in the general population

PURPOSE OF REVIEW

Postoperative pulmonary complications (PPCs) are common and lead to longer hospital stays and higher mortality. A wide range of patient, anaesthetic and surgical factors have been associated with risk for PPCs. This review discusses our present understanding of PPC risk factors that can be used to plan preoperative risk reduction strategies. The methodological and statistical basis for building risk scores is also described.

RECENT FINDINGS

Studies in specific surgical populations or large patient samples have identified a range of predictors of PPC risk. Factors such as age, types of comorbidity and surgical characteristics have been found to be relevant in most of these studies. Recently, researchers have begun to develop risk scoring systems for a PPC composite outcome or for specific PPCs, especially pneumonia and respiratory failure. Preoperative arterial oxyhaemoglobin saturation is an objective measure that is easy to record and discriminates level of risk for impaired cardiorespiratory function. Preoperative anaemia and recent respiratory infection are factors that have lately been found to confer risk for PPCs.

SUMMARY

PPC risk prediction scales based on large population studies are being developed. New studies to confirm the validity of these scales in different geographic areas will be needed before we can be sure of their generalizability.

Ventilation with low tidal volumes during upper abdominal surgery does not improve postoperative lung function

BACKGROUND

Prolonged postoperative decrease in lung function is common after major upper abdominal surgery. Evidence suggests that ventilation with low tidal volumes may limit the damage during mechanical ventilation. We compared postoperative lung function of patients undergoing upper abdominal surgery, mechanically ventilated with high or low tidal volumes.

METHODS

This was a double-blind, prospective, randomized controlled clinical trial. One hundred and one patients (age ≥ 50 yr, ASA ≥ II, duration of surgery ≥ 3 h) were ventilated with: (i) high [12 ml kg(-1) predicted body weight (PBW)] or (ii) low (6 ml kg(-1) PBW) tidal volumes intraoperatively. The positive end-expiratory pressure was 5 cm H(2)O in both groups and breathing frequency adjusted to normocapnia. Time-weighted averages (TWAs) of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV(1)) until 120 h after operation were compared (P<0.025 considered statistically significant). Secondary outcomes were oxygenation, respiratory and non-respiratory complications, length of stay and mortality.

RESULTS

The mean (sd) values of TWAs of FVC and FEV(1) were similar in both groups: FVC: 6 ml group 1.8 (0.7) litre vs 12 ml group 1.6 (0.5) litre (P=0.12); FEV(1): 6 ml group 1.4 (0.5) litre vs 12 ml group 1.2 (0.4) litre (P=0.15). FVC and FEV(1) at any single time point and secondary outcomes did not differ significantly between groups.

CONCLUSIONS

Prolonged impaired lung function after major abdominal surgery is not ameliorated by low tidal volume ventilation.