[Targeted temperature management in critical care : current 2011 recommendations]

Establishment of a prospective cohort of mechanically ventilated patients in five intensive care units in Lima, Peru: protocol and organisational characteristics of participating centres

INTRODUCTION

Mechanical ventilation is a cornerstone in the management of critically ill patients worldwide; however, less is known about the clinical management of mechanically ventilated patients in low and middle income countries where limitation of resources including equipment, staff and access to medical information may play an important role in defining patient-centred outcomes. We present the design of a prospective, longitudinal study of mechanically ventilated patients in Peru that aims to describe a large cohort of mechanically ventilated patients and identify practices that, if modified, could result in improved patient-centred outcomes and lower costs.

METHODS AND ANALYSIS

Five Peruvian intensive care units (ICUs) and the Medical ICU at the Johns Hopkins Hospital were selected for this study. Eligible patients were those who underwent at least 24 h of invasive mechanical ventilation within the first 48 h of admission into the ICU. Information on ventilator settings, clinical management and treatment were collected daily for up to 28 days or until the patient was discharged from the unit. Vital status was assessed at 90 days post enrolment. A subset of participants who survived until hospital discharge were asked to participate in an ancillary study to assess vital status, and physical and mental health at 6, 12, 24 and 60 months after hospitalisation, Primary outcomes include 90-day mortality, time on mechanical ventilation, hospital and ICU lengths of stay, and prevalence of acute respiratory distress syndrome. In subsequent analyses, we aim to identify interventions and standardised care strategies that can be tailored to resource-limited settings and that result in improved patient-centred outcomes and lower costs.

ETHICS AND DISSEMINATION

We obtained ethics approval from each of the four participating hospitals in Lima, Peru, and at the Johns Hopkins School of Medicine, Baltimore, USA. Results will be disseminated as several separate publications in different international journals.

Optimal protective hypothermia in arrested mammalian hearts

Many therapeutic hypothermia recommendations have been reported, but the information supporting them is sparse, and reveals a need for the data of target therapeutic hypothermia (TTH) from well-controlled experiments. The core temperature ≤35°C is considered as hypothermia, and 29°C is a cooling injury threshold in pig heart in vivo. Thus, an optimal protective hypothermia (OPH) should be in the range 29-35°C. This study was conducted with a pig cardiopulmonary bypass preparation to decrease the core temperature to 29-35°C range at 20 minutes before and 60 minutes during heart arrest. The left ventricular (LV) developed pressure, maximum of the first derivative of LV (dP/dtmax), cardiac power, heart rate, cardiac output, and myocardial velocity (Vmax) were recorded continuously via an LV pressure catheter and an aortic flow probe. At 20 minutes of off-pump during reperfusion after 60 minutes arrest, 17 hypothermic hearts showed that the recovery of Vmax and dP/dtmax established sigmoid curves that consisted of two plateaus: a good recovery plateau at 29-30.5°C, the function recovered to baseline level (BL) (Vmax=118.4%±3.9% of BL, LV dP/dtmax=120.7%±3.1% of BL, n=6); another poor recovery plateau at 34-35°C (Vmax=60.2%±2.8% of BL, LV dP/dtmax=28.0%±5.9% of BL, p<0.05, n=6; ), which are similar to the four normothermia arrest (37°C) hearts (Vmax=55.9%±4.8% of BL, LV dP/dtmax=24.5%±2.1% of BL, n=4). The 32-32.5°C arrest hearts showed moderate recovery (n=5). A point of inflection (around 30.5-31°C) existed at the edge of a good recovery plateau followed by a steep slope. The point presented an OPH that should be the TTH. The results are concordant with data in the mammalian hearts, suggesting that the TTH should be initiated to cool core temperature at 31°C.