Delirium in the Intensive Care Unit: Incidence, Risk Factors, and Impact on Outcome.

BACKGROUND: The incidence and risk factors for delirium vary among studies. OBJECTIVE: We aimed to determine the incidence, risk factors, and impact on outcome of delirium in a medical Intensive Care Unit (ICU) in Tunisia using a prospective observational study. PATIENTS: All consecutive patients admitted to the ICU between May 2012 and April 2013 were included if they were aged more than 18 years and had an ICU stay of more than 24 h. Patients who had a cardiac arrest or have a history of dementia or psychosis were excluded. Patients eligible for the study were evaluated by the medical staff to detect delirium using the CAM-ICU. RESULTS: A total of 206 patients were included, 167 did not present delirium and 39 (19%) were analyzed for delirium. Delirious patients had a significantly longer duration of mechanical ventilation (10 days[6-20] vs. 2 days[0-7]) respectively and length of stay in ICU (21.5 days [10.5-32.5] vs. 8 days [5-13]), with no impact on mortality. Delirium was associated with high incidence of unintentional removal of catheters (39% vs. 9%; P < 0.0001), endotracheal tubes (18% vs. 1%; P < 0.0001), and urinary catheters (28% vs. 2%, P < 0.0001). In multivariable risk regression analysis, age (odds ratio [OR] = 4.1, 95% confidence interval [CI]: 1.39-12.21; P = 0.01), hypertension (OR = 3.3, 95% CI: 1.31-8.13; P = 0.011), COPD (OR = 3.5, 95% CI: 1.47-8.59; P = 0.005), steroids (OR = 2.8, 95% CI: 1.05-7.28; P = 0.038), and sedation (OR = 5.4, 95% CI: 2.08-13.9; P < 0.0001) were independent risk factors for delirium. We did not find a relationship between delirium and mortality. CONCLUSION: Delirium is frequent in the ICU and is associated with poor outcome. Several risk factors for delirium are linked to intensive care environment.

The prevalence of healthcare-associated infection in medical intensive care units in Tunisia. Results of the multi-centre nosorea1 study.

OBJECTIVES: To determine the prevalence of Healthcare-Associated Infection (HAI) in medical Intensive Care Unit (ICU), risk factors for these infections and identify the predominant infecting organisms. METHODS: A 1-day point-prevalence study within all medical ICUs in Tunisia, all patients occupying an ICU bed over a 48-hour period were included. Rates of HAI, resistance patterns of microbiological isolates and potential risk factors for HAI were recorded. RESULTS: One hundred and three patients were collected from 15 Tunisian medical ICUs. HAI prevalence was 25.2% CI 95% [15-35].The most frequent HAIs were hospital acquired pneumonia in 19 cases (59%) and catheter related infection in 5 cases (15%). Independent factors associated with HAI occurrence were SAPSII score ≥ 33 with OR 1.047; CI 95% [1.015-1.077], p=0.003 and recent hospitalization with OR 4.14 CI 95% [1.235-13.889], p=0.021. Non-fermenting pathogens were the most frequent microorganisms reported in ICUs ecology, prior colonization and HAIs of the screened patients. CONCLUSION: HAIs are frequent in medical ICUs in Tunisia, which emphasize the importance of specific measures for surveillance and infection control in critically ill patients. Implementing a national monitoring system of HAI should be a major priority of public health in Tunisia.

Changes in the work of breathing induced by tracheotomy in ventilator-dependent patients.

Tracheotomy is widely performed on ventilator-dependent patients, but its effects on respiratory mechanics have not been studied. We measured the work of breathing (WOB) in eight patients before and after tracheotomy during breathing at three identical levels of pressure support (PS): baseline level (PS-B), PS + 5 cm H2O (PS+5), and PS - 5 cm H2O (PS-5). After the procedure, we also compared the resistive work induced by the patients' endotracheal tubes (ETTs) and by a new tracheotomy cannula in an in vitro bench study. A significant reduction in the WOB was observed after tracheotomy for PS-B (from 0.9 +/- 0.4 to 0.4 +/- 0.2 J/L, p < 0.05), and for PS-5 (1.4 +/- 0.6 to 0.6 +/- 0.3 J/L, p < 0.05), with a near-significant reduction for PS+5 (0.5 +/- 0.5 to 0.2 +/- 0.1 J/L, p = 0.05). A significant reduction was also observed in the pressure-time index of the respiratory muscles (181 +/- 92 to 80 +/- 56 cm H2O. s/min for PS-B, p < 0.05). Resistive and elastic work computed from transpulmonary pressure measurements decreased significantly at PS-B and PS-5. A significant reduction in occlusion pressure and intrinsic positive end-expiratory pressure (PEEP) was also observed for all conditions, with no significant change in breathing pattern. Three patients had ineffective breathing efforts before tracheotomy, and all had improved synchrony with the ventilator after the procedure. In vitro measurements made with ETTs removed from the patients, with new ETTs, and with the tracheotomy cannula showed that the cannula reduced the resistive work induced by the artificial airway. Part of these results was explained by a slight, subtle reduction of the inner diameter of used ETTs. We conclude that tracheotomy can substantially reduce the mechanical workload of ventilator-dependent patients.

Effects of flow triggering on breathing effort during partial ventilatory support.

The effects of flow triggering (FT) as compared with pressure triggering (PT) on breathing effort have been the focus of several studies, and discrepant results have been reported. In the initial part of our study, a lung model was used to quantify triggering effort (airway pressure-time product, PTPaw) for a range of sensitivity settings in nine new-generation ventilators. A ventilator providing both FT and PT was then used to compare these systems during pressure-support (PSV) and volume-targeted assist-control ventilation (ACV) in eight ventilator-dependent patients, using sensitivity settings (2 L/min for FT and -2 cm H2O for PT) that had proven significantly different in the initial bench study. Indexes of effort included the esophageal and transdiaphragmatic pressure-time products and inspiratory work of breathing per minute (PTPes/min, PTPdi/min, and Wi/min, respectively). The experimental study revealed significant differences between ventilators in PTPaw at commonly used settings. In two of three ventilators featuring both systems, PTPaw was significantly lower with FT than PT (p < 0.001). In the clinical study, FT as compared with PT, was associated with reductions in all indexes of breathing effort during PSV: 16 +/- 6% (p < 0.001), 13 +/- 10% (p < 0.01), and 14 +/- 12% (p < 0.05) for PTPdi/min, PTPes/min, and Wi/min, respectively. By contrast, no differences were found when FT was used during ACV. Although FT reduced triggering effort in both modes (p < 0.001), the effects observed during the post-trigger phase differed, and explained the discrepant results between the two modes. We conclude that FT more effectively reduces breathing effort when used in conjunction with a pressure-targeted mode than with a volume-targeted mode, especially when flow delivery is close to or below demand.

Titration of tidal volume and induced hypercapnia in acute respiratory distress syndrome.

Mechanical ventilation may promote overdistension-induced pulmonary lesions in patients with acute respiratory distress syndrome (ARDS). The static pressure-volume (P-V) curve of the respiratory system can be used to determine the lung volume and corresponding static airway pressure at which lung compliance begins to diminish (the upper inflection point, or UIP). This fall in compliance may indicate overdistension of lung units. We prospectively studied 42 patients receiving mechanical ventilation with an FIO2 of 0.5 or more for at least 24 h. According to the Lung Injury Score (LIS), 25 patients were classified as having ARDS (LIS > 2.5), while 17 patients constituted a non-ARDS control group. The P-V curve was obtained every 2 d. Mechanical ventilation initially used standard settings (volume-control mode, a positive end-expiratory pressure [PEEP] adjusted to the lower inflection point on the P-V curve, and a tidal volume [VT] of 10 ml/kg). The end-inspiratory plateau pressure (Pplat) was compared to the UIP, and VT was lowered when the Pplat was above the UIP. In the range of lung volume studied on the P-V curves (up to 1600 ml), a UIP could be shown in only one control patient (at 23 cm H2O). By contrast, a UIP was present on the P-V curve obtained from all patients with ARDS, corresponding to a mean airway pressure of 26 +/- 6 cm H2O, a lung volume of 850 +/- 200 ml above functional residual capacity and 610 +/- 235 ml above PEEP.(ABSTRACT TRUNCATED AT 250 WORDS)