Amyn Hirani

Dynamic changes in arterial waveform derived variables and fluid responsiveness in mechanically ventilated patients: a systematic review of the literature.

Objectives:A systematic review of the literature to determine the ability of dynamic changes in arterial waveform-derived variables to predict fluid responsiveness and compare these with static indices of fluid responsiveness. The assessment of a patients intravascular volume is one of the most difficult tasks in critical care medicine. Conventional static hemodynamic variables have proven unreliable as predictors of volume responsiveness. Dynamic changes in systolic pressure, pulse pressure, and stroke volume in patients undergoing mechanical ventilation have emerged as useful techniques to assess volume responsiveness. Data Sources:MEDLINE, EMBASE, Cochrane Register of Controlled Trials and citation review of relevant primary and review articles. Study Selection:Clinical studies that evaluated the association between stroke volume variation, pulse pressure variation, and/or stroke volume variation and the change in stroke volume/cardiac index after a fluid or positive end-expiratory pressure challenge. Data Extraction and Synthesis:Data were abstracted on study design, study size, study setting, patient population, and the correlation coefficient and/or receiver operating characteristic between the baseline systolic pressure variation, stroke volume variation, and/or pulse pressure variation and the change in stroke index/cardiac index after a fluid challenge. When reported, the receiver operating characteristic of the central venous pressure, global end-diastolic volume index, and left ventricular end-diastolic area index were also recorded. Meta-analytic techniques were used to summarize the data. Twenty-nine studies (which enrolled 685 patients) met our inclusion criteria. Overall, 56% of patients responded to a fluid challenge. The pooled correlation coefficients between the baseline pulse pressure variation, stroke volume variation, systolic pressure variation, and the change in stroke/cardiac index were 0.78, 0.72, and 0.72, respectively. The area under the receiver operating characteristic curves were 0.94, 0.84, and 0.86, respectively, compared with 0.55 for the central venous pressure, 0.56 for the global end-diastolic volume index, and 0.64 for the left ventricular end-diastolic area index. The mean threshold values were 12.5 ± 1.6% for the pulse pressure variation and 11.6 ± 1.9% for the stroke volume variation. The sensitivity, specificity, and diagnostic odds ratio were 0.89, 0.88, and 59.86 for the pulse pressure variation and 0.82, 0.86, and 27.34 for the stroke volume variation, respectively. Conclusions:Dynamic changes of arterial waveform-derived variables during mechanical ventilation are highly accurate in predicting volume responsiveness in critically ill patients with an accuracy greater than that of traditional static indices of volume responsiveness. This technique, however, is limited to patients who receive controlled ventilation and who are not breathing spontaneously.

Stress ulcer prophylaxis in the new millennium: a systematic review and meta-analysis.

Background:Recent observational studies suggest that bleeding from stress ulceration is extremely uncommon in intensive care unit patients. Furthermore, the risk of bleeding may not be altered by the use of acid suppressive therapy. Early enteral tube feeding (initiated within 48 hrs of intensive care unit admission) may account for this observation. Stress ulcer prophylaxis may, however, increase the risk of hospital-acquired pneumonia and Clostridia difficile infection. Objective:A systematic review of the literature to determine the benefit and risks of stress ulcer prophylaxis and the moderating effect of enteral nutrition. Data Sources:MEDLINE, Embase, Cochrane Register of Controlled Trials, and citation review of relevant primary and review articles. Study Selection:Randomized, controlled studies that evaluated the association between stress ulcer prophylaxis and gastrointestinal bleeding. We included only those studies that compared a histamine-2 receptor blocker with a placebo. Data Extraction:Data were abstracted on study design, study size, study setting, patient population, the histamine-2 receptor blocker and dosage used, the incidence of clinically significant gastrointestinal bleeding, hospital-acquired pneumonia, mortality, and the use of enteral nutrition. Data Synthesis:Seventeen studies (which enrolled 1836 patients) met the inclusion criteria. Patients received adequate enteral nutrition in three of the studies. Overall, stress ulcer prophylaxis with a histamine-2 receptor blocker reduced the risk of gastrointestinal bleeding (odds ratio 0.47; 95% confidence interval, 0.29-0.76; p < .002; I2 = 44%); however, the treatment effect was noted only in the subgroup of patients who did not receive enteral nutrition. In those patients who were fed enterally, stress ulcer prophylaxis did not alter the risk of gastrointestinal bleeding (odds ratio 1.26; 95% confidence interval, 0.43-3.7). Overall histamine-2 receptor blockers did not increase the risk of hospital-acquired pneumonia (odds ratio 1.53; 95% confidence interval, 0.89-2.61; p = .12; I2 = 41%); however, this complication was increased in the subgroup of patients who were fed enterally (odds ratio 2.81; 95% confidence interval, 1.20-6.56; p = .02; I2 = 0%). Overall, stress ulcer prophylaxis had no effect on hospital mortality (odds ratio 1.03; 95% confidence interval, 0.78-1.37; p = .82). The hospital mortality was, however, higher in those studies (n = 2) in which patients were fed enterally and received a histamine-2 receptor blocker (odds ratio 1.89; 95% confidence interval, 1.04-3.44; p = .04, I2 = 0%). Sensitivity analysis and meta-regression demonstrated no relationship between the treatment effect (risk of gastrointestinal bleeding) and the classification used to define gastrointestinal bleeding, the Jadad quality score nor the year the study was reported. Conclusions:The results of this meta-analysis suggest that, in those patients receiving enteral nutrition, stress ulcer prophylaxis may not be required and, indeed, such therapy may increase the risk of pneumonia and death. However, because no clinical study has prospectively tested the influence of enteral nutrition on the risk of stress ulcer prophylaxis, our findings should be considered exploratory and interpreted with some caution.

Association between time of admission to the ICU and mortality: a systematic review and metaanalysis.

BACKGROUND The organizational and staffing structure of an ICU influences the outcome of critically ill and injured patients. A change in the ICU staffing structure frequently occurs at nighttime and on weekends (off-hours). We postulated that patients who are admitted to an ICU during off hours may be at an increased risk of death. METHODS We performed a systematic review of the literature to assess whether admission to an ICU during off-hours is associated with an increased mortality. We selected studies that evaluated the association between time of admission to the ICU and mortality, with adjustment for severity of disease. We excluded studies that included pediatric and non-ICU patients. Study characteristics extracted included date of publication, study design, country where study was done, study population, time factor (weekend or night shift), severity adjustment tool, and outcome. RESULTS Ten cohort studies met our inclusion criteria; eight of these studies evaluated nighttime admissions, whereas six studies evaluated weekend admissions. The pooled analysis demonstrated that nighttime admission was not associated with an increased mortality (odds ratio [OR], 1.0 [95% CI, 0.87-1.17]; P = .956); however, patients admitted over the weekend had a significant increase in the adjusted risk of death (OR, 1.08 [95% CI, 1.04-1.13]; P < .001). Significant heterogeneity was found in the studies that evaluated nighttime admissions. CONCLUSIONS Whereas patients admitted to an ICU over the weekend appear to be at an increased risk of death, nighttime admissions were not associated with an increased mortality. The lower level of staffing and intensity of care provided by many hospitals over the weekend may account for this finding. The heterogeneity noted between studies evaluating nighttime admissions likely reflects the diverse organizational structure of the hospitals and ICUs where these studies were carried out.

Obstructive Sleep Apnea Syndrome and Postoperative Complications: Clinical Use of the STOP-BANG Questionnaire

OBJECTIVE To determine whether high risk scores on preoperative STOP-BANG (Snoring, Tiredness during daytime, Observed apnea, high blood Pressure, Body mass index, Age, Neck circumference, Gender) questionnaires during preoperative evaluation correlated with a higher rate of complications of obstructive sleep apnea syndrome (OSAS). DESIGN Historical cohort study. SETTING Thomas Jefferson University Hospital, Philadelphia, Pennsylvania. PATIENTS Adult patients undergoing elective surgery at a tertiary care center who were administered the STOP-BANG questionnaire for 3 consecutive days in May 2008. MAIN OUTCOME MEASURES Number and types of complications. RESULTS A total of 135 patients were included in the study, of whom 56 (41.5%) had high risk scores for OSAS. The mean (SD) age of patients was 57.9 (14.4) years; 60 (44.4%) were men. Patients at high risk of OSAS had a higher rate of postoperative complications compared with patients at low risk (19.6% vs 1.3%; P < .001). Age, American Society of Anesthesiologists class of 3 or higher, and obesity were associated with an increased risk of postoperative complications. On multivariate analysis, high risk of OSAS and American Society of Anesthesiologists class 3 or higher were associated with higher odds of complications. CONCLUSION The STOP-BANG questionnaire is useful for preoperative identification of patients at higher than normal risk for surgical complications, probably because it identifies patients with occult OSAS.

Norepinephrine or dopamine for septic shock: systematic review of randomized clinical trials.

Received July 30, 2010, and in revised form September 14, 2010. Accepted for publication September 20, 2010. Background: There is debate as to the vasopressor agent of choice in patients with septic shock. According to current guidelines either dopamine or norepinephrine may be considered as the first-line agent for the management of refractory hypotension of septic shock. Objective: The aim of this systematic review was to evaluate randomized clinical trials which compared norepinephrine versus dopamine in critically ill patients with septic shock or in a population of critically ill patients with shock predominantly secondary to sepsis. Data Sources: MEDLINE, Embase, Scopus, Cochrane Register of Controlled Trials and citation review of relevant primary and review articles. Study Selection: Randomized clinical trials that compared norepinephrine with dopamine in critically ill adults with sepsis and reported the 28-day or in-hospital mortality. Data Extraction: We abstracted data on study design, study setting, patient population, 28-day mortality or in-hospital mortality, rate of arrhythmias, hospital length of stay, and ICU length of stay. Data Synthesis: Six studies met our inclusion criteria. These studies included a total of 2043 participants, with 995 in the norepinephrine and 1048 in the dopamine groups. There were 479 (48%) deaths in the norepinephrine group and 555 (53%) deaths in the dopamine group. There was statistically significant superiority of norepinephrine over dopamine for the outcome of in-hospital or 28-day mortality: pooled RR: 0.91 (95% CI 0.83 to 0.99; P = .028). We also found a statistically significant decrease in the rate of cardiac arrhythmias in the norepinephine group as compared to the dopamine group: pooled RR: 0.43 (95% CI 0.26 to 0.69; P ≤ .001). A subgroup analysis that pooled studies in which all the randomized patients had septic shock demonstrated that norepinephrine improved in-hospital or 28-day mortality; however, the results were no longer statistically significant. Conclusions: The analysis of the pooled studies that included a critically ill population with shock predominantly secondary to sepsis showed superiority of norepinephrine over dopamine for in-hospital or 28-day mortality.

Prevalence of obstructive lung disease in HIV population: A cross sectional study

BACKGROUND Observational studies have suggested an association between HIV infection and emphysema. AIMS The primary aim of this study was to estimate the prevalence of obstructive lung disease in HIV-infected patients seen in an outpatient infectious disease clinic. The secondary aim was to estimate the prevalence of Obstructive Lung Disease (OLD) in smokers and non smokers in this population. METHODS This was a prospective cross-sectional study. Consecutive patients who were seen for routine HIV care underwent spirometry and answered the St. Georges Respiratory Questionnaire (SGRQ). Further, we collected information from the charts on demographics, co-morbidities, CD4 cell count, and HIV viral load (current, baseline, etc). RESULTS This study included 98 HIV-infected patients with mean age of 45 years, (SD: 11) and 84% male. They were seen from November 2008 to May 2009 at Thomas Jefferson University in Philadelphia. According to established criteria, spirometry results were classified as normal in 69% and obstructive in 16.3%. Among those who never smoked, the prevalence of obstructive lung disease on spirometry was 13.6%. The prevalence of obstruction in HIV patients with a history of smoking was 18.5%. Current and ever smokers comprised 21.4% and 55% of the patients respectively. The mean SGRQ total score was 7. The mean SGRQ score in active smokers was 17 and 15 in those subjects with a prior history of smoking. The mean SGRQ score among patients with obstruction in spiromerty was 27.7 in patients with obstruction on spirometry. CONCLUSION This urban population of HIV-infected persons has a relatively high prevalence of obstructive lung disease as assessed by spirometry. Furthermore, the high prevalence of obstructive lung disease in never smokers may suggest a possible association between HIV infection and emphysema. In addition the SGRQ total score was comparatively higher in patients with obstruction on spirometry. Our data suggests that potentially all patients with HIV should be screened a for OLD.

Review of A Large Clinical Series: Is the Band Count Useful in the Diagnosis of Infection? An Accuracy Study in Critically Ill Patients:

Background: The presence of immature neutrophils (bands) in the circulating blood is often used as a clinical indicator of sepsis. Indeed, a band count greater than 10% is one of the American College of Chest Physicians/Society of Critical Care Medicine’s systemic inflammatory response syndrome (SIRS) criteria used to diagnose sepsis. However, the literature regarding the diagnostic accuracy of an elevated band count for the diagnosis of infection is limited. Aim: To determine the accuracy of a band count greater than 10% and increased or decreased white blood cell (WBC) count in diagnosing infection in a heterogeneous group of intensive care unit (ICU) patients. Methods: We prospectively recorded the WBC and band count on consecutive patients admitted to our ICU. Each patient was evaluated for the presence of infection according to defined criteria. The diagnostic accuracy of band count and total WBC count were determined by standard statistical methods. Results: Overall, 145 patients were enrolled, of whom 42 (29%) had a defined infection on admission to the ICU. On multiple logistic regression, the odds ratio for infection was 8.67 (95% CI 3.36-22.39; P < .001) for patients with band count greater than 10% and 1.6 (95% CI 0.78-3.29; P = .2) for a WBC count greater than 12 × 109/L. A band count greater than 10% had sensitivity of 43% (95% CI 28%-59%), specificity of 92% (95% CI 85%-97%), positive likelihood ratio of 5.52 (95% CI 2.6-11.7), and negative likelihood ratio of 0.62 (95% CI 0.47-0.81) for the diagnosis of infection. Conclusion: Band count may provide useful information in patients whose diagnosis of infection is uncertain. An elevated band count leads to a moderate increase in the likelihood of infection. A negative test, however, leads to only a small change in the posttest probability of infection.

What intensivists need to know about hemophagocytic syndrome: an underrecognized cause of death in adult intensive care units.

Hemophagocytic syndrome, also known as hemophagocytic lymphohistiocytosis (HLH), is a rare and frequently fatal disorder caused by an uncontrollable and ineffective systemic immune response. Patients initially present with fever, cytopenia, and hepatosplenomegaly, and subsequently develop multiorgan failure (MOF). Hemophagocytosis can be found on biopsy specimen but is not required. Acquired forms of HLH can occur in apparently healthy adults, while children present more often with an inherited form of the disease. Since HLH often presents with sepsis-like symptoms and organ dysfunction, patients are usually treated for presumed sepsis, which inevitably leads to delayed diagnosis and treatment. Intensivists need to have a low threshold for suspecting this disorder when previously healthy individuals present with a fulminant sepsis-like syndrome, which are unresponsive to conventional treatment. We present 3 patients with HLH who were admitted to our adult medical intensive care unit (MICU) over a 2-year period with fatal outcomes and emphasize the diagnostic importance of markedly elevated serum ferritin levels and the need for tissue biopsy in making an accurate diagnosis in a timely manner.

Influence of malignancy on the decision to withhold or withdraw life-sustaining therapy in critically ill patients.

Purpose: To evaluate the influence of malignancy on the decision to limit life-sustaining therapy in the intensive care unit (ICU). Methods: At the day of patients’ admission to the ICU, we prospectively collected information on demographics, acute physiology and chronic health evaluation (APACHE) II score, and features related to malignancy. We retrospectively collected information on in-hospital survival and decision to withhold or withdraw life-sustaining treatment. Results: This study included 122 adult critically ill patients. After adjusting for age and APACHE II score, patients with malignancy had 3.02 (95% CI 1.19 to 7.62) higher odds of having life-sustaining therapy withdrawn or withheld as compared to patients without active malignancy. Conclusion: Our study showed that critically ill patients with malignancy are more likely to have their life-sustaining therapy withheld or withdrawn than those without malignancy after adjusting for severity of disease. This finding may be related to a perception that critically ill patients with malignancy have worse prognosis as compared with those without malignancy.