14 Jan 12

Morbid obesity and postoperative pulmonary atelectasis: an underestimated problem

Posted in Anesthesia, Obesity at 1:01 by Laci

By A S Eichenberger, S Proietti, S Wicky, P Frascarolo, M Suter, D R Spahn, L Magnusson

Anesth Analg 2002;95:1788-1792

Perturbation of respiratory mechanics produced by general anesthesia and surgery is more pronounced in morbidly obese (MO) patients. Because general anesthesia induces pulmonary atelectasis in nonobese patients, we hypothesized that atelectasis formation would be particularly significant in MO patients. We investigated the importance and resorption of atelectasis after general anesthesia in MO and nonobese patients. Twenty MO patients were anesthetized for laparoscopic gastroplasty and 10 nonobese patients for laparoscopic cholecystectomy. We assessed pulmonary atelectasis by computed tomography at three different periods: before the induction of general anesthesia, immediately after tracheal extubation, and 24 h later. Already before the induction of anesthesia, MO patients had more atelectasis, expressed in the percentage of the total lung area, than nonobese patients (2.1% versus 1.0%, respectively; P < 0.01). After tracheal extubation, atelectasis had increased in both groups but remained significantly more so in the MO group (7.6% for MO patients versus 2.8% for the nonobese; P < 0.05). Twenty-four hours later, the amount of atelectasis remained unchanged in the MO patients, but we observed a complete resorption in nonobese patients (9.7% versus 1.9%, respectively; P < 0.01). General anesthesia in MO patients generated much more atelectasis than in nonobese patients. Moreover, atelectasis remained unchanged for at least 24 h in MO patients, whereas atelectasis disappeared in the nonobese.

Implications
We compared the resolution over time of pulmonary atelectasis after a laparoscopic procedure by performing computed tomography scans in two different groups of patients: 1 group had 10 nonobese patients, and in the other group there were 20 morbidly obese patients.

07 Mar 09

Anaesthesia and morbid obesity

Posted in Anesthesia, Obesity at 16:36 by Laci

By Sharmeen Lotia, M C Bellamy

Cont Edu Anaesth Crit Care & Pain.  2008;8:151-156

The prevalence of morbid obesity is increasing in the UK. Recent UK government statistics suggest that 20% of adults are obese and 1% morbidly obese. Anaesthesia and surgery may entail considerable risk for obese patients. Obesity is a multi-system disorder, particularly involving the respiratory and cardiovascular systems; therefore, a multidisciplinary approach is required. This article presents a broad overview of the pathophysiological and practical considerations for anaesthetizing such patients for major (non-bariatric) surgery.

A body mass index (BMI) of >35 kg m–2 with associated comorbidity, or >40 kg m–2 without significant comorbidity, is considered to be morbidly obese; >55 kg m–2 is considered super-morbidly obese (Table 1). However, morbidity and mortality increase sharply when BMI is >30 kg m–2, particularly in smokers, and risk is proportional to duration of obesity.1 For a given BMI, men are at higher risk of cardiovascular complications than women. Obesity is described classically as conforming to an android or gynaecoid fat distribution (‘apples and pears’). Both the actual BMI of a particular patient and the distribution of fat are important considerations. The gynaecoid fat distribution characteristically involves more fat distributed in peripheral, sites (arms, legs, and buttocks). An android fat distribution involves more central fat (intraperitoneal fat, including involvement of the liver and omentum). Specific definitions have been proposed based on the waist-to-hip ratio. A value >0.8 in women or 1.0 in men is typical of the android distribution. Although the android distribution predominates in males and is associated with a higher risk of morbidity, either distribution can occur in each gender. Weight loss reduces risk for both groups.

27 Mar 07

Outcomes of morbidly obese patients requiring mechanical ventilation for acute respiratory failure

Posted in Mechanical ventilation, Obesity at 18:50 by Laci

By A G Duarte, E BS Justino, T MS Bigler, J Grady

Critical Care Medicine. 2007;35:732-737

Objective
To examine the outcomes of morbidly obese patients with acute respiratory failure treated with mechanical ventilation.

Design
Retrospective study.

Setting
A 14-bed medical intensive care unit in an 800-bed university-based hospital.

Patients
A total of 50 morbidly obese subjects with acute respiratory failure requiring ventilatory assistance.

Measurements
Arterial blood gas measurements, intubation rate, days of mechanical ventilation, intensive care unit length of stay, hospital length of stay, and mortality.

Results
From January 1997 to December 2004, 50 morbidly obese patients with acute respiratory failure were treated with mechanical ventilation. Invasive mechanical ventilation was implemented in 17 patients with a mean body mass index of 53.2 +/- 12.2 kg/m2. A total of 33 patients were treated with noninvasive ventilation (NIV), of which 21 avoided intubation (NIV success) and 12 required intubation (NIV failure). Mean body mass index for the NIV success group was significantly less than for the NIV failure group (46.9 +/- 8.9 and 62.5 +/- 16.1 kg/m2, respectively, p = .001). Acute Physiology and Chronic Health Evaluation II scores were similar for patients treated with invasive and noninvasive ventilation. Significant improvements in pH and Paco2 were noted for the invasive mechanical ventilation and NIV success groups. No improvements in gas exchange were noted in the NIV failure group. Of patients treated with NIV, 36% required intubation. Hospital mortality for the invasive ventilation and NIV failure groups was increased.

Conclusion
The type of ventilatory assistance may influence clinical outcomes in morbidly obese patients with acute respiratory failure.

11 Dec 06

The effect of obesity on 12-month survival following admission to intensive care

Posted in Admission to ICU, Critical Care, Obesity at 15:23 by Laci

By S Peake, J L Moran, D R Ghelani, A J Lloyd, M J Walker

Critical Care Medicine 2006;34:2929-2939

Evaluate the effect of intensive care (ICU) admission body mass index (BMI) on 30-day and 12-month survival in critically ill patients and determine the impact of obesity on outcome.

Design
Prospective, observational cohort study.

Setting
Fourteen-bed medical and surgical ICU of a university-affiliated hospital.

Patients
Four hundred and ninety-three adult patients.

Interventions
None.

Measurements and Main Results
BMI (kg/m2) was calculated from height (m) and measured weight (kg) within 4 hrs of ICU admission, using the PROMED weighing device, or premorbid weight (documented in the previous month) (BMImeasured). Follow-up was for =12 months post-ICU admission. Time to mortality outcome, censored at 30 and 365 days (12-months), was analyzed using a log-normal accelerated failure time regression model. Predictor variables were parameterized as time ratios (TR), where TR <1 is associated with decreased survival time and TR >1 is associated with prolonged survival time. Mean (sd) age and Acute Physiology and Chronic Health Evaluation II score were 62.3 (17.5) years and 20.7(8.4), respectively; 56.0% (285 of 493) of patients were male and 60.6% (299 of 493) medical. ICU admission weight and BMImeasured (available in 433 patients) were 79.1 (22.1) kg and 27.8 (7.0) kg/m2, respectively. In 16.9% (73 of 433) of patients, weight was =100 kg, and in 29.8% (129 of 433), BMImeasured was =30 kg/m2. Raw intensive care, 30-day, and 12-month mortality rates were 15.2% (66 of 433), 22.3% (95 of 433), and 37.3% (159 of 433), respectively. BMImeasured was a significant determinant of mortality at 30 days (TR 1.853, 95% confidence interval 1.053-3.260, p = .032) and 12 months (TR 1.034, 95% confidence interval 1.005-1.063, p = .019). The effect of BMI on 12-month mortality was linear, such that increasing BMI was associated with decreasing mortality.

Conclusions
ICU admission BMI was a determinant of short- to medium-term survival. Obesity was not associated with adverse outcomes and may be protective.

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