P. R. Westerbrook

Bio: P. R. Westerbrook is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 89 citations.

Pulmonary atelectasis: a pathogenic perioperative entity.

Abstract: Atelectasis occurs in the dependent parts of the lungs of most patients who are anesthetized. Development of atelectasis is associated with decreased lung compliance, impairment of oxygenation, increased pulmonary vascular resistance, and development of lung injury. The adverse effects of atelectasis persist into the postoperative period and can impact patient recovery. This review article focuses on the causes, nature, and diagnosis of atelectasis. The authors discuss the effects and implications of atelectasis in the perioperative period and illustrate how preventive measures may impact outcome. In addition, they examine the impact of atelectasis and its prevention in acute lung injury.

Effect of neuromuscular blocking agents on gas exchange in patients presenting with acute respiratory distress syndrome.

Abstract: ObjectiveTo evaluate the effects of a 48-hr neuromuscular blocking agents (NMBA) infusion on gas exchange over a 120-hr time period in patients with acute respiratory distress syndrome.DesignMultiple center, prospective, controlled, and randomized trial.SettingFour adult medical or mixed medical-sur

Perioperative functional residual capacity.

Abstract: The literature dealing with the magnitude, mechanism and effects of reduced FRC in the perioperative period is reviewed. During general anaesthesia FRC is reduced by approximately 20%. The reduction is greater in the obese and in patients with COPD. The most likely mechanism is the loss of inspiratory muscle tone of the muscles acting on the rib cage. Gas trapping is an additional mechanism. Lung compiance decreases and airways resistance increases, in large part, due to decreased FRC. The larynx is displaced anteriorly and elongated, making laryngoscopy and intubation more difficult. The change in FRC creates or increases intrapulmonary shunt and areas of low ventilation to perfusion. This is due to the occurrence of compression atelectasis, and to regional changes in mechanics and airway closure which tend to reduce ventilation to dependent lung zones which are still well perfused. Abdominal and thoracic operations tend to increase shunting further. Large tidal volume but not PEEP will improve oxygenation, although both increase FRC. Both FRC and vital capacity are reduced following abdominal and thoracic surgery in a predictable pattern. The mechanism is the combined effect ofincisional pain and reflex dysfunction of the diaphragm. Additional effects of thoracic surgery include pleural effusion, cooling of the phrenic nerve and mediastinal widening. Postoperative hypoxaemia is a function of reduced FRC and airway closure. There is no real difference among the various methods of active lung expansion in terms of the speed of restoration of lung function, or in preventing postoperative atelectasis/pneumonia. Epidural analgesia does not influence the rate of recovery of lung function, nor does it prevent atelectasis/pneumonia.

Respiratory system mechanics in sedated, paralyzed, morbidly obese patients.

Abstract: Pelosi, P., M. Croci, I. Ravagnan, M. Cerisara, P. Vicardi, A. Lissoni, and L. Gattinoni. Respiratory system mechanics in sedated, paralyzed, morbidly obese patients J. Appl. Physiol. 82(3): 811–81...

The effects of anesthesia and muscle paralysis on the respiratory system

Abstract: Background: Oxygenation is impaired in almost all subjects during anesthesia, and hypoxemia for shorter or longer periods is a common finding. Moreover, postoperative lung complications occur in 3–10% after elective abdominal surgery and more in emergency operations. Discussion: Rapid collapse of alveoli on induction of anesthesia and more widespread closure of airways seem to explain the oxygenation impairment and may also contribute to postoperative pulmonary infection. Causative mechanisms to atelectasis and airway closure seem to be loss of respiratory muscle tone and gas resorption. Conclusion: Avoiding high inspired oxygen fractions during both induction and maintenance of anesthesia prevents or reduces atelectasis, while intermittent “vital capacity” maneuvers recruit atelectatic lung regions.