Peritonitis and respiratory failure after abdominal operations

Intraabdominal Surgery and Anesthesia Management

Inspired Oxygenation in Surgical Patients During General Anesthesia With Controlled Ventilation: A Concept of Atelectasis. By Bendixen HH, Hedley-Whyte J, and Laver MB. New Engl J Med 1963; 269:991-996. Reprinted with permission.

ABSTRACT

The purpose of this study was to determine if the pattern of ventilation, by itself, influences oxygenation during anesthesia and surgery and examine the hypothesis that progressive pulmonary atelectasis may occur during constant ventilation whenever periodic hyperventilation is lacking, but is reversible by passive hyperinflation of the lungs. Eighteen surgical patients, ranging in age from 24 to 87 yr, without known pulmonary disease, were studied during intraabdominal procedures and one radical mastectomy. Although ventilation remained constant, changes occurred in arterial oxygen tension and in total pulmonary compliance, with an average fall of 22% in oxygen tension and 15% in total pulmonary compliance. This fall in oxygen tension supports the hypothesis that progressive mechanical atelectasis may lead to increased venous admixture to arterial blood. The influence of the ventilator pattern on atelectasis and shunting is further illustrated by the reversibility of the fall in oxygen tension that follows hyperinflation. A relation between the degree of ventilation and the magnitude of fall in arterial oxygen tension was found, where large tidal volumes appear to protect against falls in oxygen tension, while shallow tidal volumes lead to atelectasis and increased shunting with impaired oxygenation.

Peritonitis causes diaphragm weakness in rats

Respiratory failure is a common and often lethal complication of severe peritonitis. Because this inflammatory process develops in the abdomen, adjacent to the diaphragm, we hypothesized that peritonitis might directly compromise diaphragm function. We tested this hypothesis using male Sprague-Dawley rats. We injected oyster glycogen into the rats' peritoneum, and 16 h later the peritoneum was lavaged for leukocyte analysis and muscle samples were excised. Contractile properties of diaphragm fiber bundles were measured in vitro. We found that neutrophils and macrophages were concentrated in peritoneal lavage fluid of experimental animals (p < 0.01) and were adherent to the abdominal surface of the diaphragm. Immunohistochemistry showed increases in inducible nitric oxide synthase in microvessels of the diaphragm and limb skeletal muscles but not in heart or spleen. Peritonitis decreased maximal force production by the diaphragm (23.6+/-0.6 versus 21.2+/-0.6 N/cm2; p < 0.05) and decreased the absolute forces developed at physiologic stimulus frequencies (> 30 Hz; p < 0.01), depressing the overall force-frequency relationship (p < 0.001). Peritonitis had little effect on acute muscular fatigue. These data demonstrate that peritonitis weakens the diaphragm in rats and suggest that humans with peritonitis may be predisposed to respiratory muscle dysfunction.

Extended indications for polypropylene mesh closure of the abdominal wall

Over a two-year period (1982-1984) polypropylene (Marlex) mesh was used without closing the abdominal wound in 21 patients judged clinically likely to require further abdominal exploration. A total of 43 meshes were implanted. All 21 patients had more than one major laparotomy, median 3 laparotomies (range 2-7) for drainage of pus (76 per cent) and/or intestinal leakage (67 per cent). Definitive abdominal wound closure after removal of polypropylene mesh was either by delayed primary suturing (33 per cent) or consisted of split skin grafting on the granulating wound (24 per cent). Three wounds were left to granulate without skin grafting (14 per cent). Mortality in this group of patients was 29 per cent and no complications resulted directly from implantation of polypropylene mesh. Polypropylene mesh closure of the abdominal wall not only provides simple and rapid access to the abdomen but also allows free drainage and daily inspection for the development of fistulae or the seepage of pus which are indications for further exploration. In that the clinical outcome is relatively favourable in this group of critically ill surgical patients who required multiple laparotomies within a short interval, it is suggested that mesh closure of the abdominal wound is indicated whenever abdominal re-entry is judged probable or rational.

Acute respiratory failure in patients with generalized peritonitis

The evolution of acute respiratory failure was studied in 27 patients with generalized peritonitis. The natural history of pulmonary failure indicates an incidence of 74% of atelectasis progressing to pneumonitis in the majority of patients. In 21 patients, similar aerobic microorganisms were recovered from the sputum and abdominal focus of infection. The emergence of gram negative pneumonia by the third day of onset of peritonitis appeared to add significantly to respiratory failure. In the management of respiratory failure, early use of positive and expiratory pressure with mechanical ventilation was associated with improvement or reversal of hypoxia. A high fatality (89%) was attributed to uncontrolled sepsis rather than to respiratory failure.

Colloid osmotic pressure

Technical advances have made the bedside measurement of colloid osmotic pressure (COP) a rapid and reproducible test. The principles of measurement are described and the place of COP determinations in the recognition, treatment and prophylaxis of oedematous states is discussed.

Relationship between colloid osmotic pressure and pulmonary artery wedge pressure in patients with acute cardiorespiratory failure

Close relationships between progressive respiratory failure, roentgenographic signs of pulmonary opacification and decreases in the difference between colloid osmotic pressure of plasma and the pulmonary artery wedge pressure (colloid-hydrosatic pressure gradient) were demonstrated in 49 critically ill patients with multisystem failure, in patients in shock. The potential importance of this relationship is underscored by the observation that fatal progression of pulmonary edema was related to a critical reduction in the colloid-hydrostatic pressure gradient to levels of less than 0 mm Hg. More often, reduction in colloid osmotic pressure rather than increases in left ventricular filling pressure (pulmonary artery wedge pressure) accounted for the decline in colloid-hydrostatic pressure gradient. Routine measurement of colloid osmotic pressure, preferably in conjunction with pulmonary artery wedge pressure, is likely to improve understanding of the mechanisms of acute pulmonary edema.

Albumin uptake by skin, skeletal muscle and lung in living and dying patients

Quantitative changes in albumin and water content which occur in skin and muscle tissue obtained by biopsy from clean surgical incisions at the time of skin incision and at the time of wound closure were assessed in seven patients who had major abdominal and vascular operations. Biopsies from skin, muscle and pulmonary tissue were obtained in a second group of nine patients who had thoracotomy for suspected bronchogenic carcinoma. The intravascular albumin mass decreased linearly with the duration of the operation (r = 0.69, p <0.01) and was correlated significantly with a linear increase of extravascular albumin content in muscle (r = 0.63, p < 0.01). A significant increase of extravascular albumin occurred from the time of incision to the time of wound closure in the skin and muscle samples from both groups (p < 0.05-p < 0.001). Extravascular albumin and water content were assessed in a third group of three postoperative patients who died with acute respiratory failure. Although the concentration of extravascular albumin in pulmonary tissue taken from this group was not different from the thoracotomy group, calculations based on the mean combined post mortem lung weights showed two to three times more extravascular albumin content. The histopathological findings are consistent with these changes. Thoracotomy was not associated with an abnormal increase in pulmonary extravascular albumin and water content, possibly because albumin does not gain access to the pulmonary extravascular space in increased amounts during operation in this clinical setting.

Positive end-expiratory pressure in weaning patients from controlled ventilation. A prospective randomised trial

Twenty-five patients in acute respiratory failure were randomised to receive either 5 cm of positive end-expiratory pressure (P.E.E.P.) or no-P.E.E.P. while weaning from controlled ventilation. The use of P.E.E.P. resulted in a significant reduction in the increase in alveolar-arterial oxygen tension gradient (AaDO21) which occurred in the group of patients who were converted from controlled ventilation to spontaneous ventilation without P.E.E.P. Patients who weaned without P.E.E.P. had a mean increase in AaDO21 of 102+/-35 mm Hg S.E. while those who weaned with P.E.E.P. had a mean increase of only 10+/-22 mm Hg (P less than 0-03). The use of P.E.E.P. was also associated with a significant improvement in the vital capacity and the maximum inspiratory force. Patients who weaned with P.E.E.P. had an increase in vital capacity of 258+/-108 ml (P less than 0-05) and an increase in inspiratory force of -15+/-5 cm H2O (P less than 0-01), while patients who weaned without P.E.E.P. did not have significant changes in these measurements. The use of P.E.E.P. during weaning may be helpful in patients who fail to wean because of the development of hypoxaemia due to rapid alveolar collapse, since P.E.E.P. appears to minimise the increase in intrapulmonary right-to-left shunt which normally occurs during weaning from controlled ventilation.