Biomedical subjects

Michael Rhodes

Publications and source records attributed to Michael Rhodes.

5 recordsLinked to original sources

PubMed2003

Higher systemic arterial pressures are rarely associated with cerebral perfusion pressure deterioration in brain injury.

BACKGROUND: A computerized monitoring system was developed and utilized to evaluate the relationship between mean arterial pressure and intracranial pressure and its effect on cerebral perfusion pressure to determine how best to maximize cerebral perfusion pressure. METHODS: The monitoring system recorded mean arterial pressure and intracranial pressure, the values of which were used to calculate cerebral perfusion pressure. We developed the program for and utilized a "moving window" regression analysis to divide the total monitoring period into 2-hour overlapping epochs. The relationship between mean arterial pressure and intracranial pressure was then analyzed in each 2-hour epoch and classified into Types A, B, C, and D epochs, each with clinical significance. Type A epochs involved intracranial pressure increasing more than mean arterial pressure and resulted in deterioration of cerebral perfusion pressure. Type B epochs involved mean arterial pressure increasing more than intracranial pressure and resulted in an increase of perfusion pressure. Type C epochs involved mean arterial pressure increasing and intracranial pressure decreasing and also resulted in an increase in perfusion pressure. Type D epochs had no statistically significant relationship between mean arterial pressure and intracranial pressure. RESULTS: Forty-five patients with various pathologies were studied. The majority (n = 35) were patients with severe brain injury. Of 5,694 total hours monitored and 22,776 total epochs analyzed, 1.5% epochs were Type A, 5.9% were Type B, 2.1% were Type C, and 90.5% were Type D. CONCLUSION: In most patients, most of the time, increasing mean arterial pressure did not worsen cerebral perfusion pressure.

Aged↗

PubMed2003

Laparoscopic splenectomy: size matters.

BACKGROUND: Laparoscopic surgery is arguably the treatment of choice for patients undergoing elective splenectomy; however, for those patients with massive splenomegaly, laparoscopic surgery may prove difficult. PATIENTS AND METHODS: 6 years' experience of elective splenectomy was reviewed, in particular looking at the outcome of laparoscopic splenectomy in relation to the degree of splenomegaly. RESULTS: The conversion rate for laparoscopic splenectomy on patients with spleens weighing less than 1 kg was 0% whereas the conversion rate for those with spleens weighing more than 1 kg was 60%. In addition, a good correlation between both operative time and intra-operative blood loss in relation to splenic weight was observed. Open splenectomy on patients with spleens weighing more than 1 kg reduced the operative time and intra-operative blood loss without affecting hospital stay. CONCLUSIONS: Laparoscopic splenectomy is the method of choice for elective splenectomy in patients with splenic weight estimated to be < 1 kg; however, the operation takes longer, there is a high risk of conversion and there is an increase in blood loss/morbidity associated with massive splenomegaly (spleen > 1 kg) if splenectomy is attempted laparoscopically.

Blood Loss, Surgical↗

PubMed2002

The colon-selective spasmolytic otilonium bromide inhibits muscarinic M(3) receptor-coupled calcium signals in isolated human colonic crypts.

1. Otilonium bromide (OB) is a smooth muscle relaxant used in the treatment of irritable bowel syndrome. Otilonium bromide has been shown to interfere with the mobilization of calcium in intestinal smooth muscle, but the effects on other intestinal tissues have not been investigated. We identified the muscarinic receptor subtype coupled to calcium signals in colonic crypt derived from the human colonic epithelium and evaluated the inhibitory effects of OB. 2. Calcium signals were monitored by fluorescence imaging of isolated human colonic crypts and Chinese hamster ovary cells stably expressing the cloned human muscarinic M(3) receptor subtype (CHO-M(3)). Colonic crypt receptor expression was investigated by pharmacological and immunohistochemical techniques. 3. The secretagogue acetylcholine (ACh) stimulated calcium mobilization from intracellular calcium stores at the base of human colonic crypts with an EC(50) of 14 micro M. The muscarinic receptor antagonists 4-DAMP, AF-DX 384, pirenzepine and methroctamine inhibited the ACh-induced calcium signal with the following respective IC(50) (pK(b)) values: 0.78 nM (9.1), 69 nM (7.2), 128 nM (7.1), and 2510 nM (5.8). 4. Immunohistochemical analyses of muscarinic receptor expression demonstrated the presence of M(3) receptor subtype expression at the crypt-base. 5. Otilonium bromide inhibited the generation of ACh-induced calcium signals in a dose dependent manner (IC(50)=880 nM). 6. In CHO-M(3) cells, OB inhibited calcium signals induced by ACh, but not ATP. In addition, OB did not inhibit histamine-induced colonic crypt calcium signals. 7. The present studies have demonstrated that OB inhibited M(3) receptor-coupled calcium signals in human colonic crypts and CHO-M(3) cells, but not those induced by stimulation of other endogenous receptor types. We propose that the M(3) receptor-coupled calcium signalling pathway is directly targeted by OB at the level of the colonic epithelium, suggestive of an anti-secretory action in IBS patients suffering with diarrhoea.

Acetylcholine↗

PubMed2002

TRISS unexpected survivors: an outdated standard?

BACKGROUND: Performance improvement is an essential component of the trauma center. TRISS methodology has been applied as a national standard against which trauma centers can compare their outcomes. Earlier reviews of TRISS unexpected survivors sustained the classification of unexpected survivor in the vast majority of cases. Our hypothesis was that the level of care that is currently expected has made the TRISS unexpected survivors a statistical phenomenon only. METHODS: Two hundred seventy TRISS unexpected survivors at a Level I trauma center from 1991 to 1995 were reviewed. Each case was reviewed as a blinded abstract by six reviewers (three of whom are directors at other facilities) and classified as clinically unexpected survivor (confirmed TRISS classification) or clinically expected survivor (did not sustain TRISS classification as unexpected survivor). Data are expressed as mean +/- SD. Statistical significance was achieved at p < 0.05. RESULTS: Among the 270 patients categorized by TRISS as unexpected survivors, only 10.7% were corroborated as clinically unexpected survivors by this peer review process and 89.3% were reclassified as clinically expected survivors. Confirmed clinically unexpected survivors were more likely to go directly from the emergency department to the operating room (82 vs. 46%; p < 0.05). Age (32 +/- 12 years vs. 40 +/- 19 years; p < 0.05), Injury Severity Score (46 +/- 20 vs. 32 +/- 14; p < 0.05), Revised Trauma Score (2.46 +/- 1.89 vs. 3.11 +/- 1.21; p < 0.05), probability of survival (0.13 +/- 0.13 vs. 0.24 +/- 0.15; p < 0.05), systolic blood pressure in the emergency department (60 +/- 51 mm Hg vs. 109 +/- 33 mm Hg; p < 0.05), hospital length of stay (39.6 +/- 30.3 days vs. 24.0 +/- 23.0 days; p < 0.05), and intensive care unit length of stay (19.5 +/- 20.6 days vs. 9.6 +/- 10.1 days; p < 0.05) were significantly different comparing confirmed versus unsustained classification as unexpected survivors. CONCLUSION: Only 10.7% of survivors classified as unexpected by TRISS were corroborated as unexpected by a blinded, peer-review process. TRISS needs to be updated for meaningful interpretation; modifications need to be made and coefficients need to be revised.

Adult↗

PubMed2002

In-house trauma surgeons do not decrease mortality in a level I trauma center.

BACKGROUND: The value of an in-house trauma surgeon is debated. Previous studies focus on comparing in-house and on-call surgeons at different institutions or different periods in time. The purpose of this study was to simultaneously evaluate in-house and on-call trauma surgeons in a single Level I trauma center and to determine the impact of in-house trauma surgeons on the mortality of severely injured patients. METHODS: All records were reviewed for patients classified as major resuscitations from July 1997 through November 1999. Multiple logistic regression was performed to determine predictors of mortality on the basis of trauma surgeon status (in-house vs. on-call) and response time, while controlling for Injury Severity Score (ISS) and Revised Trauma Score. RESULTS: Of the 4,278 admissions, 537 were trauma codes. Mean ISS was 20.16 +/- 11.59. There was no difference between groups admitted by in-house surgeons versus on-call surgeons with respect to ISS or Revised Trauma Score. Mortality for the group was 24.8% (133 of 537); no statistical difference existed between observed and expected mortality by TRISS. The average response time was 3.96 minutes for the in-house group and 14.70 minutes for the on-call group (p < 0.001). Neither the call status nor the response time of the trauma surgeon significantly decreased emergency department or hospital mortality. There was a trend for improved outcome in those patients cared for by an in-house surgeon who were upgraded to a code, transferred into the institution, admitted during the night, or neurologically impaired. This trend did not reach statistical significance. CONCLUSION: When the trauma surgeon was rapidly available (< 15 minutes), there was no difference in emergency department or hospital mortality between in-house and on-call trauma surgeons. Selected subgroups of severely injured patients may benefit from an in-house trauma surgeon. If trauma surgeons are not readily available in an institution, an in-house call policy may be necessary for the prompt resuscitation of critically ill patients.

Adult↗