Reappraisal of systemic venous chemoreceptors: might they explain the matching of breathing to metabolic rate in humans?

New Findings

• What is the topic of this review?

  One of the major unanswered questions in physiology is that of how breathing matches metabolic rate. Venous chemoreceptors seem to have been dismissed since the 1960s.

• What advances does it highlight?

  New evidence shows that their apparent dismissal needs reappraisal.

  • The paper on which this depends has more than one interpretation, and another paper obtained the opposite result.
  • Previous search ignored all locations between skeletal muscle and the right heart.
  • Oxygen sensors other than the arterial chemoreceptors do exist. Heymans and colleagues originally demonstrated some residual breathing response to hypoxia in sino-aortically denervated animals. Similar results occur in humans.

One of the major unanswered questions in physiology is that of how breathing matches metabolic rate. The existence in humans of venous chemoreceptors that might control breathing seems to have been dismissed since the 1960s. New evidence has emerged showing that this apparent dismissal needs reappraisal. Firstly, the paper in humans on which this depends has more than one interpretation. Moreover, a previous paper obtained the opposite result and is not cited. Secondly, previous search for venous chemoreceptors failed to examine all venous locations between skeletal muscle and the right heart and lungs. Thirdly, oxygen sensors other than the arterial chemoreceptors do exist. Heymans himself originally demonstrated some residual breathing response to hypoxia in sino-aortically denervated animals. Others confirm a residual breathing response to hypoxia in mammals, including humans. There is now considerable interest in the importance of afferent feedback in controlling the cardiovascular and respiratory systems. Moreover, it is now clear that arterial, aortic and central chemoreceptors have no role in explaining how breathing matches metabolic rate. These together provide a timely reminder that venous chemoreceptors remain ideal candidates still to be considered as metabolic rate sensors to explain matching in humans. Firstly, this is because venous and values do change appropriately in proportion to metabolic rate, so a metabolic rate signal sufficient to drive breathing might already exist. Secondly, chemoreceptor-like anatomical structures are present in the systemic venous system but remain unexplored. Finally, no extant experimental evidence precludes their existence.

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The comings and goings of the vagus and the need to know your neural fulcrum

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Single-incision laparoscopic cholecystectomy for gallbladder torsion: A case report and literature review

Abstract

We present a case of preoperatively diagnosed gallbladder torsion (GT) that was successfully treated by single-incision laparoscopic cholecystectomy. An 80-year-old woman presented with sudden pain and a palpable mass in the right upper quadrant. Contrast-enhanced CT revealed ischemic changes, a swollen gallbladder with a V-shaped distortion of the extrahepatic ducts, and the gallbladder in an abnormal anatomical position; clinical findings indicated GT. We performed single-incision laparoscopic cholecystectomy and intraoperatively found that the floating gallbladder was twisted counterclockwise by 180° around the cystic duct. After an uneventful postoperative course, the patient was discharged on postoperative day 7. Laparoscopic cholecystectomy for a GT was first performed in 1994, and since then, 28 cases, including ours, have been treated laparoscopically. Laparoscopic cholecystectomy for GT could be the standard treatment for this condition, and single-incision laparoscopic cholecystectomy may be a good surgical option for patients with GT because of its anatomical characteristics.

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Laparoscopic transabdominal preperitoneal repair for strangulated inguinal hernia

Abstract

Introduction

Laparoscopic transabdominal preperitoneal repair (TAPP) is widely accepted in elective inguinal hernioplasty. However, given the scarcity of data, the feasibility and safety of TAPP in strangulated hernia cases have not yet been determined.

Methods

We retrospectively evaluated the data from a consecutive series of 33 patients who had undergone surgery for acute strangulated inguinal hernia associated with suspected visceral ischemic damage by either TAPP (TAPP group, n = 11) or conventional open hernioplasty via the anterior approach (anterior group, n = 22).

Results

The TAPP group had a significant longer surgical duration than the anterior group (147 vs 84 min) and relatively less blood loss. Incision and enlargement of the hernial orifice, which enables easy reduction of the strangulated organ, was performed in the last 7 of 11 cases in the TAPP group. The morbidity was lower in the TAPP group, but the difference was not statistically significant (18% vs 23%). The TAPP group had a significantly shorter postoperative hospital stay than the anterior group (7 vs 10 days).

Conclusion

For surgeons with sufficient knowledge of the anatomy and expertise in reducing the strangulated organ, TAPP for strangulated inguinal hernia is at least comparable to open hernioplasty via the anterior approach in short-term outcomes.

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Correlation between the pain numeric rating scale and the 12-item WHO Disability Assessment Schedule 2.0 in patients with musculoskeletal pain.

Objective: The aim of this study was to assess the correlation between pain severity measured on a numeric rating scale and restrictions of functioning measured with the WHO Disability Assessment Schedule (WHODAS 2.0). Patients and methods: This was a cross-sectional study of 1207 patients with musculoskeletal pain conditions. Correlation was assessed using Spearman's and Pearson tests. Results: Although all the Spearman's rank correlations between WHODAS 2.0 items and pain severity were statistically significant, they were mostly weak, with only a few moderate associations for 'S2 household responsibilities', 'S8 washing', 'S9 dressing', and 'S12 day-to-day work'. The correlation between the WHODAS 2.0 total score and pain severity was also moderate: 0.41 [95% confidence interval (CI): 0.36-0.45] for average pain and 0.42 (95% CI: 0.37-0.46) for worst pain. The correlation between the WHODAS 2.0 total score and pain level was also assessed using Pearson's product-moment correlation, yielding figures that were similar to Spearman's correlation: 0.42 (P

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New evidence for association of recessive IARS gene mutations with hepatopathy, hypotonia, intellectual disability and growth retardation

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Coronary Capillary Blood Flow in a Rat Model of Congestive Heart Failure

The aim of this study is to explore the role of abnormal coronary microvasculature morphology and hemodynamics in the development of congestive heart failure (CHF). Methods: CHF was induced in rats by aortic banding, followed by ischemia/reperfusion and later aortic debanding. Polymerized casts of coronary vasculature were imaged under a Scanning Electron Microscope (SEM). Matrix Laboratory (MATLAB) software was used to calculate Capillary Structure Index (CSI), a measure of structural alignment also called Mean Vector Length (MVL), for 93 SEM images of coronary capillaries (CSI-> 1 perfect linearity, CSI-> 0 circular disarray). CSI was incorporated as a constant to represent tortuosity and non-laminar flow in Poiseuille's equation in order to estimate the differences in capillary blood flow rate, velocity, and resistance for CHF versus control. Results: The morphology of congestive heart failure capillaries is significantly disordered and tortuous compared to control (CSI 0.35 ± 0.02 for 61 images from 7 CHF rats, 0.58 ± 0.02 for 32 images from 7 control rats. p<0.01). Estimated capillary resistance in congestive heart failure is elevated by 173% relative to control, while blood flow rate and blood velocity are 56% and 43% slower than control. Capillary resistance increased 67% due to the significantly narrower capillary diameter in congestive heart failure, while it increased an additional 105% due to tortuosity. Conclusions: The significant structural abnormalities of CHF coronary capillaries may drastically stagnatehemodynamics in myocardium and increase resistance to blood flow. This could play a role in the development of CHF.

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