Outcomes of major head and neck reconstruction during the COVID-19 pandemic: The St. Andrew's centre experience.

BACKGROUND: The coronavirus disease-2019 (COVID-19) pandemic has generated enormous pressure on healthcare establishments, prompting the restructuring of services to rationalise resources. Complex head and neck reconstructive surgery in this setting may carry substantial risk to patients and staff. This paper outlines the management strategy and outcomes of major head and neck oncological cases at a single regional tertiary referral centre. METHODS: A database review was undertaken of consecutive patients undergoing major head and neck surgery and reconstruction during the COVID-19 pandemic at St Andrew's Centre for Plastic Surgery & Burns, Chelmsford UK. Patient demographics, tumour and reconstruction characteristics as well as peri­operative information were determined. Patients were prospectively contacted with regard to COVID-related symptoms and investigations. RESULTS: Twenty-two patients (15 males and 7 females) with a mean age of 67 years (range: 36-92 years) were included between March 1 and June 13, 2020. Patients underwent pre-operative throat swabs at 72 h and 24 h as well as chest CT scanning as part of a robust protocol. Twelve free flaps, four loco-regional flaps, four parotidectomies and 23 cervical lymphadenectomies were performed. Two patients required a return to theatre. No post-operative deaths occurred and flap survival rate was 100%. A single patient tested positive for COVID-19 pre-operatively and no post-operative COVID-19 infections occurred. CONCLUSION: Although head and neck surgery represents a high-risk procedure to patients and healthcare professionals, our institutional experience suggests that in the presence of a robust peri­operative protocol and judicious patient selection, major head and neck surgery, including free tissue transfer reconstruction, may be performed safely.

A randomized pilot study to investigate the effect of opioids on immunomarkers using gene expression profiling during surgery.

Endogenous opioid peptides and exogenous opioids modulate immune function, and animal and human studies have shown that some have a depressant immunomodulatory effect. This is potentially of high clinical significance, eg, in cancer patients and surgery. The primary objective of this pilot study was to evaluate the effect of morphine and oxycodone on immune pathways associated with immunosuppression in gynecological laparotomy patients. Gene expression was analyzed in CD4, CD8, and natural killer (NK) cells using the 3' Affymetrix microarray. Patients were randomized to receive morphine, oxycodone, or nonopioid "control" analgesia during and after surgery. Genes demonstrating differential expression were those with a ≥±2-fold difference and P-value ≤0.05 after analysis of variance. Cytometric bead array and NK cell degranulation assay were used to investigate changes in serum cytokine concentration and in NK cell cytotoxicity, respectively. Forty patients had satisfactory RNA which was hybridized to gene chips. Genes were identified (Partek Genomics Suite 6.6) at baseline, 2, 6, and 24 hours and were either ≥2-fold upregulated or downregulated from baseline. At 2 hours, a large number of genes were downregulated with morphine but not with control analgesia or oxycodone. Statistically significant increases in IL-6 concentrations were induced by morphine only; NK cell activity was suppressed with morphine, but maintained with oxycodone and epidural analgesia. Gene expression profiles suggest that at 2 hours, post incision morphine appeared to be immunosuppressive as compared to oxycodone and nonopioid control analgesia.

Investigation of photoplethysmographic signals and blood oxygen saturation values obtained from human splanchnic organs using a fiber optic sensor.

OBJECTIVE: A reliable, continuous method of monitoring splanchnic organ oxygen saturation could allow for the early detection of malperfusion, and may prevent the onset of multiple organ failure. Current monitoring techniques have not been widely accepted in critical care monitoring. As a preliminary to developing a continuous indwelling device, this study evaluates a new handheld fiber optic photoplethysmographic (PPG) sensor for estimating the blood oxygen saturation (SpO(2)) of splanchnic organs during surgery. METHODS: A fiber optic splanchnic PPG sensor, instrumentation system and virtual instrument were developed to facilitate PPG and SpO(2) measurement from splanchnic organs. Following Local Research Ethics Committee approval, the sensor was evaluated on seventeen ASA 1 and 2 patients undergoing open laparotomy. PPG signals were obtained from the large bowel, small bowel, liver and stomach. Simultaneous PPG signals from the finger were also obtained using an identical fiber optic sensor. RESULTS: Good quality PPG signals with high signal-to-noise (SNR) ratios were obtained from all splanchnic sites under investigation. Analysis of the ac and dc amplitudes of the red and infrared PPG signals showed there to be a statistically significant difference between PPG signals obtained from splanchnic organs with those obtained from the finger (using fiber optic sensors). Estimated SpO(2) values from the splanchnic organs show good agreement with those obtained from the finger using both a fiber optic sensor and a commercial device. Furthermore, the results of a Bland and Altman analysis indicate that fiber optic splanchnic pulse oximetry, particularly of the bowel, may provide a suitable method for monitoring splanchnic organ perfusion. CONCLUSION: The evaluation of a new fiber optic sensor on anaesthetized patients undergoing laparotomy demonstrated that good quality PPG signals and SpO(2) estimates can be obtained from splanchnic organs. Such a sensor may provide a useful tool for the intraoperative assessment of splanchnic perfusion.

An in vivo investigation of photoplethysmographic signals and preliminary pulse oximetry estimation from the bowel using a new fiberoptic sensor.

BACKGROUND: The continuous monitoring of splanchnic organ oxygen saturation could make the early detection of inadequate tissue oxygenation feasible, reducing the risk of hypoperfusion, severe ischemia, multiple organ failure, and, ultimately, death. Current methods for assessing splanchnic perfusion have not been widely accepted for use in the clinical care environment. In an attempt to overcome the limitations of the current techniques, a new fiberoptic photoplethysmographic (PPG)/pulse oximetry sensor was developed as a means of assessing splanchnic organ perfusion during surgery in humans. METHODS: A new fiberoptic splanchnic pulse oximeter and an optically identical fiberoptic finger pulse oximeter have been developed. Simultaneous PPG signals and preliminary estimates of arterial oxygen saturation from the bowel (small and large) and finger were obtained in 17 patients (3 men and 14 women) undergoing open laparotomy. RESULTS: Good quality PPG signals were obtained from the small and large bowel and from the finger in all patients (lower 95% confidence limit for the proportion was 0.64). Comparisons of blood oxygen saturation values acquired when using the splanchnic and the finger fiberoptic sensors and a commercial finger pulse oximeter indicated that there was no statistically significant difference between them (all P>0.454). A Bland and Altman plot of the difference between blood oxygen saturation values from the bowel fiberoptic pulse oximeter and the fiberoptic finger pulse oximeter against their mean showed that the limits of agreement between the 2 pulse oximeters were -3.8% and 4.2% for small bowel measurements, and -3.4% and 4.3% for large bowel measurements. The 95% prediction interval for the difference between the 2 devices was between -4.2% and 4.7%. CONCLUSION: This study demonstrated that good quality PPG signals can be obtained from the bowel using a new fiberoptic sensor. Further evaluation is required to determine whether fiberoptic pulse oximetry of the bowel may provide a suitable method for monitoring splanchnic perfusion.

Measurement of splanchnic photoplethysmographic signals using a new reflectance fiber optic sensor.

Splanchnic organs are particularly vulnerable to hypoperfusion. Currently, there is no technique that allows for the continuous estimation of splanchnic blood oxygen saturation (SpO(2)). As a preliminary to developing a suitable splanchnic SpO(2) sensor, a new reflectance fiber optic photoplethysmographic (PPG) sensor and processing system are developed. An experimental procedure to examine the effect of fiber source detector separation distance on acquired PPG signals is carried out before finalizing the sensor design. PPG signals are acquired from four volunteers for separation distances of 1 to 8 mm. The separation range of 3 to 6 mm provides the best quality PPG signals with large amplitudes and the highest signal-to-noise ratios (SNRs). Preliminary calculation of SpO(2) shows that distances of 3 and 4 mm provide the most realistic values. Therefore, it is suggested that the separation distance in the design of a fiber optic reflectance pulse oximeter be in the range of 3 to 4 mm. Preliminary PPG signals from various splanchnic organs and the periphery are obtained from six anaesthetized patients. The normalized amplitudes of the splanchnic PPGs are, on average, approximately the same as those obtained simultaneously from the periphery. These observations suggest that fiber optic pulse oximetry may be a valid monitoring technique for splanchnic organs.